JP2009085990A - Image display apparatus and controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid both less-contrast of low- and high-luminance when controlling the amount of light emitted from a light source in accordance with an image input signal. <P>SOLUTION: A controller 200A includes: a signal conversion part 210 for converting an image input signal IN into an image output signal OUT in accordance with a standard conversion rate; a light source light amount control part 220 for controlling the amount of light emitted from the light source in accordance with the image input signal IN; a modulation amount control part 230 for controlling the amount of modulation of a liquid crystal panel 30 in accordance with the image output signal OUT; and an adjustment part 240 for adjusting a low-luminance signal conversion rate at which the image input signal corresponding to a luminance lower than a threshold TH is converted to the image output signal OUT in the case that the amount of light emitted from the light source is reduced by the light source light amount control part 220. The adjustment part 240 adjusts the low-luminance signal conversion rate so that the amount of light emitted from the liquid crystal panel is increased in comparison with the case that the image input signal IN is converted at the standard conversion rate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video display device and a control device that use a light source and a light modulation element that modulates light emitted from the light source.

  A video display device such as a projector or a liquid crystal display (LCD) includes a light source and a light modulation element, and displays a video frame based on a video input signal. The light modulation element modulates light emitted from the light source. The luminance of the displayed video frame is determined by the amount of light emitted from the light source and the modulation amount of the light modulation element.

  In such a video display device, even when the amount of light emitted from the light source is constant and the video input signal changes linearly, the luminance of the video frame changes nonlinearly. For this reason, a signal conversion unit that converts a video input signal into a video output signal according to a predetermined conversion rate is used so that the luminance of the video frame changes linearly with respect to the video input signal.

Further, a light amount control technique for controlling the amount of light emitted from a light source in accordance with a video input signal is known (see, for example, Patent Document 1). For example, in a projector, an iris mechanism arranged at the output stage of the light source adjusts the amount of light emitted from the light source. In such a light amount control technique, it is common to reduce the amount of light emitted from a light source when displaying a dark video frame.
Japanese Patent Laying-Open No. 2006-285140 (Claim 1, FIG. 5, etc.)

  However, when the amount of light emitted from the light source is reduced, the brightness of the video frame is reduced overall. In this case, there is a problem that the contrast of the low luminance area in the video frame is reduced, that is, “blackout” occurs.

  In order to avoid blackout, it is conceivable to increase the conversion rate for converting the video input signal into the video output signal in the signal conversion unit. However, when the conversion rate is increased, there is a problem in that the contrast of the high luminance region in the video frame is reduced, that is, “whitening” occurs.

  Therefore, the present invention has been made to solve the above-described problem, and in the case of controlling the amount of light emitted from the light source according to the video input signal, the video capable of avoiding both blackout and whitening. An object is to provide a display device and a control device.

  In one aspect of the present invention, an image display device (image display device 100) including a light source (light source 10) and a light modulation element (liquid crystal panels 30R, 30G, and 30B) that modulates light emitted from the light source is provided. A signal conversion unit (signal conversion unit 210) that converts a video input signal (video input signal IN) into a video output signal (video output signal OUT) according to a predetermined conversion rate (standard conversion rate α), and according to the video input signal A light source light amount control unit (light source light amount control unit 220) that controls the amount of light emitted from the light source, and a modulation amount control unit (modulation amount) that controls the modulation amount of the light modulation element according to the video output signal. Control unit 230), and when the light source light amount control unit decreases the amount of light emitted from the light source, the video input signal corresponding to a luminance smaller than a predetermined luminance threshold (threshold TH) is output to the video output signal. An adjustment unit (adjustment unit 240) that adjusts a low luminance signal conversion rate (low luminance signal conversion rate β) to be converted, and the adjustment unit is compared with the case of converting the video input signal according to the predetermined conversion rate. The low luminance signal conversion rate is adjusted so that the amount of light emitted from the light modulation element increases.

  According to such a feature, when the light source light amount control unit decreases the light amount emitted from the light source, the adjustment unit emits light from the light modulation element as compared with the case where the video input signal is converted according to the predetermined conversion rate. The low luminance signal conversion rate is adjusted so that the amount of light increases.

  Therefore, even when the light source light amount control unit decreases the light amount emitted from the light source, it is possible to avoid blackout. In addition, for video input signals corresponding to a luminance greater than the predetermined luminance threshold, a predetermined conversion rate is applied instead of a low luminance signal conversion rate, so that whitening does not occur.

  In the above feature of the present invention, the adjustment unit adjusts the low luminance signal conversion rate so that the amount of light emitted from the light modulation element increases as the amount of light reduced by the light source light amount control unit increases. It is preferable to do.

  In the above-described feature of the present invention, the video output signal corresponding to the first divided frame based on the video output signal corresponding to one frame configured in a time division manner by at least the first divided frame and the second divided frame. A first video output signal (video output signal OUT1), and a determination unit (luminance) that determines the second video output signal (video output signal OUT2) that is the video output signal corresponding to the second divided frame The determining unit is configured to integrate the luminance of the second divided frame into the luminance of the first divided frame while maintaining the luminance determined by the video output signal corresponding to the one frame. The first video output signal and the second video output signal are determined, and the adjustment unit determines the video according to the predetermined conversion rate. If converting an input signal, so as not to interfere with that all of the luminance of the second divided frame is integrated to the luminance of the first divided frame, it is preferable to adjust the low luminance signal conversion.

  In the above feature of the present invention, the adjustment unit adjusts the low luminance signal conversion rate so that the amount of light emitted from the light modulation element increases as the amount of light reduced by the light source light amount control unit increases. The light source light amount control unit is configured to adjust the low luminance signal conversion rate from the light source when the luminance of the second divided frame is prevented from being integrated into the luminance of the first divided frame. It is preferable to increase the amount of emitted light.

  In the above feature of the present invention, the adjustment unit may prevent the adjustment of the low luminance signal conversion rate from preventing all of the luminance of the second divided frame from being integrated into the luminance of the first divided frame. It is preferable to reduce the predetermined luminance threshold.

  In one aspect of the present invention, a control device (control device 200A, 200B) that controls a light source and a light modulation element that modulates light emitted from the light source converts a video input signal into a video output signal according to a predetermined conversion rate. A signal conversion unit for converting to a light source, a light source light amount control unit for controlling a light amount emitted from the light source according to the video input signal, and a modulation amount of the light modulation element according to the video output signal A low-brightness signal for converting the video input signal corresponding to a luminance smaller than a predetermined luminance threshold to the video output signal when the light source light quantity control unit reduces the amount of light emitted from the light source by a modulation amount control unit An adjustment unit that adjusts the conversion rate, and the adjustment unit increases the amount of light emitted from the light modulation element as compared with the case where the video input signal is converted according to the predetermined conversion rate. Serial adjusting low luminance signal conversion.

  ADVANTAGE OF THE INVENTION According to this invention, when controlling the light quantity radiate | emitted from a light source according to a video input signal, the video display apparatus and control apparatus which can avoid both black-out and white floating can be provided.

  Next, first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings in the first and second embodiments, the same or similar parts are denoted by the same or similar reference numerals. In the following first and second embodiments, a projection-type image display device will be described.

[First Embodiment]
(Configuration of video display device)
FIG. 1 is a schematic configuration diagram of a video display device 100 according to the first embodiment. As shown in FIG. 1, the video display device 100 includes a light source 10, a fly-eye lens unit 20, a plurality of liquid crystal panels 30R, 30G, and 30B, a cross dichroic prism 40, a projection lens unit 50, and an iris mechanism 80. And have.

  The light source 10 emits white light including red component light R, green component light G, and blue component light B. For example, the light source 10 is a UHP lamp that emits white light.

  The fly-eye lens unit 20 is an optical element that makes white light emitted from the light source 10 uniform. Specifically, the fly-eye lens unit 20 is composed of a pair of fly-eye lenses, and each fly-eye lens is composed of a plurality of minute lenses.

  The iris mechanism 80 is disposed between the pair of fly eye lenses. The iris mechanism 80 has a light passage port through which white light emitted from the light source 10 passes. The aperture ratio of the light passage opening is controlled by the control device 200A (see FIG. 2). The smaller the aperture ratio of the light passage opening, the more the amount of white light from the light source 10 decreases.

  The liquid crystal panel 30R is a light modulation element that modulates the red component light R. The liquid crystal panel 30G is a light modulation element that modulates the green component light G. The liquid crystal panel 30B is a light modulation element that modulates the blue component light B.

  The cross dichroic prism 40 combines the color component lights emitted from the liquid crystal panels 30R, 30G, and 30B, and emits the combined light of the color component lights to the projection lens unit 50 side.

  The projection lens unit 50 projects the combined light (that is, video light) emitted from the cross dichroic prism 40 onto a screen (not shown).

  The video display apparatus 100 includes a dichroic mirror 61, a dichroic mirror 62, a reflection mirror 71, a reflection mirror 72, and a reflection mirror 73.

  The dichroic mirror 61 is a color separation element that transmits the blue component light B and reflects the red component light R and the green component light G. The dichroic mirror 62 is a color separation element that transmits the red component light R and reflects the green component light G.

  The reflection mirror 71 reflects the blue component light B and guides the blue component light B to the liquid crystal panel 30B side. The reflection mirror 72 and the reflection mirror 73 reflect the red component light R and guide the red component light R to the liquid crystal panel 30R side.

(Configuration of control device)
Next, the configuration of the control device according to the first embodiment will be described with reference to FIG. A control device 200 </ b> A shown in FIG. 2 is provided in the video display device 100.

  The control device 200A includes a signal conversion unit 210, a light source light amount control unit 220, a modulation amount control unit 230, and an adjustment unit 240.

  The signal conversion unit 210 receives a video input signal IN from a DVD playback device or a TV tuner. The video input signal IN includes a red input signal, a green input signal, and a blue input signal.

  The signal converter 210 converts the video input signal IN into a video output signal OUT. The video output signal OUT includes a red output signal, a green output signal, and a blue output signal.

  The light source light quantity control unit 220 controls the light quantity emitted from the light source 10 according to the video input signal IN. Specifically, the light source light quantity control unit 220 generates a luminance histogram based on the luminance video input signal IN corresponding to one frame. Alternatively, the light source light quantity controller 220 detects the average luminance of the video frame based on the luminance video input signal IN corresponding to one frame.

  In the present embodiment, the light source light quantity control unit 220 detects the maximum luminance value in the video frame based on the luminance histogram, and adjusts the aperture ratio of the iris mechanism 80 according to the detected maximum value. That is, the light source light quantity control unit 220 decreases the aperture ratio of the iris mechanism 80 as the maximum luminance value in the video frame decreases.

  The modulation amount control unit 230 controls the modulation amounts (light transmission amounts) of the liquid crystal panels 30R, 30G, and 30B in accordance with the video output signal OUT generated by the signal conversion unit 210.

  Specifically, the modulation amount control unit 230 controls the modulation amount of the liquid crystal panel 30R according to the red output signal included in the video output signal OUT. The modulation amount control unit 230 controls the modulation amount of the liquid crystal panel 30G according to the green output signal included in the video output signal OUT. The modulation amount control unit 230 controls the modulation amount of the liquid crystal panel 30B according to the blue output signal included in the video output signal OUT.

  The adjustment unit 240 adjusts the conversion rate at which the signal conversion unit 210 converts the video input signal IN to the video output signal OUT. The conversion rate includes two of a standard conversion rate α and a low luminance signal conversion rate β.

  The standard conversion rate α is used when the light amount control unit 220 does not decrease the amount of light emitted from the light source 10, that is, when the aperture ratio in the iris mechanism 80 is 100%.

  The low luminance signal conversion rate β is a conversion rate applied to the video input signal IN corresponding to the luminance smaller than the threshold value TH when the light source light amount control unit 220 decreases the light amount emitted from the light source 10. . However, even when the light source light amount control unit 220 decreases the light amount emitted from the light source 10, the standard conversion rate α is applied to the video input signal IN corresponding to the luminance equal to or higher than the threshold value TH.

  The adjustment unit 240 adjusts the low luminance signal conversion rate β according to the light amount control coefficient by which the light source light amount control unit 220 controls the aperture ratio in the iris mechanism 80.

  Specifically, the adjustment unit 240 increases the low luminance signal conversion rate β as the aperture ratio in the iris mechanism 80 decreases. When the low luminance signal conversion rate β increases, the low luminance signal in the video input signal IN is amplified in the signal conversion unit 210.

  Alternatively, when the low luminance signal conversion rate β increases, the signal conversion unit 210 increases the bit width of the low luminance signal in the video input signal IN.

  As a result, even if the aperture ratio in the iris mechanism 80 is reduced, the contrast of the low luminance region in the video frame displayed by the video display device 100 is improved.

(Operation of control device)
Next, operation example 1 to operation example 3 of the control device 200A will be described with reference to FIG. 3A to 3B, the left diagram shows a luminance histogram generated by the light source light quantity control unit 220. The center diagram shows the conversion rate in the signal converter 210. The right figure shows the γ characteristic of the entire video display device 100.

(1) Operation example 1
FIG. 3A shows a case where the brightness of the brightest part in the brightness video input signal IN corresponding to one frame reaches the maximum brightness.

  As shown in the left diagram of FIG. 3A, the light source light quantity control unit 220 generates a luminance histogram based on the video input signal IN corresponding to one frame. Here, since the luminance reaches the maximum luminance in the video frame, the light source light amount control unit 220 does not decrease the light amount emitted from the light source 10.

  As shown in the central diagram of FIG. 3A, the signal converter 210 converts the video input signal IN into the video output signal OUT according to the standard conversion rate α. In FIG. 3, for convenience of explanation, the standard conversion rate α is assumed to be linear.

  Since the light quantity emitted from the light source 10 is not reduced by the light source quantity control unit 220, the video display device 100 can output up to the maximum luminance (100%) as shown in the right figure of FIG.

(2) Operation example 2
FIG. 3B shows an operation when the luminance of the brightest part in the luminance video input signal IN corresponding to one frame is 0.9 times the maximum luminance.

  As shown in the left diagram of FIG. 3B, since the maximum value in the luminance histogram is 0.9 times the maximum luminance, the light source light amount control unit 220 sets the light amount emitted from the light source 10 to 0.9, which is the maximum light amount. The aperture ratio of the iris mechanism 80 is controlled so as to be doubled.

  As shown in the center diagram of FIG. 3B, the adjustment unit 240 increases the amount of light emitted from the liquid crystal panels 30R, 30G, and 30B as compared with the case of converting the video input signal IN according to the standard conversion rate α. In addition, the low luminance signal conversion rate β is adjusted. That is, the adjustment unit 240 makes the low luminance signal conversion rate β larger than the standard conversion rate α.

  Specifically, the adjustment unit 240 increases the low luminance signal conversion rate β by the reciprocal of the amount of light emitted from the light source 10. Since the amount of light emitted from the light source 10 is 0.9 times the maximum amount of light, the low luminance signal conversion rate β is 1.1 times (1 / 0.9 times) the standard conversion rate α.

  As a result, a low luminance signal conversion rate β that is 1.1 times the standard conversion rate α is applied to the input signal IN smaller than the threshold value TH. For example, the threshold value TH can be an intermediate gradation in the video input signal IN.

  Since the light amount emitted from the light source 10 is 0.9 times the maximum light amount, the video display device 100 can output up to 90% of the maximum luminance as shown in the right diagram of FIG.

(3) Operation example 3
FIG. 3C shows an operation when the brightness of the brightest part in the brightness video input signal IN corresponding to one frame is 0.7 times the maximum brightness.

  As shown in the left diagram of FIG. 3C, since the maximum value in the luminance histogram is 0.7 times the maximum luminance, the light source light amount control unit 220 sets the light amount emitted from the light source 10 to 0.7 of the maximum light amount. The aperture ratio of the iris mechanism 80 is controlled so as to be doubled.

  As shown in the center diagram of FIG. 3C, the adjustment unit 240 increases the low luminance signal conversion rate β by the reciprocal of the amount of light emitted from the light source 10. Since the light amount emitted from the light source 10 is 0.7 times the maximum light amount, the adjustment unit 240 sets the low luminance signal conversion rate β to about 1.4 times (1 / 0.7 times) the standard conversion rate α. To do.

  Since the amount of light emitted from the light source 10 is 0.7 times the maximum amount of light, the video display device 100 can output up to 70% of the maximum luminance as shown in the right figure of FIG.

(Function and effect)
According to the first embodiment, when the light source light amount control unit 220 decreases the light amount emitted from the light source 10, the adjustment unit 240 is used when the signal conversion unit 210 converts the video input signal IN according to the standard conversion rate α. In comparison, the low luminance signal conversion rate β is adjusted so that the amount of light emitted from the liquid crystal panels 30R, 30G, and 30B increases.

  Therefore, even when the video display apparatus 100 displays a dark video frame, it is possible to avoid blackout. Further, since the standard conversion rate α is applied to the video input signal IN corresponding to the luminance greater than the threshold value TH, whitening does not occur.

  Further, according to the first embodiment, the adjustment unit 240 increases the low luminance signal conversion rate β as the light amount that the light source light amount control unit 220 decreases increases.

  Therefore, as the video frame displayed by the video display device 100 becomes darker, the luminance of the low-brightness region in the video frame is increased, so that it is possible to more reliably avoid blackout.

[Second Embodiment]
In the second embodiment of the present invention, differences from the above-described first embodiment will be mainly described.

(Configuration of control device)
FIG. 4 is a block diagram illustrating a configuration of a control device 200B according to the second embodiment. As shown in FIG. 4, the control device 200 </ b> B is different from the control device 200 </ b> A shown in FIG. 2 in that it includes a luminance accumulation unit (decision unit) 250.

  The luminance accumulation unit 250 increases the frame rate of the video output signal OUT and accumulates luminance according to the luminance integration method. In the present embodiment, the luminance accumulation unit 250 determines the first video output signal OUT1 corresponding to the first divided frame based on the video output signal OUT, and the second video output signal OUT2 corresponding to the second divided frame. To decide.

  When the frame rate of the video output signal OUT is increased, the same pixel may emit light a plurality of times in succession, resulting in image blur corresponding to the number of times of light emission. As described above, when the frame rate of the video output signal OUT is doubled, double lines are likely to occur.

  Therefore, the luminance accumulation unit 250 accumulates the luminance of the second divided frame in the first divided frame while maintaining the luminance in one frame period. This reduces the frequency with which the same pixel emits light a plurality of times in succession, making it difficult to generate double lines.

  However, as described in the first embodiment, when the luminance of the low luminance signal is increased, the luminance accumulation unit 250 is prevented from accumulating all the luminance of the second divided frame into the luminance of the first divided frame. . Such a problem may not occur if the low luminance signal is converted according to the predetermined conversion rate α.

  Therefore, in the present embodiment, if the light source light quantity control unit 220 and the adjustment unit 240 convert the video input signal IN according to the predetermined conversion rate α, all of the luminance of the second divided frame is integrated into the luminance of the first divided frame. In order not to prevent this, the low luminance signal conversion rate β is adjusted.

(Operation of control device)
Next, the operations of the luminance accumulation unit 250 and the operations of the light source light quantity control unit 220 and the adjustment unit 240 will be described with reference to FIGS.

(1) Operation of Luminance Accumulation Unit 250 FIG. 5 is an operation explanatory diagram for explaining the operation of the luminance accumulation unit 250.

  The luminance output unit 250 receives a video output signal OUT as shown in FIG. 5A in units of frame periods.

  In FIG. 5A, the luminance of the video frame in the frame period T1 is 100%, the luminance of the video frame in the frame period T2 is 50%, and the luminance of the video frame in the frame period T3 is 20%.

  In FIG. 5A, the luminance accumulation unit 250 divides the frame period T into a divided frame period TA and a divided frame period TB. In each of the divided frame period TA and the divided frame period TB, the luminance in the frame period T is maintained.

  As shown in FIG. 5C, the luminance accumulating unit 250 includes the first video output signal OUT1 and the second video output signal so that the luminance of the second divided frame period TB is accumulated in the first divided frame period TA. OUT2 is determined.

  In the frame period T2, all the luminance in the second divided frame period TB2 is accumulated in the first divided frame period TA2, and the luminance in the first divided frame period TA2 is 100%.

  Further, in the frame period T3, all of the luminance in the second divided frame period TB3 is accumulated in the first divided frame period TA3, and the luminance in the first divided frame period TA3 is 40%.

(2) Operations of the light source light quantity control unit 220 and the adjustment unit 240 Since the luminance is 50% in the frame period T2 shown in FIG. 5, all the luminances in the second divided frame period TB2 are in the first divided frame period TA2. It was collected in. However, when the luminance of the low luminance signal is increased as described in the first embodiment, the luminance in the frame period T2 may exceed 50%.

  Therefore, the light source light amount control unit 220 controls the aperture ratio in the iris mechanism 80 so as to increase the light amount emitted from the light source 10 according to the luminance integration rate. The luminance integration rate is calculated based on the video input signal IN corresponding to one frame, and means the proportion of pixels whose luminance is a certain value (for example, 50%) or less among all the pixels in the video frame.

  That is, the higher the luminance integration rate, the easier it is for the luminance integration unit 250 to integrate all of the luminance in the second divided frame period TB in the first divided frame period TA. On the other hand, as the luminance integration rate is lower, it is more difficult for the luminance integration unit 250 to integrate all of the luminance in the second divided frame period TB in the first divided frame period TA.

  Therefore, as shown in FIG. 6, the light source light amount control unit 220 performs control to increase the light source light amount as the luminance integration rate is lower. Specifically, the light source light quantity control unit 220 multiplies the light quantity control coefficient obtained based on the luminance histogram by the control gain shown in FIG.

  Since the adjustment unit 240 increases the low luminance signal conversion rate β as the light amount that the light source light amount control unit 220 decreases increases, the low luminance signal conversion rate β is controlled by performing control to increase the light source light amount. It can be prevented from increasing.

(Function and effect)
According to the second embodiment, the light source light amount control unit 220 and the adjustment unit 240 prevent the luminance of the second divided frame from being integrated into the luminance of the first divided frame by adjusting the low luminance signal conversion rate β. The amount of light emitted from the light source 10 is increased.

  Since the low luminance signal conversion rate β can be decreased by increasing the amount of light emitted from the light source 10, the luminance accumulation unit 250 accumulates all the luminances of the second divided frame in the first divided frame. It can be prevented.

[Other Embodiments]
As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the second embodiment described above, the light source light amount control unit 220 performs control to increase the light source light amount as the luminance integration rate is lower. However, as illustrated in FIG. 7, the adjustment unit 240 may be configured to decrease the low luminance signal conversion rate β as the luminance integration rate is lower. Even in such a configuration, the same effect as in the second embodiment can be obtained.

  Alternatively, as illustrated in FIG. 8, the adjustment unit 240 may be configured to decrease the threshold value TH as the luminance integration rate is lower. Even in such a configuration, the same effect as in the second embodiment can be obtained.

  In the first and second embodiments described above, a UHP lamp that emits white light is used as the light source 10. However, not only UHP lamps but also solid light sources such as LEDs and LDs can be used.

  In the second embodiment, the luminance accumulation unit 250 doubles the frame rate of the video output signal OUT. However, the frame rate is not limited to 2 and may be 3 or more.

  In the first and second embodiments, the liquid crystal panels 30R, 30G, and 30B are used as the light modulation elements, but not limited to the liquid crystal panels, DMD (registered trademark) or the like may be used.

  In the first and second embodiments, the case where the control devices 200A and 200B are applied to the projection-type image display device 100 has been described. However, the control devices 200A and 200B may be applied to a liquid crystal display (LCD). In this case, the light source light amount control unit 220 controls the emitted light amount of the backlight (light source) of the LCD instead of the iris mechanism 80.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

1 is a schematic configuration diagram of a video display device according to a first embodiment of the present invention. It is a block diagram which shows the structure of the control apparatus which concerns on 1st Embodiment of this invention. It is operation | movement explanatory drawing explaining operation | movement of the control apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the control apparatus which concerns on 2nd Embodiment of this invention. It is operation | movement explanatory drawing explaining operation | movement of the brightness | luminance integration part which concerns on 2nd Embodiment of this invention. It is operation | movement explanatory drawing explaining operation | movement of the light source light quantity control part which concerns on 2nd Embodiment of this invention. It is operation | movement explanatory drawing explaining the other operation example of the control apparatus which concerns on 2nd Embodiment of this invention. It is operation | movement explanatory drawing explaining the other operation example of the control apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Light source, 20 ... Fly eye lens unit, 30R, 30G, 30B ... Liquid crystal panel, 40 ... Cross dichroic prism, 50 ... Projection lens unit, 61, 62 ... Dichroic mirror, 71-73 ... Reflection mirror, 80 ... Iris mechanism , 100 ... Video display device, 200A, 200B ... Control device, 210 ... Signal conversion unit, 220 ... Light source light quantity control unit, 230 ... Modulation amount control unit, 240 ... Adjustment unit, 250 ... Luminance integration unit

Claims (6)

A video display device comprising a light source and a light modulation element that modulates light emitted from the light source,
A signal converter that converts the video input signal into a video output signal according to a predetermined conversion rate;
A light source light quantity control unit for controlling the light quantity emitted from the light source in accordance with the video input signal;
A modulation amount control unit that controls a modulation amount of the light modulation element according to the video output signal;
Adjustment for adjusting a low luminance signal conversion rate for converting the video input signal corresponding to a luminance smaller than a predetermined luminance threshold to the video output signal when the light source light amount control unit decreases the light amount emitted from the light source. With
The adjustment unit adjusts the low luminance signal conversion rate so that the amount of light emitted from the light modulation element is increased as compared with the case where the video input signal is converted according to the predetermined conversion rate. Video display device.   The said adjustment part adjusts the said low-intensity signal conversion rate so that the light quantity radiate | emitted from the said light modulation element may increase, so that the light quantity which the said light source light quantity control part decreases increases. 2. The video display device according to 1. Based on the video output signal corresponding to one frame constituted by time division by at least the first divided frame and the second divided frame, the first video output signal which is the video output signal corresponding to the first divided frame is A determination unit for determining and determining a second video output signal that is the video output signal corresponding to the second divided frame;
The determination unit may maintain the luminance determined by the video output signal corresponding to the one frame, and integrate the luminance of the second divided frame into the luminance of the first divided frame. Determining an output signal and the second video output signal;
If the adjustment unit converts the video input signal according to the predetermined conversion rate, the low-brightness is not disturbed so that all the luminances of the second divided frames are not integrated into the luminances of the first divided frames. The video display device according to claim 1, wherein a signal conversion rate is adjusted. The adjustment unit adjusts the low luminance signal conversion rate so that the amount of light emitted from the light modulation element increases as the amount of light reduced by the light source light amount control unit increases.
The light source light quantity control unit emits light from the light source when the adjustment of the low luminance signal conversion rate prevents all the luminance of the second divided frame from being integrated into the luminance of the first divided frame. The video display device according to claim 3, wherein the amount of light to be increased is increased.   The adjustment unit decreases the predetermined luminance threshold when the adjustment of the low luminance signal conversion rate prevents the luminance of the second divided frame from being integrated into the luminance of the first divided frame. The video display apparatus according to claim 3. A control device that controls a light source and a light modulation element that modulates light emitted from the light source,
A signal converter that converts the video input signal into a video output signal according to a predetermined conversion rate;
A light source light quantity control unit for controlling the light quantity emitted from the light source in accordance with the video input signal;
A modulation amount control unit that controls a modulation amount of the light modulation element according to the video output signal;
Adjustment for adjusting a low luminance signal conversion rate for converting the video input signal corresponding to a luminance smaller than a predetermined luminance threshold to the video output signal when the light source light amount control unit decreases the light amount emitted from the light source. With
The adjustment unit adjusts the low luminance signal conversion rate so that the amount of light emitted from the light modulation element is increased as compared with the case where the video input signal is converted according to the predetermined conversion rate. Control device.

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