JP3277927B2 - Projection type liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a projection type liquid crystal display device. More specifically, the present invention relates to a multi-panel projection type liquid crystal display device using a plurality of TN positive type liquid crystal display elements.

[0002]

2. Description of the Related Art In a conventional projection type liquid crystal display device,
Using a liquid crystal display element with a small cell thickness unevenness (0.35 to 0.45 in Δnd), after switching the separated light from the light source, photosynthesize again by the optical system, and obtain an enlarged projected image by the enlarged projection system. Was something.

[0003]

However, in the prior art, since the allowable range of the cell thickness unevenness is narrow, the yield is lower than that of a single-panel projection type liquid crystal display device using only one liquid crystal display element. In addition, since the cell thicknesses are not uniform, there is a problem that color unevenness occurs in the projected image after synthesis.

Therefore, the present invention solves such a problem, and an object of the present invention is to make the cell thickness unevenness of the TN positive type liquid crystal display element uniform, thereby widening the allowable range of the cell thickness unevenness and increasing the yield. Therefore, there is a need to obtain a projection-type liquid crystal display device which is inexpensive and has high image quality by eliminating the color unevenness of the projected image.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and uses a plurality of liquid crystal display elements after separating light from a light source by an optical system. In the projection type liquid crystal display device in which the optical switching is performed and the light is again synthesized by the optical system to obtain an enlarged projection image by the enlargement projection system, the cell thickness unevenness of the plurality of liquid crystal display elements is larger than the cell thickness of the peripheral portion. The liquid crystal display device is characterized in that the central portion has a large cell thickness, and the plurality of liquid crystal display elements have uniform cell thickness levels at the central portion.

[0006]

[0007]

[0008]

[0009]

[0010]

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

Embodiment 1 FIG. 1 is a sectional view of a TN positive type liquid crystal display device.

First, polysilicon TFTs, pixel electrodes, data lines, and scanning lines are formed in a matrix on the transparent substrate 1 as switching elements.

Next, a light shielding layer and a common electrode are formed on the transparent substrate 2.

Next, a transparent substrate 1 on which a polysilicon TFT or the like is formed and a transparent substrate 2 on which a common electrode or the like is formed
After orientation treatment to 0 °, sealing agent 4 mixed with glass fiber having a fiber diameter of 4.0 μm as spacer 3
Is formed on the transparent substrate 1 by screen printing or dispenser coating and the like, and is bonded while performing alignment, and is pressed. When a predetermined cell thickness is obtained, the sealant 4 is cured, and Δn = 0.1 Is sealed.

Next, after cutting into a predetermined shape, the polarizing plate 6 was adhered so that the polarization axis was approximately 90 ° in accordance with the alignment treatment, and a TN positive liquid crystal display device was obtained.

Next, the cell thickness unevenness of the TN-positive liquid crystal display element was measured. The cell thickness was approximately constant at 3.8 to 4.2 μm (Δnd = 0.
However, in order to prevent the spacers from being whitened out during the black display by the enlarged projection of the liquid crystal display element, the spacers were not scattered, so that the cell thickness was 3 to 0.42). 0.0 to 5.5 μm (Δnd = 0.30
~ 0.55).

Here, in the present embodiment, the spacer was not scattered in the central part (display area), so that the cell thickness unevenness occurred more remarkably. However, even in the liquid crystal display device in which the spacer was scattered, the spacer displayed black. A similar cell thickness unevenness occurs because the amount of spacers to be sprayed cannot be increased in order to minimize the occurrence of white spots, and variations in spacer density due to spraying itself.

FIG. 2 is a schematic view showing the cell thickness unevenness of the TN positive type liquid crystal display device.

As shown in FIG. 2, a TN-positive liquid crystal display element in which the cell thickness in the central portion is smaller than the cell thickness in the peripheral portion, and a TN-positive liquid crystal display in which the cell thickness in the central portion is larger than the cell thickness in the peripheral portion. Classify the elements. At this time, it is desirable to make the levels of the cell thickness unevenness in the central portion as uniform as possible. For example, the difference of Δnd between the central portion and the peripheral portion is combined in 0.02 steps (when Δnd in the peripheral portion is 0.40, Δnd at the center is 0.4
The group of 0 to 0.42 is the UA group, and the center Δn
The group in which d is 0.42-0.44 is the UB group,
..., A group having a center Δnd of 0.40 to 0.38 is an LA group, and a center Δnd of 0.38 to 0.3
Group 6 is classified as LB group,...).

FIG. 3 is an optical system diagram of a projection type liquid crystal display device according to the present invention. The light from the metal halide lamp 7 is reflected by the dichroic mirror 8 into R, G, B
The light is separated into color lights, and the TN-positive liquid crystal display elements 11, 12, and 13 having uniform cell thickness unevenness levels as described above are optically switched, and the three color lights are synthesized again by the synthesis prism 9.
Enlarged projection is performed by the projection lens 10.

When the cell thickness of the TN positive type liquid crystal display element is not uniform, only the TN positive type liquid crystal display element of G color is colored magenta when the cell thickness at the center is small, and the T color of R color is obtained.
Whereas only the N-positive liquid crystal display element having a low cell thickness at the center was colored cyan, only the TN positive liquid crystal display element of B color was yellow when the cell thickness was low at the center. In the case where the cell thickness of the TN positive type liquid crystal display element was made uniform as in this example, an excellent projected image without coloring even in a halftone was obtained. Also, as compared with the case where the cell thickness of the TN positive type liquid crystal display element is not uniform, the usable range of the cell thickness unevenness is widened, so that the yield of the TN positive type liquid crystal display element is increased, and the projection type liquid crystal display device can be provided at low cost. became.

[Embodiment 2] A TN positive type liquid crystal display device was obtained in the same manner as in Embodiment 1, and then a TN type optical system shown in FIG.
The cell thickness of the positive-type liquid crystal display element was measured and combined.

FIGS. 4 and 5 are schematic diagrams showing cell thickness unevenness of each of the R, G, and B panels of the TN positive type liquid crystal display device.

The display area of the TN-positive liquid crystal display element is divided into four parts in each of the upper, lower, left, and right directions, for a total of 16 divisions, and the average cell thickness is calculated for each divided area.

For example, in the case of the projection type display device comprising the optical system shown in FIG. 3, the projected images of the R color TN positive liquid crystal display element 11 and the B color TN positive type liquid crystal display element 12 are G color TN.
Since the projected image of the positive liquid crystal display element 13 is inverted right and left, the TN positive liquid crystal display element 11 of R color and the TN positive liquid crystal display element 12 of B color are
Is compared with the line-symmetrical region of the G TN positive liquid crystal display element 13 (for example, 1a of the TN positive liquid crystal display element of R and B colors is compared with the TN positive liquid crystal display element 4a of G color). ), Are classified and combined so that the difference in average cell thickness is ± 0.2 μm or less.

Here, in the case of a vertical optical system, the projected image is inverted upside down, so that comparison is made in an area that is vertically symmetric with respect to the inversion plane 14 as shown in FIG.

In the present embodiment, the display area is divided into 16 regions for determination, but the number of divisions is not limited to 16, and the larger the number, the better. The processing can be simplified if the number of divisions is set to be an even number for the reflection surface.

As described above, by performing comparison and classification in a region that is line-symmetric with respect to the inversion surface, even a TN positive type liquid crystal display element having asymmetrical cell thickness unevenness, which has been regarded as defective, has no color unevenness. An excellent projected image was obtained, the yield of the TN-positive liquid crystal display device was greatly improved, and a projection display device could be realized at low cost.

Example 3 A TN-positive liquid crystal display device was obtained in the same manner as in Example 1, and the cell thickness of the TN-positive liquid crystal display device was measured in the same manner as in Example 2. The brightness unevenness of the system was measured, and the TN-positive liquid crystal display elements were classified and combined according to the wavelength characteristics of the optical system to be incorporated.

FIG. 6 shows the R and G of the optical system of the projection display device.
It is a luminance characteristic diagram for every B.

The luminance distribution of the optical system for each of R, G, and B is projected without the TN positive type liquid crystal display element attached, and the projected image is divided into 16 and measured.

The luminance of the central portion of the projected image is generally high due to the influence of the light source.
The result that the brightness at the lower right was lower than that of B was obtained.

Next, in order to eliminate color unevenness in the optical system of the projection type display device, TN positive type liquid crystal display elements were classified as follows.

First, in order to remove luminance unevenness in the central portion, the cell thickness of the TN positive type liquid crystal display device of R, G, B colors is selected such that the central portion has a smaller cell thickness than the peripheral portion.
Next, for the TN-positive liquid crystal display device for B color, the projected image is reversed left and right.
Also for the color TN-positive liquid crystal display device, the projected image is reversed left and right, so the lower left cell with a large cell thickness was selected. As described above, the TN-positive liquid crystal display device was selected and incorporated into a projection display device.

As described above, by classifying the TN positive type liquid crystal display elements used for each of the R, G, and B light in consideration of the luminance unevenness of the optical system of the projection display apparatus, an excellent color unevenness can be obtained. When the projection image is obtained and classified and incorporated, it is not necessary to rearrange the TN-positive liquid crystal display element, the production cost can be reduced, and the projection display device can be realized at low cost. did it.

[0036]

As described above, in the projection type liquid crystal display device of the present invention, the cell thickness unevenness of the plurality of liquid crystal display elements is such that the cell thickness at the central portion is higher than the cell thickness at the peripheral portion. With the configuration, the level of the cell thickness unevenness at the center of the plurality of liquid crystal display elements is made uniform, so that the usable range of the cell thickness unevenness can be widened as compared with the case where the cell thickness is not made uniform. As a result, the yield can be increased. Further, the color unevenness of the projected image can be suppressed as compared with the case where no combination is performed, so that an inexpensive and high-quality projection display device can be realized.

[0037]

[0038]

[0039]

[0040]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a TN positive type liquid crystal display device.

FIG. 2 is a schematic diagram of cell thickness unevenness of a TN positive type liquid crystal display element of Example 1 of the present invention.

FIG. 3 is an optical system diagram of the projection type liquid crystal display device of the present invention.

FIG. 4 is a schematic diagram of cell thickness unevenness for each of R, G, and B panels of a TN positive-type liquid crystal display element of Example 2 of the present invention.

FIG. 5 is a schematic diagram of cell thickness unevenness for each of R, G, and B panels of a TN positive-type liquid crystal display element of Example 2 of the present invention.

FIG. 6 is a diagram illustrating luminance characteristics of the optical system of the projection display device according to the third embodiment of the present invention for each of R, G, and B.

[Explanation of symbols]

 1. Transparent substrate 2. Transparent substrate 3. Spacer 4. Sealant 5. Liquid crystal 6. Polarizing plate 7. 7. Metal halide lamp Dichroic mirror 9. Synthetic prism 10. Projection lens 11. R color TN positive type liquid crystal display element 12. TN positive type liquid crystal display device of B color 13. TN positive type liquid crystal display device of G color Reflective surface

Claims (1)

(57) [Claims] 1. A projection type liquid crystal in which light from a light source is separated by an optical system, light is switched using a plurality of liquid crystal display elements, and light is synthesized again by the optical system to obtain an enlarged projected image by an enlarged projection system. In the display device, the cell thickness unevenness of the plurality of liquid crystal display elements is configured such that a cell thickness in a central portion is higher than a cell thickness in a peripheral portion , and the plurality of liquid crystal display
The level of cell thickness unevenness at the center of the element is uniform.
Projection type liquid crystal display device, characterized in that there.