Reflection type photoelectric encoder air gap tolerance optimization method

Abstract

The invention provides an air gap tolerance optimization method for a reflective photoelectric encoder. The device is characterized by comprising an LED module (1), a photodiode array (2), a coded disc (3) and a current adjusting circuit (4). The LED module is composed of two LEDs of the same model, and the two LEDs are an LED 1 and an LED 2 respectively. The photodiode array is composed of an incremental code channel photodiode array (21) and light intensity indication photodiodes (22), the light intensity indication photodiodes are two identical photodiodes (PD1 and PD2), the incremental code channel photodiode is composed of two groups of PD arrays (PD3 and PD4), and the current adjusting circuit (4) is composed of a quaternion amplification circuit (41) and a current control circuit (42). The method can be applied to air gap tolerance optimization of the reflective photoelectric encoder, and can be widely applied to the fields of industrial production, aerospace, medical treatment, precise instruments, experimental scientific research, numerical control machine tools and the like.

Description

(I) Technical field

[0001] The present invention relates to a reflective photoelectric encoder air gap tolerance optimization method, which can be widely used in medical positioning, laboratories, navigation, aerospace, industrial automation, robotics, CNC machine tools and other fields, belonging to the field of photoelectric encoder technology. (II) Background technology

[0002] Reflective photoelectric encoder is a sensor widely used in position detection and motion control. Its working principle is based on photoelectric conversion technology. This device usually uses optical principles to achieve high-precision position measurement and converts the measurement results into digital signals for further processing by computers or control systems. With the development of modern industry and automation technology, the demand for high-precision position detection equipment is increasing. Reflective photoelectric encoders have attracted widespread attention in many fields due to their superior performance, especially in automated production lines, robotics, aerospace, and precision manufacturing. Its application prospects are particularly broad.

[0003] The core working principle of the reflective photoelectric encoder is to rely on the emission of light sources and signal reception. When the transmitter in the encoder emits light, the light is reflected by the surface of the target object back to the photodetector, which converts the received reflected light signal into an electrical signal to measure the position of the target object. The advantage of this measurement method is its high precision and non-contact characteristics, which enables the encoder to accurately locate and monitor motion without interfering with the object being measured.

[0004] However, in the actual application of reflective photoelectric encoders, the air gap (i.e., the distance between the encoder and the target object) accuracy is extremely high. Changes in the air gap will directly affect the intensity and quality of the light signal. Therefore, reflective photoelectric encoders usually require a very small air gap tolerance, usually only a few hundred microns. This accuracy requirement has, to some extent, limited the application areas of the encoder and increased the cost and complexity of air gap control. For example, in many environments with high-precision measurement requirements, the movement and position detection of the equipment needs to be performed under dynamic conditions. In this case, maintaining the stability and consistency of the air gap is an extremely challenging engineering task.

[0005] In the existing technology, most reflective photoelectric encoders generally use a single LED for light signal collection. The use of a single light source causes the intensity of the light signal received by the photodetectors at different positions to vary unevenly, making it impossible to uniformly amplify the signal. This uneven light signal reception limits the size of the air gap to a very small range, and the air gap tolerance becomes extremely small. In addition, due to possible environmental changes during use, such as temperature, humidity, and vibration, the measurement accuracy of the encoder may be greatly affected, making the changes in the light signal more complicated, further exacerbating the difficulty of controlling the air gap accuracy.

[0006] In order to solve these problems, the present invention proposes a new air gap tolerance optimization method for reflective photoelectric encoders. The optimization method adopts symmetrical LED position placement and uniformly adjusts the optical power of two groups of LEDs through current control of the light intensity recognition photodiode connection. Through this design, the light intensity of the light signal received on the incremental code channel photodiode can change synchronously when the air gap changes, thereby significantly increasing the air gap tolerance of the reflective photoelectric encoder. Specifically, the symmetrical placement of LEDs in the encoder structure can ensure that when the air gap changes, the light signals emitted by the two LEDs are evenly distributed to the photodetector. This uniform light intensity distribution not only improves the signal-to-noise ratio of the signal, but also reduces the measurement error caused by the air gap change, so that the reflective photoelectric encoder can work in a wider range of air gaps. In addition, this method also improves the quality of the output signal, so that the encoder can provide stable and reliable position information under different air gap conditions. The synchronization of light intensity changes ensures that the response speed of the system under dynamic working conditions is also significantly improved, so that the encoder can better adapt to high-speed mobile application scenarios. This innovation combines advanced engineering design and optical technology to make significant progress in high-precision and high-reliability photoelectric measurement for reflective photoelectric encoders. For example, in the aerospace field, 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, reflective photoelectric encoders will also become an important tool for achieving efficient production. (III) Summary of the invention

[0007] The object of the present invention is to provide a method for optimizing the air gap tolerance of a reflective photoelectric encoder, wherein the system involved in the method comprises an LED module (1), a photodiode array (2), a code disk (3), and a current regulating circuit (4). The LED module comprises two LEDs of the same model, namely LED1 and LED2; the photodiode array comprises an incremental code channel photodiode array (21) and a light intensity indicating photodiode (22), the light intensity indicating photodiode is two completely identical photodiodes, namely PD1 and PD2; the incremental code channel photodiode comprises two groups of PD arrays, namely PD3 and PD4; and the current regulating circuit (4) comprises a quartz resistance amplifier circuit (41) and a current control circuit (42).

[0008] The object of the present invention is achieved in that:

[0009] LED1 and LED2 are symmetrically arranged on the reflective photoelectric encoder chip with the chip center as the symmetrical point. The incremental code channel photodiode (21) receives the light signal emitted by the LED module (1) and reflected by the code disk (3) at the middle position between LED1 and LED2. The light intensity indication photodiode (22) is placed at symmetrical positions on both sides of the LED module (1) near the outside of the reflective photoelectric encoder chip and is lower than the LED module (1). After the light emitted by the LED module (1) is irradiated to the light intensity indication photodiode (22), it is converted into a voltage signal through the quartz-resistance amplifier circuit (41). The voltage signal is transmitted to the current control circuit (42) to adjust the current of the LED module (1) so that the light power output by LED1 and LED2 is equal to the preset light power. The light signal emitted by the LED module (1) is reflected to the incremental code channel photodiode (2) via the code disk (3). Since the LED module (1) is relative to the code disk (3), The LED modules (1) are arranged symmetrically and the optical power of the LED module (1) is adjusted to be consistent, so the light intensity distribution on the incremental code channel photodiode (21) is nearly uniform; when the air gap changes, since PD1 and PD2 are located between LED1 and LED2, PD1 and PD2 receive the light from LED1 and LED2 at the same time. Since LED1 and LED2 are symmetrical, the light signals reflected back are also symmetrical. After being superimposed on PD1, the light intensity distribution of the light signal changes to a uniform distribution in the Y direction, and the light signal is greatly optimized. Due to the symmetry, the light intensity on PD1 and PD2 is completely consistent. When the air gap changes, the light intensity on PD1 and PD2 is always consistent, and the PD signal can be amplified using the same gain multiple, thereby overcoming the disadvantage of the traditional single-LED reflective photoelectric encoder that when the air gap increases, the amplitude of the light signal received by the PD farther away from the LED decreases much more than that of the other PD, thereby greatly increasing the tolerance for the air gap.

[0010] The light beam emitted by the LED module (1) may be light of various wavelengths such as infrared light, blue light, red light, etc. The specific light source to be used should be determined according to the light sensitivity of the photodiode used.

[0011] The light intensity indicating photodiode (22) is used to receive the light intensity emitted by the LED module (1). Since the performance of LEDs varies after leaving the factory, there are differences in light power under the same current. The light intensity indicating photodiode (22) receives the light emitted by the LED module (1), and the photocurrent is converted into a voltage signal that can be used for comparison through the quartz-resistance amplifier circuit (41). Finally, the power supply current of LED1 and LED2 is adjusted to their light powers are exactly the same through the current control circuit (42), which can effectively optimize the light power difference problem caused by the dual LEDs.

[0012] The LED modules (1) are symmetrically distributed on the reflective photoelectric encoder chip, so that the light signals emitted by LED1 and LED2 are symmetrical when reflected by the code disk (3) to the incremental code channel photodiode (2), and after the light signals are superimposed, the light signals received by the incremental code channel photodiode (2) are uniform in the Y direction.

[0013] According to the method for optimizing the air gap tolerance of a reflective photoelectric encoder according to claim 1, it is characterized in that: the LED module (1) is symmetrically distributed on the reflective photoelectric encoder chip and the current is adjusted by the current control circuit (4), so that the amplitude of the optical signal received on PD1 and PD2 is the same, and when the air gap changes, the amplitude change value of the optical signal on PD1 and PD2 is also equal. (IV) Description of the drawings

[0014] Figure 1 The invention is composed of an LED module (1), a photodiode array (2), a code disk (3), and a current regulating circuit (4). The LED module is composed of two LEDs of the same model, namely LED1 and LED2; the photodiode array is composed of an incremental code channel photodiode array (21) and a light intensity indicating photodiode (22); the light intensity indicating photodiode is two completely identical photodiodes, namely PD1 and PD2; the incremental code channel photodiode is composed of two groups of PD arrays, namely PD3 and PD4; and the current regulating circuit (4) is composed of a quartz resistance amplifier circuit (41) and a current control circuit (42).

[0015] Figure 2 This is the light spot distribution diagram in the reflective photoelectric encoder example. The first one on the left is the light spot distribution diagram after the air gap continues to decrease relative to the original minimum position, and the second one on the left is the light spot distribution diagram after the air gap continues to increase relative to the original maximum air gap. It can be observed that the distribution of light signals in the Y direction is nearly uniform.

[0016] Figure 3 It is the output signal of the reflective photoelectric encoder and the standard sinusoidal signal. 1 is the standard sinusoidal signal, 2 is the output signal after the air gap exceeds the original maximum air gap and continues to increase, and 3 is the output signal after the air gap exceeds the original minimum air gap and continues to decrease.

[0017] Figure 4 It is a specific image of the placement of various components on the surface of a reflective photoelectric encoder chip, wherein the surface components are composed of an LED module (1) and a photodiode array (2). The LED module is composed of two LEDs of the same model, namely LED1 and LED2; the photodiode array is composed of an incremental code channel photodiode array (21) and a light intensity indication photodiode (22), wherein the light intensity indication photodiode is two completely identical photodiodes, namely PD1 and PD2, and the incremental code channel photodiode is composed of two groups of PD arrays, namely PD3 and PD4. (V) Specific implementation methods

[0018] Embodiment 1: Figure 1An embodiment of a method for optimizing the air gap tolerance of a reflective photoelectric encoder is provided. The method for optimizing the air gap tolerance of a reflective photoelectric encoder comprises an LED module (1), a photodiode array (2), a code disk (3), and a current regulating circuit (4). The LED module comprises two LEDs of the same model, namely LED1 and LED2; the photodiode array comprises an incremental code channel photodiode array (21) and a light intensity indicating photodiode (22), the light intensity indicating photodiode is two completely identical photodiodes, namely PD1 and PD2; the incremental code channel photodiode comprises two groups of PD arrays, namely PD3 and PD4; the current regulating circuit (4) comprises a quartz resistance amplifier circuit (41) and a current control circuit (42); LED1 and LED2 are symmetrically arranged on a reflective photoelectric encoder chip with the chip center as the symmetrical point. The light signals emitted by LED1 and LED2 are received by PD1 and PD2 respectively. After receiving the light signals, PD1 and PD2 generate photocurrents, which are respectively input into the quartz-resistance amplifier circuit (41) to be converted into voltage signals. The voltage signals corresponding to PD1 and PD2 are then respectively input into the current control circuit (42) to adjust the light emitting power of LED1 and LED2 to a preset value. Through this step, the light emitting power of LED1 and LED2 is made consistent. The LEDs in the LED module (1) are symmetrically arranged so that the light signals emitted by the two groups of LEDs are reflected back by the code disk (3). When the reflective photoelectric encoder chip is mounted on the encoder disk (3), the light signal received by the incremental code channel photodiode (21) is two groups of light signals with exactly the same X-axis distribution and opposite Y-axis distribution. The light signal of a single group of LEDs can be fitted as a linear straight line in the Y-axis direction. When the light signals emitted by the two groups of LEDs are superimposed on the same PD, the light signal received on the PD becomes uniformly distributed in the Y direction. Since PD3 and PD4 are between LED1 and LED2, and since the luminous powers of LED1 and LED2 are set to the same value, the amplitudes of the light signals superimposed on PD3 and PD4 are also the same. At this time, the air gap between the reflective photoelectric encoder chip and the code disk (3) is reduced. At this time, the light signal received on the incremental code channel photodiode (21) is distributed as follows: Figure 2 On the other hand, if the air gap between the reflective photoelectric encoder chip and the code disk (3) is increased, the distribution of the optical signal received by the incremental code channel photoelectric encoder (21) is as follows: Figure 2 As shown in the second figure on the left, it can be observed from the picture that when the air gap changes, the optical signal on the incremental code channel photodiode (21) is a high-quality uniform light spot, and the output signal output by this optical signal is as follows: Figure 3As shown in the signals 2 and 3 in the figure, it can be observed that there are only slight differences between the signals 2 and 3 and the standard sinusoidal signals, and the output signal quality is excellent. In summary, the photoelectric encoder of this embodiment achieves high-precision and high-reliability photoelectric measurement through innovative design and engineering technology. This photoelectric encoder based on a symmetrical LED module, due to its symmetrical structural layout, enables flexible response to external environmental changes during the optical signal processing process, and is particularly suitable for a wide range of applications in the fields of industrial automation, robotics, and high-end photoelectric measurement. The present invention not only provides an effective solution to the problems encountered by traditional photoelectric encoders in applications, but also opens up new horizons and directions for the development of related technical fields.

Claims

1. A method for optimizing the air gap tolerance of a reflective photoelectric encoder. The method is characterized by: The invention is composed of an LED module (1), a photodiode array (2), a code disk (3), and a current regulating circuit (4). The LED module is composed of two LEDs of the same model, namely LED1 and LED2; the photodiode array is composed of an incremental code channel photodiode array (21) and a light intensity indicating photodiode (22), the light intensity indicating photodiode is two completely identical photodiodes, namely PD1 and PD2, the incremental code channel photodiode is composed of two groups of PD arrays, namely PD3 and PD4, the current regulating circuit (4) is composed of a quartz resistance amplifier circuit (41) and a current control circuit (42); LED1 and LED2 are symmetrically arranged on the reflective photoelectric encoder chip with the center of the chip as the symmetrical point, and the incremental code channel photodiode ( 21) receiving the light signal emitted by the LED module (1) and reflected by the code disk (3) at the middle position between LED1 and LED2, the light intensity indicating photodiode (22) is placed at the symmetrical position on both sides of the LED module (1) near the outside of the reflective photoelectric encoder chip, and the position is lower than the LED module (1), after the light emitted by the LED module (1) irradiates the light intensity indicating photodiode (22), it is converted into a voltage signal through the quartz-resistance amplifier circuit (41), and the voltage signal is transmitted to the current control circuit (42) to adjust the current of the LED module (1), so that the light power output by LED1 and LED2 is the preset light power and is equal; The light signal emitted by the LED module (1) is reflected by the code disk (3) to the incremental code channel photodiode (2). Since the LED module (1) is symmetrically arranged relative to the code disk (3) and the light power of the LED module (1) is adjusted to be consistent, the light intensity distribution on the incremental code channel photodiode (21) is nearly uniform. When the air gap changes, since PD1 and PD2 are located between LED1 and LED2, PD1 and PD2 receive the light from LED1 and LED2 at the same time. Since LED1 and LED2 are symmetrical, the light signal reflected back by them is It is also symmetrical. After being superimposed on PD1, the light intensity distribution of its optical signal changes to a uniform distribution in the Y direction, and the optical signal is greatly optimized. Due to the symmetry, the light intensity on PD1 and PD2 is completely consistent. When the air gap changes, the light intensity on PD1 and PD2 always remains consistent, and the PD signal can be amplified using the same gain multiple, overcoming the disadvantage of the traditional single-LED reflective photoelectric encoder that when the air gap increases, the amplitude of the received optical signal of the PD farther away from the LED decreases much more than that of the other PD, greatly increasing the tolerance for the air gap.

2. The air gap tolerance optimization method of the reflective photoelectric encoder according to claim 1 is characterized in that: The light beam emitted by the LED module (1) may be infrared light, blue light, red light or other light having a wavelength suitable for PD reception.

3. The air gap tolerance optimization method of the reflective photoelectric encoder according to claim 1; characterized in that: The light intensity indicating photodiode (22) is used to receive the LED module (1) and instruct the current control circuit (42) to adjust the current of the LED module so that the output light power of LED1 and LED2 is the same.

4. The air gap tolerance optimization method of the reflective photoelectric encoder according to claim 1, characterized in that: The LED module (1) is symmetrically distributed relative to the incremental code tracks on the code disk, so that the light passing through it is symmetrical when it is reflected from the code disk (3) to the incremental code track photodiode (2). After the light spots are superimposed, the light signal received by the incremental code track photodiode (2) is uniform in the Y direction.

5. The method for optimizing the air gap tolerance of a reflective photoelectric encoder according to claim 1, characterized in that: The LED module (1) has a symmetrical distribution of incremental code tracks on a relative code disk, so that the amplitudes of the optical signals received on PD1 and PD2 are the same, and when the air gap changes, the amplitude changes of the optical signals on PD1 and PD2 are also equal.

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