JPS6076612A - Optical rotary encoder - Google Patents

Abstract

PURPOSE:To obtain output pulses, whose duty ratio is 1:1, by optically forming a reference electric signal, which is to become a comparing level of an encoder circuit, as a specified signal, and offsetting the leaking factor of dark currents and the like. CONSTITUTION:A plurarity of first slits 3, are arranged on a concentric circle at a specified interval on a rotary disk 1. An opening hole part 4 is provided on the concentric circle of the first slits on the rotary disk 1. A fixed slit plate 5 has a second slit 6, whose size is the same as that of the first slit 3, and a third slit 7, whose area is 1/2 that of the slit 6. Light from a first light source 8 is received by a first light receiving element 9 through the second slit 6 and the first slit 3. Light from a second light source 10 is received by a second light receiving element 11 through the third slit 7 and the opening hole part 4. Therefore, a reference electric signal, which is to become a comparing level of an encoder circuit, can be optically formed. The leakage factor of dark currents and the like can be offset. Output pulses having a duty ratio of 1:1 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention is a comparative example of an optical encoder circuit.

[Background technology]

Conventionally, D-talien coaters used in sensor technology, photoelectric conversion technology, etc., electrically generate the comparison level of the encoder circuit by resistor division, etc., so the duty of the output waveform may be affected due to leakage factors such as dark current of the light receiving element. It had the disadvantage that the ratio was different.

[Purpose of the invention]

An object of the present invention is to optically generate a reference electric signal serving as a comparison level as a constant signal, and to offset leakage factors such as dark current of the photoelectrically converted signal.

[Disclosure of the invention]

Embodiment In FIG. 1, (1) is a rotating disk, and the rotating shaft (2
), which has a plurality of first slits (31) arranged at regular intervals on a concentric circle, and an opening (4) concentrically with the first slit (31) as shown in FIG. The 7-rotation fastener fi+ provided in this manner is formed of a glass plate that has been cut into a co-width, and is etched to form the first slit +31 and the opening (4).(6) is a fixed slit plate that rotates. A second slit (6) having the same shape and area as the first slit (3) of the disk [+1],
A third slit (7) having an area % of that of the slit 3) or the second slit (6) is provided as shown in FIG.

Further, the radial length a of the opening (4) is made equal to the length b of the third slit 7). In a rotating disk, C
is the radial length of the first slit (3), d, d
' is the width between the first slits (31), e and e' are the widths of the I-th slit (3), and e=d, e'=d'. (8
) is the light source of Tomari 1, which passes through the second slit (6) and the first slit 3) to the first light receiving element (9).
1101 is a second light source, and the light is received by the second light receiving element (+1) through the third slit (7) and the aperture (4). Therefore, the first slit (
The amount of light received by the first light receiving element (9) when 31 and the second slit (6) completely match and overlap is the amount of light received through the aperture (4) and the third slit (7). The amount of light from the second light-receiving element (1) is twice that of the second light-receiving element (1
is constantly receiving light of this magnitude.

Figure 4 shows the Nijicoater circuit, where i9+ and (II) are the aforementioned first and second light receiving elements, respectively, and ++21p.
Q31 has first and second light receiving elements +91, respectively;
(A current-voltage conversion circuit that converts the photocurrent by Ill into voltage, 04) is a comparator.

Operation The second light receiving element (II) always receives the amount of light A that the first light receiving element (9) receives when the first slit (3) and the second slit (6) are perfectly aligned. Therefore, voltage vb in FIG. 5(a) appears at terminal B in FIG. On the other hand, the amount of light received by the first light receiving element (9) changes due to the rotation of the rotating disk F11, and a triangular wave voltage Va shown in FIG. 5(a) appears at the terminal A in FIG. 4.

The comparator compares the voltages Va and Vb and outputs an output pulse as shown in Fig. 5(b)6.In Fig. 5(a), α=β
, and r is the leakage voltage due to Va and vb.

Since the reference level of the terminal B of the comparator H is optically created, leakage factors such as dark current of the first light receiving element (9) and the second light receiving element (Ill) are almost canceled out. Compared to the case where the reference level is created electrically by resistor division, etc., it is possible to accurately compare the peaks of the waveform from the first light receiving element (a) and the values outside the peaks, and the output waveform has a duty ratio of I to l. output pulses can be obtained.

〔Effect of the invention〕

As described above, the present invention provides a rotating disk having a plurality of first slits arranged in parallel at regular intervals on a concentric circle, and an opening section provided on a concentric circle with the first slit, and the first slit. and a fixed slit plate having a second slit having the same dimensions as the first or second slit, and a third slit having an area outside the first or second slit. The first light receiving element receives light through the first slit, and the light from the second light source is received by the second light receiving element through the third slit and the opening. It is possible to optically create a reference electric signal, cancel out leakage factors such as dark current, and obtain an output pulse with a duty ratio of 1:1.

[Brief explanation of drawings]

Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is an enlarged front view with a portion of the above rotary disk cut away, and Fig. 3 is an enlarged front view with a portion of the fixed slot plate shown above cut away. Figure 4 is a circuit diagram of the same encoder circuit as above, Figure 15 (a),
(b) is a voltage waveform diagram of the main parts of the same as above. +I+... rotating disk, (3I... first slit, (41...
・Opening part, (5)...fixing slot plate, (6)...
・Second slit, (7)...Third slit, (8
1...First light source, (9)...First light receiving element, (1
o)...Second light source, [11] Light receiving element of both cylinders 2. Agent Patent Attorney Ishi 1) Chief 7 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) A rotating disk having a plurality of first slits arranged in parallel at regular intervals on a concentric circle, an opening section provided on a concentric circle with the first slit, and a first slit having the same dimensions as the first slit. 2 slit and % of said @1 or 2nd slit
a fixed slit plate having a third slit with an area of An optical zero-talien coater characterized in that the light is received by a second light receiving element through the third slot and the opening.