JPS58182615A - Optical printer - Google Patents

Abstract

PURPOSE:To obtain an optical printer of simple constitution which has high resolution by setting the scanning-directional effective length of the optical shutter area of an optical shutter element less than minimum scanning-directional record length. CONSTITUTION:The optical shutter element 34 consists of electric ceramics 24, an electrode 25, two polarizing plates 26 and 27 having axes of polarization crossing with each other at right angles, and a light shielding plate 28 for limiting the length of the optical shutter area in the scanning direction F to width (b). The direction of light incidence is shown by D. Light from a light source 29 is passed through the optical shutter element 34 and focused on a photoreceptor moving in a direction G through an image-forming lens 36. For recording of minimum record length rm in the scanning direction, when b=rmin/m for the effective length bm of the optical shutter where (m) is the image-formation magnification of the image-forming lens, the photoreceptor 23 moves continuously, but the optical shutter 34 is operated in an extremely short time. When b<rm/m, it is unnecessary to operate the optical shutter in the short time. The printer has high resolution because no cylindrical lens is used.

Description

Detailed Description of the Invention The present invention uses an optical shutter element made of electro-optic ceramics or the like to arbitrarily transmit or block light from an exposure light source according to a recording signal, thereby recording light on a photoreceptor. This invention relates to an optical printer that performs.

Hereinafter, an example of the structure of what is known as an optical shutter element will first be explained with reference to FIG. FIG. 1 is a cross-sectional view of the optical shutter element taken along a plane parallel to the incident direction A of light, in which an electrode 2 for applying an electric field is provided on a transparent ceramic flat plate 1 such as PLZT. 0 shows a structure in which a substrate and the front and back sides of the main surface of the substrate through which light is transmitted are sandwiched between polarizing plates 3 and 4 having mutually orthogonal polarization axes.
FIG. 2 is a plan view showing an example of the electrode arrangement of the conventional optical shutter element shown in FIG. 1, and the incident direction of light is perpendicular to the paper plane. (hereinafter referred to as the scanning direction).In Fig. 2,
6 to 1o are strip electrodes, 11 is a strip electrode group, 12, 1
3.14 shows the optical shutter area.

Now, in FIG. 2, it is assumed that electrodes 6 and 7 are grounded and a potential is applied to electrode 8. At this time, since no electric field is applied to 12 parts of the optical shutter region, the incident light is blocked by the two polarizing plates. On the other hand, 13 in the optical shutter area
Since an electric field is applied to the part, the incident light is transmitted through the action of the electro-optic ceramic.

Conventionally, as a printer using an optical shutter element having the above-described structure, there is an example of a configuration as shown in FIG. That is, the light emitted from the light source 16 is converted into parallel light by the collimating reflector 16 and the collimating lens 17, and then the shutter element 2
1, the transmitted light is apertured by a cylindrical lens 22, and optical recording is performed while moving the photoreceptor 23 in the C direction.

Note that the optical shutter element 21. , is composed of an electro-optic ceramic substrate 18 having electrodes on its surface, and two polarizing plates 19 and 20 having mutually orthogonal polarization axes.

Since the lintrical lens has the ability to form images in only one direction (two directions in Figure 3),
In order to reduce diffraction in the y-direction (in the figure) and ensure resolution, the light source must be extremely accurately parallel light, which makes the collimating optical system complex and extremely difficult to adjust. there were.

The present invention eliminates the above-mentioned conventional drawbacks and has a simple structure and high performance by making the length in the scanning direction of the optical shutter area of the optical shutter element equal to or less than the length corresponding to the minimum recording length in the scanning direction. The present invention provides an optical printer having high resolution.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 4 is a perspective view showing an example of the structure of the optical shutter element used in the present invention (however, it is shown with a stepped cutout). In FIG. 4, 24 is an electro-optic ceramic, 25 is an electrode for applying an electric field to the electro-optic ceramic, 26 and 27 are two polarizing plates having polarization axes perpendicular to each other, and 28 is an optical 7-yano polarizer. A light-shielding plate is shown for limiting the length of the area in the scanning direction to the width indicated by the symbol in the figure, where D indicates the direction of light incidence and F indicates the scanning direction.

Note that 24 to 27 in FIG. 4 correspond to 1 to 4 in FIG. 1, respectively, and the corresponding ones have similar functions.

FIG. 5 shows the configuration of an embodiment of an optical printer of the present invention using the optical shutter element shown in FIG. 4. In FIG. 5, 29 is a light source, 3o is an electro-optic ceramic substrate with electrodes on its surface, 31.32 is two polarizing plates having mutually orthogonal polarization axes, 33 is a light shielding plate, and 34
30 to 32 represent a light shutter element, 3!5 represents an imaging lens, and 36 represents a photoreceptor. Note that the photoreceptor moves in the C direction, and the basic operation is the same as that of the optical printer shown in FIG.

In the following explanation of optical recording in the optical printer having the above configuration, the imaging magnification by the imaging lens 36 is assumed to be m, and the symbol "A" in FIG. 4 is used.

The first method is to fix b=□ and move the photoreceptor intermittently. That is, optical recording is performed with the photoconductor stationary, and when recording is completed at that photoconductor position,
In this method, the photoreceptor is moved to the next recording position and recording is performed sequentially.

The second method, also referred to as ``b-□'', is a method in which the photoreceptor is moved continuously. However, in this case, the optical shutter is operated only for a very short time. Otherwise, since the photoreceptor is continuously moving, the actual minimum recording length in the scanning direction will be longer than rmin.

The third method is to use brmin and move the photoreceptor continuously. In this case, since brmin is used, it is not necessary to operate the optical shutter element for an extremely short period of time as in the second method.

The fourth method is to move b(□, i.e., b very small compared to r IQ i n -1,-, and to move the photoreceptor continuously. In this case, the photoreceptor moves in the scanning direction of the optical recording. The optical shutter element is operated only while moving by the R short recording length.

As mentioned above, the four methods have been described, but in any of the methods, b≦−part, that is, the length of the substantial light shunter area of the light shunter element in the scanning direction is the minimum length of the optical recording in the scanning direction. There is no change in the fact that the length is less than the length corresponding to the recording length.

As is clear from the above description, the present invention makes the length of the substantial optical shutter area of the optical shunter element in the scanning direction less than or equal to the minimum recording length in the scanning direction. It is an object of the present invention to provide an optical printer with a simple configuration and high resolution.According to the present invention, since the configuration is extremely simple, the cost of the optical printer can be significantly reduced and the reliability can be improved. Since it can be realized, it has great practical value.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the general structure of an optical shutter element.
FIG. 2 is a plan view showing an example of the electrode arrangement of a conventional optical shutter element, FIG. 3 is a perspective view showing an example of the configuration of a conventional optical printer, and FIG. 4 is a configuration of the optical shutter element used in the present invention. FIG. 6 is a partially cutaway perspective view showing one example. FIG. 6 is a perspective view showing the configuration of an embodiment of the optical printer of the present invention.・ 24... Electro-optic transparent ceramic flat plate, 25.
... Electrode, 26, 27, 31.3'2...
...Polarizing plate, 28.33... Light shielding plate, 29...
...Light source, 3o... Electro-optic transparent ceramic substrate having electrodes on the surface, 34... Light shutter element, 36... Imaging lens, 36...・
...Photoreceptor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 1 Figure 3 Figure 4 Figure 2 Figure 5

Claims (2)

[Claims] (1) At least a light source, a photoconductor, and a light shutter element disposed between the light source and the photoconductor and having a light transmittance that changes depending on an applied electric field, the shutter being arranged between the photoconductor and the shutter. The optical shutter element is configured to perform optical recording on the photoreceptor while moving relative to the photoreceptor, and the length of the substantial optical shutter area of the optical shutter element in the direction of the relative movement is determined by the optical recording. An optical printer characterized in that the length is equal to or less than the minimum recording length in the direction of the relative movement of the optical printer. (2) By providing a light shielding plate on the light shutter element that limits the length of the light beam emitted from the light source in the direction of the relative motion, the length of the relative motion of the substantial light shutter area of the light shutter element can be limited. 2. The optical printer according to claim 1, wherein the length is less than or equal to the minimum recording length in the direction of the relative movement of optical recording.