JPS60262126A - Optical shutter element - Google Patents

Abstract

PURPOSE:To decrease the change in the light transmissivity of an optical shutter element with a change in ambient temp. by forming plural thin conductive film pieces on a plate-shaped light transmittable ceramics in a manner that the film pieces do not contact with each other and providing electrodes thereon. CONSTITUTION:The plural thin transparent conductor film pieces 12 are formed on at least one surface of the plate-shaped light transmittable ceramics 11 consisting of PLZT (lead titanate zirconate added with La) having an electrooptic effect and photoelastic effect in a manner that the thin film pieces do not contact with each other and the electrodes 13 are provided thereon so as to form the optical shutter. An electric field is liable to concentate around the transparent pieces 12 and the transmissivity of the optical shutter part is different according to places when the voltage is impressed between the electrodes 13 and therefore the change in the light transmissivity over the entire part of the optical shutter part with temp. decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a writing device for an optical printer;
The present invention relates to a solid-state optical shutter element that can be used in optical control devices such as high-speed optical shutters in cameras.

Conventional configurations and their problems In recent years, the development of optical-related technologies such as optical communication and optical information processing has been very active, and as a result, optical components,
The development of optical control devices is gaining importance. Among these, solid translucent porcelain having an electro-optic effect and a photoelastic effect can also be used as a light controller as a light control device, and is expected to have various applications.

Currently, what is known as the above-mentioned optical shutter element is lead zirconate titanate (P L Z T
), etc., on a flat plate of translucent porcelain, with −450° or more of electrodes provided symmetrically on the front and back sides, or at least on one side, with respect to the direction of the electric field vector generated when a voltage is applied to the electrodes. It has a structure in which it is sandwiched between polarizing plates having a polarization axis of . Hereinafter, a conventional optical shutter element will be explained with reference to the drawings.

Figure 1 shows the configuration of a conventional optical shutter element, in which 1 is a PLZT flat plate, 2 is an electrode formed on the PLZT flat plate 1, 3 is a polarizer, and 4 is an analyzer. , the polarization axes are arranged to be orthogonal to each other in a direction of ±45° with respect to the direction of an electric field vector generated when a voltage is applied between the electrodes 2. The operation of the optical shutter element configured in this way will be explained below.

When light is irradiated from the rear of the polarizer in Figure 1, 3, the PLZ
When no voltage is applied between the electrodes 2 formed on the T flat plate 1, birefringence due to the electro-optic effect and photoelastic effect does not occur, and the polarizer 3. The light is blocked by the analyzer 4, but when a voltage is applied between the electrodes 2, birefringence occurs due to the electro-optic effect and photoelastic effect, and the polarization state of the light changes.
Light passes through. Therefore, by applying or not applying a voltage between the electrodes 2, the intensity of light can be modulated, and the device can be expected to be used as a light control element.

However, PLZT electro-optic material not only has a strong Kerr effect as an electro-optic effect, but also has a large photoelastic effect in which when a voltage is applied, it produces strain proportional to the square of the electric field and causes birefringence. This effect is due to the large variation in characteristics due to temperature changes.
When the voltage for driving the light shutter element is kept constant, there is a problem in that the transmittance of a portion of the light shutter changes greatly in response to changes in ambient temperature.

OBJECTS OF THE INVENTION An object of the present invention is to provide a stable optical shutter element that is very effective for use as a light control device in optical printers and the like, and whose light transmittance changes very little in response to changes in ambient temperature.

Structure of the Invention The optical shutter element of the present invention has a plurality of transparent conductive thin film pieces arranged on at least one surface of a solid plate-like translucent porcelain having an electro-optic effect and a photoelastic effect. electrodes are provided thereon to form a light shutter, and polarizing plates are arranged on the front and back sides of the plate-shaped translucent porcelain so that the polarization axes make an angle of [900] with respect to each other. This reduces the change in light transmittance of the light shutter element due to temperature changes, resulting in a light shutter element that can provide a very stable output under actual usage environments. It is something.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a configuration diagram of an optical shutter element in an embodiment of the present invention.

In Fig. 2, 11 is a PLZT flat plate, and 12 is a PLZT plate.
Transparent conductive thin film piece formed on a flat plate, 13ba, PLZ
The electrodes 14 and 15, which are formed on the T-plate and which control the optical shutter operation, represent a polarizer and an analyzer, respectively. On the other hand, the polarization axes are configured to be orthogonal to each other in the directions of ±450.

The operating mechanism of the optical shutter element of this embodiment configured as described above will be explained below.

The principle of the optical shutter element having the structure according to the present invention is the same as that of the optical shutter element having the conventional structure, and when light is irradiated from the rear of the polarizer shown in FIG. When no voltage is applied between the electrodes 13, birefringence does not occur and light is blocked, but when a voltage is applied between the electrodes 13, the polarization state of the light changes and the light is transmitted. Become. However, in the case of the embodiment according to the present invention, as is clear from FIG. When a voltage is applied, the electric field tends to concentrate around the transparent conductive thin film piece, and the electric field strength applied to the PLZT flat plate 11 varies depending on the location. In other words, the transmittance of a portion of the light shutter differs depending on the location. Therefore, by controlling the voltage applied between the electrodes 13, in a part of the optical shutter where the electric field becomes thick, a half-wave electric field (the electric field required when the transmittance is maximum) is applied at room temperature. A larger electric field is applied than that, and the half-length electric field is not reached in the portion where the electric field becomes smaller.

In the P L Z Tl material, the half-wavelength electric field increases significantly as the temperature rises, so in the configuration of a conventional optical Yatta element, the transmittance of the light/Yatta portion changes considerably. However, in the configuration of the optical shutter element according to the present invention, when the temperature rises from room temperature, the half-wavelength electric field of the PLZT substrate increases, so the transmittance increases in the areas where the electric field is concentrated and large. In areas where the electric field is less concentrated, the transmittance decreases. Therefore, the transmittance of a light shutter element is measured as the average transmittance of each part, so although the transmittance distribution in each part of the light shutter changes, the transmittance of the entire aperture changes with temperature. can be reduced.

'1・□' In this example, the thickness is 40o (77
Using a PLZT flat plate of 1 m), an ITO transparent electrode was deposited on one side to a thickness of about 1000 (8 m), and a pattern of 5 (1 m) square thin film pieces was formed using photolithography technology. The area ratio of the thin film piece is PLZT
It was formed uniformly at a ratio of about 16:1 to the flat plate. On top of that, an Or-Au electrode was formed by photolithography technique. At this time, the thickness of the Or-Au electrode was about 6000 (8). In addition, the electrode width of the above electrode is 80 (lzm)
, with an electrode spacing of 150 (tt m ).

FIG. 3 shows the relationship between the transmittance of the optical shutter element and temperature in the configuration of the optical shutter element in this embodiment, and the relationship between the transmittance and temperature of the optical shutter element in the conventional configuration. In FIG. 3, the solid line represents the relationship between temperature and transmittance in the conventional configuration, and the broken line represents the relationship between temperature and transmittance in the configuration of the embodiment according to the present invention.

The applied voltage is 2oQ(v) in both cases. As is clear from the figure, the optical shutter element having the structure according to the present invention exhibited very stable transmittance in the actual operating temperature range of 20°C to 60''C.

In this embodiment, the transparent conductor thin film piece is made into a square with 6 (μm) sides, but the shape is not limited. However, regarding the size, if one of the transparent conductor thin film pieces becomes large, the unevenness of the transmittance of the light shutter aperture becomes large, and this does not become a problem in a light shutter element with a very large aperture, but for example, In an optical shutter element having a structure in which the optical shutter openings are small and are arranged in an array, unevenness in transmittance is not preferable because it causes variations in the optical shutter openings. With the configuration of this example, when the size of the conductor thin film piece is changed, the part of the optical shutter is 100 (p m ) x 100 (l1 m
), and as a result of measuring by changing the location of part of the light shutter, it was found that the conductor thin film piece had a corner reduction of 15 (μm) with respect to the distance between the electrodes of 15o (μm). In that case, the unevenness has almost disappeared. Furthermore, in this example, the area ratio of the conductor thin film piece to the light shutter opening was 1/16 to the area of the entire part of the light shunter, but measurements were performed with the above area ratio changed. result,
Between 1150 and 1/10, the transmittance change due to temperature change is within 1% in the temperature range of 20 to 60"C,
Good results were obtained.

In addition, in the examples related to the present invention, C was used as the electrode material.
Although r-Au was used, it is easy to imagine that similar results could be obtained with other electrode materials.

Further, the electrode shape is not limited to the interdigital electrode shape as in this example, and it can be easily assumed that similar results can be obtained with other electrode structures.

Effects of the Invention As is clear from the above description, the present invention has a plurality of transparent conductor thin film pieces mutually disposed on at least one surface of a solid plate-like translucent porcelain having an electro-optic effect and a photoelastic effect. The thin film pieces are formed so that they do not contact each other, and electrodes are provided thereon to form a light shutter, and polarizing plates are placed on the front and back sides of the plate-shaped translucent porcelain so that their polarization axes make an angle of 9o0 with each other. This structure reduces the change in the light transmittance of the light shunter element due to temperature changes, and provides light output that is extremely stable under actual usage environments. The present invention provides a shutter element.

The above is an example of the application of PLZT elements to the writing heads of optical printers and other applied devices in optical control devices and optical information processing technologies, which are attracting increasing attention for development in the future. It has a great effect on this.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional optical shutter element, FIG. 2 is a block diagram of an optical shutter element according to an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional optical shutter element, FIG. 2 is a diagram showing the relationship between temperature and transmittance of an optical Nyatter element configured as an example of the present invention. , 1 '1-゛-゛゛''"F&, 12-=! -”1
μ piece, 13... Optical shutter control electrode, 14
...Polarizer, 16...Analyzer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 5-14 (Figure 3 50 Temperature ('C) -

Claims (3)

[Claims] (1) A plurality of transparent conductive thin film pieces are formed on at least one surface of a solid plate-like translucent porcelain having an electro-optical effect and a photoelastic effect, so that the thin film pieces do not come into contact with each other, It has a structure in which electrodes are provided thereon to form a light shutter, and polarizing plates are arranged on the front and back sides of the plate-shaped translucent porcelain so that their polarization axes make an angle of 90° to each other. Optical shutter element. (2) The optical shutter element according to claim 1, wherein the longest dimension of the transparent conductor thin film piece is one-tenth or less of the distance between the electrodes. (3) The total area ratio of the transparent conductor thin film piece is 1/6 to 1/6 of the area of the entire opening of the optical shutter element.
The optical shirt-tar element according to claim 1, characterized in that the size is 1/10.