JPH0399223A - Optical rotary encoder - Google Patents

Abstract

PURPOSE:To make only one photodetector suffice by receiving two kinds of signals outputted from a pulse scale with one photodetector, and splitting the signals into an angle signal and a reference position signal with a control device. CONSTITUTION:In a pulse scale 1, a code pattern C1 for outputting an angle signal S1 and a code pattern C2 for outputting a reference position signal S2 are formed. When the rotating angle of a crank is detected, the signal S1 is outputted through a receiving fiber 6, and the signal S2 is outputted through a receiving fiber. The signals are superimposed and inputted into a photodetector 8. The high level signal is outputted from the part where the peak parts of the waveforms are overlapped, and the low level signal is outputted at the part where only the angle signal is present. When the signals are inputted into a signal processing part 9 for the signal S1 and a signal processing part 10 for the signal S2, the signal S1 and the signal S2 are separated since the reference signal value is set in correspondence with the difference between the peak levels of the superimposed pulse signals. Therefore, 0 or 1 of each signal is discriminated. Then, the signals are inputted into an arithmetic unit 11.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is characterized in that a code pattern for detecting an angle and a code pattern for detecting a reference position are formed concentrically on a pulse scale, so that two types of pulse signals can be output at the same time. Regarding the output optical rotary encoder. [Prior Art] For example, an optical rotary encoder is used as a crank angle sensor to control the ignition timing of a spark plug in an automobile engine based on the engine crank angle, or to change the ignition timing according to the rotation speed. is used.

This optical rotary encoder, as shown in Figure 4,
Code pattern C for angle detection on pulse scale l,
A code pattern C2 for detecting the reference position is formed concentrically so that two types of pulse signals are output at the same time.

Therefore, conventionally, from two light emitting elements 31 and 32, via two light emitting optical fibers 33 and 34,
Each code pattern C, &C. The optical pulse signals outputted from these are sent to optical fibers 35 and 3.
6, the angle signal S1 and the reference position signal S2 are detected by photoelectric conversion using separate light receiving elements 37 and 38.

For example, in the case of a six-cylinder engine, the reference position W is set every time the pulse scale 1 rotates 60 degrees in order to discriminate between cylinders. Code pattern C so that three signals are output
The ignition timing ξ is determined according to the number of pulses of the angle signal S1 after the pulse of the reference position signal S2 is input.
They are being forced to adjust their management.

The rotation axis of the pulse scale 1 is connected to the crankshaft of the engine, and the light emitting element 31. which is sensitive to heat and vibration.
The control device 39, which includes electronic components such as 32 and light-receiving elements 37 and 38, is located in the dashboard of the driver's seat away from the engine, and is protected from being directly affected by the heat and vibrations of the engine. There is.

[Problem that the invention seeks to solve]

However, when two light-receiving elements 37 and 38 are provided, the optical connectors for connecting the light-receiving optical fibers 33 and 34 to these elements are thick, so the area occupied by the connector connection portion becomes larger in the entire device. There was a problem that it was difficult to store it in a narrow dashboard.

Therefore, the present invention has been developed to receive two types of signals output from a pulse scale with one light receiving element, and then electrically separate the two types of signals into an angle signal and a reference position signal using a control device. The goal is to reduce the number of light-receiving elements that were previously available to just one, and to downsize the coupling part to the optical fiber.

[Means to solve the problem]

In order to solve this problem, the present invention provides a pulse scale with an angle detection code pattern that outputs an angle signal corresponding to the rotation angle as an optical pulse signal, and a reference position detection signal representing 0 degrees as an optical pulse signal. The code patterns for position detection that are outputted as a code pattern are concentrically formed, and the code pattern includes a light emitting element that irradiates light to each code pattern, and a light receiving element that photoelectrically converts the optical pulse signal output from each code pattern. A control device compares the pulse signal output from the light receiving element with a reference voltage and determines the r of the angle signal and reference position signal.
In the optical rotary encoder provided with a pair of signal processing units for determining Qj rlJ, the control device includes:
One light-receiving element is provided to simultaneously photoelectrically convert two types of optical pulse signals output from each code pattern of the pulse scale, and the light-receiving element is connected to each of the signal processing sections to convert angle signals rOJ rlJ. The reference voltage of the signal processing section that discriminates is set lower than the peak level when only the pulse of the angle signal is input, and the reference voltage of the signal processing section that discriminates rOJ rlJ of the reference position signal is set lower than the peak level when only the pulse of the angle signal is input. and the reference position signal pulses are input at the same time, and higher than the peak level when only the angle signal pulses are input, and each signal processing unit outputs from the light receiving element. It is characterized in that the generated pulse signal is separated into an angle signal and a reference position signal.

[Effect]

According to the present invention, the angle signal and the reference position signal are synchronously output from the pulse scale, and these are photoelectrically converted by one light receiving element, so the two optical pulse signals are superimposed, and the angle The waveform has a low peak level in a portion where only the signal is output, and a high peak level in a portion where the angle signal overlaps with the reference position signal.

In the signal processing section for the reference position signal, the reference voltage is set lower than the peak level when the reference position signal and angle signal are input at the same time, and higher than the peak level of only the angle signal. Only reference position signals having a peak level higher than the reference voltage will be detected.

In addition, in the angle signal signal processing section, the reference voltage is set lower than the peak level of the angle signal, so even if only the angle signal is output, the angle signal and reference position signal are input at the same time. The angle signal can be detected regardless of its peak height.

In this way, even if the angle signal and reference position signal are input at the same time, each signal processing section reliably separates them.
The rotation angle can be detected in the same manner as before.

Therefore, the number of light receiving elements can be reduced to one, and it is possible to reduce the size of the connecting portion between the optical fiber and the control device, and at the same time, it is possible to reduce the cost by reducing the number of elements.

〔Example〕

Hereinafter, the present invention will be explained based on specific embodiments shown in the drawings.

Figure 1 is a flow sheet showing the configuration of the present invention, Figure 2 (a
) to (C) are graphs showing output waveforms of pulse signals.

Note that parts that overlap with those in FIG. 4 are given the same reference numerals and detailed explanations are omitted.

The pulse scale 1 includes a code pattern C that outputs an optical pulse signal according to the rotation angle, an optical pulse signal that serves as a reference position signal indicating 0 degrees of the pulse scale 1, and an optical pulse for cylinder discrimination every 60 degrees. A code pattern C2 for outputting a signal is formed concentrically. The m control device 2 includes one light emitting element 5 that irradiates light to each code pattern C and C2 formed on the pulse scale 1 via light emitting optical fibers 3 and 4, and the code pattern C and One light receiving element 8 is provided which receives the angle signal S1 and the reference position signal S2 outputted from C2 via light receiving optical fibers 6 and 7, respectively.

This light-receiving element 8 photoelectrically converts the optical pulse signal in which the angle signal SI and the reference position signal S2 are combined, and the signal processing unit that determines whether the pulse signal is "O" or "1" of the angle signal S. 9 and the reference position signal Sz. rOJ rl
The signals are connected to the signal processing unit 10 for determining J, so as to be inputted thereto.

Reference voltage setting circuits 9a and 10a are connected to the signal processing sections 9 and 10, respectively. Signal processing section 9
The reference voltage V, is set lower than the peak level P, when only the angle signal S1 is input, and a signal having a level higher than the reference voltage V1 is determined to be "1".

Further, the reference voltage (2) of the signal processing section 10 is the angle signal SI
and the peak level P2 when each pulse of the reference position signal S2 is input at the same time, and higher than the peak level P when only the angle signal is input, and the level higher than the corresponding base 4 voltage ■2. The signal is determined to be "1".

Therefore, as shown in FIG. 2 (al to (C)), the pulse signal (FIG. 2 (a)) output from one light receiving element 8 with the angle signal S. and the reference position signal S2 superimposed, is
The angle signal S+ (second
It can be separated into the reference position signal SZ (FIG. 2(C)) and the reference position signal SZ (FIG. 2(C)).

Note that 11 is an arithmetic device that counts and calculates the rotation angle while comparing the angle signal Sl with the reference position signal S2.

In the arithmetic unit 11, if two reference position signals Sz rlJ are input consecutively, it is determined to be 0 degree, and if they are not consecutive, it is determined to be a cylinder discrimination signal every 60 degrees, and the reference position signal is determined to be 0 degrees. The rotation angle is detected by counting the angle signal S while referring to S2.

FIG. 3 is a sectional view showing a connector 12 for collectively connecting the light emitting optical fibers 3 and 4 and the light receiving optical fibers 6 and 7 to the light emitting element 5 and the light receiving element 8, respectively. A ferrule 13 into which the optical fibers 3 and 4 are fitted, and a ferrule 14 into which the light receiving optical fibers 6 and 7 are fitted,
The tightening napft 15, which is provided to face the light emitting element 5 and the light receiving element 8, is screwed into the threaded part 16a of the receptacle 16 fixed to the control device 2, thereby connecting the control device 2 and each optical fiber 3. , 4 and 6, 7 are connected together.

The above is an example of the structure of the present invention, and its operation will be explained next.

The pulse scale 1 is formed with a code pattern C1 that outputs the angle signal SI and a code pattern C2 that outputs the reference position signal S2, and light-emitting optical fibers 3 and 4 that irradiate these with light. The light-receiving optical fibers 6 and 7 that receive the optical pulse signals output from each code pattern are collectively connected to the control device 2 via the connector 12.

Therefore, not only is the connection work extremely simple, but since there is only one light emitting element 5 and one light receiving element 8 each, the connector l2 can be made compact, and it can fit comfortably in a narrow dashboard. can be installed.

When detecting the rotation angle of the crank, one light receiving optical fiber 6 outputs an angle signal S, and the other light receiving optical fiber 7 outputs a reference position signal St, and these are superimposed. Since it is input to one light receiving element 8,
As shown in FIG. 2 (al), the waveform becomes high level where the peak portions overlap, and in the case of only the angle signal, a low level signal is output.

When these are input to the signal processing section 9 for the angle signal S1 and the signal processing section 10 for the reference position signal S2, the reference voltage V. The value of 2 is the peak level P. of the superimposed pulse signal. ,P. Since it is set according to the difference between
After the angle signal S, and the reference position signal S2 are separated, and "0" and "l" of each signal are determined, each arithmetic unit
1 is input.

Therefore, the two superimposed signals are transmitted to one light receiving element 8.
can be reliably detected.

In the embodiment, a transmission type optical rotary encoder has been described, but the present invention is not limited thereto, and can also be applied to a reflection type optical rotary encoder.

In addition, one light emitting optical fiber is connected to the light emitting element 5,
Barusuke. - An optical branch path is provided in the vicinity of the code pattern C, , C. At the same time, each code pattern C,,C. The optical pulse signal outputted from the light receiving element 8 may be inputted into one light receiving optical fiber via an optical multiplexing path, and this light receiving optical fiber may be connected to the light receiving element 8.

〔Effect of the invention〕

As described above, according to the present invention, superimposed pulse signals can be separated using a circuit similar to the conventional circuit, so it is possible to reduce costs by reducing the number of elements by using only one light receiving element. At the same time, the connecting part between the optical fiber and the control device 4'B can be made compact, and the control device can be installed even in a narrow space, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an embodiment of the present invention, FIGS. 2(a) to (C) are graphs showing output waveforms of pulse signals,
FIG. 3 is a sectional view showing an example of a connector, and FIG. 4 is a flow sheet showing a conventional device. Explanation of symbols■・-Pulse scale, 2.--Control device 3, 4.--Optical fiber for light emission, 5.--Light emitting element 6. 7-
Optical fiber for light reception, 8--Light-receiving element 9--Signal processing unit for one-angle signal, 10--Signal processing unit for reference position signal, S. --One angle signal, s2-...Reference position signal, C +, C t
-・-Code pattern, V,,V,...Reference voltage. P
．． , P2 - peak level

Claims (1)

[Claims] An angle detection code pattern (C_1) that outputs an angle signal (S_1) corresponding to the rotation angle as an optical pulse signal on the pulse scale (1), and a reference position detection signal (S_2) representing 0 degrees as an optical pulse signal. A position detection code pattern (C_2) is formed concentrically, and a light emitting element that irradiates light to each code pattern (C_1), (C_2) and each code pattern (C_1), (C_2) are formed concentrically.
A control device (2) equipped with a light receiving element that photoelectrically converts the optical pulse signal output from the light receiving element compares the pulse signal output from the light receiving element with a reference voltage and generates an angle signal (S_1).
and a pair of signal processing units (9) and (10) for discriminating “0” and “1” of the reference position signal (S_2). 1) each code pattern (C_1), (
One light-receiving element that simultaneously photoelectrically converts two types of optical pulse signals output from C_2) is provided, and the light-receiving element is connected to each of the signal processing units (9) and (10) to convert the angle signal. The reference voltage (V_1) of the signal processing unit (9) for determining "0" and "1" is set lower than the peak level (P_1) when only the pulse of the angle signal (S_1) is input, and "0" of the reference position signal (S_2) "
The reference voltage (V_2) of the signal processing unit (10) that determines
) is the peak level (P_
2) It is set lower than the peak level (P_1) when only the pulse of the angle signal (S_1) is input, and the signal processing units (9) and (10) An optical rotary encoder characterized in that a pulse signal output from the optical rotary encoder is separated into an angle signal (S_1) and a reference position signal (S_2).