JP2003066405A - Optical path deflecting element, image display device and method for controlling optical path deflecting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apparently increase the number of pixels of an image display element and to dissolve a color shift caused by deviation of transmitted and deflected light quantity produced by the difference in color of the pixels. SOLUTION: Light emitted from a white lamp 121, which is a light source, controlled by a light source driving means 111 turns into uniformized illumination light by a diffusion plate 122 and critically illuminates a transmissive liquid crystal light valve 124 which is a picture display element through a condenser light lens 123. The image of the illumination light spatially light-modulated by the transmissive liquid crystal light valve 124 is maginied by a projection lens 126 and projected on a screen 127. In this case, the image light is shifted by an arbitrary distance in a pixel aligning direction by control of a voltage applied to an optical path deflecting element 125 arranged in the rear of the transmissive liquid crystal light valve 124, using an optical path deflecting voltage controlling means 113.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path deflecting element, an image display device, and a method of controlling the optical path deflecting element, and more particularly to applying a control voltage to a transparent electrode to change the polarization ratio of liquid crystal molecules to deflect the optical path. The present invention relates to an optical path deflecting element, an image display device using the optical path deflecting element, and a method of controlling the optical path deflecting element.

[0002]

2. Description of the Related Art In a conventional image display device using an optical path deflecting element, for example, when a liquid crystal is used, when the number of pixels of the optical path deflecting element unit is increased, the aperture ratio is deteriorated or the brightness is reduced. There are point defects,
This will reduce the yield during production, which will
Increasing costs were unavoidable. Therefore, in actuality, the apparent number of pixels is increased without increasing the number of pixels of the optical path deflecting element unit, and at the same time,
Various technologies have been devised to improve the contrast on the display screen. A retrospective examination of a conventional method for controlling an optical path deflecting element and a technique relating to an image display device is made for a patent publication. For example, in Japanese Patent No. 2939826, an image displayed on the display element is projected on a screen by a projection optical system. In a projection display device for magnifying and projecting, at least one optical element capable of turning the polarization direction of transmitted light in the optical path from the display element to the screen and at least one transparent element having a birefringence effect are provided. And a means for effectively reducing the aperture ratio of the display element so that the projection area of each pixel of the display element is discretely projected on the screen. A technology characterized by is shown.

Further, JP-A-6-324320 includes image display means for displaying an image by causing each of a plurality of pixels arranged in the vertical and horizontal directions to emit light in accordance with a display pixel pattern. An optical member for changing the optical path for each field is arranged between the image display means and an observer or a screen, and the display pixel pattern in a state where the display position is shifted according to the change of the optical path for each field. By displaying on the image display means
A technique has been disclosed in which the resolution of a display image is apparently improved without increasing the number of pixels of an image display device including a (liquid crystal display). In this case, the optical path is changed by alternately making the portions having different refractive indexes appear in the optical path between the image display device and the observer or the screen for each field of the image information. Further, Japanese Patent Application Laid-Open No. 8-29779 discloses a technique that enables a high-definition image to be displayed using a low-resolution display element and improves the contrast on a polarizing screen for improving the contrast. It is shown.
In this case, the polarization plane of the display light from the LCD is rotated by the first polarization plane rotating element for each field, the optical path of one field is shifted with respect to the other by passing through the birefringent optical element, and it is apparent. Increase pixels.

Further, a second optical element is provided at the latter stage of the birefringent optical element.
By arranging the polarization plane rotating element, the polarization plane emitted from the birefringent optical element is rotated in the opposite direction to the polarization plane of the display light in one field, and the polarization plane is changed to a normal vertical plane. Are returning. Furthermore, JP-A-10-550
Japanese Patent Publication No. 29 relates to a projection type display device for displaying an image of one frame by dividing it into a plurality of fields, and has a simple configuration without lowering the light transmittance or contrast even if an optical modulator having a small number of pixels is used. , A projection display device capable of time-division display and displaying an image with high resolution is shown. In this case, by driving the actuator in synchronization with the field signal supplied to the light modulation element, the microlens array is moved or vibrated in the horizontal / vertical direction orthogonal to the optical axis of the light incident on the microlens array.

[0005]

On the other hand, in the prior art of the control method of the optical path deflecting element and the image display device described above,
In general, a liquid crystal material has a property that the refractive index varies depending on the wavelength, that is, has a wavelength dispersion characteristic. Therefore, when a liquid crystal material is used as an optical element (optical path deflecting element), it depends on the wavelength of incident light entering the optical element. , The optical path shift amount fluctuates,
Therefore, there is a problem in that the position of the dot is displaced in the color of the display image projected on the screen. It should be noted that in the above-mentioned "projection display device" of Japanese Patent Laid-Open No. 2939826, the shift amount of the projected image varies depending on the wavelength of light, and the resolution is likely to decrease. In addition, JP-A-6-3243
In "Image Display Device, Resolution Improvement Method of Image Display Device, Imaging Device, Recording Device, and Reproduction Device" of Japanese Patent Publication No. 20,
As a concrete means for changing the optical path, a device including a combination mechanism of an electro-optical element and a birefringent material, a lens shift mechanism, a vari-angle prism, a rotating mirror, a rotating glass, etc. is shown. , A method of switching the optical path by displacing (translating, tilting) an optical element such as a lens, a reflection plate, and a birefringent plate by a voice coil, a piezoelectric element, etc. has been proposed. Driving the drive complicates the configuration and thus increases the cost.

Further, in the "optical wobbling display device by polarization rotation" disclosed in Japanese Patent Application Laid-Open No. 8-29779, in addition to the birefringent optical element, a second polarization plane rotating element after the birefringent optical element is required. Therefore, the cost increases. Further, in the "projection type display device" of Japanese Patent Application Laid-Open No. 10-55029, as the optical path modulating means, the microlens array is physically moved or vibrated in the horizontal / vertical direction orthogonal to the optical axis of the incident light, so that the vibration is generated. , Sound generation becomes a problem. Further, in the text of Japanese Patent Application Laid-Open No. 10-55029, "In this embodiment, the microlens array 4 corresponding to a plurality of pixels is moved and changed, but the light emitted from a plurality of adjacent pixels of the light modulation element is changed. Since there is only a condensing unit in which a plurality of condensing optical elements included in each aperture are arranged adjacent to each other, and a unit for changing the projection area so as to interpolate the projection image made discrete by the condensing unit, for example, References ("Sato Susumu; Variable Focus Lens Using Liquid Crystal", Opto-Technical Contact, Vol 32, No. 11, p. 24 to p. 28, 1
994) using a liquid crystal lens as disclosed in
The voltage may be selectively applied in synchronization with the field signal to change the formation position of the lens. "

However, in the liquid crystal microlens array having the circular hole-shaped pattern described in the above-mentioned document, it is relatively easy to change the focal length in the optical axis direction, but the focusing position in the arrangement direction of the lens array. Cannot be changed. Incidentally, as a technique for solving this point, as a technique for controlling the condensing position in the array surface direction of the lens, Japanese Patent Laid-Open No. 11-
Japanese Patent Laid-Open No. 109304 discloses a method using divided electrodes. However, when the liquid crystal lens having the divided electrodes is formed into an array, the electrode wiring becomes complicated, and therefore the lens formation interval must be set relatively wide. Therefore, it is suitable when the installation intervals of the lenses may be relatively wide, as in the case of using a combination of a semiconductor laser array and a plurality of optical fibers as disclosed in JP-A-11-109304. Japanese Patent Laid-Open No. 10-550
There is a problem that the aperture ratio of the lens forming portion becomes small when the lens forming interval is relatively small like the pixel pitch of the image display element disclosed in Japanese Patent No. 29.

The present invention has been made in view of the above-mentioned circumstances, and controls the voltage applied to the transparent electrode to perform the optical path shift corresponding to the wavelength range of the transmitted light, thereby apparently increasing the display pixel and increasing the optical path. It is an object of the present invention to provide an optical path deflecting element capable of maintaining a uniform shift amount. An object of claim 1 of the present invention is to provide an optical path deflecting element capable of correcting the wavelength dispersion of light and making the optical path shift amount constant. The object of claim 2 of the present invention is to
In particular, it is an object of the present invention to provide an optical path deflecting element that makes the optical path shift amount uniform even when wavelengths in different wavelength regions are incident on the optical path deflecting element. It is an object of claim 3 of the present invention to provide an optical path deflecting element which makes the optical path shift amount constant even when spatially different wavelengths are incident on the optical path deflecting element.

An object of a fourth aspect of the present invention is to provide an optical path deflecting element which makes the optical path shift amount constant even when spatially divided and different wavelengths are incident. It is an object of claim 5 of the present invention to provide an optical path capable of controlling the transmitted light deflection amount at a resolution higher than the pixel pitch of the incident side pixels and correcting the positional deviation of dots due to the color of the display image. It is to provide a deflection element.
An object of claim 6 of the present invention is to provide a relatively small-sized image display device, in particular, which corrects the positional deviation of dots due to the color of the displayed image even when the field sequential system is used. The object of claim 7 of the present invention is to
In particular, it is an object of the present invention to provide a method of controlling an optical path deflecting element, which can correct a positional deviation of dots due to a difference in color of a display image and can apparently multiply the number of pixels of the display image.

[0010]

In order to achieve the above-mentioned object, an optical path deflecting element according to the present invention according to claim 1 comprises a pair of transparent substrates and a liquid crystal layer between the pair of transparent substrates. In an optical path deflection element having a transparent electrode for applying an electric field to the liquid crystal layer, an optical path deflection voltage for applying different applied voltages to each of the plurality of transparent electrodes corresponding to a wavelength range of incident light on the liquid crystal layer. It is characterized by having a control means. Further, the optical path deflection voltage control means of the optical path deflection element according to the present invention described in claim 2 is configured so that, when light in a plurality of different wavelength ranges is incident on the optical path deflection element while being sequentially switched in time, each wavelength range is changed. Correspondingly, it is characterized in that the value of the applied voltage is sequentially switched in time. In order to achieve the above-mentioned object, an optical path deflecting element according to a third aspect of the present invention includes a pair of transparent substrates,
A liquid crystal layer between the pair of transparent electrodes, and a transparent electrode for applying an electric field to the liquid crystal layer, in the optical path deflecting element to which light in a plurality of different wavelength regions is incident in a spatially distributed state,
A plurality of regions corresponding to respective wavelength regions are formed, and condition setting means for setting different optical path deflection conditions for each of the regions is provided.

The condition setting means of the optical path deflecting element according to the present invention according to claim 4 is characterized in that it has optical path deflection voltage control means for setting a different applied voltage for each region. An image display device according to the present invention according to claim 5 is an image display device in which a plurality of light-controllable pixels are two-dimensionally arranged in accordance with at least image information in order to achieve the above object, and the image. A light source for illuminating a display element, an optical member for observing an image pattern displayed on the image display element, and a space between the image display element and the optical member for each of a plurality of subfields obtained by temporally dividing an image field. The optical path deflecting element according to claim 1, 2, 3 or 4 for deflecting the optical path of, and displaying an image pattern in a state in which the display device is displaced according to the deflection of the optical path for each subfield. It is characterized in that the apparent number of pixels of the image display element is multiplied and the positional deviation of dots due to the color of the displayed image is corrected and displayed.

An image display device according to the present invention according to claim 6 has a light source or a wavelength switching means for irradiating the image display element while sequentially switching light in a plurality of different wavelength ranges in time, and each wavelength In an image display device that obtains a color image by driving the image display element using an image signal corresponding to, the optical path deflection voltage control for changing the voltage applied to the optical path deflection element in synchronization with the switching timing of each wavelength. It is characterized by having means. In order to achieve the above-mentioned object, the method for controlling an optical path deflecting element according to the present invention according to claim 7 applies a pair of transparent substrates, a liquid crystal layer between the transparent substrates, and an electric field to the liquid crystal layer. In a method of controlling an optical path deflecting element having a transparent electrode for applying, a voltage value of an applied voltage applied to the transparent electrode is controlled in accordance with a wavelength range of liquid crystal light passing through the liquid crystal layer and the transparent electrode. It is characterized by that.

[0013]

That is, the optical path deflecting element according to claim 1 of the present invention is an optical path deflecting element having a pair of transparent substrates, a liquid crystal layer between the pair of transparent substrates, and a transparent electrode for applying an electric field to the liquid crystal layer. A different voltage is applied to each of the plurality of transparent electrodes by the optical path deflection voltage control means corresponding to the wavelength range of the incident light on the liquid crystal layer.
With such a configuration, the deflection characteristics of the optical path deflecting element are set separately for each wavelength range of the incident light, and the chromatic dispersion of light for each wavelength range is corrected, so that the optical path shift amount can be kept constant. it can. Further, the optical path deflection voltage control means of the optical path deflection element according to claim 2 is such that when a plurality of lights in different wavelength bands are incident on the optical path deflection device while being sequentially switched in time, the applied voltage corresponding to each wavelength band is applied. Is configured to be sequentially changed over time. With this configuration, when each wavelength range of incident light is time-divided and incident,
Since the value of the applied voltage is switched according to each wavelength,
The amount of optical path shift in each wavelength range can be surely made uniform.

An optical path deflecting element according to a third aspect of the present invention has a pair of transparent substrates, a liquid crystal layer between the pair of transparent electrodes, and a transparent electrode for applying an electric field to the liquid crystal layer. In the optical path deflecting element in which the light is incident in a spatially distributed state, the condition setting means forms a plurality of regions corresponding to the respective wavelength regions, and different optical path deflection conditions can be set for each region. is there. With such a configuration, the optical path deflecting element is set under the condition that the optical path deflection is constant in a plurality of regions corresponding to the respective wavelength regions of the incident light, so that the optical path shift amount can be constant.
Further, the condition setting means in the optical path deflecting element according to the fourth aspect has an optical path deflection voltage control means for setting a different applied voltage for each region. With such a configuration, the optical path deflecting element is set under the condition that the optical path deflection is constant in a plurality of regions corresponding to the respective wavelength regions of the incident light, so that the optical path shift amount can be constant.

An image display device according to a fifth aspect of the invention is an image display device in which a plurality of light-controllable pixels are two-dimensionally arranged in accordance with at least image information, a light source for illuminating the image display device, and An optical member for observing an image pattern displayed on the image display element, and an optical path between the image display element and the optical member is deflected for each of a plurality of subfields obtained by temporally dividing the image field. Having an optical path deflecting element described in 2, 3, or 4,
By displaying an image pattern in which the display device is displaced according to the deflection of the optical path for each subfield, the apparent number of pixels of the image display element is multiplied and the dot position shift due to the color of the display image. Is corrected and displayed. With such a configuration, since a voltage corresponding to the wavelength range of the light incident on the optical path deflecting element is applied to the optical path deflecting element, and the optical path deflecting element capable of making the optical path shift amount constant is provided, It is possible to multiply the number of pixels of the display image and correct the positional deviation of dots due to the color of the display image.

An image display device according to a sixth aspect of the invention has a light source or a wavelength switching means for irradiating the image display element while sequentially switching light of a plurality of different wavelength ranges in time, and an image corresponding to each wavelength. In an image display device that obtains a color image by driving the image display element using a signal, the voltage applied to the optical path deflection element is changed in synchronization with the switching timing of each wavelength by the optical path deflection voltage control means. Configured. With this configuration,
By the field sequential method, each wavelength region of the incident light to the optical path deflecting element is time-divided, and the value of the applied voltage is switched corresponding to each wavelength to have an optical path deflecting element that keeps the optical path shift amount uniform. Therefore, it is possible to correct the positional deviation of the dots due to the color of the display image and to downsize the device. A method of controlling an optical path deflecting element according to claim 7, wherein the optical path deflecting element has a pair of transparent substrates, a liquid crystal layer between the transparent substrates, and a transparent electrode for applying an electric field to the liquid crystal layer. The voltage value of the applied voltage applied to the transparent electrode is controlled in accordance with the wavelength range of liquid crystal light passing through the liquid crystal layer and the transparent electrode. With such a configuration, it is possible to apparently multiply the number of pixels of the display image and correct the positional deviation of the dots due to the difference in color of the display image.

The present invention may be configured as follows. That is, the optical path deflecting element of the present invention is an optical path deflecting element comprising a pair of transparent substrates, a liquid crystal layer between the transparent substrates, and a transparent electrode for applying an electric field to the liquid crystal layer, wherein the transparent electrode is a liquid crystal. Install so that it touches the layer side. With such a configuration, a control electric field effect can be effectively exerted on the liquid crystal layer. In the optical path deflecting element of the present invention, the transparent electrode is provided in at least one of the pair of transparent substrates.
They are arranged on one surface and are formed in an array corresponding to the pixel pitch of the incident side pixels. With such a configuration, it is possible to control the transmitted light deflection amount with a resolution that maintains the pixel pitch of the incident side pixels. In the optical path deflecting element of the present invention, the transparent electrode is provided on at least one surface of the pair of transparent substrates, and the pitch of the transparent electrode is an integral multiple of the pixel pitch of the incident side pixels, or an integer It is formed in conformity with 1. With such a configuration, it is possible to control the transmitted light deflection amount with a desired resolution based on the pixel pitch of the incident side pixels.

In the optical path deflecting element of the present invention, the transparent electrodes are placed in contact with at least one surface of the pair of transparent substrates, and a plurality of transparent electrode lines are arranged as a set, and the transparent electrodes are arranged. The set of lines is formed corresponding to the pixel pitch of the incident side pixels. With such a configuration, it is possible to control the transmitted light deflection amount with a resolution higher than the pixel pitch of the incident side pixels. The optical path deflecting element of the present invention is
Conductivity is imparted to the transparent substrate, and the transparent electrode is substituted for the transparent electrode. With such a configuration, the cost can be reduced. In the optical path deflecting element of the present invention, the liquid crystal molecules of the liquid crystal layer are preliminarily homogeneously aligned so that they are parallel to each other along the transparent substrate when the liquid crystal layer has no electric field. By such preprocessing, control of the transmitted light deflection amount can be easily executed. In the method of controlling the optical path deflecting element of the present invention, the voltage value of the applied voltage applied to the transparent electrode is increased in accordance with the increase in the frequency of the liquid crystal light passing through the liquid crystal layer and the transparent electrode. With such a configuration, it is possible to correct the dot positional deviation due to the difference in the color of the display image with a simple voltage control means.

In the control method of the optical path deflecting element of the present invention, the voltage value of the applied voltage applied to the transparent electrode is controlled in accordance with the optical path deflecting condition set for each region. With such a configuration, the physical characteristics of the optical path for each area can be considered, and the transmitted light deflection amount can be uniformly controlled in accordance with the wavelength range of the incident light for each area. Further, the image display device of the present invention is an image display device for enlarging and displaying an image displayed on an image display element having a plurality of pixels on a screen via an optical path deflecting element for deflecting transmitted light, The optical path of the light passing through the deflecting element is divided into a plurality of subfields, and the optical path deflection voltage control means is provided for controlling the deflection amount of the light passing through the subfield according to the wavelength of the light. With such a configuration, it is possible to realize an image display device that displays an image displayed by the image display element on the screen at a desired resolution based on the pixel pitch of the image display element. Further, the image display device of the present invention, in synchronization with the switching timing of the wavelength of the light transmitted through the optical path deflecting element,
The voltage value of the control voltage is changed. With such a configuration, it is possible to realize an image display device that apparently multiplies the number of pixels of a display image and corrects the positional deviation of dots due to the difference in color of the display image.

The image display device of the present invention corresponds to the light source or the wavelength band switching means for irradiating the image display element while sequentially switching light of a plurality of different wavelength bands in the image display device, and the wavelength band. Display driving means for driving the image display element using the image signal.
With such a configuration, it is possible to correct the positional deviation of the dots due to the difference in the color of the display image from the image display element adopting the so-called field sequential method, and to downsize the device. In the image display device of the present invention, the optical path deflection element has an optical path deflection voltage control means for changing a deflection amount of light passing through the subfield in accordance with a voltage value of a control voltage corresponding to the subfield. .
With such a configuration, an image display device capable of controlling the transmitted light deflection amount corresponding to the wavelength range of the incident light in each subfield while considering the physical characteristics of the optical path in each subfield is realized. can do.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An optical path deflecting element and an image display device of the present invention will be described below with reference to the drawings based on the embodiments of the present invention. FIG. 1 is a configuration diagram showing a configuration of a main part of an image display device according to a first embodiment of the present invention.
The image display device shown in FIG. 1 includes a light source drive unit 111, a display drive unit 112, an optical path deflection voltage control unit 113, an image display control circuit 114, a white lamp 121, a diffusion plate 122, and
Condenser lens 123, transmissive liquid crystal light valve 12
4, an optical path deflecting element 125, a projection lens 126 and a screen 127. Of these, the light source driving unit 111 drives and controls the white lamp 121, which is a light source, and controls the transmission type liquid crystal light valve 124 while irradiating the light of a plurality of different wavelength regions sequentially. . Further, the display driving means 112 drives and controls a transmissive liquid crystal light valve 124 which is an image display element,
For example, the light valve 124 is driven and controlled using an image signal corresponding to each wavelength. Further, the optical path deflection voltage control means 113 controls the voltage applied to the optical path deflection element 125.

For example, different voltages are applied to each of the plurality of transparent electrode arrays 312 corresponding to the wavelength range of the incident light on the liquid crystal layer 313. Further, the image display control circuit 114 controls the drive timing of the light source drive means 111, the display drive means 112, and the optical path deflection voltage control means 113. The white lamp 121 functions as a backlight, that is, a light source for illuminating the transmissive liquid crystal light valve 124 which is an image display element. In addition, the diffusion plate 122 converts the light emitted from the white lamp 121 into uniformed illumination light. Further, the condenser lens 123 is provided in the diffusion plate 12.
The illumination light obtained in 2 is transmitted through the liquid crystal light valve 124.
Is converted into illumination light that can be illuminated critically.
The transmissive liquid crystal light valve 124 is a condenser lens 1.
It functions as an image display element that converts the illumination light obtained in 23 into image light. Further, the optical path deflecting element 125 shifts the image light obtained by the transmissive liquid crystal light valve 124 by an arbitrary distance in the pixel arrangement direction. Further, the projection lens 126 as an optical member magnifies the image light that has passed through the optical path deflecting element 125 and projects it on the screen 127.
The screen 127 converts the image light that has passed through the projection lens 126 into an image.

Although the white lamp 121 is shown as the light source in the first embodiment, in general, any light source that can turn on / off light of white or any color at high speed can be used. Is. For example, LE
It is possible to use a D (light emitting diode) lamp, a laser light source, or a white lamp light source combined with a shutter. In addition, in the first embodiment,
Although the transmissive liquid crystal light valve 124 is shown as an image display element, generally, in the present invention, a reflective liquid crystal light valve or a DMD (Digital Micromirror Device) is used as an image display element in addition to the transmissive liquid crystal light valve. It is possible to use an element or the like. Further, as a device for uniformly irradiating the image display device with the light emitted from the light source, it is possible to use a flyer lens in addition to the diffuser plate 122 and the condenser lens 123 shown in the present embodiment.

The function of the image display device according to the first embodiment will be described in more detail below. The light emitted from the white lamp 121 which is a light source under the control of the light source driving means 111 having a power source or a wavelength switching means is diffused by the diffusion plate 122.
Illumination light that has been made uniform by the condenser lens 1
23, the transmissive liquid crystal light valve 124, which is an image display element, is critically illuminated. The illumination light spatially light-modulated by the transmissive liquid crystal light valve 124 is enlarged by the projection lens 126 as image light and projected on the screen 127. Here, the voltage applied to the optical path deflection element 125 arranged behind the transmissive liquid crystal light valve 124 is controlled by the optical path deflection voltage control means (hereinafter, may be simply referred to as “voltage control means”) 113. As a result, the image light is shifted by an arbitrary distance in the pixel array direction. In the first embodiment, the transmissive liquid crystal light valve 12
4, the optical path deflecting element 125 is arranged immediately after the position 4. However, in the present invention, the position where the optical path deflecting element 125 is arranged is not limited to the above-mentioned position. For example, it is arranged immediately before the screen 127. May be. However, in the case of arranging in the vicinity of the screen 127, the size of the optical path deflecting element 125, the transparent electrode pitch (not shown) which is a constituent element of the optical path deflecting element 125, and the like are the screen size and the pixel size at that position. The size is set according to the above, which leads to increase in size and cost.

In any case, it is preferable that the shift amount of the image light is 1 / integer of the pixel pitch.
For example, when performing image multiplication of 2 times in the pixel arrangement direction, it is set to 1/2 of the pixel pitch, and when performing pixel multiplication of 3 times, it is set to 1/3 of the pixel pitch. It is preferable. Further, when a large shift amount can be obtained by the configuration of the optical path deflection voltage control unit 113, this shift amount may be set to a length of (integer multiple + 1 / integer) of the pixel pitch. In either case, the transmissive liquid crystal light valve 124 is driven by using the image signal of the subfield corresponding to the pixel shift position, and the optical path deflection voltage control is performed according to the wavelength of the light incident on the optical path deflection element 125. Means 113
In this way, the voltage control is performed, and as a result, the optical path shift amount can be kept constant as shown in FIG. Figure 2
FIG. 3 is a configuration diagram showing a pixel configuration of an image obtained by the image display device according to the first embodiment.

In the image display device according to the first embodiment, as shown in FIG. 2, in addition to the actual pixel 2a (shown by a solid line rectangle), an apparent pixel 2b (broken line rectangle) is displayed. The effect of multiplication by () is obtained, and it is possible to display a high-definition image having a resolution higher than that of the light valve used without chromatic aberration. The transmissive liquid crystal light valve 124 shown in FIG. 1 can be configured by combining color filters. Further, it is possible to display a full-color image even by adopting a field sequential system in which a single-plate image display element is sequentially illuminated with three primary color lights. At this time, a white lamp light source and a rotating color filter may be combined to generate light of three primary colors sequentially with a time shift. Further, as the optical path deflection voltage control means 113 shown in FIG. 1, it is possible to use a liquid crystal cell whose refractive index distribution can be controlled by applying a voltage. Further, as this liquid crystal cell, a liquid crystal cell in the second embodiment is used. It is also possible to use the optical path deflecting element shown.

FIG. 3 is a sectional view of each state of an optical path deflecting element according to the second embodiment of the present invention. Of these, Figure 3
FIG. 9A schematically shows the structure of the optical path deflecting element according to the second embodiment when it is not in operation. 3B and 3C schematically show the structure of the optical path deflecting element according to the second embodiment at the time of operation, and only the transparent electrodes in the transparent electrode array 312 are shaded. The structure when a voltage equal to or higher than a threshold value is applied (that is, at each operation of the optical path deflecting element) is schematically shown. This second embodiment corresponds to claim 1 of the present invention. FIG. 3 (a),
The optical path deflecting elements shown in (b) and (c) are a pair of transparent substrates 311 and 315, a transparent electrode array 312 connected to one of the transparent substrates 311, and the transparent electrode array 31.
The liquid crystal layer 313 is sandwiched between the liquid crystal layer 2 and the transparent electrode 314. There are a plurality of transparent electrode arrays 312, each of which is formed by the above-described optical path deflection voltage control means 113 or the like.
It is assumed that different voltages can be applied. To realize this request, a wiring circuit that supplies an applied voltage can be installed as a separate system for each transparent electrode array 312.

The transparent electrode array 312 includes a transparent substrate 311.
Are formed in the lower part of the array in an array corresponding to the pixel pitch. The refractive index distribution of the liquid crystal layer 313 is controlled by applying a voltage between the transparent electrode array 312 and the transparent electrode 314. The material of the transparent substrates 311 and 315 can be glass, plastic or the like. In addition, the transparent electrode 3
For the material of 14, ITO (Indium Tin Oxide) or the like can be used. The transparent electrode 314 is installed so as to be in contact with the liquid crystal layer side. In addition, the substrate (here, the transparent substrate 311,
In the case where 315) itself has conductivity, this substrate can also be used as an electrode. Transparent electrode array 3
The pitch of 12 is not limited to the case where there is a one-to-one correspondence with the pixel pitch, but it may be matched with an integer multiple or a fraction of the pixel pitch in order to obtain a predetermined refractive index distribution. Let's be good. In addition, it is also possible to make a plurality of transparent electrode lines into one set and make the set correspond to the pixel pitch.

The surface of the transparent electrode 314 in contact with the liquid crystal layer is preferably treated so that the liquid crystal molecules are aligned. For this alignment treatment, a normal alignment film such as polyimide used for TN liquid crystal, STN liquid crystal or the like can be used. Further, it is preferable to perform rubbing treatment or photo-alignment treatment. Furthermore, an insulating film may be provided on the surface of the transparent electrode 314. As a liquid crystal material forming the liquid crystal layer 313, a general nematic liquid crystal can be used, but it is preferable that the birefringence Δn and the dielectric anisotropy Δε are large. Particularly, it is preferable that the ordinary light refractive index of the liquid crystal material is about 1.5 to 1.6, which is close to the refractive index of the glass substrate, and the extraordinary light refractive index is about 1.7 to 1.8. The thickness of the liquid crystal layer 313 is set according to the thickness of the spacer member between the transparent substrates 311 and 315, and is optimized so that a predetermined optical path deflection amount and response speed can be obtained according to Δn and Δε described above. I shall. The spacer member is preferably provided only in the peripheral portion of the liquid crystal layer so as not to hinder the transmission of light.

In the optical path deflecting element shown in FIG. 3A, the liquid crystal molecules are homogeneously aligned along the transparent substrate 311 in the absence of an electric field (here, the long axis of the liquid crystal molecules is aligned). Is supposed to be oriented in the left-right direction of the paper). As described above, the transparent electrode lines 312 are formed in an array on the lower portion of the transparent substrate 311 (here, two electrode lines having wide intervals are set as one set and correspond to one pixel. It should be noted that the portion where the interval between the electrode lines is narrow corresponds to the boundary portion between pixels). Although the transparent electrode 314 is formed on the entire surface of the element here, as shown in FIG. 22, the transparent electrode line 312 is formed.
It may be an array electrode which is symmetrical with. Figure 3 (b)
Shows schematically the structure in which the optical path deflecting element (corresponding to the operating state a) applies a voltage equal to or higher than the threshold value to only the transparent electrode lines 312 shown by hatching among the transparent electrode lines 312. In the electrode part to which a voltage is applied, the liquid crystal molecules are vertically aligned by the action of the electric field, and in the electrode part to which no voltage is applied, the liquid crystal molecules remain horizontally aligned. By the distribution of the orientation direction due to the action of the non-uniform electric field existing inside this optical path deflecting element,
A refractive index distribution for extraordinary light occurs.

FIG. 4 shows the relationship between the position of the liquid crystal layer in the direction along the transparent electrode and the refractive index in the operating states (a) and (b) of the optical path deflecting element according to the second embodiment of the present invention. It is a graph shown. When linearly polarized light having parallel polarization planes on the paper surface is incident, the effective refractive index becomes smaller as the long axis of the liquid crystal molecules is oriented perpendicular to the substrate, and the solid line graph (corresponding to operating state a) shown in FIG. It is affected by such a refractive index distribution. In addition, the polarized light that enters the central portion of each of the pixels configured as described above from the lower portion to the upper portion is deflected to the left side as shown in FIG. 3B due to the refraction effect due to the inclination of the refractive index. The optical path deflecting element (operating state b) shown in FIG.
3) is obtained by switching the electrode to which a voltage is applied in the transparent electrode array 312 of the optical path deflecting element shown in FIG. 3B to the adjacent transparent electrode. The orientation state also changes, and changes to a refractive index distribution as shown by the broken line graph (corresponding to the operating state b) shown in FIG. In this case, the polarized light that has entered the central portion of each of the pixels configured as described above from the lower portion to the upper portion is deflected to the right as shown in FIG. 3C by the refraction effect due to the inclination of the refractive index.

The rate of change of the refractive index at this time is optimized by the physical properties of the liquid crystal material and the electric field. In the pixel shift method, it is preferable to set the subframe time to 10 msec or less, and therefore a response time of several msec or less is required. When a nematic liquid crystal is used, high speed response may be achieved by using a dual frequency driving method. When the two-frequency driving method is used, it is necessary to use a driving method in which voltages having different driving frequencies can be applied to one transparent electrode line. When using this optical path deflection element, either drive method,
By alternately switching the operating state a and the operating state b by the optical path deflection voltage control means 113 in accordance with the drive timing of the sub-frame displayed on the liquid crystal light valve,
It is possible to obtain an apparent pixel multiplication effect as shown in FIG. However, this deflection amount also changes depending on the difference in the wavelength of the incident light. 22 and 23 are sectional views schematically showing the structure of the optical path deflecting element according to the third and fourth embodiments of the invention. In the optical path deflecting element shown in FIG. 3, only the transparent electrodes below the upper transparent substrate 311 are formed as a transparent electrode array 312 in an array shape.
In the third embodiment shown in FIG. 2, the transparent electrode array 312 is formed on both upper and lower substrates.

In the fourth embodiment shown in FIG. 23, an electrode array 316 is added as shown by the shaded area,
In order to further finely adjust the electric field distribution in the liquid crystal layer, an auxiliary voltage is applied to change the wavelength. Further, in the optical path deflecting element according to the fourth embodiment shown in FIG. 23, the auxiliary electrode array 31 is provided for each pixel.
6 are added one by one, but in order to adjust the refractive index distribution more finely, a plurality of pixels are added per pixel, and the wavelengths are added to these added auxiliary electrode arrays 316. The applied voltage may be changed stepwise by. FIG. 5 shows a first control method of an optical path deflecting element according to a second embodiment of the present invention, and schematically shows an optical path when light emitted from four pixels of a liquid crystal light valve enters a liquid crystal cell. FIG. In FIG. 5, for example, when the four incident side pixels 55 are in the states a, c, e, and g in the first sub-frame, the liquid crystal cell 53 (corresponding to the optical path deflecting element of the present invention) operates as shown in FIG. In the state a, the light from each of the incident side pixels incident on the lower surface of the liquid crystal cell 53 is deflected to the left as it goes upward. Further, in the second sub-frame, when the four incident side pixels 55 are switched to the states of b, d, f and h, respectively, and the liquid crystal cell 53 is switched to the operating state b of FIG. Light from each of the incident side pixels that has entered the lower surface is deflected to the right as it travels upward.

In the method of controlling the optical path deflecting element according to the third embodiment, the subframe is from several tens Hz to several hundreds Hz.
By switching with, the light traveling obliquely in the liquid crystal cell 53 is apparently a, b, c, on the upper surface of the liquid crystal cell 53.
Eight emission side pixels 51 arranged along d, e, f, g and h are output. An optical element may be provided so that the light emitted from the liquid crystal cell 53 becomes parallel to the optical axis of the projection optical system. FIG. 6 shows a method for controlling an optical path deflecting element according to a third embodiment of the present invention, which schematically shows the relationship between the wavelength of transmitted light and the amount of deflection when the voltage applied to the transparent electrode is not controlled. FIG. FIG. 7 shows a method for controlling an optical path deflecting element according to a third embodiment of the present invention, which shows the relationship between the wavelength of transmitted light and the amount of deflection when the voltage applied to the transparent electrode is controlled. It is explanatory drawing which shows typically.

Further, FIG. 8 is for explaining the control method of the optical path deflecting element according to the third embodiment of the present invention, and schematically shows the correspondence relationship between the pixel and the pixel of the liquid crystal light valve. It is an explanatory view shown. As described above, the deflection amount of light changes depending on the difference in wavelength. For example, when the liquid crystal layer 313 is in the state a of FIG. 3 as shown in FIG. 6, the light of the incident side pixels 55 (indicated by symbols R, G, and B) of the three primary colors having different wavelengths is incident light. When the light is incident on each of the lower surfaces, the shift amount of the emission-side pixel 51 changes depending on each color, and the dot position shift occurs due to the color difference. FIG. 6 shows that the deflection amount increases in the order of R, G, and B. As described above, different voltages can be applied to each of the plurality of transparent electrodes 312. Therefore, by adopting voltage control means for applying different voltages to each of the plurality of transparent electrodes 312, it is possible to make the deflection amount constant and correct the dot positional deviation due to the color difference.

In the case where a color filter is fitted to the liquid crystal light valve in order to display a full-color image with the structure of the present invention, one of the liquid crystal light valve is provided as shown in FIG.
Each of the three primary colors (R, G, B) is formed in the pixel.
One pixel of the liquid crystal light valve 82 and one pixel of the optical path deflector 81
Since each pixel has a one-to-one correspondence and can be connected by straight lines in the same direction, light of a predetermined wavelength is incident on a predetermined position on the optical path deflecting element. As shown in FIG. 3, the refractive index distribution changes depending on the alignment state of the liquid crystal, and the light is deflected. As shown in FIG. 6, the deflection amount changes depending on the wavelength of the transmitted light. Each wavelength (color)
By controlling the voltage for each, the amount of deflection can be made constant. FIG. 7 shows a voltage control method for correcting the deflection amount constant. Wavelength dispersion of the liquid crystal, the refractive index as the wavelength is increased (prolonged) have a smaller tendency to voltage due to red polarization V _R, the voltage due to the green polarization V _G, the blue polarized light When the resulting voltage is V _B , the deflection amount of each color becomes constant by controlling the voltage so that V _R ≦ V _G ≦ V _B.

However, since the chromatic dispersion varies depending on the type of liquid crystal, the voltage value of the applied voltage is set to a value suitable for each type of liquid crystal by the condition setting means (not shown) including the optical path deflection voltage control means 113. Select and set. A filter or the like may be used as a means for keeping the deflection amount constant, and the deflection amount may be controlled by changing the refractive index of the emitted light. The electrode structure and the thickness of the liquid crystal layer may be set to suitable conditions. You may control it. Note that, as shown in FIG. 5, when only the light direction can be changed by the liquid crystal cell 53, it is necessary to adjust the pixel size on the incident side to be small according to the pixel size on the emitting side. As a method of adjusting the pixel size on the incident side, a method of regulating the optical path through a mask having an opening corresponding to the pixel position, a method of collecting light with a microlens array corresponding to the pixel position, or the like can be applied. However, the method of using a mask lowers the light utilization efficiency, and the method of condensing with a microlens array requires a new microlens array, which increases the cost. Therefore, in another configuration of the optical path deflecting element according to the present invention, one liquid crystal cell has a pixel size reducing function and an optical path deflecting function at the same time. FIG. 9 is a cross-sectional view for each state showing a method of controlling an optical path deflecting element according to a third embodiment of the present invention and schematically showing a structure when a pixel reducing function is added.

FIG. 10 is a graph showing the relationship between the alignment direction of the liquid crystal layer and the refractive index when the pixel reducing function is added to the optical path deflecting element according to the third embodiment of the present invention. The basic configuration such as the material used and the processing method may be the same as that of the optical path deflecting element shown in FIG. 3, but the pitch and width of the transparent electrode array 312 are different from those of the optical path deflecting element shown in FIG. In the optical path deflecting element shown in FIG. 9, the transparent electrode array 312 is formed below the upper transparent substrate 311 at the same pitch as the pixel pitch of the image display element. The width of each electrode is not particularly limited, but is set according to a desired electric field intensity distribution in the liquid crystal layer 313. FIG. 9A schematically shows the structure of the optical path deflecting element in the operating state a. In this case, the transparent electrodes arrayed in the transparent electrode array 312 are alternately arranged with respect to the transparent electrodes (electrodes shown by hatching). A voltage above the threshold is applied. By applying this voltage, a refractive index distribution is generated in the liquid crystal layer 313 as described above. This refractive index distribution has a convex lens shape with a relatively large pitch, as shown by the solid line graph (a) in FIG. 10. In this case, one convex lens effect is given to two pixels of the image display element. However, also in this case, the deflection amount changes depending on the wavelength.

Here, an explanatory view similar to that of FIG. 5 is shown in FIG. FIG. 11 shows a method for controlling an optical path deflecting element according to a third embodiment of the present invention, in which light emitted from four pixels of a liquid crystal light valve enters a liquid crystal cell when a pixel reducing function is added. It is explanatory drawing which shows the optical path in a case typically. In the present invention, the size of the incident side pixel 55 that enters the liquid crystal cell 53 (corresponding to the optical path deflecting element of the present invention) is set to be relatively large. Four incident side pixels 5 shown in FIG.
When the states of a, c, e, and g are displayed in 5 as the first subframe, a and c and e and g are reduced by the refractive index distribution of the solid line graph shown in FIG. At this time, the pixel pitch is not constant like the output side pixel 51 shown by the solid line in the upper part of FIG. Next, as shown in FIG. 9B, when the transparent electrodes to which a voltage is applied are switched in the transparent electrode array 312 in accordance with the display timing of the second sub-frame, the refractive index distribution becomes as shown in FIG. Switching is performed as shown by a broken line graph (b).

Here, when the incident side pixel 55 displays the states of b, d, f and h as the second sub-frame, it is reduced to the position of the emitting side pixel 51 shown by the broken line in the upper part of FIG. The pixel thus moved moves. By switching the sub-frames from several tens Hz to several hundreds Hz, apparently b, a, c, d, f, e, g, h are arranged irregularly on the upper surface of the liquid crystal cell 53. It becomes one pixel. As described above, also in this case, the deflection amount changes depending on the wavelength. FIG. 12 shows the wavelength of the transmitted light and the amount of deflection when the correction control of the voltage applied to the transparent electrode is not performed in the case where the pixel reduction function is added to the optical path deflection element according to the third embodiment of the present invention. It is explanatory drawing which shows the relationship with. FIG. 13 shows the wavelength of transmitted light and the amount of deflection when correction control of the voltage applied to the transparent electrode is performed when the pixel reduction function is added to the optical path deflection element according to the third embodiment of the present invention. It is explanatory drawing which shows the relationship of. For example, in the operation state a shown in FIG. 9A as shown in FIG. 12, when light of three primary colors having different wavelengths is incident on each position of the liquid crystal cell 53 as incident light, the pixel size on the emission side is changed. It is not constant, and the dot position shifts due to the difference in color.

In the case of the voltage control method shown in FIG. 13, V _R ≤ V _{G is} applied to the electrodes caused by the polarization of each color of the optical path deflecting element.
By applying and controlling a voltage such that ≦ V _B , the deflection amount becomes constant, and the dot misregistration due to the color difference is corrected. In order that a display image by such an irregular pixel shift is formed as a normal image, the data of the subfield image is corrected on the image display element and the optical path shift amount is adjusted by controlling the voltage of the optical path deflection element. Pixels can be displayed with constant.
In the third embodiment, with a simple electrode configuration, one pixel liquid crystal cell can achieve both the pixel reduction effect by condensing the liquid crystal lens and the pixel shift effect by switching the liquid crystal lens formation position. Therefore, with a simple element configuration, it is possible to prevent a decrease in light utilization efficiency and correct a dot positional deviation due to a color difference. Figure 1
FIG. 4 is an explanatory view illustrating the configuration of an image display device that employs an optical path deflecting element according to a third embodiment of the present invention, for each major component.

In FIG. 14, the transparent electrode array 312 of the optical path deflecting element 81 forming the optical path deflecting means is formed in a line along the vertical direction of the paper surface. In this case, if the light emitted from the image display element 61 is linearly polarized light in the left-right direction with respect to the paper surface, the entire image display element 61 can be pixel-shifted along the left-right direction on the paper surface. Therefore, it is possible to realize a high-definition image display device that does not cause chromatic aberration in the lateral direction of the screen with a relatively simple electrode configuration. FIG. 15 is a perspective view showing a schematic structure of a field sequential system in which a single-plate image display element is time-sequentially illuminated with three primary color lights to display a full-color image. FIG. 16 is an explanatory diagram schematically showing the relationship between the wavelength of transmitted light and the amount of deflection when the voltage applied to the transparent electrode is not corrected and controlled in the field-sequential image display device.

FIG. 17 is another explanatory diagram schematically showing the relationship between the wavelength of transmitted light and the amount of deflection when the voltage applied to the transparent electrode is not corrected in the field-sequential image display device. Is. Even when a field sequential method of displaying a full-color image by illuminating a single plate image display element with three primary color lights in a time-sequential manner is used, as shown in FIGS. Therefore, as shown in FIG. 18, the deflection amount can be made constant by dividing the voltage in time and performing correction control. FIG. 18 is an explanatory diagram showing a method of correcting and controlling the voltage applied to the transparent electrode in the field-sequential image display device. FIG. 19 shows a field-sequential image display device.
It is explanatory drawing which shows typically the relationship between the wavelength of transmitted light and the deflection amount in the middle of performing the correction control of the voltage applied to a transparent electrode. FIG. 20 is an explanatory diagram that schematically shows the relationship between the wavelength of transmitted light and the amount of deflection when correction control of the voltage applied to the transparent electrode is performed in the image display device of the field sequential system according to the present invention. is there.

In FIG. 18, t on the horizontal axis indicates the time elapsed when light is incident, and the time zone when red light is incident is t.
_The time period when _R and green are incident is t _G , and the time period when blue is incident is t _B. Further, λ on the vertical axis indicates the wavelength. By applying a voltage corresponding to the wavelength range in synchronism with the timing of the time period in which each color is incident, the shift amount becomes constant as shown in FIGS. Can be corrected. Further, even when the white lamp light source and the rotary color filter are combined to generate the time-sequential three primary color light, the positional deviation of dots due to the difference in color can be corrected as in the case shown in FIGS. In the configuration shown in FIG. 11, since the optical path is the non-parallel light condensed by the liquid crystal lens, depending on the position from the exit side of the liquid crystal cell 53,
The pixel size changes anew. For example, when a diffusion plate or the like is placed on the exit side of the liquid crystal cell 53 to directly observe an image without using a projection optical system, the apparent pixel size changes when the liquid crystal cell 53 and the diffusion plate are misaligned. I will end up. Further, even when the magnifying optical system is used, it is preferable that the light emitted from the cells be parallel from the viewpoint of lens design. Therefore, in another configuration according to the fifth embodiment, it is possible to provide an optical element that allows the light emitted from the liquid crystal cell to be parallel to the optical axis of the projection optical system.

FIG. 21 shows a method of controlling an optical path deflecting element according to a fifth embodiment of the present invention, and schematically shows the arrangement of optical elements for correcting the deflection of the optical path by the liquid crystal lens array formed by the liquid crystal layer. It is an explanatory view shown. When the characteristic of the liquid crystal lens array formed by the liquid crystal layer of the optical path deflecting element is a convex lens, the aforementioned optical element is preferably a concave lens array that returns the optical path to parallel light. For example, the above-mentioned optical element may be installed at a position equal to the pixel pitch of the incident side pixels 55 and displaced by a half pixel from the incident side pixel position, as shown by the light beam collimating unit 56 in FIG. preferable. In the fifth embodiment, the light path deflecting section 57 corresponding to the liquid crystal cell 53 shown in FIG. 11 is arranged in the same manner as the light path deflecting element 81 shown in FIG. When linearly polarized light in the left-right direction with respect to the paper surface, the entire image display element can be effectively pixel-shifted in the left-right direction with respect to the paper surface. Therefore, the resolution in the horizontal direction of the screen is increased, chromatic aberration is eliminated, and a high-definition image display device with high pixel position accuracy can be realized.

[0046]

EXAMPLES Example 1 An image display apparatus according to the first embodiment as shown in FIG. 1 was created using the optical path deflecting element according to the second embodiment. As the image display element (corresponding to the transmissive liquid crystal light valve 124 in FIG. 1), a diagonally 0.9 inch XGA (1024 × 768 dots) polysilicon TFT liquid crystal panel was used. The pixel pitch is approximately 18 μm in both length and width. The pixel aperture ratio is about 50%. In addition, a microlens array is provided on the light source side of the image display element to increase the light collection rate of the illumination light. In this embodiment, a so-called field sequential method is used in which an LED light source of RGB three colors is used as a light source, and color display is performed by rapidly switching the color of the light applied to the one liquid crystal panel by the wavelength switching means. ing. Generally, when the frame frequency of the image display is 60 Hz, one frame is further divided into three colors, so that the image corresponding to each color is
I tried to switch at 80Hz. By turning on / off the LED light source of the corresponding color in accordance with the display timing of the image of each color on the liquid crystal panel, the observer can see the full-color image.

Since this system does not use a color filter and one liquid crystal panel is sufficient, it is advantageous for high definition images and miniaturization of the apparatus. In this embodiment, the field sequential method is combined with the pixel shift method. In order to double the pixel multiplication in the horizontal direction of the image, the pixel position is shifted by 120 Hz and the display time of the subfield image is set within 8.3 milliseconds. The time required to switch the optical path within this period (optical path switching time)
It includes Δt and the time when the liquid crystal panel can be used for image display. The longer the time that can be used for image display, the longer the light emission time of the LED in the field sequential system can be reduced, and the light emission brightness of the LED can be reduced, and the burden on the light source for the LED can be reduced. Therefore, the optical path switching time Δt is preferably as short as possible, and a high-speed optical path switching means is required.
In this embodiment, since it is necessary to switch the switching time as fast as 1 millisecond or less, the dual frequency driving method of the nematic liquid crystal cell was adopted. As a comparative example of the present invention, as an optical path switching means capable of high-speed operation, a method of changing the tilt angle of the refraction plate by using a swing mechanism such as a piezoelectric actuator is also possible. It may occur, which is not preferable.

The liquid crystal microlens array was prepared based on the following specifications. The ITO vapor deposition film on a thin glass substrate (3 cm × 4 cm, thickness 0.15 mm) was etched to form ITO lines having a width of 10 μm and a pitch of 18 μm. The ITO line was a comb-shaped electrode so that the same voltage could be applied alternately. A polyimide-based orientation material was spin-coated on the ITO side of the glass substrate to form an orientation film of about 0.1 μm. After the glass substrate was annealed, it was rubbed in a direction perpendicular to the ITO line. An empty cell was prepared by sandwiching a spacer having a thickness of 11 μm in the peripheral portion between the two glass substrates and adhering them so that the ITO line positions of the upper and lower substrates were aligned. A nematic liquid crystal having a positive dielectric anisotropy was injected into this cell under normal pressure to prepare a liquid crystal cell. Since the upper and lower substrates are rubbed in the same direction, all the liquid crystal molecules are aligned in the same direction as shown in FIG.

This liquid crystal cell was installed immediately after the liquid crystal light valve to adjust the alignment between the pixel position and the transparent electrode line. Further, a diffuser plate having a thin diffuser layer was fitted to the exit side of the liquid crystal cell, and the diffused light on the exit surface was enlarged and observed. When a voltage was applied to the transparent electrode lines at a ratio of 1: 1: 1 according to the timing of the red, green, and blue light incident on this liquid crystal cell, a lens effect appeared in the liquid crystal layer, and the pixel shrank. However, the reduction amount was different depending on the color. Next, when the electrode line to which a voltage was applied was switched, the position of the reduced pixel moved, but the amount of movement varied depending on the color. Therefore, 7.1: according to the timing of the incident red, green, and blue light.
When a voltage of 8.5: 9.2 was applied to the transparent electrode and the diffused light of the liquid crystal cell was observed, a good image without color unevenness was seen. The results of comparison of applied voltages are summarized in Table 1.

[0050]

[Table 1]

(Example 2) A liquid crystal lens cell was prepared in the same manner as in Example 1, and a white lamp was used as a light source.
Color display was performed through a transmissive liquid crystal light valve provided on the surface of each pixel with a color filter. The prepared liquid crystal cell was installed immediately after the liquid crystal light valve, and the alignment of the pixel position and the transparent electrode line was adjusted. Further, a diffuser plate having a thin diffuser layer was fitted to the exit side of the liquid crystal cell, and the diffused light on the exit surface was enlarged and observed. When the voltage was applied to the transparent electrode line while switching the voltage at a ratio of 1: 1: 1 according to the positions of the red, green, and blue lights incident on the liquid crystal cell, the pixel contraction and movement were observed. The same problem as in Example 1 (the reduction amount and the movement amount differ depending on the color) occurred. Therefore, a voltage of 7.1: 8.5: 9.2 was applied to the transparent electrode in accordance with the positions of the incident red, green, and blue lights, and a good image without color unevenness was seen. Was given. Table 2 shows the comparison result of the applied voltages.

[0052]

[Table 2]

In each of the above embodiments, the image display element was observed directly or through the magnifying lens system, but the same effect can be obtained by observing the image on the screen through the projection lens.

[0054]

As described in detail above, according to the optical path deflecting element according to claim 1 of the present invention, a pair of transparent substrates,
In an optical path deflecting element having a liquid crystal layer between the pair of transparent substrates and a transparent electrode for applying an electric field to the liquid crystal layer, a plurality of optical path deflecting voltage control means are provided to correspond to a wavelength range of light incident on the liquid crystal layer. Since different voltages are applied to each of the transparent electrodes, the deflection characteristics of the optical path deflecting element are set separately for each wavelength range of incident light, and the wavelength dispersion of light for each wavelength range is corrected. Therefore, the optical path shift amount can be made constant. Further, the optical path deflection voltage control means of the optical path deflection element according to claim 2 is such that when a plurality of lights in different wavelength bands are incident on the optical path deflection device while being sequentially switched in time, the applied voltage corresponding to each wavelength band is applied. Since the values of are changed sequentially in time, when the wavelengths of the incident light are time-divided and incident, the value of the applied voltage is changed corresponding to each wavelength, so the optical path shift in each wavelength range is changed. The quantity can be reliably made uniform.

An optical path deflecting element according to a third aspect has a pair of transparent substrates, a liquid crystal layer between the pair of transparent electrodes, and a transparent electrode for applying an electric field to the liquid crystal layer, and has a plurality of different wavelength ranges. In the optical path deflecting element in which the light enters in a spatially distributed state, the condition setting means forms a plurality of regions corresponding to the respective wavelength regions, and different optical path deflection conditions can be set for each region. Since the optical path deflecting element is set under the condition that the optical path deflection is constant in a plurality of regions corresponding to the respective wavelength regions of the incident light, the optical path shift amount can be constant. Further, the condition setting means in the optical path deflecting element according to claim 4 has an optical path deflection voltage control means for setting a different applied voltage for each area, and the optical path deflection is performed in a plurality of areas corresponding to respective wavelength areas of incident light. Since the condition for keeping constant is set in the optical path deflecting element, the optical path shift amount can be made constant.

An image display device according to a fifth aspect of the present invention is an image display device in which a plurality of light-controllable pixels are two-dimensionally arranged according to at least image information, a light source for illuminating the image display device, and An optical member for observing an image pattern displayed on the image display element, and an optical path between the image display element and the optical member is deflected for each of a plurality of subfields obtained by temporally dividing the image field. Having an optical path deflecting element described in 2, 3, or 4,
By displaying an image pattern in which the display device is displaced according to the deflection of the optical path for each subfield, the apparent number of pixels of the image display element is multiplied and the dot position shift due to the color of the display image. Since the image is corrected and displayed, it is possible to multiply the number of pixels of the display image and correct the positional deviation of the dots due to the color of the display image. Further, the image display device according to claim 6 has a light source or a wavelength switching means for irradiating the image display element while sequentially switching light in a plurality of different wavelength ranges in time, and uses an image signal corresponding to each wavelength. In an image display device that obtains a color image by driving the image display element by
The optical path deflection voltage control means is configured to change the applied voltage of the optical path deflection element in synchronization with the switching timing of each wavelength, and by the field sequential method,
Each wavelength range of the incident light to the optical path deflecting element is time-divided, and the value of the applied voltage is switched according to each wavelength to have an optical path deflecting element for keeping the optical path shift amount uniform. It is possible to correct the positional deviation of the dots due to the color and to downsize the device.

A method of controlling an optical path deflecting element according to a seventh aspect is a method of controlling an optical path deflecting element having a pair of transparent substrates, a liquid crystal layer between the transparent substrates, and a transparent electrode for applying an electric field to the liquid crystal layer. In the above, since the voltage value of the applied voltage applied to the transparent electrode is configured to be controlled according to the wavelength range of the liquid crystal light passing through the liquid crystal layer and the transparent electrode, the number of pixels of the display image is apparent. It is possible to carry out the upper multiplication and to correct the positional deviation of the dots due to the difference in color of the display image.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing a configuration of a main part of an image display device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a pixel configuration of an image obtained by the image display device according to the first embodiment.

FIG. 3 is a sectional view according to a state of an optical path deflecting element according to a second embodiment of the present invention.

FIG. 4 is a graph showing a relationship between a pixel array in a liquid crystal cell of an optical path deflecting element according to a second embodiment of the present invention and a refractive index.

FIG. 5 is an explanatory diagram schematically showing an optical path when light emitted from four pixels of a liquid crystal light valve of an optical path deflecting element according to a second embodiment of the present invention enters a liquid crystal cell.

FIG. 6 is an explanatory view schematically showing the relationship between the wavelength of transmitted light and the deflection amount when the voltage applied to the transparent electrode of the optical path deflecting element according to the second embodiment of the present invention is not controlled. Is.

FIG. 7 is an explanatory diagram schematically showing the relationship between the wavelength of transmitted light and the deflection amount when the voltage applied to the transparent electrode of the optical path deflecting element according to the second embodiment of the present invention is controlled. Is.

FIG. 8 is an explanatory diagram schematically showing a correspondence relationship between pixels of an optical path deflecting element and pixels of a liquid crystal light valve according to a second embodiment of the present invention.

FIG. 9 is a cross-sectional view for each state showing a method for controlling the optical path deflecting element according to the second embodiment of the present invention and schematically showing a structure when a pixel reducing function is added.

FIG. 10 is a graph showing a relationship between a pixel array direction position in a liquid crystal cell and a refractive index when a pixel reducing function is added to the optical path deflecting element according to the second embodiment of the invention.

FIG. 11 is a schematic optical path in the case where light emitted from four pixels of a liquid crystal light valve enters a liquid crystal cell when a pixel reducing function is added to the optical path deflecting element according to the second embodiment of the present invention. FIG.

FIG. 12 is a wavelength and a deflection amount of transmitted light when correction control of a voltage applied to a transparent electrode is not performed when a pixel reducing function of the optical path deflecting element according to the second embodiment of the present invention is added. It is explanatory drawing which shows the relationship with.

FIG. 13 shows a control method of an optical path deflecting element according to a third embodiment of the present invention, in which a transmitted light in the case of performing a correction control of a voltage applied to a transparent electrode when a pixel reducing function is added. It is explanatory drawing which shows the relationship between a wavelength and the amount of deflection typically.

FIG. 14 is an explanatory diagram exemplifying, for each main component, a configuration of an image display device that employs a method for controlling an optical path deflecting element according to a third embodiment of the present invention.

FIG. 15 is a perspective view illustrating a main configuration of a field sequential image display device that employs a method of controlling an optical path deflecting element according to a third embodiment of the present invention.

FIG. 16 is a diagram illustrating a field-sequential image display device of the optical path deflecting element according to the first embodiment of the present invention, in which a wavelength of transmitted light and a deflection amount are obtained when correction control of a voltage applied to a transparent electrode is not performed. It is explanatory drawing which shows the relationship with.

FIG. 17 is another explanatory view schematically showing the relationship between the wavelength of transmitted light and the amount of deflection when the voltage applied to the transparent electrode is not corrected and controlled in the field-sequential image display device of the present invention. Is.

FIG. 18 is an explanatory diagram showing a method for correcting and controlling the voltage applied to the transparent electrode in the field-sequential image display device of the present invention.

FIG. 19 is an explanatory diagram schematically showing the relationship between the wavelength of transmitted light and the amount of deflection during the correction control of the voltage applied to the transparent electrode in the field-sequential image display device of the present invention. Is.

FIG. 20 is an explanatory diagram schematically showing the relationship between the wavelength of transmitted light and the amount of deflection when correction control of the voltage applied to the transparent electrode is performed in the field-sequential image display device of the present invention. .

FIG. 21 is an explanatory diagram showing a method of controlling an optical path deflecting element according to a fifth embodiment of the present invention and showing an arrangement of optical elements for correcting deflection of an optical path by a liquid crystal lens array formed by a liquid crystal layer.

FIG. 22 is a sectional view schematically showing a configuration of an optical path deflecting element according to a third embodiment of the present invention.

FIG. 23 is a sectional view schematically showing a configuration of an optical path deflecting element according to a fourth embodiment of the present invention.

[Explanation of symbols]

2a Actual pixel 2b Apparent pixel 51 Emitting side pixel 52 Outgoing light 53 Liquid crystal cell 54 incident light 55 Incident side pixel 56 Luminous flux collimator 57 Optical Path Deflection Unit 61 Image display device 62 Light source / illuminator 81 Optical path deflection element (liquid crystal) 82 Light valve 111 light source driving means 112 display driving means 113 Optical path deflection voltage control means 114 Image display control circuit 121 white lamp 122 Diffuser 123 Condenser lens 124 Transmissive liquid crystal light valve 125 Optical Path Deflection Element 126 Projection lens 127 screen 311 transparent substrate 312 Transparent electrode array 313 Liquid crystal layer 314 transparent electrode 315 transparent substrate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 21/00 G03B 21/00 E (72) Inventor Hiroyuki Sugimoto 1-3-6 Nakamagome, Ota-ku, Tokyo No. In stock company Ricoh (72) Inventor Ero Futamura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh stock company (72) Inventor Yumi Matsuki 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Yasuyuki Takiguchi 1-3-6 Nakamagome, Ota-ku, Tokyo F-Term (Reference) 2R088 EA13 EA15 EA45 HA01 HA02 HA06 HA24 HA28 JA09 MA03 MA05 2H091 FA26X FA26Z FA41Z FA50Z GA02 GA11 HA09 LA15 LA16 MA07 2H093 NA65 NC02 NC43 ND17 ND20 NE03 NE06 NF09 NG02 NG07

Claims (7)

[Claims] 1. An optical path deflecting element having a pair of transparent substrates, a liquid crystal layer between the pair of transparent substrates, and a transparent electrode for applying an electric field to the liquid crystal layer, in a wavelength range of incident light to the liquid crystal layer. Correspondingly, an optical path deflection element comprising optical path deflection voltage control means for applying different applied voltages to each of the plurality of transparent electrodes. 2. The optical path deflection voltage control means, when light of a plurality of different wavelength bands is incident on the optical path deflecting element while sequentially switching in time, sets the value of the applied voltage temporally corresponding to each wavelength band. The optical path deflecting element according to claim 1, wherein the optical path deflecting element is configured to be sequentially switched to. 3. A state in which a pair of transparent substrates, a liquid crystal layer between the pair of transparent electrodes, and a transparent electrode for applying an electric field to the liquid crystal layer are provided, and light in a plurality of different wavelength regions is spatially distributed. In the optical path deflecting element which is incident on the optical path deflecting element, a plurality of regions corresponding to respective wavelength ranges are formed, and the optical path deflecting element has condition setting means for setting different optical path deflecting conditions for each of the regions. 4. The optical path deflecting element according to claim 3, wherein the condition setting means has an optical path deflection voltage control means for setting a different applied voltage for each region. 5. An image display device in which a plurality of light-controllable pixels are two-dimensionally arranged according to at least image information, a light source for illuminating the image display device, and an image pattern displayed on the image display device. The optical member for observation and the optical path between the image display element and the optical member are deflected for each of a plurality of subfields obtained by temporally dividing the image field. By displaying an image pattern in which the display device is shifted according to the deflection of the optical path for each subfield, the apparent number of pixels of the image display element is increased and the display image is displayed. An image display device characterized in that it is configured to display by correcting the positional deviation of dots due to the color. 6. A light source or a wavelength switching means for irradiating the image display element while sequentially switching light of a plurality of different wavelength ranges in time, and the image display element is controlled by using an image signal corresponding to each wavelength. The image display device which obtains a color image by driving has optical path deflection voltage control means for changing the applied voltage of the optical path deflection element in synchronization with the switching timing of each wavelength. Image display device. 7. A method of controlling an optical path deflecting element comprising a pair of transparent substrates, a liquid crystal layer between the transparent substrates, and a transparent electrode for applying an electric field to the liquid crystal layer. A method of controlling an optical path deflecting element, wherein a voltage value is controlled in accordance with a wavelength range of liquid crystal light passing through the liquid crystal layer and the transparent electrode.