JPH0659234A - Projection type liquid crystal display - Google Patents

Abstract

PURPOSE:To improve the display quality of the projection type liquid crystal display which enlarges and projects an image on a screen by using a liquid crystal panel by suppressing a ghost due to incident light from a position distant from the optical axis of a projection lens or disabling the ghost to be generated. CONSTITUTION:Between a light source and the projection lens 2 to the screen 5, a condenser lens 3, a polarizer P, the liquid crystal panel Lp, and an analyzer A are arranged in order from the light source side; and the optical axis a2 of the projection lens 2 is not aligned with the optical axis a3 of the condenser lens 3. In this projection type liquid crystal display of a non-optical-axis projection optical system, the analyzer A is arranged slantingly to the surface of the liquid crystal panel Lp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type liquid crystal display for enlarging and projecting an image on a screen using a liquid crystal panel. For a color liquid crystal display device suitable for a projection type liquid crystal display, a three-plate type or one color LCD is used, in which each light separated into three primary colors by a dichroic mirror is modulated by a liquid crystal panel and projected on a screen by a projection lens. A single plate type is known.

[0002]

2. Description of the Related Art FIG. 6 is a side view showing the whole of a conventional three-panel projection type liquid crystal display. As shown in the drawing, dichroic mirrors D1 to D4 and total reflection mirrors M1 and M2 for color separation / composition are shown. Are arranged at a predetermined position and at a predetermined angle with respect to the incident light L from the light source 1.

Three liquid crystal panels Lp1 to Lp3 are arranged perpendicularly to the transmitted / reflected light from the dichroic mirrors D1 and D2 and the total reflection mirror M1. Further, polarizers (polarizers) P1 to P3 are arranged in front of the respective liquid crystal panels Lp1 to Lp3, and analyzers (analyzers) A1 to A3 are arranged behind them. Further, condenser lenses 31 to 33 are arranged in front of the respective polarizers P1 to P3.

In this device, the incident light L from the light source 1
Is reflected / transmitted by the two dichroic mirrors D1 and D2 and is split into the three primary colors R, G, and B, and the condenser lenses 31 to 31
After passing through 33 and the polarizers P1 to P3, they enter the dedicated liquid crystal panels Lp1 to Lp3, and are modulated for each color. Each image after modulation is transmitted through the analyzers A1 to A3,
It is combined by two dichroic mirrors D3 and D4 and projected on the screen 5 by the projection lens 2.

By the way, depending on the difference in the installation method of such a projection type liquid crystal display, there are a floor installation type as shown in FIG. 7, a ceiling installation type as shown in FIG. 8 and a screen center installation type as shown in FIG. It is divided into

As shown in FIG. 9A, when the projection type liquid crystal display 9 is installed at the same height as the center of the screen 5, the optical axis a2 of the projection lens 2 is set as shown in FIG. 9B.
And the optical axis a3 of the condenser lens 3 are coincident with each other and are perpendicular to the surface of the screen 5. Then, since the optical axis a3 of the condenser lens 3 is projected so as to be located at the center of the screen 5, the image on the screen 5 has an optical axis a3.
However, the display quality is relatively good.

[0007]

On the other hand, as shown in FIG.
As shown in (a), when the projection type liquid crystal display 4 is installed on the floor 6, the optical axis a2 of the projection lens 2 is
It is close to the installation floor 6. Looking at the optical system of this projection type liquid crystal display for one liquid crystal panel, FIG.
become that way. That is, since the condenser lens 3 is tilted upwards, the condenser lens 3 is inclined with respect to the optical axis a2 of the projection lens 2.
Has an optical axis a3 inclined to form a non-optical axis projection optical system.

Therefore, the light (hereinafter abbreviated as "outer incident light") L1 which is incident from the position farthest from the optical axis a2 of the projection lens 2 is the condenser lens 3, the polarizer P, the liquid crystal panel Lp,
The light passes through the analyzer A and the projection lens 2 and becomes the transmitted light L1 ′. On the other hand, since the outside incident light L1 is obliquely incident on the analyzer A, a part of the incident light L1 is reflected by the analyzer A to be reflected light L2 and further reflected by the liquid crystal panel Lp. L3 passes through the analyzer A and the projection lens 2 and becomes reflected light L3 '.

Although the reflected light L3 'has a weak light intensity, it appears as a ghost because it is imaged at a position deviated from the image by the transmitted light L1', and the display quality is significantly deteriorated. If the analyzer A is brought into close contact with the surface of the liquid crystal panel Lp, such a problem due to the reflected lights L2 and L3 can be avoided, but since the polarizing plate has a property of absorbing light, if the close contact is made, the analyzer A and the polarized light are polarized. The temperature of the child P rises and the characteristics deteriorate. Therefore, the polarizer P and the analyzer A are normally arranged at a distance of several mm from the liquid crystal panel Lp, and as a result, the light reflected by the analyzer A causes the above-mentioned ghost problem.

This ghost is caused by the optical axis a2 of the projection lens 2.
It becomes larger as it gets away from
In a region close to, even if a part of the incident light L4 is reflected by the analyzer A and is again reflected by the surface of the liquid crystal panel Lp, this reflected light has almost the same optical path as the transmitted light component L4 ′ of the incident light L4. The ghost is inconspicuous because it passes through.

Also in the case of the projection type liquid crystal display 7 of the type installed on the ceiling 8 as shown in FIG. 8A, since the condenser lens 3 is tilted downward as shown in FIG. 8B,
The optical axis a3 of the light source light is inclined with respect to the optical axis a2 of the projection lens 2, and the reflected light L2 and L3 causes the above-mentioned ghost problem.

On the other hand, when the projection type liquid crystal display 9 is installed at the center position of the screen as shown in FIG. 9, the optical axis a3 of the light source coincides with the optical axis a2 of the projection lens 2, and the outside incident light L1 Since the incident angle δ on the analyzer A is larger than that of the optical system of FIGS. 7 and 8, the amount of deviation between the image of the transmitted light component of the outside incident light L1 and the image of the reflected light ray L3 ′ is small. , Ghost is relatively inconspicuous.

The technical problem of the present invention is to pay attention to such a problem in the conventional projection type liquid crystal display of the non-optical axis optical system, and to consider the ghost caused by the incident light from the position apart from the optical axis of the projection lens. To suppress or prevent the occurrence of the error and improve the display quality.

[0014]

FIG. 1 is a side view showing the basic structure of the present invention. The present invention includes a light source and a screen 5
From the light source side to the condenser lens 3,
The polarizer P, the liquid crystal panel Lp, and the analyzer A are arranged in this order, and the optical axis a2 of the projection lens 2 and the optical axis of the condenser lens 3 are arranged.
This is intended for non-optical axis projection type liquid crystal displays that do not match a3.

According to a first aspect of the invention, in the projection type liquid crystal display of such a non-optical axis optical system, the analyzer A is arranged so as to be inclined with respect to the surface of the liquid crystal panel Lp.

According to a second aspect of the invention, as shown in FIG. 2, in the projection type liquid crystal display of the non-optical axis optical system as described above, the light L1 incident from a position farthest from the optical axis a2 of the projection lens 2 is incident. The analyzer A is disposed so as to be inclined by an angle θ with respect to the liquid crystal panel Lp so that the incident angle δ of the light on the analyzer A approaches a vertical direction.

According to the third aspect of the invention, as shown in FIG. 3, the light L3 which is incident from a position farthest from the optical axis a2 of the projection lens 2 and which is reflected by the surfaces of the analyzer A and the liquid crystal panel Lp is: The analyzer A for the outside incident light L1 so that it does not enter the projection lens 2.
The analyzer A is arranged so as to be inclined by an angle β with respect to the liquid crystal panel Lp in a direction in which the incident angle δ on the liquid crystal panel Lp becomes smaller.

[0018]

In the projection type liquid crystal display of the non-optical axis optical system as described in claim 1, the analyzer A is disposed so as to be inclined with respect to the surface of the liquid crystal panel Lp, and the outside incident light L1 is directed to the analyzer A. By controlling the incident angle δ, it is possible to suppress a ghost and to reflect the reflected light from the analyzer A and the liquid crystal panel surface.
The ghost can be disabled by diverting to the outside of.

According to the second aspect of the invention, as shown in FIG. 2A, the analyzer A is parallel to the main surface of the condenser lens 3, that is, parallel to the liquid crystal panel Lp. Position A
Since the analyzer A is arranged so as to be inclined with respect to the liquid crystal panel Lp by an angle θ with respect to 〃, the incident angle δ of the outside incident light L1 to the analyzer A approaches the plane of the analyzer A, and As a result, ghost is suppressed.

As shown in FIG. 2 (b), the analyzer A
However, by further inclining the analyzer A toward the liquid crystal panel Lp so as to pass the position parallel to the main surface of the condenser lens 3 shown in FIG. The incident angle δ of the light L1 on the analyzer A approaches vertical. As a result, the ghost due to the reflected light component of the outside incident light L1 can be further improved.

Contrary to claim 2, in claim 3, the angle β with respect to the analyzer position A 〃 which is parallel to the liquid crystal panel Lp in the direction in which the incident angle δ of the outside incident light L1 on the analyzer A becomes smaller. However, since the analyzer A is arranged so as to be inclined with respect to the liquid crystal panel Lp, the light L3 reflected by the analyzer A and the liquid crystal panel Lp is
Are reflected to the outside of the projection lens 2. Therefore, the reflected light L3 does not enter the projection lens 2, and the problem of ghost does not occur.

[0022]

EXAMPLES Next, practical examples of how the projection type liquid crystal display according to the present invention is embodied will be described. The invention according to claim 1 is characterized in that the analyzer A is inclined with respect to the liquid crystal panel Lp in any direction and at any angle. Then, the configuration in which the incident angle δ of the outside incident light L1 on the analyzer A is inclined so as to approach the vertical is Claim 2, and conversely, the configuration in which the incident angle δ is inclined in the direction in which the incident angle becomes smaller is Claim 3.

Next, the reason why the ghost is suppressed in the configuration of FIG. 2 will be described in detail. In the case of FIG. 2A, since the analyzer A is parallel to the main surface of the condenser lens 3, the incident angle δ of the outside incident light L1 to the analyzer A is as shown in FIG. It becomes larger than the configuration, and approaches the plane of the analyzer A perpendicularly.

As a result, the image of the transmitted component L1 'of the outside incident light L1 and the light L3 reflected by the analyzer A and the liquid crystal panel Lp.
The amount of deviation from the image L3 ′ of is reduced, and ghost is suppressed. When the inclination angle between the condenser lens 3 and the liquid crystal panel Lp is about 5 °, the inclination angle between the liquid crystal panel Lp and the analyzer A is set to about several degrees (for example, about 5 °).

On the other hand, in the case of FIG. 7B, the projection lens 2
The incident light L4 on the optical axis a2 is incident perpendicularly to the analyzer A, so that no ghost occurs at all, but when the analyzer A is tilted as shown in FIG. Since the incident light of the light L4 on the analyzer A is not perpendicular, a ghost is generated by the light reflected by the surfaces of the analyzer A and the liquid crystal panel Lp. However, compared with the incident angle δ of the outside incident light L1, the incident angle of the incident light L4 on the optical axis a2 is close to vertical,
Ghosts are inconspicuous.

On the other hand, in FIG. 2B, the analyzer A is tilted more than in the case of FIG. 2A, and the incident angle δ of the outside incident light L1 is increased.
Is closer to the vertical. When the incident angle δ is tilted to be vertical, there is no ghost due to the outside incident light L1, but the reflected components L5 and L6 of the incident light L4 on the optical axis a2.
The ghost due to.

Therefore, by comprehensively considering the extent of the ghost due to the outside incident light L1 and the extent of the ghost due to the incident light L4 on the optical axis a2, the incident angle δ of the outside incident light L1 and the incident light L4 on the optical axis a2. The inclination angle θ of the analyzer A is set so that the incident angle of is optimal, so that the ghost is most inconspicuous on the entire screen.

Next, FIG. 3 shows that the analyzer A is set to the outside incident light L1.
The angle of incidence δ of becomes smaller,
In the figure (a), both the reflected light L3 of the outside incident light L1 and the reflected light component L6 of the incident light L4 on the optical axis a2 are largely inclined so as to deviate from the projection lens 2, while the figure (b) is shown. Reduces the tilt angle β so that only the reflected light L3 of the outside incident light L1 deviates from the projection lens 2.

First, when the tilt angle β is increased as shown in FIG. 3A, the outside incident light L1 is reflected by the analyzer A like L2 and L3, and then the projection lens 2 is reflected by the liquid crystal panel Lp.
Is reflected to the outside of.

Further, the incident light L4 on the optical axis a2 also has an incident angle to the analyzer A which is not vertical and is incident obliquely.
As indicated by 5 and L6, the light is reflected to the outside of the projection lens 2 by the analyzer A and the liquid crystal panel Lp. At this time, the LCD panel Lp
Depending on the size of, the light may be reflected to the outside of the liquid crystal panel Lp by the analyzer A like L51.

Thus, the reflected light component L3 of the outside incident light L1
Also the reflected light component L6 of the incident light on the optical axis a2
Since it is not incident on, there is no problem of ghost. (B)
In the case of the figure, the inclination angle β of the analyzer A is made small so that the reflected light component L3 of the outside incident light L1 barely deviates from the projection lens 2. As a result, the incident angle of the incident light L4 on the optical axis a2 to the analyzer A becomes nearly vertical, and the amount of deviation between the image L6 ′ of the reflected light component L6 and the image L4 ′ of the transmitted light component is extremely small, Ghosts are inconspicuous.

Although FIGS. 1 to 3 show an optical system taking a floor-standing system as an example, as shown in FIG. 4, even when it is applied to a ceiling-mounted system, it is relative to the optical axis a2 of the projection lens 2. The outside incident light L1 is only inverted by 180 degrees, which is basically the same. Incidentally, FIG. 4 corresponds to FIG. 2A and shows an example in which the analyzer A is tilted with respect to the liquid crystal panel Lp so as to be parallel to the main surface of the condenser lens 3, but FIG. b) and FIG.
Like (a) and (b), it can be tilted in any direction and at any angle.

In each of the above embodiments, only the ghost in the vertical direction of the screen is targeted, but the idea of the present invention is applied to the ghost in the horizontal direction as well, and the analyzer A is tilted left and right with respect to the liquid crystal panel surface. By doing so, it is possible to control the ghost in the horizontal direction of the screen.

Further, according to the same idea, even in the type in which the projection type liquid crystal display is installed at the height of the center of the screen as shown in FIG. 9, by tilting the analyzer A vertically or horizontally with respect to the liquid crystal panel Lp. It is also possible to control the vertical or horizontal ghost on the screen.

FIG. 5 is a side view showing an example in which the idea of the present invention is applied to each of the liquid crystal panels Lp1 to Lp3 of the three-plate projection type liquid crystal display as shown in FIG. That is, the analyzers A1 to A3 next to the respective Lp1 to Lp3 are arranged tilted with respect to the liquid crystal panel surface according to the concept of the present invention.

For example, in the case of the next analyzer A1 of the liquid crystal panel Lp1 for blue color, the configuration of FIG. 2A is implemented, and the optical axis of the condenser lens 31 is located at the center of the screen 5. The analyzer A1 is inclined with respect to the liquid crystal panel Lp1 so as to be parallel to the main surface of the condenser lens 3.

In the case of the next analyzer A2 of the liquid crystal panel Lp2 for green, the configuration of FIG. 2B is implemented, and the analyzer A2 is tilted further than the analyzer A1 for blue, and the analyzer A2 with respect to the analyzer A2. By setting the incident angle so that the incident light on the optical axis a2 of the projection lens 2 is equal to the incident light on the outside, it is possible to uniformly control the ghost in each part.

In the case of the next analyzer A3 of the liquid crystal panel Lp3 for red, the configuration of FIG. 3A is implemented, and the light reflected by the analyzer A3 and the liquid crystal panel Lp3 is reflected by the projection lens 2. In order not to enter, the analyzer A3, the analyzer A1, A2
It is tilted in the opposite direction. Therefore, no ghost occurs.

As described above, the three liquid crystal panels Lp1 to Lp
The analyzers A1 to A3 of p3 can be separately tilted in a predetermined direction and at a predetermined angle. Further, in this embodiment, the idea of the present invention is applied to all the analyzers A1 to A3. However, among the three primary colors, only the green and red liquid crystal panels, which have high brightness and are easily noticeable on the screen 5, are analyzed. It is possible to suppress the ghost only for the color having high brightness by tilting.

[0040]

As described above, according to the present invention, an image of transmitted light and an image of reflected light can be obtained by adjusting the mounting angle of the analyzer with respect to the liquid crystal panel surface without requiring any special parts. Deviation can be suppressed so that the ghost is not noticeable, and the display quality is improved.

That is, as in claim 2, the outside incident light
By tilting the analyzer A in a direction in which the incident angle δ of L1 on the analyzer A approaches a vertical direction, it is possible to suppress a ghost caused by the light L1 incident from a position away from the optical axis a2 of the projection lens.

Contrary to claim 2, the analyzer A is tilted in a direction in which the incident angle δ of the outside incident light L1 on the analyzer A becomes smaller, so that it is farthest from the optical axis a2 of the projection lens 2. The reflected light of the light L1 incident from the different position can be diverted from the projection lens 2 so that the ghost cannot be generated.

[Brief description of drawings]

FIG. 1 is a side view showing the invention of claim 1. FIG.

FIG. 2 is a side view showing the invention of claim 2;

FIG. 3 is a side view showing the invention of claim 3;

FIG. 4 is a side view showing an example in which the present invention is applied to a ceiling-mounted projection type liquid crystal display.

FIG. 5 is a side view showing an example in which the present invention is applied to each liquid crystal panel of a three-plate type projection liquid crystal display.

FIG. 6 is a side view showing a conventional three-panel projection type liquid crystal display.

FIG. 7 is a side view showing a conventional floor-standing projection type liquid crystal display.

FIG. 8 is a side view showing a conventional ceiling-mounted projection type liquid crystal display.

FIG. 9 is a side view showing a projection type liquid crystal display with a screen center installed.

[Explanation of symbols]

 1 Light source L Light emitted from light source 2 Projection lens a2 Optical axis of projection lens 3 Condenser lens a3 Optical axis of condenser lens D1 to D4 Dichroic mirrors M1 and M2 Total reflection mirrors Lp1 to Lp3 Liquid crystal panel P, P1 to P3 Polarized light Child A, A1 to A3 Analyzer L1 Outside incident light L4 Incident light on the optical axis of the projection lens 4 Floor-standing projection liquid crystal display 5 Screen 6 Floor 7 Ceiling-mounted projection liquid crystal display 8 Ceiling 9 Screen center installation Type projection LCD

Claims (3)

[Claims] 1. A light source and a projection lens for a screen (5)
Between (2) and the light source side, condenser lens (3), polarizer (P)
The LCD panel (Lp) and the analyzer (A) are arranged in this order, and the optical axis (a2) of the projection lens (2) and the optical axis (a3) of the condenser lens (3) are arranged.
In a projection-type liquid crystal display with a non-optical axis projection optical system, the analyzer (A) is tilted with respect to the surface of the liquid crystal panel (Lp). . 2. The incident angle (δ) of the light (L1) incident from the position farthest from the optical axis (a2) of the projection lens (2) on the analyzer (A).
Position parallel to the LCD panel (Lp) so that
At the angle (θ) with respect to A〃), the analyzer (A) is the liquid crystal panel.
The projection type liquid crystal display according to claim 1, wherein the projection type liquid crystal display is disposed so as to be inclined with respect to (Lp). 3. Light incident on the projection lens (2) at a position farthest from the optical axis (a2) and reflected by the analyzer (A) and the liquid crystal panel (Lp) surface is reflected by the projection lens (2). In order to prevent the light from entering the LCD panel (2), the light (L1) entering from the position farthest from the optical axis (a2) of the projection lens (2) enters the liquid crystal panel ( Lp) and the parallel position (A〃) with respect to the angle (β
2.) The projection type liquid crystal display according to claim 1, wherein the analyzer (A) is disposed so as to be inclined with respect to the liquid crystal panel (Lp).