JPS59616A - Photoelectric converter - Google Patents

Abstract

PURPOSE:To facilitate fine adjustment control over the quantity of light and adjusting operation, by providing an optical control plate made of liquid-crystal cells capable of controlling the quantity of light to photodetector in an optical path. CONSTITUTION:Light from a light source 5 is collimated by a collimator lens 6 to be made incident to the photodetector 7 through a moving scale 2 and a fixed scale 3, but the optical control plate 10 consisting of the liquid-crystal cells is arranged in the optical path and divided into four segments 10a-10d corresponding to the four photodetecting elements 7a-7d. Voltages impressed to the optical control plate 10 are controlled respectively to equalize the quantities of transmitted light to the photodetecting elements 7a-7d easily when light parts of the moving scale 2 and fixed scale 3 are superposed upon each other. Consequently, the adjusting operation is facilitated and a readjustment is made possible to improve the reliability greatly.

Description

Detailed Description of the Invention This invention is used in digital measuring instruments such as digital dial gauges, digital micrometers, digital hide gauges, and digital scales, and is used to photoelectrically convert and electrically detect the amount of movement of a moving object. The present invention relates to an improvement of a photoelectric conversion device.

A conventional example of this type of device will be described below.

FIG. 1 is an exploded perspective view of a conventional photoelectric conversion device.

In Fig. 1, reference numeral 1 is a moving scale made of a transparent member such as glass or plastic, and on its surface there is a well-known pattern 2 that is bright and dark against light at regular intervals at a constant pitch P. is being carried out. In addition, in the figure, the pitch P of pattern 2 is exaggerated. Roha glass,
This is a fixed scale made of a transparent material such as plastic, and one surface of the scale (like the moving scale 1,
A plurality of patterns 4 (in the figure, four patterns 74a, 4b, 4c,
4d is shown) is applied AC. In addition, in the figure, the pitch P of the pattern 4 is exaggerated.

Then, a plurality of patterns 4a, 4b, 4c,
For example, if 4d is 00 at turn 4a, pattern 41) is 90°, bump 4c is 180', pattern 4d &:! The phases are shifted from each other so that the angle becomes 270'. Reference numeral 5 indicates a light source such as a tungsten lamp or a light emitting diode, and 6 indicates a collimating lens, which converts the light emitted from the light source 5 into a parallel beam of light and transmits it to the mobile school 1 and beyond. 7 is a light receiving element provided on the substrate 8 corresponding to each of the plurality of patterns 4 formed on the fixed scale 3; in this example, the patterns 4a, 4
b, 4c, 4d, light receiving elements 7a, 71), 7
There are four, c and 7d. In such a configuration, when the light source 5 is made to emit light, the NRC light emitted from the light source 5 and irradiated onto the collimating lens B is collimated into a parallel beam by the collimating lens B and reaches the moving school 1.

After reaching moving scale 1, according to the bright/dark pattern 2.4 applied to moving scale 1 and fixed scale 2, when the bright parts of both scales that the light passes through overlap, the light receiving element 7 The amount of light received is maximum, and the pitch P is 1 from that point.
Since the amount of light becomes the minimum when the scale moves by /2, the amount of light changes approximately in the form of a triangular wave with respect to the amount of relative movement of both scales 2.4. Therefore, in this example, the light-receiving elements 7a, 7b, 7c, and 7d obtain four electrical signals in the form of a triangular wave, each having a phase difference lL of 90 degrees.

After the optical signal is converted into a drowsiness signal by the light-receiving elements (7a, 7b, 7c, 7d), four light-receiving elements (7a, 7b, 7c) are converted into a drowsiness signal within a counter as is well known, although not shown.

7d) After performing electrical processing to divide the four electrical signals with a 90° phase shift, they are converted into counting pulses, and the amount of movement is determined by matching the amount of movement of moving school 1 with the number of pulses. can be displayed digitally on the display unit.

By the way, there is a process of photoelectrically converting the light signal from the light source 5 into an electric signal by the light receiving elements 7a, 71), 7c, and 7d on both the moving scale 1 and the fixed school 20 scales. In this case, each of the light receiving elements 7a, 7b, 7c, and 7d is arranged according to the mutual positional relationship of the anti-sulcollimating lens 6, the movable scale 1, the fixed school 2, and the light receiving element 7, such as right angles and symmetry along the optical axis. There is often a difference in the amount of light received by the
When this amount of light varies, the amplitude of the almost triangular electrical signal obtained by each light receiving element will vary, causing problems in later electrical processing, especially in the generation of counting pulses. . Therefore, in the conventional device, as shown in FIG. 1, between the light source 5, the collimating lens 6 in the optical path of the light receiving element 7, and the movable school 1, the total light amount corresponding to each of the light receiving elements 7a, 7b, 7c, and 7d is Adjustment screws 9a, 91), 9c, and 9d are provided for adjustment, and by moving these four adjustment screws 9a, 9b, 9c, and 9d in and out as appropriate, the light passing through the collimating lens 6 can be adjusted. The total amount of light is controlled and adjusted, and the four light receiving elements 7a, 7b, 7c,
The amount of light directed to 7d is made uniform. However, in the conventional device that controls and adjusts the light intensity by moving the adjustment screw 9 in and out, C has to reduce the screw diameter and narrow the pitch of the screw when making fine adjustments.
However, there are limits to the thread diameter and thread pitch in terms of processing and mounting, and since the mounting positions of the screws 9 are located opposite to each other, adjustment work is troublesome.

Furthermore, after adjustment, the adjustment screw 9 is generally firmly fixed with adhesive to prevent it from moving, so it becomes impossible to adjust the adjustment screw 9 again when disassembling or repairing the device. Furthermore, due to the desire to downsize the device and shorten the optical path to reduce current consumption, when the adjustment screw 9 is installed close to the collimating lens 6, it is necessary to turn the adjustment screw 9 in turn. If it is too close, it may come into contact with the collimating lens 6 and cause scratches on the lens 6, resulting in C-stripes.

The present invention has been made in view of the above-mentioned point 1C, and by making it possible to adjust the amount of light to the light receiving element using a light control plate made of a liquid crystal cell instead of an adjustment screw, fine adjustment control of the amount of light, The purpose is to facilitate adjustment work, enable readjustment operations, and further improve reliability, thereby providing a complete photoelectric conversion device.

The gist of the kth aspect of the present invention that achieves the above object is as set forth in the claims above.

Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings below the star in FIG.

Incidentally, the same parts as in FIG. 1 are given the same reference numerals, and the description thereof will be omitted.

FIG. 2 is an exploded perspective view of the photoelectric conversion device of the present invention, in which 1 is a moving scale equipped with a pattern 2, 3 is a moving scale with a plurality of patterns 4
(Four patterns 4a, 41 in the figure), 4c.

71d) is provided with a fixed scale, 5 is a light source, 6 is a collimating lens, 7 is provided on a substrate 8; l'L/): Light receiving element, fixed school 3 patterns 4a, 4b, 4C
Four light receiving elements 7a, 71), 7C correspond to 14d.
It is composed of 17d and 7t. Reference numeral 10 is a light control plate which is a main part of the present invention. As shown in FIG. 6, this light control plate 1D has a liquid crystal material 1 sandwiched between the upper glass substrates 11.120, and further has upper and lower glass substrates 11.1.
2 is sandwiched between polarizing plates 14 and 15 to control the amount of light transmitted by the magnitude of the applied voltage, and the four light receiving elements 7a, 71), 7c
, 7d, the four segments 10a, 10b, 10c, 10
It is divided into d. In addition, in FIG. 2, this light control plate 1
0 is provided between the collimating lens 6 and the moving scale 1, but it may of course be provided at any position within the optical path from the light source 5 to the light receiving element 7.

In such a configuration, by controlling the voltage applied to each segment 10a, 10b, 10c, and 10d of the light control plate 10, each turn 2 of the moving scale 1 and each turn of the fixed scale 3 can be controlled. 4a, 4b,
When the bright portions of 71IC14d overlap, the amount of light received by each of the light receiving elements 7a, 7b, and 7C17d can be easily made equal.

Next, an example in which the photoelectric conversion device according to the present invention is applied to a detection unit of a C length measuring device will be described with reference to FIG. Incidentally, in FIG. 4, the same parts as in FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted.

Figure 4 is a side view of the detection unit of the length measuring device.
0 is a base block of the detection unit A, and 21 is a stem firmly connected to this base block 20. 22 is a plunger, one end of which is supported by the stem 21;
The other end can be adjusted by adjusting the voltage applied to each segment of the light control board instead of inserting the plunger 22K, allowing for fine adjustment control of the light amount.
The adjustment member for the applied voltage can also be placed at a distance from the light control board and in the same direction, making adjustment work easier.
This improves work efficiency. In addition, even when readjusting the light intensity during disassembly and reassembly, the light intensity can be adjusted by operating the adjustment member installed outside the optical path, without directly operating the light control board itself. is extremely large.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a conventional photoelectric conversion device, FIG. 2 is an exploded perspective view of a photoelectric conversion device of the present invention, FIG. 6 is a sectional view of a light control plate, and FIG. 4 is a photoelectric conversion device of the present invention. FIG. 2 is a diagram illustrating the main parts of the present invention applied to a detection unit of a length measuring device.

Claims (1)

[Claims] A moving scale having a light and dark pattern applied at equal intervals; a fixed scale facing the moving scale having a plurality of patterns that are identical to the pattern and mutually in phase; The scale is held between the light source installed on the moving scale side and the fixed school side (
A photoelectric conversion device (with a plurality of light-receiving elements corresponding to each of the plurality of patterns applied to the fixed school), in which the light emitted from the light source is A photoelectric conversion characterized in that a light control board made of a liquid crystal cell capable of controlling the amount of light to each of the light receiving elements is provided in the optical path through which light is received by each of the light receiving elements C through the school and the fixed school. Device.