Encoder with overvoltage damage prevention circuit

Abstract

An encoder comprises: an encoder main circuit, which is driven by an encoder main circuit driving voltage supplied from at least one internal power supply and generates rotation information of a rotating body; an overvoltage damage prevention circuit, which generates an abnormality detection unit driving voltage based on the voltage supplied from the main power supply; an abnormality detection unit, which is driven by the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit and detects abnormalities related to the internal power supply; and a blocking circuit, which blocks the internal power supply from supplying the encoder main circuit driving voltage to the encoder main circuit when the abnormality detection unit detects an abnormality.

Description

Technical Field

[0001] The present invention relates to an encoder having an overvoltage damage prevention circuit. Background Art

[0002] Encoders are used to detect the rotation information of rotating bodies such as the rotating shaft of a motor provided in a machine tool, a robot, etc., the movable part of a robot, etc. An encoder is used. Power is supplied from a plurality of power supplies to a main circuit in the encoder (hereinafter referred to as an "encoder main circuit"). For example, as an electronic component constituting the encoder main circuit, there is a memory for maintaining position information, origin information, etc. of detected motors and rotating shafts. In order to maintain the information stored in the memory, power is supplied from the main power supply. In addition, when the operation of a machine tool, a robot, etc. provided with an encoder ends or when a power outage occurs, if the power supply from the main power supply to the encoder is cut off, the information stored in the memory in the encoder will be lost, and therefore, power is supplied from a backup power supply.

[0003] For example, an absolute encoder is known, which has a backup power supply. When the power supply from the main power supply is blocked, the position information of the detected object is detected and maintained by the power supplied from the backup power supply. The absolute encoder is characterized in that the absolute encoder also has: a voltage regulator, which adjusts the output voltage from the backup power supply to a predetermined voltage; and a voltage abnormality information holding device, which operates at the predetermined voltage. The voltage abnormality information holding device monitors the output voltage of the backup power supply during the period when the main power supply is disconnected, and when it is detected that the output voltage of the backup power supply deviates from a predetermined range, the voltage abnormality information is stored as voltage abnormality information, and when the main power supply is turned on, the stored voltage abnormality information is output to the outside (for example, refer to patent document 1).

[0004] For example, a backup power supply for an absolute encoder is known, which supplies power to the absolute encoder when the power supply of a control device that controls a controlled device is disconnected so that the absolute encoder can perform at least one of position detection and position information retention of the controlled device. The backup power supply comprises: a secondary battery, a charging circuit for charging the secondary battery, a backup battery, and a power switching circuit, wherein the power switching circuit selects the output of the secondary battery and outputs it to the absolute encoder when the output voltage of the secondary battery is above a specified value, and selects the output of the backup battery and outputs it to the absolute encoder when the output voltage of the secondary battery is lower than a specified value (for example, refer to patent document 2).

[0005] For example, there is known a backup power supply for an absolute encoder having an abnormality detection function for at least one of a secondary battery and a charging circuit. When the power supply of a control device that controls a controlled device is disconnected, power is supplied to the absolute encoder so that the absolute encoder can perform at least one of position detection and position information retention of the controlled device. The backup power supply is characterized in that the backup power supply has: a secondary battery, a charging circuit that charges the secondary battery, and an abnormal state detection circuit that detects an abnormal state of at least one of the secondary battery and the charging circuit. When the abnormal state detection circuit detects an abnormality in at least one of the secondary battery and the charging circuit, the output voltage of the backup power supply is changed to a voltage at which the absolute encoder detects an abnormal state of the backup voltage (for example, refer to patent document 3).

[0006] For example, an encoder having a backup power supply device is known, which supplies power to the encoder when the main power supply of the encoder is disconnected, and is characterized in that the backup power supply device has a dual-system battery consisting of a main battery and a sub-battery, and after the power supply of the encoder is switched from the main power supply to the backup power supply device, power is supplied to the encoder from the main battery, and when the voltage level of the main battery drops to a specified voltage level requiring battery switching, the battery supplying power to the encoder is switched from the main battery to the sub-battery (for example, refer to patent document 4).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2008-216115

[0010] Patent Document 2: Japanese Patent Application Publication No. 2007-292608

[0011] Patent Document 3: Japanese Patent Application Publication No. 2007-288970

[0012] Patent Document 4: Japanese Patent Application Publication No. 2010-002267 Summary of the invention

[0013] Problems to be solved by the invention

[0014] In an encoder driven by receiving power supply from multiple power supplies, when power supplies with different output voltages are short-circuited, an overvoltage may be supplied to the encoder main circuit, causing the electronic components constituting the encoder main circuit to be damaged. In order to prevent such damage to the encoder main circuit, several power supplies among the multiple power supplies are used as monitored power supplies, and their output voltages are always monitored by an abnormal detection circuit. When an abnormal voltage is detected, the power supply from the monitored power supply is blocked by a blocking circuit. When an abnormality occurs, the power supply from the monitored power supply is blocked, so that the abnormal detection circuit receives power supply from a system different from the monitored power supply, i.e., the main power supply, to operate. However, when a short circuit occurs between the power supply supplying power to the abnormal detection circuit and the monitored power supply, an overvoltage is also supplied to the encoder main circuit, causing damage to the electronic components constituting the encoder main circuit. In this way, in an encoder driven by receiving power supply from multiple power supplies, there is a problem that it is difficult to prevent the damage of the encoder main circuit caused by power supply abnormalities including short circuits. Therefore, in an encoder driven by receiving power supply from multiple power supplies, it is desired to have a technology that can reliably prevent the damage of the encoder main circuit caused by overvoltage caused by power supply abnormalities.

[0015] Means for solving problems

[0016] According to one embodiment of the present disclosure, an encoder comprises: at least one internal power supply, which generates and outputs a voltage for driving an encoder main circuit; an encoder main circuit, which is driven using the encoder main circuit driving voltage supplied from the internal power supply and generates rotation information of a rotating body; an overvoltage damage prevention circuit, which generates and outputs a voltage for driving an abnormality detection unit based on the voltage supplied from the main power supply; an abnormality detection unit, which is driven using the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit and detects abnormalities related to the internal power supply; and a blocking circuit, which blocks the internal power supply from supplying the encoder main circuit driving voltage to the encoder main circuit when the abnormality detection unit detects an abnormality.

[0017] Effects of the Invention

[0018] According to one aspect of the present disclosure, in an encoder that is driven by receiving power supplied from a plurality of power supplies, it is possible to reliably prevent a main circuit of the encoder from being destroyed by an overvoltage due to power supply abnormality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a diagram showing an encoder according to the first embodiment of the present disclosure.

[0020] Figure 2 It is a diagram showing an encoder according to a second embodiment of the present disclosure.

[0021] Figure 3It is a diagram showing a specific example of a short-circuit detection unit and an overvoltage damage prevention circuit in an encoder according to the second embodiment of the present disclosure.

[0022] Figure 4 Yes means Figure 3 The flowchart shows the operation flow of the short circuit detection unit and the overvoltage damage prevention circuit in the encoder.

[0023] Figure 5 It is a diagram showing an encoder according to a third embodiment of the present disclosure.

[0024] Figure 6 It is a diagram showing a specific example of a short-circuit detection unit and an overvoltage damage prevention circuit in an encoder according to a third embodiment of the present disclosure.

[0025] Figure 7 Yes means Figure 6 The flowchart shows the operation flow of the short circuit detection unit and the overvoltage damage prevention circuit in the encoder. DETAILED DESCRIPTION

[0026] Hereinafter, an encoder having an overvoltage damage prevention circuit will be described with reference to the accompanying drawings. In each of the accompanying drawings, the same reference numerals are used to mark the same components. In addition, the scales of these drawings are appropriately changed for easy understanding. In addition, the method shown in the accompanying drawings is an example for implementation and is not limited to the method shown in the drawings.

[0027] The encoder of the embodiment of the present disclosure is installed on a rotating body such as a rotating shaft of a motor provided in a machine tool, a robot, etc., or a movable part of a robot, to generate rotation information such as the rotation position and rotation speed of the rotating body. The encoder of the embodiment of the present disclosure may be an optical type or a magnetic type. The encoder of the embodiment of the present disclosure is driven by the current supplied by the power supply, and the power supply that outputs the current for driving the encoder includes a main power supply and an internal power supply.

[0028] The encoder of the embodiment of the present disclosure has: at least one internal power supply, which generates and outputs the encoder main circuit driving voltage; the encoder main circuit, which is driven by the encoder main circuit driving voltage supplied from the internal power supply and generates the rotation information of the rotating body; the overvoltage damage prevention circuit, which generates and outputs the abnormality detection unit driving voltage according to the voltage supplied from the main power supply; the abnormality detection unit, which is driven by the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit and detects the abnormality related to the internal power supply; and the blocking circuit, when the abnormality detection unit detects the abnormality, the blocking circuit blocks the internal power supply from supplying the encoder main circuit driving voltage to the encoder main circuit. The embodiments of the present disclosure are listed below.

[0029] First, refer to Figure 1An encoder according to a first embodiment of the present disclosure will be described.

[0030] Figure 1 It is a diagram showing an encoder according to the first embodiment of the present disclosure.

[0031] The encoder 1 according to the first embodiment of the present disclosure includes a main power supply 10 , an internal power supply 11 , an encoder main circuit 12 , an overvoltage damage prevention circuit 13 , an abnormality detection unit 14 , and a blocking circuit 15 .

[0032] The main power supply 10 is, for example, a power supply that supplies power from the outside via an external connection terminal provided to the encoder 1. Alternatively, the main power supply 10 may be a primary battery or a secondary battery provided inside the encoder 1. When the main power supply is a primary battery or a secondary battery, the main power supply is treated differently from the internal power supply composed of the primary battery or the secondary battery. The voltage output by the main power supply 10 is, for example, 5 [V].

[0033] The internal power supply 11 generates and outputs a voltage for driving the encoder main circuit. The internal power supply 11 supplies power to the encoder main circuit 12 through a system different from the main power supply 10, and is composed of, for example, a primary battery, a secondary battery, a power supply that supplies power from the outside via an external connection terminal provided to the encoder 1, or a voltage regulator that generates a constant voltage based on the voltage supplied from the main power supply 10. The encoder main circuit driving voltage output by the internal power supply 11 is, for example, 3.3 [V], 1.5 [V], or 1 [V].

[0034] The encoder main circuit 12 is driven by the encoder main circuit driving voltage supplied from the internal power supply 11 to generate the rotation information of the rotating body. The components constituting the encoder main circuit 12 include, for example: an optical or magnetic sensor unit mounted on the rotating body; a signal conversion unit that converts the analog signal output from the sensor unit into a rectangular wave signal; and a memory for holding the position information, origin information, etc. of the motor, the rotating shaft, etc., which are omitted from the figure. The signal conversion unit, which is a component of the encoder main circuit 12, is composed of a comparator that compares the analog signal output from the sensor unit with a reference voltage and outputs a pulse when the analog signal is greater than the reference voltage. In addition, when the encoder 1 is configured as an optical encoder, the sensor unit, which is a component of the encoder main circuit 12, has a light emitting element and a light receiving element. When the encoder 1 is configured as a magnetic encoder, the sensor unit, which is a component of the encoder main circuit 12, has a sensor head.

[0035] The overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage based on the voltage supplied from the main power supply 10. In particular, according to the first embodiment, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage having a magnitude substantially equal to the encoder main circuit driving voltage based on the voltage supplied from the main power supply 10. The voltage supplied from the main power supply 10 has a magnitude different from the encoder main circuit driving voltage supplied from the internal power supply 11. Therefore, the overvoltage damage prevention circuit 13 has a structure that converts the input voltage into a voltage of different magnitude and outputs it, for example, it is composed of a voltage dividing resistor or a voltage regulator. For example, when the encoder main circuit driving voltage output by the internal power supply 11 is, for example, 3.3 [V], the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage of about 3.3 [V] based on the voltage (for example, 5 [V]) output by the main power supply 10. When the encoder main circuit driving voltage output by the internal power supply 11 is, for example, 1.5 [V], the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage of approximately 1.5 [V] based on the voltage (e.g., 5 [V]) output by the main power supply 10. When the encoder main circuit driving voltage output by the internal power supply 11 is, for example, 1 [V], the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage of approximately 1 [V] based on the voltage (e.g., 5 [V]) output by the main power supply 10.

[0036] Thus, according to the first embodiment, even if a short circuit occurs between the main power supply 10 that supplies power to the abnormality detection unit 14 and the internal power supply 11 that supplies power to the encoder main circuit 12, the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13 will be adjusted to a voltage having a magnitude substantially equal to the encoder main circuit driving voltage output from the internal power supply 11. The difference between these two potentials is small, and therefore, overvoltage will not be supplied to the encoder main circuit 12, thereby preventing damage to the electronic components constituting the encoder main circuit.

[0037] The abnormality detection unit 14 is driven by the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13, and monitors the encoder driving voltage output from the internal power supply 11 to detect abnormalities related to the internal power supply 11. For example, when the encoder driving voltage is greater than a predetermined upper limit threshold, the abnormality detection unit 14 determines that the internal power supply 11 has an abnormality, and outputs an internal power alarm signal to the blocking circuit 15. For example, when a short circuit occurs between the main power supply 10 and the internal power supply 11, the encoder driving voltage may be greater than a predetermined upper limit threshold. In this case, the abnormality detection unit 14 outputs an internal power alarm signal to the blocking circuit 15. In addition, as an option, the abnormality detection unit 14 may also determine that the internal power supply 11 has an abnormality when the encoder driving voltage is less than a predetermined lower limit threshold, and output an internal power alarm signal to the blocking circuit 15. The abnormality detection unit 14 may be composed of a combination of an analog circuit and an operation processing device, or may be composed of only an operation processing device, or may be composed of only an analog circuit. Among the operation processing devices that can constitute the abnormality detection unit 14, there are, for example, IC, LSI, CPU, MPU, DSP, etc. For example, when the abnormality detection unit 14 is constructed in the form of a software program, the function of the abnormality detection unit 14 can be realized by making the processing device operate according to the software program. Alternatively, a semiconductor integrated circuit or storage medium in which a software program realizing the function of the abnormality detection unit 14 is written can be constructed.

[0038] A blocking circuit 15 is provided between the internal power supply 11 and the encoder main circuit 12. The blocking circuit 15 receives the internal power supply alarm signal from the abnormality detection unit 14, thereby being able to grasp the situation that the abnormality detection unit 14 has detected an abnormality. When the abnormality detection unit 14 detects an abnormality, the blocking circuit 15 blocks the internal power supply 11 from supplying the encoder main circuit driving voltage to the encoder main circuit 12. When an abnormality such as an overvoltage is output by the internal power supply 11, the blocking circuit 15 blocks the internal power supply 11 from supplying the encoder main circuit driving voltage to the encoder main circuit 12, so that the overvoltage is not supplied to the encoder main circuit 12, and the damage of the electronic components constituting the encoder main circuit can be prevented. The blocking circuit 15 is composed of, for example, a semiconductor switching element or a relay. Examples of semiconductor switching elements include FET, IGBT, thyristor, GTO (Gate Turn-OFF thyristor), transistor, etc., and other semiconductor switching elements may also be used.

[0039] Next, refer to Figure 2 to Figure 4 An encoder according to a second embodiment of the present disclosure will be described.

[0040] Figure 2 It is a diagram showing an encoder according to a second embodiment of the present disclosure.

[0041] The encoder 1 of the second embodiment of the present disclosure drives the abnormality detection unit 14 with the voltage supplied from the main power supply 10 in normal state, and drives the abnormality detection unit 14 with the abnormality detection unit driving voltage having a magnitude substantially equal to the encoder main circuit driving voltage when a short circuit occurs between the main power supply 10 and the internal power supply 11. Therefore, the encoder 1 of the second embodiment of the present disclosure has the following features in addition to the reference Figure 1 The encoder 1 according to the first embodiment described above further includes a short-circuit detection unit 16 in addition to the configuration thereof.

[0042] The configuration and operation of the main power supply 10, the internal power supply 11, the encoder main circuit 12, and the blocking circuit 15 in the first embodiment are similar to those in the reference Figure 1 The first embodiment described is the same.

[0043] The short circuit detection unit 16 detects whether there is a short circuit between the main power supply 10 and the internal power supply 11. When a short circuit occurs between the main power supply 10 and the internal power supply 11, an overcurrent flows from the main power supply 10 to the overvoltage damage prevention circuit 13. Therefore, when the current from the main power supply 10 generates an overcurrent, a short circuit may occur between the main power supply 10 and the internal power supply 11, and therefore, the short circuit detection unit 16 outputs an overcurrent alarm signal to the overvoltage damage prevention circuit 13. The short circuit detection unit 16 may be composed of a combination of an analog circuit and an operation processing device, or may be composed of only an operation processing device, or may be composed of only an analog circuit. Among the operation processing devices that can constitute the short circuit detection unit 16, there are, for example, IC, LSI, CPU, MPU, DSP, etc. For example, when the short circuit detection unit 16 is constructed in the form of a software program, the function of the short circuit detection unit 16 can be realized by causing the operation processing device to operate according to the software program. Alternatively, a semiconductor integrated circuit or a storage medium in which a software program that realizes the function of the short circuit detection unit 16 is written can also be constructed.

[0044] The overvoltage damage prevention circuit 13 can grasp the situation that the short circuit detection unit 16 detects an abnormality by receiving an overcurrent alarm signal from the short circuit detection unit 16. When the overcurrent alarm signal is received from the short circuit detection unit 16, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage having a magnitude substantially equal to the encoder main circuit driving voltage according to the voltage supplied from the main power supply 10. In addition, when the short circuit detection unit 16 does not detect a short circuit, the overvoltage damage prevention circuit 13 outputs an abnormality detection unit driving voltage having a magnitude substantially equal to the voltage supplied from the main power supply 10. For example, if the voltage output by the main power supply 10 is 5 [V] and the voltage output by the internal power supply 11 is 3.3 [V], the abnormality detection unit driving voltage output by the overvoltage damage prevention circuit 13 when the short circuit detection unit 16 detects a short circuit is 3.3 [V], and when the short circuit detection unit 16 does not detect a short circuit, it is 5 [V].

[0045] The abnormality detection unit 14 is driven using the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13, and monitors the encoder driving voltage output from the internal power supply 11 to detect abnormalities related to the internal power supply 11. In the second embodiment, the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13 when the short circuit detection unit 16 detects a short circuit is a voltage having a magnitude substantially equal to the encoder main circuit driving voltage, and when the short circuit detection unit 16 does not detect a short circuit, it is a voltage having a magnitude substantially equal to the voltage supplied from the main power supply 10. The abnormality detection unit 14 is configured to be driven in either case with a voltage having a magnitude substantially equal to the encoder main circuit driving voltage or with a voltage having a magnitude substantially equal to the voltage supplied from the main power supply 10.

[0046] Thus, according to the second embodiment, even if the main power supply 10 that supplies power to the abnormality detection unit 14 and the internal power supply 11 that supplies power to the encoder main circuit 12 are short-circuited, the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13 when the main power supply 10 and the internal power supply 11 are short-circuited is adjusted to a voltage having a magnitude substantially equal to the encoder main circuit driving voltage output from the internal power supply 11, and the potential difference between the two is small, so that the encoder main circuit 12 is not supplied with an overvoltage, and the electronic components constituting the encoder main circuit can be prevented from being damaged. According to the second embodiment, the abnormality detection unit driving voltage having a magnitude substantially equal to the encoder main circuit driving voltage is output only when the main power supply 10 and the internal power supply 11 are short-circuited, and the abnormality detection unit driving voltage having a magnitude substantially equal to the voltage supplied from the main power supply 10 is output in other cases, so there is also an advantage that the power consumption of the main power supply 10 can be reduced.

[0047] Figure 3 1 is a diagram showing a specific example of a short circuit detection unit and an overvoltage damage prevention circuit in an encoder according to a second embodiment of the present disclosure. Figure 3 In the example shown, as an example, the voltage output by the main power supply 10 is set to 5 [V], and the voltage output by the internal power supply 11 is set to 3.3 [V].

[0048] When a short circuit occurs between main power supply 10 and internal power supply 11, an overcurrent flows from main power supply 10 to overvoltage damage prevention circuit 13. Short circuit detector 16 includes current detector 21 and determination unit 22 to detect the occurrence of an overcurrent in main power supply 10.

[0049] The current detection unit 21 detects the value of the current supplied from the main power supply 10. As a current detection method in the current detection unit 21, there is a method using a shunt resistor, for example. In this method, a shunt resistor is inserted between the main power supply 10 and the overvoltage damage prevention circuit 13, which are the current detection objects, and the potential difference between the two ends of the shunt resistor generated when the current flows through the shunt resistor is detected, and the current value is detected based on the voltage. The current value detected by the current detection unit 21 is transmitted to the determination unit 22.

[0050] The determination unit 22 determines whether the current supplied from the main power supply 10 generates an overcurrent based on whether the current value detected by the current detection unit 21 is above a predetermined threshold value. When the value of the current detected by the current detection unit 21 is above the threshold value, there may be a short circuit between the main power supply 10 and the internal power supply 11, so the determination unit 22 outputs an overcurrent alarm signal to the switch control unit 17 in the overvoltage damage prevention circuit 13. When the value of the current detected by the current detection unit 21 is less than the threshold value, the determination unit 22 determines that there is no short circuit between the main power supply 10 and the internal power supply 11. The determination unit 22 is composed of, for example, an AD converter and a comparator. The threshold value used for the determination process of overcurrent generation in the determination unit 22 needs to be obtained in advance before the actual use of the encoder 1. The threshold value is set to a value that is, for example, several tens of percent larger than the current value flowing during normal operation, but the value can also be changed arbitrarily.

[0051] The overvoltage damage prevention circuit 13 has a structure for converting an input voltage into a voltage of a different magnitude and outputting the voltage, and is composed of, for example, a voltage dividing resistor or a voltage regulator. Figure 3 In the example shown, the overvoltage damage prevention circuit 13 is configured using voltage dividing resistors.

[0052] like Figure 3 As shown, the overvoltage damage prevention circuit 13 includes a resistor R0, a resistor R1, a switch Tr1, and a switch control unit 17. A group consisting of the resistor R0, the resistor R1, and the switch Tr1 connected in series is connected to the main power supply 10. The connection point between the resistor R0 and the resistor R1 is connected to the abnormality detection unit 14. The resistance values ​​of the resistor R0 and the resistor R1 are set so that the potential VCC at the connection point between the resistor R0 and the resistor R1 generated by the current flowing from the main power supply 10 to the resistor R0 and the resistor R1 when the switch Tr1 is turned on is substantially equal to the voltage of the internal power supply 11 (for example, about 3.3 [V]). Examples of the switch Tr1 include FET, IGBT, thyristor, GTO (Gate Turn-OFF thyristor), transistor, etc., and other semiconductor switching elements may also be used.

[0053] The switch Tr1 is turned on and off by the switch control unit 17. That is, the switch control unit 17 turns on the switch Tr1 when receiving an overcurrent alarm signal from the short-circuit detection unit 16 and an internal power supply alarm signal from the abnormality detection unit 14. In this case, current also flows through the resistor R1, so the potential VCC at the connection point between the resistor R0 and the resistor R1 has a voltage of 3.3 [V] obtained by dividing the voltage 5 [V] of the main power supply 10 by the resistor R0 and the resistor R1. Therefore, 3.3 [V] is supplied to the abnormality detection unit 14 as a driving voltage. The switch control unit 17 turns off the switch Tr1 when not receiving an overcurrent alarm signal from the short-circuit detection unit 16. In this case, current does not flow through the resistor R1, so the potential VCC at the connection point between the resistor R0 and the resistor R1 has a voltage of 5 [V] of a magnitude substantially equal to the voltage supplied from the main power supply 10. Therefore, 5 [V] is supplied to the abnormality detection unit 14 as a driving voltage.

[0054] Figure 4 Yes means Figure 3 The flowchart of the operation flow of the short circuit detection unit and the overvoltage damage prevention circuit in the encoder shown. Figure 4 In the above description, the illustration of the generation process of the rotation information of the rotating body in the encoder main circuit 12 is omitted. The processes of steps S101 to S104 are repeatedly executed in a predetermined cycle.

[0055] First, in step S101 , the switch control unit 17 in the overvoltage destruction prevention circuit 13 determines whether an overcurrent alarm signal is output from the short-circuit detection unit 16 .

[0056] When it is determined in step S101 that the overcurrent alarm signal is not output from the short-circuit detection unit 16, the switch control unit 17 turns off the switch Tr1. In this case, no current flows through the resistor R1, so the overvoltage damage prevention circuit 13 outputs an abnormality detection unit driving voltage having a magnitude (5 [V]) substantially equal to the voltage supplied from the main power supply 10 (step S104).

[0057] When it is determined in step S101 that the overcurrent alarm signal is output from the short-circuit detection unit 16 , the process proceeds to step S102 .

[0058] In step S102 , the switch control unit 17 in the overvoltage destruction prevention circuit 13 determines whether the internal power supply alarm signal is output from the abnormality detection unit 14 .

[0059] When it is determined in step S102 that the internal power alarm signal is not output from the abnormality detection unit 14, the switch control unit 17 turns off the switch Tr1. In this case, no current flows through the resistor R1, so the overvoltage damage prevention circuit 13 outputs the abnormality detection unit driving voltage having a magnitude (5 [V]) substantially equal to the voltage supplied from the main power supply 10 (step S104). Then, the process returns to step S101.

[0060] When it is determined in step S102 that the internal power alarm signal is output from the abnormality detection unit 14, the switch control unit 17 turns on the switch Tr1. In this case, current also flows through the resistor R1, so the potential VCC at the connection point between the resistor R0 and the resistor R1 appears as a voltage of 3.3 [V] obtained by dividing the voltage 5 [V] of the main power supply 10 by the resistor R0 and the resistor R1, that is, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage having a magnitude (3.3 [V]) substantially equal to the encoder main circuit driving voltage (step S103). Thereafter, the process returns to step S101. As long as the internal power alarm signal is output from the abnormality detection unit 14, the overvoltage damage prevention circuit 13 continues to output an abnormality detection unit driving voltage having a magnitude (3.3 [V]) substantially equal to the encoder main circuit driving voltage. For example, as an option, when the main power supply 10 is turned on again after being cut off, the output from the overvoltage damage prevention circuit 13 is reset, and a voltage for driving the abnormality detection unit having a magnitude (5 [V]) substantially equal to the voltage supplied from the main power supply 10 is output again.

[0061] Next, refer to Figure 5 to Figure 7 An encoder according to a third embodiment of the present disclosure will be described. The third embodiment is an encoder according to the second embodiment in which a plurality of internal power supplies are provided.

[0062] Figure 5 : is a diagram showing an encoder according to a third embodiment of the present disclosure. Figure 5 and the following Figure 6 as well as Figure 7 In the example shown in the figure, the example in which the encoder 1 has two internal power supplies is described as an example, but the following description can also be applied to the example in which the encoder 1 has three or more internal power supplies. In addition, the structure and operation of the main power supply 10, the encoder main circuit 12 and the short-circuit detection unit 16 in the third embodiment are the same as those in the reference 1. Figure 2 The same is true for the second embodiment described above.

[0063] like Figure 5As shown, the encoder 1 of the third embodiment includes a first internal power supply 11-1 and a second internal power supply 11-2. The first internal power supply 11-1 and the second internal power supply 11-2 generate and output encoder main circuit driving voltages having different magnitudes. The configuration examples of the first internal power supply 11-1 and the second internal power supply 11-2 are similar to those in the reference Figure 1 The same as the internal power supply 11 described above. Figure 5 In the example shown, as an example, the first internal power supply 11 - 1 outputs 3.3 [V], and the second internal power supply 11 - 2 outputs 1.5 [V].

[0064] The first abnormality detection unit 14-1 and the second abnormality detection unit 14-2 are provided corresponding to the first internal power supply 11-1 and the second internal power supply 11-2, respectively. The configuration examples of the first abnormality detection unit 14-1 and the second abnormality detection unit 14-2 are similar to those in the reference Figure 1 The first abnormality detection unit 14-1 is driven by the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13, and monitors the encoder driving voltage output from the first internal power supply 11-1 to detect abnormalities related to the first internal power supply 11-1. The second abnormality detection unit 14-2 is driven by the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13, and monitors the encoder driving voltage output from the second internal power supply 11-2 to detect abnormalities related to the second internal power supply 11-2.

[0065] A first blocking circuit 15-1 is provided between the first internal power supply 11-1 and the encoder main circuit 12, and a second blocking circuit 15-2 is provided between the second internal power supply 11-2 and the encoder main circuit 12. Figure 1 The first blocking circuit 15-1 is the same as the blocking circuit 15 described above. When the first abnormality detection unit 14-1 detects an abnormality, the first blocking circuit 15-1 blocks the first internal power supply 11-1 from supplying the encoder main circuit driving voltage to the encoder main circuit 12. When the second abnormality detection unit 14-2 detects an abnormality, the second blocking circuit 15-2 blocks the second internal power supply 11-2 from supplying the encoder main circuit driving voltage to the encoder main circuit 12.

[0066] When the short circuit detection unit 16 detects a short circuit, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage based on the voltage supplied from the main power supply 10, and the abnormality detection unit driving voltage has a magnitude substantially equal to the encoder main circuit driving voltage output by the internal power supply whose abnormality is detected by the abnormality detection unit. That is, when the short circuit detection unit 16 detects a short circuit and the first abnormality detection unit 14-1 detects an abnormality in the first internal power supply 11-1, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage having a magnitude substantially equal to the encoder main circuit driving voltage output by the first internal power supply (approximately 3.3 [V]) based on the voltage supplied from the main power supply 10. When the short circuit detection unit 16 detects a short circuit and the second abnormality detection unit 14-2 detects an abnormality in the second internal power supply 11-2, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage having a magnitude substantially equal to the encoder main circuit driving voltage output by the second internal power supply (approximately 1.5 [V]) based on the voltage supplied from the main power supply 10. The first abnormality detector 14 - 1 and the second abnormality detector 14 - 2 are configured to be drivable by the abnormality detector driving voltage output from the overvoltage destruction prevention circuit 13 , that is, by any voltage of 5 [V], 3.3 [V], and 1.5 [V].

[0067] Thus, according to the third embodiment, even if a short circuit occurs between the main power supply 10 and any one of the plurality of internal power supplies 11-1 and 11-2, the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit 13 is adjusted to a voltage having a magnitude substantially equal to the encoder main circuit driving voltage output from the internal power supply that has detected the abnormality, and the potential difference between the main power supply 10 and the internal power supply that has detected the abnormality is small, so that an overvoltage is not supplied to the encoder main circuit 12, and damage to the electronic components constituting the encoder main circuit can be prevented. According to the third embodiment, only when a short circuit occurs between the main power supply 10 and the internal power supply that has detected the abnormality, the abnormality detection unit driving voltage having a magnitude substantially equal to the encoder main circuit driving voltage is output, and in other cases, the abnormality detection unit driving voltage having a magnitude substantially equal to the voltage supplied from the main power supply 10 is output, so there is also an advantage that the power consumption of the main power supply 10 can be reduced.

[0068] Figure 6 1 is a diagram showing a specific example of a short circuit detection unit and an overvoltage damage prevention circuit in an encoder according to a third embodiment of the present disclosure. Figure 6 In the example shown, as an example, the voltage output by the main power supply 10 is set to 5 [V], the voltage output by the first internal power supply 11-1 is set to 3.3 [V], and the voltage output by the second internal power supply 11-2 is set to 1.5 [V]. Other voltage levels are also possible.

[0069] The short-circuit detection unit 16 includes a current detection unit 21 and a determination unit 22 to detect the occurrence of an overcurrent in the main power supply 10. Figure 2 and Figure 3 The short-circuit detection unit 16 described above is the same.

[0070] The overvoltage damage prevention circuit 13 has a structure for converting the input voltage into a voltage of different magnitude and outputting it, and is composed of, for example, a voltage dividing resistor or a voltage regulator. Figure 6 In the example shown, the overvoltage damage prevention circuit 13 is configured using voltage dividing resistors.

[0071] like Figure 6 As shown, the overvoltage damage prevention circuit 13 includes: a resistor R0, a resistor R1, a resistor R2, a switch Tr1, a switch Tr2, and a switch control unit 17. A group consisting of a resistor R1 and a switch Tr1 connected in series is connected in parallel with a group consisting of a resistor R2 and a switch Tr2 connected in series. In addition, the group consisting of the resistor R1, the switch Tr1, the resistor R2, and the switch Tr2 and the resistor R0 are connected in series with the main power supply 10. The connection point of the resistor R0, the resistor R1, and the resistor R2 is connected to the first abnormality detection unit 14-1 and the second abnormality detection unit 14-2, respectively. The resistance values ​​of the resistor R0 and the resistor R1 are set so that when the switch Tr1 is turned on and the switch Tr2 is turned off, the potential VCC at the connection point of the resistor R0 and the resistor R1 generated by the current flowing from the main power supply 10 to the resistor R0 and the resistor R1 is substantially equal to the voltage magnitude (for example, about 3.3 [V]) of the first internal power supply 11-1. The resistance values ​​of the resistor R0 and the resistor R2 are set so that when the switch Tr1 is turned off and the switch Tr2 is turned on, the potential VCC at the connection point of the resistor R0 and the resistor R2 generated by the current flowing from the main power supply 10 to the resistor R0 and the resistor R2 is substantially equal to the voltage level of the second internal power supply 11-2 (for example, about 1.5 [V]). Examples of the switch Tr1 and the switch Tr2 include FET, IGBT, thyristor, GTO (Gate Turn-OFF thyristor), transistor, etc., and other semiconductor switch elements may also be used.

[0072] The switch Tr1 and the switch Tr2 are turned on and off by the switch control unit 17. That is, when the switch control unit 17 receives the overcurrent alarm signal from the short-circuit detection unit 16 and the first internal power alarm signal from the first abnormality detection unit 14-1, the switch Tr1 is turned on and the switch Tr2 is turned off. At this time, a current also flows through the resistor R1, so the potential VCC at the connection point between the resistor R0 and the resistor R1 has a voltage of 3.3 [V] obtained by dividing the voltage 5 [V] of the main power supply 10 by the resistor R0 and the resistor R1. That is, 3.3 [V] is supplied as a driving voltage to the first abnormality detection unit 14-1 and the second abnormality detection unit 14-2. That is, when the switch control unit 17 receives the overcurrent alarm signal from the short-circuit detection unit 16 and the second internal power alarm signal from the second abnormality detection unit 14-2, the switch Tr1 is turned off and the switch Tr2 is turned on. At this time, current also flows through the resistor R2, so the potential VCC at the connection point between the resistors R0 and R2 is 1.5 [V], which is a voltage obtained by dividing the voltage 5 [V] of the main power supply 10 by the resistors R0 and R2. That is, 1.5 [V] is supplied as a driving voltage to the first abnormality detection unit 14-1 and the second abnormality detection unit 14-2.

[0073] Figure 7 Yes means Figure 6 The flowchart of the operation flow of the short circuit detection unit and the overvoltage damage prevention circuit in the encoder shown. Figure 7 In the above, illustration is omitted regarding the process of generating the rotation information of the rotating body in the encoder main circuit 12. The processes of steps S201 to S206 are repeatedly executed in a predetermined cycle.

[0074] First, in step S201 , the switch control unit 17 in the overvoltage destruction prevention circuit 13 determines whether an overcurrent alarm signal is output from the short-circuit detection unit 16 .

[0075] When it is determined in step S201 that the overcurrent alarm signal is not output from the short-circuit detection unit 16, the switch control unit 17 turns off the switch Tr1 and the switch Tr2. At this time, no current flows through the resistors R1 and R2, so the overvoltage damage prevention circuit 13 outputs an abnormality detection unit driving voltage having a magnitude (5 [V]) substantially equal to the voltage supplied from the main power supply 10 (step S206). Thereafter, the process returns to step S201.

[0076] When it is determined in step S201 that the overcurrent alarm signal is output from the short-circuit detection unit 16 , the process proceeds to step S202 .

[0077] In step S202 , the switch control unit 17 in the overvoltage destruction prevention circuit 13 determines whether the first internal power supply alarm signal is output from the first abnormality detection unit 14 - 1 .

[0078] When it is determined in step S202 that the first internal power alarm signal is output from the first abnormality detection unit 14-1, the switch control unit 17 turns on the switch Tr1 and turns off the switch Tr2. At this time, a current flows through the resistor R1, so the potential VCC at the connection point between the resistor R0 and the resistor R1 has a voltage of 3.3 [V] obtained by dividing the voltage 5 [V] of the main power supply 10 by the resistor R0 and the resistor R1, that is, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage having a magnitude (3.3 [V]) substantially equal to the first encoder main circuit driving voltage output by the first internal power supply 11-1 (step S204). Thereafter, the process returns to step S201. As long as the first internal power alarm signal is output from the first abnormality detection unit 14-1, the overvoltage damage prevention circuit 13 continues to output an abnormality detection unit driving voltage having a magnitude (3.3 [V]) substantially equal to the first encoder main circuit driving voltage. For example, as an option, when the main power supply 10 is turned on again after being cut off, the output from the overvoltage damage prevention circuit 13 is reset, and a voltage for driving the abnormality detection unit having a magnitude (5 [V]) substantially equal to the voltage supplied from the main power supply 10 is output again.

[0079] If it is determined in step S202 that the first internal power supply alarm signal is not output from the first abnormality detection unit 14 - 1 , the process proceeds to step S203 .

[0080] In step S203 , the switch control unit 17 in the overvoltage destruction prevention circuit 13 determines whether the second internal power supply alarm signal is output from the second abnormality detection unit 14 - 2 .

[0081] When it is determined in step S203 that the second internal power alarm signal is output from the second abnormality detection unit 14-2, the switch control unit 17 turns off the switch Tr1 and turns on the switch Tr2. At this time, a current flows through the resistor R2, so the potential VCC at the connection point between the resistor R0 and the resistor R2 has a voltage of 1.5 [V] obtained by dividing the voltage 5 [V] of the main power supply 10 by the resistor R0 and the resistor R2, that is, the overvoltage damage prevention circuit 13 generates and outputs an abnormality detection unit driving voltage having a magnitude (1.5 [V]) substantially equal to the second encoder main circuit driving voltage output by the second internal power supply 11-2 (step S205). Thereafter, the process returns to step S201. As long as the second internal power alarm signal is output from the second abnormality detection unit 14-2, the overvoltage damage prevention circuit 13 continues to output an abnormality detection unit driving voltage having a magnitude (1.5 [V]) substantially equal to the second encoder main circuit driving voltage. For example, as an option, when the main power supply 10 is turned on again after being cut off, the output from the overvoltage damage prevention circuit 13 is reset, and a voltage for driving the abnormality detection unit having a magnitude (5 [V]) substantially equal to the voltage supplied from the main power supply 10 is output again.

[0082] If it is determined in step S203 that the second internal power alarm signal is not output from the second abnormality detection unit 14-2, the switch control unit 17 turns off the switch Tr1 and the switch Tr2. At this time, no current flows through the resistor R1 and the resistor R2, so the overvoltage damage prevention circuit 13 outputs the abnormality detection unit driving voltage having a magnitude (5 [V]) substantially equal to the voltage supplied from the main power supply 10 (step S206). Then, the process returns to step S101.

[0083] Furthermore, the processing consisting of step S202 and step S204 and the processing consisting of step S203 and step S205 may be executed in reverse order.

[0084] Explanation of symbols

[0085] 1 Encoder

[0086] 10 Main power supply

[0087] 11 Internal Power Supply

[0088] 11-1 First internal power supply

[0089] 11-2 Second internal power supply

[0090] 12 Encoder main circuit

[0091] 13 Overvoltage damage prevention circuit

[0092] 14 Abnormality Detection Department

[0093] 14-1 First abnormality detection unit

[0094] 14-2 Second abnormality detection unit

[0095] 15 Blocking circuit

[0096] 15-1 First blocking circuit

[0097] 15-2 Second blocking circuit

[0098] 16 Short circuit detection unit

[0099] 17 Switch control unit

[0100] 21 Current detection unit

[0101] 22 judgment unit.

Claims

1. An encoder, characterized in that: have: at least one internal power supply that generates and outputs a voltage for driving the encoder main circuit; an encoder main circuit that is driven using the encoder main circuit driving voltage supplied from the internal power supply and generates rotation information of a rotating body; an overvoltage damage prevention circuit that generates and outputs a voltage for driving the abnormality detection unit based on a voltage supplied from a main power supply; an abnormality detection unit that is driven by the abnormality detection unit driving voltage output from the overvoltage damage prevention circuit and detects an abnormality related to the internal power supply; as well as A blocking circuit blocks the internal power supply from supplying the encoder main circuit driving voltage to the encoder main circuit when the abnormality detection unit detects an abnormality.

2. The encoder according to claim 1, characterized in that The overvoltage damage prevention circuit generates and outputs an abnormality detection unit driving voltage having a magnitude equal to the encoder main circuit driving voltage based on a voltage supplied from the main power supply.

3. The encoder according to claim 1, characterized in that The encoder further comprises: a short circuit detection unit, which detects whether there is a short circuit between the main power supply and the internal power supply. When the short circuit detection unit detects a short circuit, the overvoltage damage prevention circuit generates and outputs an abnormality detection unit driving voltage having a magnitude equal to the encoder main circuit driving voltage based on the voltage supplied from the main power supply. When the short-circuit detection unit does not detect a short circuit, the overvoltage destruction prevention circuit generates and outputs a voltage for driving the abnormality detection unit having a magnitude equal to a voltage supplied from the main power supply.

4. The encoder according to claim 3, characterized in that When the short-circuit detection unit detects a short circuit, the overvoltage damage prevention circuit generates and outputs an abnormality detection unit driving voltage having a magnitude equal to the encoder main circuit driving voltage based on the voltage supplied from the main power supply, wherein the encoder main circuit driving voltage is output by the internal power supply whose abnormality is detected by the abnormality detection unit.

5. The encoder according to claim 3 or 4, characterized in that The short circuit detection unit has: a current detection unit that detects a current value supplied from the main power supply; and The determination unit determines that there is a short circuit between the main power supply and the internal power supply when the current value detected by the current detection unit is greater than a predetermined threshold value, and determines that there is no short circuit between the main power supply and the internal power supply when the current value detected by the current detection unit is less than the threshold value.

6. The encoder according to claim 1, characterized in that The plurality of internal power supplies respectively generate and output encoder main circuit driving voltages having different magnitudes. A plurality of the abnormality detection units are provided corresponding to the plurality of internal power supplies, respectively.

7. The encoder according to claim 1, characterized in that The internal power supply generates and outputs a voltage for driving the encoder main circuit based on a voltage supplied from the main power supply.

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