JPH01114824A - Projection type liquid crystal display panel - Google Patents

Abstract

PURPOSE:To improve the display quality by constituting the title panel so that a dot shape and its arrangement interval of a liquid crystal panel of a second layer and above are reduced successively against a dot shape and its arrangement interval of a liquid crystal panel of a first layer. CONSTITUTION:A dot shape which is delimited by the width of opposed electrodes of a projection type liquid crystal display panel 32 and a second liquid crystal panel 33 of the second layer, and a dot arrangement interval which is determined by an electrode provided pitch consist of a constitution in which a dot shape of a first liquid crystal panel 32 and its arrangement interval are reduced to match a distance between its liquid crystal panel and a projection lens 36 of a projection optical system to be combined. In such a way, dots (picture elements) 32f, 33f corresponding to each of the liquid crystal panels 32, 33 of the first layer and the second layer come to be superposed surely in a projection display, and a projection type color liquid crystal display panel 31 of a double layer panel structure being free from a picture element shift can be obtained.

Description

[Detailed Description of the Invention] [Summary] A projection type color liquid crystal display panel for a large screen display using a phase change liquid crystal as a light valve, particularly a panel structure that prevents deterioration of color display quality due to pixel misalignment. The purpose of this system is to ensure that the corresponding display pixels (dots) in each of the liquid crystal panels that make up the laminated color LCD panel overlap in projection display, thereby preventing pixel misalignment. In a liquid crystal display panel in which at least two different liquid crystal panels are stacked, and the transmittance of the liquid crystal layer of each of the stacked liquid crystal panels is controlled to project a multicolor dot display using light irradiated from the back of the first layer panel, the above-mentioned method is provided. The configuration is such that the dot shape and arrangement interval of each of the second and subsequent layer liquid crystal panels are sequentially reduced with respect to the dot shape and arrangement interval of the first layer liquid crystal panel.

[Industrial application field]

The present invention relates to a projection type color liquid crystal display panel for a large screen display using a phase change type liquid crystal as a light valve, and more particularly to a panel structure that prevents deterioration of color display quality due to pixel misalignment.

Projection display systems that use high-brightness CRTs, lasers, or light valves instead of blackboards or overhead projectors (OHP) have already been put into practical use as large-screen displays, but all of these methods rely on highly accurate optics. Since it uses a system, it is expensive and has a problem of lack of widespread use.

Under these circumstances, recently, a projection type liquid crystal display panel for large screen display using a phase change type liquid crystal (mixed liquid crystal of nematic liquid crystal and cholesteric liquid crystal) as a light valve has been proposed.

Originally, this projection type liquid crystal display panel was mainly used for black and white display, but later on, color display was promoted due to the increased use of information, and a panel structure that enabled color display without pixel misalignment was required. ing.

[Prior Art] As shown in FIGS. 7(a) to (C), a projection type black-and-white display panel using a phase change liquid crystal is provided with transparent electrodes (not shown) each covered with an alignment film on the inner surface. A pair of transparent substrates 1a and lb are arranged facing each other with a predetermined interval,
It has a configuration in which a phase change type liquid crystal 2 is filled between the substrates 1a and 1b, and information is displayed based on the nematic/cholesteric phase transition phenomenon of the phase change type liquid crystal 2 (using the hysteresis phenomenon of light transmittance). This is what we do.

The operating principle is the pair of transparent groups vila.

When a high voltage is applied to the electrode 1b, the liquid crystal molecules in the phase change liquid crystal layer 2 are aligned perpendicularly to the opposing substrates 1a and 1b along the electric field, as shown in FIG. It becomes a transparent state of nematic phase, and the incident light passes through the projection lens 3.
The light is focused by the screen, and becomes bright on the opposing screen (not shown). 2a shows vertically aligned liquid crystal molecules.

When the applied voltage is lowered, as shown in FIG. 7(C), the liquid crystal molecules are oriented in a spiral due to their own force, undergo a phase transition to a cholesteric phase, and enter a light scattering state.
The incident light is scattered and is not focused by the projection lens 3, resulting in a dark state on the opposing screen (not shown). 2b is a liquid crystal molecule oriented in a spiral manner.

Therefore, such a phase change type liquid crystal display panel 11 is mounted on the 01 (PI3) as shown in FIG. After writing display information using the two phase transition states, the projection unit 15 converts the nematic phase H' by applying the bistable maintaining voltage Vd.
The information is enlarged and projected on the screen 16 in two black and white states, ie, cholesteric phase F and cholesteric phase F.

On the other hand, a method has also been proposed in which color display is performed by making the light transmitted through the liquid crystal wavelength dependent by controlling the helical pitch and the like of the liquid crystal by controlling the material composition.

A color liquid crystal display panel using this method includes, for example, a first liquid crystal panel that has a display color that undergoes a phase transition from a white transparent state to a red scattering state, and a second liquid crystal panel that has a display color that undergoes a phase transition from a white transparent state to a green scattering state. It has a structure that enables multi-color display by overlapping two liquid crystal panels, and by attaching this to the OHP12 as explained in FIG. 8, it is possible to display enlarged color information.

[Problem that the invention seeks to solve]

By the way, as shown in FIG. 9(a), the first liquid crystal panel 22 has a display color that undergoes a phase transition from the white transparent state to the red scattering state, and the first liquid crystal panel 22 has a display color that exhibits a phase transition from the white transparent state to the green scattering state. When the display pixels of the color liquid crystal display panel 21 having a two-layer structure in which the second liquid crystal panel 23 is laminated have a dot matrix configuration, the transmittance of the liquid crystal layer of these panels is controlled, and the irradiation light from the light emitting source 13 is controlled. The light emitted from the display panel 21 is directed to the opposing screen 16 via the projection lens 15a by making the light enter from the back of the panel through the condensing lens 14 made of a Fresnel lens.
When projecting on top and displaying dots, each LCD panel 2
The projection magnification at the periphery of the panel differs due to the thickness of the substrates 2 and 23 and the distance between the projection lens 15a and each liquid crystal panel 22, 23. The dot pattern B of the second liquid crystal panel 23 corresponding to the dot pattern A of the liquid crystal panel 22 is displayed superimposed with a pattern shift as shown by the broken line. - That is, to further explain such a phenomenon with reference to FIG. The screen 1 faces the picture elements b (dots) of the second liquid crystal panel 23 through the projection lens 15a.
6, the difference between the distance between the picture element a and the projection lens 15a and the distance between the picture element a and the projection lens 15a (
ao > bo), the relationship between the projection pattern A of the picture element a on the screen 16 and the projection pattern B of the picture element is X+'Y+°<X,'Y,'' and these picture element patterns There is a problem in that so-called pixel misalignment occurs and display quality deteriorates.

In view of the above-mentioned conventional problems, the present invention has been developed by configuring mutually corresponding display pixels (dots) in each liquid crystal panel that constitutes a laminated projection type color liquid crystal display panel so that they overlap with each other in projection display. The object of the present invention is to provide a new projection type color liquid crystal display panel that prevents misalignment.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention stacks at least two liquid crystal panels 32 and 33 with different display colors as shown in the principle diagram of FIG. 1(a), While controlling the transmittance of each of these liquid crystal layers, a multicolor dot display is projected through the projection lens 36 using light emitted from the light emitting source 34 on the back side of the -i-th panel through the condensing lens 35. In the liquid crystal display panel 31, the first layer liquid crystal panel 3
The dot shape 33f and the arrangement interval of the second-layer liquid crystal panel 33 are reduced in accordance with the distance between the liquid crystal panel 33 and the projection lens 36 compared to the dot shape 32f and the arrangement interval of the second-layer liquid crystal panel 33.

[Function] In the projection type color liquid crystal display panel of the present invention having a two-layer panel structure, the dot shape 33f of the second layer liquid crystal panel 33 is different from the dot shape 32f of the first layer liquid crystal panel 32 and its arrangement interval. and the arrangement interval thereof, the liquid crystal panel 33
Since the structure is scaled down according to the distance between the screen and the projection lens 36, the mutually corresponding dots (picture elements) 32F and 33F on the first and second layer liquid crystal panels 32 and 33 are reliably overlapped in the projected display. 'It becomes like that. That is, as shown in FIG. 1(b), the relationship between the dot shapes x, y of the first liquid crystal panel 32 and the dot shapes X, Y of the second liquid crystal panel 33, which are arranged at a predetermined interval d, is expressed as X+Y+>X.
zYz, the dot shapes X, Y, and the projection lens 36
If the relationship between the distance between the dot shape X2Y and the distance between the projection lens 36 is X, Y, ・O>XzYz・0,
dot shapes x and y of the first liquid crystal panel 32;

By superimposing and projecting the dot shape XtYz of the second liquid crystal panel 33 onto the opposing screen 37 via the projection lens 36, the dot shape X on the screen 37 is
, Y, and the projection pattern B of dot shape XzYz are as follows: X+'Y+' = Xz'Yz'
This prevents picture element misalignment.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a sectional view of a main part of an embodiment of a projection type color liquid crystal display panel according to the present invention.

In the figure, reference numeral 32 indicates a display that undergoes a phase transition from a white transparent state to a red scattering state, for example, between a pair of transparent glass substrates 32a and 32b, each of which has a striped transparent electrode 32c covered with an alignment film 32d on its inner surface. This is a first liquid crystal panel filled with colored phase change type liquid crystal 32e, and on the first liquid crystal panel 32, a pair of transparent electrodes 33c in the form of stripes whose inner surfaces are covered with an alignment film 33d are provided. The second liquid crystal panel 33 is laminated between glass substrates 33a and 33b, and is filled with a phase change type liquid crystal 33e whose display color changes from a white transparent state to a red scattering state, for example. ing.

Further, the shape of the dots defined by the width of the opposing electrodes of the first liquid crystal panel 32 of the first layer and the second liquid crystal panel 33 of the second layer and the dot arrangement interval determined by the electrode arrangement pitch are 32, the dot shape and the arrangement interval of the second liquid crystal panel 33 are reduced in accordance with the distance from the projection lens 36 of the projection optical system (not shown) combined with the liquid crystal panel 33. The structure is as follows.

That is, to explain in more detail the relationship between the dot shapes of the first and second liquid crystal panels 32 and 33, for example, as shown in FIG.
2f length! 1. The length of the dot shape 33'' of the second liquid crystal panel 33 of the second layer is 1-2, and the first liquid crystal panel 32
Assuming that the distance between and the projection lens 36 is d, the distance between the first liquid crystal panel 32 and the second liquid crystal panel 33 is Δd, and the solid angle when viewing the surface of the first liquid crystal panel 32 from the projection lens 36 is θ,
The length of the dots on the second liquid crystal panel 33! , is the length of the dot on the first liquid crystal panel 32 21-2·Δd tan (θ
/2).

Note that the dots (picture elements) on the first and second liquid crystal panels 32 and 33
The ratio of is determined by the following formula.

1, / l g=2dtan(θ/2)/(d・Δ
d) jan (θ/2) Figure 4 shows the first and second liquid crystal panels 3
2.33 is a conceptual diagram three-dimensionally showing the dot shape and arrangement configuration.

In this way, the mutually corresponding dots (picture elements) 32f and 33f of the first and second layer liquid crystal panels 32 and 33 will surely overlap in the projection display, and a two-layer panel structure with no pixel misalignment will be realized. A projection type color liquid crystal display panel 31 can be obtained.

Therefore, the projection type color liquid crystal display panel 31 of the present invention is mounted on the 0HP 41 as shown in FIG.
Light is emitted from the light emitting source 42 of the HP 41 to the back of the panel through a condensing lens 43 made of a Fresnel lens, etc., and display data stored in advance is displayed as necessary by a personal computer 44 or a disk driver 45. The data is edited and read out to the control unit 46. This display data signal is converted into a drive voltage necessary for display drive in the panel drive circuit 47 via the control unit 46,
By supplying the liquid crystal display panel 31 to the liquid crystal display panel 31, a desired color liquid crystal display image formed on the surface of the liquid crystal display panel 31 is displayed on a screen 49 via a projection unit 48 composed of a projection lens, a reflecting mirror, etc. It becomes possible to display clearly enlarged images without any deviation.

In the above embodiments, an example was explained in which the projection type color liquid crystal display panel had a structure in which two liquid crystal panels with different display colors were stacked, but the present invention is not limited to this example. For example, it is of course applicable to a structure in which three liquid crystal panels or three or more liquid crystal panels with different color displays are stacked, and similar effects can be obtained.

Furthermore, as shown in FIG. 6, a two-layer liquid crystal panel with different display colors includes a back side transparent substrate 51 and a front side transparent substrate 52, each of which has a transparent electrode 54 covered with an alignment film 55 on its inner surface. A liquid crystal layer 56.5 with different display colors between
Transparent electrode 5 coated with an alignment film 55 on both sides with 7 interposed therebetween.
4 may be used.

〔Effect of the invention〕

As is clear from the above description, according to the projection type color liquid crystal display panel according to the present invention, when color liquid crystal display information is projected and enlarged on the screen in combination with an OHP, it can be clearly displayed without pixel shift. A color display image can be realized,
Display quality can be improved.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are principle diagrams illustrating the elimination of pixel misalignment in a projection type color liquid crystal display panel according to the present invention, and FIG. 2 is an embodiment of a projection type color liquid crystal display panel according to the present invention. 3 is a diagram for explaining the relationship between the dot shapes of the first liquid crystal panel and the second liquid crystal panel in the projection type color liquid crystal display panel according to the present invention, and FIG. 4 is a cross-sectional view of the main parts according to the present invention. A conceptual diagram showing three-dimensionally the dot shape and arrangement configuration of the first liquid crystal panel and the second liquid crystal panel in such a projection type color liquid crystal display panel, and FIG. 5 is a projection optical system using the projection type color liquid crystal display panel according to the present invention. An explanatory diagram showing an example of the system, FIG. 6 is a sectional view of main parts showing another embodiment of the projection type color liquid crystal display panel according to the present invention, and FIGS. 7(a) to (C) are phase change type liquid crystal panels. Figure 8 is an explanatory diagram showing an example of a projection optical system using a conventional projection type liquid crystal display panel. Figures 9 (a) and (b) are conventional projection type color liquid crystal display panels. FIG. 2 is a diagram for explaining the problem. 1 to 6, 31 is a color liquid crystal display panel, 32 is a first liquid crystal panel,
32a, 32b, 33a, 33b are transparent glass substrates, 32c, 33c, 54 are transparent electrodes, 32
d, 33d. 55 is an alignment film, 32e, 33e, 56, 57
is LCD, 32F. 33f, X, Y, , X, Y are dot shapes, 33 is a second liquid crystal panel, 34.42 is a light emitting source, 35.43 is a condenser lens, 36 is a projection lens, 41 is an OHP, 44 is a personal computer, 45 is a disk driver, 46 is a control circuit, 47 is a drive circuit, 48 is a projection section, 49 is a screen, 51 is a rear side transparent substrate, 52 is a front side transparent substrate, and 53 is an intermediate transparent substrate. Figure 1 (Q) Shito360月^St″fjthft4iN1shikuzucho p!
Otsuro Fig. 1 (b) Fig. 2 Fig. 3 Fig. 5 Fig. 6 a -erJ7JOtFE (V)

Claims (1)

[Claims] At least two liquid crystal panels (32, 3
3) are stacked, and each of the stacked liquid crystal panels (32,
In the liquid crystal display panel (31) that controls the transmittance of the liquid crystal layer and projects a multicolor dot display using light irradiated from the back of the first layer panel, the dot shape (32f) of the first layer liquid crystal panel (32) is
) and the second or higher layer liquid crystal panel (
33) A projection type liquid crystal display panel characterized in that the dot shape (33f) and the arrangement interval thereof are configured to be gradually reduced.