JP2009080383A - Projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type display device capable of correcting luminance balance even when luminance balance between a plurality of colors is lost. <P>SOLUTION: A photosensor element 40 formed in a dummy pixel region 10d of an element substrate 10 in liquid crystal light valves 100 (R), (G), (B) of respective colors used for the projection type display device receives color light from a light source part, which is made incident from a counter substrate side. Thereby, an incident light quantity balance of each color light can be monitored based on the light receiving result in the photosensor element 40 and luminance balance of the liquid crystal light valves 100 (R), (G), (B) can be suitably held if a driving condition of the liquid crystal light valves 100 (R), (G), (B) is controlled based on the monitoring result. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projection display device using a liquid crystal light valve as a light valve.

The projection display device includes a light source unit that emits red (R), green (G), and blue (B) color light, a plurality of light valves that light-modulate each color light emitted from the light source unit, and a plurality of lights. It has a synthesis optical system that synthesizes and emits the modulated light emitted from the bulb, and a projection optical system that projects the light emitted from the synthesis projection system. The light source unit employs a configuration including a white light source and a color separation optical system that separates white light emitted from the white light source into each color light. In addition, the light valve is a light-transmitting element disposed on the element substrate having a pixel electrode and a pixel switching element on each of a plurality of display pixels arranged in the image display area and facing the element substrate on the side where the color light is incident. A liquid crystal light valve having a counter substrate and a liquid crystal held between the counter substrate and the element substrate is used (see Patent Document 1).
JP 2006-78625 A

In the projection display device having such a configuration, in order to display a high-quality color image, it is necessary to optimally maintain the luminance balance of red (R), green (G), and blue (B). Normally, in consideration of the visibility of colored light, the set luminances of red (R), green (G), and blue (B) in FIG. 5A are indicated by solid lines LR0, LG0, and LB0, respectively. Is the following relationship: Green (G)> Blue (B)> Red (R)
Is set to

Here, in the projection type display device, the white light spectrum may change due to deterioration of the white light source over time, and in such a case, the above-described luminance balance may be lost. Further, the deterioration of the liquid crystal light valve over time may differ depending on the corresponding color, and in this case, the above relationship is broken. For example, a liquid crystal light valve corresponding to a short wavelength blue (B) is more likely to deteriorate than a liquid crystal light valve corresponding to red (R) or green (G). As shown by the dotted line LB1 in the blue (B) luminance, the luminance has the following relationship: green (G)> red (R)> blue (B)
As a result, the quality of the color image is degraded.

  However, in the conventional projection display device, no countermeasure is taken against the loss of the luminance balance due to the deterioration of the liquid crystal light valve over time, so that the liquid crystal light valve corresponding to red (R) or green (G), for example. Even if the liquid crystal light valve is not deteriorated, there is a problem in that the quality of the color image is greatly lowered when the liquid crystal light valve corresponding to blue (B) is deteriorated.

  In view of the above problems, an object of the present invention is to provide a projection display device capable of correcting a luminance balance even when the luminance balance among a plurality of colors is lost.

  In order to solve the above-described problem, in the present invention, a light source unit that emits a plurality of types of color light, a plurality of liquid crystal light valves that light-modulate each of the plurality of color lights emitted from the light source unit, and the plurality of liquid crystals In the projection type display device having a synthesis optical system that synthesizes and emits the modulated light emitted from the light valve, and a projection optical system that projects the light emitted from the synthesis projection system, the plurality of liquid crystal light valves include: An element substrate provided with a pixel electrode and a pixel switching element for each of a plurality of display pixels arranged in the image display area, and a light-transmitting counter disposed opposite to the element substrate on the color light incident side An optical sensor having a substrate and a liquid crystal held between the counter substrate and the element substrate, the element substrate being capable of receiving light incident from the counter substrate side outside the image display region Element shape Is, based on the reception result at the optical sensor element, the luminance balance of the plurality of liquid crystal light valve, characterized in that it is corrected.

  In the present invention, in each of the plurality of liquid crystal light valves, the light sensor element formed on the element substrate receives light from the light source unit incident from the counter substrate side. If the received light results are compared, it is possible to monitor the light intensity balance of each color light incident on each of the plurality of liquid crystal light valves. For this reason, if the adjustment is made to increase the gradation in the liquid crystal light valve corresponding to the color light whose incident light amount has decreased, or the adjustment to reduce the gradation in the liquid crystal light valve corresponding to the color light other than the color light whose incident light amount has decreased, each color light It is possible to correct the luminance balance in the liquid crystal light valve corresponding to. Therefore, a high-quality color image can be displayed even when the balance of the amount of incident light is lost.

  In the present invention, a pixel electrode and a pixel switching element are provided outside the image display area in the element substrate and inside a sealing material that partitions the liquid crystal holding area between the element substrate and the counter substrate. A dummy pixel region in which dummy pixels that do not directly contribute to display are formed, and the photosensor element is the dummy pixel region and is formed at a position overlapping the pixel electrode on the lower layer side of the pixel electrode It is preferable that If comprised in this way, the optical sensor element can detect external light in the position close | similar to an image display area.

  In the present invention, among the display pixel and the dummy pixel, at least the dummy pixel is formed in a stripe shape having a smaller pitch than the wavelength of incident light and forms the pixel electrode, and the pixel It is preferable that any one of the wire grid polarizers formed in a stripe shape having a smaller pitch than the wavelength of light incident between the electrode and the optical sensor element is provided. With this configuration, the light reception result of the optical sensor element reflects the degree of deterioration of the liquid crystal. Based on the light reception result, the balance of the incident light amount in each color light is lost, and the liquid crystal is deteriorated. The luminance balance can be corrected including all the effects of the degree.

  In the present invention, the correction of the luminance balance is performed, for example, by adjusting a signal level applied to the pixel electrode. Such a configuration can correct the luminance balance even when the light source unit includes a white light source and a color separation optical system that separates the white light emitted from the white light source into each color light.

  In addition, when the light source unit includes a light emitting element that emits light of each color, the luminance balance may be corrected by adjusting the driving condition for the light emitting element based on the light reception result of the light sensor element. Good.

  The present invention will be described below with reference to the drawings. In the drawings to be referred to in the following description, the scales are different for each layer and each member so that each layer and each member have a size that can be recognized on the drawing.

[Configuration example of a projection display device]
FIG. 1 is a schematic configuration diagram of a projection display device (liquid crystal projector) to which the present invention is applied. A projection type display device 110 shown in FIG. 1 is a projection type liquid crystal projector that irradiates light on a screen 111 (projected surface) provided on the viewer side and observes the light reflected by the screen 111. The projection display device 110 includes a light source unit 150 including a light source 112 and dichroic mirrors 113 and 114, liquid crystal light valves 100 (R), (G), and (B), a projection optical system 118, and a cross dichroic prism. 119 (color synthesis optical system) and a relay system 120 are provided.

  In the light source unit 150, the light source 112 is configured by an ultrahigh pressure mercury lamp that supplies light including red light, green light, and blue light. The dichroic mirror 113 is configured to transmit red light from the light source 112 and reflect green light and blue light. The dichroic mirror 114 is configured to transmit blue light and reflect green light among green light and blue light reflected by the dichroic mirror 113. Thus, the dichroic mirrors 113 and 114 constitute a color separation optical system that separates the light emitted from the light source 112 into red light, green light, and blue light.

  Here, between the dichroic mirror 113 and the light source 112, an integrator 121 and a polarization conversion element 122 are arranged in order from the light source 112. The integrator 121 is configured to make the illuminance distribution of the light emitted from the light source 112 uniform. Further, the polarization conversion element 122 is configured to change the light from the light source 112 into polarized light having a specific vibration direction such as s-polarized light.

  The liquid crystal light valve 100 (R) is a transmissive liquid crystal device that modulates red light that has been transmitted through the dichroic mirror 113 and reflected by the reflection mirror 123 in accordance with an image signal. The liquid crystal light valve 100 (R) includes a λ / 2 retardation plate 115a, a first polarizing plate 115b, a liquid crystal panel 101 (R), and a second polarizing plate 115d. Here, the red light incident on the liquid crystal light valve 100 (R) remains s-polarized light because the polarization of the light does not change even if it passes through the dichroic mirror 113. The λ / 2 phase difference plate 115a is an optical element that converts s-polarized light incident on the liquid crystal light valve 100 (R) into p-polarized light. The first polarizing plate 115b is a polarizing plate that blocks s-polarized light and transmits p-polarized light. The liquid crystal panel 101 (R) is configured to convert p-polarized light into s-polarized light (circularly polarized light or elliptically polarized light in the case of halftone) by modulation according to the image signal. Furthermore, the second polarizing plate 115d is a polarizing plate that blocks p-polarized light and transmits s-polarized light. Accordingly, the liquid crystal light valve 100 (R) is configured to modulate red light in accordance with an image signal and to emit the modulated red light toward the cross dichroic prism 119. The λ / 2 phase difference plate 115a and the first polarizing plate 115b are disposed in contact with a light-transmitting glass plate 115e that does not convert polarized light, and the λ / 2 phase difference plate 115a and the first polarizing plate 115b. It is possible to avoid distortion of 115b due to heat generation.

  The liquid crystal light valve 100 (G) is a transmissive liquid crystal device that modulates green light reflected by the dichroic mirror 114 after being reflected by the dichroic mirror 113 in accordance with an image signal. The liquid crystal light valve 100 (G) includes a first polarizing plate 116b, a liquid crystal panel 101 (G), and a second polarizing plate 116d, like the liquid crystal light valve 100 (R). The green light incident on the liquid crystal light valve 100 (G) is s-polarized light that is reflected by the dichroic mirrors 113 and 114 and incident. The first polarizing plate 116b is a polarizing plate that blocks p-polarized light and transmits s-polarized light. The liquid crystal panel 101 (G) is configured to convert s-polarized light into p-polarized light (circularly polarized light or elliptically polarized light in the case of halftone) by modulation according to the image signal. The second polarizing plate 116d is a polarizing plate that blocks s-polarized light and transmits p-polarized light. Accordingly, the liquid crystal light valve 100 (G) is configured to modulate green light in accordance with an image signal and to emit the modulated green light toward the cross dichroic prism 119.

  The liquid crystal light valve 100 (B) is a transmissive liquid crystal device that modulates blue light reflected by the dichroic mirror 113 and transmitted through the dichroic mirror 114 and then through the relay system 120 in accordance with an image signal. The liquid crystal light valve 100 (B) is similar to the liquid crystal light valves 100 (R) and 116 in that the λ / 2 phase difference plate 117a, the first polarizing plate 117b, the liquid crystal panel 101 (B), and the second polarizing plate 117d. It has. Here, since the blue light incident on the liquid crystal light valve 100 (B) is reflected by the dichroic mirror 113 and transmitted through the dichroic mirror 114, it is reflected by two reflection mirrors 125 a and 125 b described later of the relay system 120. It is s-polarized light. The λ / 2 phase difference plate 117a is an optical element that converts s-polarized light incident on the liquid crystal light valve 100 (B) into p-polarized light. The first polarizing plate 117b is a polarizing plate that blocks s-polarized light and transmits p-polarized light. The liquid crystal panel 101 (B) is configured to convert p-polarized light into s-polarized light (circularly polarized light or elliptically polarized light in the case of halftone) by modulation according to the image signal. Furthermore, the second polarizing plate 117d is a polarizing plate that blocks p-polarized light and transmits s-polarized light. Accordingly, the liquid crystal light valve 100 (B) is configured to modulate blue light in accordance with an image signal and to emit the modulated blue light toward the cross dichroic prism 119. The λ / 2 phase difference plate 117a and the first polarizing plate 117b are arranged in contact with the glass plate 117e.

  The relay system 120 includes relay lenses 124a and 124b and reflection mirrors 125a and 125b. The relay lenses 124a and 124b are provided to prevent light loss due to a long blue light path. Here, the relay lens 124a is disposed between the dichroic mirror 114 and the reflection mirror 125a. The relay lens 124b is disposed between the reflection mirrors 125a and 125b. The reflection mirror 125a is disposed so as to reflect the blue light transmitted through the dichroic mirror 114 and emitted from the relay lens 124a toward the relay lens 124b. The reflection mirror 125b is disposed so as to reflect the blue light emitted from the relay lens 124b toward the liquid crystal light valve 100 (B).

  The cross dichroic prism 119 is a color combining optical system in which two dichroic films 119a and 119b are arranged orthogonally in an X shape. The dichroic film 119a is a film that reflects blue light and transmits green light, and the dichroic film 119b is a film that reflects red light and transmits green light. Therefore, the cross dichroic prism 119 combines the red light, the green light, and the blue light modulated by the liquid crystal light valves 100 (R), (G), and (B), respectively, and emits the light toward the projection optical system 118. Is configured to do.

  The light incident on the cross dichroic prism 119 from the liquid crystal light valves 100 (R) and (B) is s-polarized light, and the light incident on the cross dichroic prism 119 from the liquid crystal light valve 100 (G) is p-polarized light. In this way, by making the light incident on the cross dichroic prism 119 into different types of polarized light, the light incident from the liquid crystal light valves 100 (R), (G), and (B) in the cross dichroic prism 119 is effectively combined. it can. Here, in general, the dichroic films 119a and 119b are excellent in the reflection characteristics of s-polarized light. For this reason, red light and blue light reflected by the dichroic films 119a and 119b are s-polarized light, and green light transmitted through the dichroic films 119a and 119b is p-polarized light. The projection optical system 118 has a projection lens (not shown) and is configured to project the light combined by the cross dichroic prism 119 onto the screen 111.

(Configuration of liquid crystal light valve)
FIG. 2 is a block diagram showing the electrical configuration of the liquid crystal light valves 100 (R), (G), (B), etc. used in the projection display device 110 shown in FIG. Since the basic configuration of each of the liquid crystal light valves 100 (R), (G), and (B) is substantially the same, in the following description, when the corresponding color type is not relevant, the liquid crystal light valve 100 (R), (G), and (B) are simply referred to as “liquid crystal light valve 100”, and the liquid crystal panels 101 (R), (G), and (B) are simply referred to as “liquid crystal panel 101”.

  Liquid crystal light valves 100 (R), (G), and (B) shown in FIG. 2 are all-transmissive liquid crystal devices, and include a liquid crystal panel 101, an image processing circuit 202, a timing generation circuit 203, a power supply circuit 201, and the like. I have. In the projection display device 110 described with reference to FIG. 1, each of the three liquid crystal light valves 100 (the liquid crystal panel 101, the image processing circuit 202, the timing generation circuit 203, the power supply circuit 201, etc.) is red (R). The liquid crystal light valve 100 (R), the green (G) liquid crystal light valve 100 (G), and the blue (B) liquid crystal light valve 100 (B) are used.

  The image processing circuit 202, the timing generation circuit 203, and the power supply circuit 201 are configured by an IC or the like mounted on a flexible substrate 108 (see FIGS. 3A and 3B) connected to the liquid crystal panel 101. In the timing generation circuit 203, a dot clock for driving each pixel 100b of the liquid crystal panel 101 is generated, and a clock signal, an inverted clock signal, and a transfer start are generated based on the dot clock. When input image data is input from the outside, the image processing circuit 202 generates an image signal based on the input image data and supplies the image signal to the liquid crystal panel 101. The power supply circuit 201 generates a plurality of power supplies and supplies them to the liquid crystal panel 101.

  The liquid crystal panel 101 includes a pixel array region 10b in which a plurality of pixels 100b are arrayed in a central region. Among the regions partitioned by the thick dashed line in the pixel array region 10b, the central region is the image display region 10a in which a plurality of display pixels 100a are arrayed, and the outer region is inside the sealing material formation region described later. Is a dummy pixel region 10d in which dummy pixels 100d that do not directly contribute to display are arranged.

  In the liquid crystal panel 101, a plurality of data lines 6a and a plurality of scanning lines 3a extend vertically and horizontally inside the pixel array region 10b on the element substrate 10 to be described later, and the pixels are located at positions corresponding to the intersections thereof. 100b is configured. In the plurality of pixels 100b, the thin film transistor 30 and the pixel electrode 9a serving as pixel switching elements are formed in both the display pixel 100a and the dummy pixel 100d. The data line 6 a is electrically connected to the source of the thin film transistor 30, the scanning line 3 a is electrically connected to the gate of the thin film transistor 30, and the pixel electrode 9 a is electrically connected to the drain of the thin film transistor 30.

  In the element substrate 10, a scanning line driving circuit 104 and a data line driving circuit 105 are configured outside the pixel array region 10 b. The data line driving circuit 105 is electrically connected to the data line 6a and sequentially supplies image signals to the data lines 6a. The scanning line driving circuit 104 is electrically connected to the scanning line 3a, and sequentially supplies the scanning signal to each scanning line 3a.

  In each pixel 100b, the pixel electrode 9a is opposed to a common electrode formed on a counter substrate, which will be described later, via a liquid crystal, and constitutes a liquid crystal capacitor 50a. Each pixel 100b is provided with a holding capacitor 60 in parallel with the liquid crystal capacitor 50a in order to prevent the image signal held in the liquid crystal capacitor 50a from leaking. In this embodiment, in order to form the storage capacitor 60, the capacitor line 3b is formed in parallel with the scanning line 3a, and the capacitor line 3b is connected to a common potential line (not shown) and has a predetermined potential. Is held in. The storage capacitor 60 may be formed between the preceding scanning line 3a.

  As will be described in detail later, in the present embodiment, in the element substrate 10, for example, each of the dummy pixels 100d arranged on the side opposite to the side where the data line driving circuit 105 is located, the photo sensor element 40 is formed. The detection result of the optical sensor element 40 is output to the control circuit 45 outside the liquid crystal panel 101 via the signal line 47. Here, the control circuit 45 is a common control circuit for the liquid crystal light valves 100 (R), (G), and (B) corresponding to red (R), green (G), and blue (B). The light reception results of the optical sensor elements 40 of the liquid crystal light valves 100 (R), (G), and (B) are compared, and based on the results, the liquid crystal light valves 100 (R), (G), ( The pixel processing circuit 202 in B) is controlled.

(Specific configuration of the liquid crystal panel 101)
3A and 3B are plan views of the liquid crystal light valve 100 (R), (G), and (B) to which the present invention is applied as viewed from the counter substrate side together with the respective components. And HH ′ sectional view thereof.

  As shown in FIGS. 3A and 3B, in the liquid crystal panel 101 of the liquid crystal light valve 100, the element substrate 10, a quartz substrate, a heat-resistant glass substrate, and the like are used as base materials through a predetermined gap. The counter substrate 20 is bonded by a sealing material 107 (a region with a slanted line in FIG. 3A), and the sealing material 107 is disposed along the outer peripheral edge of the counter substrate 20. Here, the counter substrate 20 is disposed on the side where the color light is incident from the light source unit 150 described with reference to FIG. 1, and the element substrate 10 is disposed on the emission side of the modulated light.

  The sealing material 107 is an adhesive made of a photo-curing resin, a thermosetting resin, or the like, and is mixed with a gap material such as glass fiber or glass beads for setting the distance between both substrates to a predetermined value. In a corner portion of the counter substrate 20 and the like, a vertical conductive material (not shown) is formed for electrical conduction between the element substrate 10 and the counter substrate 20.

  In the element substrate 10, a data line driving circuit 105 and a plurality of terminals 102 are formed along one side of the element substrate 10 in a region outside the inner periphery of the sealing material 107, and along the side adjacent to the one side. A scanning line driving circuit 104 is formed. In addition, a flexible substrate 108 is connected to the element substrate 10 by a terminal 102. The element substrate 10 may include a protection circuit and an inspection circuit for protecting the pixel array region 10b, the data line driving circuit 105, and the scanning line driving circuit 104 from static electricity, but the description thereof is omitted. To do.

  As will be described in detail later, pixel electrodes 9 a are formed in a matrix on the element substrate 10. On the counter substrate 20, a frame-shaped light-shielding film 23 b (a region with a diagonal line rising to the right in FIG. 3A) is formed in the inner region of the sealing material 107, and the inner side is an image display region 10 a. The dummy pixel region 10d described with reference to FIG. 2 is disposed in a region overlapping the light shielding film 23b. In the counter substrate 20, a light shielding film 23 a called a black matrix or a black stripe is formed in a region facing the vertical and horizontal boundary regions of the pixel electrode 9 a of the element substrate 10. The counter electrode 21 is formed.

  The light-shielding film 23b has an opening 23c that overlaps the optical sensor element 40 described with reference to FIG. 2, and the light from the light source unit 150 described with reference to FIG. It is possible to reach In FIG. 3A, the opening 23c has a shape extending in a slit shape in the direction in which the photosensor elements 40 are arranged, but corresponds to a region where the photosensor elements 40 are formed. Alternatively, it may be formed in a dot shape.

  In a space surrounded by the sealing material 107, a liquid crystal layer 50 as an electro-optical material is sealed. The liquid crystal layer 50 takes a predetermined alignment state by the alignment films 16 and 22 (see FIG. 4) formed on the element substrate 10 and the counter substrate in a state where an electric field from the pixel electrode 9a is not applied. The liquid crystal layer 50 is made of, for example, one or a mixture of several types of nematic liquid crystals.

(Configuration of each pixel)
FIG. 4 is a cross-sectional view schematically showing the configuration of the end of the image display area 10a and the dummy pixel area 10d of the liquid crystal light valve 100 to which the present invention is applied.

  As shown in FIG. 4, the element substrate 10 has a base protective film 12 made of a silicon oxide film or the like formed on the surface of a translucent substrate 10s made of a quartz substrate, a heat-resistant glass substrate, or the like. The N-channel thin film transistor 30 is formed in both the display pixel 100a in the image display region 10a and the dummy pixel 100d in the dummy pixel region 10d. In the thin film transistor 30, a source region, a channel region, and a drain region are arranged in this order in the island-shaped semiconductor film 1a. A gate insulating film 2 made of a silicon oxide film or the like is formed above the semiconductor film 1a, and a scanning line 3a is formed above the gate insulating film 2. A part of the scanning line 3a is opposed to the channel region through the gate insulating film 2 as a gate electrode. The semiconductor film 1a is, for example, a low-temperature polysilicon film (low-temperature polysilicon film) that is polycrystallized by laser annealing, lamp annealing, or the like after an amorphous silicon film is formed on the translucent substrate 10s. It is a high-temperature polysilicon film obtained by polycrystallizing an amorphous silicon film at a temperature, or a single crystal silicon layer. On the upper layer side of the thin film transistor 30, interlayer insulating films 7 and 8 are formed. A data line 6 a and a drain electrode 6 b are formed on the surface of the interlayer insulating film 7, and the data line 6 a is electrically connected to the source region through a contact hole formed in the interlayer insulating film 7. A pixel electrode 9 a made of an ITO film is formed on the surface of the interlayer insulating film 8. The pixel electrode 9 a is electrically connected to the drain electrode 6 b through a contact hole formed in the interlayer insulating film 8, and the drain electrode 6 b has a contact hole formed in the interlayer insulating film 7 and the gate insulating film 2. And is electrically connected to the high concentration drain region. An alignment film 16 made of a polyimide film is formed on the surface side of the pixel electrode 9a. Although not shown, the portion extending from the drain region (lower electrode) is the same layer as the scanning line 3a via an insulating film (dielectric film) formed simultaneously with the gate insulating film 2. The capacitor lines 3b face each other as the upper electrode, so that the storage capacitor 60 described with reference to FIG. 1 is configured.

  In the counter substrate 20, a light shielding film 23a called a black matrix or a black stripe and a frame-shaped light shielding film 23b are formed on the surface of a light transmitting substrate 20s. In addition, an opening 23c is formed in the light shielding film 23b covering the dummy pixel region 10d (dummy pixel 100d). Further, a planarization protective film 24 is formed so as to cover the light shielding films 23 a and 23 b, and a counter electrode 21 made of an ITO film and an alignment film 26 are formed on the surface of the planarization protective film 24.

(Configuration of the optical sensor element 40)
In the liquid crystal light valves 100 (R), (G), and (B) of the present embodiment, in the element substrate 10, a PIN type is formed on the base insulating film 12 on the lower layer side of the pixel electrode 9a formed in the dummy pixel region 10d. An optical sensor element 40 made of a photodiode is formed. The optical sensor element 40 has a structure in which, for example, an N-type silicon layer 41, an intrinsic silicon layer 42, and a P-type silicon layer 43, which are formed simultaneously with the source region and the drain region of the thin film transistor 30, are stacked in this order. The P-type silicon layer 43 can be formed simultaneously with the scanning line 3a, for example. In configuring the optical sensor element 40, an intrinsic region may be left in the center of the common silicon layer, and an N-type region and a P-type region may be formed on both sides thereof.

  In the element substrate 10, on the lower layer side of the thin film transistor 30, a light shielding film 5 a for preventing reflected light from entering the thin film transistor 30 is formed between the transparent substrate 10 s and the base protective film 12. ing. Further, on the lower layer side of the optical sensor element 40, a light shielding film 5 b for preventing reflected light from entering the optical sensor element 40 is formed between the light-transmitting substrate 10 s and the base protective film 12. Yes.

  In the liquid crystal light valve 100, the first polarizing plates 115b, 116b, and 117b (see FIG. 1) are arranged on the light incident side (opposite substrate 20 side) of the liquid crystal panel 101, and the light emission side of the liquid crystal panel 101 is disposed. Second polarizing plates 115d, 116d, and 117d (see FIG. 1) are disposed on the element substrate 10 side.

(Operation and main effect of this form)
With reference to FIG. 5, the operation and main effects of the liquid crystal light valve 100 (R), (G), and (B) of the present embodiment will be described. FIG. 5 is an explanatory diagram showing the luminance balance of the liquid crystal light valves of the respective colors.

  In the liquid crystal light valves 100 (R), (G), and (B) of the present embodiment, the orientation of the liquid crystal layer 50 is controlled by the drive voltage applied between the pixel electrode 9a and the counter electrode 21, and the arrow L1 As shown, the light of each color emitted from the light source unit 150 is modulated and emitted.

At this time, normally, considering the visibility of colored light, the set luminances of red (R), green (G), and blue (B) are shown by solid lines LR0, LG0, and LB0 in FIG. In addition, the luminance has the following relationship: Green (G)> Blue (B)> Red (R)
Is initially set. This luminance is the luminance at the same gradation in red (R), green (G), and blue (B).

  In the liquid crystal light valves 100 (R), (G), and (B), the liquid crystal layer 50 is also applied to the dummy pixel region 10d (dummy pixel 100d) by the drive voltage applied between the pixel electrode 9a and the counter electrode 21. Is controlled.

  In this embodiment, in any of the liquid crystal light valves 100 (R), (G), and (B), the light of each color emitted from the light source unit 150 is transmitted through the liquid crystal layer 50 as indicated by the arrow L2. The light enters the optical sensor element 40. The light reception results of the optical sensor elements 40 formed in the liquid crystal light valves 100 (R), (G), and (B) are output to a common control circuit 45. The received light amounts of the optical sensor elements 40 configured as 100 (R), (G), and (B) are compared. In this comparison result, if the balance of the incident light amounts of the respective color lights is the same as in the initial state, the set luminance shown in FIG. 5A is maintained, and a high-quality color image can be displayed.

On the other hand, in the result of comparing the amount of light received by the optical sensor element 40 configured in each of the liquid crystal light valves 100 (R), (G), and (B), the balance of the incident light amount of each color light is from the initial state. For example, it is assumed that the incident light amount of blue (B) light is reduced. In such a state, the luminance of blue (B) decreases as shown by the dotted line LB1 in FIG.
Green (G)> Red (R)> Blue (B)
Become. In such a case, the control circuit 45 reduces the luminance with respect to the image processing circuit 202 configured in the red (R) and green (G) liquid crystal light valves 100 (R) and (G). Command. As a result, in the red (R) and green (G) liquid crystal light valves 100 (R) and (G), the signal level applied to the pixel electrode 9a is corrected, and the dotted lines LR1 and LG1 in FIG. As shown, the red (R) and green (G) brightness decreases. Therefore, the luminance of red (R), green (G), and blue (B) is the following initial setting relationship: green (G)> blue (B)> red (R)
Therefore, even when the amount of specific color light is reduced due to the deterioration of the light source 112 used in the light source unit 15, a high-quality color image can be displayed.

[Other configuration examples of liquid crystal light valves]
FIG. 5 is a cross-sectional view schematically showing a configuration of an end portion of an image display region and a dummy pixel region of another liquid crystal light valve used in the projection display device to which the present invention is applied. The basic configuration of the present embodiment is substantially the same as that described with reference to FIGS. 1 to 4, and therefore, common portions are denoted by the same reference numerals and illustrated. Description is omitted.

  In the liquid crystal light valves 100 (R), (G), and (B) described with reference to FIGS. 1 to 4, the pixel electrode 9 a made of an ITO film is formed on the interlayer insulating film 8. The second polarizing plates 115d, 116d, and 117d are arranged on the light emission side (the element substrate 10 side). In this embodiment, as shown in FIG. 6, both the display pixel 100a and the dummy pixel 100d are used. A wire grid polarizer 9b is formed. For this reason, in the liquid crystal light valve 100, the first polarizing plates 115b, 116b, and 117b are arranged on the light incident side (opposite substrate 20 side) of the liquid crystal panel 101. A polarizing plate is not disposed on the element substrate 10 side.

  Here, the wire grid polarizer 9b is made of a metal film formed in a stripe shape with a pitch smaller than the wavelength of incident light, and the stripe portions are connected to each other and formed in the interlayer insulating films 7 and 8. It is electrically connected to the drain electrode 6b through the contact hole. For this reason, in this embodiment, the wire grid polarizer 9b also functions as a pixel electrode. The wire grid polarizer 9b is covered with a light-transmitting low refractive index layer 9c such as a silicon oxide film, and the low refractive index layer 9c is filled between the stripe portions. When the refractive index of the alignment film 16 is low, the space between the stripe portions may be filled with the alignment film 16, and the formation of the low refractive index layer 9c may be omitted. Moreover, as a metal film used for the wire grid polarizer 9b, aluminum, silver, tungsten, titanium, or an alloy thereof can be used.

  Also in the liquid crystal light valves 100 (R), (G), and (B) of this embodiment, a wire grid polarizer formed in the dummy pixel region 10 d is provided on the element substrate 10 as in the configuration described with reference to FIG. An optical sensor element 40 made of a PIN type photodiode is formed on the lower layer side of 9b (pixel electrode). The optical sensor element 40 includes an N-type silicon layer 41, an intrinsic silicon layer 42, A P-type silicon layer 43 is stacked in this order.

  In the element substrate 10, on the lower layer side of the thin film transistor 30, a light shielding film 5 a for preventing reflected light from entering the thin film transistor 30 is formed between the transparent substrate 10 s and the base protective film 12. ing. Further, on the lower layer side of the optical sensor element 40, a light shielding film 5 b for preventing reflected light from entering the optical sensor element 40 is formed between the light-transmitting substrate 10 s and the base protective film 12. Yes.

  In the liquid crystal light valves 100 (R), (G), and (B) configured as described above, for example, when light of each color is emitted from the light source unit 150, the first polarizing plates 115b, 116b, and 117b Only polarized light enters the liquid crystal panel 101. For this reason, when a voltage is not applied to the liquid crystal layer 50, the light emitted from the liquid crystal layer 50 is S-polarized light, and therefore black display (dark display) is obtained. Further, in the dummy pixel 100d, the light emitted from the light source unit 150 does not reach the photosensor element 40.

  On the other hand, when a voltage is applied to the liquid crystal layer 50, the light emitted from the liquid crystal layer 50 is P-polarized light, so that white display (bright display) is obtained. Therefore, in the dummy pixel 100d, the light emitted from the light source unit 150 is received by the photosensor element 40 as indicated by the arrow L2.

  The light reception results of the optical sensor elements 40 configured in the liquid crystal light valves 100 (R), (G), and (B) are output to the common control circuit 45 shown in FIG. The received light amounts of the optical sensor elements 40 configured in the liquid crystal light valves 100 (R), (G), and (B) are compared. In this comparison result, if the balance of the incident light amounts of the respective color lights is the same as in the initial state, the set luminance shown in FIG. 5A is maintained, and a high-quality color image can be displayed.

On the other hand, in the result of comparing the amount of light received by the optical sensor elements 40 configured in the liquid crystal light valves 100 (R), (G), and (B), the balance of the incident light amounts of the respective color lights from the initial state When the liquid crystal layer 50 is broken or when the liquid crystal layer 50 is deteriorated, for example, the luminance of blue (B) light decreases as indicated by a dotted line LB1 in FIG. 5B. In such a state, the luminance balance in each of the liquid crystal light valves 100 (R), (G), and (B) is as follows: green (G)> red (R)> blue (B)
Become. Therefore, the control circuit 45 instructs the image processing circuit 202 configured for the red (R) and green (G) liquid crystal light valves 100 (R) and (G) to reduce the luminance. As a result, as indicated by dotted lines LR1 and LG1 in FIG. 5C, the luminance of red (R) and green (G) decreases, so that the luminance of red (R), green (G), and blue (B) Is the following initial setting relationship: Green (G)> Blue (B)> Red (R)
It is corrected to. Therefore, a high-quality color image can be displayed.

  Thus, in this embodiment, since the wire grid polarizer 9b is disposed between the liquid crystal layer 50 and the optical sensor element 40, the degree of deterioration of the liquid crystal layer 50 is reflected in the light reception result of the optical sensor element 40. Therefore, based on the light reception result, the luminance balance can be reliably corrected including all of the effects of the balance of the incident light amount in each color light and the deterioration degree of the liquid crystal layer 50.

  In this embodiment, the wire grid polarizer 9b functions as a pixel electrode, but both the pixel electrode and the wire grid polarizer may be formed. In addition, the wire grid polarizer may be formed only in a region overlapping with the optical sensor element 40, and the pixel electrode of the display pixel 100a may be formed of an ITO film. The degree of deterioration of the liquid crystal layer 50 can be reflected on the light reception result of the optical sensor element 40.

[Other embodiments]
In the above embodiment, as the light source unit 15, the white light emitted from the light source 112 is separated into red (R), green (G), and blue (B) light by the color separation optical system, and the liquid crystal light valve 100 (R). , (G), (B), the luminance balance was corrected by adjusting the signal level applied to the pixel electrode 9a, but red (R), green (G), blue (B) When a light source unit including an LED element or an organic EL element that emits light is used, instead of adjusting the signal level applied to the pixel electrode 9a, or in addition to adjusting the signal level applied to the pixel electrode 9a The brightness balance may be corrected by adjusting the light emission balance from the red (R), green (G), and blue (B) light emitting elements by adjusting the driving conditions for the light emitting elements.

  In the above embodiment, since a plurality of photosensor elements 40 are used in parallel, a large detection current can be obtained, but one photosensor element 40 may be provided depending on the sensitivity. In order to eliminate the influence of the dark current of the photosensor element 40, a reference photosensor element may be provided, and the light from the light source unit 15 may be detected by the differential output.

  Moreover, in the said form, although the photo sensor element 40 was formed in the dummy pixel 100d, you may form the photo sensor element 40 in area | regions other than the dummy pixel 100d.

It is a schematic block diagram of the projection type display apparatus (liquid crystal projector) to which this invention is applied. It is a block diagram which shows electrical structures, such as a liquid crystal light valve used for the projection type display apparatus to which this invention is applied. (A), (b) is the top view which looked at the liquid crystal panel of the liquid crystal light valve used for the projection type display apparatus to which this invention was applied from the opposing board | substrate side with each component, and its HH 'cross section FIG. FIG. 4 is a cross-sectional view schematically showing a configuration of an end portion of an image display region and a dummy pixel region of the liquid crystal light valve shown in FIG. 3. It is explanatory drawing which shows the luminance balance of the liquid crystal light valve of each color. It is sectional drawing which shows typically the structure of the edge part of the image display area of another liquid crystal light valve used for the projection type display apparatus to which this invention is applied, and a dummy pixel area | region.

Explanation of symbols

9a ... Pixel electrode, 9b Wire grit polarizer, 10 ... Element substrate, 10a ... Image display area, 10d ... Dummy pixel area, 20 ... Counter substrate, 30 ... Thin film transistor, 40 ... Optical sensor Element 45 ··· Control circuit 100 (R), (G), (B) ··· Liquid crystal light valve, 100a · · Display pixel, 100d · · Dummy pixel, 101 (R), (G), (B) ..Liquid crystal panel, 110 ..Projection display device, 202 ..Image processing circuit

Claims (4)

A light source unit that emits a plurality of types of color light, a plurality of liquid crystal light valves that light-modulate each of the plurality of color lights emitted from the light source unit, and a modulated light that is emitted from the plurality of liquid crystal light valves In a projection type display device having a combined optical system that emits light and a projection optical system that projects light emitted from the combined projection system,
Each of the plurality of liquid crystal light valves is disposed opposite to the element substrate on the side on which the colored light is incident, and an element substrate having a pixel electrode and a pixel switching element for each of the plurality of display pixels arranged in the image display area. A translucent counter substrate, and a liquid crystal held between the counter substrate and the element substrate,
The element substrate is formed with an optical sensor element capable of receiving light incident from the counter substrate side outside the image display region,
A projection type display device, wherein a luminance balance in the plurality of liquid crystal light valves is corrected based on a light reception result of the photosensor element. A pixel electrode and a pixel switching element are provided outside the image display area in the element substrate and inside a sealing material that partitions the liquid crystal holding area between the element substrate and the counter substrate. A dummy pixel region in which dummy pixels that do not directly contribute to are formed,
The projection display device according to claim 1, wherein the photosensor element is formed in a position overlapping with the pixel electrode on the lower layer side of the pixel electrode in the dummy pixel region.   Of the display pixel and the dummy pixel, at least the dummy pixel is formed in a stripe shape having a smaller pitch than the wavelength of incident light and forms a pixel electrode, and the pixel electrode and the light. The projection display device according to claim 2, further comprising: a wire grid polarizer formed in a stripe shape having a pitch smaller than a wavelength of light incident between the sensor element and the sensor element.   4. The projection display device according to claim 1, wherein the brightness balance is performed by adjusting a signal level applied to the pixel electrode. 5.

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