JP4609385B2 - Display device and projection display device - Google Patents

Description

  The present invention relates to an image display device, a direct-view display device, and a projection display device. In particular, the present invention relates to an image display technique capable of adjusting brightness.

  In recent years, in direct view type and projection type display devices, in order to expand the apparent dynamic range (gradation range) of display, it has been studied to adjust the brightness of the light source according to the content to be displayed. .

As a display device that can adjust the brightness of a light source according to the content to be displayed, a display device that can adjust the brightness of the light source itself is known (see, for example, Patent Document 1).
JP-A-3-179886 (Page 3-4, Fig. 1)

  In the conventional method, there is a problem that the emission spectrum is changed by adjusting the brightness of the light source, and the color of the display image is changed.

  The present invention has been made in order to solve the above-described problems, and includes a display device, a direct-view display device, and a projection display device that expand the apparent dynamic range and do not affect the color. The purpose is to provide.

  In order to achieve the above object, a display device of the present invention is a display device that includes a light modulation unit having a plurality of pixels and displays an image according to an image signal, and a light source that illuminates the light modulation unit; Light source driving means for controlling the amount of light emitted from the light source by adjusting the time during which the light source is lit at a predetermined luminance per unit time, and the light source driving means is provided per unit time. And adjusting the lighting time for the light source to turn on with a predetermined luminance, and controlling the light source to turn on with a luminance lower than the predetermined luminance at a time other than the lighting time.

  The display device of the present invention is a display device that includes a light modulation unit having a plurality of pixels and displays an image according to an image signal, and includes a light source that illuminates the light modulation unit, and a light source per unit time. Is provided with light source driving means for controlling the amount of light emitted from the light source by adjusting the lighting time with a predetermined luminance.

That is, in the display device of the present invention, the light emitted from the light source irradiates the display device to form an image based on the image signal. In this display device, when displaying a dark image, the light source driving means adjusts the time during which the light source is turned on with a predetermined luminance based on the image signal, thereby allowing the light amount emitted from the light source per unit time. Is controlling.
Therefore, if an image signal of a dark image is input, the time for which the light source is turned on with a predetermined luminance is shortened, and the amount of light emitted from the light source per unit time is reduced, and the displayed image is also darkened. On the contrary, if an image signal of a bright image is input, the time during which the light source is turned on with a predetermined luminance is lengthened, and the amount of light emitted from the light source per unit time increases, and the displayed image becomes bright. Therefore, the range of gradations that can be displayed is widened, and the apparent dynamic range can be expanded.

Further, since the light emission amount of the light source during the lighting time is constant, the emission spectrum does not change and the color of the display image does not change.
Furthermore, since the lighting time of the light source is controlled within a time width within one unit time, the display method becomes an impulse-type display and the moving image visibility can be improved.

In the display device of the present invention, the light source driving means includes a luminance extracting means for extracting a parameter characterizing the brightness of the screen from the image signal, and the light source driving means determines the amount of light emitted from the light source based on the parameter. It is desirable to control.
Since the amount of light emitted from the light source is controlled based on a parameter that characterizes the brightness of the screen, the amount of light is controlled to an amount that displays an image with appropriate brightness.
Therefore, the light amount adjustable range of the light source can be used without waste, and the dynamic range of the displayed image can be further expanded.

In the display device according to the present invention, it is desirable to perform control so that image processing is added to the image signal displayed by the light modulation means based on the parameter characterizing the brightness of the screen.
By adding such processing to the video signal in addition to the brightness control of the light source, the contrast of the displayed video as well as the screen brightness can be increased, so that the video reproduction capability can be further enhanced.

In the display device of the present invention, the light source driving means controls the number of times the light source is turned on once per unit time, and also controls the length of one lighting time so that the light source is emitted per unit time. It is desirable to control the amount of light emitted from the projector.
In the display device of the present invention, the light source driving means controls the lighting of the light source once per unit time and the lighting time thereof. That is, the amount of light emitted from the light source per unit time can be controlled by the length of the lighting time of the light source.

In the display device of the present invention, the light source driving means controls the number of times the light source is turned on to a predetermined number of times of 2 or more per unit time, and controls the length of the lighting time per time, It is desirable to control the amount of light emitted from the light source per unit time.
Since the number of times of lighting per unit time is a predetermined number of times of two or more, the lighting frequency of the light source is higher than the image frequency. When the lighting frequency of the light source is increased, flickering of the light source is less likely to be perceived by human eyes, and flicker (image flicker) can be suppressed.

In the display device of the present invention, the light source driving means fixes the lighting time of the light source to a predetermined lighting time, controls the number of lighting times per unit time, and emits light from the light source per unit time. It is desirable to control the amount of light. More preferably, the predetermined lighting time is a time from when the light source is turned on until the luminance becomes the same as the luminance at the time of steady lighting (hereinafter referred to as a minimum lighting time).
Since the amount of light emitted from the light source is controlled by fixing the lighting time of one time to the minimum lighting time and controlling the number of times of lighting per unit time, the lighting frequency of the light source is significantly higher than the image frequency. It has become. When the lighting frequency of the light source is significantly increased, flickering of the light source is not perceived by human eyes, and flicker due to flickering of the light source can be eliminated.

In the display device according to the present invention, it is desirable that the light source driving unit performs control to light the light source constantly when the brightness of the image signal is maximum.
Since the light source is always turned on when the brightness of the image signal is maximum, that is, when the brightness of the image is maximum, there is no flicker of the brightness of the image. When there is no flickering in the image, the eye is not burdened and it is hard to get tired.

In the display device according to the present invention, it is preferable that the light source driving unit performs control to intermittently light the light source when the brightness of the image signal is maximum.
Even when the brightness of the image signal is maximum, the light source is intermittently lit, so not only during dimming but also when the brightness of the image is maximum, it becomes an impulse-type display and improves video visibility Can do.

In the display device according to the present invention, the light source driving unit adjusts a lighting time during which the light source is lit at a predetermined luminance per unit time, and the light source exceeds the predetermined luminance at a time other than the lighting time. It is desirable to control so that the light is lit at a low luminance. More preferably, the low luminance is the luminance when the light source is always turned on when the brightness of the image signal is the darkest.
Even during times other than the above lighting time, the light source is turned on at the brightness when the light source is always turned on when the brightness of the image signal is the darkest (hereinafter referred to as the minimum brightness). The difference becomes smaller. When the blink difference is small, the flicker is reduced and the eyes are less tired. In particular, flicker in dark images is reduced.

The display device of the present invention can be used for a display device provided with a light modulation device and a display device of a projection display device that projects light modulated by the light modulation device.
By using the display device as a projection display device, the apparent dynamic range can be expanded and the power consumption can be reduced.

The projection display device includes three light modulation elements each corresponding to the three primary colors and three light sources capable of emitting the respective color lights, and the light source driving means turns on the light source for each color light of a different color. It is desirable to shift.
By shifting the lighting timing of the light source for each color light of different colors, the peak of the power consumption due to the lighting of the light source can be dispersed, the peak power consumption of the projection display device as a whole can be reduced, and the power consumption can be further reduced be able to.

The projection display device comprises three light modulation elements corresponding to the three primary colors and three light sources capable of emitting the respective color lights, and the light source driving means matches the lighting timings of all the light sources. Is desirable.
By matching the lighting timings of all the light sources, different color lights are emitted at the same time, so that it is possible to prevent a color breakup phenomenon in which each color light appears to be temporally separated on the image.

In the projection display device of the present invention, a light emitting diode (Light Emitting Diode, hereinafter referred to as LED) capable of emitting different color lights can be used as a light source.
Currently, high-power LEDs are provided for each color light of R, G, and B, and these types of LEDs can be arranged in an array in a planar or curved manner. Further, since the LED can be blinked relatively easily at a high frequency, a light source suitable for the projection display device of the present invention can be obtained.

The display device of the present invention can be used in a display device of a direct-view display device that includes a light source and a display device that modulates light from the light source.
By providing the display device in the display device of the direct-view display device, the apparent dynamic range can be expanded and the power consumption can be reduced.

[First example of the first embodiment]
The first example of the first embodiment of the present invention will be described below with reference to FIGS.
In this embodiment, an example of a three-plate projection type liquid crystal display device is shown. FIG. 1 is a schematic diagram showing the overall configuration of a projection display device 10, wherein reference numerals 11, 12, and 13 denote LEDs (light sources), 21, 22, and 23 denote liquid crystal light valves (display devices), and 25 denotes a cross dichroic prism. , 31 is a projection lens (projection means), and 35 is a light source control section (light source drive means).

  As shown in FIG. 1, the projection display device 10 according to the present embodiment is emitted from a plurality of LEDs 11, 12, and 13 and LEDs 11, 12, and 13 that can emit R, G, and B color lights, respectively. Liquid crystal light valves 21, 22, and 23 corresponding to R, G, and B, respectively, that modulate color light, a cross dichroic prism 25 that combines the modulated color lights, and a projection lens 31 that projects the combined light flux on the screen S And a light source control unit 35 that performs blinking control of the LEDs 11, 12, and 13. Note that a means for equalizing illumination and a means for aligning the polarization direction, which are not described in this embodiment, may be provided between the LED light source and the liquid crystal light valve.

  The LEDs 11, 12, and 13 are arranged so as to face each surface of the cross dichroic prism 25 and to emit each color light toward the cross dichroic prism 25. The liquid crystal light valves 21, 22, and 23 are disposed between the LEDs 11, 12, and 13 and the cross dichroic prism 25, respectively.

The liquid crystal light valves 21, 22, and 23 are composed of a liquid crystal panel, an incident side polarizing plate (not shown), and an outgoing side polarizing plate (not shown). The liquid crystal panel includes a thin film transistor (pixel switching element) as a pixel switching element. A TN (Twisted Nematic) mode active matrix transmissive liquid crystal cell using a Thin Film Transistor (hereinafter abbreviated as TFT) is used.
The cross dichroic prism 25 has four right-angle prisms bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface thereof.

  The light source control unit 35 is provided with a luminance extraction unit (luminance extraction means) 36 that extracts the maximum luminance of the image from the input image signal and outputs the maximum luminance data to the light source control unit 35.

Next, the operation of the projection display device 10 having the above configuration will be described.
As shown in FIG. 1, the color lights R, G, and B respectively emitted from the LEDs 11, 12, and 13 are incident on the liquid crystal light valves 21, 22, and 23 corresponding to the respective color lights.
Each incident color light is modulated by the liquid crystal light valves 21, 22, and 23 based on the image signal and is emitted to the cross dichroic prism 25. The modulated color lights are combined in the cross dichroic prism 25 and emitted to the projection lens 31. The projection lens 31 enlarges and projects the combined color lights toward the screen S.

Next, lighting control of the LEDs 11, 12, and 13, which is a feature of the present invention, will be described.
As shown in FIG. 1, the image signal is input to the luminance extraction unit 36, and the luminance extraction unit 36 determines the maximum gradation per field (unit time) of the image signal, that is, the maximum luminance of the image per field. Calculated. The calculated maximum luminance is output to the light source control unit 35.

FIG. 2 is a time chart showing the lighting and extinguishing timings of the LEDs 11, 12, and 13 in this embodiment.
The light source driving unit 35 first obtains a necessary light amount per field from the inputted maximum luminance. Then, when the LEDs 11, 12, and 13 emit light with the luminance M when the rated current is passed, the lighting time T necessary to emit the above-described light amount is obtained.
When the lighting time T is obtained, the light source driving unit 35 turns on the LEDs 11, 12, and 13 at the same time as shown in FIG.

  For example, when the maximum luminance calculated from the image signal increases, the amount of light required per field increases. Since the upper limit of the luminance of the LEDs 11, 12, and 13 is the luminance when the rated current is passed as described above, the lighting time becomes longer in order to increase the amount of light per field. That is, as indicated by the two-dot chain line in FIG. 2, the lighting times of the LEDs 11, 12, and 13 in one field become longer.

FIG. 3 is a graph showing the required brightness calculated from the maximum brightness and the ratio of the lighting time per field.
As shown in FIG. 3, the lighting times of the LEDs 11, 12, and 13 in one field are set so as to become longer in a quadratic function when the brightness calculated from the maximum brightness becomes brighter (the amount of light increases). Yes. Also, when the maximum brightness is displayed, the ratio of the lighting time per field is not 100%, and the LEDs 11, 12, and 13 are intermittently lit.

According to the above configuration, the amount of light for irradiating the liquid crystal light valves 21, 22, and 23 per field is determined according to the maximum luminance of the image signal, and the LEDs 11, 12, and 13 are turned on per field from this amount of light. Time to do is required.
That is, if the maximum luminance of the image signal is low, the time for which the LEDs 11, 12, 13 are lit per field is shortened and the displayed image becomes dark, and if the maximum luminance of the image signal is high, the LEDs 11, 12, 13 is turned on per field for a long time, and the displayed image becomes brighter. Therefore, the range of gradations that can be displayed is widened, and the apparent dynamic range can be expanded.

More specifically, the LEDs 11, 12, and 13 are lit at the same time once per field. That is, since the LEDs 11, 12, and 13 are turned on and off at the same time, it is possible to prevent the colors of the displayed image from appearing temporally separated.
Further, since the lighting times of the LEDs 11, 12, and 13 are controlled with a time width of less than one field, the image switching method is an impulse-type display, and the moving image visibility can be improved.

  The lighting times of the LEDs 11, 12, and 13 are determined so that only a necessary amount of light can be emitted based on the maximum luminance of the image signal. At this time, since the amount of light emitted from the light source within the lighting time is always constant, the emission spectrum does not change, and the color of the image can be prevented from changing.

  Further, even when the maximum luminance of the image signal is maximum, the LEDs 11, 12, and 13 are controlled to be intermittently lit. Therefore, even when the brightness of the image is maximum, the moving image visibility can be ensured.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
The basic configuration of the projection display device of the present embodiment is the same as that of the first embodiment, but the blinking patterns of the LEDs 11, 12, and 13 are different. In this embodiment, the LEDs 11 and 12 are used with reference to FIG. , 13 will be described only, and the description of the light source and the like will be omitted.

The operation of the projection display device 10 having the above configuration will be described.
FIG. 4 is a time chart showing the lighting and extinguishing timings of the LEDs 11, 12, and 13 in this embodiment.
First, the light source driving unit 35 obtains a light amount necessary for one field from the maximum luminance input as described above, and obtains a lighting time T necessary for emitting the light amount. When the lighting time T is obtained, as shown in FIG. 4, the light source driving unit 35 divides the lighting time into two, lights up twice per field and for the lighting time T / 2 described above, and the LEDs 11, 12, 13 is turned on simultaneously.

  Further, when the maximum luminance calculated from the image signal increases, the light source driving unit 35 lengthens the lighting time in order to increase the amount of light emitted from the LEDs 11, 12, and 13 per field. That is, as indicated by a two-dot chain line in FIG. 4, the lighting time of the LEDs 11, 12, 13 at each lighting is long.

  According to the above configuration, since the number of times the LEDs 11, 12, and 13 are turned on per field is set to twice, the lighting frequency of the LEDs 11, 12, and 13 is approximately twice the image frequency. As described above, when the lighting frequencies of the LEDs 11, 12, and 13 are increased, flickering of the LEDs 11, 12, and 13 is less likely to be perceived by human eyes, and flicker (flickering of images) can be suppressed.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
The basic configuration of the projection display device of the present embodiment is the same as that of the first embodiment, but the blinking patterns of the LEDs 11, 12, and 13 are different. Therefore, in this embodiment, the LEDs 11 and 12 are used with reference to FIG. , 13 will be described only, and the description of the light source and the like will be omitted.

The operation of the projection display device 10 having the above configuration will be described.
FIG. 5 is a time chart showing the lighting and extinguishing timings of the LEDs 11, 12, and 13 in the present embodiment.
First, the light source driving unit 35 obtains a light amount necessary for one field from the maximum luminance input as described above, and obtains a lighting time T necessary for emitting the light amount. When the lighting time T is obtained, the light source driving unit 35 divides the lighting time T by a minimum lighting time t described later (divided into four in FIG. 5), as shown in FIG. The LEDs 11, 12, and 13 are turned on for the number of times obtained by dividing the lighting time T per field by the minimum lighting time t, and are turned on for the minimum lighting time t for each lighting, and the LEDs 11, 12, and 13 are simultaneously turned on. Is done.
The minimum lighting time t here is a time from when the LEDs 11, 12, 13 are turned on until the luminance becomes the same as the luminance during steady lighting.

  In addition, when the average luminance calculated from the image signal is increased, the light source driving unit 35 increases the number of times of lighting in order to increase the amount of light emitted from the LEDs 11, 12, and 13 per field. That is, as indicated by a two-dot chain line in FIG. 5, the number of times the LEDs 11, 12, and 13 are turned on in one field increases.

  According to said structure, the light source drive part 35 is radiate | emitted from a light source by fixing the lighting time of 1 time of LED11, 12, 13 to the minimum lighting time t, and controlling the frequency | count of lighting per field. The amount of light is controlled. Therefore, the lighting frequency of the LEDs 11, 12, and 13 is significantly higher than the image frequency, the blinking of the LEDs 11, 12, and 13 is not perceived by human eyes, and flicker due to the blinking of the LEDs 11, 12, and 13 can be eliminated. .

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The basic configuration of the projection type display device of this embodiment is the same as that of the first embodiment, but the blinking patterns of the LEDs 11, 12, 13 are different. Therefore, in this embodiment, the LEDs 11, 12 are used with reference to FIG. , 13 will be described only, and the description of the light source and the like will be omitted.

The operation of the projection display device 10 having the above configuration will be described.
FIG. 6 is a time chart showing the lighting and extinguishing timings of the LEDs 11, 12, and 13 in the present embodiment.
The light source driving unit 35 first obtains a necessary light amount per field from the input maximum luminance as described above. At this time, the lower limit luminance L is set in the adjustment range of the light emission amount, and the luminance L is obtained by steady lighting of the light source. Considering this, the light source driving unit 35 obtains a lighting time T1 necessary for emitting a necessary amount of light.
When the lighting time T1 is obtained, as shown in FIG. 6, the light source driving unit 35 always lights the LEDs 11, 12, and 13 with the luminance L, and the luminance M when the rated current is passed only once per field. Lights on. The lighting time of the brightness M is T1 described above, and the LEDs 11, 12, and 13 are simultaneously turned on with the brightness M.

  Further, when the maximum luminance calculated from the image signal is increased, the light source driving unit 35 lengthens the time for lighting at the luminance M in order to increase the amount of light emitted from the LEDs 11, 12, and 13 per field. In other words, as indicated by the two-dot chain line in FIG.

  According to the above configuration, even when the LEDs 11, 12, and 13 are turned off in the other embodiments, the LEDs 11, 12, and 13 are lit at the luminance L, so that the brightest display in one field is the most brightest display. The ratio with the dark display, that is, the difference in blinking brightness becomes small. When the blinking difference is reduced, the flicker due to blinking of the image is reduced, and the eyes are less tired. In particular, flicker in dark images is reduced.

[Fifth embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG.
The basic configuration of the projection type display device of this embodiment is the same as that of the first embodiment, but the blinking patterns of the LEDs 11, 12, 13 are different. Therefore, in this embodiment, the LEDs 11, 12 are used with reference to FIG. , 13 will be described only, and the description of the light source and the like will be omitted.
First, the light source driving unit 35 obtains a light amount necessary for one field from the maximum luminance input as described above, and obtains a lighting time T necessary for emitting the light amount. When the lighting time T is obtained, the light source driving unit 35 lights the LEDs 11, 12, 13 once per field as shown in FIG. At the same time, the LEDs 11, 12, and 13 are lit at different timings so that they are not lit simultaneously.

  According to the configuration described above, the lighting timing of the LEDs 11, 12, 13 is shifted for each color light of different colors to disperse the peak of power consumption due to the lighting of the LEDs 11, 12, 13, and the projection display device 10 as a whole. The peak power consumption can be reduced, and the power consumption can be further reduced.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
In this embodiment, an example of a direct-view liquid crystal display device is shown. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
FIG. 8A is a schematic front view showing the overall configuration of the direct-view display device 50, and FIG. 8B is a schematic side view of the direct-view display device 50.

  As shown in FIG. 8, the direct-view display device 50 of the present embodiment includes an LED (light source) 51 that can emit white light, and a liquid crystal cell (display device) 52 that modulates the white light emitted from the LED 51. The light guide 53 that guides the white light emitted from the LED 51 to the liquid crystal cell 52 and the light source driving unit 35 that controls the LED 51 are schematically configured.

The LED 51 is arranged at the upper end of the light guide 53 so that white light can be emitted toward the light guide 53.
The light guide 53 is formed to have substantially the same dimensions as the liquid crystal cell 52 in a front view, and is inclined so that a rear surface 54 approaches the front from the top to the bottom in a side view. Yes.

  The liquid crystal cell 52 includes an incident side polarizing plate (not shown) and an outgoing side polarizing plate (not shown). The liquid crystal cell 52 uses a TN (twisted nematic) mode active matrix transmission type liquid crystal cell using a thin film transistor (hereinafter abbreviated as TFT) as a pixel switching element.

Next, the operation of the direct-view display device 10 having the above configuration will be described.
The white light emitted from the LED 51 enters the light guide 53 from the upper end of the light guide 53 as shown in FIG. The white light incident in the light guide 53 propagates while reflecting in the light guide 53, and a part of the white light is reflected on the rear surface 54 having an inclination angle and propagates toward the liquid crystal cell 52. . Each color light incident on the liquid crystal cell 52 is modulated by the liquid crystal cell 52 based on an image signal to form an image.

  As shown in FIG. 8, the image signal is input to the luminance extraction unit 36, and the luminance extraction unit 36 calculates the maximum gradation per field of the image signal, that is, the maximum luminance of the image per field. The calculated maximum luminance is output to the light source control unit 35.

FIG. 9 is a time chart showing lighting and extinguishing timings of the LED 51 in the present embodiment.
The light source driving unit 35 first obtains a necessary light amount per field from the inputted maximum luminance. Then, when the LED 51 emits light at the luminance M when a rated current is passed, the lighting time T necessary to emit the above-described light amount is obtained.
When the lighting time T is obtained, the light source driving unit 35 lights up once per field and for the lighting time T described above, as shown in FIG.

FIG. 10 is a graph showing the required brightness calculated from the average luminance and the ratio of lighting time per field.
As shown in FIG. 10, the lighting time of the LED 51 in one field is set so as to increase in a quadratic function when the brightness calculated from the maximum brightness becomes brighter (the amount of light increases). Further, when the maximum brightness is displayed, the ratio of the lighting time per field is 100%, and the LED 51 is always lit.

  According to the above configuration, when the maximum luminance of the image signal is maximum, that is, when the brightness of the image is maximum, the LED 51 is always lit, so that there is no flickering of the brightness of the image. When there is no flickering in the image, the eye is not burdened and it is hard to get tired.

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 display device is described as being adapted to a liquid crystal light valve. However, the display device is not limited to the liquid crystal light valve, and is not limited to a liquid crystal light valve. It can be applied to various other spatial light modulators such as a mirror device.
In the above embodiment, the description has been made by adapting to an LED using a light source. However, the present invention is not limited to using an LED as a light source, but can be applied to various other light sources such as a high-pressure mercury lamp. Is something that can be done.

It is a schematic block diagram which shows the projection type display apparatus of the 1st Embodiment of this invention. It is a time chart which shows the blink timing of each LED in a 1st Example. It is the graph which showed the brightness required for the image in a present Example, and the ratio of lighting time. It is a time chart which shows the blinking timing of each LED in a 2nd Example. It is a time chart which shows the blink timing of each LED in a 3rd Example. It is a time chart which shows the blinking timing of each LED in a 4th Example. It is a time chart which shows the blink timing of each LED in a 5th Example. It is a schematic block diagram which shows the direct view type display apparatus of the 2nd Embodiment of this invention. It is a time chart which shows the blinking timing of LED in 2nd Embodiment. It is the graph which showed the brightness required for the image in 2nd Embodiment, and the ratio of lighting time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Projection type display apparatus 11, 12, 13 ... LED (light source) 21, 22, 23 ... Liquid crystal light valve (display apparatus), 31 ... Projection lens (projection means), 35 ... Light source control unit (light source driving means) 36 ... Luminance extraction unit (luminance extraction means) 50 ... Direct view type display device 51 ... LED (light source) 52 ... Liquid crystal light valve (Display device)

Claims (5)

A display device comprising a light modulation means having a plurality of pixels and displaying an image according to an image signal,
A light source that illuminates the light modulating means;
Light source driving means for controlling the amount of light emitted from the light source by adjusting the time for the light source to turn on the entire surface of the light modulation means with a predetermined luminance per unit time, and
As the light source, three light sources that emit different colored lights are used,
As the light modulation means, three light modulation means for modulating the three colored lights emitted from the three light sources based on image signals respectively,
The light source driving means controls the amount of light emitted from the three light sources by adjusting the time during which the three light sources are lit at a predetermined luminance per unit time,
Said light source driving means, 1 together with the three light sources per unit time is adjusted lighting time lights at a predetermined luminance, the three light sources to a time other than the lighting time at a lower brightness than the predetermined luminance Control to light up, and
It said light source driving means, when the brightness of the image signal is maximum, have lines control to intermittently light the light source, further,
The display device , wherein the light source driving means shifts the lighting timing of each light source for each color light of a different color . The light source driving means comprises a luminance extracting means for extracting a parameter characterizing the brightness of the screen from the image signal;
The display device according to claim 1, wherein the light source driving unit controls the amount of light emitted from the light source based on the parameter extracted by the luminance extraction unit.   The display device according to claim 2, wherein the image signal displayed by the light modulation unit is controlled to perform image processing based on a parameter characterizing brightness of the screen.   4. A projection type display apparatus comprising a display unit according to claim 1 and a projection unit for projecting light modulated by the light modulation unit. The projection display device according to claim 4 , wherein the light source is a light emitting diode capable of emitting different color lights.

Images