Disclosure of Invention
The embodiment of the invention aims to provide a micro-projection device so as to improve the quality of a projection picture and the utilization rate of laser. The specific technical scheme is as follows:
The embodiment of the invention provides a micro-projection device, which comprises a laser diode, a diaphragm, a collimating lens, a dichroic prism assembly, a trapezoid prism, a micro-electromechanical system and an imaging lens;
the diaphragm is positioned between the laser diode and the collimating lens;
the trapezoidal prism is positioned between the dichroic prism assembly and the microelectromechanical system;
The laser emitted by the laser diode sequentially passes through the diaphragm, the collimating lens, the dichroic prism assembly, the trapezoidal prism, the micro-electromechanical system and the imaging lens to obtain a projection picture, wherein the diaphragm is used for removing stray light of the laser, and the trapezoidal prism is used for compressing the laser.
Optionally, the fast axis direction of the laser diode is a horizontal direction, and the slow axis direction is perpendicular to the fast axis direction.
Optionally, a circular through hole is formed in the middle of the diaphragm.
Optionally, the diaphragm is square in shape.
Optionally, the trapezoidal prism is an achromatic lens.
Optionally, the placement angle of the trapezoidal prism is 50 ° to 70 °.
Optionally, the imaging lens includes an adjusting unit, and the adjusting unit is used for adjusting the projection distance and the size of the projection picture.
The micro-projection device comprises a laser diode, a diaphragm, a collimating lens, a dichroic prism assembly, a trapezoidal prism, a micro-electromechanical system and an imaging lens, wherein the diaphragm is arranged between the laser diode and the collimating lens, the trapezoidal prism is arranged between the dichroic prism assembly and the micro-electromechanical system, laser emitted by the laser diode sequentially passes through the diaphragm, the collimating lens, the dichroic prism assembly, the trapezoidal prism, the micro-electromechanical system and the imaging lens to obtain a projection picture, the diaphragm is used for removing stray light of the laser, and the trapezoidal prism is used for compressing the laser.
By adopting the micro-projection device provided by the embodiment of the invention, stray light can be reduced through the diaphragm, and laser is compressed through the trapezoidal prism to reduce light spots, so that the quality of a projection picture and the laser utilization rate are improved. Of course, it is not necessary for any one product or method of practicing the invention to achieve all of the advantages set forth above at the same time.
Detailed Description
The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.
The embodiment of the invention provides a micro-projection device, as shown in fig. 1, which comprises a laser diode 1.1, a diaphragm 1.2, a collimating lens 1.3, a dichroic prism component 1.4, a trapezoid prism 1.5, a micro-electromechanical system 1.6 and an imaging lens 1.7. Wherein the diaphragm 1.2 is arranged between the laser diode 1.1 and the collimating lens 1.3; the trapezoidal prism 1.5 is located between the dichroic prism assembly 1.4 and the microelectromechanical system 1.6; the laser emitted by the laser diode 1.1 sequentially passes through a diaphragm 1.2, a collimating lens 1.3, a dichroic prism component 1.4, a trapezoid prism 1.5, a micro-electromechanical system 1.6 and an imaging lens 1.7 to obtain a projection picture; the diaphragm 1.2 is used for removing stray light of laser, and the trapezoid prism 1.5 is used for compressing the laser.
In an embodiment of the invention, the number of groups of laser diodes 1.1 may be one or more, each group typically comprising three laser diodes, e.g. three laser diodes may be diodes emitting red, green and blue monochromatic light, respectively. The diaphragm 1.2 may be a square baffle with a pupil in the middle, and the diaphragm 1.2 is mainly used for removing or reducing stray light. The collimator lens 1.3 can convert the incident laser light into parallel laser light. The dichroic prism assembly 1.4 is made by gluing a plurality of lenses with different refractive indices. The trapezoidal prism 1.5 is a lens in the shape of a trapezoid, and is mainly used for compressing wider laser light into thinner laser light. The microelectromechanical system 1.6 is a micro-device comprising a microsensor, a micro-actuator and a micromechanical structure equal to one. Imaging lens 1.7 typically comprises an acromatic lens which may reduce chromatic aberration in the projected picture.
The prior art micro-projection device typically only comprises a photodiode 1.1, a collimator lens 1.3, a dichroic prism assembly 1.4, a micro-electro-mechanical system 1.6 and an imaging lens 1.7.
By adopting the micro-projection device provided by the embodiment of the invention, stray light can be reduced by adding the diaphragm 1.2, and the quality of a projection picture can be improved after the stray light is reduced; laser can be compressed to reduce light spots by adding the trapezoid prism 1.5, so that the quality of a projection picture and the laser utilization rate are improved.
Alternatively, as an implementation manner of the embodiment of the present invention, the fast axis direction of the laser diode 1.1 is a horizontal direction, and the slow axis direction is perpendicular to the fast axis direction. The placement direction of the laser diode 1.1 is shown in fig. 2 and 3, the connecting line between the two pins of the laser diode is in the vertical direction, the horizontal direction is the same as the fast axis direction of the laser diode, and the vertical direction is the same as the slow axis direction of the laser diode. Fig. 2 is a right side view of the laser diode, and fig. 3 is a top view of the laser diode.
In the embodiment of the invention, the laser emitted by the laser diode is considered to generally comprise a fast axis direction and a slow axis direction, wherein the fast axis direction refers to a direction with a larger laser divergence angle, and the slow axis direction refers to a direction with a smaller laser divergence angle. In this embodiment, the fast axis direction of the laser diode 1.1 is a horizontal direction, i.e., the fast axis direction of the laser diode 1.1 is placed horizontally, and the slow axis direction of the laser diode 1.1 is placed vertically. The placement direction of the laser diode in this example is opposite to that of the prior art.
In the scheme provided by the embodiment of the invention, the fast axis direction of the laser diode is set as the horizontal direction, and the slow axis direction is perpendicular to the fast axis direction. Therefore, the diffuse light in the projection picture can be reduced, and the design difficulty of the imaging lens is reduced.
Alternatively, as an implementation manner of the embodiment of the invention, a circular through hole is arranged in the middle of the diaphragm 1.2, as shown in fig. 4.
In the embodiment of the invention, the middle part of the diaphragm 1.2 is provided with the circular through hole, laser can reach the collimating lens 1.3 through the circular through hole, and the degree of stray light in the laser can be removed by the diaphragm 1.2 by arranging the diameter of the circular through hole.
Alternatively, as an implementation of the embodiment of the invention, the diaphragm 1.2 has a square shape.
In the embodiment of the invention, the diaphragm 1.2 is square, as shown in fig. 3, so that the diaphragm can be conveniently fixed and assembled.
Alternatively, as one implementation of an embodiment of the invention, the trapezoidal prism 1.5 is an achromat.
In the embodiment of the invention, the trapezoidal prism 1.5 is an achromatic lens, and the achromatic lens is adopted, so that the chromatic aberration of laser can be reduced, and the imaging quality of a projection picture can be improved.
Alternatively, as an implementation manner of the embodiment of the present invention, the placement angle of the trapezoidal prism 1.5 is 50 ° to 70 °, as shown in fig. 5.
In the embodiment of the present invention, when the trapezoidal prism 1.5 is assembled, assuming that the laser is incident to the trapezoidal prism 1.5 in the horizontal direction, the placement angle of the trapezoidal prism (i.e., Φ in fig. 5) is generally set to 50 ° < Φ <70 °, so that the laser can be better compressed, and the compression rate of the laser can be improved. After the laser is compressed, the light utilization rate can be improved, the assembly tolerance of the micro-projection device is improved, and the assembly efficiency can be improved when the micro-projection device is produced.
Optionally, as an implementation manner of the embodiment of the present invention, the imaging lens 1.7 includes an adjusting unit, and the adjusting unit is used for adjusting the projection distance and the size of the projection screen.
In the embodiment of the invention, the imaging lens 1.7 adopts a lens with larger projection ratio, and the imaging lens 1.7 comprises an adjusting unit, and the projection distance, the size of a projection picture and the quality of the projection picture can be adjusted through the adjusting unit.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a device or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such device or apparatus. In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.