JP3038575B2 - Projection display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection display device using a liquid crystal light valve.

[0002]

2. Description of the Related Art A projection type display device using a conventional liquid crystal light valve is disclosed in JP-A-60-179723 and JP-A-6-179723.
As described in JP-A-1-35481, an image is formed by controlling red light, green light, and blue light by a liquid crystal light valve in which pixels are arranged in a matrix, and then the three color lights are optically synthesized. What enlarges and projects is known.
The above-described color synthesis is generally performed by an optical system combining a dichroic mirror. The color synthesis by the dichroic mirror system has a very simple optical system and is suitable for obtaining a compact projection display device.

[0003]

However, in the above-mentioned prior art, in the light synthesis of the dichroic mirror system, the light enters the projection lens system through an even number of reflections and enters the projection lens through the projected color light and the odd number of reflections. The presence of the projected colored light induces the deterioration of the image quality of the projected image described below.

A conventional problem is synthesized because a repetitive pattern image of a switching element or a light shield layer constituting a liquid crystal light valve is guided to a projection lens while inverting the image left and right through reflections of even and odd times. In the projected image, the light shield layer or the switching element is reflected so as to overlap two patterns. For this reason, the screen becomes rough, and at the same time, color unevenness occurs in the repeating unit of the pixel, and the color reproducibility is significantly reduced.

The present invention has been made to solve the above-mentioned problems, and provides a projection type display device which is excellent in color reproducibility without color unevenness in a projected image even when the above-described dichroic mirror-based color synthesis is used.

[0006]

SUMMARY OF THE INVENTION The present invention provides a plurality of liquid crystal light valves for respectively modulating a plurality of color lights, a color synthesizing means for synthesizing a plurality of color lights modulated by the liquid crystal light valves, and the color synthesizing means. And a projection optical means for projecting the light combined in the projection optical device, wherein the plurality of liquid crystal light valves are subjected to an even number of reflections after modulation or without reflection after modulation. A first type of liquid crystal light valve for modulating the color light guided to the means, and a second type of liquid crystal light valve for modulating the color light guided to the projection optical means through an odd number of reflections after being modulated, The first type of liquid crystal light valve and the second type of liquid crystal light valve include a pixel electrode arranged in a matrix, a switching element connected to the pixel electrode, and a switch. A liquid crystal panel having an arrangement light shielding layer so as to cover the switching element, the first
The liquid crystal panel of the liquid crystal light valve of the type and the liquid crystal panel of the liquid crystal light valve of the second type are configured such that the arrangement positions of the switching elements arranged respectively are plane-symmetric with each other. .

[0007]

According to the structure of the projection type display device of the present invention, in color synthesis, the color light which enters the projection lens system through an even number of reflections (or 0 times) and the color light which enters the projection lens system through an odd number of reflections. The optical configuration of the liquid crystal light valve that controls the color light can be in a plane-symmetric relationship. In other words, the arrangement of the switching elements of the liquid crystal light valve for controlling the color light guided to the projection lens system through the odd number of reflections and the even number (or zero) times of reflection in the color synthesizing optical system can be symmetrical with each other.

An image of color light passing through an even number of reflections (or 0 times) is projected left and right inverted while an image of a color light passing through an odd number of reflections is projected while maintaining the left-right positional relationship. In the projection type display device, since the arrangement of the switching elements is provided in advance so as to be plane-symmetrical between the liquid crystal light valves controlling the color light reflected oddly and the color light reflected evenly, the projection is enlarged after the color synthesis. The pattern of the switching elements can be completely matched on the screen. That is, it is possible to obtain a projection image having excellent color reproducibility without color unevenness in each repeating unit in the projection image.

[0009]

FIG. 1 is a perspective view of a liquid crystal light valve of a projection type display device according to a reference example, FIGS. 2 and 3 are diagrams showing an orientation distribution of the liquid crystal light valve, and FIG. FIGS. 5 and 6 are left and right distribution diagrams of light intensity. The present embodiment will be described below with reference to FIGS.

An active matrix liquid crystal panel was used as a liquid crystal light valve. Thin film transistors (TFTs) 102 arranged in a matrix as switching elements
Was formed on a transparent substrate. On the other hand, a light shield layer 101 is provided on the opposing substrate so as to shield the area other than the effective pixel area from light, an alignment inducing layer is formed on the pair of substrates, and rubbing is performed. Then, the pair of substrates is combined to obtain a liquid crystal light valve. Was. As the TFT, a polysilicon TFT, an amorphous silicon TFT, a compound semiconductor TFT, or the like is used. Further, the object of the present embodiment can be attained by driving by a switching method such as an MIM element having a diode characteristic, a ring diode element, a back-to-back diode element, or a simple multiplexing method.

Two types of liquid crystal light valves having a liquid crystal orientation distribution which is characteristic of this embodiment and which are plane-symmetric to each other were obtained as follows. That is, by controlling the rubbing directions of the alignment treatment of the upper and lower substrates of the light valve, a plane-symmetric liquid crystal alignment distribution was obtained. A panel rubbed on the TFT substrate in the rubbing direction 201 and a rubbing direction 202 on the counter substrate side and a panel rubbed on the TFT substrate side in the rubbing direction 301 and in the rubbing direction 302 were obtained. In both panels, the intersection angle between the orientation axes of the upper and lower substrates is 80 °. When the nematic liquid crystal was sealed in the above panel, one of the panels obtained a twisted nematic (TN) liquid crystal light valve having a right twist and a TN liquid crystal light valve having a left twist. As described above, in order to more stably maintain the alignment distribution of the liquid crystal having a symmetric twist direction, or to obtain a liquid crystal panel having a twist angle of 90 ° or more, an optically active agent may be mixed into the nematic liquid crystal. For example, the object of this embodiment can be achieved by mixing a dextrorotatory optically active agent into a right-twisted TN liquid crystal and a levorotatory optically active agent into a left-twisted TN liquid crystal.

Using the liquid crystal light valve obtained as described above, a projection display device was obtained with the optical configuration shown in FIG. The light from the light source 401 is separated into red, green, and blue lights by a blue reflecting dichroic mirror 402 and a green reflecting dichroic mirror 403, and the liquid crystal light valve for red light 406 and the liquid crystal light valve for green light 40, respectively.
5. Light is incident on the liquid crystal light valve 404 for blue light. After image formation, the color is synthesized by the dichroic mirror prism 407 and projected by the projection lens 410. The dichroic mirror prism 407 is formed by bonding four right angle prisms, and has a red light reflecting dichroic mirror surface 408 and a blue light reflecting dichroic mirror surface 409.
In the color composition by the dichroic mirror prism 407, red and blue colors are combined by one reflection, and green light is combined by transmission (0 reflections) and guided to the projection lens.
In this projection display device, the liquid crystal light valves for red and blue light have an alignment distribution of right-twisted liquid crystal as shown in FIG. 2, and the liquid crystal light valve for green light has a left-handed liquid crystal as shown in FIG. It has an orientation distribution of twisted liquid crystals, and has a plane-symmetric relationship with each other. Even if the combination of the liquid crystal light valve and the orientation distribution of the liquid crystal is reversed, the object of this embodiment is achieved. The light intensity distribution of the projection display device having the above configuration was examined. As shown in FIG. 5, the left-right distribution of light intensity after image formation is such that red light, blue light and green light are symmetric with respect to the center of the screen. In the process of color synthesis using the dichroic mirror prism 407, the red light and the blue light have undergone one reflection, so that the light intensity distribution is reversed left and right, so that the left and right light intensity distributions of the projected image are as shown in FIG. There is no difference between light. Therefore, since a specific color light is not strongly reflected, color unevenness does not occur. Also, the color reproducibility is excellent. The light intensity distribution due to the effect of diffused light is controlled between the color lights by setting the alignment distribution of the liquid crystal of the liquid crystal light valve that controls the color light passing through the even and odd times of reflection in the color synthesis so as to be plane symmetric. By doing so, the color unevenness of the projected image was eliminated, and a projection display device with excellent color reproducibility was obtained.

Reference Example 2 Using the liquid crystal light valve obtained in the same manner as in Reference Example 1, a projection display device was obtained with the optical configuration shown in FIG.

Light from a light source is reflected by a yellow light reflecting dichroic mirror 701 and a green light reflecting dichroic mirror 40.
The light is divided into red, green, and blue lights by 3 and enters the liquid crystal light valve 406 for red light, the liquid crystal light valve 405 for green light, and the liquid crystal light valve 404 for blue light. In the color synthesis in the optical configuration of the projection display device of the present reference example, the red light is reflected once by the red light reflecting dichroic mirror surface 409,
Green light is transmitted (reflected 0 times), and blue light is mirror 706.
The light is reflected twice by the blue light reflecting dichroic mirror surface 408 and guided to the projection lens 410.

A right-twisted TN liquid crystal is used for the liquid crystal light valve 404 for blue light and the liquid crystal light valve 405 for green light, and a liquid crystal light valve 406 for red light is left-twisted as shown in FIG. A TN liquid crystal was used to have a liquid crystal alignment distribution that was plane-symmetric with each other. Also in this reference example, an image excellent in color reproducibility without color unevenness in the projected image was obtained.

FIG. 8 is a cross-sectional view of a liquid crystal light valve using the projection display device of the present embodiment. FIGS. 9 and 10 are diagrams showing a repetitive pattern of a light shield layer of the liquid crystal light valve. It is.
4 and 11 are optical configuration diagrams of the projection type display device of the present embodiment. This embodiment will be described below with reference to FIGS. 4 and 8 to 11.

Polysilicon thin film transistor (TFT) as means for controlling the liquid crystal electro-optic effect on a transparent substrate
Alternatively, active switching elements 801 such as amorphous silicon TFTs and pixel electrodes 802 were formed in a matrix. Further, on the other substrate, a light shielding layer 803 was formed in a lattice shape using a dyed layer or a metal thin film so as to cover a region other than the pixel electrode 802.
After the desired alignment treatment, the two substrates were bonded together, and the liquid crystal composition 804 was sealed to obtain a liquid crystal light valve. The shape of the light shield layer of the liquid crystal light valve is such that the repeating unit has a repeating pattern 901 and a repeating pattern 100.
One piece and two pieces of two kinds each of which are plane-symmetric were prepared. In this embodiment, the repetition pattern 901 and the repetition pattern 1001 have a plane-symmetric relationship with each other, and the arrangement of the active switching elements is also formed with a plane-symmetric arrangement as covered by the light shield layer.

A liquid crystal light valve 405 for green light in which the light shield layer has a repeating pattern 901 and a liquid crystal light valve 406 for blue light and a liquid crystal light valve 404 for blue light in which the light shield layer has a repeating pattern 1001 are used. Light was allowed to enter from the 103 side to obtain a projection type display device having the configuration shown in FIGS.

In the configuration shown in FIG. 4, red light is guided to the projection lens 410 through a red light reflecting dichroic mirror surface 408, and blue light is reflected once by a blue light reflecting dichroic mirror surface 409. On the other hand, the G light enters the projection lens 410 without being reflected at all (by zero reflection).

Therefore, the images of red and blue light are horizontally inverted, and the image of green light is projected as it is. In this embodiment, since the patterns of the light shield layers of the liquid crystal light valves for red light, blue light and green light are plane-symmetric with each other, they completely match in the image projected after the above mirror inversion. Therefore, color unevenness does not occur in the pixel.

On the other hand, in the configuration shown in FIG. 11, after the red light is image-formed by the liquid crystal light valve 406 for red light, it is guided to the projection lens 410 via the mirror 706 and the red light reflecting dichroic mirror surface 409 twice reflected. .
Green light is image-formed by a green light liquid crystal light valve 405 and a green light reflecting dichroic mirror surface 1101 is formed.
Is guided to the projection lens 410 through one reflection.
The blue light is guided by the blue light liquid crystal light valve 404 to the projection lens without being reflected after image formation. Accordingly, the red and blue lights are projected without changing the left and right positions, and the green light is projected with the left and right positions interchanged. In this embodiment, since the patterns of the light shield layers of the light valves for red and blue light and the light valve for green light are plane-symmetric with each other, the patterns of the light shield layers completely match in the image projected after the above mirror inversion. I do. As described above, it has been found that the projection image of the projection display device of the present embodiment is a projection image having faithful color reproducibility without causing color unevenness in a pixel unit. The optical configuration of the projection display device of the present invention is not limited to those shown in FIGS. The object of the present invention can be easily achieved if the repetitive patterns of the light shield layers of the liquid crystal light valve for controlling the color light which is subjected to odd and even reflections during the color synthesis are plane-symmetric with each other.

Further, also in this embodiment, the liquid crystal light valve which undergoes an even number of reflections and the liquid crystal light valve which undergoes an odd number of reflections at the time of color synthesis are made plane-symmetrical, so that the above-mentioned color unevenness in the pixel is achieved. In addition, the color unevenness of the entire screen can be suppressed. For example, in this embodiment, when the TN mode is used, the liquid crystal light valve 405 for green light is used.
The liquid crystal light valve 406 for red light and the liquid crystal light valve 404 for blue light hold TN liquid crystals of left twist as shown in FIG. For example, similarly to Reference Examples 1 and 2, a projection image having excellent color reproducibility without color unevenness over the entire screen can be obtained.

(Embodiment 3) FIG. 8 is a sectional view of a liquid crystal light valve of a projection type display device according to this embodiment, and FIG. 12 is a repeated pattern diagram of a light shield layer of the liquid crystal light valve. 4 and 11 are optical configuration diagrams of the projection display device of the present embodiment.

A liquid crystal light valve was obtained with the same structure as shown in FIG. The liquid crystal light valve of this reference example has a repeating pattern 1201 of the light shield layer of FIG. 12, and the repeating pattern has an axially symmetric shape with respect to a central axis 1202 in the vertical direction. Using three liquid crystal light valves having a light shield layer having the above-described pattern, a projection display device was obtained in the same configuration as in FIGS. In this reference example, the liquid crystal alignment distributions of the liquid crystal light valve for green light 405, the liquid crystal light valve for red light 406, and the liquid crystal light valve for blue light 404 are plane-symmetrical with each other. The liquid crystal was held.

The pattern of the repeating unit of the light shield layer of the liquid crystal light valve for red light, green light, and blue light of the projection type display device of this embodiment is plane-symmetric with each other and axially symmetric with respect to the center axis in the vertical direction. Therefore, even if the left and right positions are inverted, they completely match the shape before the inversion. Therefore, even if mirror reversal is performed many times during color synthesis, the repetition pattern does not change, so that the color light pixel patterns formed by the three liquid crystal light valves in the projected image completely match, and color unevenness does not occur. . This means that the same pattern can be used for the repetition patterns of the light shield layers of the three liquid crystal light valves, and the same process can be used for all the processes for forming the light shield layers. Normally, a photolithography technique is used to form a light shielding layer, but only one photomask or the like is required at that time, so that the manufacturing process can be simplified and a liquid crystal light valve can be obtained at lower cost. The repetitive pattern of the light shield layer is not limited to the present embodiment, but may be any pattern as long as it is axially symmetric with respect to the central axis in the vertical direction. For example, a pattern as shown in FIG. Further, the object of the present embodiment can be easily achieved even if the pixel arrangement is a triangle arrangement or the like.

Further, in this embodiment, the orientation distribution of the liquid crystal of the liquid crystal light valve which undergoes even-number reflection and odd-number reflection during the color synthesis is plane-symmetric with respect to each other, and thus depends on the incident angle dependence of the photoelectric conversion characteristic of the liquid crystal light valve. It was found that color unevenness did not occur and the color reproducibility was excellent.

[0027]

As described above, according to the projection type display apparatus of the present invention, the color light guided to the projection optical means is modulated through even-numbered reflection after modulation or without reflection after modulation. A liquid crystal light valve of a first type, and a liquid crystal light valve of a second type for modulating color light guided to the projection optical means through an odd number of reflections after being modulated. A liquid crystal light valve of the type includes a liquid crystal panel having a pixel electrode arranged in a matrix, a switching element connected to the pixel electrode, and a light shield layer arranged to cover the switching element. The liquid crystal panel of the liquid crystal light valve of the type 2 and the liquid crystal panel of the liquid crystal light valve of the second type
Since the arrangement positions of the switching elements respectively arranged are plane-symmetric with respect to each other, the projection of the switching elements of each liquid crystal panel and the light shield layer covering the switching elements in the enlarged projection screen after color synthesis. The obtained pattern can be matched between the color lights. Thereby,
A projection image excellent in color reproducibility in which color unevenness is suppressed within a unit of each projection pattern in the projection image can be obtained.

In this way, an excellent image can be obtained even if a dichroic mirror prism is used in which the odd and even reflections always occur in each color during color synthesis.

[Brief description of the drawings]

FIG. 1 is a perspective view of a liquid crystal light valve.

FIG. 2 is a liquid crystal alignment distribution diagram.

FIG. 3 is a liquid crystal alignment distribution diagram.

FIG. 4 is an optical configuration diagram of a projection display device.

FIG. 5 is a left-right distribution diagram of light intensity after image formation.

FIG. 6 is a left-right distribution diagram of light intensity of a projection image.

FIG. 7 is an optical configuration diagram of a projection display device.

FIG. 8 is a sectional view of a liquid crystal light valve.

FIG. 9 is a repeated pattern diagram of a light shield layer of a liquid crystal light valve.

FIG. 10 is a repetitive pattern diagram of a light shield layer of a liquid crystal light valve.

FIG. 11 is an optical configuration diagram of a projection display device.

FIG. 12 is a repetitive pattern diagram of a light shield layer.

FIGS. 13A and 13B are repetitive pattern diagrams of a light shield layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 ... Thin film transistor 102 ... Light shield layer 201 ... Rubbing direction of TFT substrate 202 ... Rubbing direction of counter substrate 301 ... Rubbing direction of TFT substrate 302 ... Rubbing direction of counter substrate 401 ... Light source 402 ... Blue reflective dichroic mirror 403: Green reflective dichroic mirror 404: Liquid crystal light valve for blue light 405: Liquid crystal light valve for green light 406: Liquid crystal light valve for red light 407: Dichroic mirror prism 408: Red light reflection Dichroic mirror surface 409 Blue light reflecting dichroic mirror surface 410 Projection lens 701 Yellow light reflecting dichroic mirror 706 Mirror 801 Active switching element 802 Pixel electrode 803 Light shield layer 804 Liquid Composition 901, 1001 ...... repetitive pattern 1101 ...... green light reflection dichroic mirror surface 1201 ...... repetitive pattern 1202 ...... vertical center axis

Claims (1)

(57) [Claims] 1. A liquid crystal light valve for modulating a plurality of color lights, a color synthesizing means for synthesizing a plurality of color lights modulated by the liquid crystal light valve, and a light synthesized by the color synthesizing means. The projection type display device having projection optical means, wherein the plurality of liquid crystal light valves modulates color light guided to the projection optical means through an even number of reflections after modulation or without reflection after modulation. A first type of liquid crystal light valve; and a second type of liquid crystal light valve for modulating color light guided to the projection optical means through an odd number of reflections after being modulated. The second type of liquid crystal light valve includes: pixel electrodes arranged in a matrix; a switching element connected to the pixel electrodes;
A liquid crystal panel having a light shield layer disposed so as to cover the switching element, wherein the liquid crystal panel of the first type liquid crystal light valve and the liquid crystal panel of the second type liquid crystal light valve are respectively disposed. A projection type display device, wherein the arrangement positions of the switching elements are plane-symmetric with respect to each other.