JP2002318138A - Amplitude correcting method for encoder signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an amplitude of a sinusoidal wave constant and to improve accuracy by controlling closed loop feedback to a comparator side for an amplitude detection value of the output sinusoidal signal. SOLUTION: An amplitude correcting method according to the present invention obtains an encoder signal with high accuracy which eliminates adjustment with a conventional variable resistor through feedback input of an amplitude detection value (20A) obtained by calculating amplitudes of output signals (2A and 3A) to a comparator (12) prior to a light emitting element (1) or an amplifier (4) driving magnetic sensors (51 and 52) so as to make an amplitude of a sinusoidal signal (10) constant with a closed loop control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the amplitude of an encoder signal, and more particularly to a method for automatically adjusting a current applied to a light emitting element or a voltage applied to a magnetic sensor by a closed loop feedback circuit in accordance with amplitude fluctuation of an output signal. The present invention also relates to a novel improvement for eliminating the need for a variable resistor for amplitude adjustment which has been conventionally used.

[0002]

2. Description of the Related Art As a conventional method of correcting the amplitude of an encoder signal of this type, a typical configuration is as follows.
The configuration shown in FIG. 4 can be given. That is,
In FIG. 4, a reference numeral 1 denotes a light-emitting element formed of an LED, and a first variable resistor VR1 for adjusting the applied current is connected to the light-emitting element 1 in series. The light from the light emitting element 1 is configured to be received by first and second light receiving elements 2 and 3 arranged at a predetermined interval from each other. Second and third variable resistors VR for adjusting the signal level
2, VR3 are connected.

[0003] First and second output signals 2A, 3A having different phases from each other composed of sine wave signals of the light receiving elements 2, 3 respectively.
Is input to input terminals 5 and 6 of an amplifier 4 including an operational amplifier having a fourth variable resistor VR4, and is amplified by the amplifier 4 to output a sine wave signal 10 having a predetermined amplitude value.

[0004]

The conventional method for correcting the amplitude of an encoder signal is constituted as described above.
The following issues existed. That is, a light emitting element,
A variable resistor is provided for each light receiving element and amplifier, and adjustment of the applied current to the light emitting element, adjustment of the output of the light receiving element, and output adjustment of the amplifier must be performed manually, and adjustment is performed at the time of assembly. However, the adjustment value sometimes fluctuates after being incorporated into the device, and it has been difficult to maintain a highly accurate amplitude value. Further, in order to increase the accuracy, each electronic component such as a variable resistor having a small variation value must be used, and it has been difficult to absorb the cost for consumer use.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. In particular, the present invention provides a closed-loop feedback circuit for applying a current applied to a light emitting element or a voltage applied to a magnetic sensor in accordance with an amplitude fluctuation of an output signal. It is an object of the present invention to provide a method for correcting the amplitude of an encoder signal, which automatically adjusts the amplitude of the signal and eliminates the need for a conventionally used variable resistor for amplitude adjustment.

[0006]

According to a method of correcting the amplitude of an encoder signal according to the present invention, light from a light-emitting element is received by a light-receiving element via a rotary code plate, and an output signal obtained from the light-receiving element is passed through an amplifier. And amplifying the sine wave signal to obtain the sine wave signal, and correcting the amplitude of the sine wave signal. Is a method of providing a feedback input to a comparator provided with a target amplitude command value provided in a stage preceding the light emitting element current control unit that drives
Further, the magnetic gear is rotated while an applied voltage is supplied to the magnetic sensor via an amplifier, and a sine wave signal corresponding to the shape of the magnetic gear is obtained from the magnetic sensor, and the amplitude of the sine wave signal is reduced. In the amplitude correction method for an encoder signal to be corrected, an amplitude detection value obtained by calculating the amplitude of the sine wave signal is provided at a stage preceding the amplifier that generates the applied voltage, and a target amplitude command value is input. This is a method of performing feedback input to the comparator.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of an encoder signal amplitude correction method according to the present invention will be described below with reference to the drawings. The same or equivalent parts as those in the conventional example will be described using the same reference numerals. In FIG. 1, reference numeral 1 denotes a light-emitting element composed of an LED. The light-emitting element 1 includes a light-emitting element current control unit 1 composed of a driving element such as a transistor for driving the light-emitting element 1.
1, a comparator 12 to which the target amplitude command value _Vref is input is connected to the light emitting element current control unit 11.

The light from the light emitting element 1 is configured to be received by first and second light receiving elements 2 and 3 arranged at a predetermined interval from each other. Is a fixed resistor 13 for adjusting the level of the output signal,
14 are connected.

The first and second output signals 2A and 3A, which are composed of sinusoidal signals output from the respective light receiving elements 2 and 3 and have different phases, are input terminals of an amplifier 4 composed of an operational amplifier having a fixed resistor 15. 5 and 6,
The amplifier 4 is configured to output a sine wave signal 10 having a predetermined amplitude value amplified by this. The sine wave signal 10 is output from the amplifier 4, and the amplitude value of the sine wave signal 10 is calculated by the amplitude calculation circuit 20.
0A is input to one input terminal 12a of the comparator 12.

The above-described configuration of FIG. 1 is equivalently shown in FIG. 2 as a block diagram, and has a target amplitude command value V _ref.
Is input to the comparator 12 to which the target amplitude command value _Vref and the amplitude value 20A are calculated. A comparison is made. The comparison output 12c of the comparator 12 is applied to the light emitting element current control unit 11 composed of a driving element, and the light emitting element 1 is driven in a state where the applied current is controlled, the light emitting elements 2 and 3 emit light, and the light emitting element 1 The light receiving elements 2 and 3 receive light via the rotation code plate 30 existing between the light receiving elements 2 and 3. The amplitude of the sine wave signal 10 received and output by each of the light receiving elements 2 and 3 is constantly controlled so as to become the target amplitude command value _Vref .

The configuration shown in FIG. 3 shows another embodiment of the present invention, and a case where the present invention is applied to a magnetic encoder different from the above-described optical encoder will be described.
The same or equivalent parts as those in FIG. 1 will be described using the same reference numerals. That is, what is indicated by reference numeral 50 in FIG. 3 is a magnetic gear made of a magnetic material, and a first gear made of a magnetoresistive element or the like is provided near the magnetic gear 50 at a distance from each other. , The second magnetic sensors 51 and 52 are arranged in series.

One end of the second magnetic sensor 52 is grounded, and one end of the first magnetic sensor 51 is connected to the amplifier 4 composed of an operational amplifier. An amplifier 53 and a comparator 12 are connected in series to the amplifier 4.
Of the magnetic sensors 51 and 52
Is the amplitude value 20A from the connected amplitude calculation circuit 20 to the connection point 54 of the input, the target amplitude command value V _ref is input to the second input terminal 12b of the comparator 12.

Therefore, in the configuration of FIG. 3 described above, the rotation of the magnetic gear 50 causes the first and second magnetic sensors 51 and 52 to output a sinusoidal sine wave signal 10 due to the unevenness of the teeth. . The amplitude of the sine wave signal 10 is calculated by the amplitude calculation circuit 20, and the detected amplitude value 20A is input to the first input terminal 12a of the comparator 12, and the target amplitude command value V is set in the comparator 12b. Compared to _ref .

The comparison output 12c from the comparator 12 is amplified by the amplifier 4 via the amplifying element 53 and input to the first and second magnetic sensors 52. Therefore, the sine wave signal 10
When the amplitude equal to or larger than the preset amplitude is generated, it is effectively subtracted in the comparator 12 as in the configuration of FIG. 1, the amplification factor of the amplifier 4 is controlled, and the output is output from each of the magnetic sensors 51 and 52. The amplitude of the sine wave signal 10 is equal to the target amplitude command value V
It is always controlled so as to be the same as the amplitude of _ref .

[0015]

The method for correcting the amplitude of an encoder signal according to the present invention is configured as described above, so that the following effects can be obtained. That is, in the case of an optical encoder, by controlling the amplitude detection value of the output signal output from the light receiving element to a comparator in a closed loop, the sine wave signal is controlled to become a target amplitude command value, and the amplitude of the encoder signal is adjusted. The value can be automatically controlled without using a conventional variable resistor. Also in the case of a magnetic encoder, the amplitude detection value obtained by calculating the amplitude of the output sine wave signal is closed-loop fed back to control the level of the applied voltage supplied to each magnetic sensor, and the amplitude value of the encoder signal Can be automatically controlled without using a conventional variable resistor. Therefore, regardless of the type of encoder, it is possible to control the amplitude of the encoder signal with high accuracy at a constant value, and to greatly improve the accuracy of the digital encoder signal after A / D conversion.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a method for correcting the amplitude of an encoder signal according to the present invention.

FIG. 2 is a block diagram showing the equivalent of FIG. 1;

FIG. 3 is a circuit diagram showing another embodiment of FIG. 1;

FIG. 4 is a circuit diagram showing a conventional method for correcting the amplitude of an encoder signal.

[Explanation of symbols]

Reference Signs List 1 light emitting element 2, 3 light receiving element 2A, 3A output signal 4 amplifier 10 sine wave signal 11 light emitting element current control unit 12 comparator 20 amplitude calculation circuit 20A amplitude detection value 50 magnetic gear body 51, 52 magnetic sensor V _ref target amplitude command value

Claims (2)

[Claims] 1. A rotary code plate (30) for transmitting light from a light emitting element (1).
The light receiving element (2, 3) receives the light, and the output signal (2A, 3A) obtained from the light receiving element (2, 3) is amplified via an amplifier (4) to generate a sine wave signal (10). And the sine wave signal (10)
In the amplitude correction method of an encoder signal configured to correct the amplitude of the output signal (2A, 3A), an amplitude detection value (20A) obtained by calculating the amplitude of the output signal (2A, 3A) is used to drive the light emitting element (1). A method of correcting the amplitude of an encoder signal, wherein a feedback input is provided to a comparator (12) provided before a device current controller (11) and to which a target amplitude command value (V _ref ) has been input. 2. A magnetic gear (50) is rotated in a state where an applied voltage is supplied to the magnetic sensors (51, 52) via an amplifier (4), and the magnetic sensors (51, 52) are rotated by the magnetic sensor (51, 52). A method of obtaining a sine wave signal (10) corresponding to the shape of (50) and correcting the amplitude of the sine wave signal (10), wherein the amplitude of the sine wave signal (10) is corrected. The amplitude detection value (20A) obtained by calculating the target amplitude command value (V) provided before the amplifier (4) that generates the applied voltage
amplitude correction method of an encoder signal, characterized in that the _{comparator ref)} is input to the (12), and feedback input.