JPH0664420B2 - Projection type liquid crystal display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type liquid crystal display device, and more particularly to a projection type liquid crystal device for projecting and displaying an image displayed by a liquid crystal display device on a light reflection screen. Regarding display device.

2. Description of the Related Art FIG. 3 is a block diagram showing the configuration of a liquid crystal display device 1 according to the prior art. The liquid crystal display device 1 is configured to include a projector 2 and a screen 11, and in the projector 2, the light L from the light source 3 is forwarded (third by the reflecting mirror 10).
Toward the left side of the drawing), the light is condensed by the condenser lens 4, passes through the heat ray absorbing filter 5, blocks heat rays, passes through the first polarizing plate 6, becomes linearly polarized light, and then passes through the liquid crystal display element 27. Then, it is subjected to optical rotation modulation according to the display content to be displayed, and then the second polarizing plate 28 forms a luminance pattern according to the display content, which is enlarged by the projection lens 9 to the outside (second
The screen 11 on the left side of the figure is irradiated.

The screen 11 is formed of a sheet material 12 such as vinyl chloride and a reflective sheet 13 such as aluminum that covers the surface of the sheet material 12. The image projected from the projector 2 onto the screen 11 is reflected by the reflective sheet 13. , Observed.

However, in the projection type liquid crystal display device 1 as described above according to the prior art, a high contrast screen is displayed in an environment in which light entering the screen 11 from the surroundings is zero, such as a dark room. Although it is obtained on the screen 11, when the surroundings are bright, such as in a normal room, the contrast of the screen of the screen 11 is significantly reduced due to the influence of ambient light incident on the screen 11, and the screen is difficult to see. It was

In particular, when the display device 1 is a projection type liquid crystal display device capable of color display, a mosaic-shaped R corresponding to display pixels is used.
The three-color filters of (red), G (green), and B (blue) are arranged in parallel, and the light intensity of the transmitted light is remarkably reduced, so that the influence of ambient light appears more remarkably.

Therefore, the object of the present invention is to
It is an object of the present invention to provide a projection type liquid crystal display device in which the deterioration of the contrast of an image displayed on a light reflection screen is significantly reduced and the image quality is improved.

Means for Solving the Problems The present invention includes a liquid crystal display element 28 and a first polarizing means 27, and a projection unit 22 that polarizes and projects the display content of the liquid crystal display element 28, and a projected image from the projection unit 22. Is a projection-type liquid crystal display device including a light reflection screen 31 on which the light reflection screen 31 is displayed. Sheet 34 and second polarizing means 35, 35a
Is a projection type liquid crystal display device characterized in that

Operation The liquid crystal display device according to the present invention obtains linearly polarized light by the first polarizing means, transmits the light through the liquid crystal display element, modulates the polarized light according to the display content, and irradiates the light reflection screen.

A second polarization means is formed on the surface of the light reflection screen, and all the incident light from the projection unit is reflected and observed through the second polarization means, and the light incident from the surroundings is about 1 of the light quantity. / 2 is blocked by the second polarizing means.

Further, according to the present invention, the sheet 34 is provided on the reflecting surface 33, and the sheet 34 is subjected to the lenticular processing in the vertical direction to form the light scattering layer having a plurality of sag shapes. The strongest ambient light C (see FIG. 1 and FIG. 4) can be reflected as if hitting a mirror surface, which allows the sheet 34 with strong vertical direction to be used under indoor lighting. The contrast ratio can be further improved.

Embodiment FIG. 1 is a block diagram showing an optical configuration of a projection type liquid crystal display device 21 according to an embodiment of the present invention. The light L1 from the light source 23 is condensed by the condenser reflecting mirror 25 and the condenser lens 24, becomes light L2 directed to the left in FIG. 1, passes through the heat ray absorption filter 26, and the heat ray is blocked.
The heat generation due to is suppressed.

The light L3 that has passed through the heat ray absorption filter 26 is a polarization means, and has less heat loss and less polarization loss than the polarization plates 6 and 8 used in the prior art.
S4 polarization component L4 which is incident on and goes upward in FIG.
Then, it is separated into two linearly polarized light components orthogonal to each other of the P polarized light component L5 directed to the left in FIG. P polarization component is 9
The light L6, which is incident on the nematic liquid crystal display element 28 that is twisted by 0 degree, is modulated in polarization characteristics according to the display content of the liquid crystal display element 28, and the modulated light L6 is magnified by the projection lens 29 and is indicated by reference numeral A. The light reflection screen 31 is illuminated along the route.

The light reflection screen (hereinafter referred to as screen) 31 is
For example, the surface of a sheet material 32 such as vinyl chloride (PVC) is coated with aluminum or the like to form a reflecting surface 33, and the reflecting surface 33 is subjected to lenticular processing in the vertical direction of the screen 31 so as to have a plurality of sagging shapes. The sheets 34 on which the light scattering layers are formed are stacked to suppress the scattering of the reflected light in the vertical direction of the screen 31. Sheet 34
A polarizing plate 35 is further attached to the surface of the. The polarizing plate 35 polarizes in a direction perpendicular to the plane of the drawing.

The light that enters the projection unit 22 or the screen 31 and is reflected by the reflection surface 33 is observed through the polarizing plate 35. At this time, since the light projected from the projection unit 22 is polarized,
Although observed through the polarizing plate 35 as it is, about 50% of the ambient light C incident from the periphery of the screen 31 as indicated by the broken line is blocked by the polarizing plate 35 and is blocked. That is, the influence of the ambient light C is reduced by about 1/2 as compared with the prior art.

Here, the maximum brightness obtained on the screen 31 when the ambient light is zero is B ₀ and the minimum brightness is B ₁ , and the screen 31
Assuming that the brightness of the ambient light incident on B ₃ is B ₃ , the contrast when the ambient light is zero is the same as that of the screen 11 according to this embodiment, even in the screen 11 according to the prior art shown in FIG.
In is also a both equally B ₀ / B _1, if the ambient light luminance _{B 3} is incident, in the contrast prior _{art, (B 0 + B 3)} / (B 1 + B 3) ...... (1) Is. On the other hand, since in this embodiment the ambient light is reduced to 1/2, the _{(B 0 + B 3/2} ) / (B 1 + B 3/2) ...... (2). Therefore, in order to compare the present embodiment with the prior art, the second formula is removed by the first formula, and in the presence of ambient light, the present embodiment has a higher contrast than the prior art. It is doubled and the screen becomes easier to see.

FIG. 2 is a graph showing a comparison of the contrast between this embodiment and the prior art. In the graph, the horizontal axis is the ratio B ₃ / B of the brightness B ₃ due to ambient light and the maximum brightness B ₀ obtained from the projection unit 22.
_{The value 0} is taken, and the vertical axis indicates the display contrast on the screen 31. A curve K1 represented by a solid line is the present embodiment,
The curve K2 represented by a broken line represents the prior art. For example, the ratio of the ambient light and the brightness obtained from the projection unit 22 is 1:10,
That is, when ambient light is incident on the screen 31 with a brightness of 1/10, the contrast obtained in the prior art is less than 10 in the prior art, and about 15 in this embodiment. Further, even when the ambient light and the light from the projection unit 22 are 1: 2, the contrast ratio is remarkably good, and it is shown that the display contrast is remarkably improved as compared with the prior art.

In the embodiment described with reference to FIG. 1 above, the screen 31, the beam splitter 27, and the light source 23 are arranged in a straight line, but as another embodiment of the present invention,
FIG. 4 shows a configuration in which the light source 23 that emits light is arranged at a right angle to the optical axis to the screen 31. The S-polarized component L4 is made incident on the liquid crystal display element 28 from the beam splitter 27. At this time, the polarization direction of the polarizing plate 35a is the fourth
It is the vertical direction of the paper surface of the figure. Corresponding parts of the previous embodiments are designated by the same reference numerals.

As described above, according to the present invention, the light from the light source is condensed,
Linearly polarized light is obtained by the first polarization means 27 with little light loss and excellent heat resistance, transmitted through the liquid crystal display element 28, the above-mentioned polarized light is modulated according to the display content, and the light reflection screen 31 is irradiated.

The light reflecting screen 31 has second polarizing means 35 and 35a formed on the reflecting surface 33, and almost all of the light incident from the projection unit 22 is reflected through the second polarizing means 35 and 35a. Approximately ½ of the light incident from the surroundings is blocked by the second polarization means 35 and 35a.

As a result, even in a bright room, the influence of ambient light is greatly reduced, and a high quality image in which the contrast of a desired screen displayed on the light reflection screen 31 is significantly improved can be obtained. Will be realized.

Further, according to the present invention, the sheet 34 is provided on the reflecting surface 33, and the sheet 34 is subjected to the lenticular processing in the vertical direction to form the light scattering layer in the shape of a plurality of sags. Then, when the strongest ambient light is incident obliquely from above, the light can be reflected as if it hit a mirror surface, and such a screen 34 having a strong directivity in the vertical direction is used. By using the two polarization means 35 and 35a together, the contrast ratio under room illumination can be significantly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an optical configuration of a projection type liquid crystal display device 21 according to an embodiment of the present invention, FIG. 2 is a graph showing the contrast between this embodiment and the prior art, and FIG. FIG. 4 is a block diagram showing the configuration of a projection type liquid crystal display device 1 according to the prior art, and FIG. 4 is a block diagram of another embodiment of the present invention. 1, 21 ... Projection type liquid crystal display device, 2, 22 ... Projection unit, 3, 23 ... Light source, 4, 24 ... Condensing lens, 5,
26 ... Heat ray absorption filter, 6, 8, 35 ... Polarizing plate,
9, 29 ... Projection lens, 11, 31 ... Light reflection type screen, 13, 33 ... Reflecting surface, 34 ... Scattering layer

Claims (1)

[Claims] 1. A projection section 22 which includes a liquid crystal display element 28 and a first polarization means 27 and which polarizes and projects the display contents of the liquid crystal display element 28, and light reflection on which a projection image from the projection section 22 is displayed. 1. A projection type liquid crystal display device including a screen 31, wherein the light reflection screen 31 includes a sheet 34 in which a lenticular processing is performed in a vertical direction on a reflection surface 33 to form a light scattering layer having a plurality of scallops. Second polarization means 35, 35a
A projection type liquid crystal display device, characterized in that: