JP2005345767A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a projector, in which the size of a light-modulation device for image formation can be selected for each color luminous flux. <P>SOLUTION: The projector includes the light-modulation devices for image formation corresponding to the plurality of color luminous fluxes and produces projection light by compositing luminous fluxes (image light) emitted from the corresponding light-modulation devices. For example, in a three-panel type projector using three liquid crystal panels 3R, 3G, and 3B, corresponding to the luminous fluxes in red, green and blue which are three primary colors, a correction lens is disposed in a necessary optical path so that where the size of at least one of the three liquid crystal panels is made different from the sizes of the other liquid crystal panels, in relation to a necessary amount of light of each color luminous flux, the sizes of the luminous fluxes emitted from the corresponding liquid crystal panels are adjusted, before a prism 5 used for combining the color luminous fluxes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projector that uses a semiconductor light emitting element such as an LED (light emitting diode) as a light source and synthesizes and projects image light from a plurality of light modulation devices arranged for each of a plurality of color light beams.

In a projector using a white lamp as a light source and a plurality of liquid crystal panels each corresponding to a plurality of color beams of three primary colors as a light modulation device, the sizes of the liquid crystal panels are all the same to prevent color misalignment. ing.
On the other hand, in recent years, a projector using an LED as a light source has been developed. When an LED is used as a light source, advantages such as widening of the color gamut, instant lighting, and long life are given. Even in such a projector using an LED as a light source, conventionally, it has not been considered to select and determine the size of each liquid crystal panel for each light beam (for example, Patent Document 1).
JP 2004-61779 A

  However, when a semiconductor light emitting element such as an LED is used as the light source of each color light beam, optical design can be performed completely independently for each light beam, and depending on the relationship between the required light amount of each color light beam and the luminance of the light source, By appropriately selecting the light modulation area size (or image formation area size) of the light modulation device, the degree of freedom in optical design increases, thereby contributing to cost reduction.

  The present invention has been made in view of the above problems, and in a projector using a semiconductor light emitting element such as an LED as a light source, the light modulation area size of a light modulation device such as a liquid crystal panel used therefor is required for each color beam. The present invention proposes a configuration that can be selected according to the relationship between the amount of light and the luminance of the light source, and a projector that employs the configuration.

The projector of the present invention is a projector that combines a plurality of color light fluxes into projection light, and forms a picture by modulating a semiconductor light emitting element light source arranged for each color light flux and each color light flux based on image information. A light modulation device having a light modulation region size determined for each color light beam, a light synthesis device for combining the color light beams modulated by the light modulation devices, and the light synthesis device A correction lens that changes a size of a color light beam incident on the light combining device to a predetermined size, and the light modulation device for at least one of the light paths of the light beams. And the size of each color light beam incident on the light combining device is made uniform.
According to this, it is possible to determine the size of the light modulation device such as a liquid crystal panel for each color light beam while considering the luminance of the light source, the optical path efficiency, and the like. Therefore, for each color light beam, a system configuration corresponding to the amount of emitted light beam is possible, and the cost can be reduced.

  In the above case, it is preferable that the semiconductor light emitting element light source is composed of LEDs, and a predetermined number of LEDs are arranged for each light source so that the projection light becomes white light. This is because LEDs have advantages such as a wide color gamut, instant lighting, and long life.

  In the projector according to the aspect of the invention, in the case where the plurality of color light beams are three types of red, green, and blue, at least one light modulation device among light modulation region sizes of the light modulation devices corresponding to the color light beams. For reducing the size of the light beam or for increasing the size of the light beam for aligning the size of each color light beam incident on the light combining device in the corresponding optical path. A correction lens is arranged.

For example, in the case where the plurality of color light beams are three types of red, green, and blue, the light modulation area size of the light modulation device corresponding to the green light beam is set to the light modulation device corresponding to the red light beam and the blue light beam. It is preferable that the correction lens for enlarging the size of the luminous flux is disposed in the optical path corresponding to the red luminous flux and the blue luminous flux. According to this, since two of the three light modulation devices can be reduced, the cost of the light modulation device can be reduced, and the utilization rate of the green light that determines the overall brightness is not reduced. .
Further, in the case where the plurality of color light beams are three types of red, green, and blue, the light modulation region size of the light modulation device corresponding to the green light beam is set to the light modulation device corresponding to the red light beam and the blue light beam. It is preferable that the correction lens for reducing the size of the light beam is disposed in the optical path corresponding to the green light beam. According to this, the utilization rate of green light is slightly reduced, but the size of the photosynthesis device and the projection lens can be reduced to reduce their cost.

  The correction lens may be either a single aspherical lens or a lens group composed of a plurality of lenses. In the case of one aspheric lens, the installation space is small, and in the case of a lens group, the resolution can be improved as compared with the case of one aspheric lens.

  Furthermore, the adjustment of the light flux amount of each color light flux may be performed by adjusting the power consumption amount of the semiconductor light emitting element. Further, when the light modulation device is a liquid crystal panel, the light amount of each color light beam may be adjusted by adjusting the opening degree of each liquid crystal panel. By these adjustments, fine adjustment to make the combined light of each color light a predetermined white light becomes possible.

  The present invention is applied to a projector including a light modulation device for image formation corresponding to each of a plurality of color light beams, and combining the light beams (image light) emitted from the light modulation devices into projection light. For example, in a three-plate projector using three liquid crystal panels corresponding to light beams of three primary colors red, green, and blue, at least one of the three liquid crystal panels is related to the required light quantity of each color light beam. When the light modulation area size (or image formation area size) of two panels is different, the size of the light beam emitted from each liquid crystal panel is corrected to the required light path so that it is aligned in front of the device that synthesizes each color light beam. A projector is constructed by incorporating a lens.

  FIG. 1 is a schematic configuration diagram showing an optical system of a projector according to Embodiment 1 of the present invention. This projector includes LED light sources 1R, 1G, and 1B as semiconductor light-emitting element light sources that generate light having wavelengths corresponding to the three primary colors red, green, and blue (hereinafter referred to as red light flux, green light flux, and blue light flux). . The LED light sources 1R, 1G, and 1B are obtained by attaching a plurality of LED chips 1r, 1g, and 1b in a two-dimensional array on a substrate. In addition, this projector includes liquid crystal panels 3R, 3G, and 3B as light modulation devices. Here, the sizes of the light modulation areas of these liquid crystal panels 3R, 3G, and 3B are set to be the same for the liquid crystal panels 3R and 3B, and the liquid crystal panel 3G is set to be larger than the liquid crystal panels 3R and 3B.

The red light beam emitted from the LED light source 1R is condensed by the condenser lens 2R and enters the liquid crystal panel 3R which is a light modulation device. The red light beam modulated in accordance with the predetermined image information in the liquid crystal panel 3R passes through the correction lens 4R and is enlarged and corrected to a light beam having the same size as the light modulation area size of the liquid crystal panel 3G. Then, the red light beam subjected to the magnification correction is incident on a cross dichroic prism 5 (hereinafter simply referred to as a prism 5) as a light combining device.
Similarly, the blue light beam emitted from the LED light source 1B is condensed by the condenser lens 2B and enters the liquid crystal panel 3B which is a light modulation device. The blue light beam modulated according to the predetermined image information in the liquid crystal panel 3G passes through the correction lens 4B and is enlarged and corrected to a light beam having the same size as the light modulation area size of the liquid crystal panel 3G. The enlarged blue light beam is incident on the prism 5.
On the other hand, the green light beam emitted from the LED light source 1G is condensed by the condenser lens 2G and enters the liquid crystal panel 3G which is a light modulation device. The blue light beam modulated according to the predetermined image information in the liquid crystal panel 3G is incident on the prism 5 as it is.
As described above, the light beams (image light) having the same size are incident on the prism 5, synthesized there, and then projected from the projection lens 6. In this example, the dotted line portions indicated by 6R, 6G, and 6B in the figure are the focus surfaces of the projection lens 6.

  In the case of FIG. 1, since the liquid crystal panel corresponding to the other two color light beams is made smaller while giving priority to the amount of green light beam that determines the overall brightness of the projector, the cost of the liquid crystal panel can be reduced. . In addition, since there is no correction lens in the optical path of the green light beam, green light can be used efficiently. In FIG. 1, the light modulation area sizes of the liquid crystal panel 3R and the liquid crystal panel 3B may be different from each other, and correction lenses having different light beam expansion rates may be provided in the optical paths.

  FIG. 2 is a schematic configuration diagram showing an optical system of the projector according to the second embodiment of the invention. The projector includes LEDs 11R, 11G, and 11B as semiconductor light emitting element light sources that generate a red light beam, a green light beam, and a blue light beam. Here, the LED light sources 11R, 11G, and 11B are obtained by attaching a plurality of LED chips 11r, 11g, and 11b in a two-dimensional array on a substrate. In addition, this projector includes liquid crystal panels 13R, 13G, and 13B as light modulation devices. Here, the sizes of the light modulation areas of these liquid crystal panels 13R, 13G, and 13B are the same for the liquid crystal panels 13R and 13B, and the liquid crystal panel 13G is set larger than the liquid crystal panels 13R and 13B.

The red light beam emitted from the LED light source 11R is condensed by the condenser lens 12R and enters the liquid crystal panel 13R which is a light modulation device. The red light beam modulated in accordance with the predetermined image information in the liquid crystal panel 13R is incident on a cross dichroic prism 15 (hereinafter simply referred to as a prism 15) as a light combiner.
Similarly, the blue light beam emitted from the LED light source 11B is condensed by the condenser lens 12B and enters the liquid crystal panel 13B which is a light modulation device. The blue light beam modulated according to the predetermined image information in the liquid crystal panel 13B is incident on the prism 15 as it is.
On the other hand, the green light beam emitted from the LED light source 11G is condensed by the condenser lens 12G and enters the liquid crystal panel 13G which is a light modulation device. The blue light beam modulated in accordance with the predetermined image information in the liquid crystal panel 13G passes through the correction lens 14B and is reduced and corrected to a light beam having the same size as the light modulation area size of the liquid crystal panels 13R and 13B. Then, this reduced and corrected green light beam enters the prism 15.
As described above, the light beams (image light) having the same size are incident on the prism 15, synthesized there, and projected from the projection lens 16. In this example, dotted lines indicated by 16R, 16G, and 16B in the figure are the focus plane of the projection lens 16.

  In the case of FIG. 2, the utilization efficiency of green light that determines the overall brightness is slightly reduced, but the size of the prism 15 and the projection lens 16 can be reduced, so that the cost can be reduced. In FIG. 2, the light modulation areas of the liquid crystal panel 13R and the liquid crystal panel 13B are made different in size, and a correction lens having a different light beam expansion rate is provided in another optical path with reference to one of these panels. Also good. The correction lenses 4R, 4B, and 14G shown in FIGS. 1 and 2 may be a single aspheric lens, or may be formed of a lens group including a plurality of lenses. Which one should be selected may be selected according to the image quality desired to be finally obtained.

Example 1 (Example corresponding to FIG. 1)
Here, a liquid crystal panel having a light modulation area size of 0.7 in XGA (same as the screen size) is adopted as the liquid crystal panels 3R and 3B, and a liquid crystal panel having a light modulation area size of 1.4 in XGA is adopted as the liquid crystal panel 3G. The light transmittance is 22% for the liquid crystal panels 3R and 3B and 27.5% for the liquid crystal panel 3G. The LEDs constituting the LED light sources 1R, 1G, and 1B employ a 0.5 mm square chip 1W LED chip 1r for a red light flux and a 1 mm square chip 2W LED chips 1g and 1b for a green light flux and a blue light flux. To do. Further, the lens efficiency of the correction lenses 4R and 4B for aligning the size of the light beam emitted from the liquid crystal panels 3R and 3B and incident on the prism 5 with the size of the light beam incident on the prism 5 from the liquid crystal panel 3G is 90%, Assume that the optical path efficiency between the LED light sources 1R, 1G, and 1B to the liquid crystal panels 3R, 3G, and 3B is 40%. Further, here, it is assumed that white light of 9000K is obtained as projection light, and for this reason, the LED light source of the three primary colors has a luminous flux ratio of red light: green light: blue light = 21: 76: 4. The luminance per LED chip used here is 44 lm (red LED), 80 lm (green LED), and 20 lm (blue LED).

In the projector, the best output efficiency is obtained when the etendue of the light source and the etendue of the liquid crystal panel are the same. The etendue indicates the geometric size and light distribution of the light source, and the etendue E of the planar light source is obtained by the following equation (1).
E = πAsin ² (θ) (1)
However, A is an element area and (theta) is the angle which the light emission surface perpendicular line and the light beam direction make.
In the case of the projector described above, since both the light source and the liquid crystal panel can be treated as a plane, each etendue is required from equation (1) (Takaaki Yagi, “LED light source for projector”,
O plus E from the March 2004 issue).

Based on the above formula (1), the etendue E of the liquid crystal panels 3R, 3G, 3B is calculated to be 21.1 (mm ² steradian), maximum for a 0.7-inch liquid crystal panel with a maximum incident angle of 12 degrees. A 1.4 inch liquid crystal panel with an incident angle of 12 degrees results in 83.7 (mm ² steradians).
When the etendue E of the LED chip is calculated, it becomes 0.8 (mm ² steradian) for a 0.5 mm square chip and 3.1 (mm ² steradian) for a 1 mm square chip.
Based on these, the number of LED chips (ideal number) required to make the etendue of the light source equal to the etendue of the liquid crystal panel is 27 for the LED light sources 1R and 1G and 7 for the LED light source 1B.

On the other hand, the amount of light beam Gp of the incident surface of the prism 5 for the green light beam that requires the maximum light amount among the three primary colors can be calculated by the following equation (2).
Gp = Ideal number of LEDs × Luminance per LED chip × The above optical path efficiency
× Transmittance of liquid crystal panel × Efficiency of correction lens (2)
Accordingly, when the number of LED chips is ideal 27, the green light flux Gp is 237.6 lm by substituting the previously determined value into the equation (2). Further, with the green light flux Gp as a reference, the necessary light flux of the red light flux Rp and the blue light flux Bp on the incident surface of the prism 5 is obtained from the ratio of the green light flux Gp and the light flux of each color for obtaining white light. . As a result, the red light beam amount Rp = 65.7 lm and the blue light beam amount Bp = 12.5 lm.

  In order to obtain the above light amounts, an ideal number of 27 LED chips 1g is required for the green light flux. On the other hand, 19 LED chips 1r less than the ideal number are required for the red light flux, and 8 LED chips 1b less than the ideal number are required for the blue light flux. The above results are summarized in Table 1.

Example 2 (Example corresponding to FIG. 2)
Here, a liquid crystal panel having a light modulation area size of 0.7 in XGA (same as the screen size) is adopted as the liquid crystal panels 13R and 13B, and a liquid crystal panel having a light modulation area size of 1.4 in XGA is adopted as the liquid crystal panel 13G. The light transmittance is 22% for the liquid crystal panels 13R and 13B and 27.5% for the liquid crystal panel 13G. The LEDs constituting the LED light sources 11R, 11G, and 11B employ a 0.5 mm square chip 1W LED for a red light flux and a 1 mm square chip 2W LED for a green light flux and a blue light flux. Further, the lens efficiency of the correction lens 14G for aligning the size of the light beam emitted from the liquid crystal panel 13G and entering the prism 15 with the size of the light beam incident on the prism 15 from the liquid crystal panels 13R and 13B is set to 80%, and the LED light source 11R. , 11G, 11B to the liquid crystal panels 13R, 13G, 13B is assumed to have an optical path efficiency of 40%. Further, here, it is assumed that white light of 9000K is obtained as projection light, and for this reason, the LED light source of the three primary colors has a luminous flux ratio of red light: green light: blue light = 21: 76: 4. The luminance per LED chip used here is 44 lm (red LED), 80 lm (green LED), and 20 lm (blue LED).

  Based on the above assumptions, the number of LED chips necessary for each color light beam can be calculated by the same method as in the first embodiment. As a result, when the ideal number of 27 LED chips 11g is used for the green luminous flux, 14 LED chips 11r are required for the red luminous flux, and 6 LED chips 11b are necessary for the blue luminous flux. Become. The above results are summarized in Table 2.

  By the way, the number of LED chips actually used shown in Examples 1 and 2 is obtained by rounding up calculation, and considering the product variation of LED chips, in order to obtain predetermined white light, It is preferable that the amount of light emission can be adjusted by adjusting the current consumption of the LED chip of the light source. Instead of adjusting the current consumption of the LED chip and adjusting the light emission amount, the amount of light emitted from each color light beam may be adjusted by adjusting the opening amount of the liquid crystal panel individually for each location. For example, if the dot opening amount of the liquid crystal panel is reduced to 1/3, the same effect as that obtained when the current consumption of the LED chip is reduced to 1/3 can be obtained. Further, regarding the liquid crystal panels 3R, 3B, 13R, and 13B, a 0.5 in XGA panel may be used instead of the 0.7 in XGA panel.

  As mentioned above, although this invention was demonstrated according to embodiment, this invention is not limited to the said embodiment and Example. For example, in the above-described embodiment, an LED is used as the semiconductor light-emitting element that constitutes the light source, but an organic EL light-emitting element, a laser diode, or the like can be used instead. In addition, a fly-eye lens, a rod integrator, or the like can be arranged between the condenser lens for the light emitted from the light source and the light modulation device. In this case, the illumination light is more evenly divided by wavefront division and superposition. And can be incident on the irradiated region of the light modulation device. Further, in the above embodiment, a transmissive liquid crystal panel is used for the light modulation device, but it is configured by a device using a reflective liquid crystal element or a number of micromirrors (equivalent to a digital mirror device manufactured by TI). You can also

It is a schematic block diagram which shows the optical system of the projector which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows the optical system of the projector which concerns on Embodiment 2 of this invention.

Explanation of symbols

1R, 1G, 1B ... LED light source, 1r, 1g, 1b ... LED chip, 2R, 2G, 2B ... condensing lens, 3R, 3G, 3B ... liquid crystal panel, 4B, 4R ... correction lens, 5 ... cross dichroic prism ( Prism), 6 ... projection lens, 6R, 6G, 6B ... focus surface of projection lens, 11R, 11G, 11B ... LED light source, 11r, 11g, 11b ... LED chip, 12R, 12G, 12B ... condensing lens, 13R, 13G, 13B ... liquid crystal panel, 14G ... correction lens, 15 ... cross dichroic prism (prism), 16 ... projection lens, 16R, 16G, 16B ... focus surface of projection lens.

Claims (9)

In a projector that combines multiple color light fluxes into projection light,
A semiconductor light-emitting element light source disposed for each color beam;
A light modulation device that modulates each color beam based on image information to form an image, the light modulation region size of which is determined for each color beam; and
A light synthesizer that synthesizes each color beam modulated by each of the light modulators;
A projection lens that projects the combined light emitted from the light combining device;
A correction lens that changes the size of the color beam incident on the light combining device to a predetermined size is disposed between the light modulating device and the light combining device in at least one of the light paths of the light beams, A projector characterized in that the size of each color beam incident on the light combining device is made uniform.   2. The projector according to claim 1, wherein the semiconductor light-emitting element light source is constituted by LEDs, and a predetermined number of LEDs are arranged for each light source so that the projection light becomes white light. In the case where the plurality of color light fluxes are three types of red, green, and blue,
Of the light modulation area sizes of each light modulation device corresponding to each color beam, the size of at least one light modulation device is made larger or smaller than the size of the other light modulation devices, and the light synthesis is performed in the corresponding optical path. The projector according to claim 1, wherein the correction lens for reducing the size of the light beam or for increasing the size of the light beam for aligning the size of each color light beam incident on the apparatus is disposed. In the case where the plurality of color light fluxes are three types of red, green, and blue,
The light modulation area size of the light modulation device corresponding to the green light flux is larger than the light modulation area size of the light modulation device corresponding to the red light flux and the blue light flux;
3. The projector according to claim 1, wherein the correction lens for enlarging the size of the light beam is disposed in an optical path corresponding to the red light beam and the blue light beam. In the case where the plurality of color light fluxes are three types of red, green, and blue,
The light modulation area size of the light modulation device corresponding to the green light flux is larger than the light modulation area size of the light modulation device corresponding to the red light flux and the blue light flux;
The projector according to claim 1, wherein the correction lens that reduces the size of the light beam is disposed in an optical path corresponding to the green light beam.   6. The projector according to claim 1, wherein the correction lens is one aspheric lens.   The projector according to claim 1, wherein the correction lens includes a plurality of lenses.   The projector according to claim 1, wherein the light amount of each color light beam is adjusted by adjusting a power consumption amount of the semiconductor light emitting element. 8. When the light modulation device is a liquid crystal panel, the light amount of each color light beam is adjusted by adjusting the opening amount for each location of the liquid crystal panel. Projector.

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