JPH04172391A - Image display device - Google Patents

Abstract

PURPOSE:To make the accurate display of an image possible by using emitting means arranged closely in the straight line as a writing light source for a space light modulation element. CONSTITUTION:Writing light 107 including the information of an image signal forms an image on a photoconduction layer 401 through a recording head, but in a part exposed to the writing light 107, the impedance of the photoconduction layer 401 lowers according to photointensity, and voltage between transference electrodes 402, 406 is mostly applied to a liquid crystal 405. When read light 111' deflected from a regenerating photosystem makes incidence in this state, the polarized state of the read light is modulated according to an electric field applied to the liquid crystal 405. Image is thereby regenerated on a polarizing plate 112 put on the side of the read light, and a human being can observe the displayed image. Thus the thin type precise image display can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image display device that displays two-dimensional images, and particularly to a thin, high-definition image display device that displays characters, graphics, and the like.

[Prior Art] As a conventional image display device, there is an image display device using a one-dimensionally arranged LED array and a galvanometer mirror as shown in FIG. 4 (for example, Pr.

C e e di in g so f S I
D, V o 1. 23°No, 3.
p p, 197-202. 1982).

Furthermore, projection type image display devices using spatial light modulation elements have also been developed (for example, 5PIE vol.

684 pp96-100.1986), one uses a single laser beam as a writing light source and scans it in the horizontal and vertical directions, and the other uses a CRT writing type.

[Problems to be Solved by the Invention] However, with the conventional techniques, it has not been possible to realize a compact and high-definition image display device.

An image display device using an LED array and a galvano mirror has high definition, but has the following problems.

(2) In order to scan the light from the LED array with a galvanometer mirror and display an image, a distance from the LED array to the light source is required, which makes miniaturization difficult.

(2) As the scanning angle of the galvano mirror increases, the displayed image will also become larger, but at the same time, the distortion will also increase. The scan angle is at the limit of about 30 degrees, which can be corrected optically and circuitically. In order to display a large image with a small scan angle, it is necessary to further increase the distance from the LED array to the light source, which goes against miniaturization.

(2) Although the light from the LED array is directly observed with the eyes, it can only be used in a dark environment where the galvanometer mirror and surroundings cannot be seen.

Therefore, in order to observe images in a bright environment, it is necessary to increase the depth.

Furthermore, the laser writing type using a spatial light modulation element has many movable parts and requires scanning in two horizontal and vertical axes, making it even more difficult to reduce the size and thickness. The CRT writing type has problems in that it is difficult to miniaturize due to the size of the CRT, requires installation adjustment and convergence adjustment, and is influenced by geomagnetism.

The present invention has been made to solve these problems, and its purpose is to provide a thin and high-definition image display device.

[Means for Solving the Problems] The image display device of the present invention has a writing layer made of a photoconductor whose conductivity changes depending on the amount of incident light, and a reading layer made of an electro-optic material whose refractive index changes depending on the electric field intensity. a spatial light modulator, a light-emitting means configured by linearly arranging a plurality of light-emitting bodies as a writing light source for the spatial light modulator, and a light-emitting body for driving the light-emitting bodies constituting the light-emitting means. a driving means, an image signal processing means for storing image data to be sent to the light emitter driving means in an image memory, and a focusing means for focusing radiation light emitted from the light emitting means on a writing layer on the spatial light modulation element. an image optical means, a means for linearly moving the light emitting means and the image forming optical means in a direction perpendicular to the arrangement direction and the emission direction of the light emitters, and a reading layer for reading out the image written on the spatial light modulation element. It is characterized by comprising a reproducing optical means for reproducing from.

[Example] The present invention will be explained in detail below based on the drawings.

FIG. 1 is a diagram showing an embodiment of an image display device of the present invention. The image signal 100 in the figure is a signal containing image information sent through an external memory or a transmission line, and may be code data indicating characters to be displayed, their font, and size.
It may also be a video signal.

In the case of video signals, an A/D converter is required to convert analog signals to digital signals.

The image signal processing means 101 processes the input image signal 100.
The data is expanded into bitmap data for input into the next image memory 102. FIG. 2 is an example of bitmap data of a binary image stored in the image memory in the image signal processing means 101. In this case, the image memory has a memory capacity of 17 rows and 14 columns, and data is stored in each address. are doing. The present invention is an image display device that displays the bitmap data shown in FIG. 2 for human observation. In FIG. 1, reference numeral 103 indicates an LED array which is a writing light source for sequentially recording one row of images on the writing layer of the spatial light modulation element 104. The LED array 103 has light emitting parts arranged in a direction perpendicular to the plane of the paper, and is shown as 103' in FIG. 3 when viewed from the light emitting surface side of the LED array 103. Here, there are 14 light emitting parts, corresponding to the number of pixels in one row in FIG. 105 in FIG.
A self-focus lens array (hereinafter abbreviated as SLA) shown in FIG. 1 is arranged to focus writing light from the LED array 103 on the writing layer of the spatial light modulation element 104 as an erect equal-magnification image. The LED array and SLA are integrated and will hereinafter be collectively referred to as a recording head. The recording head is moved by a linear motor 106, and writing light 107 from the recording head scans the writing layer of the spatial light modulation element.

In order to display the image signal converted into bitmap data as shown in FIG. 2, the recording head is first moved from a starting point at a constant speed using the linear motor 106. The first row of data from the image memory is shown in Figure 3.
After being transferred to the shift register 301 of the ED array drive circuit and latched, the recording head moves to the position of the first row, causing each LED to emit light using the driver array 303 and recording on the writing layer of the spatial light modulation element 104.

The data for the second row starts to be transferred after the first row is latched, and when the recording of the first row is completed and the recording head reaches the position of the second row, the LED array is made to emit light. In this way, all image data is recorded on the writing layer of the spatial light modulator. Shift register 30 configuring the LED drive circuit
1. Circuits such as the latch circuit 302 and the driver array 303 are arranged on the same ceramic substrate as the LED array 103 and connected using wire bonding. Furthermore, the effective speed of data transfer to the shift register can be increased by dividing one row into multiple pieces of data and transferring them. The position of the recording head is detected using a position sensor 108. The linear motor drive circuit 113, the LED array drive circuit 114, and the image memory 102 are controlled by a system control circuit 109 that generates each control signal from the position sensor 108 and the image signal 100. In the present invention, since the recording head can be moved at a constant speed, image distortion does not occur, and since there is no need to adjust the light emission time depending on the position, control of each part becomes very easy.

Here, image reproduction will be explained using the cross-sectional view of the spatial light modulator shown in FIG. The spatial light modulation element records a two-dimensional image on an electro-optic layer such as liquid crystal via a photoconductive layer 401 such as amorphous silicon or CdS.

Here, liquid crystal 405 is used as the electro-optic layer. The writing light 107 containing the information of the image signal is imaged on the photoconductive layer 401 by the recording head described above, but the impedance of the photoconductive layer 401 changes depending on the light intensity in the area where the writing light 107 is applied. Lowered transparent electrode 402.40
Most of the voltage between 6 and 6 is applied to liquid crystal 405. In this state, when the polarized readout light 111' from the reproduction optical system is incident, the polarization state of the readout light is modulated according to the electric field applied to the liquid crystal 405. Therefore, by placing the polarizing plate 112 on the readout side, the image is reproduced and the displayed image can be observed by humans. In addition, the liquid crystal 405 of the spatial light modulation element
In the case of a polymer-dispersed liquid crystal that utilizes light transmission and scattering, the polarizing plate 112 is not necessary.

Furthermore, if a liquid crystal with a memory function is used, the recording head only needs to be operated when a new image signal is input, thereby reducing power consumption. The light shielding layer 403 prevents the readout light 111' from entering the photoconductive layer.
The reflective layer 404 is provided to reflect read light.

In place of the LED array in FIG. 1, a plasma, a semiconductor laser, a liquid crystal shutter operating as a light shutter, or the like may be used as the light emitting means.

The linear density of the LED array can already be 15 dots/mm or more, and a resolution of 640 lines can be achieved at about 45 mm.

Further, in order to move the recording head in a straight line, a voice coil motor or a stepping motor may be used as the linear motor.

[Effects of the Invention] As described above, according to the present invention, since the light emitting means arranged in a straight line at high density are used as the writing light source of the spatial light modulation element, high-definition display can be performed.

In addition, since the number of light emitting elements is only the number of pixels for a certain scan line, the yield is significantly improved compared to an image display device in which light emitting elements are arranged in a matrix. Furthermore, since the recording head operates at a constant speed using a linear motor, there is no image distortion and there is no need to correct the amount of writing light, making control easier. Therefore, the depth becomes very thin. Furthermore, since a spatial light modulation element is used, images can be displayed with high contrast even in bright environments.

By combining the image display device of the present invention having the above-described effects with an external memory such as an optical disk or a semiconductor memory, a high-definition thin electronic book that is convenient to carry can be realized.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an image display device according to the present invention. FIG. 2 is a diagram showing data in an image memory for explaining the present invention in detail. FIG. 3 is a diagram showing an LED array driving section of the image display device of the present invention. FIG. 4 is a configuration diagram of a spatial light modulation element used in the present invention. 100... Image signal 101... Image signal processing means 102... Image memory 103... LED array 104... Spatial light modulation element 105... Self-focus lens 106... Linear motor 107... -Writing light 108...Position sensor 109...System control circuit 112...Polarizing plate 113...Linear motor drive circuit 114...LED array drive circuit 301...Shift register 302...Latch circuit 303...Goliper array and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki (@1 person) abcdefg
hij klmn -Figure 2 11O゛Figure 3

Claims (1)

[Scope of Claims] (a) A spatial light modulator whose writing layer is a photoconductor whose conductivity changes depending on the amount of incident light, and whose readout layer is an electro-optic material whose refractive index changes depending on the intensity of the electric field; (b) a light emitting means configured by linearly arranging a plurality of light emitting bodies as a writing light source for the spatial light modulator; (c) a light emitting body driving means for driving the light emitting bodies constituting the light emitting means; (d) image signal processing means for storing image data to be sent to the light emitter driving means in an image memory; and (e) image-forming of radiation light emitted from the light emitting means onto a writing layer on the spatial light modulation element. (f) means for linearly moving the light emitting means and the imaging optical means in a direction perpendicular to the arrangement direction and the emission direction of the light emitters; (g) the spatial light modulation element; 1. An image display device comprising a reproducing optical means for reproducing an image written on the readout layer from the readout layer.