Real-time cancellation system for optical encoder cross-talk signals

Abstract

The present application provides a photoelectric encoder crosstalk signal real-time reduction system. Its features are: composed of photodiode array, amplifier circuit, reduction circuit, attenuation circuit, coefficient adjustment system; wherein the photodiode array is composed of incremental code channel photodiode array and absolute code channel photodiode array, the incremental code channel photodiode array is composed of each group of photodiode, the coefficient adjustment system is composed of potentiometer circuit, peak-to-peak value detection circuit and comparator circuit; the absolute code channel directly opposite the incremental code channel photodiode array is called A array, and the array with a phase difference of 180° from the A array is called B array. The present application can be applied to signal repair when the light signals between each code channel of the photoelectric encoder interfere with each other, and can be widely applied to industrial production, aerospace, medical treatment, precision instruments, experimental research, numerical control machine tools and other fields.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of photoelectric encoder aliasing signal real-time reduction system, can be widely used in medical positioning, laboratory, marine industry, aerospace, industrial automation, robot technology, numerical control machine tool etc.Field.Belongs to photoelectric encoder technical field. BACKGROUND

[0002] Photoelectric encoder is a kind of precision measuring equipment widely used in industrial automation, robot technology and aerospace etc.Field, its basic principle is by light source (such as LED) emits light, utilizes the specific optical pattern (transparent and opaque area) on encoding disc or strip to modulate light, and then by photoelectric sensor converts light signal into electrical signal, to realize the high-precision measurement of rotation angle or linear displacement.Photoelectric encoder is mainly divided into incremental encoder and absolute encoder two types, incremental encoder outputs the relative change of displacement, relies on displacement pulse counting to judge position, cannot determine absolute position after power failure;And absolute encoder is assigned a unique digital code for each position, even in the case of power failure, the current position can be accurately identified.This unique design makes photoelectric encoder particularly important in applications requiring high precision and reliability, such as automated production lines, robot operation, and aerospace etc.Field.

[0003] With the continuous progress of technology, the performance and function of photoelectric encoder are also constantly improved, especially in the development background of optical sensor and digital signal processing technology, the resolution, accuracy and reliability of photoelectric encoder have been significantly improved.Modern photoelectric encoder also begins to integrate multiple communication interfaces, enhances the interconnectivity and intelligent characteristics with other devices.The future development trend of photoelectric encoder will focus on higher integration, intelligentization and wireless technology application, to adapt to the needs of mobile devices and complex industrial environments.At the same time, the adaptability to high temperature, dust and harsh environment will also be valued, to improve its performance in challenging environment.In addition, the improvement of human-computer interaction interface will make the operation of encoder more intuitive and convenient, further promote photoelectric encoder to play a more important role in intelligent manufacturing and industry 4.0 era.

[0004] However, in the actual application of photoelectric encoder, limited to the size of actual code disc, there is often only a few hundred microns distance between each code channel, and the collimation degree of actual light source is limited to existing technology and cannot achieve complete collimation, still there will be divergence angle, which leads to the light signal of each code channel will superimpose each other, so that light signal aliasing, finally the output signal also exists serious distortion, has great influence on the actual performance of photoelectric encoder.

[0005] In the prior art, the method for mutual crosstalk of optical signals is usually to shorten the width of the code channel, but this method reduces the intensity of the already weak optical signal, greatly reduces the stability of the chip signal, and has a small tolerance. Due to process differences, there are also performance differences between actual same type light sources. When the light source intensity is too large, there will still be some crosstalk.

[0006] To solve these problems, the present application proposes a new photoelectric encoder crosstalk signal reduction system. The application sets up a specific phase difference photodiode array on the incremental code channel, so that the crosstalk signal appears at a fixed phase position. Then, through the reduction of the reduction circuit, the crosstalk signal on the incremental code channel photodiode can be reduced. After obtaining the crosstalk-free signal of the incremental code channel, the peak-to-peak value intensity of each code channel as designed initially is obtained. Then, the signal is multiplied by the coefficient through the potentiometer circuit to reduce the absolute code channel (other code channels), and the reduction coefficient is controlled through the comparator circuit until the crosstalk signal is completely reduced. Through this design, real-time reduction of the photoelectric encoder crosstalk signal is realized. In addition, this method also improves the quality of the output signal, so that the photoelectric encoder can adapt to the light intensity distribution when using light sources with different performance, and the encoder can better adapt to different application scenarios. This innovation combines advanced engineering design and optical technology, and makes significant progress in photoelectric measurement with high precision and high reliability. For example, in the field of aerospace, accurate position detection is crucial, and the optimized encoder can ensure the stability and safety of the aircraft under complex environmental conditions. In industrial automation, with the continuous development of intelligent manufacturing, photoelectric encoders will become an important tool for efficient production. SUMMARY

[0007] The purpose of the present application is to provide a photoelectric encoder crosstalk signal real-time reduction system. This method involves a system composed of a photodiode array, a quorum amplification circuit, a reduction circuit, an attenuation circuit, and a coefficient adjustment system. The photodiode array is composed of an incremental code channel photodiode array and an absolute code channel photodiode array. The incremental code channel photodiode array is composed of groups of photodiodes. The coefficient adjustment system is composed of a potentiometer circuit, a peak-to-peak value detection circuit, and a comparator circuit. The absolute code channel directly opposite the incremental code channel photodiode array is called A array, and the array with a phase difference of 180° from the A array is called B array.

[0008] The purpose of the present application is achieved as follows:

[0009] When the photoelectric encoder is in normal operation, the photoelectric diode array receives the light signal, the incremental code channel photoelectric diode array receives the sinusoidal signal, and due to the close distance between the code channels, the incremental code channel photoelectric diode array will simultaneously receive the light signal of the absolute code channel, that is, the crosstalk signal. The incremental code channel photoelectric diode array converts the received light signal into a photoelectric current and inputs the photoelectric current into a quorum amplification circuit. The A array signal and the B array signal correspond to the A signal and the B signal, respectively. Then the A signal and the B signal are input into a subtraction circuit to obtain an output signal C from A-B. Since the original signals of A and B are sinusoidal signals with a phase difference of 180° and crosstalk signals, the crosstalk signals are at the top of the A signal and the bottom of the B signal, respectively. Therefore, the C signal obtained after the subtraction circuit is a sinusoidal signal with twice the amplitude. The C signal is input into an attenuation circuit to attenuate the amplitude to one half of the original amplitude. The C signal is restored to the A signal without crosstalk, which is called A+ signal. The signal received by the absolute code channel photoelectric diode array is called Z signal. The original signal of the Z signal is a pulse signal, which is crosstalked by a sinusoidal signal with the same frequency as the A signal but smaller amplitude. The A+ signal is input into a potentiometer circuit, and the output signal is input into the subtraction circuit together with the Z signal to obtain the subtracted Z+ signal. The Z+ signal and the A+ signal are input into a peak-to-peak value detection circuit to identify the peak-to-peak value. The corresponding signal is input into a comparator circuit. The feedback signal is obtained by comparing the sizes of A+ and Z+. When the peak-to-peak value of Z+ is greater than A+, the feedback signal is output to the potentiometer circuit to increase the subtraction coefficient of A+. When A+ is equal to or less than Z+, the feedback signal is stopped. At this time, the original Z signal without crosstalk signal can be obtained by the formula Z+ = Z- coefficient * A+ in the subtraction circuit.

[0010] The incremental code channel photoelectric diode array is designed with a specific phase difference, so that the crosstalk signal appears at the top of the A signal and the bottom of the B signal. Since the original signals of A and B are sinusoidal signals with the same amplitude, the crosstalk signals are canceled by subtraction, and the subtraction of A and B signals becomes the original signal with twice the amplitude.

[0011] The coefficient adjustment system adjusts the subtraction coefficient in real time through the potentiometer circuit based on the comparison of the peak-to-peak values of A+ and Z+ signals.

[0012] The reduction circuit reduces the crosstalk problem of the photodiode output signal caused by the mutual interference of the optical signals through a specific formula and adjusting the coefficients in the formula. Due to the process and preservation problems, there are individual differences in the actual use of the light source, and the differences are very large, so the coefficient of the real-time reduction of the crosstalk signal needs to be adjusted in real time according to the intensity and light signal distribution of the actual light source. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is the structure and flow chart of the photoelectric encoder crosstalk signal real-time reduction system, which is composed of a photodiode array, a buffer amplifier circuit, a reduction circuit, an attenuation circuit, and a coefficient adjustment system; the photodiode array is composed of an incremental code channel photodiode array and an absolute code channel photodiode array, the incremental code channel photodiode array is composed of each group of photodiodes, the coefficient adjustment system is composed of a potentiometer circuit, a peak-to-peak value detection circuit, and a comparator circuit; the absolute code channel photodiode array opposite to the incremental code channel photodiode array is called A array, the array with a phase difference of 180° from the A array is called B array, the output signal of the A array is A signal, the output of the B array is B signal, the output signal of the absolute code channel photodiode is Z signal, the output signal of the A and B signals after the reduction circuit is C signal, the output signal of the C signal after the attenuation circuit is A+ signal, and the output signal of the Z signal and A+ signal after the reduction circuit is Z+ signal.

[0014] Figure 2 is the output signal image of the incremental code channel photodiode array output signal affected by crosstalk, the signal affected by the crosstalk signal at the top is A signal, and the signal affected by the crosstalk signal at the bottom is B signal.

[0015] Figure 3 is the output signal image of the absolute code channel photodiode array output signal affected by crosstalk.

[0016] Figure 4 is the actual output signal image after reduction, the sinusoidal signal is A+ signal, and the pulse signal is Z+ signal. DETAILED DESCRIPTION

[0017] Example One: Figure 1The specific structure and flowchart of the embodiment are given, and the real-time reduction system of the crosstalk signal of the photoelectric encoder is composed of a photodiode array, a resistance-capacitance amplification circuit, a reduction circuit, an attenuation circuit, and a coefficient adjustment system; wherein the photodiode array is composed of an incremental code channel photodiode array and an absolute code channel photodiode array, the incremental code channel photodiode array is composed of groups of photodiodes, the coefficient adjustment system is composed of a potentiometer circuit, a peak-to-peak value detection circuit, and a comparator circuit; the incremental code channel photodiode array above the absolute code channel is called A array, and the array with a phase difference of 180° from the A array is called B array; when the photoelectric encoder is normally operated, the incremental code channel photodiode array receives a sinusoidal signal, due to the close distance between the code channels, the incremental code channel photodiode array will simultaneously receive the light signal of the absolute code channel, that is, the crosstalk signal, the incremental code channel photodiode array converts the received light signal into a photoelectric current, and inputs the photoelectric current into the resistance-capacitance amplification circuit, the A array signal and the B array signal correspond to A signal and B signal respectively, then the A signal and the B signal are input into the reduction circuit, and the output signal C is obtained by subtracting the B signal from the A signal, since the original signals of A and B are sinusoidal signals with a phase difference of 180° plus crosstalk signals (such as Figure 2 ), and the crosstalk signals are respectively at the top of the A signal and the bottom of the B signal, therefore, the C signal obtained after the reduction circuit is a sinusoidal signal with twice the amplitude, the C signal is input into the attenuation circuit to attenuate the amplitude to half of the original, the C signal is restored to the A signal without crosstalk, which is called A+ signal; the signal received by the absolute code channel photodiode array is called Z signal, the original signal of the Z signal is a pulse signal, which is disturbed by a sinusoidal signal with the same frequency as the A signal but smaller amplitude (such as Figure 3 ), the A+ signal is input into the potentiometer circuit, and the output signal is input into the reduction circuit together with the Z signal to obtain the reduced Z+ signal, the Z+ signal and the A+ signal are input into the peak-to-peak value detection circuit to identify the peak-to-peak values, and the corresponding signals are input into the comparator circuit, the feedback signal is obtained by comparing the sizes of A+ and Z+, when the peak-to-peak value of Z+ is greater than A+, the feedback signal is output to the potentiometer circuit to increase the reduction coefficient of A+, when A+ is equal to or less than Z+, the feedback signal is stopped, and at this time, the original Z signal without crosstalk signal influence can be obtained through the formula Z+ = Z-coefficient*A+ in the reduction circuit (such as Figure 4 ). Through this design, the intensity of the light signal is monitored in real time and the reduction coefficient is dynamically adjusted, the signal affected by crosstalk is effectively reduced, and the overall performance of the photoelectric encoder under different light source conditions is significantly improved; this design not only enhances the signal quality and improves the signal-to-noise ratio, but also enables the photoelectric encoder to adapt to various light intensities and light signal distributions, and is widely used in automatic production, medical equipment, outdoor detection and other fields, thereby expanding the application scenarios and improving the reliability and accuracy of operation.

Claims

1. A real-time interference signal reduction system for photoelectric encoders, characterized in that: It consists of a photodiode array, a cross-impedance amplifier circuit, a subtraction circuit, an attenuation circuit, and a coefficient adjustment system. The photodiode array comprises an incremental code track photodiode array and an absolute code track photodiode array. The incremental code track photodiode array is composed of various groups of photodiodes. The coefficient adjustment system consists of a potentiometer circuit, a peak-to-peak detection circuit, and a comparator circuit. The incremental code track photodiode array directly above the absolute code track is called array A, and the array with a 180° phase difference from array A is called array B. During normal operation of the photoelectric encoder, the incremental code track photodiode array receives a sinusoidal signal. Due to the close proximity of the code tracks, the incremental code track photodiode array simultaneously receives the optical signal from the absolute code track. The interfering signal is the received optical signal converted into photocurrent by the incremental code channel photodiode array, which is then input to the cross-impedance amplifier circuit. The A array signal and the B array signal correspond to the A signal and the B signal, respectively. The A signal and the B signal are then input to the subtraction circuit. The B signal is subtracted from the A signal to obtain the output signal C. Since the original signals A and B are sinusoidal signals with a phase difference of 180° plus the interfering signal, and the interfering signal is located at the top of the A signal and the bottom of the B signal, the C signal obtained after the subtraction circuit is a sinusoidal signal with twice the amplitude. The C signal is input to the attenuation circuit to attenuate the amplitude to half of the original value, and the C signal is restored to the A signal without interfering, which is called the A+ signal. The signal received by the absolute code channel photodiode array is called the Z signal. The original Z signal is a pulse signal, which is interfered with by a sinusoidal signal with the same frequency as the A signal but a smaller amplitude. The A+ signal is input to the potentiometer circuit, and the output signal is then input together with the Z signal to the subtraction circuit to obtain the subtracted Z+ signal. The Z+ signal and the A+ signal are input to the peak-to-peak detection circuit to identify their peak-to-peak values. The corresponding signals are then input to the comparator circuit. By comparing the magnitudes of the A+ and Z+ signals, a feedback signal is obtained. When the peak-to-peak value of Z+ is greater than that of A+, the feedback signal is output to the potentiometer circuit to increase the subtraction coefficient of A+. When A+ is equal to or less than the Z+ signal, the feedback signal is stopped. At this time, the Z signal can be obtained by using the formula Z+ = Z - coefficient * A+ in the subtraction circuit, so that the original Z signal unaffected by the interference signal can be obtained.

2. The real-time interference signal reduction system for photoelectric encoders according to claim 1; characterized in that: The incremental code channel photodiode array, through its phase difference positioning design, enables the subtraction of crosstalk signals in signal A after subtracting signal B from signal A.

3. The real-time interference signal reduction system for photoelectric encoders according to claim 1; characterized in that: The coefficient adjustment system transforms the subtraction of crosstalk signals into a comparison of the peak-to-peak values ​​of the A+ and Z+ signals through peak-to-peak detection and comparator circuits, and adjusts the subtraction coefficient in real time through potentiometer circuits.

4. The real-time interference signal reduction system for photoelectric encoders according to claim 1; characterized in that: The subtraction circuit uses a formula and adjusts the coefficients in the formula to reduce the crosstalk problem of the photodiode output signal caused by mutual interference of optical signals.

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