JPH08106090A - Display device - Google Patents

Abstract

PURPOSE: To provide an easy-to-see image under the environment in which a screen is set by utilizing the brightness on the screen reflecting the angular distribution of light beam incident on a modulation element as the deciding factor of the optimal value of a light converging angle. CONSTITUTION: This device has two motor-driven diaphragms (diaphragms) 104, 111. The luminous flux of a light beam incident on a condenser lens 103 is converged by the diaphragm 104 and the luminous flux of a light beam projected from a projection lens 110 is converged by the diaphragm 111. A control circuit 120 operates the diaphragms 104, 111 based on an input signal from a luminance signal smoothing circuit 140 and an input signal from a decoder 123 and controls a light beam distribution incident on a dispersion type modulation element 108 and the angular range of an exit beam contributing to the display. Namely, the brightness on the screen in the state that the modulated light beam is projected on the screen is detected and the converging angle (aperture size) of at least one of two diaphragms 104, 111 is adjusted so that the contrast and the brightness of the displayed image become an optimal value according to the brightness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying an image based on a video signal, and more particularly to a projection display device for projecting light from a light source onto a screen through a modulator.

[0002]

2. Description of the Related Art At present, a plasma light emitting panel and a modulator are attracting attention as a small and lightweight flat panel display device which replaces a CRT display device. This flat display device can be roughly classified into a self-luminous type that emits light by itself during a display operation and a transmittance control type that controls the transmittance of light incident from an independent light source during a display operation. For example, the plasma emission panel belongs to the self-emission type, and the modulation element belongs to the transmittance control type. In particular, this modulator is considered to be a favorite of the next generation display device, and its technical development is being advanced in various practical fields.

A typical modulator is a liquid crystal layer which exhibits birefringence or optical rotation of linearly polarized light using a polarizing plate, as represented by a twisted nematic type introduced in a liquid crystal device handbook. It is characterized in that it is incident on. However, such a modulation element has a drawback that the amount of light obtained from the light source is reduced to about 1/2 when passing through the polarizing plate.

Recently, a modulator which does not require the above-mentioned polarizing plate has been developed. In this modulator, a polymer dispersion type liquid crystal layer in which a liquid crystal material is contained in a polymer resin or a fine particle dispersion type liquid crystal in which fine particles are contained in a liquid crystal material is provided between a pair of transparent electrode substrates or Is transparent and the other is between the electrode substrates having a reflection characteristic, and functions as a scattering type modulation element for modulating the spatial propagation direction of the light beam incident on the liquid crystal layer. In this case, the utilization efficiency of the light from the light source is improved as compared with the device using the polarizing plate.

A modulator having a polymer dispersed liquid crystal layer is
For example, it is set to a milky white light scattering state that scatters incident light rays in the pixel area between the electrodes to which no voltage is applied, and is set to a transparent light transmission state in which the incident light rays are difficult to scatter in the pixel area between the electrodes to which voltage is applied. It For this reason,
The scattering property of each pixel region is controlled so that the intensities of the transmitted light and the reflected light are changed according to the image signal, and either the transmitted light or the reflected light is guided to the screen by the projection optical system.

The function of the modulator having the fine particle dispersed liquid crystal layer is basically the same as that of the modulator having the polymer type liquid crystal layer.

As another display device, for example, S
ID93 digest 1012 pages and beyond
Mirror Device (DMD) is introduced. The micro mirror device controls the direction of a reflected light beam by individually changing the angles of the micro mirrors arranged in a two-dimensional matrix, and the reflected light reflected in a desired direction is screened by a projection optical system. Is led to. The micro mirror device also functions in the same manner as a modulation element having a fine particle dispersion type liquid crystal layer or a polymer dispersion type liquid crystal layer in that the spatial propagation direction of incident light is modulated.

FIG. 1 schematically shows the structure of a conventional projection type display device. In FIG. 1, the light source unit 11 includes a lamp 12 which is a light source and a collimator optical system 13 which focuses light from the lamp 12 into parallel rays.
The scattering type modulation element 14 has a function of two-dimensionally modulating the spatial propagation direction of the parallel light rays incident from the collimator optical system 13, and is, for example, a polymer dispersion type modulation element. The drive circuit 20 drives the modulation element 14 according to the video signal. The projection optical system 16 includes, among the transmitted light of the modulator 14,
A diaphragm unit 15 for taking out a certain angular range is provided, and the taken-out transmitted light is screened by a screen 17.
To project. In this way, the image is displayed on the screen 17 with the light intensity distribution corresponding to the video signal.

By the way, the contrast and brightness of the display image depend on the angular distribution of the light rays used for display among the light emitted from the modulation element 14. Contrast improves as this angle distribution decreases, and brightness improves as this angle distribution increases. That is, the contrast and the brightness of the display image are in a mutually contradictory relationship.

Therefore, in JP-A-5-216004, JP-A-5-188345, etc., the diaphragm size of the diaphragm unit 15 for diaphragming the outgoing light beam emitted from the modulator 14 is made variable, and the brightness of the operating environment is increased. Disclosed is a technique for optimizing the relationship between the contrast and brightness of a display image according to the brightness.

[0011]

However, it is difficult to satisfactorily improve both the contrast and the brightness by simply changing the aperture size according to the brightness of the use environment.

It is an object of the present invention to provide a display device capable of obtaining a display image that is easier to see in accordance with the environment where the screen is placed.

Another object of the present invention is to provide a display device capable of accurately reproducing the gradation of an image.

Still another object of the present invention is to provide a display device capable of obtaining an excellent display image regardless of environmental temperature conditions.

[0015]

The present invention (Claim 1) includes:
A light source, a modulation element for optically modulating the light emitted from the light source, a liquid crystal driving means for driving the modulation element, and a light source and the modulation element are arranged between the light source and the modulation element. A first diaphragm means for limiting the light flux and having an opening whose size is variable, a display screen on which the light emitted from the modulator is projected, and a display screen for the light emitted from the modulator. A projection optical system for projecting on a projection screen, and arranged between the modulation element and the projection optical system,
Second diaphragm means having an aperture whose size is variable, which limits a light beam entering the projection optical system from the modulator, an optical sensor for detecting display brightness on the display screen, and the light. There is provided a display device comprising: an aperture control means for controlling the size of the opening of at least one of the first and second aperture means based on a display luminance signal from a sensor.

In the above display device, the following modes are possible.

The optical sensor also detects the contrast on the display screen, and the aperture control means, based on the display luminance signal and the contrast signal from the optical sensor, the first and second. 2. A display device, wherein the size of at least one aperture of the diaphragm means is controlled.

In the optical sensor, the modulation element driving means sends a white image signal to the modulation element, and the white level display brightness on the display screen where a white image is displayed and the modulation element driving means modulate By detecting a black level display brightness on the display screen in which a black image is displayed by sending a black image signal to the element, the aperture control means, the white level display brightness detected by the optical sensor and A display device, wherein the size of the opening of at least one of the first and second diaphragm means is controlled based on the contrast obtained by the ratio with the black level display luminance.

A display device characterized in that the aperture control means controls the size of the aperture of at least one of the first and second aperture means so that the contrast becomes maximum.

A display device characterized in that the aperture control means controls the converging angles of the first and second aperture means.

The aperture control means controls the size of the opening of at least one of the first and second aperture means so that the light-collecting angles of the first and second aperture means become substantially equal. And display device.

The optical sensor detects environmental brightness on the display screen based on light from the environment where the display device is placed, and based on the environmental brightness signal from the optical sensor and the display brightness signal. A display device, wherein the size of the opening of at least one of the first and second diaphragm means is controlled.

A spheroidal mirror arranged near the light source and having a focal point at the position of the light source, and a collimator optical system for making light reflected by the spheroidal mirror incident on the modulator. A display device further comprising:

A display device characterized in that the modulation element is a dispersion type liquid crystal element, a digital mirror element, or a liquid crystal diffraction element by an oblique electric field.

Further, the present invention (claim 2) includes a light source, a modulator for optically modulating the light emitted from the light source, a liquid crystal driving means for driving the modulator, the light source and the modulator. A first diaphragm unit having a variable size aperture arranged between the light source and the light source to limit the luminous flux entering the modulator, and a display screen on which the light emitted from the modulator is projected. And a projection optical system for projecting light emitted from the modulation element onto a display screen, and a light flux arranged between the modulation element and the projection optical system and incident on the projection optical system from the modulation element. Second aperture means having an aperture whose size is variable, an optical sensor for detecting display brightness on the display screen, and a video brightness signal sent from the liquid crystal drive means to the modulator. , And the optical sensor Sa - based on the display luminance signal from, provides a display device comprising a throttle control means for controlling the size of at least one opening of the first and second diaphragm means.

In the above display device, the following modes are possible.

The modulation element driving means includes a luminance signal smoothing circuit, which generates an input luminance signal indicating a temporal average intensity of the luminance signal, and the input luminance signal is supplied from the driving means. The display device is characterized in that the size of the opening of at least one of the first and second diaphragm means is controlled while correcting the drive voltage of.

In the optical sensor, the modulation element driving means sends a white image signal to the modulation element, and the white level display brightness on the display screen on which a white image is displayed and the modulation element driving means modulate the white image. By detecting a black level display brightness on the display screen on which a black image is displayed by sending a black image signal to the element, the modulation element driving means includes a brightness signal smoothing circuit. The circuit generates an input luminance signal indicating the temporal average intensity of the luminance signal, the aperture control means, the contrast obtained by the ratio of the white level display luminance and the black level display luminance detected by the optical sensor, And a display device for controlling the size of the opening of at least one of the first and second diaphragm means based on an input brightness signal from the brightness signal smoothing circuit.

The display device characterized in that the aperture control means controls the converging angles of the first and second aperture means.

The aperture control means controls the size of the opening of at least one of the first and second aperture means so that the light-collecting angles of the first and second aperture means are substantially equal. Display device to be input luminance signal indicating the temporal average intensity of the luminance signal,
A display device, which is obtained by averaging a difference between a black level signal and a luminance signal by an RC integrating circuit. The optical sensor detects the environmental brightness on the display screen based on light from the environment where the display device is placed, and the environmental brightness signal from the optical sensor, the display brightness signal, and the video brightness signal. The display device is characterized in that the size of the opening of at least one of the first and second diaphragm means is controlled based on the above.

A spheroidal mirror arranged near the light source and having a focal point at the position of the light source, and a collimator optical system for making light reflected by the spheroidal mirror incident on the modulator. A display device further comprising:

A display device characterized in that the modulation element is a dispersion type liquid crystal element, a digital mirror element, or a liquid crystal diffraction element by an oblique electric field.

A display device characterized in that the dispersion type liquid crystal element is a polymer dispersion type liquid crystal element or a fine particle dispersion type liquid crystal element.

Further, the present invention (claim 3) comprises a light source, a modulation element for optically modulating the light emitted from the light source, a liquid crystal driving means for driving the modulation element, the light source and the modulation element. A first diaphragm means which is disposed between the first light source and the light source and which limits a light beam incident on the modulation element and has an aperture whose size is variable; and a display screen on which the light emitted from the modulation element is projected. , A projection optical system that projects the light emitted from the modulation element onto a display screen, and a light flux that is disposed between the modulation element and the projection optical system and that enters the projection optical system from the modulation element. A second diaphragm means having an aperture whose size is variable, and said first diaphragm
And an aperture control means for controlling an aperture size of at least one of the second aperture means, and an aperture size of at least one aperture of the first and second aperture means controlled by the aperture control means. Provided is a display device including liquid crystal driving means for sending a video signal to the modulation element. In the above display device, the following modes are possible.

An optical sensor for detecting the display luminance on the display screen is further provided, and the aperture control means is based on the display luminance signal from the optical sensor, and the first and second apertures are provided. A display device characterized by controlling the size of at least one opening of the means.

The optical sensor also detects the contrast on the display screen, and the aperture control means, based on the display luminance signal and the contrast signal from the optical sensor, the first and the second. 2. A display device, wherein the size of at least one aperture of the diaphragm means is controlled.

In the optical sensor, the modulation element driving means sends a white image signal to the modulation element, and the white level display brightness on the display screen where a white image is displayed and the modulation element driving means modulate By detecting a black level display brightness on the display screen in which a black image is displayed by sending a black image signal to the element, the aperture control means, the white level display brightness detected by the optical sensor and A display device, wherein the size of the opening of at least one of the first and second diaphragm means is controlled based on the contrast obtained by the ratio with the black level display luminance.

The display device characterized in that the aperture control means controls the size of the aperture of at least one of the first and second aperture means so that the contrast becomes maximum.

A display device characterized in that the aperture control means controls the converging angles of the first and second aperture means.

The diaphragm control means controls the size of the opening of at least one of the first and second diaphragm means so that the light collection angles of the first and second diaphragm means are substantially equal. And display device.

The optical sensor detects environmental brightness on the display screen based on light from the environment in which the display device is placed, and based on the environmental brightness signal from the optical sensor and the display brightness signal. A display device, wherein the size of the opening of at least one of the first and second diaphragm means is controlled.

A spheroidal mirror arranged near the light source and having a focal point at the position of the light source, and a collimator optical system for making the light reflected by the spheroidal mirror incident on the modulation element. A display device further comprising:

A display device characterized in that the modulation element is a dispersion type liquid crystal element, a digital mirror element, or a liquid crystal diffraction element by an oblique electric field.

A display device characterized in that the dispersion type liquid crystal element is a polymer dispersion type liquid crystal element or a fine particle dispersion type liquid crystal element.

The present invention (claim 4) further comprises a light source,
A modulation element that optically modulates the light emitted from the light source, a liquid crystal driving unit that drives the modulation element, and a light flux that is disposed between the light source and the modulation element and that is incident on the modulation element from the light source are limited. The first diaphragm means having an aperture whose size is variable, the display screen on which the light emitted from the modulator is projected, and the light emitted from the modulator on the display screen. A second diaphragm means arranged between the projection optical system and the modulation element and the projection optical system and having a variable size aperture for limiting a light beam entering the projection optical system from the modulation element. A temperature sensor disposed in the vicinity of the modulation element, and a video signal control means for controlling a video signal sent from the driving means to the modulation element based on a temperature signal from the temperature sensor. You To provide a display device.

In the above display device, the following modes are possible.

The display device is characterized in that the modulation elements are arranged in a number corresponding to a plurality of colors.

An optical sensor for detecting the display luminance on the display screen is further provided, and the aperture control means is based on the display luminance signal from the optical sensor, and the first and second apertures are provided. A display device characterized by controlling the size of at least one opening of the means.

The optical sensor also detects the contrast on the display screen, and the aperture control means, based on the display luminance signal and the contrast signal from the optical sensor, the first and second. 2. A display device, wherein the size of at least one aperture of the diaphragm means is controlled.

In the optical sensor, the modulation element driving means sends a white image signal to the modulation element, and the white level display brightness on the display screen where a white image is displayed and the modulation element driving means modulate By detecting a black level display brightness on the display screen in which a black image is displayed by sending a black image signal to the element, the aperture control means, the white level display brightness detected by the optical sensor and A display device for controlling the size of the opening of at least one of the first and second diaphragm means based on the contrast obtained by the ratio with the black level display luminance.

The display device, wherein the aperture control means controls the size of the opening of at least one of the first and second aperture means so that the contrast becomes maximum.

The display device characterized in that the aperture control means controls the converging angles of the first and second aperture means.

The diaphragm control means controls the size of the opening of at least one of the first and second diaphragm means so that the converging angles of the first and second diaphragm means are substantially equal. And display device.

The optical sensor detects environmental brightness on the display screen based on light from the environment where the display device is placed, and based on the environmental brightness signal from the optical sensor and the display brightness signal. A display device, wherein the size of the opening of at least one of the first and second diaphragm means is controlled.

A spheroidal mirror arranged near the light source and having a focal point at the position of the light source, and a collimator optical system for making light reflected by the spheroidal mirror incident on the modulator. A display device further comprising:

The display device characterized in that the modulation element is a dispersion type liquid crystal element, a digital mirror element, or a liquid crystal diffraction element by an oblique electric field.

A display device characterized in that the dispersion type liquid crystal element is a polymer dispersion type liquid crystal element or a fine particle dispersion type liquid crystal element.

A cooling fan for cooling the modulation element is further provided, and the rotation speed of the cooling fan depends on the temperature sensor.
A display device which is controlled according to the temperature of the modulation element monitored by the display device.

Furthermore, the present invention (Claim 5) includes a light source,
A modulation element that optically modulates the light emitted from the light source, a liquid crystal driving unit that drives the modulation element, and a light flux that is disposed between the light source and the modulation element and that is incident on the modulation element from the light source are limited. The first diaphragm means having an aperture whose size is variable, the display screen on which the light emitted from the modulator is projected, and the light emitted from the modulator on the display screen. A second diaphragm means arranged between the projection optical system and the modulation element and the projection optical system and having a variable size aperture for limiting a light beam entering the projection optical system from the modulation element. An aperture control means for controlling the size of the aperture of at least one of the first and second aperture means, and an aperture size of at least one of the first and second aperture means controlled by the aperture control means. Generated correspondingly the driving voltage of the modulator element - to provide a display device including a compensating means for compensating for changes in the modulated light intensity characteristic.

In the above display device, the following modes are possible.

The compensation means corrects the video signal sent to the modulation element by the modulation element drive means in accordance with the size of the opening of at least one of the first and second diaphragm means. A display device comprising:

A display device characterized in that the drive voltage correction means increases and decreases the video signal in accordance with the decrease and increase in the size of the opening of at least one of the first and second diaphragm means, respectively.

The display device is characterized in that the modulation elements are arranged in a number corresponding to a plurality of colors.

An optical sensor for detecting the display brightness on the display screen is further provided, and the aperture control means is based on the display brightness signal from the optical sensor, and the first and second apertures are provided. A display device characterized by controlling the size of at least one opening of the means.

The optical sensor also detects the contrast on the display screen, and the aperture control means, based on the display luminance signal and the contrast signal from the optical sensor, the first and the second. 2. A display device, wherein the size of at least one aperture of the diaphragm means is controlled.

In the photosensor, the modulation element driving means sends a white image signal to the modulation element to modulate the white level display brightness on the display screen where a white image is displayed and the modulation element driving means. By detecting a black level display brightness on the display screen in which a black image is displayed by sending a black image signal to the element, the aperture control means, the white level display brightness detected by the optical sensor and A display device, wherein the size of the opening of at least one of the first and second diaphragm means is controlled based on the contrast obtained by the ratio with the black level display luminance.

The display device characterized in that the aperture control means controls the size of the opening of at least one of the first and second aperture means so that the contrast becomes maximum.

The display device characterized in that the aperture control means controls the light collection angles of the first and second aperture means.

The diaphragm control means controls the size of the opening of at least one of the first and second diaphragm means so that the converging angles of the first and second diaphragm means become substantially equal. And display device.

The optical sensor detects environmental brightness on the display screen based on light from the environment in which the display device is placed, and based on the environmental brightness signal from the optical sensor and the display brightness signal. A display device, wherein the size of the opening of at least one of the first and second diaphragm means is controlled.

A spheroidal mirror arranged near the light source and having a focus at the position of the light source, and a collimator optical system for making the light reflected by the spheroidal mirror incident on the modulator. A display device further comprising:

A display device characterized in that the modulation element is a dispersion type liquid crystal element, a digital mirror element, or a liquid crystal diffraction element by an oblique electric field.

A display device characterized in that the dispersion type liquid crystal element is a polymer dispersion type liquid crystal element or a fine particle dispersion type liquid crystal element.

The present invention (claim 6) further comprises a light source,
A modulation element that optically modulates the light emitted from the light source, a liquid crystal drive unit that drives the modulation element, and a light flux that is disposed between the light source and the modulation element and that limits the light flux that enters the modulation element from the light source. The first diaphragm means having an aperture whose size is variable, the display screen on which the light emitted from the modulator is projected, and the light emitted from the modulator on the display screen. A second diaphragm means arranged between the projection optical system and the modulation element and the projection optical system and having a variable size aperture for limiting a light beam entering the projection optical system from the modulation element. A diaphragm control means for controlling the size of the opening of at least one of the first and second diaphragm means, a light intensity setting means for setting at least two light intensities I, and the screen corresponding to these light intensities I. − An optical sensor for detecting the display luminance L of the upper - and wherein the light intensity I and the detected display luminance L L =
qI + L ₀ (L ₀ is the brightness generated on the display screen based on the light from the environment in which the display device is placed = environmental brightness) to obtain the projection coefficient q and the environmental brightness L _0.
The contrast on the display screen is obtained from the environment analysis means for obtaining the above and the above equations for the obtained projection coefficient q and the environment luminance L ₀ , and the first and second aperture means for maximizing the contrast are obtained. Means for storing data indicating the size of at least one of the openings, and the first means for maximizing the contrast in the data storage means.
And a processing unit that specifies the size of at least one opening of the second diaphragm unit and determines this size as an optimum value. In the above display device, the following modes are possible.

The light intensity setting means modulates the light intensity of the modulated light when a white image is displayed on the screen by the modulation element driving means sending a white image signal to the modulation element and the modulation element driving means. A display device characterized by setting the light intensity of modulated light when a black image is displayed on a screen by sending a black image signal to the element.

The environment analyzing means changes the size of the opening of at least one of the first and second diaphragm means at a constant ratio while the white image is displayed on the screen, and changes the size of each of the changed openings. The display brightness L _ON measured on the screen and the size of the opening of at least one of the first and second diaphragm means are changed at a constant rate while the black image is displayed on the screen. From the display brightness L _OFF on the screen measured for each changed aperture size, the ratio of L _ON and L _OFF obtained for various aperture sizes is obtained as the contrast, and this contrast is the maximum. A display device comprising a processing means for determining the size of the aperture as an optimum value.

A display device characterized in that the modulation elements are arranged in a number corresponding to a plurality of colors.

The display device characterized in that the aperture control means controls the light collection angles of the first and second aperture means.

The diaphragm control means controls the size of the opening of at least one of the first and second diaphragm means so that the converging angles of the first and second diaphragm means are substantially equal. And display device.

A spheroidal mirror arranged near the light source and having a focus at the position of the light source, and a collimator optical system for making the light reflected by the spheroidal mirror incident on the modulator. A display device further comprising:

A display device characterized in that the modulation element is a dispersion type liquid crystal element, a digital mirror element, or a liquid crystal diffraction element by an oblique electric field.

The display device as described above, wherein the dispersion type liquid crystal element is a polymer dispersion type liquid crystal element or a fine particle dispersion type liquid crystal element.

The present invention (claim 7) further comprises a light source,
A modulation element that optically modulates the light emitted from the light source, a modulation element driving unit that drives the modulation element, and a light flux that is disposed between the light source and the modulation element and that is incident on the modulation element from the light source. A first diaphragm means having an aperture whose size is variable, a display screen onto which light emitted from the modulation element is projected, and light emitted from the modulation element to a display screen. A projection optical system for projecting,
A second diaphragm unit that is arranged between the modulation element and the projection optical system and that limits a light beam that enters the projection optical system from the modulation element and that has an aperture whose size is variable; An optical path blocking means for blocking the emitted light, an optical sensor for detecting display brightness on the screen in a state where the light emitted from the modulator is blocked by the optical path blocking means, and the optical sensor And a diaphragm control means for controlling the size of the opening of at least one of the first and second diaphragm means based on the display luminance signal from the display device.

The present invention (claim 8) further comprises a light source,
A modulation element that optically modulates the light emitted from the light source, a modulation element driving unit that drives the modulation element, and a light flux that is disposed between the light source and the modulation element and that is incident on the modulation element from the light source. A first diaphragm means having an aperture whose size is variable, a display screen onto which light emitted from the modulation element is projected, and light emitted from the modulation element to a display screen. A projection optical system for projecting,
A second diaphragm unit that is disposed between the modulation element and the projection optical system and has a variable size aperture that limits a light beam that enters the projection optical system from the modulation element, and the projection optical system. Means for determining the size of the display screen by detecting the focal length of the projection lens, and obtaining the projection coefficient thereby, an optical path blocking means for blocking the light emitted from the modulator, and the modulator. An optical sensor for detecting the display brightness on the screen in a state where the light emitted from the optical path is blocked by the optical path blocking means, and the first coefficient based on the projection coefficient and the display brightness on the screen. And a diaphragm control means for controlling the size of the opening of at least one of the second diaphragm means.

[0085]

Now, various aspects of the present invention will be described with reference to the drawings.

In the display device according to the first aspect of the present invention,
The control means causes the modulator to generate modulated light under a predetermined condition in the aperture adjustment mode, detects the brightness on the screen when the modulated light is projected on the screen, and displays the brightness according to the detected brightness. The converging angle of at least one of the first and second diaphragm means, that is, the aperture size is adjusted so that the contrast and brightness of the image have optimum values. Such control of the aperture size is based on the finding found by the present inventor that the brightness and contrast of the display image largely depend on the angular distribution of the light beam incident on the modulation element.

As described above, by using the brightness on the screen, which reflects the angular distribution of the light beam incident on the modulation element, as a factor for determining the optimum value of the collection angle, the environment of the screen is set. It is possible to obtain a display image that is easier to see below. Further, even when the brightness of the room changes, the light collection angle can be automatically corrected to the optimum value in the aperture adjustment mode.

Here, in order to facilitate the understanding of the present invention, the relationship between the brightness and the contrast of the image displayed on the screen will be described.

FIG. 2 shows an example of a collimator light source for obtaining parallel rays from a lamp. The collimator light source is composed of a lamp 50, a focusing lens system 51, a diaphragm 52, and a condenser lens 53 arranged along the optical axis.

One of the characteristics of the existing lamp 50 is that it is not a point light emitter that emits light from one point. The focusing lens system 51 focuses the light emitted from the surface of the lamp 50 having a constant area as a circular lamp image 60 having a radius R at the diaphragm 52. The diaphragm 52 limits the luminous flux area of the lamp image 60 in a plane perpendicular to the optical axis. Therefore, the lamp image 60 is considered to be a surface light emitter 62 having an area determined by the radius r of the diaphragm 52. The light flux from this surface light emitter 62 enters the scattering type modulation element 54 via the condenser lens 53. However, the planar spread of the light emitting body 62 causes an angular distribution in the light beam incident on the modulation element 54.

FIG. 3 shows an incident ray of light on the condenser lens 53. The condenser lens 53 is a convex lens having a focal point at the center of the surface light emitter 62 and a sufficiently small aberration, and is used for making light rays emitted from the surface light emitter 62 parallel to each other. Here, assuming that the center of the surface light-emitting body 62 is the point a and the end of the surface light-emitting body 62 is the point b, the homologous rays traveling from the point a to the condenser lens 53 are both on the optical axis after passing through the condenser lens 53. It will be parallel. But b
After passing through the condenser lens 53, the homologous rays traveling from the point to the condenser lens 53 are all at a constant angle θ with the optical axis.
Make This angle θ is proportional to the distance between the points a and b of the lamp image 62, that is, the radius r. Condenser lens 53
Emits a luminous flux distributed at an angle of ± θ corresponding to the entire light emitting body 62 toward the modulation element. If θ is in a range that is not too large, the angular distribution Ω _i of the incident light flux that has entered the modulation element can be expressed as the solid angle by the following equation (1).

[0092]

[Equation 1] As described above, since the angle θ is proportional to the radius r of the lamp image, the angular distribution Ω _i of the incident light flux is proportional to the area of the lamp image 62. Therefore, when the intensity of the light flux that passes through the diaphragm 52 and enters the modulator is represented by I _i , the angular distribution Ω _i and the light intensity I _i correspond to the increase of the radius r of the diaphragm 52 in the range of r <R. It can be seen that it shows a monotonically increasing tendency.

Next, the display characteristics of the scattering type modulation element on which the luminous flux of the intensity I _i enters will be described. FIG. 4 shows the relationship between the angular distribution Ω _{i of the} light flux incident on the modulator and the angular distribution Ω _o of the light flux emitted from the modulator. For simplicity, it is assumed that the incident light flux is uniform in the range of the angular distribution Ωi and does not exist outside this range. Further, the modulation element uniformly scatters the incident light flux in the scattering state. This scattering capability is represented by Ω _p , which is the angular distribution Ω _o of the outgoing light flux obtained corresponding to the incident light flux having no angular distribution.

This angular distribution Ω _p is the angular distribution Ω of the incident light beam.
If it is sufficiently larger than _i , the display characteristics of the modulator have the following relationship with the light source side and projection side diaphragms.

The angular distribution Ω _i of the incident light beam shows the state of the diaphragm on the light source side, and is expressed by the following equation (2) with respect to the converging angle Ω _{A1 of the} diaphragm.

[0096]

[Equation 2] When the angular distribution Ω _o of the outgoing light flux obtained from the modulator in the non-scattering state is represented by Ω _oON , this angular distribution Ω _oON directly reflects the angular distribution Ω _i of the incident light flux as shown in the following equation (3). .

Ω _o = Ω _oON = Ω _i (3) When the angular distribution Ω _o of the outgoing light beam obtained from the modulator in the scattering state is represented by Ω _oOFF , this angular distribution Ω _oOFF is shown in FIG. Angle distribution Ω _p
It becomes a shape obtained by superimposing the angular distribution Omega _i of the incident light beam to, Omega _i
From the relationship of <Ω _p, it can be approximately set to Ω _{p as} shown in the following equation (4).

[0098]

(Equation 3) The emitted light flux described above is uniform within the range of its angular distribution Ω _o , and only the range of a fixed converging angle Ω _A2 determined by the diaphragm on the projection side is extracted and displayed. The following equations (5) and (6) represent the intensity I _o of the outgoing light flux with respect to the intensity I _i of the incoming light flux.
Shows the relationship.

I _o = (Ω _A2 / Ω _o ) · I _i (when Ω _A2 <Ω _o ) (5) In this case, the intensity I _o of the outgoing luminous flux is determined by the ratio of Ω _o and Ω _A2 .

I _o = I _i (in the case of Ω _A2 ≧ Ω _o ) (6) Contrast CR is the output light beam intensity I _ON when the modulator is in the scattering state and the output light beam intensity when it is in the non-scattering state. Obtained as the ratio of I _OFF . Generally, since Ω _A2 <Ω _p , the contrast CR becomes as shown in the following equations (7) and (8) when the magnitude relation between Ω _A2 and Ω _A1 is classified.

When Ω _A2 ≤ Ω _A1 <Ω _p CR = I _ON / I _OFF = (I _i Ω _A2 / Ω _A1 ) / (I _i Ω _A2 / Ω _p ) = Ω _p / Ω _A1 ... ( 7) When Ω _A1 ≤ Ω _A2 <Ω _p CR = I _ON / I _OFF = I _i / (I _i Ω _A2 / Ω _p ) = Ω _p / Ω _A2 (8) That is, If the larger condensing angle of the converging angle Ω _A1 and the converging angle Ω _A2 of the projection side diaphragm is represented by Ω _A ,
Contrast CR is a converging angle Ω _{A as} shown in the following equation (9).
And the angular distribution Ω _p , which indicates the scattering ability.

CR = Ω _p / Ω _A ··························································································· (9) Here, consider the relationship between the size of the converging angle Ω _A1 and Ω _A2 that determines the outgoing light flux intensity ION. . When Ω _A1 ≤ Ω _A2 , the output luminous flux intensity I _{ON for} white display is constant and does not depend on Ω _A2 from Equation (6),
From equation (9), the condition that maximizes the contrast is Ω _A1 = Ω
It is _A2 . When Ω _A1 ≧ Ω _A2, the contrast is CR = Ω _p / Ω _A1 from the formula (7), and I _ON = I _i from the formula (5).
Ω _A2 / Ω _A1 . Therefore, when Ω _A2 = Ω _A1 (= Ω _i ), the output luminous flux intensity I _ON becomes maximum. From both of them, the condition that the intensity of the emitted light beam is strongest with respect to an arbitrary contrast and the condition that the contrast is highest with respect to an arbitrary brightness is Ω _A1 = Ω _A2 . As described above, the condition that it is to improve the most display characteristics converging angle Omega _A2 with converging angle Omega _A1 of the light source side throttle projection side throttle match.

Even when considered under the above optimum conditions, the brightness of the display image, that is, the output luminous flux intensity I _ON (= I _i ) improves with an increase in the radius r of the diaphragm, but the contrast CR of the display image. It can be seen that, along with this, decreases. That is, by adjusting the size of the diaphragm, I _ON
It can be seen that changing CR and CR cannot both improve them.

The above is a qualitative consideration, and more detailed consideration needs to be made individually depending on the optical system method, lamp characteristics, etc., but the basic idea is that the brightness and contrast of the displayed image are traded off. The behavior is as follows: polymer dispersion type, fine particle dispersion type, liquid crystal diffraction grating by oblique electric field (Japanese Patent Application No. 6-298496, Japanese Patent Application No. 6-172935).
No.), or a modulation element such as DMD that modulates the spatial propagation direction of light.

Here, the contrast of the image displayed on the screen by the operation of the projection type display device using the polymer dispersed liquid crystal as the scattering type modulation element will be considered. The contrast of the displayed image is affected by the environment surrounding the screen. Therefore, an image was displayed on a screen placed in an illuminated room, and the intensity of the luminous flux emitted from the modulation element and the contrast of the image were measured corresponding to the converging angle of the diaphragm. FIG. 5 shows the intensity of the light beam emitted from the modulation element and the contrast of the image, which are measured in accordance with the light collection angle. From this relationship, it can be seen that the optimum value that produces the maximum contrast exists within the adjustment range of the collection angle.

When an image is displayed on the screen by the operation of the display device, the brightness L of the screen depends on the brightness L _ON or L _OFF of the display image and the background brightness L ₀ depending on the environment in which the screen is placed. Will be the sum of Therefore, the actual contrast CR _room is represented by the following expression (10) using the brightnesses L _ON and L _OFF .

CR _room = (L _ON + L ₀ ) / (L _OFF + L ₀ ) ..... (10) The background brightness L ₀ is the illumination light of the room where the screen is placed and the external light taken from the window. Is a value obtained by multiplying the strength of the like by one of the light transmittance and the light reflectance determined by the display format (light transmission type, light reflection type) of this screen. This L ₀ is
It cannot be ignored because it has the effect of significantly lowering the original contrast CR obtained from equation (9).

When the value of L ₀ is sufficiently small, the contrast exhibits a dependency of 1 / Ω _A, which is close to the original inclination, and the smaller the collection angle Ω _{A, the} better the contrast. Conversely, L ₀
When the value of is sufficiently large, the maximum brightness is dominant in the contrast ratio, and the larger the collection angle Ω _A , the larger the contrast.

Therefore, when L ₀ is an intermediate value, the contrast CR _room obtained corresponding to the diaphragm focusing angle Ω _A
Consider. The relationship between the converging angle Ω _{A of} the diaphragm, the intensity I of the light projected from the display device, and the brightness L of the screen can be expressed by the following equation (11) by using the positive proportional coefficients k and q. it can.

L = kΩ _A = qI (11) The following equation (12) shows the actual contrast CR _room in consideration of the background brightness L ₀ .

CR _room = (L _ON + L ₀ ) / (L _OFF + L ₀ ) = (Ω _A + L ₀ / k) / (Ω A ₂ / Ω _P + L ₀ / k) (12) When L ₀ = 0 As mentioned above, the smaller the collection angle Ω _{A, the} better the contrast. The following expression (13) shows a necessary condition for maximizing the contrast when L ₀ is a finite value larger than 0.

[0112]

[Equation 4] If there is a point of maximum contrast, it will be shaped depending on the background brightness L ₀ and the collection angle Ω _A of the diaphragm. When the converging angle Ω _A has a feasible solution in Expression (13), this solution has an optimum value that maximizes the contrast CR _room . However, the upper limit of the focusing angle Ω _A of the diaphragm is substantially determined by the size of the actual light source. That is, there is an upper limit value of the adjustable range. Therefore, when L ₀ exceeds a certain fixed value, the setting that maximizes Ω _A within the adjustment range is the optimum value so that the contrast becomes maximum within the adjustment range.

When L _{0 has} a value of almost 0, the smaller the collection angle Ω _{A, the} better the contrast. But,
If the converging angle Ω _A is actually made too small, the displayed image becomes dark and difficult to see. In such a case, the light collection angle Ω _A is minimized within a range where the displayed image is easy to see.

[0114]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The projection type display device according to various aspects of the present invention will be described below, but before the description, the basic concept of the present invention will be described.

FIG. 6 shows the structure of a projection type display device for explaining the basic concept of the present invention. Regarding the optical system, the projection display device includes a spheroidal mirror 101 and a light source lamp 1.
02, a condenser lens 103, an electric diaphragm 104, a scattering type modulation element 108, a field lens 109, a projection lens 110, and an electric diaphragm 111. Lamp 10
The light obtained from 2 is reflected by the mirror 101 directly and enters the condenser lens 103. The condenser lens 103 converts the incident light into parallel rays and scatter-type modulator 1
08. The scattering type modulation element 108 includes a polymer dispersion type liquid crystal layer in which a liquid crystal material is dispersed in a polymer resin as a light modulation layer between a pair of transparent electrode substrates, and the light modulation layer spatially propagates light. It is driven by the drive circuit 107 as a modulation element that modulates the direction according to the video signal. The modulated light from the scattering type modulation element 108 enters the projection lens 110 via the field lens 109. The projection lens 110 projects the incident light on the reflective screen SC. That is, the basic display principle of this projection type display device is the same as the conventional one.

The feature of this display device is that it has two electric diaphragms 1.
04 and 111. The diaphragm 104 is provided for narrowing the luminous flux of the light rays incident on the condenser lens 103, and the electric diaphragm 111 is provided for narrowing the luminous flux of the light rays projected from the projection lens 110. Each electric diaphragm has a built-in servomotor controlled by the control circuit 120, and the operation of this servomotor adjusts the diaphragm size, that is, the shape of the opening. The control circuit 120 operates the diaphragms 104 and 111 on the basis of the input signal A from the luminance signal smoothing circuit 140 and the input signal B from the decoder 121, and the luminous flux distribution incident on the scattering type modulation element 108 and the emission which contributes to the display. Controls the luminous flux angle range. The decoder 121 receives the control signal transmitted from the external infrared remote controller and decodes it to obtain the signal B.

FIG. 13 shows the relationship between the input signals A and B of the control circuit 120 and the converging angle of the diaphragm. The state of the diaphragm is shown as an angle at which the light flux emitted from the scattering modulator 108 passes through the diaphragm, that is, as a converging angle. The converging angle of the diaphragm 111 is set so as to be variable in the range of 8.6 × 10 −3 sr to 1.1 × 10 −3 sr. The diaphragm 104 is also controlled so that the light flux in the same angle range is incident on the scattering type modulation element 108.

The input signal A of the control circuit 120 is the temporal average intensity of the luminance signal included in the video signal and is generated by the luminance signal smoothing circuit 140. The luminance signal smoothing circuit 140 is composed of a luminance signal blanking level (black level) detection circuit 140A and an RC integration circuit 140B as shown in FIG. The time constant RC of the integrating circuit 140B can be changed by adjusting the resistance R.
The input signal A of the control circuit 120 is obtained by averaging the difference between the output (black level) of the blanking level (black level) detection circuit 140A and the luminance signal by the RC integration circuit 140B. The input signal B of the control circuit 120 is a signal obtained by decoding the control signal from the infrared remote controller by the decoder 121, and this signal can be set to an arbitrary value by the infrared remote controller. This signal changes the strength of the influence of the input signal A on the diaphragm, as shown in FIG. When the value of the input signal B is made sufficiently small, the diaphragm becomes constant regardless of the input signal A in the state where the converging angle is minimum. On the contrary, when the value of the input signal B is made sufficiently large, the diaphragm becomes constant regardless of the input signal A in the state where the converging angle is maximum. When the light collection angle is fixed at a specific value, the changeover switch (not shown) provided in the control circuit 120 sets the input signal A to be constant at an intermediate signal fixed value shown in FIG.

The drive circuit 107 is characterized in that the output signal of the smoothing circuit 140B is used as one of the inputs to correct the voltage for driving the scattering type liquid crystal panel. In this correction, the operating state of the control circuit 120 is detected from the decoded signal from the decoder 121, and the change in the average intensity of the drive signal is corrected in synchronization with the control circuit so as to decrease. Therefore, when the originally dark projected image becomes darker due to the smaller converging angle, the brightness of the scattering type liquid crystal panel is corrected to the opposite direction, and the fluctuation of the brightness in the finally obtained projected image is corrected. Is alleviated.

When the display device having the above-described structure was operated for display in a dark room, it was observed that when the contrast ratio was 1.1 × 10 −3 sr due to insufficient characteristics of the polymer dispersed liquid crystal,
In the case of 0: 1 and 8.6 × 10 −3 sr, the contrast ratio was 18: 1. Also, the amount of light during white display is 18 lm when the collection angle is 1.1 × 10 −3 sr, which is 8.6 ×
The display was 75 lm at 10 -3 sr. When the diaphragm is fixed, in order to obtain a sufficient contrast ratio, it is necessary to use the diaphragm in the condition of 1.1 × 10 −3 sr where the light collection angle becomes the minimum. On the other hand, in the case of being variable as in the embodiment, the overall brightness can be increased in a bright scene, and thus the display impression is dramatically improved. In particular, when the display operation is performed using video software that records images of constellations and the world of the moon, the background black is tightened in the constellation scene,
The display is very good, which is completely different from when the aperture is fixed. Regarding the relationship between the average brightness change and the aperture adjustment speed, the aperture adjustment time constant was set from 0.5 seconds to 1 second, and the display characteristics were improved without feeling any unnaturalness. did it.

Next, when a screen having a reflection gain of 13 times was used for display in a room of 500 lux, the brightness of the screen due to the room light was considerably annoying, and the converging angle was almost maximum. The best impression was obtained when set to. This setting is a bad setting compared to the case where the converging angle is made smaller, because the lack of contrast becomes more of a concern when the room is sufficiently dark. It was confirmed that when the display device of this example was used, the display operation could be performed by optimizing the display characteristics even if the brightness of the usage environment was different.

In a bright environment, the human sense recognizes a dark portion as black for its brightness, and therefore, in a bright scene, the requirement for black display is not so strict. In this case, it is important that the white part is sufficiently bright rather than the contrast ratio.

On the contrary, in a dark scene, the sense is sensitive to darkness so that the distinction between light black and dark black becomes clear. The brightness of the white part is emphasized by comparison with the surrounding black part, so the absolute brightness of the white part is not so important. In this case, it is required that the contrast ratio be good and that black be displayed sufficiently dark.

This projection type display device can change the display characteristic so as to satisfy the human sense, and can also obtain the display characteristic which has not been obtained in the past. That is, the substantial brightness can be improved under a sufficient contrast ratio.

This projection type display device is actually used in various environments depending on the time zone or place. In particular, since the outside light (indoor lighting, the lighting portion of the window) acts on the screen to determine its brightness, the black image portion is very susceptible. That is, if the periphery of the screen is too bright, the contrast of the image displayed on the screen is lowered even if the output light from the display device has a good contrast ratio. Therefore, in such a state, the display in which the brightness is prioritized over the contrast ratio is performed. Also,
In a sufficiently dark room or the like, even if the white display is a little dark, the display is made so that the black looks solid.

In this projection type display device, it is possible to arbitrarily select whether to give priority to black display or white display depending on various conditions of the surrounding environment. Further, this display device has low power consumption despite having the above-mentioned good display performance.

In the above example, the reflective screen SC is used for viewing the display image on the front side, but the transmissive screen may be used for viewing the display image on the rear side.

Further, in this example, the display device is configured to utilize the transmitted light of the scattering type liquid crystal panel provided as the modulation element, but it may be configured to utilize the reflected light of the scattering type liquid crystal panel. Good. This scattering type liquid crystal panel may have, for example, a fine particle dispersion type liquid crystal layer as a light modulation layer instead of the polymer dispersion type liquid crystal layer. Further, the scattering type liquid crystal panel may be changed to a DMD, a TN type liquid crystal or a modulation element such as a liquid crystal diffraction grating by an oblique electric field.

The projection type display device according to the first aspect of the present invention will be described below with reference to FIG.

In FIG. 7, the projection type display device includes a spheroidal mirror 101, a light source lamp 102, and an electric diaphragm 10.
4, condenser lens 103, scattering type modulation element 108,
The optical system includes a field lens 109, a projection lens group 110, and an electric diaphragm 111 arranged on the optical axis. The light obtained from the lamp 102 is reflected by the mirror 101 directly and enters the condenser lens 103. The condenser lens 103 makes this incident light incident on the modulation element 108 as parallel light rays. The modulator 108 modulates the spatial propagation direction of incident light in a two-dimensional area and is driven by the modulator driver circuit 107. The modulation element 108 is a liquid crystal panel having a liquid crystal layer in which a liquid crystal material is dispersed in a polymer resin, between a pair of transparent electrode substrates. The field lens 109 is the modulation element 108
The modulated light from is guided to the projection lens group 110, and the projection lens group 110 projects this modulated light on the reflection type screen SC. That is, the basic display principle of this projection type display device is the same as the conventional one.

In this display device, the electric diaphragm 104 is arranged between the light source lamp 102 and the condenser lens 103, and the electric diaphragm 111 is arranged in the projection lens group 110. The motorized diaphragm 104 restricts the luminous flux of the light source light from the light source lamp 102 in order to control the angular range of the light rays incident on the modulation element 108, and the motorized diaphragm 111 modulates to control the angular range of the light rays projected on the screen SC. Element 108
The modulated light flux from is narrowed.

The electric diaphragms 104 and 111 have a built-in servomotor M controlled by the diaphragm drive circuit 123, and the diaphragm size, that is, the shape and size of the opening is adjusted by the operation of this servomotor. The shape of the opening may be a quadrangle, a circle, or the like, and particularly preferably a circle as shown in FIG. 8A and a structure in which the radius r is changed by a servo motor. Further, as shown in FIG. 8B, a structure may be employed in which the upper and lower sides and / or the left and right sides of the opening are shielded by a servo motor. It is more preferable to shield the top / bottom / left / right to form a square opening.

Particularly preferably, the motorized diaphragms 104 and 1
As shown in FIGS. 8 (c) to 8 (e), it is preferable that 11 has the same configuration as an aperture often used in cameras. 8C shows the case where the opening diameter is small, FIG. 8D shows the case where the opening diameter is intermediate, and FIG. 8E shows the case where the opening diameter is large.

In the example shown in FIG. 7, each of the electric diaphragms 104 and 111 is composed of five ceramic blades CB having excellent heat resistance. By changing the size of the circular opening formed by the combination of these ceramic blades CB, that is, the radius r by the servomotor M, the electric diaphragms 104 and 111 function as a circular variable diaphragm whose converging angle changes.

Further, this display device has a display control circuit 121 for controlling the entire display operation, and this display control circuit 121.
Each of the motorized diaphragms 104 and 111 is driven so as to have a raster signal generation circuit 122 for generating a raster signal set to a brightness level specified by the display control circuit 121 and a converging angle specified by the display control circuit 121, that is, an aperture radius r. The aperture drive circuit 123, the optical sensor 128 that detects the brightness of the screen SC and generates an analog voltage signal according to the brightness, and the voltage signal from the optical sensor 128 is converted into a digital signal and displayed in the display control circuit 121. It has an optical sensor interface circuit 124 for input.

The display control circuit 121 has a data bus 125.
Raster signal generation circuit 122 and diaphragm drive circuit 1 via
23 and the optical sensor interface circuit 124, the optical sensor 128 is connected to the optical sensor interface circuit 124, and the diaphragm drive circuit 123 is connected to the electric diaphragm 1.
The modulator driving circuit 1 is connected to the 04 and 111 diaphragms.
07 is connected to the modulation element 108.

This display device has a raster signal generating circuit 1
Changeover switches SW1 and SW3 controlled by the state of No. 22, and a push switch SW2 for commanding aperture adjustment.
Have and. The switch SW1 is a first contact point connected to the video input terminal 131 to which the video signal is supplied, and a second contact point connected to the raster signal output terminal of the raster signal generating circuit 122.
A contact, a common contact connected to the modulation element drive circuit 107,
And a control terminal connected to the status output terminal of the raster signal generation circuit 122.

The switch SW2 is connected between a pair of switch connection terminals of the display control circuit 121. Switch SW
3 is a first contact connected to one end of the variable resistance 127, a second contact connected to one end of the fixed resistance 126, a common contact connected to one of the resistance connection terminals of the diaphragm drive circuit 123,
And a control terminal connected to the status output terminal of the raster signal generation circuit 122. The other ends of the fixed resistance 126 and the variable resistance 127 are connected to the other of the resistance connection terminals of the diaphragm drive circuit 123.

The display control circuit 121 detects that the switch SW2 has been pressed and sets the aperture adjustment mode. The raster signal generating circuit 122 is normally maintained in a stopped state and is activated in this diaphragm adjustment mode. The switch SW1 connects the common contact to the first contact under the status signal supplied when the raster signal generating circuit 122 is in the stopped state, and the status supplied when the raster signal generating circuit 122 is in the operating state. The common contact is connected to the second contact under the signal.

That is, normally, the switch SW1 supplies the video signal to the modulation element drive circuit 107, and the switch SW3.
Connects the variable resistor 127 to the diaphragm drive circuit 123. When the raster signal generation circuit 122 is activated due to the aperture adjustment mode setting, the switch SW1 supplies the raster signal to the modulation element drive circuit 107, and the switch SW2.
Connects the fixed resistor 126 to the diaphragm drive circuit 123.

The diaphragm driving circuit 123 adjusts the electric diaphragms 104 and 111 to the converging angle of the electric diaphragm, that is, the opening radius designated by the display control circuit 121, in a state of being connected to the fixed resistor 126. The variable resistor 127 is provided to further correct the light collection angle thus set, and is manually operated. Aperture drive circuit 123
Is the variable resistor 1 when connected to the variable resistor 127.
When 27 is operated, the value of the light collection angle is corrected in the positive and negative directions according to the resistance value of the variable resistor 127. The light sensor 128 is composed of, for example, a photodiode and a condenser lens, and the brightness of the screen SC is controlled by the display control circuit 1 from the light sensor 128 via the light sensor interface 124.
It is measured based on the signal supplied to 21.

The display control circuit 121 has a microprocessor MP for performing various data processing, and a memory SM for storing a control program for the microprocessor MP and various data. The control program includes a processing routine for determining the optimum light collection angle in the aperture control mode.

Next, the operation of this display device will be described with reference to the flowcharts shown in FIGS.

In FIG. 9, the display control circuit 121 performs a display control process by executing a control program when the power is turned on. When this display control process is started,
In step S201, it is checked whether the push switch SW2 has been pressed. When it is detected that the push switch SW2 has been pressed, the display control circuit 121 sets the aperture adjustment mode and sets the brightness level of the raster signal to the maximum in order to activate the raster signal generator 122 in step S202. Raster signal generator 1
Specify 22.

The switch SW1 is the raster signal generator 1
The raster signal generated from the modulator 22 is applied to the modulator driving circuit 1
07, and the switch SW3 connects the fixed resistor 126 to the diaphragm drive circuit 123. At this time, the modulation element drive circuit 107 responds to the raster signal by the light transmittance (modulation degree).
The modulation element 108 is driven so as to maximize the light emission, and the brightest modulated light for displaying a white image on the entire screen SC is emitted. After that, the display control circuit 121 determines in step S2.
At 03, a measurement process for obtaining the brightness of the screen SC for various converging angles of the diaphragm is performed.

FIG. 10 shows this measurement process in more detail. The display control circuit 121 is determined in consideration of the response time required to actually drive the modulator 108.
Waiting for a predetermined time of about 2 seconds to elapse in step S251, and in step S252, the converging angle of 1.0 × 10 ⁻³ srad is set in order to set each diaphragm to the most narrowed state.
Specify 23. The display control circuit 121 measures the screen brightness detected by the optical sensor 128 in a state in which each diaphragm is most narrowed in step S254. After that, the display control circuit 121 sets the converging angle to 0.5 in step S253.
The brightness of the screen detected by the optical sensor 128 is measured at step S254 every time the converging angle is increased by increasing at a rate of × 10 ^-3 srad. When it is detected in step S255 that the converging angle reaches 9.5 × 10 ⁻³ srad, which is the value for opening the diaphragm to the maximum open state, the measurement process for displaying a white image ends, and Step S20 shown in
4 is executed.

In step S204, the display control circuit 121 instructs the raster signal generator 122 to minimize the luminance level of the raster signal in step S202. The switches SW1 and SW2 function as in step S202. At this time, the modulation element drive circuit 1
Reference numeral 07 drives the modulation element 108 so as to minimize the light transmittance (modulation degree) corresponding to the raster signal, and the screen SC
The darkest modulated light for displaying a black image on the whole is emitted. After that, the display control circuit 121 determines in step S205.
Then, the measurement process shown in FIG. 10 is performed again. When the measurement process for displaying the black image is completed, step S206 is executed.

In step S206, the display control circuit 121 creates a data table showing the relationship between the light collection angle and the contrast. This data table is created by obtaining as a contrast the ratio of the brightness measurement value obtained in step S203 and the brightness measurement value obtained in step S205 for the same converging angle. In step S207, the display control circuit 121 searches the data table for the optimum converging angle that maximizes the contrast, and specifies the optimum converging angle to the diaphragm drive circuit 123. When the diaphragm drive circuit 123 drives each of the motorized diaphragms 104 and 111 so as to have the optimum converging angle, the display control circuit 121 releases the diaphragm adjustment mode in order to bring the raster signal generator 122 into the stopped state, and the step is restarted. S
Execute 201. After canceling the aperture adjustment mode, the switch SW1 supplies the video signal input to the video input terminal to the modulation element drive circuit 107, and the switch SW3 sets the variable resistor 1
27 is connected to the diaphragm drive circuit 123.

In the above-described embodiment, by pressing the switch SW2, the optimum converging angle of the diaphragm that maximizes the contrast is obtained, and the diaphragm is automatically adjusted to have this optimum converging angle. Since the variable resistor 127 becomes available after this adjustment, the brightness of the display image obtained under the optimum collection angle can be changed to be brighter or darker according to preference.

Here, the result of the display experiment obtained with the modulator using the polymer-dispersed liquid crystal will be shown. The contrast is 70: 1 when the collection angle is 1.0 × 10 ⁻³ srad, and the collection angle is 9.
In the case of 5 × 10 ⁻³ srad, the ratio was 18: 1. The amount of light when displaying a white image is 18 lm when the collection angle is 1.0 × 10 ^-3 srad, and 75 l when the collection angle is 9.5 × 10 ^-3 srad.
The display was m. In addition, the display experiment was performed while changing the brightness of the room. Since the switch SW2 is pressed each time, the converging angles of the electric diaphragms 104 and 111 are quickly adjusted to the optimum value that maximizes the contrast. It is possible to easily deal with such changes in the usage environment.

Next, an example of another projection type display device according to the first aspect of the present invention will be described with reference to FIG.

This display device is composed of exactly the same hardware as the device shown in FIG. 7 except the contents of the memory SM provided in the display control circuit 121. Therefore, the same parts are designated by the same reference numerals, and the description of the hardware parts is omitted. In this embodiment, the motorized diaphragms 104 and 111
Data showing a standard relationship between various converging angles in a variable range common to all, and the modulated light intensity emitted from the modulator for displaying a white image and a black image under these converging angles, respectively. The table is stored beforehand in the memory SM and the control program is modified to use this table.

That is, the display control circuit 121 executes the control program when the power is turned on, and
The display control process shown in 1 is performed. When this display control process is started, it is first checked in step S301 whether the push switch SW2 has been pressed. When it is detected that the push switch SW2 is pressed, the display control circuit 121 sets the aperture adjustment mode to activate the raster signal generator 122 in step S302, and the standard of 2.1 × 10 ⁻³ srad is set. The converging angle of the stop is designated to the stop drive circuit 123, and step S303 is performed.
The raster signal generator 122 is designated to maximize the brightness level of the raster signal.

The switch SW1 supplies the raster signal generated from the raster signal generator 122 to the modulation element drive circuit 107, and the switch SW3 connects the fixed resistor 126 to the diaphragm drive circuit 123. At this time, the modulation element drive circuit 107 drives the modulation element 108 so as to maximize the light transmittance (modulation degree) corresponding to the raster signal, and emits the brightest modulated light for displaying a white image on the entire screen SC. . After that, the display control circuit 121 waits in step S304 until a predetermined time of about 0.5 seconds, which is determined in consideration of the response time required to actually drive the modulation element 108, elapses, and then the light is condensed by the diaphragm. The corner is 2.1 × 10 _-3
The brightness detected by the optical sensor 128 in the state of being set to srad is measured in step S305.

Further, the display control circuit 121 instructs the raster signal generator 122 to minimize the luminance level of the raster signal in step S306. Switch SW
1 and SW3 function as in step S303. At this time, the modulation element drive circuit 107 drives the modulation element 108 so as to minimize the light transmittance (modulation degree) in response to the raster signal, and emits the darkest modulated light for displaying a black image on the entire screen SC. .

After that, the display control circuit 121 waits for a predetermined time of about 0.5 seconds, which is determined in consideration of the response time required to actually drive the modulation element 108, in step S307, and then the aperture is stopped. Opening angle is 2.1 × 10 ^-3
The brightness detected by the optical sensor 128 in the state of being set to srad is measured in step S308.

The display control circuit 121 determines in step S309.
Then, an expression L _ON that represents the relationship between the brightness L _ON obtained when a white image is displayed on the screen, the intensity I _{ON of the} modulated light emitted from the modulation element 108, and the background brightness L _0.
= QI _ON + L ₀ , and the brightness L _OFF obtained when a black image is displayed on the screen, and the modulation element 10
8 and the intensity I _OFF of the modulated light emitted from the obtained equation L _OFF = qI _OFF + L lightness L ₀ of the projection coefficients q and background is included in ₀ representing the relationship between the brightness L ₀ of the background. That is, the measured values of L _ON and L _OFF obtained in steps S305 and S308 are substituted into these equations together with the intensities I _ON and I _{OFF of the} modulated light. Here, q is a positive constant, and I _ON and I _OFF are values obtained from the data table stored in the memory SM.

After that, in step S310, the display control circuit 121 sets q and L _0, which have become known in step S309, to two values L _ON = qI _ON + L ₀ and L _OFF = qI _OFF + L ₀ shown in step S309. Substituting into the expression,
Further, the intensity I _{ON of the} modulated light obtained from the data table assuming that the converging angle is changed in the variable range common to the diaphragm.
By substituting I _OFF and I _OFF into these equations, a converging angle that maximizes the contrast L _ON / L _OFF is obtained, and this converging angle is designated to the diaphragm drive circuit 123 in step S311.

When the diaphragm driving circuit 123 drives each of the motorized diaphragms 104 and 111 so as to have this converging angle, the display control circuit 121 releases the diaphragm adjustment mode in order to stop the raster signal generator 122 in step S312. Then, step S301 is executed again. After canceling the aperture adjustment mode, the switch SW1 supplies the video signal input to the video input terminal to the modulation element drive circuit 107, and the switch SW3 connects the variable resistor 127 to the aperture drive circuit 123.

In the second embodiment, as in the first embodiment, by pressing the switch SW2, the optimum converging angle of the diaphragm that maximizes the contrast is obtained, and the diaphragm determines this optimum converging angle. Automatically adjusted to have. Since the variable resistor 127 becomes available after this adjustment, the brightness of the display image obtained under the optimum collection angle can be changed to be brighter or darker according to preference.

Further, in this embodiment, the light collecting angle of the diaphragm can be optimized in a short time. That is, in the first embodiment, with the white image and the black image displayed on the screen, the converging angle of the diaphragm is changed at a rate of 0.5 × 10 ⁻³ srad in the variable range, and the screen is changed each time. You have to measure the brightness of. On the other hand, in the second embodiment, the number of times the brightness of the screen is measured can be reduced to two times by using the data table prepared in the memory SM, and as a result, the converging angle of the diaphragm is optimized. It is possible to reduce the time required to do so to 5 seconds or less.

Further, in this second embodiment, the expression L
To estimate the q and L ₀ in = q I + L _0,
Brightest light intensity I _ON obtained at a standard collection angle
The brightness L was measured by using the modulated light of No. 1 and the modulated light of the darkest light intensity I _OFF as the emitted lights, respectively, but the use of other modulation states does not impair the gist of the present invention.

For example, the light intensity I _{AMAX of the} modulated light obtained when the converging angle is maximized and the converging angle is minimized at the modulation degree of the modulation element set to a predetermined halftone level. The light intensity I _AMIN of the modulated light and the brightness L _AMAX measured by using these modulated lights as emitted light, respectively.
And L _AMIN by substituting
You may ask for ₀ .

L _AMAX = qI _AMAX + L ₀ L _AMIN = qI _AMIN + L _{0 The} point is that at least two modulated lights of different light intensities are projected onto the screen SC in order to obtain q and L ₀ , and at this time, The purpose is to measure the brightness of the screen SC. However, the accuracy of q and L ₀ improves as the intensity difference between these modulated lights increases, so it is preferable to set the intensity of one modulated light to the maximum and minimize the intensity of the other modulated light.

Further, instead of projecting two modulated lights of different intensities, for example, three or more n different modulated lights can be projected. The brightness obtained by projecting these modulated lights is expressed by the following equation.

L _i = q I _i + L ₀ (i = 1,2, ... N) In this case, q and L ₀ may be obtained using a method such as the least square method. If these q and L ₀ are obtained, the optimal aperture state corresponding to the obtained ratio of q and L _{0 is} determined from the one-dimensional data table showing the relation of the optimal aperture state with respect to various ratios q / L ₀ . You can decide.

In each of the above-described embodiments, the reflective screen SC is used to see the display image on the front side, but the transmissive screen may be used to see the display image on the rear side. Good.

Further, in each of the embodiments, the display device is configured to use the transmitted light of the modulator as the modulated light, but it may be configured to utilize the reflected light of the modulator. Further, the modulation element may use, for example, a fine particle dispersion type liquid crystal or DMD, a liquid crystal diffraction grating by an oblique electric field, etc. instead of the polymer dispersion type liquid crystal.

As described above, according to the first aspect of the present invention, the brightness of the screen reflecting the angular distribution of the light beam incident on the modulation element is detected, and this value maximizes the contrast of the displayed image. Since it is used for adjusting the aperture, it is possible to obtain a display image that is easier to see under the environment where the screen is placed.

Next, a projection type display device according to the second aspect of the present invention will be described.

FIG. 12 shows the structure of this projection type display device. Regarding the optical system, the projection display device includes a spheroidal mirror 101, a light source lamp 102, and a condenser lens 10.
3, an electric diaphragm 104, a modulator 108, a field lens 109, a projection lens 110, and an electric diaphragm 111. The light obtained from the lamp 102 is reflected by the mirror 101 directly and enters the condenser lens 103. The condenser lens 103 causes the incident light to enter the modulation element 108 as parallel rays. The modulation element 108 is
A polymer-dispersed liquid crystal layer formed by dispersing a liquid crystal material in a polymer resin is provided between a pair of transparent electrode substrates as a light modulation layer,
The light modulation layer drives the driving circuit 107 as a modulation element that modulates the spatial propagation direction of light according to a video signal. The modulated light from the modulation element 108 enters the projection lens 110 via the field lens 109. The projection lens 110 projects the incident light on the reflective screen SC. That is, the basic configuration of this projection display device is
This is the same as the projection type display device shown in FIG. 7.

This display device is similar to the device shown in FIG.
It has two motorized apertures 104 and 111. The diaphragm 104 is provided for narrowing the luminous flux of the light rays incident on the condenser lens 103, and the electric diaphragm 111 is provided for narrowing the luminous flux of the light rays projected from the projection lens 110. The control circuit 120 for each motorized diaphragm controls the diaphragms 104 and 111 based on the input signal A from the luminance signal smoothing circuit 140, the input signal B from the decoder 129, and the signal C from the photosensor interface circuit 124. Let it work,
It controls the distribution of the luminous flux that enters the modulator 108 and the angular range of the outgoing luminous flux that contributes to the display. The decoder 129 receives a control signal transmitted from an external infrared remote controller,
A signal B is obtained by decoding this.

FIG. 13 shows the relationship between the input signals A and B of the control circuit 120 and the converging angle of the diaphragm. The state of the diaphragm is shown as an angle at which the light flux emitted from the modulation element 108 passes through the diaphragm, that is, a converging angle. The converging angle of the diaphragm 111 is
It is set so as to be variable in the range of 8.6 × 10 ⁻³ sr to 1.1 × 10 ⁻³ sr. Further, the diaphragm 104 is also controlled so that the light flux in the same angle range is incident on the modulation element 108.

The input signal A of the control circuit 120 is the temporal average intensity of the luminance signal included in the video signal, and is generated by the luminance signal smoothing circuit 140. As shown in FIG. 10, the brightness signal smoothing circuit 140 includes brightness signal blanking level (black level) detection circuits 140A and R.
It is composed of a C integration circuit 140B. Integrating circuit 140
The time constant RC of B can be changed by adjusting the resistance R. The input signal A of the control circuit 120 is obtained by averaging the difference between the output (black level) of the blanking level (black level) detection circuit 140A and the luminance signal by the RC integration circuit 140B.

The input signal B of the control circuit 120 is a signal obtained by decoding the control signal from the infrared remote controller by the decoder 129, and this signal can be set to an arbitrary value by the infrared remote controller. As shown in FIG. 12, this signal changes the strength of the influence of the input signal A on the diaphragm. When the value of the input signal B is made sufficiently small, the diaphragm is in a state where the converging angle is minimum. It is constant regardless of the input signal A. On the contrary, when the value of the input signal B is made sufficiently large, the diaphragm becomes constant regardless of the input signal A in the state where the converging angle is maximum. Further, when the light collection angle is fixed to a specific value, the changeover switch (not shown) provided in the control circuit 120 sets the input signal A to be constant at an intermediate signal fixed value shown in FIG.

The driving circuit 107 is characterized in that the output signal of the smoothing circuit 140B is used as one of the inputs to correct the voltage for driving the scattering type liquid crystal panel. In this correction, the operating state of the control circuit 120 is detected from the decoded signal from the decoder 129, and the correction is performed in synchronization with the control circuit so that the change in the average intensity of the drive signal becomes smaller. Therefore, when the originally dark projected image becomes darker due to the smaller converging angle, the brightness of the scattering liquid crystal panel is corrected to the opposite direction, and the brightness of the finally obtained projected image fluctuates. Is alleviated.

As described above, when the input signal A is set to be constant at the intermediate signal fixed value shown in FIG. 12, the signal C from the photosensor interface circuit 124 is next changed. The aperture is controlled based on the above.

Next, the average video level (APL) detection circuit 140 in the display device shown in FIG.
~ It demonstrates concretely with reference to FIG.

In the average video level (APL) detection circuit 140 shown in FIG. 14, a positive video signal is input from the input terminal 151 and applied to the collector of the transistor 174 via the coupling capacitor-171. A voltage obtained by dividing the power supply voltage V _CC supplied to the power supply terminal 161 by the resistors 172 and 173 is biased to the collector of the transistor 174.

The base of the transistor 174 has a terminal 1
A gate pulse is applied from 62 through resistor 175. In the transistor 174, the average video level (APL) is detected during the gate pulse. The detected period is, for example, a blanking period of the video signal.

Next, the detected APL is peak rectified by a time constant circuit composed of a rectifying diode 177, a resistor 178 and a capacitor -179 via a buffer transistor 176, and a transistor 180 and a resistor 181 are connected. The following signals are obtained via the buffer amplifier composed of the following and the resistor 182.

FIG. 15 shows that in the case of a video signal having a low APL,
And a transistor 17 for a high APL video signal
4 shows the collector input of 4, the emitter output of the buffer transistor 176, and the emitter output of the buffer transistor 180. From FIG. 15, the buffer transistor 180
It can be seen that the emitter output of is low when the APL is low and high when the APL is high. This voltage change is obtained via the resistor 182.

FIG. 16 is a circuit diagram showing another example of the APL detection circuit. For example, it is assumed that a video signal in which the tip of the sync signal is clamped is input to the terminal 151. Here, the transistor 190 is connected to the power supply terminal 161 via a parallel circuit composed of a resistor 191 and a capacitor 192, and the emitter of the transistor 190 is connected to a reference potential point via a resistor 193 and a Zener diode 194. ing.

The collector of the transistor 190 is a PNP.
Type transistor 195 connected to the base of
The emitter of the P-type transistor 195 is connected to the power supply terminal 1 via a parallel circuit including a resistor 196 and a capacitor 197.
62 and is also connected to the base of transistor 180. The transistor 180 and the resistor 182 are the same as those shown in FIG.

In the circuit of the configuration shown in FIG. 16, when a clamped video signal is input to the base of the transistor 190, the collector of the transistor 190 outputs a level higher than the threshold value set by the Zener diode 194. Signal is repeatedly amplified and output. This signal is rectified by the base emitter of transistor 195 and taken out through transistor 180.

The reference voltage at the input terminal (-) of the error amplifier 150 changes due to the emitter output of the transistor 180. By doing so, the transistor 19
The collector input of 0 and the emitter output of the buffer transistor 195 are as shown in FIG. Note that, in FIG. 17, the hatched portion indicates the transistor 1
This is the part amplified by 95, and the part below this threshold value is rectified through the base-emitter of the transistor 180.

When the display device having the structure shown in FIG. 12 described above is operated for display in a dark room, the contrast is 1.1 × 10 −3 sr due to insufficient characteristics of the polymer dispersed liquid crystal.
70: 1 in the case of, and 18: in the case of 8.6 × 10 −3 sr.
The contrast was 1. The amount of light when displaying white is
18 lm when the collection angle is 1.1 × 10 -3 sr,
In the case of 8.6 × 10 -3 sr, the display was 75 lm.
When the diaphragm is fixed, it is necessary to use the diaphragm in the condition of 1.1 × 10 −3 sr where the converging angle becomes the minimum in order to obtain sufficient contrast. On the other hand, in the case of being variable as in the embodiment, the overall brightness can be increased in a bright scene, and thus the display impression is dramatically improved. In particular,
When the display operation is performed using video software that contains images of constellations and the moon world, the background black is tightened in the constellation scene, and the display is quite different from when the aperture is fixed. . Regarding the relationship between the average change in brightness and the aperture adjustment speed, the aperture adjustment time constant is set to 0.5.
When set to about 1 second to 1 second, the display characteristics could be improved without feeling any unnaturalness.

Next, when a display was performed in a 500 lux room using a screen with a reflection gain of 13 times, the brightness of the screen due to the room light was considerably anxious, and the converging angle was almost maximum. The best impression was obtained when set to. This setting is a bad setting compared to the case where the converging angle is made smaller, because the lack of contrast becomes more of a concern when the room is sufficiently dark. It was confirmed that when the display device of this example was used, the display operation could be performed by optimizing the display characteristics even if the brightness of the usage environment was different.

In a bright environment, the human sense recognizes a dark portion as black for its brightness, and therefore, in a bright scene, the requirement for black display is not so strict. In this case, it is important that the white part is sufficiently bright rather than the contrast.

On the contrary, in a dark scene, the sense is sensitive to darkness so that the distinction between light black and dark black becomes clear. The brightness of the white part is emphasized by comparison with the surrounding black part, so the absolute brightness of the white part is not so important. In this case, it is required that the contrast is good and black is displayed sufficiently dark. The projection type display device of this embodiment can change the display characteristics so as to satisfy the human sense, and can also obtain the display characteristics which have not been obtained in the past. That is, the substantial brightness can be improved under sufficient contrast.

This projection type display device is actually used in various environments depending on the time zone or place. In particular, since the outside light (indoor lighting, the lighting portion of the window) acts on the screen to determine its brightness, the black image portion is very susceptible. That is, if the periphery of the screen is too bright, the contrast of the image displayed on the screen is lowered even if the output light from the display device has a good contrast. Therefore, in such a state, the display in which the brightness is prioritized over the contrast is performed. Further, in a sufficiently dark room or the like, even if the white display is a little dark, the display is made so that the black appears to be solid.

In the projection type display apparatus of this embodiment, it is possible to arbitrarily select whether to give priority to black display or white display depending on various conditions of the surrounding environment. Further, this display device has low power consumption despite having the above-mentioned good display performance.

Although the reflective screen SC is used for viewing the display image on the front side in the above-described embodiments, the transmissive screen may be used for viewing the display image on the rear side. .

Further, in this embodiment, the display device is configured to utilize the transmitted light of the scattering type liquid crystal panel provided as the light modulation element, but is configured to utilize the reflected light of the scattering type liquid crystal panel. May be. This scattering type liquid crystal panel may have, for example, a fine particle dispersion type liquid crystal layer as a light modulation layer instead of the polymer dispersion type liquid crystal layer. Also,
The scattering type liquid crystal panel may be changed to a light modulation element such as DMD.

The display device according to the present embodiment can display an image brighter in a bright scene and darker in a dark scene, and the effective contrast and brightness are improved. This is because the display characteristics change depending on the state of the diaphragm as shown in FIG. In FIG.
The state of the diaphragm is shown in the form of an angle at which the light flux emitted from the light modulation element passes through the diaphragm, that is, a converging angle. When the converging angle is small, the display is dark as a whole, but especially in the case of black display, the display is dark and the contrast is good. On the other hand, if the converging angle is increased, not only the white display but also the black display becomes brighter and the contrast becomes smaller. On the other hand, the maximum brightness and the minimum brightness can be used for display by changing the converging angle according to the brightness of the display.

Further, in a bright environment, it is possible to obtain a display characteristic in which brightness is emphasized, and in a dark environment, a high-contrast display characteristic in which a black level is emphasized can be obtained. That is, as shown in FIG. 19, when the brightness of the display screen is constantly above a certain level due to external brightness, the black level does not drop below that level, so that even if the output light flux of the display device decreases. It doesn't make much sense.
Therefore, in this case, by displaying with emphasis on brightness by opening the diaphragm, the overall display characteristics including the environment are improved.

As described above, according to the second aspect, it is possible to appropriately control the contrast and brightness of the image displayed on the screen.

Next, a third embodiment of the present invention will be described.

In the display device according to the first and second aspects, or in the conventional display device, when the converging angle of the diaphragm is adjusted, a desired transmitted light intensity is generated corresponding to the luminance signal voltage. It becomes impossible to obtain it under the driving voltage. That is, the gradation of the display image cannot be accurately reproduced. Further, when the modulator displays a color image composed of red, green, and blue color components, the gradation balance between these color components changes with a change in the converging angle, thereby changing the color tone of the display image. Will result.

In the above-mentioned projection type display device,
Although it is possible to optimize the display state under various environments, the angular distribution of the light rays incident on the liquid crystal panel is different between when the brightness priority display is performed and when the contrast priority display is performed. There is a decrease in contrast and deterioration in display quality due to. The deterioration of the display quality is caused by the fluctuation of the light leak current of the pixel switch element of the liquid crystal panel due to the change of the luminous flux incident on the liquid crystal panel.

The third aspect of the present invention has been made in view of the above-mentioned technical problems, and is to accurately reproduce the gradation of an image and to obtain a good display image in various environments. Provided is a projection display device having excellent display quality even when used in a particularly bright environment.

First, according to the inventors' consideration of the converging angle control dependency of the drive voltage-modulated light intensity characteristic of the modulation element in the case where the liquid crystal panel has no light leak, the drive voltage of the modulation element is examined. The modulated light intensity characteristic is as shown in FIG.
In FIG. 20, a characteristic curve Y1 represents a relative relationship between the drive voltage of the modulation element and the transmitted light (modulated light) intensity obtained at a standard converging angle of 5 degrees. This characteristic curve Y1
Shifts as shown by a curve Y2 when the diaphragm is opened, and shifts as shown by a curve Y3 when the diaphragm is narrowed. This changes the transmitted light intensity for the same drive voltage. For example, when the characteristic curve Y1 of the modulator is shifted to the curve Y2, the transmittance of the modulator is, as shown in FIG. 21, less than 0.6 which is a value to be set for the luminance signal voltage of 0.6V. Is also set to a high value.

The dependency of the driving voltage-modulated light intensity characteristic on the diaphragm is considered to be due to the reason described below. That is, the distribution of the incident light flux with respect to the modulator is equal to the distribution of the outgoing light flux determined by the focusing angle of the diaphragm, as shown in FIG. As shown in FIG. 23, the modulation element has a scattering property to scatter light, and when the converging angle of the diaphragm changes as indicated by A, B, and C in FIG. The angles A, B, and C are distributed as shown in FIGS. 24A, 24B, and 24C, respectively.

However, these emitted light fluxes are blocked by, for example, a diaphragm on the emission side except for a portion in the same constant angle range as the distribution of the incident light flux, so that only the hatched portions in these figures are involved in the display. Is effective as an outgoing light flux. As is clear from these figures, the ratio of the effective portion to the light-shielding portion becomes larger as the converging angle becomes wider.

The relative transmissivity of the modulator is determined by the amount of the luminous flux of the outgoing luminous flux which does not scatter all the incident luminous flux in the modulator and passes through the diaphragm on the outgoing side, and the diaphragm on the outgoing side when scattered by the scattering property of the modulating element. It is the ratio to the luminous flux amount of the outgoing luminous flux that passes through. In the case where the modulator has the scattering property as shown in FIG.
The transmittances of the aperture amounts as shown in A, B, and C in FIG.
As shown in (b) and (c). That is, it can be seen that the wider the converging angle is, the larger the ratio of the outgoing light flux passing through the exit-side diaphragm to the incoming light flux becomes.

According to the display device of the third aspect of the present invention, the compensating circuit interlocks with the aperture controller to compensate for the change in the drive voltage-modulated light intensity characteristic of the modulator. For this reason, even when the aperture amount is adjusted to change the brightness of the image, it is possible to appropriately perform the gamma correction. Therefore, it is possible to prevent gradation deterioration and unnatural change in color tone.

A projection type display device according to the third aspect of the present invention will be described below with reference to the drawings.

FIG. 25 shows the overall construction of this projection type display device. This projection type display device has a spheroidal mirror 1
01, the light source lamp 102, the electric diaphragm 104, the condenser lens 103, the scattering type modulation element 108, the field lens 109, the projection lens group 110, and the electric diaphragm 111.
Have an optical system arranged on the optical axis. The light obtained from the lamp 102 is reflected by the mirror 101 directly and enters the condenser lens 103. Condenser lens 10
Reference numeral 3 designates a modulation element 10 which makes the incident lights parallel to each other.
8. The modulator 108 modulates the spatial propagation direction of incident light in a two-dimensional area, and includes a gamma correction circuit 210 and a polarity inversion / non-inversion amplifier circuit 21.
It is driven by a drive circuit configured by 1.

The modulation element 108 is a polymer dispersion type liquid crystal panel in which a liquid crystal layer in which a liquid crystal material is dispersed in a polymer resin is held between a pair of transparent electrode substrates, and a plurality of color pixel groups are arranged in a matrix in the liquid crystal panel. Arranged. Each pixel group consists of red, green and blue pixels. The field lens 109 guides the modulated light from the modulation element 108 to the projection lens group 110, and the projection lens group 11
0 projects this modulated light on a reflective screen. That is,
The basic display principle of this projection type display device is the same as the conventional one.

In this display device, the electric diaphragm 104 is arranged between the light source lamp 102 and the condenser lens 103, and the electric diaphragm 111 is arranged in the projection lens group 110. The motorized diaphragm 104 restricts the luminous flux of the light source light from the light source lamp 102 to control the angular range of the light rays incident on the modulation element 108, and the motorized diaphragm 111 modulates to control the angular range of the light rays projected on the screen 109. Element 10
The modulated light flux from 8 is narrowed down. Motorized diaphragms 104 and 1
Each of 11 has five ceramic blades having excellent heat resistance and a servo motor, and the converging angle is changed by changing the size of the circular opening formed by the combination of the ceramic blades, that is, the radius by the servo motor. It functions as a circular variable diaphragm.

This display device displays a color video signal in red,
Three luminance signals R, G, and B obtained by decomposing into green and blue color components are supplied. Each brightness signal sequentially specifies the brightness of the pixel of the corresponding color provided in the modulation element 108 in one field cycle. The display device further includes a diaphragm control circuit for commonly adjusting the converging angles of the motorized diaphragms 104 and 111, that is, the opening radius based on the luminance signals R, G, and B in order to optimize the contrast and brightness of the displayed image. 212.

This aperture control circuit 212 uses the gamma correction circuit 21 to obtain the focused-angle data D representing the adjusted focused angle of the aperture.
Supply 0. The gamma correction circuit 210 uses the light collection angle data D
Gamma-corrects the luminance signals R, G, and B based on
This is supplied to the polarity inversion / non-inversion amplifier circuit 211 as the drive voltages RO, GO, and BO. The polarity inversion / non-inversion amplifier circuit 211 inverts the polarities of the drive voltages RO, GO, and BO from one of the positive polarity and the negative polarity to the other in the horizontal scanning cycle of the video signal, and supplies the polarity to the modulation element 108.

FIG. 26 shows the structure of the gamma correction circuit 210 in more detail. The gamma correction circuit 210 performs the gamma correction on the luminance signals R, G, and B, respectively, and has processing channels CH1-CH configured in the same manner as each other.
3 Each of these processing channels CH1-CH3 has an A / D converter 201 for converting the luminance signal of the corresponding color into luminance data I in digital format representing the luminance of each pixel, and the luminance data I from this A / D converter 201. , A gamma characteristic conversion table 202 for generating reference drive voltage data VR corresponding to, a correction table 203 for generating correction data ΔV corresponding to the condensing angle data D from the aperture control circuit 212,
It is composed of an adder 204 that adds the correction data ΔV to the reference voltage data VR, and a D / A converter 205 that converts the addition result into an analog drive voltage signal.

The characteristic conversion table 202 is a ROM storing a plurality of reference drive voltage data VR selected by the brightness data I, and each reference drive voltage data VR is shown in FIG. 22 for the brightness specified by the brightness data I. The reference drive voltage determined by the characteristic curve Y1 is shown. The correction table 203 is a ROM that stores a plurality of correction data ΔV selected by the brightness data I, and each correction data ΔV is represented by curves Y2 and Y3 obtained with respect to the light collection angle specified by the light collection angle data D. The correction voltage approximates the difference between such a curve and the characteristic curve Y1.

The operation of each processing channel will be described. The A / D converter 201 converts the luminance signal into luminance data I and supplies it to the gamma characteristic conversion table 202. As a result, one of the reference drive voltage data VR stored in the gamma characteristic conversion table 202 is selected by the brightness data I, and the gamma correction based on the characteristic curve Y1 obtained at the standard converging angle of 5 degrees is performed. As a result, it is supplied to the adder 204. On the other hand, one of the correction data ΔV stored in the correction table 203 is the aperture control circuit 2
12 is supplied to the adder 204 as a correction voltage that approximates the difference between the characteristic curve Y1 selected by the condensing angle data D and obtained for the converging angle specified by the converging angle data D. It The adder 204 adds the reference drive voltage data VR and the correction data ΔV. The result of this addition represents a drive voltage suitable for the current focusing angle and is converted into a drive voltage signal by the D / A converter 205.

When the motorized diaphragms 104 and 111 are set to a standard converging angle of, for example, 5 degrees, the correction data Δ
Since V represents zero, the addition result of the adder 204 becomes equal to the reference drive voltage data VR. When the light collection angle data D changes due to the adjustment of the light collection angle, the correction data ΔV also changes from zero to the positive or negative direction. The correction data ΔV becomes negative when the light collecting angle of the diaphragm is larger than 5 degrees, and becomes positive when the light collecting angle of the diaphragm is smaller than 5 degrees. Since the modulator 108 using the polymer-dispersed liquid crystal is an element whose light scattering property is lowered and the modulated light intensity is increased by applying a voltage, the driving voltage becomes smaller as the converging angle of the diaphragm increases, and the driving voltage of the diaphragm becomes smaller. The larger the light angle, the larger the correction.

In this display device, two electric diaphragms 104 are provided.
And 111 are provided, and the substantial characteristics of the gamma correction circuit 210 change with the adjustment of these light collection angles. As a result, the drive voltage is appropriately corrected with respect to the converging angle of the diaphragm, so that the luminance specified by the luminance signal can be obtained without depending on the converging angle. That is, when the converging angle of the diaphragm changes, the gradation is not collapsed and the unnatural color tone is not changed.

In the above-mentioned embodiment, the converging angles of the electric diaphragms 104 and 111 are similarly changed, but only one of them may be changed. Further, the modulation element 108 may use, for example, a fine particle dispersion type liquid crystal or DMD, a liquid crystal diffraction grating by an oblique electric field, instead of the polymer dispersion type liquid crystal. When a modulator that increases the light scattering property and decreases the modulated light intensity when a voltage is applied is used, it increases as the converging angle of the diaphragm increases and decreases as the converging angle of the diaphragm decreases. The contents of the correction table 203 are changed to correct the error.

The correction table 203 is set to 1 for each converging angle.
A plurality of pieces of correction data ΔV, each of which holds the correction data ΔV, represents the voltage of the difference between the curves such as the curves Y2 and Y3 obtained for each converging angle and the reference characteristic curve Y1 for each luminance.
May be held. In this case, each correction data ΔV is selected by a combination of the brightness data I and the light collection angle data D. With such a configuration, the storage capacity of the correction table 203 must be increased, but more detailed correction can be performed.

Further, as in the above-mentioned embodiment, the modulation element 1
Instead of guiding the transmitted light of 08 to the screen 109, the reflected light of the modulation element 108 may be guided to the screen 109. Further, the screen 109 is not limited to the reflective type used for viewing the display image on the front side, but may be the transmissive type used for viewing the display image on the rear side.

As described above, according to the third aspect of the present invention, the converging angle of the diaphragm is optimized based on the surrounding environment and the state of the display image, while the gradation of the display image is accurate. Can be reproduced.

As described above, even when there is no optical leak of the switching element of the modulation element 108, it is necessary to control the drive voltage-modulated light intensity characteristic according to the change of the converging angle by the diaphragm. In an actual modulator, considering the aperture ratio, it is difficult to sufficiently shield the switch element from light, and in addition to the control of the aperture diameter of the diaphragm 52, the modulator 10 has a large aperture.
Since the intensity of the light flux incident on the beam 8 also changes, it is also necessary to control the drive voltage-modulated light intensity characteristic in consideration of the optical leak of the switch element. When the optical leak of the switch element occurs, the pixel potential holding characteristic deteriorates, and the driving voltage-modulated light intensity characteristic shifts to the high voltage side. Since this light leak current is proportional to the intensity of light incident on the switch element, the parallel shift amount increases with the incident light flux increasing in proportion to the aperture diameter of the diaphragm 52, and the same display quality deterioration as described above occurs. For this reason, it is desirable to optimize the light-shielding structure of the switch element and use a polysilicon TFT for the switch element rather than an amorphous silicon TFT, but more desirably, a video signal control means for correcting the light leak characteristic of the modulator element is provided. Good.

Furthermore, when a color image is formed by the modulators composed of red, blue and green color components, the light intensity incident on these modulators also differs depending on the color. Since the characteristics also have wavelength dependence, it is desirable to prevent the gradation balance between the color components from changing with a change in the converging angle and changing the color tone of the display image.
In practice, it is desirable to correct the drive voltage of the modulator-the modulated light intensity, including the optical leak that accompanies each aperture diameter control.

Next, the fourth aspect of the present invention will be described.

As described above, it is necessary to control the drive voltage-modulated light intensity characteristic in accordance with the change of the converging angle by the diaphragm even when there is no light leak of the switching element of the modulation element 108. In addition to it being difficult to sufficiently shield the switch element with the modulation element 108 in consideration of the aperture ratio, the modulation element 108 is controlled by controlling the aperture diameter of the diaphragm 52.
Since the intensity of the light flux incident on the light source also changes, it is necessary to control the drive voltage-modulated light intensity characteristic in consideration of the light leak of the switch element.

When the optical leak of the switch element occurs, the pixel potential holding characteristic deteriorates, and the driving voltage-modulated light intensity characteristic shifts in parallel to the high voltage side. Since this light leak current is proportional to the intensity of light incident on the switch element, the parallel shift amount increases with the incident light flux increasing in proportion to the aperture diameter of the diaphragm 52, and the same display quality deterioration as described above occurs. . For this reason, it is desirable to optimize the light-shielding structure of the switch element and use a polysilicon TFT for the switch element rather than an amorphous TFT.
It is preferable to provide a video signal control means for correcting the black characteristic. Furthermore, when the modulation element is composed of red, blue, and green color components and a color image is displayed, the light intensity incident on these modulation elements also differs depending on the color, and the light leak characteristics of the switch element are different. Also, since there is wavelength dependency, it is desirable that the gradation balance between the color components changes with the change of the converging angle, and the change of the color tone of the display image is suppressed. In practice, it is desirable to correct the driving voltage-modulated light intensity characteristic of the modulator, which also includes the optical leak that accompanies each aperture diameter control.

In a display device using a polymer-dispersed liquid crystal or a fine-particle-dispersed liquid crystal, the display state changes depending on the display brightness and as time passes from the initial display, and the display quality changes depending on the ambient temperature. There is a problem of doing. This is because the applied voltage (V) -light transmittance (T) characteristic, the hysteresis characteristic, the response speed, and the like of the polymer-dispersed liquid crystal and the fine-particle-dispersed liquid crystal change with temperature change. It is considered that the fluctuation amount is larger than that of the twisted nematic (TN) type liquid crystal.

Further, particularly in the case of the projection type display device,
There is also a problem that the display quality is deteriorated due to the temperature difference caused by the light flux that changes according to the control of the aperture diameter of the diaphragm arranged in the light source optical system.

The fourth aspect of the present invention has been made in view of the above technical problem, and does not depend on the size of the diaphragm for controlling the luminous flux, the elapsed time from the lighting of the light source, or the environmental temperature condition. Or a display device that can obtain an excellent display image even during continuous display.

That is, the modulation element provided with a liquid crystal layer of a polymer dispersion type in which a liquid crystal material is contained in a polymer resin or a fine particle dispersion type in which fine particles are contained in a liquid crystal material is applied as described above. The voltage (V) -light transmittance (T) characteristic, the hysteresis characteristic, the response speed, and the like greatly change with temperature changes.

In FIG. 27, the ordinate represents the voltage (V50) at which the light transmittance is 50%, and the abscissa represents the temperature (T), showing the temperature dependence of the modulator. As you can see from this figure,
In order to obtain a constant display image without depending on the temperature (T), it is necessary to increase the voltage applied to the liquid crystal layer as the temperature (T) rises.

Therefore, in the fourth aspect of the present invention, the video signal control means for increasing / decreasing the video signal according to the temperature change of the modulator is provided. Accordingly, a constant display image can be obtained without depending on the temperature (T).

FIG. 28 is a diagram showing a projection type liquid crystal display device according to the fourth embodiment of the present invention.

As shown in FIG. 28, this projection type liquid crystal display device 300 is a three-plate type, that is, three modulation elements for red (R), green (G) and blue (B), for example, a liquid crystal panel 30.
1-R, 301-G, 301-B.

In the light source optical system of this display device, a metal halide lamp is arranged as the light source 311.
Light from the light source 11 is emitted from the light source 311 and the liquid crystal panel 301-
R, 301-G), 301-B, and a spheroidal reflector 3 that focuses the light at a point A on the optical axis.
21 is provided. The light source light once condensed at the point A by the reflector 321 passes through the cold mirror 331 and is then guided by the collimator lens 341 to the liquid crystal panels 301-R, 301-G, and 301-B as parallel light. In addition, the point A, which is the focus position of the reflector 321,
Has a substantially circular opening, and a first diaphragm means 351 whose opening diameter D ₁ can be varied by a servomotor is arranged.

Also, in this display device, the light source 311 is
Since the position accuracy with respect to the reflector 321 is simplified, the reflector 321 is fixedly arranged at the central portion of the reflector 321.
The luminous flux at the central portion of the light source light from the light source 311 becomes small. Therefore, in the light source optical system of this display device, the light source 3
A convex conical lens 361 is disposed on the first diaphragm means 351 side between the lens 11 and the first diaphragm means 351. The conical lens 361 guides a light beam that is diverged and is not effectively used, to the central portion, thereby preventing a decrease in the light flux in the central portion of the light source light. In addition to the convex conical lens 361, a concave conical lens may be used as long as it guides a light beam that is diverged and is not effectively used, to the central portion, as disclosed in JP-A-6-175129. It may have a different structure.

The projection optical system includes liquid crystal panels 301-R, 3
01-G, 301-B modulated light is modulated by point B
A converging lens 501 for condensing the light at a point B has an opening that blocks scattered light from each of the liquid crystal panels 301-R, 201-G, and 201-B at point B and allows transmitted light to pass therethrough, and its opening diameter D ₂ Is composed of a second diaphragm means 503 which is variable by a servo motor, and a projection lens 505 for projecting the modulated light after passing through the second diaphragm means 503. As described above, the second diaphragm means 503 blocks the scattered light from each of the liquid crystal panels 301-R, 301-G, and 301-B and allows the transmitted light to pass therethrough.
The display brightness can be increased by increasing the opening diameter D ₂ of the second diaphragm means 503.

The first diaphragm means 351 and the second diaphragm means 503 use the first diaphragm means 351 and the second diaphragm means 503 based on the environmental brightness signal ES from the optical sensor 711 for monitoring the environmental brightness on the screen. It is electrically connected to the aperture control means 721 for controlling the opening diameters D ₁ and D ₂ of the aperture 503. More specifically, the aperture diameter D ₂ of the opening diameter D ₁ and the second throttle means 503 of the first throttle means 351, the aperture control unit 721, converging angle Omega ₁ as brightness on the screen is high, Omega ₂ are controlled to be large, and in this display device, the collection angles Ω ₁ and Ω ₂ are from 8.6 × 10 ⁻³ sr to 1.
The opening diameters D ₁ and D ₂ of the first diaphragm means 351 and the second diaphragm means 503 are variable so as to be variable in the range of 1 × 10 ⁻³ sr.
Is controlled.

The first diaphragm means 35 in this specification.
Convergence angle Ω based on 1₁Is the distribution angle of the light source is ± θ
Then, [2π sin θ] is integrated with respect to θ from 0 to θ.
It is expressed by the value₁The collimator
The focal length of the lens 341 is f ₁As the first diaphragm means
351 opening diameter D₁When expressed as a function of₁= Π (D₁
/ 2f₂)²It is expressed by.

Also, the second diaphragm means 5 in the present specification.
When the focal length of the field lens is f ₂ and it is expressed as a function of the aperture diameter D ₂ of the second diaphragm means 503, the converging angle Ω ₂ based on 03 is Ω ₂ = π (D ² · f ₂ ) ² . Expressed.

Considering the light utilization efficiency and the like, it is desirable that the light collection angles Ω ₁ and Ω ₂ be interlocked and varied so as to substantially match.

Next, each liquid crystal panel 301-R, 301-
The arrangement of G and 301-B will be described. As for the light source light from the light source optical system, only the green (G) light is reflected by the first dichroic mirror 411-D, and the first total reflection mirror 4
Green (G) light is guided to the liquid crystal panel 301-G via 11-A, and is emitted through the liquid crystal panel 301-G and the green (G) field lens 421-G.

The source light that has passed through the first dichroic mirror 411-D is converted into the second dichroic mirror 413.
Only red (R) light is reflected by -D, and the liquid crystal panel 3
01-R. Then, the liquid crystal panel 301-R,
Red (R) through red (R) field lens 421-R
The light is emitted from the liquid crystal panel 3 by the first synthetic mirror 411-M.
It is combined with green (G) light that has passed through 01-G.

The light source light transmitted through the second dichroic mirror 413-D is guided to the liquid crystal panel 301-B, and the liquid crystal panel 301-B and the blue (B) field lens 42.
The blue (B) light passing through 1-B is reflected by the second total reflection mirror 413.
The red (R) light and the green (G) light that have been transmitted through the liquid crystal panel 301-G and the liquid crystal panel 301-R by the second combining mirror 413-M via -A and are combined to form a projection optical system. Be guided.

Next, the liquid crystal panels 301-R and 301
-G and 301-B will be described. The liquid crystal panel 3
The configurations of 01-R, 301-G, and 301-B are the same except for the drive system thereof, so that the liquid crystal panel 3 for green (G) is used.
01-G will be described as an example. This liquid crystal panel 301-
G has 100 micron pitch display pixels in the horizontal direction 64
It consists of 0 pieces and 480 pieces arranged in the vertical direction.

The liquid crystal panel 301-G is shown in FIGS.
As shown in FIG. 0, the polymer-dispersed liquid crystal layer 401 in which the nematic liquid crystal exhibiting positive dielectric anisotropy is dispersed in the polymer resin between the array substrate 511 and the counter substrate 611 is the surface treatment film 591. , 691.

The array substrate 511 is a transparent glass substrate 510 having a thickness of 0.7 mm and a signal line 52 as shown in FIG.
1 and the scanning line 531 are arranged so as to be substantially orthogonal to each other, and a thin film transistor (hereinafter abbreviated as TFT) 541 is arranged near the intersection of the signal line 521 and the scanning line 531. As shown in FIG. 30, this TFT 541 uses the scanning line 531 itself as a gate electrode, and protects the amorphous silicon thin film 545 and the amorphous silicon thin film 545 as a semiconductor layer on the scanning line 531 via the gate insulating film 543. In addition, the semiconductor protective film 546 made of silicon nitride self-aligned with the scanning line 531 to suppress the parasitic capacitance, the amorphous silicon thin film 545, and the signal line 521 are electrically connected via the n ⁺ -type amorphous silicon thin film 548. Signal line 5 that is electrically connected
21 drain electrode 547 and signal line 521
I arranged in a region surrounded by the scanning line 531 and the scanning line 531.
Inverted stagger structure including a pixel electrode 551 made of TO (Indium Tin Oxide) and a source electrode 549 electrically connecting an amorphous silicon thin film 545 through an n ⁺ -type amorphous silicon thin film 550. Is. Further, the auxiliary capacitance line 553 for forming an auxiliary capacitance (Cs) with the pixel electrode 551 via the gate insulating film 543 is the scanning line 5.
It is arranged substantially parallel to 31. Furthermore, these TFTs
An array substrate 511 is configured by disposing a protective film 555 on the 541 and the pixel electrode 551.

The counter substrate 311 is the TFT 541 of the array substrate 511 on the transparent glass substrate 310 having a thickness of 0.7 mm.
And a matrix-shaped light-shielding layer 313 made of chromium (Cr) for shielding the periphery of the pixel electrode 551, a protective film 317 arranged on the light-shielding layer 313, and a counter electrode 319 made of ITO arranged on the protective film 317. It is composed of and. The liquid crystal panel 301-G configured as above achieves an aperture ratio of 40%.

Further, in this display device, as shown in FIG. 31, a temperature sensor 800 is arranged in the vicinity of the display portion on the incident surface of the liquid crystal module, and the drive voltage is supplied based on the temperature signal (TS) from this temperature sensor 800. The brightness signal (BS) input to the supply circuit 731 is controlled, and the video signals V _SR , V _SG , and _{VS B} are supplied to the liquid crystal panels 301-R, 301G, and 301B via the polarity inversion / non-inversion amplifier 741. To be done.

As the temperature sensor, for example, μPC39
11 (trademark, manufactured by NEC Corporation) can be used. Since this IC integrates a reference voltage, a temperature sensor, and a phase correction built-in operational amplifier in the same chip, it requires few external circuit components. Furthermore, the linearity is very excellent as compared with the conventional temperature sensors such as thermistors, and high-performance temperature measurement is possible. A specific circuit is shown in FIG.

As shown in FIG. 28, the drive voltage supply circuit 73 is based on the temperature signal (TS) from this temperature sensor.
The brightness signal (BS) input to 1 is controlled, and each liquid crystal panel 301-is controlled via the polarity inverting / non-inverting amplifier 751.
R, 301-G, 301-B each video signal (VSR),
(VSG) and (VSB) are supplied.

As shown in FIG. 33, the drive voltage supply circuit 731 converts the input brightness signal (BS) into a digital signal by the analog-digital converter 733 and converts the digitalized brightness signal (BS) into ROM. The configured gamma correction circuit 734 performs gamma correction, and the gamma-corrected digital luminance signal is supplied to one input terminal of the adder 735. In addition, the temperature signal (TS) from the temperature light sensor
Based on the temperature compensation circuit 736 composed of the ROM, the compensation data for correcting the temperature dependence of the light transmittance (T) -voltage (V) characteristic of the liquid crystal panel 301-G is supplied to the other input terminal of the adder 735. Is supplied to. The adder 735 outputs the addition output of the digital luminance signal and the compensation data to the digital / analog converter 737. And
An analog signal is output from the digital / analog converter 737 to the polarity inverting / non-inverting amplifier 731.

The polarity inversion / non-inversion amplifier 731 amplifies the analog signal to a signal level required for the liquid crystal panel 301-G, and inverts the polarity with respect to the reference potential at a predetermined frequency for each field period and each scanning period. Image signal (VSG) to be supplied to the liquid crystal panel 301-G.

In addition, other liquid crystal panels 301-R, 301
Similarly, in -B, the video signals (VSR) and (VSB) corrected based on the temperature signal (TS) from the temperature sensor provided in the liquid crystal panel 301-G are liquid crystal panels 301-R and 3B.
01-B.

More specifically, this gamma correction circuit 734
Is configured so that the brightness signal (BS) input based on the voltage (V) -light transmittance (T) characteristics in the state where the temperature inside the liquid crystal panel 301-G is 40 ° C. is gamma-corrected. For example, the temperature inside the liquid crystal panel 301-G is 40
With reference to ° C, the compensation data from the temperature compensation circuit 746 increases to the positive side as the temperature rises above 40 ° C.
The compensation data from the temperature compensation circuit 746 decreases to the negative side as the temperature drops below 0 ° C.

The rotation speed of the panel cooling fan is controlled according to the panel temperature monitored by the temperature sensor,
When the temperature of the panel is controlled, the video signal can be controlled more accurately according to the temperature of the panel. Therefore, it is desirable to control the cooling fan based on the output of the temperature sensor. In addition, for example, when the panel temperature rises immediately after turning on the light source, the rotation of the cooling fan is stopped for a certain period, or the number of rotations is kept low to shorten the time required to reach the temperature during steady operation. It is desirable to control it.

As described above, this projection type liquid crystal display device 3
00, each liquid crystal panel 301-R, 301-G,
Since the display state is optimized according to the temperature change of 301-B, the projection type liquid crystal display device 30 is operated at a relatively low room temperature, for example.
0, the light source 311 is turned on, and each liquid crystal panel 301
It takes time for each of -R, 301-G, and 301-B to reach a certain temperature, for example, the temperature of each liquid crystal panel 301-R, 301-G, and 301-B changes for about 3 to 30 minutes. Even in the case of continuing the operation, appropriate driving is always performed, and a good display image can be obtained without causing color unevenness and the like.

In particular, according to this display device, the opening diameters D _{1 of} the first diaphragm means 351 and the second diaphragm means 503,
Since D ₂ is variable according to the screen brightness, the intensity of light incident on each liquid crystal panel 301-R, 301-G, 301-B varies depending on the opening diameter D ₁ of the first diaphragm means 351. Because of the difference, each liquid crystal panel 301-R, 301
The degree of temperature rise of -G and 301-B also changes.

That is, when the screen brightness is small, it is recognized that the display image is visually good because the contrast ratio is higher than the display brightness, so that the aperture diameter D ₁ of the first diaphragm means 351 is narrowed. On the other hand, when the screen brightness is high, the display brightness is emphasized, so that the opening diameter D ₁ of the first diaphragm means 351 can be opened. Therefore, the larger the screen brightness is, the more liquid crystal panels 301-R, 3
The degree of temperature rise of 01-G and 301-B becomes high.
For example, according to this embodiment, the liquid crystal panel 301 is actually used.
When the collection angle Ω _{1 of the} light source light incident on −R, 301-G, and 301-B changes from 8.6 × 10 ⁻³ sr to 1.1 × 10 ⁻³ sr, each liquid crystal panel 301-R, 301-G, 301
-B temperature varies by 3-5 ° C.

However, according to this embodiment, a temperature sensor is arranged on the liquid crystal panel 301-G and monitored at any time to optimize each video signal (V _SR ), (V _SG ), (V _SB ). Therefore, the opening diameter D _{1 of} the first diaphragm means 351 is changed, and the condensing angle Ω ₁ of the source light is increased or decreased,
Even if the liquid crystal panels 301-R, 301-G, and 301-B change in temperature, a good display image can be obtained.

In this display device, the first diaphragm means 3 is used.
51 and the aperture diameters D ₁ and D _{2 of} the second diaphragm means 503 are controlled by the first diaphragm means 721 according to the environmental brightness signal (ES).
-R, 301-G, 301-B based on the video signals (V _SR ), (V _SG ), (V _SB ), the aperture diameter D of the first diaphragm means 351 and the second diaphragm means 503. ₁ , D
₂ may be controlled. That is, on the basis of the difference between the temporal average intensity of the brightness signal (BS) and the blanking level (black level) of the brightness signal, if the difference is small, the aperture diameters D ₁ and D ₂ are reduced to collect light at an angle Ω. ₁ and Ω ₂ are controlled to be small, and when the difference is large, the opening diameters D ₁ and D ₂
And a large control of the converging angles Ω ₁ and Ω ₂ ensure a good display image.

Further, the first diaphragm means 351 and the second diaphragm means 503 have the environmental brightness signal (ES) and the brightness signal (B).
It may be controlled according to each of S).

In this display device, the polymer-dispersed liquid crystal layer 4 is used.
Although the temperature sensor is arranged so that the temperature of 01 can be directly monitored, a signal correlating with the temperature of the polymer dispersed liquid crystal layer 401 may be detected and controlled based on this.

According to this display device, the temperature of the liquid crystal panel 301-G is constantly monitored and the display state is optimized based on the temperature signal (TS). However, instead of disposing a temperature sensor or the like, Compensation data may be set in advance such that the video signals (V _SR ), (V _SG ), and (V _SB ) gradually decrease at predetermined time intervals.

In the display device described above, the temperature sensor is arranged above the incident side display portion, but the position may be, for example, below or on the left and right as long as the temperature can be measured accurately. Further, the temperature sensor may be arranged in close contact with the liquid crystal module, separated from the liquid crystal module, or arranged inside the liquid crystal module. Further, it may be arranged on the light emission side.

As described above, it is desirable that the light-collecting-side diaphragm and the projection-side diaphragm have a converging angle. If they do not match, the performance will be degraded as shown below. That is, when the light-collecting angle of the light-source side diaphragm is larger than that of the projecting-side diaphragm, the maximum brightness is the same as when they match, but the brightness during black display increases. Therefore, the contrast is lowered. Also, when the converging angle of the diaphragm on the light source side is smaller than the converging angle of the diaphragm on the projection side, the maximum brightness is the same as when it is the same, but the brightness during black display increases. Therefore, the contrast is lowered. Since the brightness during black display increases almost in proportion to the area of the diaphragm, the contrast also decreases in proportion to the area of the diaphragm.

The area of the diaphragm when the converging angle of the diaphragm on the light source side and the converging angle of the diaphragm on the projection side are completely equal to each other is S ₀ ,
If the area of the diaphragm with a large light collection angle is S ₀ + ΔS, the contrast r ′ when the light collection angles do not match is represented by the following formula, where r is the contrast when the light collection angles match. .

R ′ = r {S ₀ / (S ₀ + ΔS)} According to the experiments conducted by the present inventors, the degree of contrast is about 2 /
This is the case when it drops to 3. The procedure of this experiment will be described below.

With the contrast of the display screen being constant, 10
The movie film is shown for one minute, and then the contrast ratio is changed, and it is shown for five minutes. Then, an inquiry is made as to whether or not the change in contrast is recognized as the deterioration of the image quality, and the threshold value recognized as the deterioration is obtained.

As shown in FIG. 34, the initial values of the contrast threshold values are 200: 1, 100: 1, 50: 1, 2
Although the experiment was conducted with 0: 1, all the experiment results of 100: 1 or less started to be recognized as the deterioration of the image quality at about 85% of the initial value, and at about 65%, it was recognized as the deterioration of the image quality for almost all the samples. . Therefore, it is necessary to control the diaphragm with such an accuracy that the contrast ratio is suppressed to 40% or less with respect to the display of the same brightness.

That is, it is necessary to control the solid angle within a range of about ± 30%. For example, or in the case of using a circular diaphragm, with respect to the apex angle θ of the cone in the conical light flux,
It is necessary to control to about ± 0.15θ. For example, when the converging angle of the diaphragm changes to θ = 3 to 10 degrees, the accuracy of the converging angle of the diaphragm needs to be controlled within ± 0.5 to 1.5 degrees.

Next, the squeeze adjustment margin for the screen illuminance (unit looks) will be described.

When the screen illuminance (unit looks) due to external light is high, the change in contrast with respect to the angle of the diaphragm becomes slower than in the case without external light. Therefore, the required control accuracy may be lower as the outside light is larger.

The magnitude of the contrast in the optimized case is, as shown in FIG. 5, almost half of the original contrast without the influence of external light. For example, when the brightness of the room is 0 lux, the optimum contrast is 50 corresponding to the state of the diaphragm having the contrast of 100, and the contrast corresponding to the diaphragm having the contrast ratio of 30 is about 15. .

Therefore, in the state in which the aperture angle of the diaphragm is optimized with respect to the outside light, the brightness of the screen due to the original black display and the brightness of the screen due to the influence of the outside light are almost the same. It is considered to be the degree.

At this time, if an error occurs in the control of the converging angle and deviates from the optimum value, the contrast is r ′ = r
{(S _ext + S ₀ ) / (S _ext S ₀ + ΔS) = r {S ₀ / (S ₀ + ΔS / 2)} where S _ext is the brightness of external light and is the black display of the projection display device. It is a value converted into the converging angle of the diaphragm, and since the original black display of the projection type display device and the brightness of external light have the same influence, S _ext = S ₀ .

As can be seen from the above equation, the margin is doubled. However, considering that there is a margin relating to the matching of the two diaphragms shown above, the error of the converging angle of the diaphragm to be controlled with respect to the external condition is 1/2. Therefore, the margin in this case also needs to be related to the coincidence of the light collecting angles of the both.

Next, FIG. 41 shows the fifth embodiment of the present invention.
Will be described with reference to. The basic configuration of the display device according to the fifth aspect is the same as that shown in FIG.

The projection type liquid crystal display device 100 of this aspect is
As shown in FIG. 41, each liquid crystal panel 201-R, 201
-G, 201-B respectively video signals (VSR), (V
SG), (VSB) drive voltage supply circuit 74 for supplying
1 and a polarity inverting / non-inverting amplifier 751.

As shown in FIG. 42, the drive voltage supply circuit 731 converts the input brightness signal (BS) into a digital signal by the analog / digital converter 743, and converts the digitalized brightness signal (BS) into a ROM. The gamma-corrected digital luminance signal that has been gamma-corrected by the configured gamma-correction circuit 744 is supplied to one input terminal of the adder 745. Further, based on the environmental brightness signal (ES) from the optical sensor 711, the T configuring the liquid crystal panel 201-G from the optical leak compensation circuit 746 including the ROM.
Compensation data for correcting the potential drop due to the light leakage current (Ioff) of the FT 241 is supplied to the other input terminal of the adder 745, and the addition output of the digital luminance signal and the compensation data is supplied from the adder 745 to a digital / analog converter. 7
Output to 47. Then, the analog signal from the digital / analog converter 747 is converted to the polarity inverting / non-inverting amplifier 74.
It is output to 1.

The polarity inversion / non-inversion amplifier 741 amplifies the analog signal to a signal level required for the liquid crystal panel 201-G, and inverts the polarity with respect to the reference potential at a predetermined cycle such as each field period or each scanning period. Video signal (V
SG) and supplies it to the liquid crystal panel 201-G.

Further, other liquid crystal panels 201-R, 201
Similarly, −B also applies to the environmental luminance signal (E
Video signals (VSR), (VSB) corrected based on S)
Are supplied to the liquid crystal panels 201-R and 201-B. That is, in this embodiment, the first is such that the converging angles (Ω ₁ ) and (Ω ₂ ) increase as the brightness on the screen increases.
The aperture diameters (D ₁ ) and (D ₂ ) of the diaphragm means 151 and the second diaphragm means 503 are controlled by the diaphragm control means 721, and accordingly, the respective liquid crystal panels 201-R and 20-R.
Video signal (VSR) supplied to 1-G, 201-B,
The drive voltage supply circuit 731 controls so that (VSG) and (VSB) are also increased.

The operation of the projection type liquid crystal display device 700 configured as described above will be briefly described.

First, the illuminance on the screen (unit: cd /
m ² ) is detected by the optical sensor 711,
The aperture diameters (D ₁ ) and (D ₂ ) of the first diaphragm means 151 and the second diaphragm means 503 are determined by the diaphragm control means 721 on the basis of the environmental brightness signal (ES). That is, as the brightness on the screen increases, the opening diameters (D ₁ ) and (D ₂ ) of the first diaphragm means 151 and the second diaphragm means 503 are increased.

When the drive voltage supply circuit 731 does not optimize the video signals (VSR), (VSG), (VSB), for example, when the illuminance on the screen is dark such as 30 lux, the light collection angle (Ω ₁ ), (Ω ₂ ) is 1.1 × 10 ^-3
set to sr and a contrast ratio of 70: 1 is achieved. Conversely, when the illuminance on the screen is as bright as 200 lux, the converging angles (Ω ₁ ) and (Ω ₂ ) are 8.6 × 10.
^-3 sr, the collection angle (Ω ₁ ), (Ω ₂ ) 1.1 ×
The peak luminous flux during white display when set to 10 ^-3 sr is 1
A peak luminous flux as high as 75 lm is achieved as compared with 8 lm.

Further, in this embodiment, based on the environmental brightness signal (ES) from the optical sensor 711, when the illuminance on the screen is 200 lux, the illuminance on the screen is 30 lux.
About 10% of each video signal (VSR), (VS
G) and (VSB) are increased by the drive voltage supply circuit 741.

In this way, the video signals (VSR), (VS
G) and (VSB) are optimized, the video signal (VS
R), (VSG), and (VSB) are not adjusted, the contrast ratio and the display brightness are further 10% from the above values when the illuminance on the screen is 2001x.
I was able to improve the degree.

As described above, according to this embodiment, the deterioration of the contrast ratio and the display brightness due to the light leakage current (I _off ) of the TFT 241 due to the increase of the converging angle (Ω ₁ ) is prevented, which is more preferable. It is possible to secure excellent display quality.

In this embodiment, the opening diameter (D ₂ ) of the _second diaphragm means 503 is changed to the opening diameter (D ₂ ) of the first diaphragm means 151.
_Although it was moved so as to have the same value as ₁ ), it does not necessarily have to match.

Also, in this embodiment, each liquid crystal panel 201 is
-R, 201-G, 201-B for each light source light collection angle (Ω
_{It is also possible} to provide a diaphragm means for controlling ₁ ) and individually control the light collection angle (Ω ₁ ) of the light source for each color. Also,
In this aspect, the diaphragm control means 721 controls the converging angles (Ω ₁ ) and (Ω ₂ ) of the first diaphragm means 351 and the second diaphragm means 503 according to the environmental brightness signal (ES). However, based on the brightness signal (BS) input to the drive voltage supply circuit 741, the first diaphragm unit 35
The first and second diaphragm means 503 may be controlled, or a combination of these may be used.
For example, based on the difference between the time average intensity of the input brightness signal (BS) and the blanking level (black level) of the brightness signal, if the difference is small, the converging angles (Ω ₁ ) and (Ω ₂ ) are set. When the difference is small and the difference is large, by controlling the converging angles (Ω ₁ ) and (Ω ₂ ) to be large, a good display image can be secured without depending on the display brightness of the display image.

In this mode, the optical sensor 711 monitors the brightness on the screen, but may monitor the environmental illuminance (unit lux).

In this embodiment, the projection type display device 100 of the three-plate type has been described as an example. However, the liquid crystal panel itself includes a color filter composed of color portions of at least three primary colors arranged in a stripe shape, a mosaic shape or a delta arrangement. Prepare,
It goes without saying that the projection type display device may be a single plate type.

By the way, each liquid crystal panel 201-R, 20
Microlens array substrate 411 on 1-G and 201-B
By combining and using
By increasing the effective aperture ratios of -R, 201-G, and 201-B, it is possible to improve both the effective contrast ratio on the screen and the display brightness when displaying in a bright environment. The liquid crystal panel 201-G will be described below as an example with reference to FIG. This liquid crystal panel 20-G is configured by adhering a microlens array substrate 411 on the main surface of a counter substrate 311 that constitutes the liquid crystal panel 201-G via an adhesive layer 410. The microlens array substrate 411 includes a condenser lens 41 corresponding to each display pixel.
It is composed of three groups, and the focal position of the condenser lens 413 is set so as to exist on the glass substrate 210 which constitutes the array substrate 211.

As described above, each liquid crystal panel 201-R, 2
If 01-G and 201-B are configured, the light shielding amount 3
Since light that has been blocked by 13 and not being effectively used can also be used, the liquid crystal panels 201-R, 201-G, and 20 can be used.
The effective aperture ratio of 1-B can be made large, a sufficient peak luminous flux can be obtained even if the converging angles (Ω ₁ ) and (Ω ₂ ) are narrowed, and the decrease in display brightness is reduced.

When the microlens array substrate 411 is provided on the light incident side of the liquid crystal panel 201-G as in this embodiment, the aperture diameter (D ₂ ) of the _second diaphragm means 503 is set to the first.
It is preferable to control within a range larger than the opening diameter (D ₁ ) of the diaphragm means 151. This is because the light once condensed by the microlens is diverged thereafter.

That is, when the microlens array substrate 411 is arranged only on the incident side as in the above-described embodiment, the light focused by the microlens array substrate 411 near the light shielding layer 313 of the counter substrate 311 diverges thereafter. Therefore, the light utilization efficiency may decrease. Therefore, when using the microlens array substrate 411, it is important to select the focal position of each condenser lens 413 of the microlens array substrate 411. That is, it is necessary to select the focal position so that the light source light, which is spread after being converged by each condenser lens 413, is sufficiently contained in the projection lens 505. In particular, if miniaturization of the projection lens 505 is achieved, it is preferable to use a lens having a long focal point of each condenser lens 413 of the microlens array substrate 411 and a small numerical aperture. However, the effect of the microlens array substrate 411 decreases as the focus position of each condenser lens 413 moves away from the light incident side, and each liquid crystal panel 201-R, 201-G, 201-B.
The degree of increase in the effective aperture ratio of is small. Therefore, the focal position of each condenser lens 413 of the microlens array substrate 411 is preferably set inside the polymer-dispersed liquid crystal layer 401 or slightly outside the substrate 210 on the emission side.

In the above-described embodiment, a servo motor is built in as the first diaphragm means 351 and the second diaphragm means 503 shown in FIG. 41, and the opening diameters (D ₁ ) and (D ₁ ) of the circular openings are formed by the servo motor. ₂ ) was changed, but
The shape of this opening may be quadrangular or elliptical. Further, the structure may be such that the light shielding plate that shields the upper and lower portions of the opening or the right and left portions is movable by the servo motor.

Further, in this embodiment, the aperture diameters (D ₁ ) and (D ₂ ) of the first diaphragm means 351 and the second diaphragm means 503 are controlled by the first diaphragm control means 721, respectively, and the light collection angle is controlled. Although (Ω ₁ ) and (Ω ₂ ) are controlled, by moving the first diaphragm means 351 and the second diaphragm means 503 along the optical axis of the light source 311, the effective aperture diameter (D
₁ ) and (D ₂ ) may be controlled to control the converging angles (Ω ₁ ) and (Ω ₂ ).

Further, as the liquid crystal panel of the above-mentioned mode, the active matrix type liquid crystal panel in which the switch element composed of the TFT is provided for each display pixel is described as an example, but the TFT is a polycrystalline silicon film or a single crystal. You may comprise mainly a silicon film.

Next, the sixth aspect of the present invention will be described.

This mode relates to a simple projection type display device. In order to simplify the operation, after the power is input,
The aperture setting is automatically optimized according to the ambient illuminance. An example of this simple projection type display device is shown in FIG. In this display device, the size of the screen and the gain are assumed in advance, and the projected light flux in the absence of the projected light is measured.
The brightness of the lens is directly measured so that the optimum angle of the diaphragm can be quickly determined. The converging angle of the diaphragm is automatically determined when the power of the projection type display device is turned on.

In this display device, since the brightness of the screen is measured without the projection light from the projection type display device,
An optical path blocking device 901 is provided. This is arranged on the exit side of the panel as shown in FIG. 35, and is controlled by the optical path blocking device control circuit 900 so that the light from the light source can be switched between blocking and non-blocking at the entrance of the projection lens.

FIG. 36 is a flowchart showing a process for automatically determining the light collecting angle after the power is turned on in the display device shown in FIG. It takes a few minutes for the metal halide lamp, which is the light source, to completely light up. In the display device shown in FIG. 35, since the optical path is blocked by the optical path blocking device and the screen brightness is measured according to the indoor brightness, it is not necessary to wait until the lamp brightness settles to a steady state. Therefore, first, the lamp lighting process (application of high voltage and start of discharge) is performed, but the brightness of the screen is measured and the converging angle of the diaphragm is determined without waiting for the lamp to rise.

FIG. 37 shows another example of a simple projection type display device. In this display device, in order to simplify the operation,
The projection lens is provided with an encoder 910 for detecting the focal position of the projection lens, and the output of the encoder 910 can be detected from the CPU side by the projection distance detection circuit 920. Therefore, the projection distance detection circuit 920 can detect the screen size.

In the display device shown in FIG. 37, the projection coefficient q in the following equation is automatically calculated by assuming the screen gain to be 1.5. Therefore, only L ₀ is unknown, and by measuring the screen luminance L in the state of I = 0 by the optical path blocker, the indoor brightness L
You can ask for ₀ .

L = qI + L ₀ FIG. 38 is a diagram showing the flow chart of the process for automatically determining the converging angle in the display device shown in FIG.
In this display device, since the screen size is detected by the focal position of the projection lens, the aperture is optimized by pressing the aperture optimization switch after focusing the projected image. Although the front projection type display device using the reflection type screen has been described above, the present invention is not limited to this, and is also applied to a rear projection type display device as shown in FIGS. 39 and 40. It is possible.

In the rear projection type display device shown in FIGS. 39 and 40, the projection light from the optical system 950 is reflected by the first mirror 960 and the second mirror 970,
It is projected on the transmission screen 980. Further, an optical sensor for measuring the screen brightness due to external light is arranged. In the above-mentioned front projection type display device, the optical sensor is arranged on the side portion of the projection lens, and is arranged so as to measure the intensity of the reflected light of the screen in the direction of the screen. In the display device of FIG. 39, as shown in FIGS. 39 and 40, the sensor A and the sensor B are provided at the corners of the screen.
You can attach it like this and measure the illuminance. In the case of the rear projection type, since the screen characteristics are often predetermined, the screen brightness can be estimated from the illuminance.

Further, like the sensor C, it can be arranged inside the screen and the brightness of the external light passing through the screen can be measured. Of course, these sensors need to be arranged so that light from the projection optics does not enter so that only the effects of pure external light can be measured.

Further, in the case of the rear projection type, since the projection coefficient q in the above equation is predetermined, the optimum converging angle of the diaphragm can be determined only by measuring the influence L _{0 of} external light. Is possible.

The display quality of the projection type display device changes depending on the brightness of the screen black label depending on the brightness of various environments such as the place of projection or the time zone. In the case of the front projection type display device, the correction based on the display quality due to the environmental brightness may be a considerable distance between the projection type display device and the screen, so that the projection type display device is installed. The ambient brightness and the brightness around the screen are different. Further, in reality, the illumination illuminance or the illumination brightness determined by the screen surface which is set up substantially vertically and the screen gain contribute to the display quality.

Therefore, since the display quality is greatly affected by the environmental lighting condition around the screen and the external light from the window of the room, the display quality of the projection display device is controlled by the screen surface depending on the environmental brightness. It is important to monitor and control the brightness directly. In meetings, etc., the ambient brightness of the entire room can be arbitrarily controlled according to the usage conditions, the partial ambient brightness can be controlled, or the screen can be adjusted at the adjustment stage and the final operation stage. Since the ambient brightness around the screen changes, it is desirable to adjust the display quality according to the screen surface brightness at the assembly stage.

Therefore, it is important to display an image of higher quality by equipping the projection type display device with an optical sensor for monitoring the black display level brightness and contrast of the display device on the screen surface. Is.

In the above, an example in which a polymer dispersion type or fine particle dispersion type dispersion type liquid crystal display element is used as a liquid crystal panel has been described, but the present invention is particularly applicable to the case where the dispersion type liquid crystal display element is used. Although suitable, other than that,
It is also applicable to various liquid crystal elements such as a TN type liquid crystal element, an STN type liquid crystal element, and a liquid crystal diffraction grating by an oblique electric field.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a conventional projection display device.

FIG. 2 is a diagram showing an example of a collimator light source that obtains parallel rays from a lamp.

FIG. 3 is a diagram showing an incident light ray of the condenser lens shown in FIG.

FIG. 4 is a diagram showing a relationship between an angular distribution of a light beam incident on the modulation element shown in FIG. 2 and an angular distribution of a light beam emitted from the modulation element.

FIG. 5 shows the relationship between the intensity of the luminous flux emitted from the modulation element and the contrast of the image measured corresponding to the angle of collection when the image is displayed on a screen placed in an illuminated environment. The graph showing.

FIG. 6 is a diagram showing the configuration of a projection display device for explaining the basic concept of the present invention.

FIG. 7 is a diagram showing a configuration of a projection type display device according to a first aspect of the present invention.

FIG. 8 is a diagram showing the shape of the aperture of the diaphragm and various aperture diameters of the diaphragm.

9 is a flowchart for explaining the operation of the display device shown in FIG.

FIG. 10 is a flowchart showing the processing operation shown in FIG. 9 in more detail.

FIG. 11 is a flowchart for explaining the operation of the projection type display device of another example according to the first aspect of the present invention.

FIG. 12 is a diagram showing a configuration of a projection type display device according to a second aspect of the present invention.

FIG. 13 is a diagram showing a relationship between two input signals of the control circuit shown in FIG. 12 and a focusing angle of a diaphragm.

FIG. 14 is an average video level (APL) in FIG.
FIG. 3 is a circuit diagram specifically showing a detection circuit.

FIG. 15 is the collector input of the transistor of the circuit of FIG. Buffer transistor emitter output. 7A and 7B are diagrams illustrating an emitter output of a buffer transistor.

FIG. 16 is a circuit diagram showing another example of an APL detection circuit.

17 is a diagram showing collector outputs of transistors and emitter outputs of other transistors in the circuit of FIG.

FIG. 18 is a graph showing the relationship between the collection angle and display characteristics.

FIG. 19 is a graph showing effective display characteristics in a bright environment.

FIG. 20 is a graph showing drive voltage-transmitted light intensity characteristics of a modulator in a display device according to a third aspect of the present invention.

FIG. 21 is a graph for explaining that the transmittance of the modulation element in the display device according to the third aspect of the present invention deviates from a desired value due to a change in the converging angle of the diaphragm.

FIG. 22 is a diagram showing a distribution of an incident light beam and a distribution of an outgoing light beam with respect to a modulator.

FIG. 23 is a diagram showing a light scattering property of a modulator.

FIG. 24 is a diagram showing how the effective portion of the emitted light flux shown in FIG. 23, which is involved in display, changes depending on the converging angle.

FIG. 25 is a diagram showing a configuration of a projection type display device according to a third aspect of the present invention.

FIG. 26 is a diagram showing the configuration of the gamma correction circuit shown in FIG. 25 in more detail.

FIG. 27 is a graph showing the temperature dependence of the light modulation element.

FIG. 28 is a diagram showing a configuration of a projection type liquid crystal display device according to a fourth aspect of the present invention.

29 is a plan view showing the structure of the modulation element in the display device of FIG. 28. FIG.

30 is a cross-sectional view showing the structure of the modulation element in the display device of FIG. 28.

FIG. 31 is a diagram showing the arrangement of temperature sensors in the display device shown in FIG. 28.

FIG. 32 is a diagram showing a specific circuit of a temperature sensor.

33 is a diagram showing a drive voltage supply circuit in the display device shown in FIG. 28.

FIG. 34 is a graph showing the relationship between the rate of change in contrast and the recognition probability.

FIG. 35 is a diagram showing a configuration of a simple projection display device according to a sixth aspect of the present invention.

FIG. 36 shows the display device shown in FIG. 35. Flowchart of processing for automatically determining the collection angle after power is turned on.
FIG.

FIG. 37 is a diagram showing another example of a simple projection type display device.

38 is a view showing a flowchart of processing for automatically determining the light collecting angle in the display device shown in FIG.

FIG. 39 is a perspective view showing a rear projection type display device.

FIG. 40 is a cross-sectional view showing a rear projection type display device.

FIG. 41 is a diagram showing a configuration of a projection type liquid crystal display device according to a fifth aspect of the present invention.

42 is a diagram showing a drive voltage supply circuit in the display device shown in FIG. 41.

43 is a cross-sectional view showing the configuration of the modulation element in the display device of FIG. 41.

[Explanation of symbols]

101 ... spheroidal mirror ... 102 light source lamp, 1
03 ... Condenser lens, 104 ... Electric diaphragm, 107 ...
Drive circuit, 108 ... Scattering type modulation element, 109 ... Field lens, 110 ... Projection lens, 111 ... Electric diaphragm, 1
20 ... Control circuit, 121 ... Decoder, 140 ... Luminance signal smoothing circuit, 140B ... RC integrating circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 6-190273 (32) Priority Date Hei 6 (1994) August 12 (33) Country of priority claim Japan (JP) (31) Priority Claim number Japanese patent application No. 6-190350 (32) Priority date Hei 6 (1994) August 12 (33) Priority claiming country Japan (JP) (72) Inventor Shoji Murakami 1-9 Harara-cho, Fukaya-shi, Saitama No. 2 inside the Toshiba Fukaya Plant (72) Inventor Tsutomu Sakamoto 1-9-2 Harara-cho, Fukaya-shi, Saitama Inside the Toshiba Fukaya Plant (72) Inventor Kazuki Hira 33 Isogo-cho, Isogo-ku, Yokohama, Kanagawa Prefecture Address Stock Production Company, Toshiba Industrial Technology Research Institute (72) Inventor Hiroshi Saito 1-9-2, Harara-cho, Fukaya-shi, Saitama Inside Toshiba Corporation Fukaya Plant

Claims (8)

[Claims] 1. A light source, a modulation element for optically modulating light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source arranged between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. Second aperture means having an opening, and an optical sensor for detecting display brightness on the display screen.
And a diaphragm control unit that controls the size of the opening of at least one of the first and second diaphragm units based on a display luminance signal from the optical sensor. 2. A light source, a modulation element for optically modulating light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source arranged between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. Second aperture means having an opening, and an optical sensor for detecting display brightness on the display screen.
And controlling the size of the aperture of at least one of the first and second diaphragm means based on a video luminance signal sent from the modulator driving means to the modulator and a display luminance signal from the optical sensor. A display device comprising: 3. A light source, a modulation element for optically modulating light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source arranged between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. Second aperture means having an aperture, aperture control means for controlling the size of the aperture of at least one of the first and second aperture means, and the first and second aperture control means controlled by the aperture control means. Aperture means Display device comprising a modulation element drive means for sending a control video signal based on the size of the at least one opening to the modulation element. 4. A light source, a modulation element for optically modulating the light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source arranged between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. A second aperture means having an opening, a temperature sensor arranged in the vicinity of the modulation element, and a video signal sent from the driving means to the modulation element based on a temperature signal from the temperature sensor. control Display apparatus comprising a video signal control unit that. 5. A light source, a modulation element for optically modulating the light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source disposed between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. Second aperture means having an aperture, aperture control means for controlling the size of the aperture of at least one of the first and second aperture means, and the first and second aperture control means controlled by the aperture control means. Aperture means It caused to correspond to the size of at least one opening, the driving voltage of the modulation device - display device including a compensating means for compensating for changes in the modulated light intensity characteristic. 6. A light source, a modulation element for optically modulating the light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source disposed between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. Second aperture means having an aperture, aperture control means for controlling the size of the aperture of at least one of the first and second aperture means, and light intensity setting means for setting at least two light intensities I, these An optical sensor for detecting the display brightness L on the screen corresponding to the light intensity I, and the light intensity I and the detected display brightness L are expressed by the formula L = qI +.
L ₀ (L ₀ is the environmental brightness on the display screen based on the light from the environment in which the display device is placed) and the environmental analysis means for calculating the projection coefficient q and the environmental brightness L ₀ ; The contrast on the display screen is calculated from the above equations for the projection coefficient q and the environmental brightness L ₀ ,
A means for storing data indicating the size of the aperture of at least one of the first and second diaphragm means that maximizes the contrast, and the first and the first and the maximum storage means for maximizing the contrast. A display device comprising: a processing unit that specifies a size of at least one opening of the second diaphragm unit and determines the size as an optimum value. 7. A light source, a modulation element for optically modulating the light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source disposed between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. Second aperture means having an opening, an optical path blocking means for blocking the light emitted from the modulation element, and the screen in a state where the light emitted from the modulation element is blocked by the optical path blocking means. An optical sensor for detecting the above display brightness, and an aperture control means for controlling the size of the opening of at least one of the first and second aperture means based on the display luminance signal from the optical sensor. Display device. 8. A light source, a modulation element for optically modulating the light emitted from the light source, a modulation element driving means for driving the modulation element, and a light source disposed between the light source and the modulation element. From the modulator, a first aperture means having an aperture whose size is variable, which limits the light flux entering the modulator, a display screen on which the light emitted from the modulator is projected, and a display screen emitted from the modulator. A projection optical system for projecting the reflected light onto a display screen, and a light flux which is arranged between the modulation element and the projection optical system and which limits a light flux incident on the projection optical system from the modulation element, and its size is variable. A second aperture means having an opening, a means for determining a size of the display screen by detecting a focal length of a projection lens of the projection optical system, and thereby obtaining a projection coefficient, and the modulation element. An optical path blocking means for blocking light emitted from the light source, an optical sensor for detecting display brightness on the screen in a state where the light emitted from the modulator is blocked by the optical path blocking means, and the projection Based on the coefficient and the display brightness on the screen,
A display device comprising: an aperture control unit that controls the size of the opening of at least one of the first and second aperture units.