JP2004309203A - Rotary encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary encoder for discriminating the presence or absence of the operation failure of a light-emitting element immediately after power is charged even without rotation. <P>SOLUTION: The rotary encoder comprises a load resistor 31 connected to an operating voltage source, and the light-emitting element 32, and the operating current of the light-emitting element 32 is determined by the value of the load resistor 31. A first voltage detector 33 is set to an operating lower-limit value. When the forward voltage of the light-emitting element 32 is equal to or more than a first specific voltage, and less than the first specific voltage, "H" and "L" are outputted, respectively. Conversely, a second voltage detector 34 is set to an operation upper-limit value. When the forward voltage of the light-emitting element 32 is equal to or more than a second specific voltage, and less than the second specific value, "H" and "L" are outputted, respectively. A logic circuit 35 outputs "L" (normal) and "H"(abnormal) as a light-emitting element operation flag when the forward voltage in the light-emitting element 32 is equal to or more than an operation lower-limit value and less than an operation upper-limit value, and the others, respectively, according to the output of the first and second voltage detectors 33, 34. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotary encoder that transmits rotational position information of a rotator by bidirectional serial communication means.
[0002]
[Prior art]
In recent years, demand for AC servomotors has increased due to ease of motor maintenance, and serial communication type rotary encoders having fewer signal lines as position detectors incorporated in AC servomotors have been increasing.
[0003]
Under such circumstances, even if the light emission amount of the light emitting element fluctuates due to an external factor such as temperature, the light reception amount of the light receiving element is fed back and automatically corrected to a predetermined light reception amount to obtain a highly reliable rotary encoder. Some are known (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP 2000-193492 A [0005]
[Problems to be solved by the invention]
However, the above-described conventional configuration is effective for correction when the light emission amount fluctuates. However, since the light reception amount also fluctuates depending on the angular position, the axis for grasping the maximum value and the minimum value of the light reception amount is important. Need to rotate.
[0006]
This means that it is impossible to detect the amount of received light only by turning on the power of the rotary encoder. Even if the light emitting element has an abnormality, the abnormality cannot be detected unless the light emitting element is once rotated.
[0007]
An object of the present invention is to solve the above-mentioned conventional problem, and an object of the present invention is to provide a rotary encoder that can determine whether or not there is an operation abnormality of a light emitting element immediately after power-on without rotating.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, a rotary encoder according to the present invention measures a forward voltage of a light emitting element of an original signal section that outputs rotational position data according to rotation of a motor, and a light emitting element of the original signal section within a predetermined voltage range. And a status detection unit for detecting the operating state of the light emitting element by determining whether the serial signal is a data transmission request signal from the outside, and converts the data of the original signal unit and the status detection unit into serial data. And a data communication unit for outputting.
[0009]
With this configuration, even when the rotary shaft is in a stationary state immediately after turning on the power of the encoder, abnormal operation of the light emitting element (a large forward voltage drop due to a light emitting element operating overcurrent, a small forward voltage drop due to a shortage of the light emitting element operating current, light emission) An abnormality such as a wiring open failure of the element operation section) can be easily detected.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
In order to solve the above problem, a rotary encoder according to claim 1 measures an original signal unit that outputs rotational position data in accordance with rotation of a motor, and measures a forward voltage of a light emitting element of the original signal unit to obtain a predetermined signal. A status detection unit that determines whether the voltage is within a voltage range and detects an operation state of the light emitting element, and when receiving a serial signal that is a data transmission request signal from the outside, converts the data of the original signal unit and the status detection unit into serial data. And a data communication unit that converts the data into an output.
[0011]
Also, in the rotary encoder according to claim 2 or 3, in the status detection unit, the forward voltage of the light emitting element is detected by the analog-to-digital converter, and the digitally converted value is within a predetermined range. Is determined by logical processing. Alternatively, the forward voltage of the light emitting element is compared by the first voltage comparator set to the operation lower limit and the second voltage comparator set to the operation upper limit, and the first voltage comparator and the second voltage comparator are set to the second voltage comparator. The operation state of the light emitting element is detected according to the output logic value (H or L) of the voltage comparator.
[0012]
In this way, when the power of the encoder is turned on, the forward voltage of the light emitting element is measured and compared with a predetermined value, so that the presence or absence of an abnormal operation of the light emitting element can be detected.
[0013]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
In FIG. 1, an original signal unit 11 outputs rotation position data according to rotation of a motor. The status detection unit 12 measures the forward voltage of the light emitting element of the original signal unit 11 and detects whether there is a voltage abnormality. The data communication unit 13 receives a serial signal as a data transmission request signal from the outside, converts the data of the original signal unit 11 and the status detection unit 12 into serial data, and outputs the serial data.
[0015]
FIG. 2 illustrates the operation of the original signal unit 11 and is data of 0 to 2 ^m -1 in which the absolute position within 360 ° per rotation is monotonically increased at CCW rotation and monotonically decreased at CW rotation at mbit resolution. One rotation data and the number of rotations of the motor, multi-rotation data which is an increase change during CCW rotation and a decrease change during CW rotation are output.
[0016]
FIG. 3 is a configuration example of a light emitting element drive circuit unit that is a part of the original signal unit 11 and a status detection unit 12.
[0017]
The light emitting element drive circuit section includes a load resistor 31 and a light emitting element (LED) 32 connected to an operating voltage source, and determines the operating current of the light emitting element 32 according to the value of the load resistor 31. The status detection unit 12 includes a first voltage detector 33, a second voltage detector 34, and a logic circuit 35.
[0018]
The first voltage detector 33 is set to the operation lower limit, and outputs “H” when the forward voltage of the light emitting element 32 is equal to or higher than the first predetermined voltage, and outputs “L” when the forward voltage is lower than the first predetermined voltage. On the other hand, the second voltage detector 34 is set to the operation upper limit value, and outputs “H” when the forward voltage of the light emitting element 32 is equal to or higher than the second predetermined voltage, and outputs “L” when the forward voltage is lower than the second predetermined voltage. .
[0019]
The logic circuit 35 determines a light emitting element operation flag if the forward voltage of the light emitting element 32 is equal to or more than the lower limit of operation and less than the upper limit of operation in accordance with the outputs of the first voltage detector 33 and the second voltage detector 34. Is output as "L" (normal), and otherwise "H" (abnormal).
[0020]
Here, the first voltage detector 33 and the second voltage detector 34 include a commercially available voltage detection IC that outputs “H” or “L” for a predetermined voltage value, a reference voltage source, and a comparator IC. , A window comparator, an analog-digital converter, or the like, which combines the above.
[0021]
FIG. 4 shows the relationship between the operating current of the light emitting element (LED) and the forward voltage. The characteristic is that the forward voltage increases as the operating current of the LED increases.
[0022]
FIG. 5 shows an example of the configuration of the data communication unit. The bidirectional bus 51 includes a line driver receiver for switching between transmission and reception of serial data with the outside. The receiver 52 receives a serial signal as a data transmission request signal from the outside, and outputs a transmission start signal after normal reception is completed. The transmitter 53 converts the data from the original signal section and the status detection section and the communication error detection data generated from these data into serial data by the transmission start signal.
[0023]
FIG. 6 shows a configuration example of serial data (signal). An RX signal corresponding to a servo amplifier, which is a request signal from the outside to the encoder, includes a command portion indicating a data transmission request. The TX signal, which is a signal, includes the command part, the transmission data part, the command part, and the transmission error detection data part generated from the transmission data part received by the encoder.
[0024]
Hereinafter, detailed operations will be described with reference to the drawings.
[0025]
In FIG. 4, when the normal operating current range of the light emitting element (LED) is not less than I1 and less than I2, the forward voltage of the light emitting element is not less than V1 and less than V2.
[0026]
Here, when the light emitting element drive circuit in FIG. 3 fails in the open state, no current flows to the light emitting element 32, and the forward voltage of the light emitting element becomes less than V1 or more than V2 depending on the open position.
[0027]
The same applies when the value of the load resistor 31 of the light emitting element drive circuit changes, for example, when the resistance value changes greatly (current of the light emitting element 32 = small) or changes small (current of the light emitting element 32 = large). Thus, the forward voltage of the light emitting element 32 is lower than V1 or higher than V2.
[0028]
Furthermore, even if the forward voltage of the light emitting element changes due to deterioration over time, an abnormality in the operation of the light emitting element can be similarly detected.
[0029]
Needless to say, the presence / absence of the abnormality can be detected regardless of the presence / absence of rotation of the rotary encoder.
[0030]
As described above, if an error occurs in the light emitting element or light emitting element drive circuit used for the rotary encoder, the abnormality of the light emitting element operation is detected regardless of the position or rotation, and this abnormality is sent to the host system by serial data. Can be transmitted.
[0031]
【The invention's effect】
As is apparent from the above embodiments, according to the inventions of claims 1 to 3, the forward voltage of the light emitting element is measured, and the time when the encoder power supply is turned on without involving the rotation operation of the encoder is measured. Therefore, an emergency stop of the system can be realized early, and a highly reliable motor drive system can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of a main part of a rotary encoder of the present invention. FIG. 2 is an explanatory diagram of original signal part data of the present invention. FIG. 3 is a block diagram of a part of an original signal part and a status detector in an embodiment of the present invention. FIG. 4 is an explanatory diagram of the operation of the light emitting element in the present invention. FIG. 5 is a block diagram of a data communication unit in the embodiment of the present invention. FIG. 6 is a diagram for explaining the configuration of serial data in the embodiment of the present invention. Description]
Reference Signs List 11 original signal section 12 status detection section 13 data communication section 31 load resistor 32 light emitting element 33 first voltage detector 34 second voltage detector 35 logic circuit 51 bidirectional bus 52 receiver 53 transmitter

Claims (3)

The operation state of the light emitting element is detected by measuring the forward voltage of the light emitting element of the original signal part that outputs the rotational position data according to the rotation of the motor and determining whether the voltage is within a predetermined voltage range. A rotary encoder comprising: a status detection unit; and a data communication unit that, when receiving a serial signal as an external data transmission request signal, converts the data of the original signal unit and the status detection unit into serial data and outputs the serial data. 2. The rotary encoder according to claim 1, wherein the status detector detects a forward voltage of the light emitting element by an analog-to-digital converter, and determines by logic processing whether the digitally converted value is within a predetermined range. In the status detection unit, the forward voltage of the light emitting element is compared by a first voltage comparator set to an operation lower limit value and a second voltage comparator set to an operation upper limit value. 2. The rotary encoder according to claim 1, wherein an operation state of the light emitting element is detected according to an output logic value (H or L) of the second voltage comparator.

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