JP3309293B2 - Rotary encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder for detecting a rotational position of a rotating body, and more particularly to a rotary encoder having excellent fail-safe characteristics.

[0002]

2. Description of the Related Art For example, in a mechanical press in which a slide is reciprocated by rotating a crank by a motor, as a safety measure for work, a signal for confirming that the slide has temporarily stopped at a top dead center, a signal for stopping the slide, and the like. A signal for confirming the function (braking performance), a signal indicating that the slide is in the ascending process, and the like are generated. The position information of these slides is given by a crank angle signal. The angle signal is also used when regulating the movable range of the arm of the industrial robot.

Therefore, in the control of such a mechanical press or a robot, a high fail-safe property (a characteristic that does not generate an erroneous angle signal) is required for the generation of the angle signal. As a device for generating such an angle signal, there is a rotary encoder. The rotary encoder encodes and outputs an arbitrary angle signal as position information of the rotating body, and generates a desired angle signal to be detected by logically processing the angle signal. Rotating the rotating disk, which has a transmitting part and a shielding part that shields light in a predetermined pattern, is rotated in synchronization with a rotating body that detects the rotational position, and both sides of the rotating disk correspond to the number of code bits. A number of light emitting elements and light receiving elements are arranged.

[0004] With the rotation of the rotating disk, according to the pattern of the transmitting part and the shielding part, the output of the logical value 1 is received from the light receiving element that receives the light through the transmitting part, and the light is shielded by the shielding part. By generating an output of a logical value 0 from the light receiving element, an arbitrary angle signal of the rotator can be converted into 2 bits of 1 and 0.
It is output in correspondence with a binary code signal having a predetermined number of bits consisting of a value. The signals constituting the binary code signal output from the angle signal generating unit are converted into binary signal (1, 1) of a two-wire system in which logical values 1 and 0 are dual.
0) and (0, 1), and a dual signal of each bit is logically processed to generate a desired angle signal.

The reason why the binary code signal is converted into a two-wire system signal is that it is necessary to distinguish between a normal state and an erroneous state. That is, the output of a logical value 1 indicating presence of light is a binary signal (1, 0) in which logical values 1 and 0 are dual, and the output of logical value 0 indicating no light is a binary signal in which logical values 1 and 0 are dual. By converting the signals to signals (0, 1) and generating an output of logical value 1 even when there is no light, it can be confirmed that the signals are in a normal state.

[0006]

In the two-line processing for generating the two-line signal (0, 1) from the output of the logical value 0, the output of the logical value 0 is negated and the logical value 1 is generated. Inevitably, the conversion process includes a negation operation. Thus, if the signal processing involves a negation operation,
For example, when a disconnection fault occurs on the input side of the NOT operation circuit, the output signal becomes a logical value 1 and the output becomes a logical value 1 when the fault occurs.
Error occurs, and a fail-safe configuration is not achieved.

[0007] Therefore, in order to obtain a fail-safe two-wire system signal, for example, a signal generator disclosed in Japanese Patent Application Laid-Open No. 5-133728 has been proposed. In this device, a two-line signal is directly obtained by using both a transmission type sensor having a logical value of 1 upon receiving transmitted light and a reflective type sensor having a logical value of 1 upon receiving reflected light. That is, when the transmissive portion passes along with the rotation of the rotating body, the logical output of the transmissive sensor becomes 0 →
1 and the logical output of the reflective sensor changes from 1 to 0, and when the shield passes, the logical output of the transmissive sensor changes from 0 to 1 and the logical output of the reflective sensor changes from 0 to 1. The output changes from 0 to 1. Accordingly, the output of each sensor is a dual binary output, and in this case, a fail-safe angle signal can be generated without including a negative operation.

When a fail-safe rotary encoder is constructed, such a fail-safe two-wire system signal is generated, and all of the signals constituting a binary code signal indicating a desired angle signal to be detected are generated. It is necessary to confirm that is output normally. Therefore, the present invention has been made in view of the above circumstances, and uses a fail-safe two-wire system signal to output a desired angle signal to be detected while confirming whether or not these are output normally. It is an object of the present invention to provide a rotary encoder having the above configuration.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a rotary encoder for detecting a rotational position of a rotating body, wherein a signal transmitting portion and a signal shielding portion are formed in a predetermined pattern and are synchronized with the rotating body. A rotating rotating disk, and signal generating means for generating an AC output having a logical value of 1 when receiving a signal and a logical value of 0 when not receiving a signal by passing the signal transmitting portion and the signal shielding portion with rotation of the rotating disk. A binary code signal having a predetermined number of bits is generated by the signal generating means with the rotation of the rotating disk from the signal generating means, wherein each bit is a binary signal having two logical values of 1 and 0, respectively. Rotation angle signal generation means for obtaining a rotation angle position signal of the rotating body; addition operation means for performing addition operation on an output logical value of a binary code signal of the rotation angle signal generation means corresponding to a desired detected angular position; At the time of the outbreak faulty output of logic value 1 when the threshold or more addition operation value is set in advance of the operation means is constituted by a threshold value calculating means as the output of logic value 0.

The signal generation means of the rotation angle signal generation means has a four-wire system configuration for generating an anti-phase signal for each of the two-wire system signals.

[0011]

In this configuration, when the rotating disk rotates with the rotation of the rotator, a binary code of a predetermined number of bits indicating the rotation position is sent from the rotation angle signal generating means in accordance with the formation pattern of the signal transmitting portion and the signal shielding portion. A signal is generated. Each bit of this binary code signal is composed of a two-line binary signal in which logical values 1 and 0 are dual. Among the output binary code signals, the output logic value of each bit of the code signal corresponding to the desired detection angle position to be detected is added by the addition operation means. The threshold value calculating means compares the added value with a preset threshold value, and when the value is equal to or larger than the threshold value, outputs a logical value of 1 as the normal rotation body position information.
Here, since the threshold value calculating means has a configuration in which the output becomes a logical value 0 at the time of failure, fail-safe property can be ensured.

Further, the signal generation means of the rotation angle signal generation means has a four-wire system configuration for generating an anti-phase signal for each of the two-wire system signals, thereby simplifying the circuit configuration of the addition operation means. become able to.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a first embodiment of a rotary encoder according to the present invention. In FIG. 1, a rotary encoder according to the present embodiment converts a binary code signal consisting of a two-line binary signal representing the angular position of a rotating body with the rotation of a rotating disk that rotates in synchronization with the rotation of a rotating body. A rotation angle signal generating circuit 1 as a generated rotation angle signal generating means,
An output terminal of a signal representing a desired angular position to be detected among the outputs of the rotation angle signal generation circuit 1 is connected, and an addition circuit 2 as an addition operation means for performing an addition operation on output logic values of these output terminals, The threshold value calculating means for comparing the addition value of the circuit 2 with a preset threshold value and generating an angle detection output of a logical value 1 when the binary code signal output from the rotation angle signal generation circuit 1 is normal when the value is equal to or larger than the threshold value And the threshold value calculation circuit 3.

Next, the configuration of the rotation angle signal generation circuit 1 will be described in detail with reference to FIGS. In FIG. 2, a rotating shaft 1 as a rotating body which is a body to be detected at a rotating position is shown.
At 0, a rotating disk 11 having a light transmitting portion 11A (white portion in the drawing) and a shielding portion 11B (black portion in the drawing) formed in a predetermined pattern as shown in FIG. 3 is fixed. In this embodiment,
The transmitting portion 11A and the shielding portion 11B of the rotating disk 11 form a pair in the radial direction of the rotating disk 11, and the inner transmitting portion and the outer shielding portion constitute one bit. Eight light emitting elements 12a to 12h are arranged on one side at equal intervals in the radial direction with the rotating disk 11 interposed therebetween, and the same eight light receiving elements 13a to 13h are arranged on the other side with the light emitting elements 12a to 12h. It is arranged to face. The light emitting elements 12a to 12h are connected in parallel to an AC signal generating circuit 14, as shown in FIG.
h is connected to each of the output terminals a to h of the rotation angle signal generation circuit 1 via the amplifiers 15a to 15h. Then, the light receiving elements 13a, 13b and 13c, 13d and 13e, 13
f and 13g and 13h make a pair, respectively, and when one of them is shielded by the shielding part 11B and is in the non-light receiving state, the other is the transmission part 1
1A, the light receiving state is established, and each of these sets represents each bit of the binary code signal, and each bit is constituted by a binary signal of a two-wire system in which logical values 1 and 0 are dual.

Therefore, in the rotation angle signal generating circuit 1 of this embodiment, the angular position is represented by a 4-bit binary code signal of P1, P2, P3, P4, and each of the bits P1 to P4
Are P1 = (P11, P10) and P2 = (P21, P2) as binary signals of a two-wire system in which logical values 1 and 0 are dual.
20), P3 = (P31, P30), P4 = (P41,
P40), and output Pi1 and Pi0 (i = 1 to
4) is such that when one is shielded by the rotating disk 11 and has a logical value of 0, the other is not shielded and has a logical value of 1. Here, P11 and P10 are the outputs of the light receiving elements 13a and 13b,
P21 and P20 are outputs of the light receiving elements 13c and 13d, P3
1 and P30 are the outputs of the light receiving elements 13e and 13f, P41 and P40 are the outputs of the light receiving elements 13g and 13h. Therefore, the output from the output terminal a to the output of P11, the output from the output terminal b to the output of P10, P21 output from output terminal c, P20 output from output terminal d, P31 from output terminal e
Output, output terminal f to P30 output, output terminal g to P4
1 and the output P40 are generated from the output terminal h.

For example, the angle θ1 in FIG.
It is represented by a binary code signal of P2 = 1, P3 = 1, P4 = 1. At this time, P1 = (1,0), P2 = (1,
0), P3 = (1, 0), and P4 = (1, 0). Further, the angle of θ2 is P1 = 1, P2 = 1, P3 = 0, P
4 = 1, where P1 = (1, 0), P2 =
(1,0), P3 = (0,1), P4 = (1,0).

Next, the adder circuit 2 of this embodiment will be described with reference to FIG. In the figure, an adding circuit 2 includes a capacitor C _A1
To C _A4 , C _{B1 to} C _B4 and diodes D _{A1 to} D _A4 , D _{B1 to} D
It is composed of a voltage doubler rectifier circuit using _B4 . In the adding circuit 2, the input signal is clamped to _the power supply voltage V _cc by the diode D _A1 to D _A4 via the capacitor C _A1 -C _A4 inserted in series, further to the capacitor C _B1 -C _B4 respectively The input level is accumulated. Therefore,
The input signal levels stored in the capacitors C _{B1 to} C _B4 are sequentially stored and added by the AC signal input, and the added value is superimposed on the power supply voltage V _CC and output to the threshold calculation circuit 3 in the next stage.

The threshold value calculation circuit 3 shown in FIG. 1 is composed of a conventionally known fail-safe window comparator composed of a plurality of transistors and resistors and the like, and is used only when an input signal of a predetermined level is input to an input terminal. An output signal is generated (corresponding to a logical value of 1), and the AC output signal is stopped (corresponding to a logical value of 0) when a circuit fails.

Next, the operation of this embodiment will be described. For example, a case where the desired rotation angle to be detected on the rotation shaft 10 is θ2 in FIG. 3 will be described. In this case, the binary code signals are P1 = 1, P2 = 1, P3 = 0,
P4 = 1, and at this time, for P3 and P4, it is necessary to represent no light as a logical value 1. Therefore, the output terminals a, c, f, and g of the rotation angle signal generation circuit 1 are connected to the input terminals of the addition circuit 2 to output the outputs P11, P21, and P11.
30, and P41 are input.

The rotating disk 11 is synchronized with the rotation of the rotating shaft 10.
Is rotated, the light from each of the light emitting elements 12a to 12h is transmitted or cut off as the light passes through the transmitting part 11A and the shielding part 11B, and the light is output from the light receiving elements 13a to 13h arranged at the positions where the light is transmitted. Occurs. Therefore, the portion of the rotating disk 11 corresponding to θ2 in FIG.
2a to 12h and the light receiving elements 13a to 13h,
Light from the light emitting elements 12a, 12c, 12f, 12g passes through the transmitting portion 11A, and the light receiving elements 13a, 13c, 13f,
The light from the light emitting elements 12b, 12d, 12e, and 12h is received by the shielding unit 11g.
B, the light receiving elements 13b, 13d, 13e, 13
h and no output occurs. As a result, the corresponding light receiving elements 13a, 13a
AC outputs from c, 13f, 13g are applied, and the input of the adder circuit 2 is P11 = 1 (with light), P21 = 1 (with light), P30 = 1 (no light), P41 = 1 (with light) Are all logical values 1.

As described above, when all the inputs of the adding circuit 2 have the logical value 1, the added output becomes equal to or greater than the threshold value of the threshold value calculating circuit 3, and the threshold value calculating circuit 3 generates an AC output (corresponding to the logical value 1). Then, a desired detection angle signal is generated. Then, the output of the rotation angle signal generation circuit 1 is set to AC (this input signal is not generated at the time of input-side failure, so the added value is always smaller than the threshold value (3 or less in this embodiment)). By adopting a circuit configuration in which the output does not become a logical value 1 at the time of a fault, no AC output is generated at the time of a circuit fault, and the output of the threshold value operation circuit 3 is erroneous from the logical value 1 to the logical value 0 but erroneous to the logical value 1. And a fail-safe configuration that is not mistaken for danger.

As described above, a binary signal of a two-wire system is directly generated without performing a negation operation, and the absence of light is represented as a logical value 1, and all signals are generated by the addition circuit 2 and the threshold value operation circuit 3. By generating a desired angle signal while confirming that the rotary encoder is operating, it is possible to further enhance the fail-safe property of the rotary encoder. Next, a second embodiment of the rotary encoder according to the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the output of the rotation angle signal generating circuit is configured to be a four-wire system that generates 0-phase and π-phase signals of mutually opposite phases with respect to each of the two-wire binary signals. is there. In FIG. 6, 16a, 16a 'to 16h, 16
h ′ is a light emitting element that emits light based on the output of the corresponding light receiving element 13a to 13h, 17a, 17a ′ to
17h to 17h 'correspond to the corresponding light emitting elements 16a,
Light receiving elements for receiving light from 16a 'to 16h, 16h' and generating outputs, Tra, Tra 'to Trh, Tr
h 'is a transistor, and Ra, Ra' to Rh, and Rh 'are resistors. Output terminals a, a' to h, and h 'generate π-phase and zero-phase AC signals having mutually opposite phases.

For example, when the light from the light emitting element 12a is received by the light receiving element 12a via the transmitting portion 11A, an AC signal having a 180 ° phase difference from the output of the light emitting element 12a is generated from the output terminal a. Then, an AC signal having the same phase as the output of the light emitting element 12a is generated from the output terminal a '. Where P
The in-phase signals of i1 and Pi0 (i = 1 to 4) are
i00 (i = 1 to 4), and the antiphase signals are Pi1π, P
Indicated by i0π (i = 1 to 4).

The rotation angle signal generation time thus converted into four lines
When the path 1 'is used, the adding circuit 2' of this embodiment is
Capacitor C like 7_C1~ C_C4, C and diode D_C1
~ D _C4, D, and a voltage doubler rectifier circuit.
Can be simplified. And in this case, next to each other
A signal of opposite phase is applied to the input terminal. Take
In the adder circuit 2 'shown in FIG.
When force signals are applied, adjacent input signals
It is out of phase, and its output is generated when the input level of each input terminal is inverted.
At the input end, the sum of the input levels is equal to the power supply voltage V_CCSuperimposed on
Output occurs.

In this embodiment, for example, as in the first embodiment, when the desired rotation angle to be detected on the rotating shaft 10 is θ2 in FIG. 3, the output terminal of the rotation angle signal generation circuit 1 'and the addition circuit 2' The connection of the input terminal is as follows.
The output terminals a, c ', f, and g' of the rotation angle signal generation circuit 1 'are connected to the respective input terminals of the addition circuit 2', and the output P
11π, P210, P30π, and P410 are input so that the input signals of the input terminals adjacent to each other of the adder circuit 2 ′ have opposite phases. Note that the inputs to the adder circuit may be connected so as to be P110, P21π, P300, and P41π.

In this manner, the rotating disk 11 rotates in synchronization with the rotation of the rotating shaft 10, and the light emitting elements 12a, 12a, 12
When light from c, 12f, and 12g is received by the light receiving elements 13a, 13c, 13f, and 13g via the transmission portion 11A and an output is generated, the corresponding light receiving element 13a, AC outputs of opposite phases from 13c, 13f and 13g are applied, and the input values are added in an adding circuit 2 '. The added output becomes equal to or larger than the threshold value of the threshold value calculating circuit 3, and an AC output is generated from the threshold value calculating circuit 3. (Logical value 1
), And a desired detection angle signal is generated.

Also in the case of the second embodiment, as in the first embodiment, a binary signal of a two-wire system is directly generated without performing a negation operation, and all signals are generated by the addition circuit 2 'and the threshold value operation circuit 3. After confirming that the signal is generated, a desired angle signal is generated, and the fail-safe property of the rotary encoder can be further improved. 8 and 9 show other examples of the rotation angle signal generation circuit.

FIG. 8 shows a light emitting element 12b, 12d, 12f, 12h and a light receiving element 13b,
The relationship with 13d, 13f, and 13h is not a transmission type but a reflection type. That is, the light receiving elements 13b, 13d, 13
f, 13h to the light emitting elements 12b, 12d, 12f, 12
h, the shielding part 11B of the rotating disk 11 '.
The light receiving elements 13b, 13b are reflected by light when
In this configuration, a logical value 1 is generated from d, 13f, and 13h. In FIG. 8, the light emitting elements 12a,
Only 12b and light receiving elements 13a and 13b are shown, and other light emitting elements and light receiving elements are not shown. In this case, the rotating disk 11 'does not require the shielding portion 11B that pairs with the transmitting portion 11A in the radial direction. For example, at an angle of θ1, all become the transmissive portion 11A, and the light emitting elements 12a, 12a
The light from c, 12e, and 12g is received by the light receiving elements 13a, 13c, 13e, and 13g via the transmitting portion 11A, while the light from the light emitting elements 12b, 12d, 12f, and 12h is
The light passes through the rotating disk 11 'through the transmitting portion 11A and is not received by the light receiving elements 13b, 13d, 13f, and 13h. As described above, even when the transmission type and the reflection type photodetectors are used, a fail-safe binary signal of a two-wire system can be obtained.

FIG. 9 shows an example in which the light emitting element of the reflection type light detecting device in FIG. 8 is also used as the light emitting element of the transmission type light detecting device to simplify the configuration. By doing so, the light emitting elements 12b, 12d, 12
f and 12h can be omitted, and the light emitting element can be reduced by half.

[0031]

As described above, according to the present invention, the output signal of the rotation angle signal generating means is directly converted into a two-wire system signal in which logical values 1 and 0 are dual with each other without performing a negation operation. Is output as a logical value 1, and the necessary signals of the binary code signal corresponding to the desired detection angle are added and the threshold value is calculated, thereby confirming that all the signals are generated, and checking the desired angle. Since the detection output is generated, the fail-safe property of the rotary encoder can be further improved. Therefore, safety in a control system that requires an angle signal using a rotary encoder can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a rotation angle signal generation circuit according to the first embodiment;

FIG. 3 is a detailed view of the rotating disk of FIG. 2;

FIG. 4 is a circuit diagram of a rotation angle signal generation circuit according to the first embodiment;

FIG. 5 is a circuit diagram of an adding circuit according to the first embodiment;

FIG. 6 is a circuit diagram of a rotation angle signal generation circuit according to a second embodiment of the present invention.

FIG. 7 is a circuit diagram of an addition circuit suitable for the second embodiment;

FIG. 8 is a schematic configuration diagram of a rotation angle signal generation circuit according to a third embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a rotation angle signal generation circuit according to a fourth embodiment of the present invention.

[Explanation of symbols]

1, 1 'rotation angle signal generation circuit 2, 2' addition circuit 3 threshold value calculation circuit 10 rotation axis 11, 11 'rotation disk 12a to 12h, 16a, 16a' to 16h, 16h '
Light-emitting elements 13a to 13h, 17a, 17a 'to 17h, 17h'
Light receiving element

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01D 5/00-5/62

Claims (2)

(57) [Claims] 1. A rotary encoder for detecting a rotational position of a rotating body, comprising: a rotating disk having a signal transmitting portion and a signal shielding portion formed in a predetermined pattern and rotating in synchronization with the rotating body; Signal generating means for generating an AC output having a logical value of 1 when a signal is received and a logical value of 0 when no signal is received by passing the signal transmitting portion and the signal shielding portion with rotation of the disk, and rotating the rotating disk. Accordingly, a binary code signal of a predetermined number of bits is generated from the signal generating means, wherein each bit is a binary signal having two logical values of 1 and 0, respectively. Rotation angle signal generating means for performing the operation, addition operation means for performing an addition operation on the output logical value of the binary code signal of the rotation angle signal generation means corresponding to a desired detected angular position, and addition operation value of the addition operation means being preset. Rotary encoder at the time generates an output of logic value 1 failure when and above threshold was characterized by being configured with a threshold value calculating means as the output of logic value 0. 2. A rotary encoder according to claim 1, wherein the signal generation means of said rotation angle signal generation means has a four-wire system configuration for generating an anti-phase signal for each of the two-wire system signals. .