JPH0996805A - Projection type display device and liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the degradation in image grade and to obtain high quality, high luminance and high contrast by forming an antireflection film where the wavelength of light to minimize reflectivity exists on the surface of a polarizing plate, thereby lessening the light incident by the return light from the exit side of a TFT liquid crystal panel to the panel. SOLUTION: The luminous flux radiated from a light source 1 transmits the incident side polarizing plate 4 via a reflection plate 2 and is made into linearly polarized light which is then made incident on the TFT liquid crystal panel 5. The exit side polarizing plate 6 is stuck to the exit surface of the TFT liquid crystal panel 5 so as to come optically into tight contact therewith. The light transmitted through the TFT liquid crystal panel 5 is projected via an optical system 8 for projection to a screen. An antireflection film (the film in which the wavelength of the light to minimize the reflectivity exists between 400 to 500nm) which emphatically prevents the reflection of the surface reflection on the short wavelength side is formed on the surface of the exit side polarizing plate 6. As a result, the irradiation of the TFT panel with the light of the high sensitivity is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel (hereinafter referred to as a TFT liquid crystal panel) in which liquid crystal is sealed between a pair of substrates and a thin film transistor and a pixel electrode connected to the thin film transistor are formed on the inner surface of one substrate. The present invention also relates to a projection display device using the TFT liquid crystal panel as a light valve.

[0002]

2. Description of the Related Art Various types of projection type liquid crystal display devices for projecting and displaying a color image using a TFT liquid crystal panel are known.

FIG. 1 shows the configuration of an optical system of a projection type liquid crystal display device which is generally used. In the figure, 1 is a light source lamp, and the light from this is emitted toward the color separation optical system 3 side via a reflection plate 2. The color separation optical system 3 includes dichroic mirrors 31, 32 and a mirror 33. The dichroic mirror 31 transmits the red light flux R but reflects the green and blue light fluxes G and B, and the other dichroic mirror 32 reflects the green light flux G but transmits the blue light flux B. . These two dichroic mirrors 31 and 32 convert the white light flux W into the red, green, and blue color fluxes R, G, and B.
Is separated into The separated luminous fluxes of the respective colors are transmitted through the incident-side polarization plates 41, 42, 43 and become linearly polarized light, and then the three TFT liquid crystal panels 51, 5 corresponding to the respective colors.
It is incident on 2, 53.

Emission side polarization plates 61, 62 and 63 are attached to the emission surfaces of the respective TFT liquid crystal panels 51, 52 and 53 so as to be in close optical contact with each other, and the light is incident on the basis of given image information. Modulate the luminous flux. The modulated light fluxes R, G, and B of the respective colors enter the color combining optical system 7 including the dichroic mirrors 71 and 72 and the mirror 73, and are combined there. The combined modulated light flux is enlarged and projected on the surface of the screen outside the device via the projection lens optical system 8. In FIG. 1, the three TFT liquid crystal panels and the projection lens optical system are depicted as having different optical distances for each color, but in an actual projection display device, the distances are made equal. The color combining optical system shown in FIG.
It is also known that a prism optical system using a dichroic prism is used instead of the dichroic mirror as shown in FIG.

[0005]

When the TFT for controlling the display state of each pixel of the TFT liquid crystal panel is irradiated with intense light, the TFT irradiated with the light has an increased leak current. If the leak current of the TFT increases, accurate modulation corresponding to a given image signal cannot be realized, and the quality of the image enlarged and projected on the screen is significantly deteriorated. Therefore, a light shielding means such as a black matrix is provided on the light source side of the TFT so that the TFT is not directly irradiated with the light from the light source.

However, if the light is interface-reflected on the emission side surface of the TFT liquid crystal panel, the TFT is irradiated with the light. Referring to FIG. 2, the TFT liquid crystal panel 5 will be described.
A polarizing plate 61 is attached to the exit surface of No. 1, but the exit surface of this polarizing plate 61 is an air interface, and the refractive index changes significantly. A part of the light beam traveling toward the dichroic mirror 71 is reflected. The reflected light R1 enters the panel from the emission side of the TFT liquid crystal panel 51. This is TF
The same applies to the T liquid crystal panel 52 and the TFT liquid crystal panel 53.

FIG. 9 shows a coplanar type polysilicon TFT.
It is a figure which shows the cross section of the TFT liquid crystal panel using. TF
On the TFT element side substrate 501 of the T liquid crystal panel, TF
A polysilicon thin film 504 to be a source / drain channel of T is formed, and a gate electrode 503 is formed on the silicon thin film 504 via a gate insulating film. The source wiring 502 is connected to the source of the silicon film 504, and the pixel electrode 505 is connected to the drain. TF
A black matrix 508 that shields light and a counter electrode 509 of a transparent conductive film (ITO) are formed on a glass substrate 507 that is arranged to face the T element side substrate, and the pixel electrode 505 and the counter electrode 509 form a liquid crystal layer. An electric signal can be applied to 506. In the case of the projection type display device, the light flux incident on the liquid crystal panel is incident on the liquid crystal panel from the glass substrate 507 side. The channel portion 50 of the TFT is shielded by the black matrix 508.
4 is not directly irradiated with light, but the channel portion 504 is exposed from the TFT element side substrate. Therefore, the reflected light on the emission surface of the TFT liquid crystal panel and the polarizing plate 6
When the reflected light on the exit surface of No. 1 is refracted and enters, the channel portion 504 of the TFT is irradiated with the light, so that the leak current of the TFT increases.

On the other hand, an inverted stagger type amorphous silicon TFT liquid crystal panel has a cross section as shown in FIG. A TFT gate electrode 503 is formed on a TFT element side substrate 501 of a TFT liquid crystal panel, and an amorphous silicon film 504 which serves as a channel is formed on this gate electrode via a gate insulating film. Further, an amorphous silicon thin film serving as a source / drain is formed on this silicon film, and a source wiring 502 is formed on the source.
, And the pixel electrode 505 is connected to the drain. A black matrix 508 that shields light and a counter electrode 509 of a transparent conductive film (ITO) are formed on a glass substrate 507 that is arranged to face the TFT element side substrate. The pixel electrode 505 and the counter electrode 509 form a liquid crystal layer. Fifty
An electric signal can be applied to 6. In this type of TFT, the gate electrode 503 normally uses a metal that blocks light. For this reason,
Even if the reflected light from the emission surface of the TFT liquid crystal panel and the emission surface of the polarizing plate 61 enters, the channel portion 504 is not directly irradiated with the light. However, even in this case, the reflected light is refracted and the TFT source
Since light is irradiated to the end of the gate, the leak current of the TFT increases when strong light enters from the emission surface of the TFT liquid crystal panel.

Although a method of forming a light shielding means under the TFT has been proposed for both TFTs, most projections are subject to various restrictions from the viewpoint of avoiding complication of the process and ensuring the aperture ratio. Type display device, TF
At present, it is not possible to completely prevent the interface reflected light on the emission side surface of the T liquid crystal panel.

In order to prevent such interface reflection, the interface of the optical element is generally surface-treated with an antireflection film. By the way, in the projection type display device, it is usual that components other than visible light such as infrared rays and ultraviolet rays are removed by an optical filter before the light from the light source enters the liquid crystal panel. Further, since the polarizing plate almost absorbs light having a wavelength shorter than 400 nm, the antireflection film has a characteristic that the reflectance is close to zero in the whole wavelength region of visible light having a wavelength longer than 400 nm. It is desirable to do. However, in practice, it is very difficult to form an antireflection film having a reflectance close to zero in the entire visible wavelength region. By the way, the visibility of human eyes has wavelength dependence as shown in FIG. The visual sensitivity has a peak at 550 nm, and the sensitivity becomes lower at shorter wavelengths and longer wavelengths. Even with the same amount of reflected light, light having a wavelength with high visibility is easily noticeable, and light with a wavelength having low visibility is less noticeable. Therefore, the characteristics of the conventional antireflection film have been designed so that the visible reflected light is minimized, that is, the reflectance in the vicinity of 550 nm where the visibility is highest is minimized. Since such an antireflection film has a high antireflection effect for light with a wavelength of about 500 nm to about 600 nm, it can prevent interfacial reflection, but it does not reflect light with a short wavelength or a long wavelength with low visibility. The effect of prevention was low and it was not possible to sufficiently prevent interface reflection.

However, light having a wavelength that tends to increase the leak current of the TFT of the TFT liquid crystal panel is different from light that is easily visible to human eyes. FIG. 4 shows the wavelength dependence of the absorption coefficient of polysilicon forming the transistor. Here, since light having a wavelength shorter than 400 nm including ultraviolet rays is absorbed by the polarizing plate and does not actually pose a problem, it is not shown in the figure. From FIG. 4, the absorption coefficient increases as the wavelength of light decreases, and decreases monotonically as the wavelength increases. From this, it is understood that the shorter the wavelength of the TFT, the more the leak current increases with a smaller amount of light.

Therefore, since the conventional antireflection film has a small antireflection effect for light of short wavelength having low luminosity, it is possible to prevent the problem that the leak current of the transistor of the TFT liquid crystal panel increases due to the light. The reality is that effective antireflection is not possible.

Here, the amount of such reflected light R1 naturally increases as the irradiation illuminance on the TFT liquid crystal panel increases. TF by increasing the light intensity of the light source
The higher the irradiation illuminance of the T liquid crystal panel, the higher the illuminance of the projected image on the screen, so that an image with high brightness and high contrast ratio can be projected even in a bright room. Therefore, in order to increase the screen illuminance, it is necessary to prevent short wavelength light from entering the TFT liquid crystal panel from the opposite direction.

The problem of the present invention is to pay attention to this point,
It is an object of the present invention to propose a high-quality projection liquid crystal display device capable of preventing the deterioration of image quality by reducing the incidence of light on the T liquid crystal panel due to the return light from its emission side.

Another object of the present invention is to provide a T liquid crystal panel with T out of the light incident on the TFT liquid crystal panel due to the return light from its emission side.
To propose a projection-type liquid crystal display device capable of realizing a projected image with high brightness and high contrast ratio by intensively reducing light having a short wavelength component having a high effect of increasing the leak current of FT. is there.

A further object of the present invention is to propose a liquid crystal panel which is optimal as a light valve for such a high quality, high brightness, high contrast projection display device.

[0017]

In order to solve the above-mentioned problems, a light source, a liquid crystal panel which modulates an incident light beam from the light source and emits it as an outgoing light beam, and the outgoing light beam is enlarged and projected on a screen. In the projection type display device having a projection optical means for the liquid crystal panel, liquid crystal is sealed between a pair of substrates, and a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of one of the substrates. And a polarizing plate is arranged outside the substrate on the exit side, and the liquid crystal panel is provided on the surface of the polarizing plate.
The wavelength of light for which the reflectance is minimum is 400 nm to 500 n
It is characterized in that an antireflection film existing between m is formed.

Further, in a projection type display device having a light source, a liquid crystal panel which modulates an incident light flux from the light source and emits it as an outgoing light flux, and projection optical means for enlarging and projecting the outgoing light flux on a screen. , The liquid crystal panel,
A liquid crystal is sealed between a pair of substrates, a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of the substrate on the emission side, and a polarizing plate is arranged on the outside of the substrate on the emission side. In the liquid crystal panel, the wavelength of light having the minimum reflectance is 400 n on the surface of the polarizing plate.
It is characterized in that an antireflection film existing between m and 500 nm is formed.

Further, in a projection display device having a light source, a liquid crystal panel that modulates an incident light beam from the light source and emits it as an emitted light beam, and projection optical means for enlarging and projecting the emitted light beam on a screen. In the liquid crystal panel, liquid crystal is sealed between a pair of substrates, a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on an inner surface of the one substrate, and an outer surface of the substrate on the emission side. In addition, it is characterized in that an antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm is formed.

Further, in a projection display device having a light source, a liquid crystal panel which modulates an incident light beam from the light source and emits it as an emitted light beam, and projection optical means for enlarging and projecting the emitted light beam on a screen. In the liquid crystal panel, liquid crystal is sealed between a pair of substrates, a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of the substrate on the emission side, and the substrate on the emission side is outside. The wavelength of the light with the minimum reflectance is 400 nm on the surface.
To 500 nm, an antireflection film is formed.

Liquid crystal is sealed between a pair of substrates arranged so as to face each other, and a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of one of the substrates to emit light. In a liquid crystal panel having a polarizing plate on the outer surface of the substrate, an antireflection film having a minimum reflectance of 400 nm to 500 nm is formed on the surface of the polarizing plate. It is characterized by

Further, liquid crystal is sealed between a pair of substrates arranged so as to face each other, and a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of one of the substrates, and the pair of substrates are connected to each other. In a liquid crystal panel in which a polarizing plate is arranged on the outer surface of the substrate, an antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm is formed on the surface of the polarizing plate. It is characterized by

Furthermore, liquid crystal is enclosed between a pair of substrates arranged so as to face each other, and a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of one of the substrates. In the panel,
On the outer surface of the one of the substrates, an antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm is formed.

Further, in the thin film transistor, a silicon thin film serving as a channel is formed on the inner surface of the substrate,
It is characterized in that a gate electrode is formed on the silicon thin film via a gate insulating film.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 5 is a diagram showing a projection type liquid crystal display device using a single transmission type TFT liquid crystal panel shown in FIG. 9 or 10 as a first embodiment of the present invention. .
In this device, the light flux emitted from the light source 1 passes through the incident side polarization plate 4 via the reflection plate 2 to become linearly polarized light, and then enters the TFT liquid crystal panel 5. An emission side polarization plate 6 is attached to the emission surface of the TFT liquid crystal panel 5 so as to be in close optical contact. The light transmitted through the TFT liquid crystal panel is projected on the screen via the projection optical system 8. The emission surface of the TFT liquid crystal panel 5 is the emission surface of the emission side polarization plate 6 and is the interface with the air. When no antireflection treatment was applied to this interface, the surface reflection was about 4.5% on average in the entire visible light range, as shown in FIG. When the image projected on the screen was examined, when the irradiation illuminance of the TFT liquid crystal panel 5 was about 600,000 lux or more in this state, the leak current of the TFT increased due to the returning light to the TFT liquid crystal panel 5 due to the interface reflection, and the image was displayed. It was confirmed that a defect would occur.

Then, the outgoing side polarizing plate 6 was replaced with a polarizing plate having a conventional general antireflection film formed on the outgoing surface, and the same confirmation was carried out. As shown in FIG. 7, the reflectance of the surface of the polarizing plate is suppressed to almost 0.2% or less with respect to the light having a wavelength of 550 nm around which visibility is high. However, the effect of preventing reflection is low for short-wavelength and long-wavelength light having low visibility. When the image projected on the screen was examined, when the illumination intensity of the TFT liquid crystal panel 5 became about 2,000,000 lux or more, the leak current of the TFT increased due to the returning light to the TFT liquid crystal panel 5 due to the interface reflection, and the image defect occurred. It was confirmed to do.

Next, as shown in FIG. 8, the output side polarizing plate 6 is provided with an antireflection film for mainly preventing reflection on the short wavelength side (light having a minimum reflectance of 400 nm to 500 n).
The film existing between m) was replaced with a polarizing plate formed on the light emitting surface, and the same confirmation was performed. The reflectance of the surface of the polarizing plate has a lower anti-reflection effect for light having a peripheral wavelength of 550 nm, which has higher visibility than the characteristics of the anti-reflection film shown in FIG. As a result of the examination, no defect in the image due to an increase in the leak current of the TFT due to the returning light to the TFT liquid crystal panel due to the interface reflection up to the irradiation illuminance of the TFT liquid crystal panel 5 of about 3.3 million lux was not confirmed. When reflection at the interface between the TFT element side substrate 501 and the emission side polarization plate 6 poses a problem, the antireflection film is formed on the light incident surface side surface of the polarization plate or the emission side surface of the substrate 501. May be.

The projection type crystal display device of the present invention prevents the adverse effect of reflected light on the TFT panel even when the irradiation illuminance of the TFT liquid crystal panel is increased by about 1.5 times as compared with the conventional general device. It was confirmed that it was possible. In the embodiment of the present invention, it is possible to irradiate the TFT panel with light having a higher illuminance than before, and thus it is possible to reproduce on the screen a projected image having higher brightness and higher contrast ratio than before. .

(Embodiment 2) FIG. 1 is a diagram showing a projection type liquid crystal display using three transmission type TFT liquid crystal panels shown in FIG. 9 or 10 as a second embodiment of the present invention. In the figure, 1 is a light source lamp, and the light from this is a reflector plate 2.
The light is emitted toward the color separation optical system 3 side via. The color separation optical system 3 includes dichroic mirrors 31, 32 and a mirror 33. The dichroic mirror 31 transmits the red light flux R but reflects the green and blue light fluxes G and B, and the other dichroic mirror 32 reflects the green light flux G but transmits the blue light flux B. . These two dichroic mirrors 31 and 32 convert the white light flux W into the red, green, and blue color fluxes R, G, and B.
Is separated into The separated luminous fluxes of the respective colors are transmitted through the incident-side polarization plates 41, 42, 43 and become linearly polarized light, and then the three TFT liquid crystal panels 51, 5 corresponding to the respective colors.
It is incident on 2, 53.

As shown in FIG. 8, the emission surfaces of the TFT liquid crystal panels 51, 52 and 53 each have an antireflection film (surface of reflection) which mainly prevents reflection on the short wavelength side (light having a minimum reflectance). A film existing in the wavelength range of 400 nm to 500 nm) is formed on the light emission surface, and the emission side polarization plates 61, 62,
63 is attached so as to be optically in close contact with each other, and the incident light flux is modulated based on the given image information. The modulated light fluxes R, G, B of the respective colors are transmitted to the dichroic mirror 7.
The light enters the color combining optical system 7 including the mirrors 1, 72 and the mirror 73 and is combined there. The combined modulated light flux is enlarged and projected on the surface of the screen outside the device via the projection lens optical system 8. When reflection at the interface between the TFT element side substrate 501 and the emission side polarization plate 6 poses a problem, the antireflection film is formed on the light incident surface side surface of the polarization plate or the emission side surface of the substrate 501. May be.

In the conventional projection type liquid crystal display device, if the light amount of the light source 1 is increased, the display light is defective due to the reflected light to the TFT liquid crystal panel. This defect first occurs in the TFT liquid crystal panel 53 that modulates the blue light flux having the light on the short wavelength side. Therefore, the light amount of the light source 1 is
It was necessary to limit the liquid crystal panel 53 to the extent that no problem occurred.

It was confirmed that in the projection type liquid crystal display device of the present invention, even if the irradiation illuminance of the TFT liquid crystal panel 53 is about three times as high as the conventional one, the adverse effect of reflected light can be prevented. Therefore, it is possible to irradiate the TFT liquid crystal panel with light having a higher illuminance than before, and it is possible to reproduce a projected image with higher brightness and higher contrast ratio on the screen than before. In the present invention, since a liquid crystal panel that modulates light on the short wavelength side easily causes a problem, by forming the antireflection film only on the exit side polarization plate 63 of the TFT liquid crystal panel 53 that modulates blue light. It is also possible to reduce the cost.

In the above embodiments, the TFT liquid crystal panel having a polarizing plate formed on its output side surface has been described as an example, but the output side polarizing plate (analyzer) is separated from the TFT liquid crystal panel. In the case of a projection type display device or a projection type display device that does not use a polarizing plate, the surface of the TFT liquid crystal panel substrate on the emission side has a wavelength of light with a minimum reflectance of 400 nm. The same effect can be obtained by forming the antireflection film existing between 500 nm.

Further, a TFT in which a light shielding film for shielding the reflected light from the light emitting side is formed on the inner surface of the substrate of the TFT liquid crystal panel
Even in a liquid crystal panel, the light-shielding portion cannot be made large in order to improve the aperture ratio, so that the reflected light refracted from the interface is T
Easy to reach the FT element. Therefore, even in such a panel, the same effect can be obtained by forming an antireflection film on the emission side surface of the panel substrate, where the wavelength of the light having the minimum reflectance is 400 nm to 500 nm. Obtainable.

(Embodiment 3) FIG. 11 is a diagram showing a projection type liquid crystal display using three TFT liquid crystal panels shown in FIG. 9 or 10 as a third embodiment of the present invention. In the figure, reference numeral 1 denotes a light source lamp, light from which is reflected by a reflection plate 2, heat rays in the infrared region are cut by a heat ray cut filter 601, and emitted toward the color separation optical system side. The color separation optical system includes a dichroic mirror 602,
603 is provided. Dichroic mirror 602
A blue reflection dichroic mirror that reflects a blue light flux (wavelength of about 500 nm or less) and transmits other light (yellow light). The reflected blue luminous flux is reflected by the reflection mirror 60.
The incident light is incident on the TFT liquid crystal panel 53 that changes the direction by 4 and modulates the blue light flux. The light transmitted through the dichroic mirror 602 enters the green reflection dichroic mirror, reflects the green light flux (light having a wavelength of approximately 500 nm to 600 nm), and the other light, the red light flux (light having a wavelength of approximately 600 nm or more). ) Through. The reflected green light is incident on the TFT liquid crystal panel 52 that modulates the green light flux. The red light flux that has passed through the dichroic mirror 603 changes its direction by the reflection mirrors 605 and 606 and is incident on the TFT liquid crystal panel 51 that modulates the red light flux. Each color light is modulated by each transmissive TFT liquid crystal panel and combined by a dichroic prism. The dichroic prism has a blue light reflecting surface 60.
7. The red light reflection surface 608 is configured to be orthogonal to each other. The color image thus combined is enlarged and projected on the screen by the projection lens 8.

Incident-side polarization plates 41, 42, and 43 are closely attached to the incident sides of the TFT liquid crystal panels 51, 52, and 53, respectively. On the other hand, on the emission surface of the panel, as shown in FIG. 8, each surface has an antireflection film that intensively prevents reflection on the short wavelength side (the light having the minimum reflectance exists between 400 nm and 500 nm). Membrane)
The emission side polarization plates 61, 62, 63 formed on the light emission surface are attached so as to be in close optical contact with each other, and the incident light flux is modulated based on the given image information. In addition, TFT
When reflection at the interface between the element-side substrate 501 and the exit-side polarizing plate 6 poses a problem, the antireflection film may be formed on the light-incident surface of the polarizing plate or the exit-side surface of the substrate 501. .

In the conventional projection type liquid crystal display device, when the amount of light of the light source 1 is increased, the light reflected by the TFT liquid crystal panel causes the display defect. This defect first occurs in the TFT liquid crystal panel 53 that modulates the blue light flux having the light on the short wavelength side. Therefore, the light amount of the light source 1 is
It was necessary to limit the liquid crystal panel 53 to the extent that no problem occurred.

It has been confirmed that, in the projection type liquid crystal display device of the present invention, even if the irradiation illuminance of the TFT liquid crystal panel 53 is about three times as high as the conventional one, the adverse effect of reflected light can be prevented. Therefore, it is possible to irradiate the TFT liquid crystal panel with light having a higher illuminance than before, and it is possible to reproduce a projected image with higher brightness and higher contrast ratio on the screen than before. In the present invention, since a liquid crystal panel that modulates light on the short wavelength side easily causes a problem, by forming the antireflection film only on the exit side polarization plate 63 of the TFT liquid crystal panel 53 that modulates blue light. It is also possible to reduce the cost.

Further, by forming the antireflection film on the incident surface of the dichroic prism, it is possible to prevent light leakage in the TFT element due to the reflected light from the incident surface of the prism. Also in this case, it is possible to reduce the cost by forming the antireflection film only on the incident surface of the dichroic prism on which blue light is incident.

Further, in the above-mentioned embodiments, the case where the TFT is formed on the inner surface of the emission side substrate has been described as an example, but even if the TFT is formed on the inner surface of the incident side substrate, It has the same effect.

Further, a TFT in which a light-shielding film which shields the reflected light from the light emitting side is formed on the inner surface of the substrate of the TFT liquid crystal panel.
Even in a liquid crystal panel, the light-shielding portion cannot be made large in order to improve the aperture ratio.
Easy to reach the FT element. Therefore, even in such a panel, the same effect can be obtained by forming an antireflection film on the emission side surface of the panel substrate, where the wavelength of the light having the minimum reflectance is 400 nm to 500 nm. Obtainable.

In the above embodiments, the TFT liquid crystal panel is used as an example of a TFT liquid crystal panel used as a light valve of a projection display device.
Even in the case of FT liquid crystal panel, there are similar effects,
It is particularly effective in the case of a bright TFT liquid crystal panel whose aperture ratio is as large as possible.

[0044]

As described above, in the projection display device of the present invention, the reflection prevention which exists on the surface of the emission side of the TFT liquid crystal panel where the light having the minimum reflectance exists between 400 nm and 500 nm. Forming a film. Therefore, T
The light reflected from the interface of the emission surface of the FT liquid crystal panel enters the TFT.
Since it is possible to suppress an increase in the leak current, the TFT liquid crystal panel can be irradiated with stronger light. As a result, it is possible to realize a high-quality projected image having high brightness and a high contrast ratio and excellent color reproducibility.

Further, in the TFT liquid crystal panel of the present invention, an antireflection film having a minimum reflectance of 400 nm to 500 nm is formed on the surface of the liquid crystal panel on the emission side. Therefore, it is possible to prevent the interface reflection light on the emission surface of the TFT liquid crystal panel from entering and increase the leak current of the TFT, so that stronger light is emitted to the TFT.
The liquid crystal panel can be illuminated. Accordingly, it is possible to realize a high-quality image having high brightness and a high contrast ratio and excellent color reproducibility. Also, this T
When the FT liquid crystal panel is used as a light valve of a projection display device, it can contribute to high brightness, high contrast, and high quality of the projection display device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical system of a three-plate type projection type liquid crystal display device.

FIG. 2 is an explanatory diagram for explaining a problem of a conventional projection type liquid crystal display device.

FIG. 3 is a diagram showing the wavelength dependence of the light sensitivity of the human eye.

FIG. 4 is a diagram showing wavelength dependence of light absorption coefficient of polysilicon.

FIG. 5 is a schematic configuration diagram showing an optical system of a projection type liquid crystal display device to which the present invention is applied.

FIG. 6 is a diagram showing a reflectance of an emission surface of a liquid crystal panel of a conventional projection type liquid crystal display device.

FIG. 7 is a diagram showing a reflectance of an emission surface of a liquid crystal panel of a conventional projection type liquid crystal display device.

FIG. 8 is a diagram showing the reflectance of the emission surface of the liquid crystal panel of the projection type liquid crystal display device diagram to which the present invention is applied.

FIG. 9 is a diagram showing a cross section of a TFT liquid crystal panel using a coplanar type polysilicon TFT.

FIG. 10: Inverse stagger type amorphous silicon TF
It is a figure which shows the cross section of the TFT liquid crystal panel which used T.

FIG. 11 is a schematic configuration diagram showing an optical system of a projection type liquid crystal display device to which the present invention is applied.

[Explanation of symbols]

 1 Light source 2 Reflector 3 Color separation optical system 31, 32, 71, 72 Dichroic mirror 33, 73 Mirror 4, 41, 42, 43 Incident side polarization plate 5, 51, 52, 53 TFT liquid crystal panel 6, 61, 62, 63 Emitting-side polarization plate 7-color synthesis optical system 8 Projection lens (projection optical system) R1 Interface reflected light

Claims (11)

[Claims] 1. A projection type display device comprising a light source, a liquid crystal panel which modulates an incident light beam from the light source and emits it as an outgoing light beam, and a projection optical means for enlarging and projecting the outgoing light beam on a screen. In the liquid crystal panel, liquid crystal is sealed between a pair of substrates, a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of the one substrate, and the liquid crystal panel is provided outside the substrate on the emission side. A polarizing plate is arranged, and the liquid crystal panel is characterized in that an antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm is formed on the surface of the polarizing plate. Projection display device. 2. A projection display device comprising a light source, a liquid crystal panel that modulates an incident light beam from the light source and emits it as an emitted light beam, and projection optical means for enlarging and projecting the emitted light beam on a screen. In the liquid crystal panel, liquid crystal is sealed between a pair of substrates, a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on an inner surface of the substrate on the emission side, and the outside of the substrate on the emission side. A polarizing plate is disposed on the liquid crystal panel, and the liquid crystal panel has an antireflection film formed on the surface of the polarizing plate and having a wavelength of light having a minimum reflectance between 400 nm and 500 nm. And a projection display device. 3. A projection type display device comprising a light source, a liquid crystal panel which modulates an incident light beam from the light source and emits it as an outgoing light beam, and projection optical means for enlarging and projecting the outgoing light beam on a screen. In the liquid crystal panel, liquid crystal is sealed between a pair of substrates, a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on an inner surface of the one substrate, and an outer surface of the substrate on the emission side. 1. A projection display device, characterized in that an antireflection film having a wavelength of light having a minimum reflectance in the range of 400 nm to 500 nm is formed. 4. A projection display device comprising a light source, a liquid crystal panel that modulates an incident light beam from the light source and emits it as an emitted light beam, and projection optical means for enlarging and projecting the emitted light beam on a screen. In the liquid crystal panel, liquid crystal is sealed between a pair of substrates, a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on an inner surface of the substrate on the emission side, and the liquid crystal panel is provided outside the substrate on the emission side. A projection display device, characterized in that an antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm is formed on the surface. 5. A liquid crystal is sealed between a pair of substrates arranged so as to face each other, and a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of one of the substrates to emit light. In the liquid crystal panel having a polarizing plate on the outer surface of the substrate, an antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm is formed on the surface of the polarizing plate. A liquid crystal panel characterized by: 6. A liquid crystal is sealed between a pair of substrates arranged so as to face each other, and a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of one of the substrates, In a liquid crystal panel in which a polarizing plate is arranged on the outer surface of a substrate, an antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm is formed on the surface of the polarizing plate. Liquid crystal panel characterized by the following. 7. A liquid crystal panel in which liquid crystal is sealed between a pair of substrates arranged to face each other, and a thin film transistor and a pixel electrode connected to the thin film transistor are arranged on the inner surface of one of the substrates. 2. The liquid crystal panel according to claim 1, wherein an antireflection film is present on the outer surface of the one substrate, the antireflection film having a wavelength of light having a minimum reflectance between 400 nm and 500 nm. 8. The thin film transistor according to claim 1, wherein a silicon thin film serving as a channel is formed on an inner surface of the substrate, and a gate electrode is formed on the silicon thin film via a gate insulating film. 5. The projection display device according to any one of 4 to 4. 9. The thin film transistor according to claim 5, wherein a silicon film serving as a channel is formed on the inner surface of the substrate, and a gate electrode is formed on the silicon thin film via a gate insulating film. 8. The liquid crystal panel according to any one of 7 to 7. 10. The thin film transistor according to claim 1, wherein a gate electrode is formed on an inner surface of the substrate, and a silicon film to be a channel is formed on the gate electrode via a gate insulating film. 5. The projection display device according to any one of 4 to 4. 11. The thin film transistor according to claim 5, wherein a gate electrode is formed on the inner surface of the substrate, and a silicon film to be a channel is formed on the gate electrode via a gate insulating film. 8. The liquid crystal panel according to any one of 7 to 7.