JP2007256830A - Projection display - Google Patents

Abstract

An image quality of a projection display device is improved.
A projection display apparatus includes a light source, an illumination optical system that modulates light from the light source to illumination light, and modulates light from the illumination optical system into an optical image corresponding to a video signal. A display panel 102 and a projection lens 101 for enlarging and projecting light from the display panel 102 are provided. The illumination optical system 104 includes a light modulation element 120 that includes a plurality of movable mirrors 121 that are arranged in a matrix and modulate light incident on the display panel 102 in accordance with a video signal.
[Selection] Figure 1

Description

  The present invention relates to a projection display device, and more particularly to a projection display device using a light valve such as a liquid crystal panel or a semiconductor device equipped with a plurality of mirrors operated by electrical signals.

Projection-type display devices are used for presentations, home theaters, and the like because their screens can be easily enlarged. This type of projection display device mainly includes a light source, an illumination optical system for making light from the light source uniform, and a liquid crystal panel that modulates the light from the illumination optical system into an optical image corresponding to a video signal. The light valve, a projection lens for enlarging and projecting an optical image formed by the light valve, and a screen on which light from the projection lens is projected (see, for example, Patent Document 1).
JP-A-3-111806

In this type of light valve type projection display apparatus, the light valve is irradiated with uniform light from the illumination optical system, and the transmittance and reflectance of the light valve are changed in accordance with the video signal. As a result, an optical image corresponding to the video signal is formed by the light valve, and the video is reproduced on the screen via the projection lens. That is, in this projection display device, an optical image as a luminance distribution is formed by partially narrowing uniform illumination light to reproduce an image.
In such a configuration, for example, when a white pattern with a small area is displayed on a black background and when a white pattern is displayed over the entire surface, the luminance of the white pattern reproduced on the screen is equal. For this reason, the contrast of the image reproduced on the screen tends to be low.
On the other hand, for example, in a CRT display using a cathode ray tube, the luminance when a white pattern with a small area is displayed on a black background can be made brighter than the luminance when a white pattern is displayed over the entire surface. This is because in the case of a cathode ray tube, the beam intensity of the electron beam can be changed according to the luminance information of the video signal.
Due to the difference in characteristics, the CRT display can reproduce a beautiful image having a higher contrast than the projection display device.

However, as compared with CRT displays, projection display devices are relatively easy to increase in size, and as described above, they are used in presentations, home theaters, etc., and demand is increasing, and image quality including contrast is improved. Is expected.
An object of the present invention is to improve image quality in a projection display device.

A projection display device according to a first aspect of the present invention includes a light source, an illumination optical system that modulates light from the light source into illumination light, and a light valve that modulates light from the illumination optical system into an optical image according to a video signal. And a projection optical system for enlarging and projecting light from the light valve. The illumination optical system has a modulation optical system including a plurality of movable mirrors that are arranged in a matrix and modulate light incident on the light valve in accordance with a video signal.
In this projection display device, light from a light source enters a light valve via an illumination optical system and is modulated into an optical image corresponding to a video signal by a light bubble. This optical image is enlarged and projected by a projection optical system to reproduce an image.
Here, light is modulated in accordance with the video signal by the modulation optical system of the illumination optical system and is incident on the light valve. For example, when displaying a white pattern with a small area, a plurality of movable mirrors of the modulation optical system are driven in accordance with the video signal, and light from the light source can be collected in an area corresponding to the white pattern on the light valve. . That is, light that should not contribute to the reproduction of the image in the past can be contributed to the reproduction of the image. As a result, the contrast of the video can be increased as compared with the conventional case, and the image quality can be improved.
A projection display device according to a second invention is the projection display device according to the first invention, wherein the illumination optical system includes at least one lens for collecting light from the light source substantially uniformly on each movable mirror of the modulation optical system. The lens group further includes.

Thereby, the light incident on each movable mirror becomes substantially equal, and the control of the operation of the movable mirror is stabilized according to the image.
A projection display device according to a third aspect of the present invention is the device of the second aspect, wherein the lens group of the illumination optical system includes a lot lens.
According to a fourth aspect of the present invention, there is provided a projection display apparatus according to any one of the first to third aspects of the invention, wherein the F number of the exit side of the illumination optical system in which the F number of the projection optical system is changed by a movable mirror. It is as follows.
This further improves the light utilization efficiency of the entire projection display apparatus.
According to a fifth aspect of the present invention, there is provided a projection display apparatus according to the second or third aspect, wherein the illumination optical system includes at least one lens for condensing light from the modulation optical system onto the light valve. It further has a group.
According to a sixth aspect of the present invention, there is provided a projection display apparatus according to the fifth aspect, wherein the light valve and the modulation optical system are substantially conjugate with each other by the second lens group.
Thereby, the modulation of light by the modulation optical system is easily reflected in the reproduced image.
In a projection display device according to a seventh aspect of the present invention, in any of the first to sixth aspects of the invention, the angle and height of the movable mirror are variable to arbitrary values.

  In the projection display device according to the present invention, since the illumination optical system has a modulation optical system including a plurality of movable mirrors, light that should not contribute to image reproduction in the past is contributed to image reproduction. be able to. Thereby, the contrast of an image can be improved and the image quality can be improved.

Embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
[1] Overall Configuration FIG. 1 shows an example of a schematic configuration diagram of a projection display apparatus 100 as a first embodiment of the present invention. Here, a single-plate type (color filter type) projection display device will be described as an example.
The projection display apparatus 100 mainly modulates a light source 105, an illumination optical system 104 that modulates light from the light source 105 into illumination light, and a light from the illumination optical system 104 into an optical image corresponding to a video signal. A display panel 102 as a light valve, a projection lens 101 as a projection optical system for enlarging and projecting light from the display panel 102, and a screen 106 on which light from the projection lens 101 is projected.
The light source 105 includes a lamp 115 that emits light when a voltage is applied, and a reflector 116 that collects light from the lamp 115. Examples of the lamp 115 include an ultrahigh pressure mercury lamp.
The projection display apparatus 100 is characterized in that illumination light is modulated in the illumination optical system 104 in accordance with a video signal. Specifically, the illumination optical system 104 includes a lens group 111 that captures light from the light source 105, and a light modulation element 120 as a modulation optical system that modulates light emitted from the lens group 111 according to a video signal. Has been. The lens group 111 has a positive power as a whole, and includes, for example, two fly-eye lenses and a lot lens. With the light from the lens group 111, the entire or a part of the light modulation element 120 is illuminated uniformly.

The light modulation element 120 is an element for modulating the light from the lens group 111 and guiding it to the display panel 102, and is disposed on the optical path between the lens group 111 and the display panel 102. The configuration of the light modulation element 120 will be described later.
The display panel 102 is an element for modulating light from the illumination optical system 104 into an optical image corresponding to a video signal, and includes, for example, a transmissive liquid crystal panel. The projection lens 101 enlarges and projects the optical image formed by the display panel 102 onto the screen 106.
[2] Light Modulating Element 120 Here, the light modulating element 120 will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic plan view of the light modulation element 120, and FIG. 3 is an operation explanatory diagram of the movable mirror 121 constituting the light modulation element 120.
As shown in FIG. 2, the light modulation element 120 includes a plurality of movable mirrors 121 arranged in a matrix and a substrate 122 including a mechanism for supporting and driving the movable mirror 121. The movable mirror 121 is composed of a minute rectangular plane mirror, and is provided in the same number as the number of pixels of the display panel 102, for example. In FIG. 2, for the sake of convenience, the number of movable mirrors 121 is set to be smaller than the actually conceivable quantity.

As shown in FIG. 3, each movable mirror 121 can adjust the angle and height with respect to the substrate 122 to arbitrary values within a predetermined range. The movable range of the angle and height of the movable mirror 121 is determined so that the light from the lens group 111 can be reflected to any pixel of the display panel 102.
Since the angle and height of each movable mirror 121 are variable to an arbitrary value, the focal length and illumination range of the illumination optical system 104 change unlike the conventional case. For this reason, the F number on the exit side of the illumination optical system 104 is variable by the movable mirror 121 of the light modulation element 120. In the present embodiment, the F number of the projection lens 101 is set to be equal to or less than the minimum value of the F number on the exit side of the illumination optical system 104.
With the above configuration, the light modulation element 120 can arbitrarily change the shape of the entire reflecting surface, and can arbitrarily adjust the illumination range and illuminance. For example, the light from the lens group 111 can be condensed on an arbitrary region on the display panel 102 by the light modulation element 120.
As for the modulation optical system such as the light modulation element 120, one described in, for example, Japanese Patent No. 3657259 can be considered. Therefore, detailed description of the movable mirror 121 and the substrate 122 is omitted here.

[3] Regarding Each Drive Unit As shown in FIG. 1, the projection display apparatus 100 includes a lamp drive unit 151 that drives the light source 105, a light modulation element drive unit 152 that drives the movable mirror 121 of the light modulation element 120, and the like. The display panel driving unit 153 that drives the display panel 102 and a CPU 154, a ROM 155, and a RAM 156 for controlling and calculating the operation of each driving unit are further provided.
The lamp driving unit 151 is connected to the lamp 115 and applies a voltage to the lamp 115 to cause the lamp 115 to emit light. The light modulation element driving unit 152 is connected to the substrate 122 of the light modulation element 120 and applies a voltage to the support part of the movable mirror 121 to adjust the angle and height of each movable mirror 121 separately. The display panel driving unit 153 applies a voltage to each pixel of the display panel 102 in accordance with video signals sequentially sent from the outside, and modulates light from the illumination optical system 104 into an optical image. The display panel driving unit 153 has a display memory for storing, for example, sequentially sent video signals.
The CPU 154 includes a circuit that controls the operation of each of the driving units 151, 152, and 153, or a circuit that performs an operation based on information acquired from the outside, and the ROM 155, RAM 156, and each driving unit via the bus 158. 151, 152, and 153. For example, a video output device 157 capable of outputting a video signal is connected to the bus 158.

[4] Operation The operation of the projection display apparatus 100 will be described.
As shown in FIG. 1, the light from the light source 105 is converted into uniform light by the lens group 111 of the illumination optical system 104, and the light modulation element 120 is uniformly irradiated. The light incident on the light modulation element 120 is reflected by each movable mirror 121. The light reflected by the movable mirror 121 enters the display panel 102. For example, when the display panel 102 is a transmissive liquid crystal panel, the voltage from the display panel driving unit 153 is applied to the liquid crystal layer according to the video signal, and the light from the light modulation element 120 is distributed as a luminance distribution on the display panel 102. The optical image is modulated. The light transmitted through the display panel 102 is enlarged and projected onto the screen 106 by the projection lens 101, and an image is reproduced on the screen 106.
On the other hand, in the control unit 150, for example, the luminance distribution information for each frame is acquired by the CPU based on the video signal stored in the video storage unit, and the luminance distribution information for each frame is sequentially stored in the RAM. Based on the luminance distribution information, the angle and height of each movable mirror 121 of the light modulation element 120 are adjusted. Specifically, for example, the CPU calculates a total luminance value of one frame from the luminance distribution information, and calculates a luminance ratio for each pixel from the luminance distribution information and the total luminance value. As described above, since the amount of light reflected by one movable mirror 121 is substantially the same, the movable mirror that reflects light to each pixel according to the luminance ratio of each pixel and the position of the pixel on the display panel 102. 121 and its angle and height are determined. For example, in the case of a video in which a white pattern with a small area is projected on a black background, the angle and height of each movable mirror 121 are adjusted so that light is uniformly collected in a region corresponding to the white pattern on the display panel 102. . Further, the horizontal synchronization pulse and the vertical synchronization pulse of the video signal are acquired by the CPU. Based on this synchronization pulse information, the operation of the movable mirror 121 and the operation of the display panel 102 are synchronized. The illumination light modulated by the light modulation element 120 is further modulated into an optical image by the display panel 102 and reproduced on the screen 106 via the projection lens 101.

[4] Effect As described above, in the projection display apparatus 100, the light modulated according to the video signal by the light modulation element 120 of the illumination optical system 104 is incident on the display panel 102. The modulated light is collected in an area where light is necessary on the display panel 102 based on the luminance distribution information of the video signal. That is, light that should not contribute to the reproduction of the image in the past can be contributed to the reproduction of the image. Thereby, in the projection display apparatus 100, the contrast of the image can be increased as compared with the conventional case, and the image quality can be improved.
Further, in the projection display apparatus 100, the limited light from the light source 105 can be positively modulated according to the video signal, so that the light utilization efficiency of the entire apparatus can be improved. For this reason, when it is not necessary to increase the contrast of the image, the low-output lamp 115 can be employed as the light source 105, and the running cost of the projection display apparatus 100 can be reduced. Further, since the F number of the projection lens 101 is less than or equal to the minimum value of the F number on the exit side of the illumination optical system 104 that is changed by the movable mirror 121, the light utilization efficiency of the projection display apparatus 100 as a whole is further improved.
Furthermore, since the light is substantially equally incident on each movable mirror 121 by the lens group 111, the state of the light modulated according to the video signal by the light modulation element 120 is stabilized.

As described above, the projection display apparatus 100 can reproduce a high-quality image with high contrast as compared with the related art.
In this embodiment, the lens group 111 of the illumination optical system 104 is composed of two fly-eye lenses. However, if the lens group 111 has a positive power as a whole, it is composed of a lot lens or other lenses. It may be.
From the viewpoint of improving image quality, it is desirable that the number of movable mirrors 121 be the same as the number of pixels of the display panel 102 or more than the number of pixels of the display panel 102. However, the present invention is not limited to this. Absent.
Further, the projection display device 100 is not limited to a single plate type color filter type, for example, a single plate type color sequential method (with a lot lens and a color wheel) or a three plate type projection display device. Also good. In the case of the single-plate color sequential method, the operation of the movable mirror 121 of the light modulation element 120 is synchronized with the timing of R, G, B color modulation. In the case of the three-plate type, a display panel and a light modulation element are provided for each of R, G, and B components.
Second Embodiment
The projection display device 100 according to the first embodiment described above includes the transmissive display panel 102 as a light valve, but may include a reflective display panel. A projection display apparatus 200 as a second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows an example of a schematic configuration diagram of a projection display apparatus 200 as the second embodiment of the present invention. Note that the description will focus on the configuration different from the first embodiment, and the same reference numerals are used for the same configuration as the first embodiment.

As shown in FIG. 4, the projection display apparatus 200 according to the second embodiment mainly includes a light source 105, an illumination optical system 204 that modulates light from the light source 105 according to an image signal, and an illumination optical system 204. Is composed of a reflective display panel 202 that modulates the light from the light into an optical image corresponding to the video signal, a projection lens 101, and a screen 106.
Examples of the display panel 202 include a reflective liquid crystal panel and a semiconductor device on which a plurality of mirrors that operate in response to an electric signal are mounted. As described above, since the reflective display panel 202 is mounted on the projection display apparatus 200, the configuration of the illumination optical system 204 is different from that of the first embodiment.
Specifically, the illumination optical system 204 is color-modulated with a lot lens 213 for uniformizing light from the light source 105, a color wheel 212 for sequentially color-modulating light from the lot lens 213 in time series. A lens 211 that guides light to the light modulation element 120 and a light modulation element 120 that modulates light from the lens 211 in accordance with a video signal and enters the display panel 202 are configured.
The color wheel 212 is a disk-shaped member in which three color filters of R, G, and B are arranged in the circumferential direction, and is also a member called a color disk. As the color wheel 212 rotates, the color modulation of light from the lot lens 213 is sequentially performed.

In the projection display device 200, the light from the light source 105 is made uniform by the lot lens 213. The uniformed light is sequentially color-modulated by the color wheel 212 and enters the light modulation element 120 through the lens 211. At this time, each movable mirror 121 of the light modulation element 120 is illuminated by the color-modulated uniform light. The movable mirror 121 is driven according to the timing of color modulation and the video signal, and the light incident on the light modulation element 120 is modulated according to the luminance distribution information of the video signal as in the first embodiment. The light modulated by the light modulation element 120 is reflected by the display panel 202, and an optical image corresponding to the video signal is formed. This optical image is enlarged and projected by the projection lens 101, and an image is reproduced on the screen 106.
In the projection display apparatus 200, since the illumination optical system 204 includes the light modulation element 120, it is possible to obtain the same effect as that of the first embodiment described above.
The projection display device 200 is not limited to the color sequential method, and may be a color filter method when the display panel 202 is a reflective liquid crystal panel, for example.
<Third Embodiment>
In addition, as a configuration of the illumination optical system 204 of the projection display apparatus 200 according to the second embodiment, the following cases may be considered. FIG. 5 shows a schematic configuration diagram of a projection display apparatus 300 according to the third embodiment of the present invention. Note that the description will focus on the configuration different from the second embodiment, and the same reference numerals are used for the same configurations as in the first and second embodiments.

As shown in FIG. 5, in the projection display apparatus 300, the illumination optical system 304 further includes a second lens 314 as a second lens group. The second lens 314 is disposed on the optical path between the light modulation element 120 and the display panel 202, and condenses the light modulated by the light modulation element 120 on the display panel 202. Further, the light modulation element 120 and the display panel 202 are in a substantially conjugate relationship by the second lens 314.
In the projection display apparatus 300, in addition to the same effects as those of the second embodiment, the second lens 314 is disposed, so that the light modulation by the light modulation element 120 is easily reflected in the image. That is, the contrast of the video can be further increased, and the image quality of the video can be further improved.
<Other embodiments>
The present invention is not limited to the above-described embodiment, and various changes or modifications can be made without departing from the spirit of the invention.

  Since the projection display apparatus of the present invention has an effect of increasing the contrast of an image, it is useful in a field where a high-quality projection display apparatus is required.

1 is a schematic configuration diagram of a projection display apparatus 100 according to a first embodiment of the present invention. 3 is a schematic plan view of the light modulation element 120. FIG. FIG. 6 is an explanatory diagram of the operation of the movable mirror 121 that constitutes the light modulation element 120. The schematic block diagram of the projection display apparatus 200 which concerns on 2nd Embodiment of this invention. The schematic block diagram of the projection display apparatus 200 which concerns on 3rd Embodiment of this invention.

Explanation of symbols

100, 200, 300 Projection display device 101 Projection lens (projection optical system)
102 Display panel (light valve)
104 Illumination optical system 105 Light source 106 Screen 111 Lens group 120 Light modulation element (modulation optical system)
121 movable mirror 122 substrate 213 lot lens 314 second lens (second lens group)

Claims (7)

A light source;
An illumination optical system that modulates light from the light source into illumination light;
A light valve that modulates light from the illumination optical system into an optical image according to a video signal;
A projection optical system for enlarging and projecting light from the light valve,
The illumination optical system has a modulation optical system including a plurality of movable mirrors arranged in a matrix and modulating light incident on the light valve according to the video signal.
Projection display device. The illumination optical system further includes a lens group including at least one lens that collects light from the light source substantially uniformly with respect to each movable mirror of the modulation optical system.
The projection display device according to claim 1. The lens group of the illumination optical system includes a lot lens,
The projection display device according to claim 2. The F number of the projection optical system is equal to or less than the minimum value of the F number on the exit side of the illumination optical system, which is changed by the movable mirror.
The projection display device according to claim 1. The illumination optical system further includes a second lens group including at least one lens that condenses the light from the modulation optical system on the light valve.
The projection display device according to claim 2. The light valve and the modulation optical system are in a substantially conjugate relationship with the second lens group.
The projection display device according to claim 5. The angle and height of the movable mirror are variable to an arbitrary value.
The projection display device according to claim 1.

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