JP2902879B2 - LCD projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector, and more particularly, to a liquid crystal projector which achieves good assembly.

[0002]

2. Description of the Related Art In recent years, with the spread and diversification of AV media, high image quality and large screens have been pursued. In particular, experimental broadcasts of clear vision and high vision have begun, and projectors using liquid crystal panels have attracted attention. In the literature,
For example, the Journal of the Institute of Television Engineers of Japan, Vol. 45, no. 2 (1
991) "Liquid crystal projection display" and the like describe these techniques in detail.

FIG. 6 schematically shows a three-plate mirror type optical system. Light from a light source (50) such as a metal halide lamp is reflected by a reflection mirror, a heat ray, an ultraviolet cut filter (5).
1), and reaches the dichroic mirror (52). Here, the dichroic mirror (52) has a function of reflecting or transmitting light in a specific wavelength range, and only blue (B) light is changed by 90 ° and reflected, and other light is transmitted. The transmitted light is incident on the dichroic mirror (53), and only the green (G) light is reflected, and the transmitted light is red (R).
Becomes Thus, B. G. FIG. The lights separated in the order of R are incident on dedicated liquid crystal panels (54), (55), and (56). Each panel (54), (55), (56)
Are provided with polarizers on both sides as shown by solid lines, and images corresponding to each color are reproduced. The incident light is modulated for each color and then synthesized.

[0004] The dichroic mirror (57) reflects the G light and combines it with the transmitted B light, and also combines the R light with the dichroic mirror (58). The combined light is projected on a screen by a projection lens (59). Here, (60) is a condenser lens for narrowing light to the projection lens (59). (61) is a reflection mirror.

On the other hand, a liquid crystal panel is one in which liquid crystal is injected between two glass substrates.
The cells are arranged in a matrix as shown in FIG. First, a gate line (7
A plurality of 1) are provided above and below, and a gate (72) is provided integrally with this line (71). Further, an auxiliary capacitance electrode and an auxiliary capacitance line which partially overlap the display electrode (73) to form an auxiliary capacitance extend. On these layers, a-Si, N ⁺ type a-S is interposed via a gate insulating film.
i and ITO are formed. The gate (72)
An a-Si layer (74) is provided thereon, and an N ⁺ -type a-Si layer (75) indicated by a dotted line is further provided via a semiconductor protective film.
Is provided. In addition, a display electrode (7
3) a gate line (71) and a drain line (7)
6). This display electrode (73)
Is an N ⁺ type a-Si corresponding to the source region of the TFT.
It is electrically connected to a source electrode (78) extending from above the layer (75). On the other hand, a drain electrode (79) is provided on the N ⁺ type a-Si layer (75) corresponding to the drain region of the TFT, and a drain line (76) integrated with the drain electrode (79) is provided. . Further, an alignment film is provided via a passivation film.

On the other hand, a counter electrode, a light-shielding film and an alignment film are provided on a counter substrate, and liquid crystal is injected between the two substrates to form a liquid crystal panel. The TFT substrate on which the TFT is formed and the counter substrate are bonded together with a seal at a fixed gap, and a polarizing plate is bonded so as to sandwich both substrates. Here, specifically, a metal film having a light-shielding function is formed on the counter substrate, except for a region having a size and a position corresponding to the display electrodes (73). Further, a transparent conductive film serving as a counter electrode is formed via an insulating layer.

[0007]

Generally, light entering a liquid crystal panel is converged by a condenser lens (60), so that incident light has a certain slope as shown in x and y degrees in FIG. This causes uneven brightness on the projection screen. For example, when the panel is displayed in black over the entire surface, a whitish portion occurs below the projection screen.

For this reason, as shown in FIG. 8, the liquid crystal panel is inclined to a value of z degrees from a direction perpendicular to the optical axis to prevent this luminance unevenness. Also, in order to make the preferred viewing angle direction of FIG. 8 (a direction parallel to the direction of the turned-on liquid crystal and the direction most visible) and the anti-priority viewing angle direction of FIG. Was provided. That is, the connector terminals C _B and C _R of the B and R liquid crystal panels face the connector terminals C of the G liquid crystal panel toward the front of the drawing.
_G was provided in the opposite direction to the back side of the paper.

[0009] At a 1, when a liquid crystal panel g ₁ is a further specific view of a conventional structure. A large F written in the liquid crystal panel indicates the shape of an image, and a small F indicates the shape of a display area of one pixel. In the liquid crystal panel indicated by S, the TFT substrate is seen in FIG. 1 and the opposite substrate is arranged on the back side. Also, the arrow with the superior or opposite indicates the preferential viewing angle direction or the opposite preferential viewing angle direction. g ₁
Panel, as described above, in order to match the viewing direction, the connector terminal C _G is disposed in a direction opposite to C _B and C _R.

[0010] As described above, because of the coincidence of the luminance unevenness and priority viewing angle, or the connector terminal C _G in the reverse direction, tilted of z of the liquid crystal panel, a problem that complicates the assembly of the liquid crystal projector main body there were. In particular, when the insertion direction of the connector terminal is different, a trouble such as preparing a special insertion jig or inverting the main body by 180 degrees to easily insert the panel occurs.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a light split into R, G, and B lights from a light source is an R-only panel having connector terminals, and a G-only panel. And a liquid crystal projector synthesized by optical means after the incident light is modulated by the panel and is modulated by the panel, and at least the liquid crystal panel g2 dedicated to G, An emission-side transparent substrate, which is one configuration, and two retardation films whose stretching directions are orthogonal to each other are provided between an emission-side polarizing plate adjacent to the transparent substrate and a polarizing axis of the emission-side polarization plate. The angle between the polarizing plate and the stretching axis of the adjacent retardation film is 30 degrees or more.
60 degrees or 120 degrees to 150 degrees, this R, G
This problem can be solved by mounting the connector terminals CR, CG, and CB provided for each liquid crystal panel as signal paths of the liquid crystal panels of FIGS.

Further, the light split into R, G, and B light from the light source is supplied to an R-only panel having connector terminals,
A liquid crystal projector that is incident on a dedicated panel and a panel dedicated to B, and that the incident light is modulated by the panel and then combined by optical means, and all the liquid crystal panels are An output-side transparent substrate, which is one configuration, and two output-side retardation films whose stretching directions are orthogonal to each other are provided between the transparent substrate and the adjacent output-side polarizing plate. The angle between the polarizing plate and the stretching axis of the adjacent retardation film is set to 30 degrees to 60 degrees or 120 degrees to 150 degrees, and the signal paths of the R, G, and B liquid crystal panels become This problem can be solved by mounting the provided connector terminals CR, CG, and CB toward the same side of the liquid crystal projector.

[0013]

The retardation film is composed of an inexpensive polymer film. When the film is uniaxially stretched or anisotropically biaxially stretched, the polymer is oriented in the direction in which the stretching ratio is large, and exhibits optical anisotropy. become. For example, a polyvinyl alcohol or a polycarbonate film is generally used. Two retardation films having the same retardation arranged at a stretching direction of 90 degrees have a retardation of 0 when viewed from the front, and have a retardation when viewed from an oblique direction. When such a retardation film is used for a TN cell as in the present invention, the TN cell enters the TN cell from an oblique direction (anti-priority viewing angle direction) and becomes elliptically polarized light without any change in characteristics from the front. It is possible to reduce the ellipticity of light and perform display with good viewing angle characteristics.

As a result of the experiment, the light transmission axis of the second polarizer and the second
It has been found that luminance unevenness can be further reduced by giving a predetermined angle (C) to the stretching axis of the retardation film. Specifically, when C = 30 ° to 60 ° and 120 ° to 150 °, the transmittance of the black display panel in the anti-priority viewing angle direction can be greatly reduced, and as a result, the unevenness of brightness on the upper and lower sides of the projection screen can be reduced. Can be. Therefore, it is possible to eliminate each z degree of the tilt of the liquid crystal.

Further, when a retardation film is provided on the liquid crystal panel g ₂ dedicated to G, the transmittance can be made substantially the same as that of the R or B panel even though the panel g ₂ is turned upside down. For this reason, color unevenness can be eliminated as before, and z-degree tilting is required due to luminance unevenness. However, it is possible to arrange them in the same direction as the B and R connector terminals.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is to prevent uneven brightness of a liquid crystal panel itself, to improve the projection screen by using the same, and to simplify the assembling work of a liquid crystal projector. It is effective. However, since most of the projectors employ an active matrix, a description will be given here of an a-SiTFT liquid crystal projector.

First, a general TFT substrate will be described with reference to FIG. A plurality of gates (72) formed on a transparent insulating substrate (1), a plurality of gate lines (71) integrated with the gate (72), a plurality of auxiliary capacitance electrodes, and the auxiliary capacitance electrodes (2) A plurality of auxiliary capacitance lines (3) integrated with the gate (72) and the gate line (7).
1) There is an insulating layer (4) covering the auxiliary capacitance electrode and the auxiliary capacitance line.

The gate line (71) and the gate (7
2) is indicated by a dashed line and is composed of about 1500 ° Cr. The gate line (71) extends left and right,
It is provided integrally with the gate (72), and the above configuration is repeated. The auxiliary capacitance line is, for example, approximately 150
It consists of 0% Cr or ITO. Furthermore SiNx or SiO ₂ and the insulating layer made of SiN _X (4) is provided to cover the entire surface of the substrate.

Alternatively, a gate line integral with the gate and an auxiliary capacitance line integral with the auxiliary capacitance electrode may be formed of Al, and the surface thereof may be anodized. In this case, as the size of the screen increases in the future, it contributes to lowering the resistance of the line, and has the effect of forming an anodized insulating layer on the line at a low cost in order to prevent a short circuit with the drain line. . In addition, the non-doped non-single-crystal silicon film (7) stacked on the insulating layer corresponding to the gate (72).
4) and non-single-crystal silicon doped with impurities formed on a non-single-crystal silicon film (74) corresponding to a source region and a drain region of a switching element (TFT) having the gate (72) as one component. There is a film (75) and a display electrode (73) which is provided close to the non-single-crystal silicon film (75) and at least partially overlaps the auxiliary capacitance electrode.

Here, the non-single-crystal silicon film (74) which is not doped with impurities is provided as an active layer on the gate (72), and approximately 1000 ° in a region shown by a two-dot chain line in FIG. A-Si having a thickness of An impurity-doped non-single-crystal silicon film (75) overlapping with the active layer (74) is provided, and here, about 500 ° N ⁺ type a-Si is provided. The display electrode (73) is indicated by a two-dot chain line and has an I
It consists of TO.

A non-single-crystal silicon film (75) doped with an impurity corresponding to the source region and the display electrode (7).
3) a drain electrode (79) electrically connected to an impurity-doped non-single-crystal silicon film (75) corresponding to the drain region, and a drain electrode (79) electrically connecting the drain electrode. (79) and an integrated drain line (76).

The source electrode (78) and the drain electrode (7
9) and the drain line (76) are shown by solid lines and consist of a stack of about 1000 ° Mo and about 7000 ° Al. The source electrode (78) is connected to the ITO through a contact hole, and the drain line (76) extends up and down integrally with the drain electrode (79).

Finally, an alignment film is provided via a passivation film provided on the entire surface. However, the passivation film may be omitted. Although the above configuration does not use the semiconductor protective film used to prevent the non-doped a-Si (74) from being over-etched,
x may be used as a semiconductor protective film.

On the other hand, a counter electrode, a light-shielding film and an alignment film are provided on the counter substrate, and liquid crystal is injected between the two substrates to form a liquid crystal panel. . Here, specifically, a metal film having a light-shielding function is formed on the counter substrate, except for a region having a size and a position corresponding to the display electrodes (73). Further, a transparent conductive film serving as a counter electrode is formed via an insulating layer.

The first feature resides in the structure of the retardation film as shown in FIG. 4. The specific structure will be described below with reference to the drawings. From the bottom, the first polarizing plate (1
0), liquid crystal panel (11), first retardation film (1
2), a second retardation film (13) and a second polarizing plate (14) are arranged, and (15) and (16) are orthogonal to each other on a polarizing axis of the polarizing plate. (17), (1
8) is the orientation direction of the liquid crystal panel, the former being a lower substrate (in principle, a counter substrate) and the latter being an upper substrate (in principle, a TFT substrate). (19) and (20) are the stretching axes of the first retardation film and the second retardation film.

The orientation direction of the liquid crystal panel is substantially 9
It is twisted by 0 degrees, and the stretching axes of the two retardation films are also shifted by 90 degrees. Further, the viewing angle with respect to the polarizing plate is a,
The viewing angle is assumed to be b, and the stretching axis of the second retardation film and the second
An experiment was performed under the following conditions, where the angle of the polarizing plate with respect to the polarization axis was C. The Δn of the liquid crystal is 0.09, the cell gap is 4.6 μm, the voltage applied to the liquid crystal layer is 6 V, and the liquid crystal panel is displayed in black. The angle C was measured in a range of 0 to 180 degrees in steps of 15 degrees. The retardation of the two retardation films was the same, and the retardation was changed from 300 nm by 100 to 800 nm. A is 0
-70 degrees, step 10 degrees, b are 0-360 degrees (18
Zero degree corresponds to b = 0 and 270 degrees corresponds to b = 90 degrees. ), Measured at step 10 degrees.

FIGS. 10 to 15 show several examples of the measurement results of the transmittance at the time of black display. For comparison, FIG. 9 shows a case where no retardation film was provided. The three types of curves shown in FIG. 9 to FIG.
This is a curve when the transmittance is 0.045, 0.030, and 0.005. The horizontal axis represents the viewing angle a, and the values from 0 to 360 shown around indicate the viewing angle b. The liquid crystal panel is provided perpendicular to the optical axis, unlike the conventional liquid crystal panel (FIG. 8), as shown in FIG.

As a result of the experiment, the viewing angle characteristics were greatly changed by changing C, and C was 30 to 60 degrees, and 120 to 120 degrees.
In the range of 150 degrees, the transmittance in the anti-priority viewing angle direction decreased and became favorable when displaying black. Δ of the retardation film
When nd was large, it was particularly good at 600 to 800 nm. This example is shown in FIG. 10 to FIG. 13, and the curve of FIG. 10 shows that a retardation film of Δnd = 600 nm has C = 4.
5 degrees, the curve of FIG. 11 is C = 135 degrees for a retardation film of Δnd = 600 nm, and the curve of FIG. 12 is Δnd =
C = 45 degrees for an 800 nm retardation film, and the curve in FIG. 13 shows that C = 1 for a Δnd = 800 nm retardation film.
It is a curve at the time of 35 degrees.

The direction of b = 90 degrees (270 degrees in the graph) indicates the preferred viewing angle direction, normally white, TN mode LC
When the transmittance in this direction increases in the case of D black display (voltage ON), a white spot occurs at the lower part of the screen in the black display of the liquid crystal projector projection screen. Compared with the conventional method, the method of the present invention has a wider range in which the transmittance in the preferential viewing angle direction is small in black display (voltage ON), and can prevent white spots at the lower part of the screen in black display on the liquid crystal projector projection screen. It is possible.

The above is the description when the retardation film is provided on one liquid crystal panel. This application is the structure of FIG. 4 which employs the retardation film, when adopting the panel g ₂ in FIG. 1, or R, when employed in all panels of G and B, was found to have an effect. At a 1, when a liquid crystal panel g ₂ is a layout view of a liquid crystal panel of a liquid crystal projector of the present application. A large F written in the liquid crystal panel indicates a shape of an image, and a small letter F indicates a shape of a display area of one pixel. In the liquid crystal panel indicated by S, the TFT substrate is seen in FIG. 1 and the opposite substrate is arranged on the back side. In addition, the arrow with the superior or opposite direction is the preferred viewing angle direction (270 degrees in the graph, b = 90 in FIG. 4).
Degrees) or the anti-priority viewing angle direction (90 degrees in the graph, b = 270 degrees in FIG. 4). In the conventional structure without the retardation film, the occurrence of uneven brightness on the upper and lower sides of the panel is indicated by * and 、, and the uneven brightness on the TFT substrate is indicated by *.

Referring to FIGS. 1 and 16, a further specific example will be described. FIG. 16 shows an upper and lower projection screen (*) of a three-plate mirror type liquid crystal projector using three liquid crystal panels.
(Areas marked with ○ and ○) when the retardation film is used only for the G panel (middle row in the table)
And the case where the retardation film is used for all the R, G, and B panels (lower part of the table). However, when using a retardation film of G, g ₂ panels, top, * and lower relationship ○ is reverse. For comparison, those having a conventional structure without using a retardation film are shown in the upper part of the table.

As can be seen from FIG. 8, in order to use the condenser lens (60), the light is narrowed down and x degree and y
Despite having degrees, the actual angles are both 15 degrees.
This depends on the focal length of the condenser lens. The longer the focal length, the smaller the angle, and the shorter the focal length, the larger the angle. In addition, when the retardation film is provided only in the panel of the conventional structure and the panel of G, it is tilted by z degrees (3 degrees) with respect to the direction perpendicular to the optical axis. Degree.

When the transmittance is examined on the basis of this angle, conventionally, the mark * (upper) is 0.005 or less, and the mark 下 (lower) is substantially 0.020. Therefore, the mark * is substantially black, and the mark 若干 is slightly whitish. However, the transmittance is
Since all three sheets are the same, color unevenness does not occur. Then only the panel g ₂ G, then the phase difference film of FIG. 14 ([Delta] nd =
(800 nm, C = 45 degrees) will be described. Here, since the priority viewing-angle direction and anti-preferential viewing direction does not coincide with the other panel, unless using a phase difference film, the upper and lower transmittance differs only g _2, luminance unevenness and color unevenness occurs . However, with the use of the retardation film, the correction is performed as shown by the arrow, so that the color unevenness can be eliminated. However, since brightness unevenness occurs, z degrees (3 degrees)
Must be tilted.

Further, all the panels (the panel of G is g ₂
15) (Δnd = 400n) in FIG.
m, C = 45 degrees), the transmittances are all the same, and color unevenness and luminance unevenness can be eliminated. Therefore, by providing the retardation film, the connector terminals of the G panel can be unified with other panels without deterioration of image characteristics. Actual g ₂ panels, upper and lower luminance unevenness, preferential viewing direction is the opposite not match the panels B and R, as described above, since it has the structure of FIG. 4, a priority viewing-angle direction The distinction of the viewing angle characteristics in the anti-priority viewing angle direction becomes apparent.
Therefore it is possible to match the connector terminals of g ₂ panel and panel B and R, attained the efficiency of assembly work.

Also, the configuration shown in FIG. 4 is adopted for all the panels including the g ₂ panel, and even if the connector terminal of the g ₂ panel is matched with another panel, as described above, the distinction between the preferential viewing angle characteristic and the anti-priority viewing angle characteristic can be made. Since it disappears, the viewing angle characteristic is improved, and furthermore, since the luminance unevenness is eliminated, it is not necessary to incline by z degrees from the direction perpendicular to the optical axis described in FIG. In other words, all the connector terminals can be unified, and the panels can be arranged vertically.

FIG. 2 shows a specific structure when three panels employing a retardation film are arranged in a liquid crystal projector. Since the configuration is almost the same as that of FIG. 6,
The same parts have the same figure numbers. Different place is inserted the retardation film on the liquid crystal panel and polarizing plates, the liquid crystal panel g ₂ of G is only in that provided in the front with respect to the paper surface in the same way as any other panel.

FIG. 3 shows a specific structure when this configuration is employed in a liquid crystal projector. The main body (100) has a liquid crystal panel (5) integrated with the mounting bracket (101).
4), (55) and (56) are attached. The connector terminal is attached to the paper surface in the reverse direction.
Actually, as shown in FIG. 3, the printed circuit boards and metal fittings are not densely arranged as shown in FIG. 3, but the contact terminals of the liquid crystal panel are unified on one side, and if the liquid crystal panel is arranged vertically. However, these printed circuit boards and metal fittings are less subject to restrictions. Further, it is not necessary to rotate the main body (100) by 180 degrees during assembly.

[0038]

As is apparent from the above description, two retardation films whose stretching axes are orthogonal to each other are provided between the liquid crystal panel and the second polarizing plate. By setting the polarization axis and the stretching axis of the adjacent second retardation film to 30 ° to 60 ° and 120 ° to 150 °, the transmittance of the liquid crystal panel set to black display in the anti-priority viewing angle direction is reduced. Since the size can be reduced, the viewing angle characteristics can be made uniform, and when projected on the screen, the uneven brightness at the top and bottom of the screen can be reduced. Therefore, the liquid crystal panel does not need to have a certain angle from the direction perpendicular to the optical axis, and the connector terminals of the liquid crystal panel can be unified and mounted on one side of the liquid crystal projector.

That is, by providing the retardation film only on the panel G, the connector terminals of this panel can be unified with other panels, so that the structure of the main body can be simplified and the assembling work can be simplified. Further, if the retardation films are provided on all the panels, all the connector terminals can be unified, and furthermore, the liquid crystal panels can be arranged vertically to eliminate unevenness in the brightness of the image. Therefore, further simplification and simplification of the assembling process can be achieved.

[Brief description of the drawings]

FIG. 1 is a layout view of a liquid crystal panel used in a liquid crystal projector of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a liquid crystal projector of the present invention.

FIG. 3 is a diagram showing a mounted state of a liquid crystal panel in the liquid crystal projector of the present invention.

FIG. 4 is a configuration diagram of a liquid crystal module used in the liquid crystal projector of the present invention.

FIG. 5 is a diagram showing a relationship between a condenser lens and a panel in FIG. 4;

FIG. 6 is a diagram illustrating an optical system of a conventional liquid crystal projector.

FIG. 7 is a plan view of a liquid crystal display element used in the present application.

FIG. 8 is a diagram showing a conventional configuration corresponding to FIG. 5;

FIG. 9 is a diagram illustrating transmission characteristics of a liquid crystal panel provided with no retardation film.

FIG. 10 is a diagram showing transmission characteristics of the liquid crystal panel of the present invention.

FIG. 11 is a diagram showing transmission characteristics of the liquid crystal panel of the present invention.

FIG. 12 is a diagram showing transmission characteristics of the liquid crystal panel of the present invention.

FIG. 13 is a diagram showing transmission characteristics of the liquid crystal panel of the present invention.

FIG. 14 is a diagram showing transmission characteristics of the liquid crystal panel of the present invention.

FIG. 15 is a diagram showing transmission characteristics of the liquid crystal panel of the present invention.

FIG. 16 is a diagram showing characteristics of the retardation film when used properly.

[Explanation of symbols]

 (10) First polarizing plate (11) Liquid crystal panel (12) First retardation film (13) Second retardation film (14) Second polarizing plate

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1335 510 G02F 1/13 505

Claims (2)

(57) [Claims] 1. Light split into R, G, and B light from a light source is incident on an R-only panel, a G-only panel, and a B-only panel having a connector terminal. A liquid crystal projector synthesized by optical means after being modulated by a panel, wherein at least G
The dedicated liquid crystal panel has two retardation films whose stretching directions are orthogonal to each other between a transparent substrate on the output side, which is one configuration of the liquid crystal panel, and a polarizing plate on the output side, which is adjacent to the transparent substrate. The angle between the polarizing axis of the polarizing plate on the output side and the stretching axis of the retardation film adjacent to the polarizing plate is set to 30 to 60 degrees or 120 to 150 degrees. path and Do Ri each liquid signals of each liquid crystal panel
LCD projector connector terminals provided for each crystal display panel, was characterized in that the mounted towards the same side of the liquid crystal flop <br/> Rojeku data. 2. The light split into R, G, and B light from a light source is incident on an R-only panel, a G-only panel, and a B-only panel having a connector terminal. A liquid crystal projector synthesized by optical means after being modulated by a panel, wherein all the liquid crystal panels have an emission side transparent substrate which is one configuration of the liquid crystal panel, and an emission side adjacent to the transparent substrate. The two retardation films whose stretching directions are orthogonal to each other are provided, and the angle between the polarization axis of the polarizing plate on the output side and the stretching axis of the retardation film adjacent to this polarizing plate is 30 degrees. ~ 60 degrees or 120 ~ 150 degrees, this R, G and B
Each liquid crystal panel of, your Ri Do the path of the signal to each of the liquid crystal panel
Connector terminals arranged on bets is the same of the liquid crystal projector
A liquid crystal projector that is mounted facing one side .