JP5043639B2 - Rotary encoder - Google Patents

Description

  The present invention relates to an absolute type or incremental type rotary encoder, and more particularly to a rotary encoder capable of monitoring the state of the rotary encoder and transmitting the monitoring result to a host device of the rotary encoder.

  For example, an incremental type rotary encoder RE will be described with reference to FIG. 7 and the subsequent drawings. FIG. 7 shows a mechanical configuration of the rotary encoder RE, FIG. 8 shows an electrical configuration of the rotary encoder RE, and FIG. The signal waveform of a phase signal and a B phase signal is shown.

  Referring to FIG. 7, the rotary encoder RE includes light from the light projecting element LED at equal intervals in the circumferential direction between the light projecting element LED and a plurality (two in this example) of light receiving elements PDa and PDb. A rotary slit plate RS having a plurality of slits (hereinafter referred to as “rotary slits”), and light from the light projecting element LED can be transmitted to one side of the rotary slit plate RS in the same manner as the slits. A fixed slit plate FS having a slit (hereinafter referred to as “fixed slit”) that can be formed is disposed oppositely.

  The fixed slit of the fixed slit plate FS shifts the light from the light projecting element LED by 90 degrees sequentially in electrical angle and passes through the rotary slit of the rotary slit plate RS to form an optical signal. The optical signals are received as the detection circuit 105 by the light receiving elements PDa and PDb.

  Referring to FIG. 8, the outputs of the light receiving elements PDa and PDb are compared with the reference value (ref) by the A-phase and B-phase determination circuits 106 and 108 including the comparators CPa and CPb, respectively. Pulse signals (A-phase and B-phase signals) as shown in (b) are generated, and the A-phase and B-phase signals are output from the A-phase and B-phase output circuits 107 and 109, respectively. .

  When the rotary encoder RE having the above configuration is incorporated into, for example, an electronic control system that electronically controls an elevator, the rotary encoder RE is attached to the rotary shaft of a drive motor that drives the car to move up and down, and the rotary encoder RE The A-phase and B-phase signals are input to the electronic control device that is the host device. The electronic control device drives and controls the drive motor by the A-phase and B-phase signals from the rotary encoder RE to control the raising / lowering of the car (for example, see Patent Document 1). In this electronic control system, the safety of the electronic control system is mainly achieved by the control operation of the control CPU incorporated in the electronic control device. The control CPU controls various loads in response to control programs, various control constants, and operating states of various input sensors.

  In the above configuration, it is conceivable that the electronic control device side additionally includes a determination program for performing a fixed determination on the abnormal state on the rotary encoder RE side based on the presence / absence of the A-phase and B-phase signals, the signal waveform, and the like. However, the additional installation of such a determination program and the execution of the determination program increase the burden on the control CPU and cause a delay in electronic control speed and an increase in cost. Moreover, it is difficult for the elevator manufacturing side and the encoder manufacturing side to be separated, and for the elevator manufacturing side to add the determination program or the like unless the details of the rotary encoder RE are clear. Moreover, in an elevator apparatus that has already been installed in a building or the like, in most cases, it may be left unattended.

  Under such circumstances, the rotary encoder RE side constantly monitors its state so that the rotary encoder RE does not suddenly become abnormal, and immediately notifies the monitoring state to the electronic control unit, which is the host device. It is desirable that the electronic control side can perform a required response quickly.

  Accordingly, the present applicant sets a large number of items for monitoring the state of the rotary encoder RE while incorporating the monitoring CPU in the rotary encoder RE, and causes the monitoring CPU to capture monitoring signals for each item. It is considered that the processing result of the rotary encoder RE monitoring is transmitted by the CPU to the control CPU of the electronic control device which is the host device.

  The above monitoring items include the state of the main power supply, the state of the light emitting element, the state of the light receiving element, the state of the internal circuit such as the output circuit of the A phase and B phase signals, and the A phase and B phase signals that are external outputs. There are many pulse signal states. In this case, the monitoring CPU attempts to monitor the internal circuit abnormality at the internal interrupt timing, and to monitor the pulse signal abnormality at the external interrupt timing (pulse signal change timing). In the case of high-speed rotation, the internal interrupt is affected by the priority of the external interrupt, and the monitoring error becomes large, which affects the safety and stability of the entire electronic control system incorporating the rotary encoder RE. Will come.

  Therefore, in order to fully utilize the control capability of the monitoring CPU, the applicant of the present invention monitors the monitoring items by the monitoring CPU in an abnormal state of the internal circuit in the stop mode in which the rotary encoder RE is stopped. In the rotation mode, which is the mode in which the rotary encoder RE is rotating, it is considered that the monitoring items are divided into the stop mode and the rotation mode, such as monitoring the abnormality of the pulse signal.

On the other hand, in the case of a rotary encoder, in order to avoid the burden on the monitoring CPU, among the above-described pulse signals such as the A phase signal and the B phase signal, for example, the A phase signal is used for rotational speed detection. Will not change in rising or falling due to some abnormality, and if it is fixed at high level or fixed at low level, external interrupts will not occur due to changes in rising or falling of B phase signal, and abnormality detection of the B phase signal will be detected become unable.
Japanese Patent Application Laid-Open No. 09-077412

  Therefore, in the present invention, when a monitoring CPU is mounted on the rotary encoder and the state of the rotary encoder is monitored, the burden on the monitoring CPU can be reduced, so that the safety of the entire electronic control system described above can be reduced. Improvement of stability and stability is a problem to be solved.

A rotary encoder according to the present invention is a rotary encoder that generates a plurality of pulse signals having different electrical angles in accordance with rotation of a detected shaft and outputs the pulse signals to a host device. The rotary encoder includes a light projecting element and the light projecting element. and the oppositely disposed a plurality of light receiving elements, a circumferential plurality of rotary slits are arranged to rotate synchronously with the sensed shaft between the light projecting element and the light receiving elements, for the plurality of rotary slits passage of light projected from the light projecting element, from the output of the light receiving elements corresponding to the cut-off and an output circuit for generating and outputting a plurality of pulse signals used for the detection of the rotation state of the rotary encoder, the internal the rotary encoder includes a monitoring CPU for monitoring the state at different monitoring item in the stop mode and the rotary mode, the said monitoring CPU is based on the pulse signals A judgment the rotary encoder of whether the non-rotating state rotation state, the determination that said non-rotating state and stop mode, the determination of the rotational state, performs a duty operation in different revolution to the respective pulse signals If the calculated result is abnormal, a fail output is output to the host device, and if the result is normal, the next pulse signal is determined.

  The pulse signal is not limited to the A phase signal and the B phase signal described in the embodiment, and can include a plurality of signals.

  Further, the duty calculation and the like are performed at a different rotation speed for each pulse signal. Therefore, for example, if the pulse signal is an A phase signal, a B phase signal, a -A phase signal, and a -B phase signal, the first rotation is the A phase signal, the second rotation is the B phase signal, and the third rotation is the -A phase. For example, a duty calculation of a different pulse signal is performed for each rotation, such as a -B phase signal for the fourth rotation and an A phase signal for the fifth rotation.

  In the present invention, since the monitoring CPU for monitoring the state of the rotary encoder is built in, the monitoring CPU monitors the state inside the rotary encoder using different monitoring items in the stop mode and the rotation mode. As a result, the processing load on the monitoring CPU in the rotation mode can be greatly reduced, and as a result, the state of the rotary encoder is immediately transmitted to the electronic control device, which is the host device, so that the required response can be quickly performed on the electronic control device side. As a result, the safety and stability of the entire electronic control system incorporating the rotary encoder can be improved.

In the present invention, the monitoring CPU determines whether the rotary encoder is non-rotating or rotating based on each pulse signal, sets the non-rotating determination to the stop mode, and determines whether the rotary encoder is rotating. The duty of the pulse signal is calculated for each rotation, and if the calculated duty is abnormal, the fail output is output to the host device, and if it is normal, the next pulse signal is determined. Will be able to reduce the burden on the abnormality monitoring in the rotation mode.

  As described above, in the present invention, the abnormality of the pulse signal can be immediately transmitted to the electronic control device, which is the host device, by fail output so that the required response can be quickly performed on the electronic control device side. Can contribute to the improvement of the safety and stability of the entire electronic control system.

  In the present invention, when the monitoring CPU is mounted on the rotary encoder and the state of the rotary encoder is monitored, the burden on the monitoring CPU can be reduced, so that the safety and stability of the entire electronic control system described above can be reduced. It is possible to improve the performance.

  Hereinafter, a rotary encoder according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a circuit block configuration of the rotary encoder RE of the embodiment, and FIG. 2 shows an electrical hardware configuration of the rotary encoder RE. In these drawings, reference numeral 101 denotes a power supply circuit that receives supply of power from the external terminals Vcc and 0 V and generates the internal power supply 104 of the rotary encoder RE. Reference numeral 102 denotes a power supply voltage monitoring circuit that monitors the power supply of the power supply circuit 101. Is a light projecting element driving circuit for driving the light projecting element LED with power from the power supply circuit 101, and 105 is a detection circuit including the light receiving elements PDa and PDb. The detection circuit 105 outputs a-phase, b-phase, and ref-phase signals. The a phase signal is the output of the light receiving element PDa, the b phase signal is the output of the light receiving element PDb, and the ref phase signal is the reference signal. Reference numeral 106 denotes a comparator CPa, which compares the a-phase signal with the ref-phase signal to determine H or L of the A-phase signal, and 107 denotes an output A of the A-phase determination circuit 106. The phase output circuit 108 includes a comparator CPb, and compares the b-phase signal with the ref-phase signal to determine H or L of the B-phase signal. 109 denotes the B-phase determination circuit 108. A phase B output circuit 110 for outputting an output is a light receiving element operation determination circuit for determining the operation of the light receiving elements PDa and PDb from the output of the detection circuit 105.

  Reference numeral 111 denotes a monitoring CPU. A power supply voltage monitoring signal (1) from the power supply voltage monitoring circuit 102 and a drive circuit monitoring signal (2) for the light emitting element LED are connected to the AD conversion port A / D of the monitoring CPU 111. The a-phase signal (3) of the light-receiving element PDa, the b-phase signal (4) of the light-receiving element PDb, and the ref-phase signal (5) are input, and the A-phase signal determination signal (6) is input to the general-purpose port I / O. , A determination signal (7) for the B phase signal is input, and the output signal OUT A (8) of the A phase output circuit 107 and the output signal OUT B (9) of the B phase output circuit 109 are input to the interrupt port INT. Is done.

  The monitoring CPU 111 monitors the rotary encoder RE according to the monitoring item table shown in FIG. In this monitoring item table, the monitoring items of the rotary encoder RE are roughly divided into internal circuit monitoring and pulse signal monitoring. The monitoring items of the internal circuit are further divided into power supply voltage abnormality, light emitting element current abnormality, light receiving element output abnormality, and output circuit abnormality, and pulse signal monitoring is further divided into duty abnormality and high speed abnormality.

  In the internal circuit monitoring, the light emitting element LED makes a determination based on a voltage monitoring signal (2) of a constant current circuit (not shown), and the light receiving element uses a signal (3)-(5) from the light receiving element operation determining circuit 110, for example, It is determined whether or not the power supply common terminal CT of the light receiving elements PDa and PDb is connected, whether or not the wire bonding of the light receiving elements PDa and PDb is cut, an initial failure of the light projecting element LED, and the like. In the output circuit, the determination is made by comparing the determination signals (6) and (7) of the respective phase determination circuits 106 and 108 with the output signals (8) and (9) of the output circuits 107 and 109.

  In the pulse signal monitoring, when the rotary slit plate RS is rotating, the output period of the A phase signal and the B phase signal is counted, and the normality and abnormality of the duty of the A phase signal and the B phase signal are determined from the count result. To do. In this duty abnormality, the determination is made based on whether the duty of the A-phase signal and the B-phase signal is within a specified range. Moreover, when the rotation operation (high-speed rotation) more than expected is performed from the count result, it is determined as a high-speed abnormality.

  As described above, the monitoring CPU 111 monitors the stop mode (marked with a circle in the table of FIG. 3) for monitoring the internal circuit, and monitors the rotation mode (marked with a x in the table of FIG. 3) for monitoring the pulse signal. Then, in the stop mode, the monitoring CPU 111 switches to the monitoring item of the internal circuit and performs control to notify the electronic control device 207 which is the host device of the monitoring result of whether the internal circuit is normal or abnormal. Control is performed to switch to the monitoring item of whether or not the signal is normally output and to notify the electronic control unit 207 of the monitoring result of whether the pulse signal is normal or abnormal. In this case, the monitoring CPU 111 outputs the monitoring result as, for example, a fail signal to the electronic control unit 207 via the fail (FAIL) output circuit 112.

  An electronic control system incorporating the rotary encoder RE of the embodiment will be described with reference to FIG. This electronic control system is a system for controlling an elevator apparatus. The elevator apparatus 201 drives a hoisting machine 202 by a driving motor 203 to raise and lower a passenger car 205 via a rope 204, while using a detected shaft. A and B phase signals, which are detection signals from the rotary encoder RE of the embodiment attached to the rotating shaft 206 of a certain driving motor 203, are input to the electronic control unit 207. The electronic control unit 207 has a built-in control CPU, and drives and controls the drive motor 203 by A and B phase signals that are detection signals from the rotary encoder RE. The electronic control unit 207 includes a control CPU 208 and can process the A and B phase signals from the rotary encoder RE and the fail output from the fail (FAIL) output circuit 112.

  In the case of the rotary encoder RE according to the embodiment, in the stop mode, the monitoring CPU 111 receives the signals (6) and (7) taken into the general-purpose port I / O and the signals (1) taken into the AD conversion port A / D. )-(5), the normality / abnormality determination processing according to the table of FIG. 3 is performed and the determination result is transmitted to the electronic control unit 207. On the other hand, in the rotation mode, the signals (8) (9) fetched to the external interrupt terminal INT ), Normality / abnormality determination processing according to the table of FIG. 3 is performed, and the determination result is transmitted to the electronic control unit 207.

  Next, the internal interrupt in the stop mode will be described with reference to FIG. 5. In the stop mode, the monitoring CPU 111 monitors the power supply voltage and the light emitting element shown in the table of FIG. Performs AD conversion for (LED) voltage monitoring, reference voltage (PDref) monitoring, light receiving element (PDa) voltage monitoring, light receiving element (PDb) voltage monitoring, etc. and stores the AD conversion value, and the timer output is low level When the signal goes to the high level, the most recent AD conversion value (◯ mark) is taken in. While repeating this a predetermined number of times, the average value thereof is calculated, and the calculated average value is compared with the determination value to determine the abnormal state. The period during which the timer is at a high level is the processing time for these determinations.

  In the rotation mode, the monitoring CPU 111 performs monitoring processing for the monitoring items shown in the table of FIG.

  As described above, in the embodiment, the monitoring item of the rotary encoder RE is a monitoring item (internal circuit monitoring in FIG. 3) that performs signal processing with an internal interrupt in the stop mode, and an item that performs signal processing with an external interrupt in the rotation mode (see FIG. In the rotation mode, the monitoring item by the internal interrupt can be performed without being influenced by the external interrupt.

  Next, the monitoring operation of the monitoring CPU 111 of the rotary encoder RE according to the embodiment will be described with reference to FIG. The execution actor of each of the following steps n1-n11 is the monitoring CPU 111.

  First, when the power is turned on, in the first step n1, it is determined whether the rotary encoder RE is non-rotating or rotating based on the A-phase signal. Whether the rotary encoder RE is non-rotating or rotating is determined based on the period calculation value of the A-phase signal. That is, the bit counter counts, for example, one period from the rising edge to the next rising edge of the A phase signal. Whether the rotary encoder RE is non-rotating or rotating is determined based on whether the count value in one cycle of the A-phase signal is greater than or less than a predetermined value. The non-rotation or the rotation in this case is determined by the monitoring CPU 111 and does not mean the state in which the rotary encoder RE is physically rotating. The monitoring CPU 111 is in the stop mode and the rotation mode. This is a determination to be used as a reference when monitoring the set monitoring item. In addition, since the period calculation using such a counter is known, description is abbreviate | omitted.

  When it is determined in the first step n1 that the rotary encoder RE is in the stop mode, the monitoring items defined in the table of FIG. 3 are monitored in the second step n2. On the other hand, when it is determined in the first step that the rotary encoder RE is in the rotation mode, the duty of the A-phase signal is calculated in the first rotation of the rotary encoder RE in the third step n3. The fourth step is to determine whether the calculated duty of the A-phase signal is outside the predetermined range (abnormal range of 30% or less or 70% or more) or within the predetermined range (normal range of more than 30% and less than 70%). n4. The A phase signal is paired with the B phase signal, and the outputs of the light receiving elements PDa and PDb according to the passage and blocking of the light projection from the light projecting element LED with respect to the rotary slit are compared with the reference level ref by the comparison circuits CPa and CPb. This is obtained by comparison, and is used to detect the rotational state of the rotary encoder RE. The duty of the A-phase and B-phase signals is usually set to 50%. When this duty is outside the predetermined range, it can be considered that the outputs of the light receiving elements PDa and PDb are abnormal. In addition, the said predetermined range is an example and is not limited to this. The same applies to the following.

  Therefore, in the fourth step n4, it is determined whether the calculated duty is within the predetermined range or outside the predetermined range. If the determination in the fourth step n4 is out of the predetermined range, the fail output is increased in the fifth step n5. Process to output to the device. On the other hand, if the determination at the fourth step n4 is within the predetermined range, the sixth step n6 determines whether the rotary encoder is non-rotating or rotating based on the B-phase signal. If the determination in the sixth step n6 is non-rotation, monitoring in the stop mode is performed in the seventh step n7. If the determination in the sixth step n6 is rotation, the rotary encoder is detected in the eighth step n8. The duty of the B phase signal is calculated at the second rotation of RE. The purpose of calculating the duty of the B phase signal is the same as that for the A phase signal. In the ninth step n9, whether the duty calculated in the eighth step n8 is out of the predetermined range (30% or less or an abnormal range of 70% or more) or within the predetermined range (normal range of more than 30% and less than 70%). Judgment is made.

  Next, if the determination at the ninth step n9 is outside the predetermined range, a process of outputting a fail output to the electronic control unit 207 is performed at the tenth step n10, and the determination at the ninth step n9 is within the predetermined range. If there is, the process returns to the determination of the A phase signal in the eleventh step n11.

  As described above, in the embodiment, the built-in monitoring CPU 111 determines the rotation state based on the A-phase signal. If this determination is non-rotation, the internal circuit that is a monitoring item at the time of rotation stop is monitored as the stop mode, and when determining the rotation mode, it is determined whether the duty of the A-phase signal is outside the predetermined range or not. Do. If the duty of the A phase signal is outside the predetermined range, a process of outputting a fail output to the electronic control unit 207 is performed.

  If the duty of the A-phase signal is within a predetermined range, the rotational state is then determined based on the B-phase signal. If this determination is non-rotation, the stop mode is set, and if it is rotation, the same operation as the A-phase signal is performed for the B-phase signal.

  In this way, in the embodiment, the state of the rotary encoder RE can be transmitted to the electronic control device 207 so that the electronic control device 207 can quickly perform the required response, and the electronic control system incorporating the rotary encoder RE. It can contribute to the improvement of overall safety and stability.

FIG. 1 is a diagram showing a schematic configuration of a rotary encoder according to an embodiment of the present invention. FIG. 2 shows the electrical configuration of the rotary encoder. FIG. 3 is a table showing monitoring items by the monitoring CPU. FIG. 4 is a diagram showing a configuration of an electronic control system in which the rotary encoder of the embodiment is incorporated. FIG. 5 is a diagram showing the monitoring timing by an internal interrupt in the rotary encoder stop mode. FIG. 6 is a flowchart for explaining the operation of the rotary encoder according to the embodiment. FIG. 7 is a diagram showing a general configuration of a rotary encoder. FIG. 8 is a diagram showing an electrical configuration of a conventional rotary encoder. FIG. 9 is a diagram showing signal waveforms of A-phase and B-phase signals.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Power supply circuit 102 Power supply voltage monitoring circuit 103 Emitting element drive circuit 104 Internal power supply 105 Detection circuit 106 A phase determination circuit 107 A phase output circuit 108 B phase determination circuit 109 B phase output circuit 111 Monitoring CPU
201 Elevator device 203 Motor 207 for driving Electronic control device (host device)

Claims (1)

A rotary encoder that generates a plurality of pulse signals having different electrical angles with rotation of a detected shaft and outputs them to a host device,
The rotary encoder is
A light emitting element;
A plurality of light receiving elements arranged opposite to the light projecting elements;
A circumferential plurality of rotary slits are arranged to rotate synchronously with the sensed shaft between the light projecting element and the light receiving elements,
Passage of light projected from the light projecting element with respect to said plurality of rotary slits, and an output circuit for generating and outputting a plurality of pulse signals used from the outputs of the respective light receiving elements corresponding to the cut-off to the detection of the rotation state of the rotary encoder ,
A monitoring CPU for monitoring the internal state of the rotary encoder with different monitoring items in the stop mode and the rotation mode;
With
The monitoring CPU is
A judgment the rotary encoder is either non-rotating state or rotating state based on the pulse signals, the determination of the non-rotating state and the stop mode, the determination of the rotational state, with respect to each pulse signal performs duty operation at different revolution, if the calculated result is abnormal, and outputs a fail output to the host device, a rotary which the result is adapted to perform the determination of the next pulse signal if normal Encoder.

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