US20040197243A1 - Air treatment apparatus and methods - Google Patents

Abstract

A multi-function air treatment apparatus includes a photo-ionizing assembly and a negative ion generator. The photo-ionizing assembly emits a predetermined wavelength of light that produces ozone when it impinges upon air. When a portion of the light impinges on a target material, radicals and ions that bond with and reduce some of volatile organic compounds in the air are produced. The negative ion generator produces negative ions and a radiating negative electrostatic field from an outer high dielectric surface by an electrical charge applied to an enclosed conductive inner surface.

Description

BACKGROUND
• This invention relates to a new air treatment apparatus and methods for treatment of air.[0001]
• Air treatment, i.e., the process of treating air to remove undesirable materials, is of great interest as advances in research continue to suggest that breathing purer air has tangible health benefits.[0002]
• One known type of air treatment, referred to as air ionization or electron generation, involves using a source of electricity to produce a charge and generate negative ions. Contaminants suspended in air, such as dust, smoke and pollen, are usually made up of small positively-charged particles. The earth, buildings and other large objects are also positively charged, and thus tend to repel these particles, which keeps them in suspension. Negative ions are beneficial because they combine with the positive particles and neutralize them, and the resulting combinations fall to the earth or floor under the action of gravity because they are heavier than air. As a result, the “ionized” air has fewer suspended particles.[0003]
• Most conventional air ionizers use corona discharge to produce a charge on a surface to generate negative ions. Corona discharge devices involve high voltages and may have a high capacitance, so the user's inadvertent contact with a charged collector surface may lead to an undesirable shock.[0004]
• Another known type of air treatment called photo-ionization involves producing ozone by subjecting the oxygen in air to ultraviolet light at a known wavelength (about 185 nm). Ozone is an effective oxidizer of organic substances, including bacteria, algae, mildew and mold, and helps to eliminate odor.[0005]
• It would be desirable to provide an apparatus that would allow for treatment of air by negative ionization and photo-ionization in a single unit. It would also be desirable to provide for treatment of volatile organic compounds (VOCs), which are not generally susceptible to ozone oxidation.[0006]
DESCRIPTION OF DRAWINGS
• FIGS. 1 and 2 are front and rear perspective views, respectively, of one implementation of a new air treatment unit.[0007]
• FIG. 3 is a sectional view in elevation of the air treatment unit of FIG. 1, viewed along a line at arrows[0008]3-3 in FIG. 1.
• FIG. 4 is an exploded front perspective view of a housing of the air treatment unit of FIG. 1.[0009]
• FIG. 5 is an exploded assembly view of components within the housing of the air treatment unit of FIG. 1.[0010]
• FIG. 6 is a view of a lower end of an inner tray shown in FIG. 5 assembled with a bulb.[0011]
• FIG. 7A is a top view of a modified tray, FIG. 7B is a slightly enlarged end view showing a bulb within the modified tray, and FIG. 7C is a slightly enlarged side view of the modified tray.[0012]
DETAILED DESCRIPTION
• In a new air treatment unit, ambient air, such as air within a living space, is treated to make it more healthy to breathe.[0013]
• According to one aspect of the new air treatment unit, a negative ion generation unit that creates negative ions is provided together with a photo-ionizer. The negative ion generator has an exposed outer surface that is a high dielectric, i.e., substantially nonconductive, and an enclosed inner conductive surface that becomes charged. Negative ions generated at the outer surface are transferred to air via a negative electrostatic field.[0014]
• In specific implementations, a power supply that supplies power to the negative electron generator overcomes the bound charges and is self-limiting.[0015]
• The photo-ionizer or photo-ionizing assembly has a light source that emits ultraviolet light. When oxygen in air is subjected to the ultraviolet light, the oxygen forms ozone.[0016]
• According to another aspect, some of the ultraviolet light produced by light source is caused to strike a target material. The target material includes a catalyst that causes peroxide radicals and super-oxide ions to be produced. The peroxide radicals and super-oxide ions react with VOCs in air and reduce them. Also, because this portion of the ultraviolet light is used to form peroxide radicals and super-oxide ions, and not to produce ozone, the overall production of ozone, which can be an irritant in high quantities, is regulated.[0017]
General
• As shown for one implementation in FIG. 1, an[0018]air treatment unit10 has abase12 and a generallyfrustoconical housing14 extending upwards from thebase12. Thehousing14 tapers in diameter from itslower end15aadjacent thebase12 to anupper end15bat thetop surface16. Thetop surface16 slopes upwardly from afront side17a, which is shown in FIG. 1, to arear side17b, which is shown in FIG. 2.
• Referring to the cross-section of the[0019]air treatment unit10 shown in FIG. 3, the assembledbase12 andhousing14 define a generally enclosedinterior18. Air enters the interior, circulates therein and eventually exits as shown by the arrows. Therear side17bhas louver openings formed therein that are arranged in an upperair inlet portion20 and a lowerair outlet portion22. Openings24 (FIGS. 1 and 2) between thebase12 and thelower end15aof thehousing14, as well as a gap26 (FIGS. 1 and 3) in thetop surface16, also serve as additional air outlet openings.
• A[0020]fan28 is positioned within theinterior18 adjacent theair inlet portion20 to draw air into and generate an air flow through thehousing14. Air within the housing flows upwardly and around a photo-ionization assembly34. Ultraviolet light from the photo-ionization assembly34 causes oxygen in the air to form ozone.
• In operation, which is described below in greater detail, a substantial portion of any given volume of air flowing through the[0021]housing14 is treated by (1) neutralizing positively charged particles through their interaction with the negative ions (which also occurs in surrounding air outside the housing) and (2) oxidation (through the production of ozone by photo-ionization). Optionally, photo-ionization may also include the production of certain radicals and ions (through ultraviolet light striking a target) that reduce VOCs, as is also described below.
Construction
• FIG. 5 is an exploded assembly view showing the[0022]base12 and the components within thehousing14.
• The[0023]negative ion generator32 is a hollow, generally cylindrical structure that tapers slightly from its open lower end to its closed upper end. The lower end is received within thebase12. An upper surface of thebase12 and aninner surface59 of thenegative ion generator32 together define a chamber therein. Thenegative ion generator32 is formed of a high dielectric material, such as melamine, and theouter surface30 is therefore substantially non-conductive. Theinner surface59 is made to be conductive, e.g., as through application of a coating of graphite.
• A[0024]mounting member36 has amounting plate38 positioned above the negative ion generator32 (FIG. 3) and spaced apartlegs40 that are attached to thebase12 with fasteners. In the assembledunit10, thelegs40 are positioned adjacent but slightly spaced from theouter surface30 of thenegative ion generator32 as shown in FIG. 3 to allow air circulation.
• A[0025]support member42 is attached at a rear side of themounting plate38, e.g., with fasteners. Thefan28 is coupled to anupright portion44 of thesupport member42 with fasteners. Anangled portion46, which is cantilevered from theupright portion44, provides a support for the photo-ionization assembly34.
• The photo-ionizing[0026]assembly34 includes a tray (having anouter tray48, aninner tray50 nested within theouter tray48 and a tray end52) and afluorescent bulb90.Apertures53a,53band53cin theinner tray50,outer tray48 andangled portion46, respectively, provide for increased air flow into and around theionization assembly34. An electrical connection, e.g., a socket (not shown), for thebulb90 is provided on theangled portion46 adjacent a lower end of the tray.
• The[0027]fluorescent bulb90, which produces ultraviolet light, typically has twoceramic ends91a,91band a substantially cylindricaltransparent lighting surface92 between the twoends91a,91b. Theend91ahas electrical terminals for establishing an electrical connection.
• When assembled, the ends[0028]91a,91bof thebulb90 are received withinopenings93a,93bin theinner tray50, respectively, with theend91aalso extending through anopening94ain theouter tray48. When assembled, thelighting surface92 of thebulb90 is spaced from theinner tray50.
• Optionally, an[0029]inner surface51 of theinner tray50 may be provided with a target material. In a specific implementation, the target material is provided as a coating on theinner surface51, and the coating is applied to substantially all of theinner surface51. If the inner tray includes anoptional coil95 as shown in FIGS. 7A, 7B and7C or a similar mesh or screen-like structure, thecoil95 or the structure may also be provided with the target material.
• FIGS. 7A, 7B and[0030]7C show an implementation of theinner tray50 is with theoptional coil95 extending between theopenings93a,93b. Thecoil95 is configured of a series of spaced rings each having an opening sized to receive the installedbulb90, yet remain spaced from thelighting surface92. FIG. 7B shows theend91areceived within the opening93aand thecoil95 radially spaced from thelighting surface92. Further details regarding the coating are described below.
• Referring to FIG. 4, a generally[0031]elliptical opening54 is defined in theupper surface16 of thehousing14. Alens56, which is formed of a translucent polycarbonate material, is fitted with a slightly smalleropaque lens center58 and received within theopening54. Thelens56 hasapertures60 extending through to the interior18 of thehousing14. Air can exit the interior18, pass through theapertures60, and exit thehousing14 via thegap26 between thelens56 and thelens center58. As an added feature, if thelens56 is formed of a translucent or transparent material, thelens56 may be lit by thebulb90 during operation of theunit10 and appear as an elliptical ring.
• An[0032]opening62 sized for thetray end52 is defined in thehousing14 above theair inlet portion20. Theopening62 allows the photo-ionization assembly to be slidably removed from or inserted into the unit10 (e.g., to inspect and/or replace the bulb90) without disassembling thehousing14 and thebase12, which requires more time and effort, and may expose other components to potential damage.
Electrical Circuit
• The[0033]air treatment unit10 is designed to operate on normal household 110 V power supplied through apower cord80. Apower switch82 allowing the unit to be turned “ON” or “OFF” is positioned in arecess84 on therear side17bof thehousing14.
• Power is fed to the[0034]power supply86, which is shown in FIG. 5. Theair treatment unit10 operates at a substantially constant voltage. Thepower supply86 provides power to thefan28, thenegative ion generator32 and aballast88 via conventional wiring, which has been omitted for clarity.
• The electrical connection from the[0035]power supply86 to thenegative ion generator32 is a single lead from the negative side of the power supply extending through theouter surface30 to theinner surface59, which supplies about 20,000 volts at 20 kHz to create the negative charge on the conductiveinner surface59 and eliminate the bound charges on the surrounding dielectrics. The supplied power is sufficient to provide a negative charge equivalent of at least 10,000 volts.
• The electrical connection between the[0036]power supply86 andnegative ion generator32 is also self-limiting in that as the electrostatic field adjacent thenegative ion generator32 decreases from a positive value to zero, less power will be supplied so that fewer electrons will be generated. Thus, the self-limiting aspect of thepower supply86 prevents a high negatively charged environment from developing, which would tend to keep particles suspended, rather than allowing them to settle as desired.
• In one specific implementation, the[0037]power supply86 includes a feedback loop with a limiting output resistor such that the voltage supplied to the negative ion generator decreases as the electrostatic field decreases from a positive value to zero.
• The[0038]ballast88, which is connected to thefluorescent bulb90, limits the current supplied to thebulb90 and provides an inductive “kick” to initiate ionization of thebulb90.
• In a specific implementation, suitable electrical components are as follows:[0039]
• Power supply[0040]86: Collmer Semiconductor Series2073 with custom features
• Fan[0041]28: Pelonis Model No. PM8025-7 AC Series Fan (80 mm sq.×25 mm)
• Ballast[0042]88: Robertson Transformer (now Robertson Worldwide) Catalog No. SSGPH287 P magnetic ballast
• Bulb[0043]90: Light Sources Inc. No. GPH118T5VH/4 single-ended 4-pin germicidal bulb.
Operation
• In photo-ionization, ultraviolet light at a wavelength of 185 nm striking oxygen in air will create ozone. The flow rate of the air past the[0044]bulb90, as well as the wavelength and intensity of the light, can be varied to produce ozone at a desired rate. In some implementations, a germicidal light source is used, in which case thebulb90 emits ultraviolet light at a wavelength effective to kill microorganisms (254 nm), as well as at 185 nm.
• Although ozone is an effective oxidizer, other approaches to reducing airborne VOCs produce even better results. In photocatalytic oxidation, VOCs that have been adsorbed from air onto a catalyst surface in the air flow are oxidized by peroxide radicals and super-oxide ions. These peroxide radicals and super-oxide ions may be created by causing ultraviolet light to strike a target material. Photocatalytic oxidation is desirable because VOCs are significantly reduced, rather than being simply captured (e.g., by filtering), which requires their subsequent removal.[0045]
• Photocatalytic oxidation may be combined with ozonation such that light from the same light source produces ozone as well as the peroxide radicals and super-oxide ions. Photocatalytic methods and apparatus are disclosed in U.S. patent application Ser. No. ______, which was filed on Jul. 12, 2000 under the title “Air Treatment Apparatus” and names Ronald G. Fink as the inventor, and which is incorporated herein by reference.[0046]
• In the[0047]air treatment unit10, theinner surface51 of theinner tray52 can be coated or painted with a target material containing at least 10% titanium dioxide by weight. In specific implementations, the target material may also be formulated as 10-30% titanium dioxide, 0-30% silver and 0-30% copper, by weight. Periodic reapplication of the coating may be required.
• As can be seen from FIGS. 5 and 6, the[0048]inner surface51 is shaped and positioned such that it is directly opposite thelighting surface92 of thebulb90 over substantially its entire length and over more than half of its circumference. Specifically, theinner surface51 is positioned such that it is opposite a firstcircumferential portion97aof approximately 210°, with an adjoiningsecond portion97bbeing defined as the remaining approximately 150°. Ultraviolet light emitted in straight rays (i.e., radially) from thefirst portion97ais directed toward theinner surface51, and the portion thereof that reaches theinner surface51 causes the target material to produce peroxide radicals and super-oxide ions. Ultraviolet light emitted through thesecond portion97bnormally does not impinge upon the inner surface51 (and thus does not impinge upon the target material), and therefore this portion of light may generate ozone but not the peroxide radicals and super-oxide ions.
• It can be seen that varying the proportion of ultraviolet light that strikes the target material relative to the portion that does not strike the target material allows regulation of the production of ozone. For example, referring to the implementation of the[0049]inner tray50 with thecoil95 as shown in FIGS. 7A, 7B and7C, the target material can be provided on the surface of thecoil95, in which case the target material is closer to the ultraviolet light source (i.e., the bulb90), more target material is impinged upon by the ultraviolet light, and, correspondingly, more peroxide radicals and super-oxide ions are produced. Ultraviolet light passing through the spaces between rings of thecoil95 and not striking the target material still produces ozone.
• It should be noted that with a coated coil in place, there is no[0050]non-impingement portion97bthat can be defined, because at least some light rays from all angles will strike portions of thecoil95.
• Although the[0051]coil95 as shown in FIGS. 7A, 7B and7C has is comprised of about 10 turns or rings that would encircle thebulb90, the spacing between the rings can be reduced to produce more peroxide radicals and super-oxide ions. Correspondingly, increased spacing, i.e., fewer rings, would produce fewer peroxide radicals and super-oxide ions.
• As would be appreciated by those of skill in the art, structures similar to the coil configuration, such as a mesh, a screen or a perforated tube may be used, with the construction and sizing being determined according to the desired relative amounts of ozone and peroxide radicals/super-oxide ions, based upon the relative area through which ultraviolet light passes unimpeded (for producing ozone) and the area coated with target material (for producing peroxide radicals and super-oxide ions).[0052]
Materials
• Except as specifically noted, the various components may be made of any suitable material. In a specific implementation, the[0053]housing14,support member42,outer tray48,inner tray50 and tray end54 are all made of a plastic, e.g., polycarbonate or UV stabilized ABS.
• It is to be understood that the present invention includes all such modifications as may come within the scope and spirit of the following claims and equivalents thereof.[0054]

Claims (12)

1-4. (cancelled)

5. An air treatment apparatus, comprising:

a base;

a generally frustoconical housing extending upwardly from the base that terminates in a slanting top surface, the housing having an inner surface that defines an interior and a cross section that decreases in size from a lower end adjacent the base to an upper end adjacent the top surface, the housing also having a side surface with louvered openings including an upper air inlet portion that serves as an air inlet and an adjacent lower air outlet portion that serves as an air outlet, the housing also having additional air outlets defined in the lower end of the housing adjacent the base and in the top surface of the housing;

a negative ion generator positioned within the interior of the housing and coupled to the base, the negative ion generator being a hollow cylinder with dielectric outer side and top surfaces and a conductive inner surface;

a fan positioned within the interior above the negative ion generator, the fan being adjacent the air inlet portion of the side surface of the housing;

a photo-ionizing assembly disposed within the interior and generally above the fan and the negative ion generator, the photo-ionizing assembly including a fluorescent bulb and a tray for supporting the bulb, the tray being slidingly removable through a tray opening defined in the side surface of the housing above the air inlet opening; and

an electrical circuit that provides power to the negative ion generator, the fan and the photo-ionizer, the circuit including a power switch, a power supply and a ballast.

6-21. (cancelled)

22. A method for treating air, the method comprising:

producing negative ions on a substantially non-conductive exterior dielectric surface of a negative ion generator by applying a charge to an enclosed inner conductive surface of the negative ion generator;

passing air to be treated along the exterior dielectric surface so that negative ions encounter the passing air; and

exposing air to be treated to a photo-ionizing light source to photo-ionize at least a portion of the passing air such that ozone is produced to oxidize contaminants in the air.

23. The method ofclaim 22, wherein photo-ionizing includes emitting from the light source ultraviolet light that produces ozone upon impingement with air and allowing a portion of the light produced to impinge upon a predetermined target that produces radicals and ions that bond with and reduce volatile organic compounds in the air.

24. A method for treating air, the method comprising:

producing negative ions on a substantially non-conductive exterior dielectric surface of a negative ion generator by applying a charge to an enclosed inner conductive surface of the negative ion generator;

passing air to be treated along the exterior dielectric surface so that negative ions encounter the passing air; and

exposing air to be treated to a photo-ionizing light source that produces light at a desired wavelength to react with airborne matter.

25. The method ofclaim 24, wherein the act of exposing air to be treated to a photo-ionizing light source includes exposing air to ozone produced by light from the photo-ionizing light source striking oxygen in the air.

26. The method ofclaim 24, further comprising providing a target substance and producing at least one of peroxide radicals and super-oxide ions by causing some of the light produced by the photo-ionizing light source to strike the target substance.

27. The method ofclaim 26, wherein the target substance comprises at least about 10% TiO₂by weight.

28. The method ofclaim 26, wherein the target substance comprises about 10-30% TiO₂, about 0-30% Ag and about 0-30% Cu, by weight.

29. A multi-approach method of treating air with an air treatment apparatus, comprising;

providing a housing that defines an interior area;

providing a photo-ionizing assembly positioned within the housing that emits a predetermined wavelength of ultraviolet light, wherein a first portion of the emitted light produces ozone upon impingement with adjacent air and a second portion of emitted light impinges upon a target that produces radicals and ions that bond with and reduce a portion of volatile organic compounds within the air;

providing a negative ion generator positioned within the housing that produces negative ions by an electrical charge applied to an enclosed conductive inner surface, the negative ion generator having a substantially non-conductive outer surface on which the negative ions are formed and from which the negative ions are transferred to the air; and

providing an air moving device adapted to cause air movement through the housing.

30. A multi-function air treatment apparatus, comprising:

a generally enclosed housing in which an interior and a plurality of through openings are defined, at least one of the through openings being an air inlet through which air enters the housing and at least one of the through openings being an air outlet through which air exits the housing;

a negative ion generator positioned within the housing, the negative ion generator having an enclosed charged surface and an opposite outer surface on which negative ions are generated and from which the negative ions are transferred to the air via a negative electrostatic field; and

a photo-ionizing assembly positioned within the housing, the photo-ionizing assembly having a light source that produces light at a desired wavelength to react with airborne matter,

wherein negative ions generated by the negative ion generator interact with and neutralize positively charged airborne particles and the light from the photo-ionizing assembly causes oxidation of at least some of the airborne matter in adjacent air within the housing, and

wherein the power supply is self-limiting such that in steady-state operation, power supplied to the negative ion generator is decreased as the electronegativity of the field decays toward a neutral value.

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