US20040037076A1 - Light emitting diode lamp and light emitting diode display unit - Google Patents

Abstract

An LED lamp has a convex lens3which has an upper portion5and a lower portion6. An upper curved surface5A of the upper portion is different in shape from a lower curved surface6A of the lower portion6so as to refract rays of light from an LED chip2more strongly than the lower curved surface6A does. This avoids reflection of incident outside light toward a front and hence prevents misrecognition. An interface plane S1 between the upper and lower portions5and6of the convex lens3is located on an upper end face2A to thereby prevent collection of outgoing light upon the interface plane S1 and generation of an irregular emission peak at the front.

Description

BACKGROUND OF THE INVENTION
• The present invention relates to a light emitting diode. (“LED”) lamp and an LED display unit, which are preferably used, for example, in outdoor LED display boards for displaying road information such as traffic information as well as for outdoor display for advertisement, signalers and the like.[0001]
• Conventionally, there has been an LED lamp shown in FIG. 10. This LED lamp is structured such that an[0002]LED chip102 mounted on alead frame101 is resin-molded and embedded in aresin lens103. Theresin lens103 has acurved surface103A that is curved in a convex shape in the light emitting direction of the LED chip102 (see Japanese Patent Laid-Open Publication HEI 11-154766 and Japanese Patent Laid-Open Publication HEI 10-22529, for example).
• The conventional LED lamp shown in FIG. 10 produces a phenomenon, when used in an outdoor LED display board for example, that in the evening and early morning when an irradiation angle of sunlight is low, sunlight directly comes incident upon the LED lamp and gives the unlit LED lamp the appearance as if it is lit. This phenomenon lessens a contrast ratio of a lit LED lamp to an unlit LED lamp, which may make the LED display board less recognizable. This phenomenon, which is similar to misread of signalers due to afternoon sunlight, causes remarkable deterioration of display quality of the LED display board that constitutes electronic billboards, signboards, and the like.[0003]
• With reference to FIG. 12, more detailed description will be given of the above-stated phenomenon of the conventional LED lamp. When the rays of[0004]sunlight111a,111bwith low irradiation angles in the evening and early morning, as shown in FIG. 12, become incident upon aresin lens103, they are refracted by acurved surface103A of theresin lens103, so that their traveling directions approximate to normal lines L101, L102 at incident points P101, P102. By this refraction, the rays ofsunlight111a,111bare incident upon and reflected by a portion of alead frame101 on or around which anLED chip102 is mounted, as a consequence of which, at an incident angle close to the emission angle of the emitted rays of light from theLED chip102, the reflected rays oflight111a,111bcomes incident upon and refracted by thecurved surface103A of theresin lens103, and therefore the refracted rays of light exits in approximately parallel to an exit optical axis J101. This is the phenomenon that an unlit LED lamp looks like a lit LED lamp.
• Next, another conventional example is shown in FIG. 11. This conventional example is similar to the above-described conventional example in that an[0005]LED chip102 is mounted on alead frame101, but different in that there is provided alens105 having upper and lowercurved surfaces105A and105B whose shapes are different from each other (see Japanese Patent Laid-Open Publication HEI 11-154766 for example). If the upper and lower curved surfaces are considerably different in curvature as with this conventional example, rays of light are concentrated upon an interface of these twocurved lens surfaces105A,105B, which generates an irregular emission peak on the front side. Consequently, the apparent luminescence intensity becomes remarkably different between a view from the front side and a view with a viewpoint slightly displaced downward from the front side, thereby causing degradation of display quality.
• Also, when the positional relationship between the light emitting diode chip and the interface of the lenses is changed due to production variations, the emission angle at the above-mentioned emission peak varies, so that particularly an LED display board composed of a lot of light emitting diode lamps disposed in a matrix form produces uneven display when viewed from the front side.[0006]
• In the former conventional example as described above, the installation site of the LED display board should be taken into consideration. In the places exposed to afternoon sunlight, the board cannot be installed at all or should be installed with the display surface of the LED display board inclined downward. Therefore, particularly in the case of traffic information boards, there have been cases in which the conventional board could not be applied as a display board whose original function is to secure traffic safety.[0007]
• Also, as is the case with the latter conventional example, simple combination of upper and lower lenses with different curvatures produces uneven display as viewed from the front-side direction.[0008]
SUMMARY OF THE INVENTION
• Accordingly, it is an object of the present invention to provide an LED lamp and an LED display unit capable of preventing misrecognition due to incident rays of light from the outside, such as reflected rays of sunlight, without causing uneven display.[0009]
• In order to achieve the above object, an LED lamp according to one aspect of the present invention includes at least one LED chip, and a convex lens through which rays of light emitted from the at least one LED chip pass. The convex lens has two different curved surfaces on both sides of a plane orthogonal to a light emitting surface of the LED chip or to an extension of the light emitting surface and extending off a center of the light emitting surface, and one of the curved surfaces of the convex lens is a curved surface that refracts outgoing rays of light from the LED chip more greatly than the other of the curved surfaces of the convex lens does.[0010]
• This LED lamp of the present invention is structured such that the curved surface on one side of the convex lens is different in shape from the curved surface on the other side of the convex lens and refracts rays of light emitted from the LED chip larger than the other-side curved surface does. An outside ray of light that comes incident at a shallow angle (as typified by afternoon light and the like) upon the other-side curved surface of the convex lens is refracted and reaches the vicinity of the location where the LED chip is mounted, and on this location the ray of light is reflected and comes incident from the inside upon the one-side curved surface. The outside ray of light incident upon the one-side curved surface is steeply refracted by the one-side curved surface and emitted toward the other side. If that outside ray of light comes incident from the inside upon the one-side curved surface at an incident angle beyond a critical angle, the outside ray of light is totally reflected by the one-side curved surface and does not exit from the convex lens. It should be noted that the one-side curved surface refracts the outgoing rays of light, which are emitted from the LED chip and have an identical outgoing angle, larger than the other-side curved surface does. Herein, one side may be set as the upper side and the other side may be set as the lower side, for example.[0011]
• Accordingly in the present invention, if outside rays of light come incident, reflection of the outside rays of light to the front side is avoidable, and therefore misrecognition of an unlit diode lamp as being lit is prevented.[0012]
• Further in the present invention, since the curved surfaces are disposed on one side and the other side of a plane extending off the center of the light emitting surface, outgoing rays of light from the LED chip are prevented from concentrating upon a plane extending through the center of the light emitting surface, thereby enabling prevention of an irregular light emitting peak from being produced on the front side. This makes it possible to avoid a phenomenon of rapid decline of luminous intensity only with slight displacement of a viewpoint from the front side. According to the present invention, therefore, misrecognition due to incident rays of light from the outside, such as reflected rays of light, can be prevented without causing uneven display.[0013]
• In one embodiment, the plane extending off a center of the light emitting surface is orthogonal to the extension of the light emitting surface of the LED chip and does not intersect with the LED chip.[0014]
• In this embodiment, outgoing rays of light from the LED chip can be more securely prevented from concentrating upon the plane going through the center of the light emitting surface, which ensures prevention of uneven display, thereby enabling increase of display quality.[0015]
• In one embodiment, the LED lamp has more than one LED chips, which are arrayed in one direction.[0016]
• In the LED lamp of the present embodiment, a plurality of LED chips are arrayed in one direction, which makes it possible to increase luminance while uneven display and misrecognition being prevented. Also, by arranging the LED chips so as to emit rays of light having wavelengths different from each other, a multicolor LED lamp is implemented.[0017]
• In one embodiment, the at least one LED chip is molded by resin having a light absorption band in wavelengths other than a peak wavelength of rays of light emitted by the LED chip, and the resin constitutes the convex lens.[0018]
• In the LED lamp of the present embodiment, the resin constituting the convex lens has a light absorption band in the wavelengths other than the wavelength peak of rays of light emitted by the LED chip. This makes it possible to attenuate rays of light of unnecessary wavelengths and to increase display quality.[0019]
• In one embodiment, the at least one LED chip is mounted on a black surface-treated lead frame.[0020]
• This makes it possible to restrain the outside rays of light incident from the outside upon the convex lens from being reflected by the lead frame, and ensures prevention of misrecognition of an unlit diode lamp as being lit.[0021]
• In one embodiment, the LED lamp further includes a reflection cup surrounding at least a part of a periphery of the LED chip, and an inner peripheral surface of the reflection cup is black surface-treated.[0022]
• The black surface treated inner peripheral surface of the reflection cup restrains the outside rays of light entering the convex lens from being reflected to thereby restrain the outside rays of light from exiting from the convex lens to the outside. This ensures prevention of misrecognition of an unlit diode lamp as being lit.[0023]
• In one embodiment, black-colored resin is mounted on a lead frame on which the LED chip is mounted, the black-colored resin being positioned behind the LED chip.[0024]
• This black-colored resin forms a back surface of the LED chip, so that a contrast is improved.[0025]
• Also, in one embodiment, an LED display unit has the above-described LED lamp. The LED display unit is capable of preventing misrecognition due to incident rays of light from the outside, without causing uneven display.[0026]
• In one embodiment, at least one of the above two curved surfaces of the convex lens comprises a plurality of curved surfaces different in shape.[0027]
• Therefore, it becomes possible to regulate the direction of rays of light outgoing from the curved surfaces of the convex lens by making each curved surface refract emissions from the LED chip with different powers.[0028]
• In one embodiment, the plurality of curved surfaces include a curved surface on one side and a curved surface on the other side of a plane that is orthogonal to the extension of the light emitting surface of the LED chip and that does not intersect with the LED chip.[0029]
• The LED lamp of the present embodiment is capable of preventing outgoing rays of light from an LED chip from concentrating upon the plane going through the light emitting surface, by which generation of un irregular light emitting peak at the front is prevented. This enables prevention of uneven display to thereby increase the display quality.[0030]
• Other objects, features and advantages of the present invention will be apparent from the following description.[0031]
BRIEF DESCRIPTION OF THE DRAWINGS
• The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not intended to limit the present invention, and wherein:[0032]
• FIG. 1 is a side view of an LED lamp in a first embodiment of the present invention;[0033]
• FIG. 2 is an explanatory view showing outside rays of light being refracted and reflected in the first embodiment;[0034]
• FIG. 3 is a front view of an LED lamp in a second embodiment of the present invention;[0035]
• FIG. 4 is a front view of an LED lamp in a third embodiment of the present invention;[0036]
• FIG. 5 is a perspective view of an LED lamp in a fourth embodiment of the present invention;[0037]
• FIG. 6 is a perspective view of an LED lamp in a fifth embodiment of the present invention;[0038]
• FIG. 7 is a perspective view of an LED lamp in a sixth embodiment of the present invention;[0039]
• FIG. 8 is a perspective view of an LED lamp in a seventh embodiment of the present invention;[0040]
• FIG. 9 is a cross sectional view of the LED lamp in the seventh embodiment;[0041]
• FIG. 10 is a side view of a conventional LED lamp;[0042]
• FIG. 11 is a side view of another conventional LED lamp;[0043]
• FIG. 12 is an explanatory view showing outside rays of light being refracted and reflected by the conventional LED lamp of FIG. 10;[0044]
• FIG. 13 is a side view showing an LED lamp in an eighth embodiment of the present invention;[0045]
• FIG. 14 is a front view of an LED lamp in a ninth embodiment of the present invention;[0046]
• FIG. 15 is a perspective view of an LED lamp in a tenth embodiment of the present invention;[0047]
• FIG. 16 is a perspective view of an LED lamp in an eleventh embodiment of the present invention;[0048]
• FIG. 17 is a perspective view of an LED lamp in a twelfth embodiment of the present invention;[0049]
• FIG. 18 is a perspective view of an LED lamp in a thirteenth embodiment of the present invention;[0050]
• FIG. 19 is a longitudinal sectional view of the LED lamp in the thirteenth embodiment; and[0051]
• FIG. 20 is a view showing an embodiment of an LED display unit having the LED lamp of the present invention.[0052]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Hereinbelow, detailed description will be given of the embodiment of the present invention with reference to the drawings.[0053]
• (First Embodiment)[0054]
• FIG. 1 shows an LED lamp in a first embodiment of the present invention seen from the side. In the first embodiment, an[0055]LED chip2 is mounted on a cup-shaped mountingportion1A of alead frame1. TheLED chip2 and the mountingportion1A are embedded in aconvex lens3 made of resin. The resinconvex lens3 forms a convex lens protruding in the emission direction of rays of light from theLED chip2, and has anupper portion5 including an uppercurved surface5A exemplifying a curved surface on one side and alower portion6 including a lowercurved surface6A exemplifying a curved surface on the other side. In operation, the LED lamp uses a direction perpendicular to alight emitting surface2B of theLED chip2 as a frontward direction and the direction parallel to thelight emitting surface2B as an upward/downward direction. In use, theupper portion5 is located on the upper side while thelower portion6 is located on the lower side.
• An interface plane S1 between the[0056]upper portion5 andlower portion6 is a plane that is orthogonal to an extension of thelight emitting surface2B of theLED chip2 and that extends off the center of thelight emitting surface2B and is located higher by a distance D1 than an exit optical axis J1 of theLED chip2. The interface plane S1 is located above an extended surface of anupper end surface2A of theLED chip2. Also, in the resinconvex lens3, an angle between the uppercurved surface5A of theupper portion5 and the interface plane S1 is smaller than an angle between the lowercurved surface6A of thelower portion6 and the interface plane S1. More particularly, the uppercurved surface5A, which is different in shape from the lowercurved surface6A, is shaped to refract rays of light emitted by theLED chip2 more strongly than the lowercurved surface6A does. In other words, theconvex lens3 has vertically asymmetric lens curvatures.
• FIG. 2 shows that rays of sunlight (e.g., afternoon light)[0057]11a,11bof evening and early morning time having shallow irradiation angles relative to the resinconvex lens3 in this first embodiment enter the lowercurved surface6A of thelower portion6 of the resinconvex lens3 at respective incident points P1, P2. It is noted that theLED chip2 is omitted from FIG. 2. In this case, the ray ofsunlight11ais refracted by the lowercurved surface6A of thelower portion6 of the resinconvex lens3 at the incident point P1, and reaches acentral portion1A-1 of the mountingportion1A. Thecentral portion1A-1 of the mountingportion1A is a portion at which the exit optical axis J1, which is a center in the upward/downward direction of theLED chip2, meets the mountingportion1A. The ray ofsunlight11aincident upon thecentral portion1A-1 of the mountingportion1A is reflected by thecentral portion1A-1, and exits in approximately parallel to the exit optical axis J1 from anupper end portion6A-1 of the lowercurved surface6A in thelower portion6 of the resinconvex lens3. Theupper end portion6A-1 is closer to the interface plane S1 than the exit optical axis J1 is. In other words, theupper end portion6A-1 is positioned above the exit optical axis J1.
• The ray of[0058]sunlight11bincident upon the incident point P2 of the lowercurved surface6A, which is located below the incident point P1 for the ray ofsunlight11a, is refracted by the lowercurved surface6A and comes incident upon aportion1A-2 that is located lower than thecentral portion1A-1 of the mountingportion1A of thelead frame1. An incident angle of the ray ofsunlight11bupon theportion1A-2 is larger than an incident angle of the ray ofsunlight11aupon thecentral portion1A-1. This is because the incident angle of the ray ofsunlight11bupon the lowercurved surface6A is larger than the incident angle of the ray ofsunlight11aupon the lowercurved surface6A, as a consequence of which the ray ofsunlight11bis refracted on the lowercurved surface6A more greatly than the ray ofsunlight11ais.
• Accordingly, the ray of[0059]sunlight11bis reflected on theportion1A-2 of the mountingportion1A at an angle larger than that of the ray ofsunlight11a. Consequently, the ray ofsunlight11bcomes incident upon the uppercurved surface5A of theupper portion5. Since an incident angle θ1 of the ray ofsunlight11bupon the uppercurved surface5A exceeds a critical angle θcr, the ray ofsunlight11bis totally reflected by the uppercurved surface5A and cannot exit to the outside from the uppercurved surface5A. Given that a refraction index of outside air is m1 and a refraction index of the resin constituting the resinconvex lens3 is m2, the critical angle θcr is calculated by the formula (1) below. In the first embodiment, for example, the critical angle θcr is 41°.
• θcr=sin⁻¹(m1/m2)  (1)
• In the first embodiment, the upper[0060]curved surface5A of theupper portion5 is a curved surface that refracts rays of light emitted by theLED chip2 larger than the lowercurved surface6A of thelower portion6 does. Consequently, as is the case with the above-mentioned ray ofsunlight11b, some outside rays of light that come incident from the outside upon the lowercurved surface6A of the resinconvex lens3 and are reflected in the vicinity of theLED chip2 are totally reflected by the uppercurved surface5A as described above and therefore do not exit from the resinconvex lens3. Other outside rays of light are refracted by the uppercurved surface5A so as to be directed downward. Therefore, according to theLED chip2 having the resinconvex lens3, it becomes possible to prevent the misrecognition that an unlit LED lamp is lit, due to incident rays of light from the outside such as afternoon light.
• Also in the first embodiment, the interface plane S1 between the[0061]upper portion5 and thelower portion6 of the resinconvex lens3 is located above the exit optical axis J1 of theLED chip2, which makes it possible to prevent outgoing rays of light from theLED chip2 from concentrating upon the interface plane S1 to thereby prevent generation of an irregular light emitting peak on the front side. Therefore, it becomes possible to avoid a phenomenon of abrupt decline of luminous intensity only with slight displacement of a view point from the front.
• In the first embodiment, therefore, misrecognition due to incident rays of light from the outside such as reflected rays of light can be prevented without causing uneven display.[0062]
• (Second Embodiment)[0063]
• Next, FIG. 3 shows an LED lamp in a second embodiment of the present invention seen from the front side. In the second embodiment, two[0064]LED chips22,23 are mounted on a mountingportion21A of alead frame21. These twoLED chips22,23 are connected to respective electrode leads25,26 on both sides of thelead frame21 throughconnection wires27,28.
• The mounting[0065]portion21A, the twoLED chips22,23, and the electrode leads25,26 are embedded in aconvex lens24 made of resin. Theconvex lens24 is convex toward the light emitting direction of the twoLED chips22,23. Theconvex lens24 is composed of anupper portion31 and alower portion32 which abut on each other in an interface plane S2. The interface plane S2 is a plane that is orthogonal to an extension of light emittingsurfaces22B,23B of the LED chips22,23 and does not pass the LED chips22,23. In operation, the LED lamp uses the direction perpendicular to thelight emitting surfaces22B,23B of the LED chips22,23 as a frontward direction and the direction parallel to thelight emitting surface22B as a vertical, or upward/downward direction. In use, theupper portion31 is located on the upper side while thelower portion32 is located on the lower side. Theupper portion31 has an uppercurved surface31A as a surface on one side and thelower portion32 has a lowercurved surface32A as a surface on the other side. The interface plane S2 is parallel to an optical axis plane S3 containing exit optical axes that are vertical centers of therespective LED chips22,23, and the optical axis plane S3 is away from the interface plane S2 by a distance D2. As shown in FIG. 3, the interface plane S2 is positioned above the LED chips22,23 on the mountingportion21A. The LED chips22,23 are arrayed in a lateral direction parallel to the interface plane S2.
• The[0066]upper portion31 of theconvex lens24 includes a maximum thickness portion30 in which a vertical thickness of theupper portion31 is maximal, on an orthogonal plane S5. The orthogonal plane S5 extends through a central axis J2 between the LED chips22 and23 on the optical axis plane S3 and is also orthogonal to the optical axis plane S3. Thelower portion32 of theconvex lens24 also includes amaximum thickness portion33 in which a vertical thickness of thelower portion33 is maximal, on the orthogonal plane S5.
• The[0067]convex lens24 is structured such that the uppercurved surface31A of theupper portion31 is a curved surface that refracts outgoing rays of light from the LED chips22,23 larger than the lowercurved surface32A of thelower portion32 does, and makes the rays of the light exit from theconvex lens24. According to the second embodiment, therefore, during operation, as with the first embodiment, it becomes possible to prevent the misrecognition of an unlit LED chip as being lit, due to incident rays of light from the outside such as afternoon light. Further, the interface plane S2 between theupper portion31 and thelower portion32 of theconvex lens24 is positioned higher than the optical axis plane S3 by a distance D2 and positioned above the LED chips22,23. According to the second embodiment, therefore, it becomes possible to prevent outgoing rays of light from the LED chips22,23 from being concentrated upon the interface plane S2 so as to prevent generation of an irregular light emitting peak at the front. This makes it possible to avoid a phenomenon of rapid decline of luminous intensity only with slight displacement of a view point from the front, or head-on side. Therefore in the second embodiment, misrecognition due to incident rays of light from the outside can be prevented without causing uneven display.
• Further in the second embodiment, for example, the[0068]LED chip22 is set to be a red-color LED and theLED chip23 is set to be a green-color LED so as to implement a multicolor-lighting LED lamp. It should be understood that a lighting color combination of the LED chips22 and23 is not limited to the combination of red-color and green-color, and a combination of red-color and blue-color as well as a combination of yellow-color and green-color are also applicable. Giving the same color to the twoLED chips22,23 enables increase of luminance. Although there are provided two LED chips in the second embodiment, there may be provided more than two LED chips.
• (Third Embodiment)[0069]
• Next, FIG. 4 shows an LED lamp in a third embodiment of the present invention seen from the front side. In the third embodiment, an[0070]LED chip42 is mounted on a mountingsurface41A of alead frame41, and theLED chip42 is connected to anelectrode lead46 through aconnection wire48.
• The[0071]lead frame41, theLED chip42, and theelectrode lead46 are embedded in aconvex lens44 made of resin. Theconvex lens44 is convex toward the light emitting direction of the LED chip42 (i.e., a direction perpendicular to the drawing sheet). Theconvex lens44 is mounted on abody55 made of resin. On both sides of thebody55, there aredisposed connection terminals56,57 for connection to a printed wiring board (unshown). Theconnection terminal56 is electrically connected to thelead frame41 while theconnection terminal57 is electrically connected to theelectrode lead46.
• The LED lamp, during operation, uses the direction perpendicular to a[0072]light emitting surface42B of theLED chip42 as a frontward direction and the direction parallel to thelight emitting surface42B as a vertical, or upward/downward direction. Theconvex lens41 is composed of anupper portion51 and alower portion52 in the above-stated upward/downward direction, and theupper portion51 and thelower portion52 abut on each other in an interface plane S11. The interface plane S11 is a plane that is orthogonal to an extension of thelight emitting surface42B of theLED chip42 and does not intersect with theLED chip42.
• The[0073]upper portion51 has an uppercurved surface51A as the one-side surface and thelower portion52 has a lowercurved surface52A as the other-side surface. An optical axis plane S12 going through a vertical center of the light emitting surface of theLED chip42 is parallel to the interface plane S11, and the optical axis plane S12 is away from the interface plane S11 by a distance D3.
• The upper[0074]curved surface51A of theupper portion51 is a curved surface that refracts outgoing rays of light from theLED chip42 more greatly than the lowercurved surface52A of thelower portion52 does.
• Accordingly, given that an angle calculated by extracting an incident angle θi1 at which a ray of emitted light from the[0075]LED chip42 impinges upon the uppercurved surface51A from an outgoing angle θo1 at which an emitted ray of light exits from the uppercurved surface51A is expressed as θo1−θi1=Δθ1, and that an angle calculated by extracting an incident angle θi2 at which a ray of emitted light from theLED chip42 impinges upon the lowercurved surface52A from an outgoing angle θo2 at which an emitted ray of right exits from the lowercurved surface52A is expressed as θo2−θi2=Δθ2, then Δθ1 is larger than Δθ2.
• According to the third embodiment, therefore, as with the first embodiment, during operation, it becomes possible to prevent the misrecognition of an[0076]unlit LED chip42 as being lit due to incident rays of light from the outside such as afternoon light. Also, the interface plane S11 between theupper portion51 and thelower portion52 of theconvex lens44 is located higher than the optical axis plane S12 by the distance D3, and is located above theLED chip42. According to the third embodiment, therefore, it becomes possible to prevent outgoing rays of light from theLED chip42 from being concentrated upon the interface plane S11 so as to prevent generation of an irregular light emitting peak on the front side of the chip. This makes it possible to avoid a phenomenon of rapid decline of luminous intensity only with slight displacement of a view point from the front side of the chip. Therefore in the third embodiment, misrecognition due to incident rays of light from the outside such as sunlight may be prevented without causing uneven display.
• It is noted that in the third embodiment, the resin[0077]convex lens44 with theLED chip42 embedded therein is mounted on the upper surface of theresin body55 to form a surface-mounted LED lamp. However, the present invention is also applicable to LED lamps of a type that incorporates theconvex lens44 in theresin body55, and to a type that theresin lens44 pierces the upper surface of thebody55.
• (Fourth Embodiment)[0078]
• Next, FIG. 5 shows a fourth embodiment. In the fourth embodiment, the[0079]convex lens24 made of resin in the above-described second embodiment is replaced with a convex lens made of epoxy resin which is mixed with a pigment that transmits rays of light having specified wavelengths (e.g., a wavelength corresponding to a green-color and a wavelength corresponding to a red-color) and attenuates rays of light having wavelengths other than the specified wavelengths. In this case, if, for example, theLED chip22 is designed to emit red-color light, and theLED chip23 is designed to emit green-color light, it becomes possible to attenuate practically unnecessary emitted light, thereby enabling further improvement of display quality.
• Alternatively, the epoxy resin that forms the[0080]convex lens24 may be mixed with a pigment having a light absorption band in the wavelengths other than the wavelength corresponding to green-color and the wavelength corresponding to red-color. In this case, unnecessary rays of light other than green-color and red-color lights are absorbed and attenuated by the convex lens, which increases display quality. It is noted that the materials that constitute theconvex lens24 may be resin other than the epoxy resin. If the pigment cannot be mixed in the resin, the pigment may be applied to the surface of theconvex lens24. Further, it is also possible to cover the surface of theconvex lens24 with a cover with the pigment mixed therein.
• (Fifth Embodiment)[0081]
• Next, a fifth embodiment is shown in FIG. 6. The fifth embodiment is different from the above-described second embodiment only in that instead of the[0082]lead frame21, and the electrode leads25,26 of the second embodiment in FIG. 3, alead frame62 and electrode leads63,61 are provided.
• In the fifth embodiment, black surface treatment is applied to a mounting[0083]surface62A of thelead frame62 so as to make light reflectance of the mountingsurface62A 80% or less. The black surface treatment is also applied tosurfaces63A,61A of the electrode leads63,61 so as to make light reflectance of thesurfaces63A,61A 80% or less. LED chips22,23 are mounted on the mountingsurface62A, and theLED chip22 is connected to thesurface63A of theelectrode lead63 through aconnection wire27. TheLED chip23 is connected to thesurface61A of theelectrode lead61 through aconnection wire28.
• In the fifth embodiment, light reflectance of the mounting[0084]surface62A of thelead frame62 is set to 80% or less, and light reflectance of thesurfaces63A,61A of the electrode leads63,61 is set to 80% or less, which makes it possible to restrain outside rays of light having entered theconvex lens24 from reflecting on the mountingsurface62A and thesurfaces63A,61A. Accordingly, it becomes possible to restrain outside rays of light entering theconvex lens24 from exiting from theconvex lens24, and to ensure prevention of misrecognition of an unlit diode lamp as being lit. As described above, in the fifth embodiment, black surface treatment is applied to set light reflectance of the mountingsurface62A of thelead frame62 and thesurfaces63A,61A of the electrode leads63,61 to be 80% or less. This is because reflectance of over 80% provides an insufficient reflection inhibition effect.
• (Sixth Embodiment)[0085]
• Next, FIG. 7 shows an LED lamp in a sixth embodiment of the present invention. The sixth embodiment is different from the above-described fifth embodiment only in the point that in a position retreated by a specified distance from the[0086]surfaces62A,63A and61A of thelead frame62 and of the electrode leads63,61 in the fifth embodiment of FIG. 6 in a direction opposite from the light emitting direction, there is provided a black-color resin piece71 that extends from the inside of theconvex lens24 beyond itsbottom surface24C to the outside.
• A[0087]neck portion62A of thelead frame62, a bendingportion63A of theelectrode lead63, and a bendingportion61A of theelectrode lead61 are embedded in the black-color resin piece71 such that those portions are surrounded by the black-color resin piece71. The black-color resin piece71 as a whole has an approximately cubic shape.
• In the sixth embodiment, a black-[0088]color front surface71A of the black-color resin piece71 defines back surfaces opposite to the mountingsurface62A of thelead frame62, thesurface63A of theelectrode lead63, and thesurface61A of theelectrode lead61. Therefore in the sixth embodiment, a contrast can be improved.
• (Seventh Embodiment)[0089]
• Next, FIG. 8 shows an LED lamp in a seventh embodiment of the present invention. In the seventh embodiment, an[0090]LED chip82 is mounted on a mountingsurface81A of alead frame81, and theLED chip82 is connected to anelectrode lead96 through aconnection wire88. Theelectrode lead96 bends and extends from the bottom surface to a side surface of aresin body85.
• The[0091]LED chip82 is embedded in a resinconvex lens84. Theconvex lens84 is convex toward the light emitting direction of theLED chip82. The LED lamp, during operation, uses the direction perpendicular to alight emitting surface82A of theLED chip82 as a frontward direction and the direction parallel to the light emitting surface as an upward/downward direction. As shown in the sectional view of FIG. 9, theconvex lens84 is composed of anupper portion91 and alower portion92 in the above-stated upward/downward direction, and theupper portion91 and thelower portion92 abut on each other in an interface plane S51. The interface plane S51 is a plane that is orthogonal to an extension of the light emitting surface82B of theLED chip82 and does not intersect with theLED chip82. The interface plane S51 is upwardly away from a central axis S52 of theLED chip82 by a distance D5 and is upwardly away from theLED chip82. Also, an uppercurved surface91A of theupper portion91 of theconvex lens84 is shaped such that the uppercurved surface91A refracts outgoing rays of light from theLED chip82 more strongly than a lowercurved surface92A of thelower portion92 does. According to the seventh embodiment, therefore, as with the first to sixth embodiments, it becomes possible to prevent the misrecognition that an actuallyunlit LED chip82 is lit, due to incident rays of light from the outside such as afternoon light. Also, the interface plane S51 between theupper portion91 and thelower portion92 of theconvex lens84 is located higher than the central axis S52 by the distance D5, and is located above theLED chip82. According to the seventh embodiment, therefore, it becomes possible to prevent outgoing rays of light from theLED chip82 from being concentrated upon the interface plane S51 so as to prevent generation of an irregular light emitting peak at the front.
• Also in the seventh embodiment, as shown in FIG. 9, the[0092]LED chip82 is disposed at a bottom95A of a cone-shaped hollow95 of theresin body85. Aperipheral wall surface97 serving as a reflection cup of the hollow95 is black surface-treated so as to set light reflectance to 80% or less. Theperipheral wall surface97 with reflectance of 80% or less is shaped such that a diameter thereof is increased toward the light emitting direction of theLED chip82 so that the cone-shaped hollow is broadened toward the end. The black-coloredperipheral wall surface97 restrains outside rays of light having entered theconvex lens84 from being reflected and exiting from theconvex lens84 to the outside. This enables more reliable prevention of misrecognition of an unlit lamp as being lit. Also, in the seventh embodiment, the black surface treatment is applied to set reflectance of theperipheral wall surface97 to 80% or less. This is because reflectance of over 80% does not provide a sufficient reflection inhibition effect.
• The LED lamps as described in the first to the seventh embodiments may be arrayed in matrix form so as to enable implementation of an LED display unit for displaying information such as images, symbols, and letters. According to this LED display unit, it becomes possible to restrain uneven display, increase display quality, and restrain misrecognition due to outside rays of light.[0093]
• (Eight Embodiment)[0094]
• FIG. 13 shows an LED lamp in an eighth embodiment of the present invention seen from a lateral side. In the eighth embodiment, an[0095]LED chip132 is mounted on a plate-shaped mountingportion131A of alead frame131. TheLED chip132 and the mountingportion131A are embedded in aconvex lens133 made of resin. The resinconvex lens133 is convex in the emission direction of rays of light emitted from theLED chip132. Theconvex lens133 has anupper portion135 and alower portion136. The lens surface of theconvex lens133 is composed of an uppercurved surface135A of theupper portion135 and a lowercurved surface136A of thelower portion136.
• The upper[0096]curved surface135A exemplifies a curved surface on one side while the lowercurved surface136A exemplifies a curved surface on the other side.
• An interface plane S131, which is a joint surface between the[0097]upper portion135 and thelower portion136 of theconvex lens133, is orthogonal to an extended surface of alight emitting surface132B of theLED chip132, and extends off the center of thelight emitting surface132B and is located lower by a distance D131 than an exit optical axis J131 of theLED chip132. The interface plane S131 is located below an extended surface of alower end surface132C of theLED chip132.
• The[0098]upper portion135 of the resinconvex lens133 is composed of a firstupper portion137 and a secondupper portion138, and the firstupper portion137 has a first upper curved surface135A1, while the secondupper portion138 has a second upper curved surface135A2.
• An interface plane S132 that is a joint surface between the first[0099]upper portion137 and the secondupper portion138 locates higher by a distance D132 than an exit optical axis J131, and also above an extended surface of anupper end surface132A of theLED chip132.
• The LED lamp, during operation, uses the direction perpendicular to a[0100]light emitting surface132B of theLED chip132 as a frontward direction and the direction parallel to thelight emitting surface132B as an upward/downward direction. During operation, theupper portion135 locates on the upper side while thelower portion136 locates on the lower side. More specifically, in FIG. 13, the direction of an arrow-headed X-axis denotes the upward direction and the direction of an arrow-headed Z-axis denotes an optical axis direction. Also, a Y-axis direction that is perpendicular to the upward direction and the optical axis direction is a lateral direction.
• As shown in FIG. 13, the upper[0101]curved surface135A of theupper portion135 is shaped such that the uppercurved surface135A refracts outgoing rays of light from theLED chip132 more greatly than the lowercurved surface136A positioned axisymmetrically to thesurface135A about the exit optical axis J131 does. More specifically, the uppercurved surface135A of theupper portion135 is in the shape of a curved surface where an incident angle of outgoing rays of light from theLED chip132 is larger than that at the lowercurved surface136A positioned axisymmetrically about the exit optical axis J132.
• Again, in the eighth embodiment, the upper[0102]curved surface135A, which is different in shape from the lowercurved surface136A, is shaped to refract rays of light emitted by theLED chip132 larger than the lowercurved surface136A does. In other words, theconvex lens133 has vertically asymmetric lens curvatures.
• An outside ray of light that comes incident at a shallow angle (as typified by afternoon light) upon the lower[0103]curved surface136A of theconvex lens133 is refracted and reaches an internal location where theLED chip132 is mounted, and then the ray of light is reflected to reach the uppercurved surface135A. This outside ray of light is then steeply refracted by the uppercurved surface135A and emitted toward the lower side. If the outside ray of light comes incident upon the uppercurved surface135A at an incident angle beyond a critical angle, the outside ray of light is totally reflected by the uppercurved surface135A and does not exit from theconvex lens133. The uppercurved surface135A refracts the outgoing rays of light, which are emitted from theLED chip132 and have an identical outgoing angle, more steeply than the lowercurved surface136A does.
• Accordingly, in the present embodiment, if outside rays of light come incident, reflection of the outside rays of light toward the front side is avoidable, and therefore the misrecognition of an unlit diode lamp as being lit can be prevented.[0104]
• Further, in the present embodiment, since the upper[0105]curved surface135A and the lowercurved surface136A are disposed on the upper side and the lower side of the interface plane S131 extending off the center of thelight emitting surface132B, outgoing rays of light are prevented from theLED chip132 from concentrating upon the plane extending through the center of thelight emitting surface132B, thereby enabling prevention of an irregular light emitting peak from being produced at the front. This makes it possible to avoid the phenomenon of rapid decline of luminous intensity only with slight displacement of a view point from the front, and to prevent misrecognition due to incident rays of light from the outside such as afternoon sunlight without, causing uneven display.
• Also in the eighth embodiment, the interface plane S131 between the upper[0106]curved surface135A and the lowercurved surface136A is positioned below the optical axis J131, so that outgoing rays of light are collected more in the downward direction, as compared to the case where the interface plane S131 is positioned on or above the optical axis J131. Therefore, the LED lamp in the eighth embodiment is suitable for use in display unit for displaying information from on high toward underneath viewers, such as, for example, anLED display unit201 for displaying road information such as traffic information as shown in FIG. 20, which has adisplay surface203 oriented in approximately a horizontal direction and supported by apole202 at the height of several meters above the ground. In such a case, a peak of the intensity distribution of outgoing rays of light from theconvex lens133 may be set to, for example, downward 3° where the lateral direction is 0°. More particularly, theupper portion135 of theconvex lens133 of the LED lamp in the eighth embodiment is positioned on the upper side, and thelower portion136 is positioned on the lower side. According to theLED display unit201, it becomes possible to reduce reflection at thedisplay surface203 of sunlight to thereby prevent the misrecognition. It is noted that in theLED display unit201, theconvex lens133 of the LED lamp may be rotated by a specified angle about the optical axis J131, depending on an incident angle of the sunlight upon thedisplay surface203 before being mounted on thedisplay surface203.
• Further in the eighth embodiment, as shown in FIG. 13, the upper[0107]curved surface135A of theupper portion135 of theconvex lens133 has a maximum curvature on the interface plane S132 located higher by a distance D132 (e.g., 2.0 mm) than the optical axis J131. In the eighth embodiment, it becomes possible to collect outgoing rays of light from theLED chip132 to some degree onto the interface plane S132 to thereby regulate distribution of light going in the upward direction.
• Also, the first upper curved surface[0108]135A1 of the uppercurved surface135A has a curvature smaller than that of the second upper curved surface135A2, and is located above the second upper curved surface135A2. In the uppercurved surface135A, the second upper curved surface135A2 makes the transition to the first upper curved surface135A1 at the interface plane S132 where the inclination of the uppercurved surface135A relative to a horizontal plane containing the Y axis and Z axis decreases abruptly. The presence of the first upper curved surface135A1 enables increase of the luminous intensity distribution in the downward direction.
• Next, more detailed description will be given of an example of the configuration of the lens surface of the[0109]convex lens133 in the eighth embodiment.
• The first upper curved surface[0110]135A1 of the uppercurved surface135A constituting a lens surface is specified by the following formula (f1):
• Z²/(9.02)²+x²/(3.015)²=1  (f1)
• In the above formula (f1), a point (x1, z1) in the x-z coordinate plane having an origin P0 at an intersecting point between the optical axis J131 and the[0111]light emitting surface132B of theLED chip132 is set as an origin P1. Here, a point P1 (0, 0) is defined as the origin P1 (x1, z1). In the formula (f1), x denotes an x coordinate (in mm) from the origin P1 (x1, z1), and z denotes a z-coordinate (in mm) from the origin (x1, z1).
• The second upper curved surface[0112]135A2 of the uppercurved surface135A constituting a lens surface is specified by the following formula (f2):
• Z²/(3.42)²+x²/(3.065)²=1   (f2)
• In the above formula (f2), a point (x2, z2) in the x-z coordinate plane having the origin P0 is set as an origin P2. Here, a point P2 (0, 5.52) is defined as the origin P2 (x2, z2). In the formula (f2), x denotes an x-coordinate (in mm) from the origin P2 (x2, z2), and z denotes a z-coordinate (in mm) from the origin P2 (x2, z2).[0113]
• The lower[0114]curved surface136A constituting a lens surface is specified by the following formula (f3):
• Z²/(3.62)²+x²/(3.065)²=1   (f3)
• In the above formula (f3), a point (x3, z3) in the x-z coordinate plane having the origin P0 is set as an origin P3. Here, a point P3 (0, 5.32) is defined as the origin P2 (x3, z3). In the formula (f3), x denotes an x-coordinate (in mm) from the origin P3 (x3, z3), and z denotes a z-coordinate (in mm) from the origin P3 (x3, z3).[0115]
• In the specific example of the configuration of the lens surface in the above embodiment specified by the formulas (f1), (f2), and (f3), the distance D131 is 0.2 mm, and the distance D132 is 2.0 mm. More specifically, at the point 0.2 mm below the optical axis J131, the lower[0116]curved surface136A meets the second upper curved surface135A2. Also at the point 2.0 mm above the optical axis J131, the second upper curved surface135A2 meets the first upper curved surface135A1.
• It is noted that the curvature shape of the first upper curved surface[0117]135A1, the second upper curved surface135A2, and the lowercurved surface136A on a horizontal plane (i.e., a plane parallel to the Y-Z plane) is of an ellipse of which a vertex is an intersection point with a vertical plane that goes through the origin P0, and which is specified by the following formula (f4):
• Z²/(3.62)²+y²/(3.015)²=1   (f4)
• In the above formula (f4), a unit of z-coordinate and y-coordinate is mm.[0118]
• Further, the joints of the lens surface specified by the above formulas (f1) to (f4) are chamfered so as to eliminate sharp corners. In the specific example of the eighth embodiment, it becomes possible to decrease an influence of outside rays of light by, for example, 20%, resulting in an increased light emitting rate from the[0119]LED chip132. Also, use of the first and second upper curved surfaces135A1,135A2 in combination makes it possible to regulate a distribution of outgoing rays of light from theupper portion135 of theconvex lens133.
• (Ninth Embodiment)[0120]
• Next, FIG. 14 shows an LED lamp in a ninth embodiment of the present invention seen from the front side. In the ninth embodiment, two[0121]LED chips142,143 are mounted on a mountingportion141A of alead frame141. These twoLED chips142,143 are connected to respective electrode leads145,146 on both sides of thelead frame141 throughconnection wires147,148.
• The mounting[0122]portion141A, the twoLED chips142,143, and the electrode leads145,146 are embedded in aconvex lens144 made of resin. Theconvex lens144 is convex toward the light emitting direction of the twoLED chips142,143. Theconvex lens144 is composed of anupper portion151 and alower portion152 which abut on each other on an interface plane S142. The interface plane S142 is a plane that is orthogonal to extended surfaces of light emittingsurfaces142B,143B of the LED chips142,143 and does not intersect with theLED chips142,143. The LED lamp, during operation, uses the direction perpendicular to thelight emitting surfaces142B,143B of the LED chips142,143 as a frontward direction and the normal direction to the interface plane S142 as an upward/downward direction.
• In operation, the[0123]upper portion151 is located on the upper side of the interface plane S142 while thelower portion152 is located on the lower side of the interface plane S142.
• The[0124]upper portion151 has an uppercurved surface151A as the one-side curved surface, and thelower portion152 has a lowercurved surface152A as the other-side curved surface. The interface plane S142 is parallel to an optical axis plane S143, which goes through an exit optical axis that is the center of the upward/downward direction of thelight emitting surfaces142B,143B of the twoLED chips142,143, and which is orthogonal to thelight emitting surfaces142B,143B. The optical axis plane S143 is away from the interface plane S142 by a distance D142. As shown in FIG. 14, the interface plane S142 is positioned below theLED chips142,143. The LED chips142,143 are arrayed in a lateral direction that is perpendicular to the optical axis direction and that is also perpendicular to the above-stated upward/downward direction.
• The[0125]upper portion151 of theconvex lens144 includes amaximum thickness portion150 in which a vertical thickness of theupper portion151 is maximal, on an orthogonal plane S146. The orthogonal plane S146 extends across a central axis J152 extends in an optical axis direction between the LED chips142 and143, and intersects with the optical axis plane S143. Thelower portion152 of theconvex lens144 also includes amaximum thickness portion153 in which a vertical thickness of thelower portion152 is maximal, on the orthogonal plane S146.
• The upper[0126]curved surface151A of theupper portion151 and the lowercurved surface152A of thelower portion152 form alens surface144A of theconvex lens144. The uppercurved surface151A of thelens surface144A is a curved surface that refracts outgoing rays of light from the LED chips142,143 larger than the lowercurved surface152A does, and makes the rays of the light exit from thelens surface144A. According to the ninth embodiment, therefore, as with the eighth embodiment, it becomes possible to prevent the misrecognition that an actually unlit LED chip is lit, due to incident rays of light from the outside such as afternoon light.
• Further in the ninth embodiment, the upper[0127]curved surface151A and the lowercurved surface152A are positioned on the upper side and the lower side relative to the interface plane S142 extending off the centers of thelight emitting surfaces142B,143B. Therefore, it becomes possible to prevent outgoing rays of light from the LED chips142,143 from being concentrated upon the plane S143 that goes through the centers of thelight emitting surfaces142B,143B so as to prevent generation of an irregular light emitting peak on the front side. This makes it possible to avoid the phenomenon of rapid decline of luminous intensity only with slight displacement of a view point from the front side, and to prevent the misrecognition due to incident rays of light from the outside, without causing uneven display.
• Also in the ninth embodiment, the interface plane S142 between the upper[0128]curved surface151A and the lowercurved surface152A is positioned below the optical axis plane S143, so that outgoing rays of light are collected in downward direction to more extent, compared with the case where the interface plane S142 is positioned above the optical axis plane S143. Therefore, the LED lamp in the eighth embodiment is suitable for use in display units for displaying information from on high toward underneath viewers, such as, for example, anLED display unit201 for displaying road information such as traffic information as shown in FIG. 20, which has adisplay surface203 oriented in approximately a horizontal direction and supported by apole202 at the height of several meters above the ground. In such a case, a peak of the intensity distribution of outgoing rays of light from theconvex lens144 may be set to, for example, downward 3° where the lateral direction is 0°.
• Also in the ninth embodiment, the upper[0129]curved surface151A of theupper portion151 is composed of a first upper curved surface151A1 and a second upper curved surface151A2. The first upper curved surface151A1 and the second upper curved surface151A2 abut on each other on an interface plane S145. The first upper curved surface151A1 is positioned higher than the second upper curved surface151A2 relative to the interface plane S145. The interface plane S145 is parallel to the optical axis plane S143 and the interface plane S142. Also, the interface plane S145 is positioned higher than the optical axis plane S143 by a distance D143, and does not intersect with thelight emitting surfaces142B,143B.
• Further, in the ninth embodiment, the upper[0130]curved surface151A of theupper portion151 of theconvex lens144 has a maximum curvature at the interface plane S145 located higher by a distance D143 (e.g., 2.0 mm) than the optical axis plane S143. Consequently in the ninth embodiment, it becomes possible to collect outgoing rays of light from the LED chips142,143 to some degree onto the interface plane S145 to thereby regulate distribution of the upward light.
• The first upper curved surface[0131]151A1 of the uppercurved surface151A has a curvature smaller than that of the second upper curved surface151A2, and is located above the second upper curved surface151A2. In the uppercurved surface151A, the second upper curved surface151A2 makes the transition to the first upper curved surface151A1 at the interface plane S145 where the inclination of the uppercurved surface135A relative to the optical axis plane (a horizontal plane) S143 decreases abruptly. The presence of the first upper curved surface151A1 enables increase of the luminous intensity distribution in the downward direction.
• Further, in the ninth embodiment, for example, the[0132]LED chip142 may be designed as a red-color LED and theLED chip143 may be designed as a green-color LED so as to implement a multicolor-lighting LED lamp. It should be understood that a lighting color combination of theLED chips142 and143 is not limited to the combination of red-color and green-color, but a combination of red-color and blue-color and a combination of yellow-color and green-color are also applicable. Giving the same color to the twoLED chips142,143 enables increase of luminance. Although there are provided two LED chips in the ninth embodiment, there may be provided more than two LED chips.
• (Tenth Embodiment)[0133]
• Next, FIG. 15 shows a tenth embodiment. In the tenth embodiment, the[0134]convex lens144 made of resin in the above-described ninth embodiment is replaced with a convex lens made of epoxy resin which is mixed with a pigment that transmits rays of light having specified wavelengths (e.g., a wavelength corresponding to green-color and a wavelength corresponding to a red-color) and attenuates rays of light having wavelengths other than the specified wavelengths. In this case, if, for example, theLED chip142 is designed to emit a red-color light, and theLED chip143 is designed to emit a green-color light, it becomes possible to attenuate practically unnecessary emitted light, thereby enabling further increase of display quality, and also inhibiting re-reflection of rays of light entering theconvex lens144 from the outside.
• Alternatively, the epoxy resin that forms the[0135]convex lens144 may be mixed with a pigment having a light absorption band in the wavelengths other than the wavelength corresponding to green-color and the wavelength corresponding to red-color. In this case, unnecessary rays of light other than green-color and red-color lights are absorbed and attenuated by the convex lens, which increases display quality. It is noted that the materials of theconvex lens144 may be resin other than the epoxy resin. If the pigment cannot be mixed in the resin, the pigment may be applied to the surface of theconvex lens144. Further, it is also possible to cover the surface of theconvex lens144 with a cover with the pigment mixed therein.
• (Eleventh Embodiment)[0136]
• Next, FIG. 16 shows an LED lamp in an eleventh embodiment of the present invention. The eleventh embodiment is different from the above-described ninth embodiment only in that instead of the[0137]lead frame141 and the electrode leads145,146 of the ninth embodiment in FIG. 14, alead frame162 and electrode leads163,161 are provided.
• In the eleventh embodiment, black surface treatment is applied to a mounting[0138]surface162A of thelead frame162 so as to make light reflectance of the mountingsurface162A 80% or less. The black surface treatment is also applied tosurfaces163A,161A of the electrode leads163,161 so as to make light reflectance of thesurfaces163A,161A 80% or less.LED chips142,143 are mounted on the mountingsurface162A, and theLED chip142 is connected to thesurface163A of theelectrode lead163 through aconnection wire147. TheLED chip143 is connected to thesurface161A of theelectrode lead161 through aconnection wire148.
• In the eleventh embodiment, light reflectance of the mounting[0139]surface162A of thelead frame162 is set to 80% or less, and light reflectance of thesurfaces163A,161A of the electrode leads163,161 is set to 80% or less, which makes it possible to restrain outside rays of light having entered theconvex lens144 from reflecting on the mountingsurface162A and thesurfaces163A,161A. Accordingly, it becomes possible to restrain outside rays of light incident upon theconvex lens144 from exiting from theconvex lens44, and to ensure prevention of misrecognition of an unlit diode lamp as being lit. As described above, in the eleventh embodiment, black surface treatment is applied to set reflectance of the mountingsurface162A of thelead frame162 and thesurfaces163A,161A of the electrode leads163,161 to be 80% or less. This is because reflectance over 80% does not provide a sufficient reflection inhibition effect.
• (Twelfth Embodiment)[0140]
• Next, FIG. 17 shows an LED lamp in a twelfth embodiment of the present invention. The twelfth embodiment is different from the above-described eleventh embodiment only in the point that in a position retreated by a specified distance from the[0141]surfaces162A,163A and161A of thelead frame162 and of the electrode leads163,161 in the eleventh embodiment of FIG. 16 in a direction opposite from the light emitting direction, there is provided a black-color resin piece171 that extends from the inside of theconvex lens144 beyond itsbottom surface24C to the outside.
• A[0142]neck portion162B of thelead frame162, a bendingportion163B of theelectrode lead163, and a bendingportion161B of theelectrode lead161 are embedded in the black-color resin piece171 such that those portions are surrounded by the black-color resin piece171. The black-color resin piece71 as a whole has an approximately cubic shape.
• In the twelfth embodiment, a black-[0143]color front surface171A of the black-color resin piece171 defines back surfaces opposite to the mountingsurface162A of thelead frame162, thesurface163A of theelectrode lead163, and thesurface161A of theelectrode lead161. Therefore in the twelfth embodiment, a contrast can be improved.
• (Thirteenth Embodiment)[0144]
• Next, FIG. 18 shows an LED lamp in a thirteenth embodiment of the present invention. In the thirteenth embodiment, an[0145]LED chip182 is mounted on a mountingsurface181A of alead frame181, and theLED chip182 is connected to anelectrode lead196 through aconnection wire188. Theelectrode lead196 bends and extends from the bottom surface to a side surface of aresin body185.
• The[0146]LED chip182 is embedded in a resinconvex lens184. Theconvex lens184 is convex toward the light emitting direction of theLED chip182. The LED lamp, during operation, uses the direction perpendicular to alight emitting surface182A of theLED chip182 as a frontward direction and the direction parallel to thelight emitting surface182A as an upward/downward direction. More specifically, in FIG. 18, the direction of an arrow-headed Z-axis denotes a frontward direction, the direction of an arrow-headed X-axis denotes an upward direction, and the direction of a Y-axis denotes a lateral direction. In this embodiment, theconvex lens184 is manufactured by transfer molding.
• As shown in the sectional view of FIG. 19, in the thirteenth embodiment, the[0147]convex lens184 is composed of anupper portion195 and alower portion196 relative to the above-stated upward/downward direction, and theupper portion195 and thelower portion196 abut on each other in an interface plane S191. The interface plane S191 is a plane that is orthogonal to an extended surface of the light emitting surface182B of theLED chip182 and does not intersect with theLED chip182.
• The interface plane S191 is downwardly away from a central axis J191 of the[0148]light emitting surface182A of theLED chip182 by a distance D191 and is downwardly away from theLED chip182. Also, an uppercurved surface195A of theupper portion195 of theconvex lens184 is shaped so as to refract outgoing rays of light from theLED chip182 more than a lowercurved surface196A of thelower portion196 does. According to the thirteenth embodiment, therefore, as with the eighth to twelfth embodiments, during operation, it becomes possible to prevent the misrecognition that anLED chip182 actually unlit is lit, due to incident rays of light from the outside such as afternoon light. Also, the interface plane S191 between theupper portion195 and thelower portion196 of theconvex lens184 is located lower than the central axis J191 by a size D191 (e.g., 0.2 mm), and is located below theLED chip182. According to the thirteenth embodiment, therefore, it becomes possible to prevent outgoing rays of light from theLED chip182 from being concentrated upon the interface plane S191 so as to prevent generation of an irregular light emitting peak at the front.
• Also, in the thirteenth embodiment, as shown in FIG. 19, the[0149]LED chip182 is disposed on a mountingsurface181A forming abottom surface205A of a cone-shaped hollow205 of theresin body185. Aperipheral wall surface207 of the hollow205 serving as a reflection cup is black surface-treated so as to set light reflectance to 80% or less. Theperipheral wall surface207 constituting the reflection cup with reflectance of 80% or less is shaped such that a diameter thereof is increased toward the light emitting direction of theLED chip182 so that the cone-shaped hollow is broadened toward the end. The black-coloredperipheral wall surface207 restrains outside rays of light incident having entered theconvex lens184 from being reflected and exiting from theconvex lens184 to the outside. That is, it is possible to inhibit a phenomenon that the reflection cup glows due to rays of light incident from the outside. This enables more reliable prevention of misrecognition of an unlit lamp as being lit. It is noted that in the thirteenth embodiment, the black surface treatment is applied to set reflectance of theperipheral wall surface207 to 80% or less. This is because reflectance over 80% does not provide a sufficient reflection inhibition effect.
• Also, in the thirteenth embodiment, like the eighth embodiment, the interface plane S191 between the upper[0150]curved surface195A and the lowercurved surface196A is positioned below an optical axis J191, so that outgoing rays of light are collected in downward direction, as compared with the case where the interface plane S191 is positioned on or above the optical axis J191. Therefore, the LED lamp in the thirteenth embodiment is suitable for use in theLED display unit201 for displaying road information such as traffic information as shown in FIG. 20. According to theLED display unit201, it becomes possible to reduce reflection of sunlight at thedisplay surface203 and thereby prevent the misrecognition.
• Further in the thirteenth embodiment, the upper[0151]curved surface195A of theupper portion195 of theconvex lens184 has a maximum curvature on the interface plane S192 located higher by a distance D192 (e.g., 2.0 mm) than the optical axis J191. In the thirteenth embodiment, it becomes possible to collect outgoing rays of light from theLED chip182 to some degree onto the interface plane S192 to thereby regulate distribution of upward light.
• Also, a first upper curved surface[0152]195A1 of the uppercurved surface195A has a curvature smaller than that of a second upper curved surface195A2, and is located above the second upper curved surface195A2. In the uppercurved surface195A, the second upper curved surface195A2 makes the transition to the first upper curved surface195A1 at the interface plane S192 where the inclination of the uppercurved surface195A relative to a horizontal plane containing the Y axis and Z axis decreases abruptly. The presence of the first upper curved surface195A1 enables increase of the luminous intensity distribution in the downward direction.
• It should be understood that in the first to thirteenth embodiments, in addition to epoxy resin, desired transparent resin may be adopted as resin materials for the convex lens. Although in the eighth to thirteenth embodiments, the upper curved surface of the convex lens is composed of the first and second two upper curved surfaces, the upper curved surface may be composed of three or more curved surfaces different in shape. Further, the lower curved surface of the convex lens may be composed of a plurality of curved surfaces having different shapes to regulate the outgoing direction of rays of light emitted from the curved surface of the convex lens.[0153]
• The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.[0154]

Claims (15)

What is claimed is:

1. A light emitting diode lamp comprising:

at least one light emitting diode chip; and

a convex lens through which rays of light emitted from the at least one light emitting diode chip pass, wherein

the convex lens has two different curved surfaces on both sides of a plane orthogonal to a light emitting surface of the light emitting diode chip or to an extension of the light emitting surface and extending off a center of the light emitting surface, and

one of the curved surfaces of the convex lens refracts outgoing rays of light from the light emitting diode chip more greatly than the other of the curved surfaces of the convex lens does.

2. The light emitting diode lamp as defined inclaim 1, wherein

the plane extending off a center of the light emitting surface is orthogonal to the extension of the light emitting surface of the light emitting diode chip and does not intersect with the light emitting diode chip.

3. The light emitting diode lamp as defined inclaim 1, comprising more than one light emitting diode chips, which are arrayed in one direction.

4. The light emitting diode lamp as defined inclaim 1, wherein

said at least one light emitting diode chip is molded by resin having a light absorption band in wavelengths other than a peak wavelength of rays of light emitted by the light emitting diode chip, and the resin constitutes the convex lens.

5. The light emitting diode lamp as defined inclaim 1, wherein

said at least one light emitting diode chip is mounted on a black surface-treated lead frame.

6. The light emitting diode lamp as defined inclaim 1, further comprising

a reflection cup surrounding at least a part of a periphery of the light emitting diode chip, and an inner peripheral surface of the reflection cup is black surface-treated.

7. The light emitting diode lamp as defined inclaim 1, wherein

black-colored resin is mounted on a lead frame on which the light emitting diode chip is mounted, the black-colored resin being positioned behind the light emitting diode chip.

8. A light emitting diode display unit comprising the light emitting diode lamp as defined inclaim 1.

9. The light emitting diode lamp as defined inclaim 1, wherein

at least one of said two curved surfaces of the convex lens comprises a plurality of curved surfaces different in shape.

10. The light emitting diode lamp as defined inclaim 9, wherein

the plurality of curved surfaces include a curved surface on one side and a curved surface on the other side of a plane that is orthogonal to the extension of the light emitting surface of the light emitting diode chip and that does not intersect with the light emitting diode chip.

11. The light emitting diode lamp as defined inclaim 9, comprising more than one light emitting diode chips, which are arrayed in one direction.

12. The light emitting diode lamp as defined inclaim 9, wherein

the light emitting diode chips are molded by resin having a light absorption band in wavelengths other than a plurality of wavelength peaks of rays of lights emitted by the light emitting diode chips, and the resin constitutes the convex lens.

14. The light emitting diode lamp as defined inclaim 9, further comprising

a reflection cup surrounding at least a part of a periphery of the light emitting diode chip, and an inner peripheral surface of the reflection cup is black surface-treated.

15. The light emitting diode lamp as defined inclaim 9, wherein

black-colored resin is mounted on a lead frame on which the light emitting diode chip is mounted, the black-colored resin being positioned behind the light emitting diode chip.

16. A light emitting diode display unit comprising the light emitting diode lamp as defined inclaim 9.

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