JPH04369429A - Optical encoder - Google Patents

Abstract

PURPOSE:To obtain an optical encoder which prevents erroneous operation of a sensor part and can transmit signals by a single optical fiber in order to save costs. CONSTITUTION:An optical encoder has a shield plate which regulates the amount of light in three stages or more. The amount of light is converted to the intensity analog level of a photosignal in accordance with the regulating pattern of the shield plate, and detected by a detecting fiber 2. As a result, the combined state of, for example, phiA phase, phiB phase, phiZ phase and the like as an encoder is generated in accordance with the light intensity analog level at the detecting side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical encoder for optically detecting the angle and speed of a rotating body, and more particularly to an optical encoder suitable for use with optical fibers.

0002

[Prior Art] An encoder detects the angle, speed, and direction of a rotating body, and uses multiple signals such as a Z-phase signal for a reference point, and A-phase and B-phase signals for detecting the angle from the reference point. Because it has information, F of industrial robots, NC machine tools, etc.
It is widely used in the A field. Currently, there are optical encoders that use optical fibers in the transmission section in order to prevent malfunctions due to electrical noise during signal transmission.

[0003] This type of encoder includes, for example, Japanese Patent Application Laid-Open No. 62
-222400 is mentioned. Further, as an example of the disk pattern, Japanese Patent Laid-Open No. 63-250521 can be mentioned.

0004

[Problem to be solved by the invention] Above, JP-A-62-2
In the conventional technology as disclosed in Japanese Patent No. 22400, the digital output signal of the encoder is converted into an optical signal and transmitted, so there is a possibility that the sensor portion of the encoder may malfunction due to noise. Although JP-A-63-250521 is an example of a disk pattern, there are multiple patterns, each of which transmits a signal using a different fiber, and the sensor part of the encoder may malfunction due to electrical noise. There is a possibility that it will happen.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical encoder that can transmit signals through a single optical fiber in order to prevent malfunctions in the sensor portion and to reduce the cost.

[0006]

[Means for Solving the Problems] The above object is to construct a device with one light-emitting fiber that sends light and one light-receiving fiber that sends back the intensity of the light, without using an electrical circuit in the middle. This is achieved by

[0007]

[Operation] The light from a light-emitting element such as an LED is sent through a single fiber, and the amount of light is controlled through slits corresponding to the A, B, and Z phases of the encoder, thereby converting it into a strong or weak light amount. , this analog quantity of strength and weakness can be converted to another (or the same)
By sending the signal back through a fiber, there is no electrical circuit in the encoder section, so it is no longer affected by electrical noise, and the problem of malfunction can be solved.

[0008]

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a block diagram of an optical encoder circuit according to the present invention. A rotating disk 3 that transmits light from a light emitting element 8 through a light emitting fiber 1 and rotates around an axis 5.
The light receiving fiber 2 receives the light through both the slit 4 in the fixed disk 6 and the slit 7 provided in the fixed disk 6.
The light received by the light receiving element 9 is electrically amplified by the photoamplifier 10, and its output is used as an input signal to the waveform shaping circuits 12-16.

Each of the waveform shaping circuits 12 to 16 is configured to shape a waveform at a threshold level T1 to T5. For example, the waveform shaping circuit 1
2 is a well-known circuit consisting of operational resistors r7 and r8 and an amplifier 11 as shown in the figure. At this time, the threshold level T1 is constructed to be obtained by dividing the voltage of the power supply -V using a resistor dividing circuit of resistors r1 to r6 shown in the figure.

Other threshold levels can be similarly obtained between the calculated resistors r2 to r6. The outputs of the waveform shaping circuits 12 to 16 are E, D, and C, respectively.
, B, and A phases. The inverted B phase obtained by inverting the B phase by the NOT circuit 17, the E phase and the D phase are input to an AND circuit 19, and its output is designated as φA. In addition, the E phase is connected to the knot circuit 18.
The inverted E phase and the C phase are input to the OR circuit 20, and the output thereof is designated as φB. It is configured so that the A phase is directly used as φZ.

[0011] In this embodiment configured as described above,
Next, we will discuss the operation. The pattern of the slits 4 provided on the rotary disk 3 of FIG. 1 is shown in plan in FIG. Since the amount of light changes according to the slit pattern,
The light sent from the light emitting element 8 via the light emitting fiber 1 is converted into an analog quantity, i.e., the strength of the light, corresponding to the size of the slit 4 of the rotary disk 3.

Therefore, a slit 7 provided in the fixed disk 6
The amount of light that enters the light-receiving fiber 2 through the light-receiving element 9
The light is received by the photoamplifier 10 and electrically amplified by the photoamplifier 10. By extending the light-emitting fiber 1 and the light-receiving fiber 2 in this manner, the encoder portion and the electrical processing circuit portion can be completely separated.

FIG. 2 shows the photoamplifier output corresponding to the slit pattern. Since they are analog quantities as shown in the figure, the threshold levels T1, T2, T3,
When the waveforms are shaped by the waveform shaping circuits 12 to 16 at T4 and T5, signals A, B, C, D, and E as shown in FIG. 2 are obtained. Therefore, the B phase is inverted by the knot circuit 17, and the D
By ANDing the phase and E phase together with the AND circuit 19, encoder output φA is obtained. In addition, the E phase is connected to the knot circuit 1.
8 and is ORed by the C phase and the OR circuit 20 to obtain the encoder output φB. Waveform shaping circuit 1
The A phase which is the output of 6 becomes the encoder output φZ as it is. The above situation is summarized in FIG. 2.

According to this embodiment, the encoder signals φA, φB, and φZ phase signals can be identified using one optical fiber on the light emitting side and one optical fiber on the light receiving side, and at the same time,
By extending the optical fiber, the sensor part of the encoder and the electrical processing part can be separated.
Malfunctions caused by electromagnetic noise can be prevented.

Another embodiment of the invention is shown in FIG. The difference from FIG. 1 is that a reflection mirror 21 is placed on the fixed disk 6.
By providing the slit 4, the light transmitted through the slit 4 is reflected and received. Therefore, the light-emitting fiber 1 and the light-receiving fiber 2 can be placed on one side, so the structure is simple and the encoder can be easily assembled.

Another embodiment of the invention is shown in FIG. The difference from FIG. 1 is that a reflective surface 22 is provided on the rotary disk 3 by printing. Therefore, the structure can be simplified because the sensor and the disk can be configured to face each other on one side. The operation is the same as the example shown in FIG. 1, so a description thereof will be omitted. In this embodiment, since the rotary disk is created by printing, an inexpensive encoder can be realized.

Other embodiments of the present invention are shown in FIGS. 5 and 6. Although it is similar to the reflective type modification shown in FIG. 4, the difference from the previous example is that the printing pattern on the rotary disk 3 is a pattern without zero points as shown in FIG. Since this can be clearly understood by comparing it with FIG. 2, it will be explained in comparison with FIG. In FIG. 6, the output of the photoamplifier 10 can be distinguished into four levels, so the threshold levels are T1 to T4.

When the outputs of the photoamplifier 10 are waveform-shaped at threshold levels T1 to T4, four outputs are obtained: D-phase, C-phase, B-phase, and A-phase. The configuration of FIG. 5 is almost the same as that of FIG. 1 up to the waveform shaping circuit. The only difference is that the threshold level T5 is not required.

In FIG. 5, the inverted B phase and D phase obtained by inverting the B phase by the NOT circuit 17 are input to an AND circuit 23, and the output thereof is used as the encoder signal φA. The C phase is configured to be an encoder signal φB, and the A phase is configured to be an encoder signal φZ. With this configuration, a time chart as shown in FIG. 6 can be obtained. The encoder signals φA, φB, and φZ are as shown in the figure, and the same results as in FIG. 2 can be obtained. In this embodiment, the electric circuit section can be made simpler than in FIG.

Another embodiment of the invention is shown in FIG. symbol 1
to 10 are the same as in FIG. What differs from FIG. , φB, and φZ.

The processing within the microcomputer 24 at this time is shown in FIG. 8 as a flowchart. First, the output Pn of the photoamplifier 10 is taken in via the A/D converter 25 (S1),
It is compared with the threshold level T1 (S2), and if it is larger than T1, the E phase is set (S3), and if it is smaller than T1, the E phase is cleared (S4) and φB is set (S3).
5). According to the flow, when the analog input Pn is greater than T2 (Y at S6), the D phase is set (S7), and when it is smaller (N at S6), the D phase is cleared (S8). Pn is T
When larger than 3 (Y in S9), encoder output φB
(S10), and if it is small (N at S9), E
When the phase has already been cleared (Y in S11), φB
is set (S12), and when the E phase is not cleared yet (N in S11), φB is cleared (S13).

Next, when Pn is larger than T4 (S14
(Y in S16), clears the encoder output φA (S15), and when it is small (N in S14), if both the D and E phases have already been set (Y in S16, Y in S17), sets φA (S18). ), otherwise (N in S16,
(N in S17) and clears φA (S19). Next, P
When n is larger than T5 (Y in S20), encoder output φZ is set (S21), and when it is smaller than T5 (S2
0 (N), and clears φZ (S22).

The above operation is the same as the time chart in FIG. 2, and the encoder outputs φA, φB, φZ are
It is output from the microcomputer 24 via the port section 27. By setting the threshold levels T1 to T5 as constants in the microcomputer 24, external hardware input can be omitted, thereby simplifying the circuit. In this case, the thread levels T1 to T5 can be adjusted by adjusting the levels according to the speed of the encoder or the amount of light of the light emitting element.
More accurate judgment becomes possible. Since this embodiment uses a microcomputer, it has a feature that the circuit configuration is simple.

As another embodiment of the present invention, FIG. 9 shows an example in which the same circuit as in FIG. 7 described above is modified in software. FIG. 9 shows a software version of the operation corresponding to the time chart in FIG. First, the analog input Pn is fetched (S31), and if the difference between the twice read value Pn and Pn-1 is smaller than the predetermined tolerance ε (Y in S32), the current fetched value Pn and the previous fetched value Pn-1 The average value of the two is regarded as the analog input Pn (S33).

By doing this, it becomes possible to prevent the transient value of Pn from being erroneously determined. When Pn is greater than threshold level T1 (Y in S34)
, D phase is set (S35), and when it is small (N in S34).
), the D phase is cleared (S36). When Pn is larger than T2 (Y in S37), the encoder output φB is set (S38), and when it is smaller (N in S37), φB is cleared (S39). When Pn is greater than T3 (S4
0 (Y), clear φA (S41), and when small (
(N in S40), if the D phase has already been set (S42
(Y), sets φA (S43), and if the D phase is not set (N in S42), clears φA (S44).
). When Pn is larger than T4 (Y in S45), φZ
(S46), when it is small (N in S45), φZ
is cleared (S47). The above operation is similar to that in FIG. Then, encoder outputs φA, φB, and φZ are outputted via the I/O port.

[0026] In the present invention, as the encoder output,
Although the two-phase output of φA and φB is explained as an example, by making the slit pattern on the rotating disk 3 a continuous pattern, it is possible to increase the threshold level from T1 to Tn (n is an integer). Therefore, it can be easily estimated that it can also be applied as an absolute value encoder. This embodiment is characterized in that the processing steps are shorter than that in FIG.

[0027]

[Effects of the Invention] According to the present invention, one light-emitting fiber,
Since the signal can be transmitted using one pair of fibers on the light receiving side, the cost is low. In addition, by extending the optical fiber for a long time, the sensor part no longer has an electrical circuit.
This operation can be prevented from occurring due to noise. Furthermore, by utilizing the principles of the present invention, it can also be applied to absolute type encoders.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a time chart explaining the operation.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 6 is a time chart showing the operation of the embodiment.

FIG. 7 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 8 is a flowchart showing the operation of the embodiment.

FIG. 9 is a flowchart showing a modification of the operation of the fifth embodiment.

[Explanation of symbols]

1 Light-emitting fiber 2 Receiving side fiber 3 Rotating disk 4 Slit 8 Light emitting element 9 Photo receiving element 11 Amplifier 12-16 Waveform shaping circuit

Claims (6)

[Claims] Claim 1: An optical encoder having a shielding plate between one light-emitting fiber and one light-receiving fiber, which adjusts the light intensity in three or more stages, wherein the light intensity is adjusted according to the light intensity adjustment pattern of the shielding plate. Accordingly, the strength of the optical signal changes to an analog level, and the light is received by the light-receiving fiber, and on the receiving side, depending on the strength and weakness analog level of the light, φA phase, φB phase, φZ
An optical encoder characterized in that it generates a combination state of each phase as an equivalent encoder. [Claim 2] The amount of light from one light-emitting fiber is
The optical signal is converted into an analog level of strength and weakness according to the pattern for adjusting the light intensity in three or more stages provided on the reflector plate, and is received by a single light receiving fiber. An optical encoder characterized in that it generates combinations of phases such as φA phase, φB phase, φZ phase, etc. as an encoder. 3. An optical encoder having one light-emitting fiber, one light-receiving fiber, and a shielding plate or a reflecting plate that adjusts the amount of light in three or more levels, wherein the amount of light is adjusted by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by adjusting the amount of light by controlling the Depending on the light intensity adjustment pattern,
The optical signal is converted into an analog level signal, which is received by the light-receiving fiber, and the receiving side regenerates a signal with three or more levels by shaping the waveform according to the analog level of the optical signal. In combination, φA phase, φB phase,
An optical encoder characterized in that it generates an encoder signal such as a φZ phase. 4. One light-emitting fiber, one light-receiving fiber, and 4 fibers D, C, B, and A in descending order of light intensity.
In an optical encoder that has a shielding plate or a reflecting plate that is adjusted in stages, the amount of light is
According to the light intensity adjustment pattern of the stages, the optical signal is converted into a strong/weak analog level, the light is received by the light receiving fiber, and the waveform is shaped according to the light strong/weak analog level on the receiving side, thereby inverting the above B. An optical encoder characterized in that φA phase is generated by ANDing B and D, φB phase is generated by C, and φZ phase is generated by A. 5. One light-emitting fiber, one light-receiving fiber, and zero light intensity, E, D,
In an optical encoder that has a shielding plate or reflecting plate that can be adjusted in 5 stages of C, B, and A, the light intensity is converted into an analog level of the strength of the optical signal according to the 5-stage light intensity adjustment pattern of the shielding plate or the reflecting plate. Then, by receiving the light with the light receiving fiber and shaping the waveform according to the strength/weakness analog level of the light on the receiving side, the φA phase is inverted by ANDing the inverted B, which is the inverted version of B, and D and E. An optical encoder characterized in that a φB phase is generated by ORing with inverted E or C, and a φZ phase is generated by A. 6. In an optical encoder having one light-emitting fiber, one light-receiving fiber, and a shielding plate or a reflecting plate for adjusting the amount of light, the amount of light is adjusted according to the light amount adjustment pattern of the shielding plate or the reflecting plate. Accordingly, the optical signal is converted into a strong/weak analog level and received by the light receiving fiber. On the receiving side, the light strong/weak analog level is input to a microcomputer, and the microcomputer software converts the encoder output φA, φB, φZ phase, etc. An optical encoder characterized in that it generates an output signal.