JP2007072172A - Illumination device and projection-type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device capable of reducing the distribution of illuminance on the light valve of a liquid crystal panel or the like and efficiently illuminating the light valve as a whole, and to provide a projection-type display apparatus. <P>SOLUTION: A light source (LED1) includes a light-emitting element array formed from light-emitting elements arranged in an array. The distribution of the illuminance of light emitted by each light-emitting element (LED1) is removed by a gradient filter 5. Emission light with the distribution of the illuminance reduced is made incident on the first lens array 2 and on the second lens array 3. Thereby the nonuniform brightness of the light source (LED1) is dispersed, and the emission light is made incident on the light modulating means (liquid crystal panel 4). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination device used for a projector device and the like, and a projection display device.

  In recent years, mobile devices such as notebook personal computers have been reduced in size and weight, making them easier to carry around, and presentations using projectors have become widespread. Along with that, projectors are also becoming smaller and lighter.

  However, light source lamps such as halogen lamps and metal halide lamps normally used for projectors are relatively large and heavy. Therefore, a light emitting diode (hereinafter referred to as LED) has been used as a light source lamp that replaces a halogen lamp or a metal halide lamp.

  LED is being actively developed, and the luminous efficiency of the LED element has been improved rapidly, exceeding the luminous efficiency of discharge-type high-pressure mercury lamps and fluorescent lamps, which are said to have the highest luminous efficiency. It has been broken. In addition, LEDs generally have advantages such as long life, high luminous efficiency, high durability, and monochromatic light emission, and are expected to be applied in many lighting fields.

  The following proposals have been made for projectors using LEDs as light sources.

  In Patent Document 1, there is provided a projection type display device including a light source, a light modulation device that modulates light from the light source, and a projection lens that projects light modulated by the light modulation device. A light diffusing means for irradiating the entire light modulation area of the light modulation device with light emitted from each light emitting element. A projection display device has been proposed in which brightness is ensured and a bright image is obtained, and the projection display device is reduced in size, weight, and driving power is reduced.

  In Patent Document 2, a plurality of light emitters composed of a plurality of semiconductor light emitting elements having different emission colors, and a drive for emitting a plurality of output lights in time series by sequentially emitting the plurality of semiconductor light emitting elements for each of the emission colors. Means, a shaping optical system for shaping the plurality of output lights emitted from the plurality of light emitters into parallel light, and a space corresponding to the parallel light from the shaping optical system according to an image signal corresponding to the emission color By having a single spatial light modulator that modulates and outputs a plurality of image signal lights in time series, and a projection optical system that projects the plurality of image signal lights from the spatial light modulator on a screen A projector device has been proposed that has high light utilization efficiency, small size, low power consumption, and long light source life.

In Patent Document 3, a light source composed of a plurality of light-emitting diodes, a liquid crystal light valve that is illuminated by light source light from the light source and modulates the deflection state of the incident illumination light, and light emitted from the liquid crystal light valve is projected. In the image projection apparatus provided with a projection lens for providing a deflection conversion element array that individually deflects and converts the light emitted from each of the light emitting diodes, both high light utilization efficiency and a compact optical system are achieved. An image projection apparatus has been proposed.
JP 2001-249400 A JP-A-11-32278 Japanese Patent Application Laid-Open No. 2002-244211

  However, the above invention has the following problems.

  In the projection display device described in Patent Document 1, the light emitted from the light emitting element is directly incident on the fly-eye lens. Further, in the projector device described in Patent Document 2, the light emitted from the light emitting element is shaped by the microlens array, but after shaping, the light beam width is narrowed and the light is guided to the two-dimensional micro deflection mirror array as it is. Yes.

  In general, emitted light from an LED has different intensities for each outgoing angle, and this intensity distribution is called a light distribution. When the configurations of Patent Documents 1 and 2 are used, it is obvious that the light distribution characteristics of the LEDs appear as illuminance unevenness on the liquid crystal panel or the two-dimensional micro deflection mirror array.

  Even if the projection type display device described in Patent Document 1 uses a bullet-type LED as a light source and increases the directivity of the emitted light and lowers the divergence of the light, the effect of the light distribution characteristics is reduced. The NA of the lens becomes too small to illuminate the entire liquid crystal panel.

  Moreover, although the image projection apparatus described in Patent Document 3 aims for light use efficiency and miniaturization, illumination unevenness has not been studied.

  In other words, although the light emission efficiency of the LED is improved, at present, in order to use the LED as a light source for the projector, if a plurality of LEDs are not arranged, a screen having a size of about A3 paper is assumed. Insufficient brightness. Further, regarding the use of a plurality of LEDs, various methods for efficiently using the light emitted from each LED are conceivable. For example, a method of making a secondary light source by diverting a fly-eye lens of the prior art and coupling each lens in the fly-eye lens and each LED is very efficient. However, the fly-eye lens originally reduces the illuminance unevenness on the light valve surface due to the light distribution characteristic of the light source by dividing the light source light into a plurality of parts. Therefore, the method of coupling the LED and the fly-eye lens has no problem as a method of guiding the light source light to the light valve surface, but does not perform the original function of the fly-eye lens. For this reason, when the LED and the fly-eye lens are simply coupled, the light distribution characteristic of the LED becomes uneven illuminance and appears on the light valve as it is.

  Here, a specific configuration of a conventional projection display apparatus will be described with reference to FIG. The conventional projection display device is composed of LEDs 1 in 3 rows and 3 columns, a first lens array 2 and a second lens array 3, thereby illuminating the liquid crystal plate 4. As shown in FIG. 5, the first lens array 2 and the second lens array 3 receive light emitted from the LEDs 1 and form secondary light source images of the respective LEDs 1. In general, when such a method is used, each secondary light source image illuminates the entire liquid crystal plate, so that illumination with less unevenness is performed efficiently. However, if the LED 1 is not a bullet-type LED in which a lens is attached, the emitted light from the LED 1 has the highest radiation intensity in the front direction of the LED as shown in FIG. (Here, it becomes weaker according to the cosine square of the angle made.) Therefore, since each LED 1 illuminates the entire liquid crystal surface, the light distribution distribution (here, cosine square distribution) of the LED 1 is directly superimposed on the liquid crystal surface and appears as illuminance unevenness as it is.

  Therefore, the present invention comprises a light emitting element array in which light sources are arranged in an array, the illuminance distribution of light emitted from each light emitting element is removed by a gradient filter, and outgoing light having no illuminance distribution is emitted as light. An object of the present invention is to propose an irradiating device and a projection display device capable of reducing the illuminance distribution on a light valve such as a liquid crystal panel and efficiently illuminating the entire light valve by entering the modulation means.

  The invention according to claim 1 is an illumination device including a light source composed of a plurality of light emitting diodes and a light modulation unit that modulates light from the light source. A light diffusing unit that irradiates the entire light modulation region; and a gradient filter having a transmittance distribution that cancels the illuminance distribution of each light source between the light source and the light diffusing unit or inside the light diffusing unit. It is characterized by.

  According to a second aspect of the present invention, in the illumination device according to the first aspect, the light diffusing means includes a pair of fly-eye lenses in which a plurality of lenses are arranged in an array.

  According to a third aspect of the present invention, in the illumination device according to the second aspect, the gradient filter has a one-to-one correspondence with each lens of the fly-eye lens.

  According to a fourth aspect of the present invention, in the illumination device according to the third aspect, the gradient filter is formed as a thin film on each lens surface of one of the fly-eye lenses of the light diffusing means. And

  According to a fifth aspect of the present invention, in the illumination device according to the third or fourth aspect, the gradient filter is made of glass or a plastic material, and the transmittance of the gradient filter is adjusted by changing the thickness of the material. .

  According to a sixth aspect of the present invention, in the illumination device according to the fifth aspect of the present invention, a compensation plate is joined to the gradient filter in order to prevent light from being refracted by a thickness change.

  According to a seventh aspect of the present invention, in the illuminating device according to any one of the first to sixth aspects, an extraction lens system for taking out the emitted light of the light source is disposed between the light source and the light diffusing means. It is characterized by being.

  The invention according to claim 8 is the illumination device according to any one of claims 1 to 7, wherein at least one relay lens is provided between the light diffusion means and the light modulation means. To do.

  A ninth aspect of the invention is a projection display device having the illumination device according to any one of the first to eighth aspects, wherein each of the light sources emits light of a plurality of colors by a single light source. The modulation means includes projection means for time-division driving in synchronism with the emission timing of each color light emitted sequentially from the light source and projecting the light modulated by the light modulation means.

  A tenth aspect of the present invention is a projection display device having the illumination device according to any one of the first to eighth aspects, wherein each of the light sources emits a single color light and emits a single color light source. The light modulated by three or more types of light sources having different color lights, and the light modulation means is time-division driven in synchronization with the emission timing of each color light emitted from the light source in time sequence, and is modulated by the light modulation means. It has the projection means which projects.

  Invention of Claim 11 is a projection type display apparatus provided with the illuminating device of any one of Claim 1-8, Comprising: Each said light source is a several surface which can radiate | emit color light of a mutually different color A light source, and the light modulation means modulates each color light emitted from the surface light source, and combines the color light modulated by the light modulation means, and the light synthesized by the color synthesis means. And projecting means for projecting.

  Invention of Claim 12 is a projection type display apparatus provided with the illuminating device of any one of Claim 1-8, Comprising: The said light source is white LED, The said light modulation means is from said LED. It comprises a color filter that converts the emitted white light into a plurality of colors, and has projection means for projecting the light modulated by the light modulation means.

  The present invention comprises a light emitting element array in which light sources are arranged in an array, and the light intensity emitted from the individual light emitting elements is removed by a gradient filter, and the emitted light having no illuminance distribution is modulated by light. By making it incident on the light bulb, it is possible to reduce the illuminance distribution on the light valve such as a liquid crystal panel and to efficiently illuminate the entire light valve.

  Hereinafter, the configuration and operation of a projection display device according to an embodiment of the present invention will be described.

  The projection type display device according to the present embodiment (shown in FIG. 1) is configured to have 3 rows and 3 columns of LEDs 1, a first lens array 2, a second lens array 3, and a liquid crystal plate 4. Further, a gradient (ND) filter 5 having a transmittance distribution that cancels the orientation distribution characteristics of the LED 1 is provided on each lens of the first lens array 2. In other words, for example, when the orientation distribution of the LEDs 1 is a Lambard distribution, the gradient filter 5 having a characteristic in which the transmittance increases from the center toward the periphery between each LED 1 and the first lens array 2. Before the incident on each lens of the first lens array 2, the cause of the above-mentioned illuminance unevenness is removed.

  Further, in order to efficiently extract the light emitted from the LED 1, it is desirable that the numerical aperture (NA) of the lens coupled with the LED 1 is large. Since the conventional fly-eye lens is usually designed to receive parallel light rays, it is difficult to efficiently extract the light emitted from the LED 1. Further, there is a limit to the method of changing the design of the fly-eye lens and increasing the extraction efficiency of the emitted light from the LED 1. For this reason, it is desirable to arrange a lens system (hereinafter referred to as a coupling lens system) for extracting the emitted light of at least one LED 1 between the LED 1 and the first lens array 2 to improve the NA.

  The projection type display apparatus according to the present embodiment uses the gradient filter 5 having the transmittance distribution as shown in FIG. 2 to cancel the illuminance unevenness of the emitted light emitted from the LED 1. In the projection type display device shown in FIG. 1, by forming this filter film on the first surface (the surface on the LED 1 side) of the first lens array 2, as shown in FIG. We are shining.

  In addition, the method of performing color display with the above-described projection display device can be broadly divided into a method of performing color display by crafting a light valve, and a method of mixing a plurality of color lights with an illumination optical system including a light source. There is a method of performing color display.

  The light valve can be crafted by, for example, a method using a color filter, or a method in which three sub-pixels of red / green / blue are associated with one microlens (TVJ Technical Report VOL.19, NO. 8, IDY95-41). However, the method of adding work to the light valve sacrifices brightness and resolution.

  As a method of mixing a plurality of color lights with an illumination optical system including a light source, a method using an LED including a red / green / blue chip in one element, or a red / green / blue color is emitted. LEDs are arranged and mixed on the light valve, or arranged for each LED of red / green / blue, to produce a red surface light source, a green surface light source, and a blue surface light source. There is a method of mixing colors with a prism or the like.

  In the projection display device according to the present embodiment, a light valve that is time-division driven in synchronization with the emission timing of each color light emitted sequentially from the LED is used.

  Next, the configuration and operation of the projection display apparatus according to the second embodiment will be described.

  The projection type display device according to the present embodiment (shown in FIG. 3) includes 5 rows and 5 columns of LEDs 1, a coupling lens 6 corresponding to each LED 1, a first lens array (with a gradient filter film 5) 2, a second The lens array 3, the relay lens 7, the field lens 8, and the liquid crystal plate 9 are included.

  As described in the first embodiment, it is difficult to efficiently extract the emitted light emitted from the LED 1 using only the fly-eye lens. Therefore, in the present embodiment, the NA is improved by arranging the coupling lens 6 for extracting the light emitted from the LED 1 between the LED 1 and the first lens array 2.

  In addition, the relay lens 7 integrated with the second lens array 3 in the first embodiment is divided, and the field lens 8 is disposed in the vicinity of the liquid crystal plate 4, whereby the relay lens 7 and the field lens 8 are arranged. The aberration of the lens system consisting of When this aberration is large, when the secondary light source image is guided to the liquid crystal plate 4, the light use efficiency is lowered, and further illuminance unevenness is caused.

  The gradient filter 5 may be an absorption type gradient filter shown in FIG. 4 instead of the filter film. A desired transmittance distribution can be obtained by changing the thickness as in the convex lens shown by hatching in FIG. However, in order to prevent refraction in the filter, it is desirable to use a compensation plate such as a concave lens shown in FIG. The refractive index of the compensation plate is the same as that of the convex lens, and the curvature of the concave lens and the curvature of the convex lens are the same.

  By combining the projection optical system with the illumination optical system described above, it is possible to configure a projection display apparatus that is small in size, saves energy, and has little illuminance unevenness.

It is a figure which shows the structure of the projection type display apparatus concerning this embodiment. It is a figure which shows the transmittance | permeability distribution of the gradient filter used for the projection type display apparatus concerning this embodiment. It is a figure which shows the structure of the projection type display apparatus concerning this embodiment. It is the schematic of an absorption type gradient filter. It is a figure which shows the structure of the conventional projection type display apparatus.

Explanation of symbols

1 LED
2 First lens array 3 Second lens array 4 Liquid crystal plate 5 Gradient filter 6 Coupling lens 7 Relay lens 8 Field lens

Claims (12)

In an illumination device having a light source composed of a plurality of light emitting diodes, and a light modulation means for modulating light from the light source,
A light diffusing means for irradiating the entire light modulation area of the light modulation means with the light emitted from each light source;
An illuminating device comprising a gradient filter having a transmittance distribution that cancels an illuminance distribution of each light source between the light source and the light diffusing unit or inside the light diffusing unit.   The lighting device according to claim 1, wherein the light diffusion means includes a pair of fly-eye lenses in which a plurality of lenses are arranged in an array.   The lighting device according to claim 2, wherein the gradient filter has a one-to-one correspondence with each lens of the fly-eye lens.   4. The illumination device according to claim 3, wherein the gradient filter is formed in a thin film shape on each lens surface of one of the fly-eye lenses of the light diffusing means. The gradient filter is made of glass or plastic material,
5. The illumination device according to claim 3, wherein the transmittance of the gradient filter is adjusted by a change in material thickness.   6. The illumination device according to claim 5, wherein a compensation plate is joined to the gradient filter in order to prevent a light refraction action due to a thickness change.   The illumination device according to any one of claims 1 to 6, wherein a take-out lens system for taking out light emitted from the light source is disposed between the light source and the light diffusion means.   8. The lighting device according to claim 1, wherein at least one relay lens is provided between the light diffusing unit and the light modulating unit. 9. A projection display device comprising the illumination device according to any one of claims 1 to 8,
Each of the light sources emits light of a plurality of colors with a single light source,
The light modulation means is time-division driven in synchronization with the emission timing of each color light emitted sequentially from the light source,
A projection type display device comprising projection means for projecting light modulated by the light modulation means. A projection display device comprising the illumination device according to any one of claims 1 to 8,
Each of the light sources is composed of three or more types of light sources that emit color light of one color as a single light source, and the emitted color lights are different from each other,
The light modulation means is time-division driven in synchronization with the emission timing of each color light emitted sequentially from the light source,
A projection type display device comprising projection means for projecting light modulated by the light modulation means. A projection display device comprising the illumination device according to any one of claims 1 to 8,
Each of the light sources is composed of a plurality of surface light sources capable of emitting different color lights.
The light modulation means modulates each color light emitted from the surface light source,
Color combining means for combining the color light modulated by the light modulating means;
Projection type display apparatus comprising projection means for projecting light synthesized by said color synthesis means. A projection display device comprising the illumination device according to any one of claims 1 to 8,
The light source is a white LED;
The light modulation means comprises a color filter that converts white light emitted from the LED into a plurality of colors,
A projection type display device comprising projection means for projecting light modulated by the light modulation means.

Images