JPH1165528A - Display device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the contrast ratio of a displayed image and to reduce power consumption by changing the electric power supplied to a light source, according to a video signal. SOLUTION: The high-frequency component of a boosted video signal is removed by a high-frequency cut filter 202 in a light source control circuit part 208. The maximum signal among three primary colors is detected by a maximum value detecting circuit 203. The maximum value detecting circuit 203 has a peak-holding function for holding the detected maximum value. After the output signal of the maximum value detecting circuit 203 has been inputted to a high-frequency cut filter 204 and the change of the signal is made to be gradual, the signal is inputted to the control terminal of an inverter power source 210 of a lamp. The averaged changing amount for the brightness of a screen is obtained and fed back to the light source. By supplying a control signal corresponding to the maximum value of the video signal to the inverter power source 210, the lamp is controlled when the level of video signal is high, namely, so that the brighter the screen is, the brighter the lamp becomes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a display device and a display method. More specifically, the present invention relates to a display device and a display method in which the contrast ratio of a displayed image is high and the power consumption of a light source is low.

[0002]

2. Description of the Related Art In recent years, various display devices which replace conventional cathode ray tubes have attracted attention. As an example, a flat panel display having a backlight, a projection type liquid crystal display device capable of displaying a large screen, and the like can be given. Among these display devices, a projection type liquid crystal display device will be described as an example. A device that forms a two-dimensional pattern of transmission / non-transmission on a liquid crystal panel using a laser beam, a switching device such as a thin film transistor, and the like. To form an electrically transparent / non-transparent two-dimensional pattern. In particular, those using a liquid crystal panel that electrically forms a pattern are expected to be used for large-screen televisions because they can display moving images. In addition to a liquid crystal display, a digital mirror display (DMD) that displays a predetermined image by scanning a micro mirror has been developed.

FIG. 8 is a schematic diagram showing a basic structure of a projection type liquid crystal device using a display panel which operates as a light valve such as a liquid crystal panel. Projection type liquid crystal display device 80
The configuration of 0 is as follows. That is, a halogen lamp 810 provided with a parabolic reflector 811 is provided as a light source. Also, the filter 81
2. Incident side polarizing plate 813, liquid crystal panel 814, exit side polarizing plate 815, field lens 816, projection lens 8.
17 are provided. Further, the halogen lamp 81
0 is connected to the power supply circuit 830 and the liquid crystal panel 814,
A liquid crystal panel drive circuit 820 for driving a liquid crystal panel based on a video signal input to a video signal input terminal 821 from an external video signal source is provided. Projection lens 817
The light emitted from forms a predetermined image on the screen 818.

The operation is as follows. That is, the light emitted from the lamp 810 is reflected by the parabolic reflector 81.
The light is converted into substantially parallel light by 1, the infrared light and the ultraviolet light are cut by the filter 812, and the light becomes white light from which unnecessary invisible band wavelength components have been removed, and is incident on the polarizing plate 813.

The white light incident on the polarizing plate 813 is
The liquid crystal panel 8 is random polarized light while maintaining the light emission characteristics of the liquid crystal panel 10, but is converted into linearly polarized light by the
14 is incident. The liquid crystal panel 814 has a structure in which pixels as display units in which liquid crystal operating in a 90-degree twisted nematic mode is sandwiched between transparent electrodes are two-dimensionally arranged, and the polarization state of transmitted light is two-dimensionally changed. Modulation can be performed.

[0006] In each pixel, a weak voltage is applied to the liquid crystal with respect to the video signal corresponding to the brightest display, and the polarization of the incident light is rotated by 90 degrees. Similarly, a strong voltage is applied to the liquid crystal with respect to the video signal of dark display, the liquid crystal layer does not exhibit optical rotation characteristics, and the incident light is emitted while maintaining the polarization state of linearly polarized light. LCD panel 61
4 is transmitted through the polarizing plate 815 on the output side.
At this time, the change in the polarization state by the liquid crystal panel is converted into a change in the light intensity. As a result, the light from the lamp 810 is appropriately attenuated and modulated into light having a two-dimensional intensity distribution. This light is projected on a screen 818 by a field lens 816 and a projection lens 817,
A predetermined image is formed.

[0007] Many projection display devices actually used realize color display. Such a color display is made possible by a color liquid crystal panel having a color filter. FIG. 9 is a schematic diagram illustrating an example of the arrangement of color filters of a color liquid crystal panel. Here, the light transmission areas provided with red, green, and blue color filters, which are the three primary colors of light, are indicated by letters R, G, and B, respectively. One set of these RGB forms the pixel 901. Then, the liquid crystal in each of the R, G, and B regions of each pixel is driven by a driving voltage corresponding to the intensity of each color, so that color transmittance control can be realized. A liquid crystal panel having such a function is used as the liquid crystal panel 814 shown in FIG. 8, and color display can be realized by supplying three video signals corresponding to RGB from the driver circuit 820.

In addition to the above, various types of projection display devices described in, for example, liquid crystal device handbooks P605 to P610, and Japanese Patent Application Laid-Open No. Hei 7-181487, are examples of projection display devices for realizing color display. There is also an apparatus that realizes color display using a single panel and a microlens disclosed in US Pat. The basic principle of realizing color display is the same. Japanese Patent Application Laid-Open No. 63-243929 discloses a display device that adjusts screen illuminance by detecting reflected light from a screen.

[0009]

However, a projection type display device using a lamp, that is, a display panel for controlling light transmittance or reflectance, is irradiated with light from the lamp, and the emitted light is projected to display an image. Is particularly disadvantageous in the following two points when compared with a self-luminous image display device such as a cathode ray tube (CRT).

The first point is a relationship between brightness of image display and power consumption. In the case of the self-luminous type, when dark display is performed, the energy required for light emission is reduced, so that power consumption is reduced. However, in the method using a lamp, the light emission intensity of the lamp is constant irrespective of the image display, so that the power consumption does not decrease even in the dark display. In other words, there is a possibility that the use of the lamp will waste more power.

The second point is a difference in dynamic range. In the case of the self-luminous type, in black display, the brightness of the display can be reduced to a state close to 0 by reducing the luminous intensity. Therefore, there is a possibility that a very high contrast ratio can be realized. On the other hand, in the method using a lamp, an image is displayed by attenuating the light from the lamp, which can be realized because the light transmittance or light reflectance of the display panel has a certain limit. The contrast ratio is lower than that of the self-luminous type. This appears as a difference in the dynamic range of the displayed screen.

The present invention has been made in view of such a point. That is, an object of the present invention is to provide a display device and a display method with low power consumption, high contrast ratio, and large dynamic range.

[0013]

According to the present invention, there is provided light source control means for varying the power input to the lamp in accordance with the brightness of the screen so as to be bright on a bright screen and dark on a dark screen. The brightness of the screen is the brightness of the portion having the maximum brightness on the display screen. However, it is wasteful to use the brightness of a very small area as a reference, and the means for actually detecting the maximum brightness should first smooth the video signal with a low-pass filter and then detect the maximum value. Is desirable.

It is desirable that the intensity of the video signal applied to the display panel is also changed according to the power applied to the lamp. In a color display device, it is desirable to change not only the intensity of the video signal but also the intensity ratio of the video signals corresponding to the three primary colors. Further, it is desirable that the light emission intensity of the lamp is detected by an optical sensor and the voltage applied to the display panel is changed according to the light amount, instead of being changed according to the power applied by the lamp. In particular, in a color display device, it is desirable that a color sensor is also provided as a sensor, and that the intensity ratio of video signals corresponding to the three primary colors applied to the display panel is also changed.

[0015]

According to the present invention, by changing the power supplied to the light source in accordance with the video signal, the light source itself emits a darker light on a dark screen and the light source itself emits a brighter light on a bright screen. Can be changed.
As a result, the contrast ratio of the displayed image can be improved, and the power consumption can be reduced. At the same time, the life of the lamp can be extended.

At the same time as the power supplied to the lamp is changed, the intensity of the video signal supplied to the display panel is darker when the power is larger than when the power supplied to the lamp is constant and smaller when the power is small. By changing in the direction in which the lamp becomes brighter, it is possible to prevent the change in lamp brightness from appearing unnatural on the display screen.

Further, in many lamps, when the supplied power is changed, not only the brightness of the light emission but also the color changes. By changing the intensity ratio of the video signals of the three primary colors supplied to the display panel so as to compensate for the color change of the lamp, the brightness can be changed without changing the display color.

Further, the adjustment of the video signal supplied to the display panel is not performed based on the power supplied to the lamp, but is performed in such a manner that the light emission of the lamp is detected by a sensor and the actual light emission intensity is adjusted. Then better.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a projection display device according to a first embodiment of the present invention. The configuration of the optical system of the display device 100 is substantially the same as that of the conventional projection display device shown in FIG. That is, the halogen lamp 1
10, radiation surface reflector 111, filter 112 for cutting infrared and ultraviolet components, and polarizing plate 11 on the incident side
3, a liquid crystal panel 114, an output side polarizing plate 115, a field lens 116, and a projection lens 117 are provided. A predetermined image is displayed on the screen 118 by these optical systems.

A feature of the display device according to the present invention resides in that a light source control / video signal correction circuit 150 is provided. The liquid crystal panel drive circuit 120 is connected to an external video signal input terminal 15.
The liquid crystal panel is driven on the basis of the video signal corrected by the light source control / video signal correction circuit 150 instead of the video signal from 1.

A light source control / video signal correction circuit 150
Controls the lamp power supply 130 and adjusts the power supplied to the lamp 110.

FIG. 2 shows a light source control / video signal correction circuit 15.
FIG. 4 is a schematic diagram illustrating a configuration of a zero. The operation will be described below with reference to FIG. First, the video signals of the three primary colors RGB are input to the input terminals 250R, 250G, 250G.
Input from B. These video signals have an amplitude of 0.7V
Analog video signal having a frame frequency of 60H
z, the number of scanning lines is 480, the signal band is approximately 25 MHz, and the horizontal resolution is a signal corresponding to approximately 640 pixels. Since these signal inputs are AC signals, they are converted to D signals by the DC conversion circuit 201 so that the signals can be easily processed.
The signal is converted to a C signal and the amplitude is increased to 5V.

The boosted video signal is supplied to the light source control circuit 2
08, the high frequency component is
2, 202, 202. The high-frequency cut filter 202 cuts, for example, a signal component of 8 MHz or more, and obtains an average intensity spatially with a width of several pixels. The averaging is performed so as not to detect one very small bright spot and to remove high-frequency noise included in the video signal. Next, the maximum value detection circuit 203 detects the maximum signal among the three primary colors. Control of a lamp light source, which will be described later, is performed based on this maximum value. Here, in the maximum value detection circuit 203, 3
The maximum value may be detected for any specific color signal of the primary colors. In this case, it is desirable to detect the maximum value for the green (G) signal having the highest human visibility. Alternatively, the sum of the signals of the three primary colors may be calculated, and the maximum value thereof may be detected.

The maximum value detection circuit 203 has a so-called peak hold function for holding the maximum value detected in this way. However, if the detected maximum value is held forever, its output will be constant at that value, so an appropriate reduction circuit is required. In the present embodiment, the time constant can be appropriately determined within a range in which the lower limit is set to a value similar to that of the high-frequency cut filter 204 described later and the upper limit is set to about several seconds. The detected maximum value is attenuated based on the time constant determined in this way.

The output signal of the maximum value detection circuit 203 is input to the high-frequency cut filter 204, after which the change of the signal is made gentler, and then input to the control terminal of the inverter power supply 210 of the lamp. In general, when the displayed screen is averaged and viewed as a whole, it becomes brighter or darker every moment. The averaged change in the brightness of the screen is obtained and fed back to the light source. The range in which averaging is performed can be determined as appropriate depending on the band of the filter. In this way, by supplying the control signal corresponding to the maximum value of the video signal to the inverter power supply 210, when the video signal level is high, that is, when the screen is "brighter", the lamp is controlled to be "brighter". be able to.

Here, the high-frequency cut filter 204
Has a characteristic of cutting a signal component of, for example, 20 Hz or more. Accordingly, only the frequency components sufficiently lower than the frame frequency (60 Hz) are used for controlling the lamp power, and the display correction operation of the liquid crystal panel described later sufficiently follows the change in the light emission intensity of the lamp. I can do things. In addition, if the change in the light emission of the lamp occurs in a short time, it appears as flickering, so that it also serves to prevent flickering.

The signal output from the high-frequency cut filter 204 is input to the control terminal of the inverter power supply 210 of the lamp, and is input again to the video signal correction circuit 206 via the high-frequency cut filter 205 as a control signal. You.

FIG. 3 is a schematic diagram showing the configuration of the video signal correction circuit 206. As shown in the figure, the video signal correction circuit 206 corrects the voltage for driving the liquid crystal panel based on the input control signal, and also corrects the voltage based on the light transmittance characteristic with respect to the applied voltage of the liquid crystal panel ( (Γ correction for liquid crystal) is also performed.

The operation will be described below with reference to FIG. The video signal correction circuit includes input terminals 302R and 302R.
G and 302B, the three primary color video signals of analog signals are converted into three sets of analog / digital conversion circuits 303 and 3.
The signals are respectively converted into digital signals by 03 and 303.
And a correction unit 3 having a data table for γ inverse correction.
04 converts the signal into a signal proportional to the display intensity.
This is because gamma correction is performed on the assumption that a normal video signal is displayed on a CRT, and since the voltage of the video signal and the display intensity are not proportional, it is difficult to correct the signal corresponding to the lamp power later. That's why.

The correction control signal input from the input terminal 300 is also converted into a digital signal by the analog / digital conversion circuit 301. Then, by inputting the relationship between the correction control signal measured in advance and the change in the light emission intensity of the lamp into the conversion table 310, a predicted value of the light emission intensity is obtained. This emission intensity is constituted by conversion tables 310R, 310G, 310B for each of the three primary colors, so that not only the luminance of the lamp but also a change in color can be obtained. This is because the lamp used in this embodiment is a halogen lamp, and when the power is increased, the temperature of the filament, which is the light emitting portion of the lamp, rises to increase the luminous intensity. At this time, the color temperature also rises and the color changes. That's why.

Now, the three conversion tables 310R, 31
From the output terminals of 0G and 310B, not the emission intensity itself, but a signal corresponding to the inverted value of the emission intensity is output. This output is added by the adder circuits 305, 305, and 305 to the γ inverse corrected signal of the video signal. As described above, by adding the inversion value of the light emission intensity to the video signal, the light attenuation of the liquid crystal panel is increased when the lamp is “bright”, and the light of the liquid crystal panel is increased when the lamp is “dark”. Correct so that the amount of attenuation becomes weaker. That is, when the lamp is “bright”, the liquid crystal panel is “darkened”, and when the lamp is “dark”, the liquid crystal panel is corrected to be “bright”. According to the present invention, by driving the lamp and the liquid crystal panel in such a reverse interlocking relationship, the dynamic range and the contrast ratio of the display image are improved while maintaining the brightness of the entire screen constant. be able to.

The output of the addition circuit 305 is the correction table 3
06R, 306G and 306B. In these correction tables, according to the voltage correction table based on the light transmittance characteristic with respect to the voltage applied to the liquid crystal panel, when input to the liquid crystal panel, the intensity of the video signal is corrected to be proportional to the transmittance.

Correction tables 306R, 306G, 306
The signal output from B is finally converted into an analog signal by digital / analog conversion circuits 307, 307, 307, and output to the liquid crystal panel drive circuit 220 via output terminals 320R, 320G, 320B.

To compare the performance of the display device according to the present invention with that of the conventional projection display device, the inventor prototyped the projection display device of the present embodiment and did not control the lamp. The displayed image was compared and evaluated in the case where the lamp control was performed. As a result, the contrast ratio in the case where the lamp control was not performed was about 200: 1. It turned out that it could be improved. In particular, according to the present invention, on a dark screen, it was possible to clearly display a darker screen with a high contrast ratio, and it was found that the image quality was significantly improved.

It was also confirmed that the power consumption of the lamp was reduced according to the present invention. That is, when the lamp control is not performed, the power consumption of the halogen lamp 110 is about 4
In contrast to the power consumption of 00 W, the average value of the power consumption could be reduced to about 320 W by performing the lamp control. In the projection type image display device, since the power consumption of the lamp is particularly large, the power consumption reduction effect obtained by applying the present invention is particularly effectively obtained.

Further, by reducing the power consumption of the lamp as described above, the calorific value can be reduced, and the projection display device can be made smaller and lighter than before. That is, the convection space for heat radiation and the air cooling device can be simplified as compared with the related art. Further, with a decrease in the amount of heat generated, thermal deterioration of optical components such as a liquid crystal panel or an electric circuit portion is reduced, and long-term reliability can be improved. Furthermore, the life of the lamp can be extended.

Next, a second embodiment of the present invention will be described. FIG. 4 is a schematic configuration diagram of a projection display device according to a second embodiment of the present invention. Display device 4 shown in FIG.
The optical system No. 00 includes a metal halide lamp 410, a parabolic reflector 411, a filter 412 for cutting off infrared rays and ultraviolet rays, lens arrays 461 and 462 for equalizing illumination, a condenser lens 463, a polarizing plate 413 on the incident side, and a liquid crystal panel 414. , An output side polarizing plate 415, a field lens 416, and a projection lens 417. The screen is not shown in FIG.

The optical system shown in the figure differs from the first embodiment in that a metal halide lamp is used as a lamp instead of a halogen lamp, and lens arrays 461 and 462 and a condenser lens 46 for uniform illumination.
3 is used.

The liquid crystal panel drive circuit 420 has a light source control /
The liquid crystal panel 414 is driven based on the video signal supplied from the video signal correction circuit 450. The lamp power supply 430 adjusts the power supplied to the lamp 410 according to a control signal from the lamp power / video signal correction circuit 450.

FIG. 5 shows a light source control / video signal correction circuit 45.
FIG. 4 is a schematic diagram illustrating a configuration of a zero. The difference from the light source control / video signal correction circuit 150 of the above-described first embodiment is that the output of the second high frequency cut filter 505 of the light source control circuit unit 508 is output only to the lamp power supply, and 4 in that output signals from the three optical sensors 452R, 452G, and 452B shown in FIG. 4 are input to the signal correction circuit 506. Therefore, apparently, the correction of the video signal and the control of the lamp power are performed independently. However, actually, also in the present embodiment, the correction of the video signal is performed in relation to the control of the lamp power. The reason is that the video signal correction circuit 506 determines the brightness of the lamp 410 by the light sensor 45.
This is because the sensing and control are performed by the control unit 2.

FIG. 6 is a schematic diagram showing the configuration of the video signal correction circuit 506. The operation is as follows. The three primary color video signals of the analog signals input from the input terminals 1002R, 1002G, and 1002B are converted into analog / digital conversion circuits 1003, 1003, and 1003.
Respectively to convert to digital signals. Then, data tables 1004, 1004, 1004 for γ inverse correction
Is converted into a signal proportional to the display intensity. This is the same as the video signal correction circuit 206 shown in FIG.

Now, the three input terminals 1000R, 100R
0G and 1000B have optical sensors 452R and 452R, respectively.
Light intensity signals from 52G and 452B are input. The optical sensors 452R, 452G, 452B are red,
It has green and blue color filters so that the intensity of light corresponding to the three primary colors can be sensed. These optical sensors, as shown in FIG.
2 are arranged. This is lamp 410
This is for sensing light that is slightly irregularly reflected when light from the lens passes through the lens array 462. Here, it is important to detect light at a position closer to the lamp than the liquid crystal panel on the optical path in order to measure the brightness of the lamp without being substantially affected by the display state of the liquid crystal panel 414. It is.

The intensity signals of the three primary colors of the lamp, which are input to the video signal correction circuit 506 by the optical sensor, are inverted by the inverting amplifiers 1003, 1003, and 1003. Is converted to Further, the inverting amplifiers 1003 can set the amplification factors, respectively, and can correct that the sensitivity of the optical sensor differs depending on the color. The outputs of these inverting amplifiers are analog / digital conversion circuits 1004, 10
The signal is converted into a digital signal by the signals 04 and 1004. Subsequent signal processing is the same as that of the video signal correction circuit shown in FIG. 3, and is added to the video signal by the adders 1005, 1005, and 1005, and the voltage based on the light transmittance characteristic with respect to the applied voltage of the liquid crystal panel. Correction table 1006
By R, 1006G, and 1006B, when input to the liquid crystal panel, the intensity of the video signal is corrected so as to be proportional to the transmittance. Finally, the digital / analog conversion circuit 100
The signal is converted into an analog signal by 7, 1007, 1007 and output to the liquid crystal panel drive circuit 520 via the signal terminals 1020R, 1020G, 1020B.

In order to compare the performance with the conventional projection type display device, the present inventor also prototyped the projection type display device of the present embodiment, and evaluated the case where the lamp was not controlled and the case where the lamp was controlled. did. As a result, as in the previous case,
The contrast ratio without lamp control is about 20
In contrast to 0: 1, it was found that the contrast ratio could be improved to about 400: 1 by performing lamp control. In particular, according to the present embodiment, it is possible to display sharply with a high contrast ratio, and it is possible to feed back a change in the color temperature due to the control of the light amount of the lamp. It was also found that the color reproducibility was extremely good.

Further, according to the present embodiment, since the light emission spectrum of the lamp can be constantly monitored by the optical sensor, it is possible to detect and feed back a change in the color temperature due to the aging of the lamp. Therefore, it is possible to prevent a change in the color of the displayed image due to the deterioration of the lamp.

Also in this embodiment, it was confirmed that the power consumption of the lamp was reduced. That is, when the lamp control is not performed, the power consumption of the metal halide lamp 410 is about 250 W and is always a constant value, whereas the average value of the power consumption is obtained by performing the lamp control.
It could be reduced to about 190W. As described above, various effects by reducing the lamp power consumption can be obtained in the same manner as in the above-described embodiment.

Next, a third embodiment of the present invention will be described. FIG. 7 is a schematic configuration diagram of a direct-view display device according to a third embodiment of the present invention. Display device 7 shown in FIG.
00 is a cold-cathode tube lamp 710 serving as a light source, a reflecting plate 71
1, a light guide plate 712, a prism sheet 713, and a liquid crystal panel 714. The liquid crystal panel 714 has polarizing plates attached to both sides thereof.

The light emitted from the lamp 710 is reflected by the reflection plate 711 and is introduced into the light guide plate 712. The light incident on the light guide plate 712 propagates through the inside of the light guide plate 712, and is scattered in the direction of the prism sheet 713 on the way. As a result, the light is incident on the entire prism sheet 713 almost uniformly. The direction of these lights is adjusted by the prism sheet, enters the liquid crystal panel 714, and undergoes a predetermined attenuation to form a predetermined image.

In this embodiment, as in the case of the first embodiment, the power supplied to the lamp 710 and the signal input to the liquid crystal panel 714 correspond to the light source control / signal.
It is controlled by the video signal compensation circuit 750. As in the case of the above-described second embodiment, an optical sensor (not shown) may be provided near the lamp 710 or the light guide plate 713, and feedback may be performed while appropriately monitoring the light of the lamp. Also in the present embodiment, the circuit 7
According to 50, when the video signal corresponds to a bright signal, the power of the lamp is increased, and the light attenuation of the liquid crystal panel is increased. When the video signal corresponds to a dark screen, the lamp power is reduced. By compensating to reduce the light attenuation of the liquid crystal panel by reducing it, the contrast ratio of the displayed image can be improved while maintaining the brightness of the entire screen constant, and a clearer image than before can be obtained. .

Also, according to the present embodiment, the power consumption of the lamp can be reduced. The direct-view display device as shown in FIG. 1 is often used for various portable devices such as a notebook computer and a personal digital assistant (PDA). In these portable devices, extending the life of the built-in battery is a very important technical issue. Therefore, according to this embodiment, reducing the power consumption of the light source of the display device works very effectively.

In each of the above-described embodiments, a display panel using a liquid crystal panel has been described as a specific example. However, the present invention is not limited to this. That is, the present invention can be applied to a light source and all display devices of a type in which light from the light source is attenuated to display a predetermined image to obtain the same various effects. You can do it. For example, the present invention
The same can be applied to a display device using a mirror device as a display panel.

[0052]

The present invention is embodied in the above-described embodiment, and has the following effects.

First, according to the present invention, a clear image having a high contrast ratio can be displayed. That is, the contrast ratio of the conventional display device is about 200: 1.
In contrast, according to the present invention, the contrast ratio can be improved to about 400: 1.

In particular, according to the present invention, on a dark screen, a darker screen can be clearly displayed with a high contrast ratio, and the image quality can be remarkably improved.

Further, according to the present invention, the power consumption of the lamp can be reduced. That is, the power consumption of the lamp can be reduced to about 80% or less of the conventional power consumption. By reducing the power consumption in this manner, the power consumption of the projection display device can be reduced. Further, by using the direct-view display device according to the present invention, it is possible to extend the battery life of various portable devices such as information portable terminals.

Further, according to the present invention, by reducing the power consumption of the lamp as described above, the amount of heat generated can be reduced, and the image display device can be made smaller and lighter than before. That is, the convection space for heat radiation and the air cooling device can be simplified as compared with the related art. Further, with a decrease in the amount of heat generated, thermal deterioration of optical components such as a liquid crystal panel or an electric circuit portion is reduced, and long-term reliability can be improved. Furthermore, the life of the lamp can be extended.

According to the present invention, it is possible to provide a display device having high image quality and low power consumption, and the industrial advantage is great.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a projection display device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a light source control / video signal correction circuit 150.

FIG. 3 is a schematic diagram illustrating a configuration of a video signal correction circuit 206.

FIG. 4 is a schematic configuration diagram of a projection display device according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a configuration of a light source control / video signal correction circuit 450.

FIG. 6 is a schematic diagram illustrating a configuration of a video signal correction circuit 506.

FIG. 7 is a schematic configuration diagram of a direct-view display device according to a third embodiment of the present invention.

FIG. 8 is a schematic sectional view showing a conventional reflective liquid crystal display device.

FIG. 9 is a schematic view illustrating a pixel array of a conventional display device.

[Explanation of symbols]

 100, 400, 700, 800 Display device 110, 810 Halogen lamp 111, 811 Radiation surface reflector 112, 812 Filter 113, 115, 413, 415 Polarizer 114, 414, 714 Liquid crystal display panel 116, 416 Condenser lens 117, 417 Projection lens 118 Screen 120, 420, 720 Liquid crystal panel drive circuit 130, 430, 730 Lamp power supply 150, 750 Light source control / video signal correction circuit 151, 451, 751 Video signal input terminal 201 DC conversion circuit 202, 502 High frequency filter 203, 503 Maximum value detection circuit 204 High frequency filter 205, 505 High frequency filter 208, 508 Light source control circuit section 210 Lamp power supply 410 Metal halide lamp 411 Radiation surface reflector 412 Fill 452R, G, B sensor 461, 462, lens array 710 cold cathode tube lamp 711 reflector 712 light guide plate 713 prism sheet

Claims (12)

[Claims] 1. A light source, a display panel for attenuating and outputting light supplied from the light source, a light source power supply for supplying predetermined power to the light source in response to an input light source control signal, A display panel driving circuit that drives the display panel in accordance with a panel driving signal, and a display device that displays a predetermined image in response to a video signal input from the outside, wherein the video signal is input. And a light source control means for outputting a signal generated according to the level as the light source control signal to the light source power supply. 2. A light source, a display panel for attenuating and outputting light supplied from the light source, a light source power supply for supplying predetermined power to the light source in response to an input light source control signal, A display panel driving circuit that drives the display panel in accordance with a panel driving signal, and a display device that displays a predetermined image in response to a video signal input from the outside, wherein the video signal is input. Light source control means for outputting a signal generated according to the level to the power supply for the light source as the light source control signal, inputting the video signal and the light source control signal, and the video signal based on the light source control signal And a video signal correcting unit that corrects the above and outputs the panel driving signal to the display panel driving circuit. 3. A light source, a display panel for attenuating and outputting light supplied from the light source, a light source power supply for supplying predetermined power to the light source in accordance with an input light source control signal, A display panel driving circuit that drives the display panel in accordance with a panel driving signal, and a display device that displays a predetermined image in response to a video signal input from the outside, wherein the video signal is input. A light source control unit that outputs a signal generated according to the level to the light source power supply as the light source control signal, a sensor that monitors light output from the light source and outputs a detection signal, and the video signal. Video signal correction means for receiving the detection signal, correcting the video signal based on the detection signal, and outputting the corrected video signal as the panel drive signal to the display panel drive circuit. A display device characterized by the following. 4. The image signal includes a red image signal, a green image signal, and a blue image signal, wherein the sensor detects a red component, a sensor that detects a green component, and detects a blue component. 4. The display device according to claim 3, comprising a sensor. 5. The light source control means outputs the light source control signal to the light source power source such that the light amount of the light source increases when the level of the video signal increases. The display device according to any one of claims 2 to 4, wherein the correction is performed such that the attenuation of the display panel increases as the light amount of the light source increases. 6. A light source control means comprising: a first filter for removing a high frequency component of the video signal; a maximum value holding circuit for detecting and holding a maximum value of a signal output from the first filter; The display device according to claim 1, further comprising: a second filter configured to remove a high-frequency component of a signal output from the maximum value holding circuit. 7. The video signal includes a red video signal, a green video signal, and a blue video signal, and the maximum value holding circuit stores a maximum value of the red video signal, the green video signal, and the blue video signal. 7. The display device according to claim 6, wherein the display device is configured to detect and hold. 8. The display device according to claim 6, wherein the second filter is configured to remove a frequency component higher than a response speed of the display panel. 9. The display device according to claim 6, wherein the second filter is configured to remove a frequency component higher than a frame frequency of the video signal. 10. The display device according to claim 1, wherein the display device is a direct-view display device in which an image is directly displayed on the display panel without passing through a screen.
The display device according to any one of the above. 11. A method for displaying an image using a light source and a display panel for outputting an image by inputting and attenuating light from the light source, comprising the steps of: Detecting the maximum value of the video signal within time, controlling the light amount of the light source so that the light amount increases as the maximum value increases, and adjusting the display panel so that the attenuation increases as the maximum value increases. A display method characterized by controlling. 12. A method for displaying an image using a light source and a display panel for outputting an image by inputting and attenuating light from the light source, comprising the steps of: Detecting the maximum value of the video signal within a time period, controlling the light amount of the light source such that the light amount increases as the maximum value increases, and detecting the light amount of the light source; A display method, wherein the display panel is controlled so that attenuation is increased.