JP2008203175A - Rotary encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary encoder capable of estimating the remaining lifetime, based on the degree of reduction in the luminous energy in a light-emitting element, by a data request from the outside. <P>SOLUTION: This rotary encoder is provided with a DC component computing part 12 for calculating the DC component of the quantity of light received measured by a photoreception element of an original signal part 11, an A/D conversion part 13 for A/D-converting the value calculated by the DC component computing part 12, a storage part 14 for storing an initial quantity of light received computed by the DC component computing part 12 and the A/D conversion part 13; a status detecting part 15 for comparing the each time measured photoreception quantity with the initial photoreception quantity computed by the DC component computing part 12 and the A/D conversion part 13, to calculate a luminous energy reduction rate; and a data communication part 16 for converting data of the original signal part 11 and the status detecting part 15 into serial data, when a serial signal of a data transmission request signal from the outside is received, followed to be output, and a specified data request signal is input into the data communication part 16 to detect the luminous energy reduction rate, irrespective of the rotation of a motor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical rotary encoder, and in particular, provides a rotary encoder that can estimate the remaining life of a light emitting element immediately after power-on.

  In recent years, the demand for AC servomotors has increased due to the ease of motor maintenance, and serial communication type rotary encoders with fewer signal lines have been increasing as position detectors incorporated in AC servomotors.

  Under such circumstances, even if the light emission amount of the light emitting element fluctuates due to external factors such as temperature, the light reception amount of the light receiving element is fed back and automatically corrected to a predetermined light reception amount by the calculation unit, so that the reliability is high There have been proposals for obtaining a rotary encoder.

  This rotary encoder is effective for correction when the light emission amount fluctuates, but the light reception amount also varies depending on the angular position, so it is necessary to rotate the shaft to grasp the maximum and minimum values of the light reception amount. There is. This indicates that the amount of received light cannot be detected only by turning on the power of the rotary encoder. Even if there is an abnormality in the light emitting element, the abnormality could not be detected unless it is rotated once.

Therefore, the forward voltage of the light emitting element is monitored to determine whether it is within a predetermined voltage range, the operating state of the light emitting element is detected, and the operating state is transmitted as serial data with an external data transmission request signal. Can detect the presence / absence of abnormal operation of light emitting element (abnormal forward voltage drop due to overcurrent of light emitting element, small forward voltage drop due to insufficient light emitting element operating current, wiring open failure of light emitting element operating part, etc.) A high optical encoder has been proposed (see, for example, Patent Document 1).
JP 2004-309203 A

  On the other hand, if the drive motor suddenly stops due to its life or the like, the damage to the production line will increase, so it is necessary to know in advance the degree of performance deterioration of the main parts.

  If the technique of the above-mentioned patent document is used, the presence or absence of abnormality of the light emitting element can be detected without rotating the rotary encoder. However, this is a comparison with a constant value, and it is difficult to predict the lifetime because the degree of decrease in the amount of light due to deterioration over time of the light emitting element corresponding to the remaining lifetime as a rotary encoder cannot be detected.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a rotary encoder capable of estimating the remaining life from the degree of decrease in the light amount of a light-emitting element in response to an external data request.

In order to solve the above problems, the present invention provides an original signal unit that outputs rotational position data in accordance with the rotation of a motor, and a DC component calculation unit that calculates a DC component of the amount of received light measured by a light receiving element of the original signal unit. An A / D converter that performs analog-to-digital conversion on the value calculated by the DC component calculator, a storage that stores the initial received light amount calculated by the DC component calculator and the A / D converter, A status detection unit that calculates the light amount reduction rate of the light emitting element by comparing the initial received light amount calculated by the DC component calculation unit and the A / D conversion unit with the received light amount measured each time, and a data transmission request signal from the outside When receiving a certain serial signal, it has a data communication unit that converts the data of the original signal unit and the status detection unit into serial data and outputs it, and inputs a specific data request signal to the data communication unit regardless of the rotation of the motor. A rotary encoder and detects a light amount decrease ratio.

  In addition, an original signal unit that outputs rotational position data according to the rotation of the motor, and a light emitting element that controls the supply current of the light emitting element by feeding back the received light amount in order to keep the received light amount of the light receiving element of the original signal unit constant A supply current control unit, an A / D conversion unit for analog-to-digital conversion of the amount of current supplied to the light emitting element of the original signal unit, and a memory for storing an initial current to the light emitting element converted by the A / D conversion unit A status detector that compares the amount of current supplied to the initial light emitting element stored in the storage unit and the amount of current supplied to the light emitting element measured each time to calculate the light quantity reduction rate of the light emitting element; When receiving a serial signal that is a data transmission request signal, a data communication unit that converts the data of the original signal unit and the status detection unit into serial data and outputs the data, and outputs a specific data request signal regardless of the rotation of the motor. Enter the data communication unit is a rotary encoder and detects a light amount decrease ratio.

  According to the rotary encoder of the present invention, since the rate of decrease in the amount of light received by the light emitting element can be grasped only by requesting specific data different from normal, regardless of the rotation of the motor, the remaining life can be estimated. .

  Similarly, the remaining life can be estimated by grasping the decrease in the amount of received light by current comparison.

  Thereby, it is possible to accurately grasp the replacement time of the servo motor or the rotary encoder from the remaining life of the rotary encoder, and it is possible to prevent damage due to a sudden failure.

  Calculated by an original signal unit that outputs rotational position data according to the rotation of the motor, a DC component calculation unit that calculates a DC component of the amount of received light measured by the light receiving element of the original signal unit, and a DC component calculation unit An A / D converter that converts the value from analog to digital, a storage that stores the initial received light amount calculated by the DC component calculator and the A / D converter, a DC component calculator and the A / D converter The status detection unit that calculates the light quantity reduction rate of the light emitting element by comparing the initial received light amount calculated in each case and the received light amount measured each time, and the original signal unit upon receiving a serial signal that is a data transmission request signal from the outside A data communication unit that converts the status detection unit data into serial data and outputs it. After turning on the power to the rotary encoder, a specific data request signal is input to the data communication unit regardless of the motor rotation. Detecting a light amount decrease ratio Te.

  Hereinafter, a rotary encoder according to Embodiment 1 of the present invention will be described with reference to the drawings.

  In FIG. 1, the original signal unit 11 outputs rotational position data in accordance with the rotation of the motor. The DC component calculation unit 12 calculates the DC component of the received light amount measured by the light receiving element of the original signal unit 11. The A / D converter 13 performs analog-digital conversion on the value calculated by the DC component calculator 12.

The storage unit 14 stores the initial received light amount calculated by the DC component calculation unit and the A / D conversion unit. The status detection unit 15 compares the initial light reception amount stored in the storage unit 14 with the light reception amount measured each time, and detects the light amount reduction rate of the light emitting element. The data communication unit 16 receives a serial signal that is a data transmission request signal from the outside, converts the data of the original signal unit 11 and the status detection unit 15 into serial data, and outputs the serial data.

FIG. 2 illustrates the operation of the original signal unit 11 and is data of 0 to 2 ^m −1 in monotone increase at CCW rotation and monotone decrease at CW rotation at an absolute position within 360 ° of rotation at mbit resolution. One rotation data and the number of rotations of the motor are output, and multi-rotation data which is an increase change during CCW rotation and a decrease change during CW rotation is output.

  FIG. 3 is a configuration example of a part of the original signal unit and the DC component calculation unit. The original signal section is composed of current-voltage conversion resistors 31a and 31b, light receiving elements 32a and 32b, a load resistor 33 and a light emitting element 34 connected to an operating voltage source. The signals detected by the light receiving element 32a and the light receiving element 32b have a phase difference of 180 degrees. The DC component calculation unit 12 includes an amplifier 35 and resistors 36a, 36b, and 36c.

  FIG. 4 shows the relationship between the light emission amount of the light emitting element 34 and the light reception amount of the light receiving element 32, and has a characteristic that the light reception amount of the PD increases in proportion to the increase of the light emission amount of the LED.

  FIG. 8 shows a configuration example of the data communication unit, and the bidirectional bus 81 is composed of a line driver receiver that performs switching between transmission and reception of serial data with the outside. The receiver 82 receives a serial signal which is a data transmission request signal from the outside, and outputs a transmission start signal after normal reception is completed. The transmitter 83 converts data from the original signal unit and the status detection unit and communication error detection data generated from these data into serial data in response to the transmission start signal.

  FIG. 9 shows a configuration example of serial data (signal). The RX signal, which is a request signal from the outside corresponding to the servo amplifier to the encoder, is composed of a command part indicating a data transmission request, while transmission from the encoder to the outside. The TX signal, which is a signal, includes a command part, a transmission data part, a command part, and a transmission error detection data part generated from the transmission data part received by the encoder.

  The detailed operation will be described below. First, light output from the light emitting element 34 when the initial power is turned on is received by the light receiving element 32a and the light receiving element 32b, and is added to an adding circuit including the amplifier 35, the resistor 36a, the resistor 36b, and the resistor 36c of the DC component calculation unit 12. Then, the DC component is calculated, digitally converted by the A / D converter 13 and stored in the storage unit 14.

  In FIG. 4, when the light emitting element 34 deteriorates with time and the amount of emitted light decreases, the amount of light received by the light receiving element decreases in proportion, so the initial amount of received light stored in the storage unit 14 is measured each time. And the status detection unit can calculate the light amount reduction rate of the light emitting element 34.

  As described above, the light amount reduction rate of the light emitting element can be detected regardless of whether the rotary encoder is rotated. For this reason, when the light quantity of the light emitting element used for the rotary encoder decreases due to deterioration over time, when an abnormality occurs in the circuit of the external signal source 11 or when there is a specific data request from the outside regardless of position or rotation. By simply doing this, the degree of decrease in the amount of light emission can be transmitted to the outside (such as a host system) as serial data, and the remaining lifetime of the light emitting element can be estimated.

  Therefore, it is possible to accurately grasp the replacement time of the servo motor or the rotary encoder from the remaining life of the rotary encoder, and it is possible to prevent damage to the equipment due to the failure of the rotary encoder.

  The same functions as those in the first embodiment will be described below using the same reference numerals for the rotary encoder in the second embodiment of the present invention.

  In FIG. 5, the original signal unit 11 outputs rotational position data in accordance with the rotation of the motor. The light emitting element supply current control unit 51 controls the supply current of the light emitting element by feeding back the light receiving amount in order to keep the light receiving amount of the light receiving element of the original signal portion constant. The A / D conversion unit 13 performs analog-digital conversion on the amount of current supplied to the light emitting element of the original signal unit.

  The storage unit 14 stores the initial supply current amount to the light emitting element calculated by the A / D conversion unit. The status detection unit 15 compares the initial received light amount stored in the storage unit 14 with the amount of current supplied to the light emitting element measured each time, and detects the light amount reduction rate of the light emitting element. The data communication unit 16 receives a serial signal that is a data transmission request signal from the outside, converts the data of the original signal unit 11 and the status detection unit 15 into serial data, and outputs the serial data.

  FIG. 6 is a configuration example of a part of the original signal unit and the light emitting element supply current control unit. The original signal unit 11 includes current-voltage conversion resistors 31a and 31b, light receiving elements 32a and 32b, a load resistor 33 and a light emitting element 34 connected to an operating voltage source, and a light emitting element supply current control unit 51 includes an amplifier 61a. , 61b, transistor 62, and resistors 63a, 63b, 63c.

  FIG. 7 shows the relationship between the light emission amount of the light emitting element 34 and the light emitting element supply current. The light emission element supply current increases in inverse proportion to the decrease in the light emission amount of the LED.

  The detailed operation will be described below. First, the amount of current supplied to the light emitting element 34 when the initial power is turned on is converted by the voltage drop of the resistor 33. The value is digitally converted by the A / D conversion unit 13 and stored in the storage unit 14.

  The current supplied to the light emitting element 34 is calculated by the light emitting element supply current control unit 51 based on the amount of light received by the light receiving elements 32a and 32b, by the amplifier 61a, and compared with the reference voltage by the amplifier 61b. The voltage applied to the transistor 62 is determined, and the supply current to the light emitting element 34 is controlled so that the amount of received light is constant.

  In FIG. 4, when the light emitting element 34 deteriorates with time and the amount of emitted light decreases, the amount of current supplied to the light emitting element increases in inverse proportion. Therefore, the initial amount of supplied current stored in the storage unit 14 is measured each time. The light quantity reduction rate of the amount of received light can be calculated by performing comparison calculation processing with the supplied current amount and the status detection unit.

  As described above, the light amount reduction rate of the light emitting element can be detected regardless of whether the rotary encoder is rotated. For this reason, when the light quantity of the light emitting element used for the rotary encoder decreases due to deterioration over time, when an abnormality occurs in the circuit of the external signal source 11 or when there is a specific data request from the outside regardless of position or rotation. The degree of decrease in the amount of light emission can be transmitted to the outside (such as a host system) with serial data simply by estimating the remaining life of the light emitting element.

  Therefore, it is possible to accurately grasp the replacement time of the servo motor or the rotary encoder from the remaining life of the rotary encoder, and it is possible to prevent damage to the equipment due to the failure of the rotary encoder.

  The rotary encoder of the present invention is useful for maintenance inspection and the like because the remaining life can be estimated from the degree of light quantity reduction of the light emitting element without rotating the motor.

1 is a block diagram of a rotary encoder according to a first embodiment of the present invention. Explanatory drawing of original signal part data in the present invention 1 is a block diagram around a DC component calculation unit in Embodiment 1 of the present invention. Operational explanatory diagram of the light receiving element in Example 1 of the present invention Block diagram of a rotary encoder in Embodiment 2 of the present invention Block diagram around a light emitting element supply current control unit in Example 2 of the present invention Explanatory drawing of operation | movement of the issuing element in Example 2 of this invention Block diagram of data communication unit in the present invention The figure explaining the structure of the serial data in this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Original signal part 12 DC component calculating part 13 A / D conversion part 14 Storage part 15 Status detection part 16 Data communication part 31a, 31b Current-voltage conversion resistor 32a, 32b Light receiving element 33 Load resistor 34 Light emitting element 35 Amplifier 36a, 36b, 36c Resistor 51 Light emitting element supply current control unit 61a, 61b Amplifier 62 Transistor 63a, 63b, 63c Resistor 64 Capacitor 81 Bidirectional bus 82 Receiver 83 Transmitter

Claims (2)

Calculated by an original signal unit that outputs rotational position data according to the rotation of the motor, a DC component calculation unit that calculates a DC component of the amount of received light measured by the light receiving element of the original signal unit, and a DC component calculation unit An A / D converter that converts the value from analog to digital, a storage that stores the initial received light amount calculated by the DC component calculator and the A / D converter, a DC component calculator and the A / D converter The status detection unit that calculates the light quantity reduction rate of the light emitting element by comparing the initial received light amount calculated in each case and the received light amount measured each time, and the original signal unit upon receiving a serial signal that is a data transmission request signal from the outside A data communication unit that converts the data of the status detection unit into serial data and outputs the data, and regardless of the rotation of the motor, a specific data request signal is input to the data communication unit to detect the light quantity reduction rate Rotary encoder that. An original signal section that outputs rotational position data according to the rotation of the motor, and a light emitting element supply current that controls the supply current of the light emitting element by feeding back the received light amount in order to keep the light receiving amount of the light receiving element of the original signal section constant A control unit, an A / D conversion unit that performs analog-to-digital conversion of the amount of current supplied to the light emitting element of the original signal unit, and a storage unit that stores an initial current to the light emitting element converted by the A / D conversion unit; A status detection unit that compares the amount of current supplied to the initial light emitting element stored in the storage unit and the amount of current supplied to the light emitting element measured each time to calculate the light quantity reduction rate of the light emitting element, and data transmission from the outside When receiving a serial signal, which is a request signal, a data communication unit that converts the data of the original signal unit and the status detection unit into serial data and outputs the data, and passes a specific data request signal through the data regardless of the motor rotation. A rotary encoder, characterized in that by entering a part for detecting a light amount decrease ratio.