JPH0399221A - Optical rotary encoder - Google Patents

Abstract

PURPOSE:To decrease the number of components by outputting the two kinds of data of an angle signal and a reference signal as the signals whose light intensities are different in one series from one code pattern formed in a pulse scale. CONSTITUTION:A code pattern C0 for outputting optical pulse signal wherein an angle signal S1 and a reference position signal S2 are superimposed is formed in a pulse scale 1. Therefore, the optical pulse signal having the low peak level is outputted as the signal S1. The part of the signal which is superimposed on the signal S2 is outputted as the optical pulse signal having the high peak level. The optical pulse signal containing two kinds of data undergoes photoelectric conversion in a photodetector 5. The obtained pulse signal is inputted into a signal processing part 8 for discriminating between 1 and 0 of the signal S1 and a signal processing part 9 for discriminating between 1 and 0 of the signal S2. Since the signal S1 and the signal S2 can be taken out of the signal in one series, only one piece is enough for each of a light emitting element 4, the photodetector 5, a light emitting optical fiber 6 and a light receiving optical fiber 7. Thus the number of components can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical rotary encoder that detects the rotation angle of a pulse scale based on an angle signal corresponding to the rotation angle and a reference position signal representing 0 degrees.

[Conventional technology]

For example, when adjusting the ignition timing of a spark plug in an automobile engine or changing the ignition timing according to the rotational speed, an optical rotary encoder is used as a means for detecting the crank angle of the engine.

This optical rotary encoder, as shown in Figure 5,
Code pattern C for angle detection on pulse scale 1,
The code pattern C2 for detecting the reference position is formed concentrically in two rows, and the pulse signal of type 21) 1 is outputted at the same time.

Therefore, conventionally, from the two light emitting elements 5l and 52, via the two light emitting optical fibers 53 and 54,
Each code pattern CI and C2 is irradiated with light, and the light pulse signal outputted from these is sent to the light receiving optical fiber 55.
The angle signal SI and the reference position signal S2 are converted by photoelectric conversion by separate light receiving elements 57 and 58 via
was detected.

For example, in the case of a six-cylinder engine, the code pattern Cz is set so that the reference position signal S2 is output every time the pulse scale 1 rotates 60 degrees in order to discriminate between cylinders.
and generates the reference position signal S! The ignition timing is adjusted according to the number of pulses of the angle signal SI after the pulses are input.

The rotating shaft of the pulse scale 1 is connected to the engine crankshaft, and the control device 59, which is equipped with electronic components such as light emitting elements 5l and 52 and light receiving elements 57 and 58, which are sensitive to heat and vibration, is not connected to the engine crankshaft. It is located inside the dashboard of the driver's seat, and is protected from the direct effects of engine heat and vibration.

[Problem to be solved by the invention]

However, when two light-emitting elements 51 and 52 and two light-receiving elements 57 and 58 are provided, the individual optical connectors for connecting the light-emitting optical fibers 53 and 54 and the light-receiving optical fibers 55 and 56 are thick, so the control device There was a problem in that it was difficult to store the 59 in a narrow dashboard.

In other words, the 4-light pulse signal outputs only the rlJ and rOJ signals, so conventionally, in order to obtain two types of information, the angle signal and the reference position signal, two lines of code patterns were formed on pulse scale 1, and two lines of code patterns were formed on pulse scale 1. An optical system must be provided, so the light emitting elements 51 and 52 and the light receiving element 57
and 58 had to be provided, and there was a problem that the connecting portion could not be made smaller.

Furthermore, when the number of elements is large, the number of parts is also increased, which not only takes time and effort to assemble, but also increases costs.

Therefore, the present invention makes it possible to obtain two types of information, an angle signal and a reference position signal, from one optical pulse signal by simply providing one row of code patterns on the pulse scale, thereby reducing the number of parts. The goal is to reduce costs and further downsize the connection between the optical fiber and the control device.

[Means to solve the problem]

In order to solve this problem, the present invention outputs an angle signal according to the rotation angle and a reference position signal representing 0 degrees as an optical pulse signal by rotating a pulse scale, and outputs these angle signals and reference position signals as optical pulse signals. In an optical rotary encoder configured to detect the rotation angle of a pulse scale based on a reference position signal, a light-transmitting part or a light-reflecting part of a code pattern formed along the circumferential direction of the pulse scale is detected. Other light transmitting parts or light reflecting parts other than the specific light transmitting part or light reflecting part that outputs are formed so as to attenuate the transmitted light or reflected light, so that the peak level of the angle signal and the reference position signal is high. An optical pulse signal and an optical pulse signal with a low peak level that becomes an angle signal are output as a mixture, and based on the pulse signal obtained by photoelectrically converting the optical pulse signal, Suhars' The present invention is characterized in that it includes a signal processing unit that determines the angle signal rlJ rQj based on the presence or absence of an input, and a signal processing unit that determines the reference position signal rlJ rO depending on the presence or absence of the input of a high peak level pulse.

[Effect]

According to the present invention, among the light-transmitting parts or light-reflecting parts of the code pattern formed along the circumferential direction of the pulse scale,
Except for the specific light-transmitting part or light-reflecting part that outputs the reference position signal, other light-transmitting parts or light-reflecting parts are formed to attenuate transmitted light or reflected light, so the angle signal has a low peak level. An optical pulse signal is output, and a portion of the optical pulse signal that overlaps with the reference position signal is output as an optical pulse signal with a high peak level in a format in which optical pulse signals of different strengths and weaknesses are mixed.

After photoelectrically converting the optical pulse signal containing a mixture of these two types of information, the rl rQJ of the angle signal is determined based on the presence or absence of pulse input, and the rlJ of the reference position signal is determined based on the presence or absence of high peak level pulse input. rl
is determined and separated into an angle signal and a reference position signal.

That is, by irradiating one code pattern with light output from one light emitting element, one system of optical pulse signals containing two types of information consisting of a high peak level part and a low peak level part is output, A signal detected by one light receiving element can be separated into an angle signal and a reference position signal.

Therefore, the light-emitting element and the light-receiving element can be combined into one, and by reducing the number of parts, the assembly effort and cost can be reduced. It is possible to reduce the size of the connection part with the device.

C Embodiment] The present invention will be described below based on specific embodiments shown in the drawings.

FIG. 1 is a flow sheet showing the configuration of the present invention, FIG. 2 is an enlarged view showing the main part thereof, and FIGS. 3(a) to (Cl are graphs showing the output waveforms of pulse signals).

This example shows the case where it is applied to a transmission type optical rotary encoder, and the pulse scale 1 has a code pattern C0 in which slits 2.2, which serve as transparent parts, are provided at predetermined intervals along the circumferential direction of the pulse scale 1. has been admonished.

The slits 2.2-, . . . - are formed at 60 degree intervals, and attenuating films are formed in the other slits 2, excluding the specific slit 2a that outputs the reference position signal S2, to attenuate transmitted light.

That is, the code pattern C0 is formed by, for example, depositing chromium on the surface of a certain pulse scale 1 using a circular glass plate, and controlling the thickness of the chromium deposited at the slit 2 to form an attenuation film. specific slit 2a
Chromium is not vapor-deposited and is exposed as glass.

Therefore, an optical pulse signal with a low peak level is outputted as the angle signal S through the slit 2, and light with a high peak level is outputted as the angle signal S1 and the reference position signal S2 through the specific slit 2a. A pulse signal is output at a constant period, and is output as a single optical pulse signal containing a mixture of signals of different strengths and weaknesses. The control device 3 is provided with a pair of light-emitting element 4 and light-receiving element 5, one end of which is connected to the light-emitting element 4 and the light-receiving element 5, and the other end of the light-emitting optical fiber 6 and the light-receiving optical fiber 7,
It is arranged opposite to the code pattern C0.

The light receiving element 5 has a signal processing unit 8 that determines the rOJ rlJ of the angle signal S, and a signal processor 8 that determines the rOJ rlJ of the angle signal S, and the
It is connected to a signal processing section 9 that discriminates J.

A reference voltage setting circuit 8a is provided in the signal processing units 8 and 9.
and 9a are connected to each other.

The reference voltage V of the signal processing unit 8 of the angle signal S1 is set to a low peak level P. when only the angle signal Sl is input. A signal having a level higher than the reference voltage vl is determined to be rll.

In addition, the reference voltage ■2 of the signal processing unit 9 of the reference position signal S2
is set lower than the peak level P2 when the peaks of the angle signal S and the reference position signal S2 are input manually at the same time, and higher than the peak level P when only the angle signal Sl is input, and is set higher than the reference voltage v2. A high level signal is determined to be rlJ.

Therefore, as shown in FIGS. 3(a) to 3(C), the optical pulse signal (FIG. 3(a)) inputted to the light receiving element 5 with the angle signal S and the reference position signal S2 superimposed thereon is photoelectronically transmitted. The signal processing units 8 and 9 convert the angle signal S+(
3(b)) and the reference position signal S. (Figure 3 (C))
It can be separated into

Note that 10 is an arithmetic device that calculates the rotation angle by counting the angle signal S while referring to the reference position signal S2.

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

First, the light output from the light emitting element 4 is converted into a code pattern C.
0 and a code pattern C.
A light-receiving optical fiber 7 that guides the light pulse signal outputted from the light-receiving element 5 to the light-receiving element 5 is collectively connected to the control device 3 by a connector.

As a result, the optical fiber 6 is connected to the light emitting element 4 and the light receiving element 5.
Since the connector for connecting the control device 3 and the optical fibers 6 and 7 can be miniaturized, the control device 3 can be installed in a narrow dashboard with plenty of room, and the work of connecting the control device 3 and the optical fibers 6 and 7 is extremely simple. become.

Since the pulse scale 1 is formed with a code pattern Go that outputs an optical pulse signal on which the angle signal S and the reference position signal S2 are superimposed, an optical pulse signal with a low peak level is output as the angle signal S. The portion that overlaps with the reference position signal S2 is output as an optical pulse signal with a high pinpoint level.

Then, the optical pulse signal containing these two types of information is photoelectrically converted by the light receiving element 5, and the obtained pulse signal is used as a signal processing unit 8 for determining rlJ rOJ of the angle signal S,
The signal is input to the signal processing section 9 which determines whether the reference position signal S2 is "1" or "0".

Each signal processing section 8 and 9 sets the value of the reference voltage V and V2 to the peak level P I+ of the superimposed pulse signal.
Since the setting is made according to the difference in Pt, the angle signal S1 and the reference position signal S2 are separated from each other based on the difference, and the rOJ rlJ of each signal is determined separately and input to the arithmetic unit 10.

In addition, in the arithmetic unit 10, if two reference position signals "1" are input consecutively, it is determined to be 0 degrees, and if they are not consecutive, it is determined to be a cylinder discrimination signal that is output every 60 degrees. At the same time, the rotation angle is detected by counting the angle signal S, while referring to the reference position signal s2.

In this way, since the angle signal S1 and the reference position signal s2 can be extracted from the l system of signals, one light emitting element 4, one light receiving element 5, one light emitting optical fiber 6, and one light receiving optical fiber 7 are sufficient. , it is possible to reduce the number of parts and reduce costs, and at the same time it is possible to reduce the size of the connector.

FIG. 4 is an enlarged view showing the main part of another embodiment. In this embodiment, a specific slit 2a for outputting the reference position signal s2 is formed long in the diameter direction of the pulse scale. , the other slits 2 are formed short, and the peak level is changed by changing the amount of light transmitted through the slits 2 or 2a.

In this way, the short slit 2 can output an optical pulse signal with a weak peak level, and the long slit 2a can output a reference position signal with a strong peak level.

Further, if there is a margin in the circumferential direction, the amount of transmitted light can be similarly changed by changing the width of the slit.

In the embodiment, a transmission type optical rotary encoder has been described, but the present invention is not limited to this, and can also be applied to a light reflection type optical rotary encoder.
In this case, the reflected light intensity can be changed by roughening the surface of the light reflecting part formed along the circumferential direction of the pulse scale 1, or by changing the area of the light reflecting part that overlaps with the light irradiation area. Just change the intensity of the light.

〔Effect of the invention〕

As described above, according to the present invention, two types of information, an angle signal and a reference position signal, are output from one code pattern formed on a pulse scale as l systems of signals with different light intensities. Since it requires only a pair of light-emitting elements to irradiate light and light-receiving elements to detect optical pulse signals, it is possible to reduce the number of parts and reduce costs, while also making it easier to assemble and connect optical fibers. Since the number of elements has been reduced, the connection between the optical fiber and the control device can be made smaller, making it possible to fit into tight spaces. 1) It has the excellent effect of making it extremely easy to install the device.

[Brief explanation of drawings]

Fig. 1 is a flow sheet showing the structure of the present invention, Fig. 2 is an enlarged view showing the main parts, Fig. 3 (al to (C) is a graph showing the output waveform of the pulse signal, and Fig. 4 is a graph showing the output waveform of the pulse signal. Fig. 5 is a flowchart showing a conventional optical rotary encoder.Description of symbols 1--pulse scale, 2.2a--slit (transparent part) ), 3 --- control device,
4-- Light emitting element, 5-- Light receiving element, 6... Optical fiber for light emitting, 7... Optical fiber for light receiving, 8-...
Angle signal signal processing section, 9-.1 reference position signal signal processing section, IO..1 arithmetic unit, S, -.. angle signal, s2 - reference position signal, C0,
1.-Chord pattern, V. , V, -11 reference voltage, P,1 lower peak level, P2...higher peak level. Patent issuer Optec Didi Melco Laboratory Daiichi Denko Co., Ltd.

Claims (1)

[Claims] [1] By rotating the pulse scale (1), an angle signal (S_1) corresponding to the rotation angle and a reference position signal (S_2) representing 0 degrees are output as optical pulse signals. In an optical rotary encoder configured to detect the rotation angle of a pulse scale (1) based on an angle signal (S_1) and a reference position signal (S_2), a rotary encoder formed along the circumferential direction of the pulse scale (1) Among the light-transmitting parts (2) or light-reflecting parts of the code pattern (C_0), other light-transmitting parts (except for the specific light-transmitting part (2a) or light-reflecting part that outputs the reference position signal (S_2) 2) Or, a light reflecting part is formed to attenuate transmitted light or reflected light, and a light pulse signal with a high peak level, which becomes an angle signal (S_1) and a reference position signal (S_2), and an angle signal (S_1) Based on the pulse signal obtained by photoelectrically converting the optical pulse signal, the angle signal ( S_1) "1""0"
”, and a signal processing unit (9) that determines whether the reference position signal (S_2) is “1” or “0” depending on the presence or absence of input of a high peak level pulse. Features optical rotary encoder. [2] Among the transparent parts (2), the reference position signal (S_2
2. The optical rotary encoder according to claim 1, wherein an attenuation film is deposited on the light transmitting portions (2) other than the specific light transmitting portion (2a) that outputs the signal. [3] A specific transparent part (2a) or light reflecting part that outputs the reference position signal (S_2) is formed long in the diameter direction of the pulse scale, and other transparent parts (2) or light reflecting parts are formed short. The optical rotary encoder according to claim 1, wherein the optical rotary encoder is configured to change the peak level by changing the amount of light that is formed and transmitted or reflected. [4] Each of the signal processing units (8) and (9) is connected to a light receiving element (5) that photoelectrically converts an optical pulse signal, and converts the pulse signal input from the light receiving element (5) into its peak level. The reference voltage (V_1), (V_
2) to determine whether it is "1" or "0". The signal processing section for the reference position signal (
9), whose reference voltage (V_2) is set between the higher peak level (P_2) and the lower peak level (P_1), and the respective signal processing units (8) and (9) The optical rotary encoder according to claim 1, wherein the pulse signal input to the element (5) is separated into an angle signal (S_1) and a reference position signal (S_2).