JPH0239018A - display device - Google Patents

Abstract

PURPOSE:To write and plot any information patterns of both of a diaphragm and an image to a liquid crystal element at high speed with a simple constitution by scanning the surface of the liquid crystal element with laser beam in a write optical system by means of a selective switching and write-processing the aimed display information pattern. CONSTITUTION:The surface of the liquid crystal element is scanned with the laser beam by the write optical system, and the aimed display information pattern is write-processed. In such a case, a rotary polyhedron mirror 13 is used both for a function as the mirror of one side of two galvanomirrors in a vector scanning mode and for a function as the original rotary polyhedron mirror in a raster scanning mode. Namely, by operating a device in selectively switching a control system to the control system to execute the write in the vector scanning mode when the display information pattern is the diaphragm and to the control system to execute the write in the raster scanning mode when the pattern is the image according to the mode of the aimed display information pattern to be written, the information patterns of both of the line picture and the image can be write and plotted at high speed in the satisfactory scanning modes, respectively.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a display device, more specifically, a liquid crystal element is used as an information display medium, and a target display information pattern is written by scanning the surface of the liquid crystal element with a laser beam. The present invention relates to a display device using a processing method.

(Prior Art) Figures 3 and 4 are schematic configuration diagrams of a specific example of the above-mentioned display device (monochrome type liquid crystal projection type enlarged display device). The apparatus is roughly divided into a writing optical system and a projection optical system (reading optical system), and FIG. 3 is a perspective view of the writing optical system A, and FIG. 4 is a schematic diagram of the configuration of the projection optical system B. .

In the figure, 6 is a liquid crystal element as an information display medium, and the one in this example is a thin plate-like element (6) using smectic liquid crystal.
size (for example, several centimeters square). A writing optical system A is located behind the liquid crystal element 6 on the back side of the element.
A projection optical system B is arranged on the surface side.

In the writing optical system A, a semiconductor laser (laser diode) 1 serves as a laser output means, and is driven by a control circuit (not shown) to output a laser beam 12 . The output laser beam is aligned by a collimator lens 2, subjected to beam direction control by an X-axis galvanometer mirror 3 and a Y-axis galvanometer mirror 4, and focused onto the back surface of a liquid crystal element 6 through a writing lens 5. The galvano mirrors 3 and 4 around the X-axis and Y-axis are controlled in reciprocating rotational direction and rotational angular velocity in accordance with the target display information pattern by drive devices 3a and 4a, respectively, which are controlled by an M control circuit (not shown). As a result, the back surface of the liquid crystal element 6 is subjected to vector scanning exposure by a laser beam corresponding to the intended display information pattern. That is, the liquid crystal element 6 is subjected to a writing process 12' corresponding to the target display information pattern using the laser beam 12 by the writing optical system A on the back side thereof.

In the liquid crystal element (this example is an element using smectic liquid crystal) 6, the liquid crystal in the area hit by the laser beam 12 becomes a liquid state due to beam irradiation and heating, and as it cools, the arrangement of molecules is disordered and light is scattered. The non-heated portion that is not hit by the laser beam is transparent, and in comparison with this non-written transparent portion, the portion that is hit by the laser beam and is in a light scattering state appears on the surface of the liquid crystal element 6 as a writing pattern.

In the projection optical system B (FIG. 4), 8 is a projection light source such as a xenon lamp, and the light from this light source is focused by a condenser lens 9 and reflected by a mirror 10 toward the surface of the liquid crystal element 6. , the entire surface of the liquid crystal element 6 is irradiated. Then, the reflected light of the liquid crystal element surface of the irradiated light is focused by the projection lenses 11 at a position avoiding the reflection mirror 10 of the irradiated light, and is then enlarged and imaged on the screen 7 surface.

That is, by performing the writing process 12' of the target display information pattern on the surface of the liquid crystal element 6 using the laser beam 12 by the writing optical system A as described above, the light-scattering writing pattern appearing on the surface of the liquid crystal element is projected onto the surface of the liquid crystal element 6. The image is enlarged and projected onto the screen 7 by the system B to be displayed.

FIG. 5 shows a cross-sectional model diagram of the reflective liquid crystal element 6. As shown in FIG.

6a is a glass substrate on the back side of the element, 6b is a Cr2O3 absorption film, 6C is an A2 reflection film, 6d is a smectic liquid crystal layer, 6e
is a transparent electrode, 6f is a glass substrate on the front side of the element, and 6g is A1
This is a power supply device that applies voltage between the reflective film and the transparent electrode 6e, and can be switched between high voltage and low voltage.

The state change of the liquid crystal 6d is as follows: Initially, when a high voltage is applied from the power supply device 6g to the area where a figure is written, the liquid crystal 6d becomes transparent, and the projected light is completely reflected by the AIL reflective film 6g and is not absorbed. Next, when graphic writing is started, the application of voltage by the power supply device 6g is interrupted. The area hit by the laser beam 12 turns into a liquid state due to heat, but when it cools down, it becomes a scattering state, and the projected light is scattered at that area, so that the inscribed area appears as a figure. If you want to partially erase the figure after writing it, you can make it into a liquid state by shining the laser beam 12 on that spot.
When a low voltage is applied there, it becomes transparent and the figure is erased.

(Problems to be Solved by the Invention) As in the above-mentioned display device, the laser beam scanning aging of the display information pattern on the liquid crystal element 6 is controlled by a vector using two galvano mirrors 3 and 4 on the X-axis circumference and the Y-axis circumference. For methods and configurations that are executed by scanning, the written and displayed information pattern is often composed of lines, such as in drawings,
So-called line drawings are advantageous because they can be written at high speed. However, in the case of a so-called image having a filled-in area, it takes time to draw, which is disadvantageous.

That is, with the display device described in F, it is somewhat difficult to efficiently draw both the line drawing information pattern and the drawing line information pattern. Also, from the viewpoint of maintenance and adjustment, it is desirable to have as few precision parts as possible, such as galvanometer mirrors, that require delicate A adjustment.

Images are written using raster scanning rather than vector scanning.

Scanning is much faster and more advantageous, but when performing raster scanning writing with a galvanometer mirror, only the X-axis mirror 3 performs reciprocating rotational movement, so in terms of operating time, the other Y-axis It is significantly longer than shaft mirror 4,
The durability of the drive system is a problem, and the speed is slow and inefficient.

In addition to the X-axis circumferential galvano mirror 3, a rotating polyhedral mirror (so-called polygon mirror) exclusively for raster scanning is installed, and when writing line drawings, vector scanning writing is performed using two galvano-mirrors for the X-axis circumference and Y-axis. At the time of writing, it is conceivable to change the X-axis circumferential galvano mirror 3 to a rotating polyhedral mirror to perform raster scanning writing, but this increases the number of parts and complicates control, which is uneconomical.

In view of the above, it is an object of the present invention to provide a display device of this type H, which is capable of writing and drawing information patterns of both line drawings and images on a liquid crystal element, which is an information display medium, at high speed with a rational and simple configuration. With the goal.

(Means for Solving the Problems) The present invention is a display device in which a target display information pattern is written by scanning the surface of a liquid crystal element as an information display medium with a laser beam using a writing optical system. The writing optical system includes one galvanometer mirror, a driving device thereof, a rotating polygonal mirror, and a stepping motor for driving the same, and controls the reciprocating rotational movement of the rotating polygonal mirror within a predetermined angular range. a control system that executes writing of a desired display information pattern by scanning a liquid crystal element surface with a laser beam in a vector scanning mode in cooperation with a mirror on an arbitrary surface and the galvanometer mirror driven by the drive device; , controlling the rotational movement of the rotating polygonal mirror in a predetermined direction, and scanning the liquid crystal element surface with a laser beam in a raster scanning mode in cooperation with the rotating polygonal mirror and a galvanometer mirror driven by the drive device; The present invention is a display device characterized by having a control system that executes writing of a target display information pattern.

(Function) 4.Depending on the aspect of the target display information pattern to be written, that is, when the display information pattern is a line drawing, the control system is configured to execute writing in vector scanning mode.
In addition, by selectively switching to a control system that executes writing in raster scanning mode for images and operating the device, information patterns for both line drawings and images can be written at high speed in the respective appropriate scanning modes. Drawing is executed.

The rotating polyhedral mirror functions as one of the two galvano mirrors in vector scanning mode and as the original rotating polyhedral mirror in raster scanning mode, so in the end only one galvano mirror is installed. This reduces the number of galvanometer mirrors, which are precision parts, and facilitates adjustment.

By using a polyhedral mirror, raster scanning, which is the original purpose, can be performed at high speed, so high definition images can be obtained in a short time.

(Example) Example 1 FIG. 1 is a perspective view showing the configuration of a writing optical system A of a display device according to an example. Although the projection optical system (B) is omitted from the figure, it has the same configuration as the projection optical system B (FIG. 4) of the apparatus of the aforementioned example. Also, in the writing optical system A of FIG. 1, the same reference numerals are given to the same components and parts as those of the optical system A (FIG. 3) of the above-mentioned example apparatus, and the explanation thereof will be omitted.

In FIG. 1, reference numeral 13 denotes a rotating polygon mirror, and this polygon mirror 13 is arranged in a replacement relationship with the X-axis circumferential galvanometer mirror 3 in the apparatus shown in FIG. 14 is a high-precision stepping motor for driving the polyhedral mirror 13, 15 is a control section for the motor, and 16 is a main control section.

The main body control unit 16 includes a vector scanning mode execution control system,
It includes an execution control system for the raster scanning mode, and switching between the two control systems can be performed by a scanning mode selection switching means 16a such as a manual knob or switch, or by an automatic switching signal from an automatic control system. It will be done.

When the target display information pattern is a line drawing, the mode is switched or automatically switched to the vector scanning mode, and when it is an image, the mode is switched or automatically switched to the raster scanning mode.

(2) Operation in vector scanning mode In this scanning mode, only arbitrary -.faces of the polyhedral mirror 13 are used. That is, the operation of the polyhedral mirror 13 is a reciprocating rotational movement within a predetermined range, similar to the galvanometer mirror 3 around the X-axis in the apparatus shown in FIG.

The movement is controlled by the stepping motor 14 from the main body control section 16.
It rotates in a predetermined direction by the number of clock pulses sent to the control unit 15 of the controller.

Controls such as directions of rotation, pulse count, start and stop of rotation, etc. are performed by a plurality of control signal lines 17 sent from the main body control section 16 to the Stellar Dong motor control section 15.

The stepping motor 14 needs to rotate smoothly,
A material with a large number of phases is desirable.

In order to make the polyhedral mirror 13 function as a carbanomirror around the X-axis, reciprocating rotational movement control within a predetermined angle range using only one arbitrary surface of the mirror, and control from the main body control unit 16 performed in conjunction with this, are performed. Control signal too
Combined with the reciprocating rotational movement control of the axial angle galvanometer mirror 4, the back surface of the liquid crystal element 6 is scanned with a laser beam in vector scanning mode, and a line drawing that is the desired display information pattern is written at high speed, and the written information is The pattern is enlarged and projected onto the screen surface by a projection optical system B (not shown).

■Operation in raster scanning mode In this case, the operation of the Y-axis angle galvanometer mirror 4 does not always repeat reciprocating rotation as in the case of vector scanning, but only by the width of one scan, for example, as shown in Figure 1. CC in
All you have to do is rotate it in the W direction. Then, one raster worth of digital information is sent out from the semiconductor laser 1 until the next rotation. This signal and operation is similar to one raster of a normal laser double printer. In the rotation of the polyhedral mirror 13, it is sufficient to continue rotating at a constant speed only in the CCW direction.

By combining the unidirectional constant speed rotation control of the polyhedral mirror 13 and the unidirectional rotation control of the Y-axis angle galvanometer mirror 4 by the width of one test, the back surface of the liquid crystal element 6 is scanned by the laser beam in raster scanning mode. The beam is scanned to write an image, which is a target display information pattern, at high speed, and the written information pattern is enlarged and projected onto the screen surface by a projection optical system.

Embodiment 2 In the apparatus of Embodiment 1 shown in FIG. 1, one high-precision stepping motor 14 is used as a driving means for the polygon mirror 13. However, since the polygon mirror 13 is required to rotate at a constant speed, it has low inertia. The load is often large and it takes time to stop. Therefore, if it is necessary to quickly switch from the raster scanning mode to the vector scanning mode, this stopping time is wasted, so a brake means is required.

In this embodiment, after the Stellar Dong motor 14 is stopped as the braking means, the main body control section 16 controls the motor control section 15.
The polyhedral mirror is controlled to rotate in the opposite direction (CW) to the rotation of the polyhedral mirror for a short period of time. It is desirable to do this multiple times in a short period of time to reduce the load on the motor side.

Embodiment 3 Embodiment 2 was characterized by adding a braking effect using the control method, but in this embodiment, in order to stop the motor more quickly, a braking device 18 is installed coaxially with the stepping motor 14 as shown in the second diagram. It is characterized by the addition of The brake device 18 includes a powder brake, an electromagnetic brake, an electromagnetic clutch, etc., and may be selected on a case-by-case basis.

The brake device 18 may be driven after the raster scanning mode ends and a stop signal for the stepping motor 14 is issued.

(Effects of the Invention) As described above, according to the present invention, a display device in which a target display information pattern is written by scanning the surface of a liquid crystal display element with a laser beam using a writing optical system can be realized in a reasonably simple manner. With this configuration, it is possible to select and execute laser scanning writing of display information patterns in vector scanning mode or raster scanning mode, and by switching the selection, it is possible to write and draw information patterns of both line drawings and images at high speed. , the intended purpose is well achieved and it is effectively suitable as an improvement to this type of display device.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic configuration of a writing optical system portion of a display device according to an embodiment, FIG. FIG. 3 is a perspective view showing a schematic configuration of a writing optical system portion of a conventional device, FIG. 4 is a schematic configuration diagram of a projection optical system portion, and FIG. 5 is a cross-sectional model diagram of a liquid crystal element. A is a writing optical system, B is a projection optical system, 1 is a semiconductor laser, 2 is a collimator lens, 3 and 4 are galvanometer mirrors for the X-axis and Y-axis, 55 is a writing lens, 6 is a liquid crystal element, 8
is a projection light source, 11 is a projection lens, 7 is a screen, 1
3 is a polyhedral mirror, and 14 is a stepping motor.

Claims (1)

[Claims] (1) A display device that writes a desired display information pattern by scanning the surface of a liquid crystal element as an information display medium with a laser beam using a writing optical system, and the writing optical system includes a single galvano mirror and , including a driving device thereof, a rotating polygonal mirror, and a stepping motor for driving the rotating polygonal mirror, and controls the reciprocating rotational movement of the rotating polygonal mirror within a predetermined angular range to drive an arbitrary one-sided mirror and the driving device. a control system that executes writing of a desired display information pattern by scanning a liquid crystal element surface with a laser beam in a vector scanning mode in cooperation with the galvanometer mirror driven by the rotary polyhedral mirror; The rotary polyhedral mirror and the galvanometer mirror driven by the drive device control the rotational movement to scan the liquid crystal element surface with a laser beam in a raster scanning mode to write a desired display information pattern. A display device comprising a control system.