JP4821915B2 - Projection type display device and image output device - Google Patents

Description

  The present invention relates to a projection display device and a control method for the projection display device.

As a light modulation device, a liquid crystal display device (LCD), for example, a projection display device (projector) using a mirror device such as a TI (Texas Instruments) DMD (digital micromirror device, registered trademark) element is known, Widely used as a data projector in the office and a video projector at home.
The dynamic range of the projected image in the conventional projection display device is determined by the maximum output and the minimum output of the projection display device, and the dynamic range in one scene or one frame in the video is the maximum pixel value. And the output value from the projection type display device corresponding to the minimum value (for example, see Non-Patent Document 1).

“Nikkei Electronics”, November 24, 2003, p. 114

  For this reason, depending on the image (scene) to be displayed, there is a problem that the dark portion or the bright portion of the image tends to become unclear due to the lack of the dynamic range.

  The present invention has been made to solve the above-described problems, and provides a projection display device that can increase the dynamic range of a projected image and enhance the image quality of the projected image, and a control method thereof. Objective.

In order to achieve the above object, a projection display device according to the present invention includes a first light source that emits light, a first light modulation unit that modulates light from the first light source, and a first light source that emits light. A second light source, a light combining unit that superimposes the light modulated by the first light modulation unit and the light from the second light source, and a projection unit that projects the superimposed light. The light emitted from is modulated in accordance with the image to be projected.

That is, the projection display device of the present invention displays an image by superimposing light from the second light source modulated according to the image on the light representing the image modulated by the first light modulation means. Therefore, compared with the dynamic range of the image displayed only with the light modulated by the first light modulation means, the dynamic range of the image projected by the projection display device can be expanded, The image quality can be improved.
In other words, the upper limit of the dynamic range is expanded by superimposing the light from the second light source modulated according to the image on the image displayed only with the light modulated by the first light modulation means. This enables image display with a wider dynamic range.

In order to realize the above configuration, more specifically, a second light modulation unit that modulates the light emitted from the second light source is arranged between the second light source and the light combining unit. It is desirable.
According to this configuration, since the light emitted from the second light source is modulated by the second light modulation unit, the dynamic range can be expanded in units of fine regions (for example, pixels) of the projected image. Therefore, even if there are areas with significantly different brightness in the same projected image, the dynamic range of the bright area can be expanded, so that the image of the bright area and the dark area can be prevented from becoming unclear. it can.

In order to realize the above configuration, more specifically, the number of pixels formed in the first light modulation unit and the number of pixels formed in the second light modulation unit may be the same.
According to this configuration, since the number of pixels in the first light modulation unit and the second light modulation unit is the same, the dynamic range of the projected image can be flexibly controlled for each pixel of the projection image. .
That is, since the pixels of the first light modulator and the pixels of the second light modulator have a one-to-one correspondence, for each pixel of the projected image, the first light modulator and the first light modulator The pixels of the second light modulation means correspond to each other. As a result, the light modulated by the first light modulation means and the light modulated by the second light modulation means are superimposed on each pixel of the image, so that the dynamic range of the projected image can be flexibly changed for each pixel. Can be controlled.

In order to realize the above configuration, more specifically, the number of pixels formed in the second light modulation unit may be larger than the number of pixels formed in the first light modulation unit.
According to this configuration, the dynamic range of the projected image can be controlled for each pixel corresponding to the pixel formed in the second light modulation unit. For example, light modulated by a plurality of pixels formed on the second light modulation unit is superimposed on an illumination area of light modulated by one pixel formed on the first light modulation unit. The region in which the dynamic range of the projected image can be controlled is defined by the pixels formed in the second light modulation unit.

In order to realize the above configuration, more specifically, the number of pixels formed in the second light modulation unit may be smaller than the number of pixels formed in the first light modulation unit.
According to this configuration, for example, the light is modulated by one pixel formed in the second light modulation unit on the plurality of illumination regions of the light modulated by the plurality of pixels formed in the first light modulation unit. The dynamic range of the projected image can be controlled by superimposing the reflected light.
Therefore, for example, when a mirror device is used as the second light modulation means, a micromirror larger than the pixel of the projected image can be used, and a mirror device that is relatively inexpensive and easy to manufacture can be used.

More specifically, in order to realize the above-described configuration, it is desirable that the second light modulation unit is a mirror device that time-modulates the incident light by controlling the emission direction of the incident light.
According to this configuration, since the second light modulation means is a mirror device, the light can be modulated by controlling the emission direction of the incident light with the mirror. Mirror devices, for example, have higher light modulation efficiency than liquid crystal panels (liquid crystal panels can only modulate predetermined linearly polarized light) and are less susceptible to heat generated from light sources (liquid crystals are vulnerable to high heat). Have Therefore, by using a mirror device, a light source that emits strong light can be used, and the utilization efficiency of light emitted from the light source can be improved.

In order to realize the above configuration, more specifically, expansion of the dynamic range by the second light modulation unit may be determined for each frame of the projection image.
According to this configuration, since the expansion of the dynamic range is determined for each frame, the circuit configuration for determining the expansion of the dynamic range is simplified compared to the case where the expansion of the dynamic range is determined for each frame. can do. In addition, it is possible to simplify the arithmetic algorithm for determining the expansion of the dynamic range.
For example, the circuit configuration can be simplified because it is not necessary to add a storage unit for temporarily storing data for a plurality of frames to the circuit configuration. Further, the calculation algorithm can be simplified because it is not necessary to perform an operation for obtaining gradation consistency over a plurality of frames.

In order to realize the above configuration, more specifically, expansion of the dynamic range by the second light modulation unit may be determined for each of a plurality of frames of the projection image.
According to this configuration, since the expansion of the dynamic range is determined for each of a plurality of frames, the continuity of the luminance of the image between consecutive frames is higher than when the expansion of the dynamic range is determined for each frame. Get better.
In other words, if the expansion of the dynamic range is determined for each frame, the brightness of the same pixel in successive frames may not change continuously (it will suddenly become brighter or darker). By determining the expansion of the dynamic range for each frame, it is possible to reliably prevent the occurrence of the above-described problems.

In order to realize the above configuration, more specifically, the generation of the control signal to the second optical modulation unit may be performed in the apparatus.
According to this configuration, since the control signal is generated in the projection display device, an image with an expanded dynamic range can be projected only by inputting a video signal having only image information. That is, by inputting a normal TV signal, a video signal, or the like to the projection display device, a TV image or a video image with an expanded dynamic range can be easily projected.
Compared with the case where a device for generating a control signal is provided outside the projection type display device, an image with an expanded dynamic range can be projected only by the projection type display device. It has the advantage that it is not necessary.

In order to realize the above configuration, more specifically, the generation of the control signal to the second light modulation unit may be performed in an image output device outside the apparatus.
According to this configuration, since the control signal is generated by inputting the video signal having only the image information to the image output device outside the projection display device, the control signal is generated in the projection display device. Compared with the case where it is performed, the image where the dynamic range was expanded more finely can be projected. In other words, the control signal is generated by an external image output device that has less space restrictions than the projection display device, so that a more complicated and large circuit can be used, thereby enabling fine control by a complicated arithmetic algorithm. It can be carried out.

In order to realize the above configuration, more specifically, a light detection unit that detects ambient ambient light may be provided, and the expansion of the dynamic range may be determined according to the output of the light detection unit.
According to this configuration, since the expansion of the dynamic range is determined according to the brightness of the environment, the dynamic range can be expanded more brightly in a bright environment, and the expansion of the dynamic range can be suppressed in a dark environment. Therefore, the projection display device can project an image that is neither too bright nor too dark with respect to ambient brightness, and can project an image that is easy to see for the viewer.

  A control method for a projection display device according to the present invention includes: a first light source that emits light; a first light modulator that modulates light from the first light source; a second light source that emits light; A control method for a projection display device, comprising: a light combining unit that superimposes light modulated by a first light modulation unit and light from a second light source; and a projection unit that projects the superimposed light. According to the image to be projected, the light from the second light source is superimposed on the light modulated by the first light modulation means, and the dynamic range of the projected image is expanded in the bright direction.

That is, according to the control method of the projection display apparatus of the present invention, the image representing the image modulated by the first light modulation means is displayed by superimposing the light from the second light source modulated according to the image. Therefore, compared with the dynamic range of the image displayed only with the light modulated by the first light modulation means, the dynamic range of the image projected by the projection display device can be expanded, The image quality of the projected image can be improved.
That is, the upper limit of the dynamic range is expanded by superimposing the light from the second light source modulated in accordance with the image on the image displayed only with the light modulated by the first light modulation means ( The image can be displayed in a wider dynamic range.

It is the schematic which shows the projection type display apparatus which concerns on 1st Embodiment by this invention. It is a figure which shows the concept by which illumination light is spatially modulated and time-modulated. It is a figure which shows the concept by which illumination light is spatially modulated and time-modulated. It is a figure which shows the concept by which the dynamic range of a projection image is expanded. It is a figure which shows the concept by which the gradation of a projection image is increased. It is a conceptual diagram with which the dynamic range and gradation of a projection image are increased. It is a block diagram which shows the structure of the drive circuit of a projection type display apparatus. It is a block diagram which shows another structural example of the drive circuit in a projection type display apparatus.

[First Embodiment]
Hereinafter, a projection display device and a control method thereof according to an embodiment of the present invention will be described with reference to FIGS.
First, a projection display device according to an embodiment of the present invention will be described with reference to FIG. The projection display device of the present embodiment includes a transmissive liquid crystal light valve for each of different colors of R (red), G (green), and B (blue), and light that is spatially modulated by the transmissive liquid crystal light valve; This is a projection type color liquid crystal display device that projects white light that has been time-modulated by a mirror device.

FIG. 1 is a diagram showing an outline of a projection display device according to the present embodiment.
As shown in FIG. 1, the projection display device includes a lighting device 1 that emits white light, dichroic mirrors 41 and 42 that split white light into different color lights of R, G, and B, and spatially modulate each color light. Liquid crystal light valves (first light modulation means) 51, 52, 53, a cross dichroic prism 60 that synthesizes each spatially modulated color light, an illumination device 2 that emits white light, and time-modulates white light Mirror device (second light modulation means) 30, cross prism (light synthesis means) 62 that synthesizes spatially modulated and synthesized image light and time modulated light, and a projection lens (projection) that projects the synthesized light (Means) 70.

The illumination device 1 includes a light source (first light source) 10A that emits white light as illumination light, integrator lenses 21 and 22 that uniformize the illuminance distribution of white light, and polarization conversion that aligns the illumination light with one linearly polarized light. And the element 23. The light source 10A includes a lamp 11A such as a high-pressure mercury lamp and a reflector 12 that reflects light from the lamp 11A.
The illumination device 2 includes a light source (second light source) 10B that emits white light and integrator lenses 21 and 22 that uniformize the illuminance distribution of the white light. The light source 10B includes a lamp 11B such as a high-pressure mercury lamp and a reflector 12 that reflects light from the lamp 11B.
The light source 10A and the light source 10B may be composed of a lamp and reflector such as a high-pressure mercury lamp as described above, or may be composed of a solid light source such as a light emitting diode (LED).

  Further, in order to make the illuminance distribution of the light source light uniform in the liquid crystal light valves 51, 52, 53 and the mirror device 30 which are the illuminated areas, the first integrator lens 21 and the second integrator lens from the light sources 10A and 10B side. 22 are sequentially installed. Here, the integrator lenses 21 and 22 are formed as a microlens array in which a plurality of microlenses are arranged in a plane, and the first integrator lens 21 emits light (illumination light) emitted from the light sources 10A and 10B to a plurality of light beams. The second integrator lens 22 has a function as a superimposing lens that superimposes them at the light valve position. In some cases, a condenser lens for superimposing the secondary light source image may be disposed at the position of the second integrator lens 22 or at the subsequent stage. Hereinafter, the case where the second integrator lens is used as the superimposing lens will be described.

The polarization conversion element 23 includes a polarization beam splitter array (PBS array) provided on the light exit side of the second integrator lens 22, and a half-wave plate array that converts the polarization direction of the polarized light reflected by the PBS array. The light polarization direction is aligned in one direction without impairing the light intensity of the light source light.
The dichroic mirrors 41 and 42 are formed by, for example, laminating a dielectric multilayer film on the glass surface, and selectively reflect predetermined color light and transmit light of other wavelengths. That is, the blue / green light reflecting dichroic mirror 41 transmits the red light LR of the white light from the light source 10A and reflects the blue light LB and the green light LG. The green light reflecting dichroic mirror 42 transmits the blue light LB and reflects the green light LG among the blue light LB and the green light LG reflected by the dichroic mirror 41.

The blue / green light reflecting dichroic mirror 41 transmits the red light LR of the white light from the light source 10A and reflects the blue light LB and the green light LG.
The red light LR that has passed through the dichroic mirror 41 is reflected by the reflection mirror 45 and enters the liquid crystal light valve 51 for red light.
On the other hand, of the color light reflected by the dichroic mirror 41, the green light LG is reflected by the dichroic mirror 42 for reflecting green light and enters the liquid crystal light valve 52 for green light. On the other hand, the blue light LB also passes through the dichroic mirror 42 and enters the liquid crystal light valve 53 for blue light through the relay lens 46, the reflection mirror 43, the relay lens 47, the reflection mirror 44, and the relay lens 48.

In the case of this embodiment, the liquid crystal light valves 51, 52, and 53 are formed of an active matrix type transmissive liquid crystal panel in which pixels for displaying an image are arranged in a matrix, and based on a video signal subjected to signal processing. The incident light is driven so as to change the light transmittance (spatial modulation) for each pixel. That is, by controlling the voltage applied to the light transmissive electrode of the liquid crystal light valve, the light transmittance is controlled from a value close to 0% to 100%.
The liquid crystal light valves 51, 52 and 53 use TN (Twisted Nematic) mode active matrix transmissive liquid crystal cells using thin film transistors (hereinafter abbreviated as TFTs) as pixel switching elements. Has been.
The liquid crystal light valves 51, 52, and 53 are arranged so that the modulated color lights LR, LG, and LB are incident on different surfaces of the cross dichroic prism 60.

The cross dichroic prism 60 has a structure in which right angle prisms are bonded together, and a mirror surface that reflects the red light LR and a mirror surface that reflects the blue light LB are formed in a cross shape on the inner surface. Then, the three color lights LR, LG, and LB are combined by these mirror surfaces to form light representing a color image.
A relay lens 61 is disposed on the color image light exit surface of the cross dichroic prism 60, and the color image light is condensed on the cross prism 62.

  The mirror device 30 is arranged so that the micromirrors corresponding to the pixels of the image are arranged in a matrix and the direction of the reflecting surface of the micromirror can be changed (so that it can swing). Further, it is driven to time-modulate the light from the light source 10B based on the video signal subjected to signal processing. The number of micromirrors arranged in the mirror device 30 is the same as the number of pixels formed in the liquid crystal light valves 51, 52 and 53, and the arrangement pattern thereof is also the same.

The cross prism 62 has a structure in which right-angle prisms are bonded together, and a mirror surface that reflects color image light and a mirror surface that reflects light from the light source 10B are formed in a cross shape on the inner surface. Then, the color image light and the light from the light source 10 </ b> B are superimposed by these mirror surfaces and emitted toward the projection lens 70.
The projection lens 70 is arranged so as to enlarge and project the time-modulated light onto the screen 71 on the mirror device 30.

Next, the operation of the projection display device having the above configuration will be described.
A part of the illumination light (white light) emitted from the lamp 11A of the illumination device 1 directly enters the first integrator lens 21 as shown in FIG. The remaining light is reflected by the reflector 12 and enters the first integrator lens 21.
The illumination light incident on the first integrator lens 21 is superimposed by the first integrator lens 21 and the second integrator lens 22 so that the illuminance distribution is uniform in the liquid crystal light valves 51, 52, 53.

Illumination light having a uniform illuminance distribution is separated into linearly polarized light orthogonal to each other by the PBS array of polarization conversion elements 23, and aligned to one linearly polarized light by the half-wave plate array.
The illumination light that has become one linearly polarized light enters the dichroic mirror 41, and the dichroic mirror 41 transmits the red light LR and reflects the blue light LB and the green light LG.
The reflected blue light LB and green light LG enter the dichroic mirror 42, and the dichroic mirror 42 transmits the blue light LB and reflects the green light LG.

  The red light LR is reflected by the reflection mirror 45 and enters the red light liquid crystal light valve 51, and the green light LG enters the green light liquid crystal light valve 52. The blue light LB enters the liquid crystal light valve 53 for blue light through the relay lens 46, the reflection mirror 43, the relay lens 47, the reflection mirror 44, and the relay lens 48.

  Each color light incident on each liquid crystal light valve 51, 52, 53 is spatially modulated for each pixel based on a video signal input to the projection display device and is incident on the cross dichroic prism 60. The spatially modulated color lights are combined in the cross dichroic prism 60 and emitted to the cross prism 62 through the relay lens 61 as light representing a color image.

  On the other hand, the illumination light (white light) emitted from the lamp 11B of the illumination device 2 enters the first integrator lens 21 as shown in FIG. The illumination light incident on the first integrator lens 21 is superimposed by the first integrator lens 21 and the second integrator lens 22 so that the illuminance distribution is uniformized in the mirror device 30.

  Illumination light having a uniform illuminance distribution is incident on the surface of the mirror device 30 on which the micromirrors are arranged. The micromirror has an emission direction of light reflected by each micromirror based on an input video signal, a cross prism 62 direction, and another direction, for example, an absorber (not shown) direction that absorbs light. To control.

  The color image light incident on the cross prism 62 and the light modulated by the mirror device 30 are superimposed and incident on the projection lens 70, and enlarged and projected on the screen 71.

Here, the effect | action which the dynamic range of the image projected by liquid crystal light valve 51,52,53 and the mirror device 30 expands is demonstrated.
FIG. 2A is a diagram illustrating a concept in which illumination light is modulated by a liquid crystal light valve. FIG. 2B is a diagram illustrating a concept in which light modulated by the liquid crystal light valve is modulated by the mirror device and superimposed.
In predetermined pixels in the liquid crystal light valves 51, 52, and 53, as shown in FIG. 2A, spatial modulation is performed so that each color light R, G, and B has a predetermined illuminance based on an input video signal. Has been. Thereafter, as shown in FIG. 2B, the white light of the time-modulated light source 10B is superimposed on each of the spatially modulated color lights R, G, and B by the mirror device 30 based on the video signal, The dynamic range of the pixel is expanded in the bright direction.

FIG. 3A is a diagram illustrating a concept in which illumination light is spatially modulated by a liquid crystal light valve.
FIG. 3B is a diagram illustrating a concept in which light temporally modulated by a mirror device is superimposed on spatially modulated light.
FIGS. 3A and 3B show the light modulation described above with time shown on the horizontal axis. Here, in order to simplify the description, white light having the same RGB value will be described as an example.
In a predetermined pixel in the liquid crystal light valve, as shown in FIG. 3A, temporally continuous light is spatially modulated to have a predetermined illuminance for each frame based on the video signal. Thereafter, as shown in FIG. 3B, the light of the light source 10B, which is time-modulated by the mirror device 30 based on the video signal, is superimposed on the spatially modulated light so that the dynamic range in a predetermined pixel is brighter. It has been expanded.
The modulated light intensity of the mirror device 30 to be superimposed can be controlled for each frame. For example, FIG. 3B shows a case where the modulated light intensity of the mirror device 30 increases with time. Yes.

FIG. 4A is a diagram for explaining the dynamic range of the output value when there is no modulation by the mirror device, and FIG. 4B is a diagram for explaining the dynamic range of the output value when there is modulation by the mirror device. FIG.
4A and 4B, the horizontal axis indicates the pixel value of the video signal, and the vertical axis indicates the output value. The light subjected to spatial modulation by the liquid crystal light valves 51, 52, and 53 is mirrored. The concept of extending the dynamic range of a projected image by superimposing light that has been time-modulated by the device 30 is shown.
For example, in the case of only spatial modulation by the liquid crystal light valves 51, 52, 53, as shown in FIG. 4A, the output value increases from 0 to max as the pixel value increases from 0 to max1. It can be expressed as a dynamic range.
On the other hand, when the modulated light of the liquid crystal light valves 51, 52, and 53 and the modulated light of the mirror device 30 are superimposed, as shown in FIG. It can be expressed as an expanded dynamic range in which the value increases from 0 to max2, which is a value on which light from the light source 10B is superimposed.

FIG. 5 is a diagram for explaining the gradation of the output value when there is modulation by the mirror device.
FIG. 5 shows the pixel value of the video signal on the horizontal axis and the output value on the vertical axis. The light subjected to spatial modulation by the liquid crystal light valves 51, 52 and 53 is time-modulated by the mirror device 30. The concept of increasing the gradation of the projected image by superimposing the reflected light is shown.
For example, when the gradations that can be expressed by the liquid crystal light valves 51, 52, and 53 and the mirror device 30 are 8 gradations, the gradations that can be expressed by the combination of the liquid crystal light valves 51, 52, and 53 and the mirror device 30 are It can be expressed as an intersection of the middle curve and the vertical line (in this case, 64 gradations).
Since the gradations that can be expressed only by the liquid crystal light valves 51, 52, and 53 are the above-described eight gradations, the gradation of the projected image is increased by combining the liquid crystal light valves 51, 52, and 53 and the mirror device 30. be able to.

FIG. 6A is a diagram for explaining the dynamic range and gradation of the output value when there is no modulation by the mirror device, and FIG. 6B is the dynamic range of the output value when there is modulation by the mirror device. It is a figure explaining a gradation.
As described above, the dynamic range of the projected image can be expanded by superimposing the light subjected to the time modulation by the mirror device 30 on the light subjected to the spatial modulation by the liquid crystal light valves 51, 52, 53. , The gradation can be increased. This is illustrated in FIGS. 6A and 6B, in which the horizontal axis represents the pixel value of the video signal and the vertical axis represents the output value.
For example, in the case of only spatial modulation by the liquid crystal light valves 51, 52, and 53, as shown in FIG. 6A, it can be expressed as a dynamic range of output values o1 to o2 with respect to pixel values i1 to i2. Further, the pixel values i1 to i2 can be divided into three levels, and the output values o1 to o2 can be expressed as three levels of gradation.
On the other hand, when the modulated light of the liquid crystal light valves 51, 52, and 53 and the modulated light of the mirror device 30 are superimposed, as shown in FIG. 6A, the output values o′1 to o with respect to the pixel values i1 to i2. It can be expressed as a dynamic range expanded in a bright direction of '2.
Further, the pixel values i1 to i2 are divided into three stages, and each stage is divided into two stages by spatial modulation by the mirror device 30 (divided into six stages as a whole), and the output values o′1 to o '2 can be expressed as 6 levels of gradation.

Next, a driving method of the projection display device of this embodiment will be described.
FIG. 7 is a block diagram showing the configuration of the drive circuit of the projection display device according to this embodiment.
In the present embodiment, as shown in FIG. 7, for example, a video signal that is an analog signal output from a PC, a DVD, or a TV antenna is input to the A / D conversion unit 81, converted into a digital signal, and the control unit 82. Is input.
When the video signal input to the projection display device is a digital signal, the A / D conversion unit 81 that converts the analog signal into a digital signal is not necessary, and the digital signal is directly input to the control unit 82. Also good. In addition, when the video signal input to the projection display device is compressed data such as MPEG2, for example, a decoder unit for decoding the compressed data is provided instead of the A / D conversion unit 81, and the compressed signal is supplied to the decoder unit. Alternatively, the control unit 82 may have a decoding function, and the control unit 82 may input a compressed signal.

Further, the projection display device is provided with an optical sensor (light detection means) 95 that detects the brightness of the surrounding environment. As the optical sensor 95, for example, a CCD (Charge Coupled Device) can be used, and a signal can be output according to the brightness of the environment. A signal output from the optical sensor 95 is input to the control unit 82 via the A / D conversion unit 96.
Note that the A / D conversion unit 96 may or may not be disposed between the optical sensor 95 and the control unit 82 as described above.

In the control unit 82, the control signal value of the light transmittance per frame of the liquid crystal light valves 51, 52, 53 corresponding to each color light from the video signal for a plurality of frames and the output of the optical sensor 95, and the mirror device 30. A control signal value corresponding to the reflectance is determined for each pixel. Video signals for a plurality of frames are temporarily stored in the data storage unit 83 from the control unit 82 and read into the control unit 82 as necessary.
Each signal value described above may be determined from video signals for a plurality of frames, or each signal value described above may be determined from a video signal for one frame. In this case, since the data storage unit 83 that temporarily stores video signals for a plurality of frames is not used, the data storage unit 83 may be omitted.

The light transmittance control signals (digital signals) of the liquid crystal light valves 51, 52, 53 are input to the D / A converters 84, 85, 86 corresponding to the liquid crystal light valves 51, 52, 53, and the analog signal It is converted into a control signal. The control signal (analog signal) is input to the panel drivers 87, 88, 89 corresponding to the liquid crystal light valves 51, 52, 53, and the panel drivers 87, 88, 89 are based on the control signals. , 53 to control the light transmittance in each pixel.
A control signal (digital signal) corresponding to the reflectance of the mirror device 30 is input to the mirror device driver 29, and the mirror device driver 29 controls the reflectance of each mirror of the mirror device 30 based on the control signal.

  According to the above configuration, by superimposing the light from the second light source modulated by the mirror device 30 on the image displayed only with the light modulated by the liquid crystal light valves 51, 52, 53, By expanding the upper limit of the dynamic range of the projected image, it is possible to display an image with a wider dynamic range, and to improve the image quality of the projected image.

  Since the same number of pixels of the liquid crystal light valves 51, 52, 53 and the micro mirrors of the mirror device 30 are formed and correspond one-to-one, the liquid crystal light valves 51, 52 for each pixel of the projected image. , 53 pixels and the mirror device 30 pixels correspond to each other. As a result, the light modulated by the liquid crystal light valves 51, 52 and 53 and the light modulated by the mirror device 30 are superimposed on each pixel of the image, so that the dynamic range of the projected image can be flexibly changed for each pixel. Can be controlled.

  The mirror device 30 has a higher light modulation efficiency than a liquid crystal panel, for example (the liquid crystal panel can only modulate a predetermined linearly polarized light), and hardly deteriorates against heat generated from the light source (the liquid crystal is vulnerable to high heat). Has characteristics. Therefore, by using the mirror device 30, it is possible to use a light source that emits strong light and to improve the utilization efficiency of the light emitted from the light source.

  Since the increase in gradation is determined for each of a plurality of frames, it is possible to consider the continuity of the luminance of the image between consecutive frames, and to reliably prevent the luminance of the pixels from changing discontinuously. it can.

In order to perform the calculation for determining the expansion of the dynamic range by the control unit 82 arranged in the projection type display device, a TV image or video whose dynamic range is expanded by inputting a normal TV signal, a video signal, or the like. An image can be projected.
Compared to the case where a device that calculates the dynamic range expansion is provided outside the projection display device, it can project images with an expanded dynamic range using only the projection display device, so it is highly portable and requires an installation location. It has the excellent point of not.

  Since the expansion of the dynamic range is determined based on the output of the optical sensor 95, the dynamic range can be expanded more brightly in a bright environment, and the expansion of the dynamic range can be suppressed in a dark environment. Therefore, the projection display device can project an image that is neither too bright nor too dark with respect to the surrounding brightness, and can project an image that is easy to see for the viewer.

  The number of pixels formed in the liquid crystal light valves 51, 52, and 53 and the number of micromirrors formed in the mirror device 30 are the same as described above, and may correspond one-to-one. However, the number of pixels formed in the liquid crystal light valves 51, 52, 53 may be larger than the number of micromirrors formed in the mirror device 30, or conversely, formed in the liquid crystal light valves 51, 52, 53. The number of pixels may be smaller than the number of micromirrors formed in the mirror device 30. Furthermore, the number of micromirrors formed in the mirror device 30 may be one.

When the number of pixels formed in the liquid crystal light valves 51, 52, 53 is larger than the number of micromirrors formed in the mirror device 30, for example, a plurality of pixels formed in the liquid crystal light valves 51, 52, 53 The dynamic range of the projected image can be controlled by superimposing the light modulated by one micromirror formed in the mirror device 30 on the plurality of illumination regions of the light modulated by the pixels.
Therefore, when using the mirror device 30, a micromirror larger than the pixel of a projection image can be used, and the mirror device which is comparatively cheap and easy to manufacture can be used.

  When the number of pixels formed in the liquid crystal light valves 51, 52, 53 is smaller than the number of micromirrors formed in the mirror device 30, for example, one of the liquid crystal light valves 51, 52, 53 Since the light modulated by the micromirror of the mirror device 30 is superimposed on the illumination area of the light modulated by the pixels, the region where the dynamic range of the projected image can be controlled is defined by the micromirror of the mirror device 30. Is done. In addition, since the gradation can be simultaneously controlled for each region corresponding to the micromirror of the mirror device 30, a liquid crystal light valve having pixels larger than the pixels of the projected image can be used, and a liquid crystal light that is relatively inexpensive and easy to manufacture. A valve can be used.

  Even if the number of micromirrors formed in the mirror device 30 is one, the light of the light source 10B that is time-modulated over a plurality of frames is superimposed on each color light spatially modulated by the liquid crystal light valves 51, 52, and 53. By doing so, the dynamic range can be expanded.

  As described above, the projection display device may be provided with the optical sensor 95 to control the expansion of the dynamic range in accordance with the ambient brightness. An input unit for instructing the amount of expansion of the dynamic range may be provided, and the dynamic range may be expanded based on a signal from the input unit.

Note that the video signal (analog signal) input to the projection display device may be directly input to the A / D converter 81 as described above, or may be an external PC or a dedicated device as shown in FIG. A control signal for controlling the mirror device 30 is input to the image output device 91 such as a converter, calculated in the image output device 91, a video signal is input to the A / D converter 81, and a control signal is input to the controller 82. You may let them.
According to this configuration, a complicated and large circuit can be arranged in the external image output device 91 that has less space restrictions than the projection display device, as compared with the control unit 82, and accordingly, a detailed floor based on a complicated arithmetic algorithm can be arranged. Key control.

  The light emitted from the light source 10B may be white light as described above, or may not be white light. For example, when the color image synthesized by the liquid crystal light valves 51, 52, and 53 is not balanced, color light that balances the color image may be emitted from the light source 10B.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the light from the light source 10B has been described so as to be adaptive to the configuration in which the light is modulated by the mirror device 30. Instead, the present invention can be applied to a configuration using various other light valves such as a configuration using a liquid crystal light valve.

  In the above embodiment, the light source 10B is always lit and adapted to the configuration of time modulation by the mirror device 30. However, the light source is not limited to the configuration of time modulation by the mirror device 30. The present invention can be applied to various other configurations such as a configuration in which 10B is turned on and off and time-modulated.

  DESCRIPTION OF SYMBOLS 10A ... Light source (1st light source), 10B ... Light source (2nd light source) 30 ... Mirror device (2nd light modulation means), 51, 52, 53 ... Liquid crystal light valve ( First light modulation means) 62 ... Cross prism (light combining means) 70 ... Projection lens (projection means) 91 ... Image output device 95 ... Optical sensor (light detection means)

Claims (7)

A first light source that emits light;
First light modulating means for modulating light from the first light source;
A second light source that is different from the first light source and emits light;
Light combining means for superimposing light modulated by the first light modulating means and light from the second light source;
Projecting means for projecting the superimposed light;
Control means for modulating the time by turning on and off the second light source according to the image projected by the projection means ,
The second light source has a large output value of the light superimposed on a relatively bright image based on the pixel value of the video signal input to the first light modulator, and is relatively dark Modulating the light so that the output value of the light superimposed on the image is small,
The light emitted from the second light source expands the dynamic range of the projected image according to the image projected by the projection unit.   The projection display apparatus according to claim 1, wherein a value of a control signal to the second light source is determined for each frame of an image projected by the projection unit.   The projection display apparatus according to claim 1, wherein a value of a control signal to the second light source is determined for each of a plurality of frames of an image projected by the projection unit.   4. The projection display device according to claim 1, further comprising a control unit that generates a control signal to the second light source. 5. Light detection means for detecting ambient light around the projection display device and outputting a signal corresponding to the detected ambient light;
5. The projection type display device according to claim 1, wherein a value of a control signal to the second light source is determined in accordance with a signal output from the light detection unit. 6. The projection display device according to claim 1, wherein white light is emitted from the second light source. 7. A first light source that emits light, a first light modulator that modulates light from the first light source, a second light source that is different from the first light source and emits light, and the first light source A light synthesizing unit that superimposes the light modulated by one light modulation unit and the light from the second light source, a projection unit that projects the superimposed light, and the second light source is projected by the projection unit. turned on in accordance with the image to be, possess a controlling means for temporal modulation by turning off, and the light emitted from the second light source, projecting a dynamic range of the image to be the projection by the projection means An image output device connected to a projection display device that expands according to an image to be displayed,
Based on the pixel value of the video signal input to the first light modulation means, the output value of the light to be superimposed is large for a relatively bright image and is superimposed for a relatively dark image. Control means for generating a control signal to the second light source that modulates the light so that an output value of the light becomes smaller ;
Output means for outputting the generated control signal to the projection display device;
An image output device comprising:

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