A photodiode array with area compensation

Abstract

The present invention relates to a photodiode array with area compensation, characterized in that the photodiode array includes a plurality of main photodiodes with large areas and a plurality of compensation photodiodes with small areas, each main photodiode and the compensation photodiodes in the same column constitute a photodiode group, and a plurality of photodiode groups are arranged in parallel to form a photodiode array, and the output signal of each compensation photodiode in the same group is connected to the output of the main photodiode in the group through a switching circuit; the areas of the main photodiodes at different positions are different, and the areas of the main photodiodes increase successively from the middle position to the two sides.

Description

Technical Field

[0001] The present invention relates to a semiconductor power device, and in particular to a photodiode array detector with area compensation for a photoelectric encoder. Background Art

[0002] With the development of science and technology, computer technology, sensor technology, communication technology, etc. are combined with each other in industrial CNC processing and automatic production lines to improve the product processing capabilities, processing accuracy and efficiency. Photoelectric encoders play a vital role in this. Photoelectric encoders have gradually developed into mature and high-performance industrial products with advantages such as high resolution, no contact error, small size, and easy maintenance. They are widely used in various industrial control occasions such as radar, aerospace, automated production lines, CNC machine tool processing and positioning, automobile speed detection, servo systems, etc.

[0003] As many fields place higher demands on the performance of photoelectric encoders, they are gradually developing towards high precision, high resolution, high reliability, and integration. Encoders have high requirements for displacement sensitivity, but due to manufacturing limitations, high-resolution encoders place higher demands on photodiode array detectors, requiring extensive design work on the layout of the photodiode array detector.

[0004] Traditional photodiode array designs generally fail to consider the impact of light intensity distribution on the output signal. Photodiodes at different locations are designed to have the same area. This design presents a problem: photodiodes farther from the light source receive relatively weaker light intensity, resulting in smaller photoelectric signals. This leads to inconsistent output signals from photodiodes at different locations, a particularly significant issue with absolute code signals. While some designs do consider the impact of light intensity distribution on the output signal, these are typically customized for a specific light source. The area of ​​photodiodes at different locations is compensated accordingly to achieve consistent output signals. However, due to factors such as material, geometry, and packaging, light sources of different types and models exhibit significant variations in light intensity distribution. Therefore, photodiode arrays designed for a specific light source cannot be universally compatible across different light sources, resulting in limited flexibility and adaptability. Consequently, when using different light sources, customized designs are required, increasing design complexity and cost. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a photodiode array structure applied to a photoelectric encoder, which can adapt to a variety of light sources with different light intensity distributions. According to the light intensity distribution characteristics of different light sources, multiple area compensations are performed on the photodiodes at each position, and each area compensation corresponds to a light source. The output signal of each compensation module is connected to the output of the main photodiode through a switching circuit. When using different types of light sources, the compensation part corresponding to the light source can be connected through the switching circuit, thereby realizing the flexibility and universality of the photodiode array chip, while adapting to different types of light sources, reducing the design complexity and design cost.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] A photodiode array with area compensation includes a plurality of main photodiodes with large areas and a plurality of compensation photodiodes with small areas. Each main photodiode and the compensation photodiodes in the same column constitute a photodiode group. Several photodiode groups are arranged in parallel to form a photodiode array. The output signal of each compensation photodiode in the same group is connected to the output of the main photodiode in the group through a switching circuit. The areas of the main photodiodes at different positions are different, and the areas of the main photodiodes increase from the middle position to the two sides.

[0008] Furthermore, the main photodiodes and the compensation photodiodes are rectangular in shape, and the main photodiodes and the compensation photodiodes in the same group have the same width and different heights.

[0009] Furthermore, a photodiode group consisting of the main photodiode and the compensation photodiode is arranged in parallel.

[0010] Furthermore, the compensation photodiodes are all located on the same side of the main photodiode, and the number of compensation photodiodes in each group is the same.

[0011] Furthermore, the compensation photodiodes are located on both sides of the main photodiode, and the number of compensation photodiodes included in each photodiode group on the same side is equal.

[0012] Furthermore, the widths of the main photodiodes are the same, and only the heights are different. The heights of the main photodiodes increase successively from the middle position to both sides, and the heights of the main photodiodes either extend only to the same side or to both sides; and the main photodiode array is axially symmetrical about the central axis of the main photodiode in the middle position.

[0013] Furthermore, the areas of the compensation photodiodes at different positions are different. From the middle position to both sides, the areas of the compensation photodiodes increase successively, but the widths of the compensation photodiodes are the same, only the heights are different, and they are axially symmetrical about the central axis of the compensation photodiode at the middle position.

[0014] Furthermore, each compensation photodiode is connected to a switch circuit, and the switch circuit corresponding to each compensation photodiode is controlled individually.

[0015] The photodiode detector of the present invention adopts an array design and is suitable for both incremental signals and absolute signals, with high flexibility. The photodiode group consists of a main photodiode and a plurality of compensation photodiodes. Different compensation photodiodes are selected by a switch to be connected to the main photodiode, which can adapt to light sources with different light intensity distributions. Moreover, the farther the photodiode is from the light source, the greater the area compensation is, so that the output signals of the photodiodes at various positions tend to be consistent, thereby improving the influence of light source fluctuations, having good stability and high responsiveness, and being suitable for rotary encoders. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention.

[0017] Figure 1 Schematic diagram of the normalized light intensity distribution of Model 1 light source in the Y and X directions.

[0018] Figure 2 Schematic diagram of the normalized light intensity distribution of model 2 light source in the Y and X directions.

[0019] Figure 3 Schematic diagram of the structure of a single photodiode.

[0020] Figure 4 Schematic diagram of the structure of the compensation photodiode on the upper side of the main photodiode.

[0021] Figure 5 Schematic diagram of the structure of the compensation photodiode on the lower side of the main photodiode.

[0022] Figure 6 Schematic diagram of the structure of compensation photodiodes on both sides of the main photodiode.

[0023] icon:

[0024] 10: Highly doped P-type semiconductor; 20: Metal 1; 30: Metal 2;

[0025] 40: Highly doped N-type semiconductor; 50: Compensated photodiode; 60: Metal wire;

[0026] 70: Main photodiode; 80: Switching circuit; 90: Metal pad DETAILED DESCRIPTION

[0027] To make the technical problems, technical solutions, and advantages to be solved by the present invention more clear, the following is a detailed description with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] like Figure 1 and Figure 2 As shown, two different types of light source chips from the same company have the same luminescent materials and luminescent wavelengths. However, due to the different package sizes, the two types of light sources have quite different light intensity distributions. If the compensation part of the photodiode array is designed for one light source in a traditional way, it cannot be applied to another light source chip. Therefore, when using different types of light sources, corresponding designs need to be made for different light sources, which increases the design difficulty and cost. The design method of the present invention can effectively solve this problem and achieve universality among multiple light source chips.

[0029] Figure 3 The diagram shows the structure of a single photodiode. Figure 3 The cathode of each photodiode shown is a highly doped N-type semiconductor 40, and each highly doped N-type semiconductor 40 is surrounded by an anode composed of a highly doped P-type semiconductor 10. The highly doped N-type semiconductor 40 and the highly doped P-type semiconductor 10 are connected to the external circuit through the metal electrode 30 and the metal electrode 20 respectively.

[0030] Figure 4 The schematic diagram of the structure of the compensation photodiode on the upper side of the main photodiode is as follows: Figure 4 The photodiode array shown is composed of a plurality of main photodiodes 70 with large areas and a plurality of compensation photodiodes 50 with small areas. Each main photodiode 70 and the compensation photodiodes 50 in the same column constitute a photodiode group. Several photodiode groups are arranged in parallel to form a photodiode array. The output signal of each compensation photodiode 50 in the same group is connected to the output of the main photodiode 70 in the group through a switching circuit 80 and connected to a metal pad 90.

[0031] Optionally, the main photodiodes and the compensation photodiodes are rectangular in shape, and the main photodiodes and the compensation photodiodes in the same group have the same width and different heights.

[0032] Optionally, the photodiode group consisting of the main photodiode and the compensation photodiode is arranged in parallel.

[0033] Optionally, the compensation photodiodes are located on the upper side of the main photodiodes, and the number of compensation photodiodes in each group is the same.

[0034] Optionally, the compensation photodiode may also be located at the lower side of the main photodiode, such as Figure 5 As shown, the number of compensation photodiodes in each group is the same.

[0035] Optionally, the compensation photodiode may also be located on the upper and lower sides of the main photodiode, such as Figure 6 As shown, the number of compensation photodiodes in each group is equal on the same side.

[0036] Optionally, the areas of the main photodiodes at different positions are different, and the areas of the main photodiodes increase successively from the middle position to both sides.

[0037] Optionally, the widths of the main photodiodes are the same, and only the heights are different. The heights of the main photodiodes increase from the middle position to both sides, and may only extend to the upper side, such as Figure 4 As shown; can only extend to the lower side, such as Figure 5 As shown; it can also extend to both sides, such as Figure 6 As shown; and the main photodiode array is axially symmetrical about the central axis of the main photodiode in the middle position.

[0038] Optionally, the areas of the compensation photodiodes at different positions are different, and the areas of the compensation photodiodes increase successively from the middle position to both sides, but the widths of the compensation photodiodes are the same, only the heights are different, and they are axially symmetrical about the central axis of the compensation photodiode at the middle position.

[0039] Optionally, each compensation photodiode is connected to a switch circuit, and the switch circuit corresponding to each compensation photodiode can be controlled individually.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0041] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0042] (1) The present invention combines multiple compensation photodiode parts for multiple light source chips, connects the output signals of each compensation part with the output signal of the main photodiode through a switching circuit, and selects different compensation parts to be turned on through the switching circuit to adapt to light source chips with different light intensity distributions. This breaks through the traditional single compensation based on a single light source chip and provides a new design method.

[0043] (2) The main photodiode and compensation photodiode designed in the present invention are designed to have a larger area the farther away from the light source, based on the characteristics of light intensity distribution. This achieves good consistency in the output signals of photodiodes at different positions, reduces the design complexity of the subsequent processing circuit, and improves signal reliability.

[0044] (3) The main photodiode and compensation photodiode designed in the present invention can adapt to light source chips with different light intensity distributions. Compared with the traditional design method in which one photodiode array chip is only suitable for one light source chip, the flexibility and universality of the photodiode array chip are improved, and the design complexity and design cost are reduced.

Claims

1. A photodiode array with area compensation, characterized in that: The photodiode array includes multiple main photodiodes and multiple compensation photodiodes with smaller areas than the main photodiodes. Each main photodiode and the compensation photodiodes in the same column constitute a photodiode group. Several photodiode groups are arranged in parallel to form a photodiode array. The output signal of each compensation photodiode in the same group is connected to the output of the main photodiode in the group through a switching circuit. The areas of the main photodiodes at different positions are different, and the areas of the main photodiodes increase from the middle position to the two sides.

2. The photodiode array according to claim 1, wherein: The main photodiode and the compensation photodiode are rectangular in shape, and the main photodiode and the compensation photodiode in the same group have the same width and different heights.

3. The photodiode array according to claim 1, wherein: A photodiode group consisting of a main photodiode and a compensation photodiode is arranged in parallel.

4. The photodiode array according to claim 1, wherein: The compensation photodiodes are all located on the same side of the main photodiode, and the number of compensation photodiodes in each group is the same.

5. The photodiode array according to claim 1, wherein: The compensation photodiodes are located on both sides of the main photodiode, and the number of compensation photodiodes included in each photodiode group on the same side is equal.

6. The main photodiode according to claim 1, wherein: The main photodiodes have the same width and only different heights. The heights of the main photodiodes increase from the middle position to both sides. Moreover, the main photodiode array is axisymmetric about the central axis of the main photodiode in the middle position.

7. The photodiode array according to claim 1, wherein: The areas of the compensation photodiodes at different positions are different. From the middle position to both sides, the areas of the compensation photodiodes increase successively. However, the widths of the compensation photodiodes are the same, and only the heights are different. Moreover, the compensation photodiodes are axially symmetrical about the central axis of the compensation photodiode at the middle position.

8. The photodiode array according to claim 1, wherein: Each compensation photodiode is connected to a switch circuit, and the switch circuit corresponding to each compensation photodiode is controlled separately.

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