Low-error gate opening sensor

Abstract

The invention relates to the technical field of opening degree sensors, and discloses a low-error gate opening degree sensor which comprises a rotary encoder, the rotary encoder is composed of a photoelectric coded disc and a detection element used for detecting the rotation angle of the photoelectric coded disc, and the photoelectric coded disc is composed of a rotating shaft, a first grating ruler and a second grating ruler. The first grating ruler and the second grating ruler are coaxially arranged and are the same in size, shading areas formed by strip-shaped shading films are arranged on the edges of the first grating ruler and the second grating ruler in a circumferential array mode, the detection element is composed of a control circuit base and a photoelectric sensor, and a light emitting diode capable of emitting light is arranged in the photoelectric sensor. Light emitted by the light emitting diode can penetrate through the first grating ruler and the second grating ruler to enter the photosensitive element, the light emitted by the light emitting diode can be absorbed by the shading film, the shading film on the second grating ruler is in a spiral shape, and a shading area formed by the shading film on the first grating ruler is sparse compared with a shading area formed by the shading film on the second grating ruler.

Description

Technical Field

[0001] The invention relates to the technical field of opening sensors, in particular to a low-error gate opening sensor. Background Art

[0002] The gate opening sensor determines the height of the water level or liquid level by measuring the opening of the gate. It can convert the position information of the gate into an electrical signal output, thereby realizing accurate monitoring and control of the gate opening. This sensor is widely used in water conservancy projects, power engineering, chemical engineering and other fields. The working principle of the gate opening sensor is mainly based on the synchronous movement of the rotary encoder and the coupler. When the gate moves vertically or rotationally, the coupler connected to the rotating shaft of the gate opening machine or directly connected to the gate will move synchronously. The coupler then drives the main shaft of the encoder to rotate. The encoder outputs the gate position coded electrical signal corresponding to the rotation position through the electrical socket. These electrical signals can be transmitted to the data acquisition system or PLC controller to realize automatic control and monitoring of the water level or liquid level.

[0003] The photoelectric rotary encoder is mainly composed of a light source, a code disk (grating) and a photosensitive element (optical reader). The light source usually uses an infrared light source to emit a light beam to the rotating part on the encoder. The code disk rotates with the measured axis and has a series of equally spaced transparent and opaque areas on it to form an optical code. The photosensitive element is used to detect the light beam reflected from the rotating part and convert it into an electrical signal. The shading part on the code disk is usually radial stripes for ease of processing. When such radial stripes are detected, if the only distance between two detections is the same as the stripe spacing, the accurate rotation angle cannot be recorded. At the same time, traditional photoelectric rotary encoders cannot detect the direction of rotation and are prone to deviations. Summary of the invention

[0004] (I) Technical problems to be solved: In view of the deficiencies in the prior art, the present invention provides a low-error gate opening sensor, which has the advantage of low-error detection and solves the problem of deviation in the detection of the opening sensor.

[0005] (II) Technical solution: To achieve the purpose of the above-mentioned low-error detection, the present invention provides the following technical solution: a low-error gate opening sensor, comprising a rotary encoder, the rotary encoder is composed of a photoelectric code disk and a detection element for detecting the rotation angle of the photoelectric code disk, the photoelectric code disk is connected to the rotating shaft of the gate hoist, the photoelectric code disk is composed of a rotating shaft, a first grating ruler and a second grating ruler, the first grating ruler and the second grating ruler are coaxially arranged and have the same size, the first grating ruler and the second grating ruler are transparent disc-shaped, and the circumferential array at the edge of the first grating ruler and the second grating ruler has a strip-shaped shading film formed The light-shielding area, the detection element is composed of a control circuit base and a photoelectric sensor, the photoelectric sensor is provided with a light-emitting diode that can emit light, the light emitted by the light-emitting diode can pass through the first grating scale and the second grating scale into the photosensitive element, and the light emitted by the light-emitting diode will be absorbed by the light-shielding film, the light-shielding film on the second grating scale is spiral, and the shielding area formed by the light-shielding film on the first grating scale is sparse compared to the shielding area on the second grating scale, and the light spot that passes through the light-transmitting area of ​​the second grating scale and irradiates the photosensitive element will produce displacement on the photosensitive element as the photoelectric code disk rotates.

[0006] Preferably, the shading film provided on the first grating scale is radial, and the light emitted by the light emitting diode passes through the light-transmitting areas on the second grating scale and the first grating scale, and the light spots formed on the photosensitive element are in the shape of arc strips.

[0007] Preferably, the shading film arranged on the first grating scale is spiral-shaped, and its inclination angle is 180° different from that of the shading film on the second grating scale. The light emitted by the light-emitting diode passes through the light-transmitting areas on the second grating scale and the first grating scale, and the light spot formed on the photosensitive element is diamond-shaped.

[0008] Preferably, the photoelectric sensor is arranged on a control circuit base, and the control circuit base and the photoelectric code disk are arranged on the same plane of the rotary encoder and are detachably connected.

[0009] Preferably, the edge of the upper surface of the first grating scale is tilted downward, and the tilt angle is greater than 2° and less than 5°.

[0010] Preferably, the first grating scale and the second grating scale are made of glass, and the shading film is a metal wire embedded in the first grating scale and the second grating scale.

[0011] Preferably, a light shield is provided outside the light emitting diode and the photosensitive element.

[0012] Preferably, gaps are arranged at intervals on the light shield.

[0013] (III) Beneficial effects: Compared with the prior art, the present invention provides a low-error gate opening sensor having the following beneficial effects: 1. The low-error gate opening sensor, through the coaxial and equal-sized design of the first grating scale and the second grating scale, can produce complementary shading effects when rotating. This design not only improves the measurement accuracy, but also enables the sensor to capture more subtle changes in rotation angle, thereby improving the resolution. The spiral shading film design on the second grating scale makes the light spot received by the photosensitive element produce continuous displacement changes during the rotation process. This continuous displacement change provides the sensor with richer measurement data, which helps to more accurately calculate the rotation angle and gate opening height. Traditional rotary encoders may cause misjudgment at a specific rotation angle due to the consistency of the shading film gap with the rotation angle. The dual grating scale structure of the present design can achieve misjudgment even in this case. In this case, different shading effects can be produced by the spiral shading film of the second grating ruler, thereby avoiding misjudgment. The redundant design of the first grating ruler and the second grating ruler enables the sensor to maintain high measurement accuracy in harsh environments (such as dust, water drops, etc.). Even if one of the grating rulers is disturbed, the other grating ruler can provide reliable measurement data, thereby improving the reliability of the sensor. Due to the spiral design of the second grating ruler, when the photoelectric code disk rotates, the light spot received on the photosensitive element will be displaced, and the direction of this displacement can indicate the direction of rotation. This design not only improves the measurement accuracy, but also provides feedback on the direction of rotation for the control system. By monitoring the displacement speed and frequency of the light spot on the photosensitive element, the rotation speed can be calculated. This design enables the sensor to measure the rotation angle, direction and speed at the same time, providing more comprehensive information for the control system.

[0014] 2. For the low-error gate opening sensor, when the shading film on the first grating scale is radial, its design and manufacturing process is relatively simple, because the radial pattern is easier to realize through machining or photolithography technology. The radial shading film can reduce the measurement error caused by uneven rotation or vibration. Because the light passes through a fixed and evenly distributed light-transmitting area, even if the rotation speed changes, the position change of the light spot on the photosensitive element is relatively stable. Combined with the second grating scale with a spiral design, the first grating scale with a radial shading film can provide additional measurement information. When the second grating scale cannot be accurately measured for some reason (such as contamination or damage), the first grating scale can still provide reliable measurement data. Due to the regularity of the radial shading film, it is easier to determine key parameters such as zero point and full scale during sensor calibration.

[0015] 3. For this low-error gate opening sensor, when the shading films on the two grating scales are spiral-shaped and the inclination angles differ by 180°, they can offset each other's measurement deviation caused by the rotation angle error. This design can further improve the measurement accuracy and stability. Since the shading films of the two grating scales are designed differently, their sensitivities to external interference (such as dust, water droplets, etc.) are also different. Therefore, even if one of the grating scales is disturbed, the other grating scale can provide reliable measurement data, thereby enhancing the sensor's anti-interference ability.

[0016] 4. The low-error gate opening sensor, the first grating scale and the second grating scale are made of glass. This material has high light transmittance and good dimensional stability, which helps to ensure the clarity and accuracy of the grating signal. The glass material also has high hardness and corrosion resistance, and can resist the erosion of dust, dirt and other pollutants in the environment, thereby extending the service life of the grating scale. The embedded metal wire shading film as part of the grating can accurately control the transmission and interruption of light, forming clear moiré fringes, improving the resolution and accuracy of the measurement. The stability and durability of the metal wire also ensure long-term The reliability of measurement, the light shield set outside the light-emitting diode and the photosensitive element, especially the gap design set at intervals on it, effectively utilizes the dynamic characteristics of the airflow. When the airflow enters the inside of the light shield through these narrow gaps, the airflow will diverge and form vortices. This irregular movement helps to blow away the water vapor that may accumulate in the light shield. By preventing the water vapor from condensing into water droplets, this design avoids the interference of water droplets on the light signal and ensures the stable operation of the grating scale measurement system in high humidity or changing humidity environments. This is crucial for many industrial applications, especially those requiring high-precision measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The structure of the present invention is shown in FIG. Figure 1 .

[0018] Figure 2 The structure of the present invention is shown in FIG. Figure 2 .

[0019] Figure 3 Schematic diagram of the detection element of the present invention Figure 1 .

[0020] Figure 4 Schematic diagram of the detection element of the present invention Figure 2 .

[0021] Figure 5 FIG. 1 is a schematic diagram of a light-shielding film according to an embodiment of the present invention.

[0022] Figure 6 Schematic diagram of a light-shielding film according to the second embodiment of the present invention.

[0023] In the figure: 1, rotary encoder; 2, photoelectric code disk; 3, detection element; 21, first grating scale; 22, second grating scale; 31, control circuit base; 32, photoelectric sensor; 211, shading film; 321, light-emitting diode; 322, photosensitive element; 323, shading cover. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1: Please refer to Figure 1-Figure 3 and Figure 5 The low error gate opening sensor comprises a rotary encoder 1, wherein the rotary encoder 1 is composed of a photoelectric code disk 2 and a detection element 3 for detecting the rotation angle of the photoelectric code disk 2, wherein the photoelectric code disk 2 is connected to the rotating shaft of the gate hoist, wherein the photoelectric code disk 2 is composed of a rotating shaft, a first grating ruler 21 and a second grating ruler 22, wherein the first grating ruler 21 and the second grating ruler 22 are coaxially arranged and have the same size, wherein the first grating ruler 21 and the second grating ruler 22 are transparent disc-shaped, and the circumferential array at the edge of the first grating ruler 21 and the second grating ruler 22 has a shading area formed by a strip shading film 211, wherein the detection element 3 is composed of a control circuit base 31 and a photoelectric sensor 32, the photoelectric sensor 32 is provided with a light-emitting diode 321 capable of emitting light, the light emitted by the light-emitting diode 321 can pass through the first grating scale 21 and the second grating scale 22 into the photosensitive element 322, and the light emitted by the light-emitting diode 321 will be absorbed by the shading film 211, the shading film 211 on the second grating scale 22 is spiral, and the shading area formed by the shading film 211 on the first grating scale 21 is sparse compared with the shading area on the second grating scale 22, and the light spot that passes through the light-transmitting area of ​​the second grating scale 22 and irradiates on the photosensitive element 322 will generate displacement on the photosensitive element 322 as the photoelectric code disk 2 rotates.

[0026] When the gate moves vertically, the photoelectric code disk 2 is connected to the rotating shaft of the gate opening and closing machine to make it rotate synchronously. When the first grating scale 21 and the second grating scale 22 on the photoelectric code disk 2 rotate, the shading film 211 on the upper surface rotates accordingly, so that the light emitted by the light-emitting diode 321 in the photoelectric sensor 32 is intermittently blocked by the shading film 211. The light emitted by the light-emitting diode 321 is recorded by the photosensitive element 322. The overall rotation of the photoelectric code disk 2 is calculated by the output signal change, and the gate opening height is calculated. The shading film 211 on the grating scale of the traditional rotary encoder 1 is a radially uniform circular array. When the photosensitive element 322 collects twice, there may be a situation where the rotation angle is consistent with the gap angle of the shading film 211, causing the photosensitive element 322 to mistakenly believe that the rotation angle is zero. At the same time, it is impossible to judge whether the rotation angle is positive or negative. In this application, a double grating scale structure of the first grating scale 21 and the second grating scale 22 is used, and the first grating scale 21 The light shielding film 211 on the first grating scale 21 is the same size as the second grating scale 22 and is coaxially arranged. The shielding area formed by the light shielding film 211 on the first grating scale 21 is sparser than that on the second grating scale 22, and the light shielding film 211 on the second grating scale 22 is spiral, so that even if the rotation angle of the photoelectric code disk 2 is the same as the interval angle of the light shielding film 211 on the first grating scale 21, the shielding area on the second grating scale 22 between adjacent light shielding films 211 on the first grating scale 21 will be different, and the light generated by the light emitting diode 321 passes through the second grating scale The light spot generated by the light-transmitting area on the shading film 211 on the grating scale 22 on the photosensitive element 322 will be displaced on the photosensitive element 322 as the rotation proceeds, so the change in the rotation angle can be judged more accurately. At the same time, due to the setting of two grating scales, and the shading area of ​​the second grating scale 22 is denser than the shading area of ​​the first grating scale 21, the influence of the first grating scale 21 on the light is reduced. Even if there is water droplet refraction on the first grating scale 21, it can be corrected by the second grating scale 22.

[0027] See also Figure 5 , the dotted line in the figure represents the position of the shading film 211 of the second grating scale 22, the shading film 211 set on the first grating scale 21 is radial, the light emitted by the light-emitting diode 321 passes through the light-transmitting areas on the second grating scale 22 and the first grating scale 21, and the light spot formed on the photosensitive element 322 is an arc strip.

[0028] The photoelectric sensor 32 is arranged on the control circuit base 31 . The control circuit base 31 and the photoelectric encoder disk 2 are arranged on the same plane of the rotary encoder 1 and are detachably connected.

[0029] The edge of the upper surface of the first grating ruler 21 is tilted downward, and the tilt angle is greater than 2° and less than 5°, so that when there are water droplets on the upper surface of the first grating ruler 21, they can be quickly thrown out from the upper surface as it rotates.

[0030] The first grating scale 21 and the second grating scale 22 are made of glass, and the shading film 211 is a metal wire embedded in the first grating scale 21 and the second grating scale 22 .

[0031] See also Figure 4 A light shield 323 is provided outside the light emitting diode 321 and the photosensitive element 322. The light shield 323 is provided with gaps at intervals. When the airflow penetrates into the light shield 323 from the gaps, it enters the larger space from the narrow gap, which will cause the airflow to diverge and form an irregular vortex, blowing away the water vapor in the light shield 323 to prevent condensation into water droplets and interfere with detection.

[0032] Example 2: Please refer to Figure 1-Figure 3 and Figure 6 The low error gate opening sensor comprises a rotary encoder 1, wherein the rotary encoder 1 is composed of a photoelectric code disk 2 and a detection element 3 for detecting the rotation angle of the photoelectric code disk 2, wherein the photoelectric code disk 2 is connected to the rotating shaft of the gate hoist, wherein the photoelectric code disk 2 is composed of a rotating shaft, a first grating ruler 21 and a second grating ruler 22, wherein the first grating ruler 21 and the second grating ruler 22 are coaxially arranged and have the same size, wherein the first grating ruler 21 and the second grating ruler 22 are transparent disc-shaped, and the circumferential array at the edge of the first grating ruler 21 and the second grating ruler 22 has a shading area formed by a strip shading film 211, wherein the detection element 3 is composed of a control circuit base 31 and a photoelectric sensor 3 2, the photoelectric sensor 32 is provided with a light-emitting diode 321 capable of emitting light, the light emitted by the light-emitting diode 321 can pass through the first grating scale 21 and the second grating scale 22 into the photosensitive element 322, and the light emitted by the light-emitting diode 321 will be absorbed by the shading film 211, the shading film 211 on the second grating scale 22 is spiral, and the shading area formed by the shading film 211 on the first grating scale 21 is sparser than the shading area on the second grating scale 22, and the light spot that passes through the light-transmitting area of ​​the second grating scale 22 and irradiates the photosensitive element 322 will generate displacement on the photosensitive element 322 as the photoelectric code disk 2 rotates.

[0033] When the gate moves vertically, the photoelectric code disk 2 is connected to the rotating shaft of the gate opening and closing machine to make it rotate synchronously. When the first grating scale 21 and the second grating scale 22 on the photoelectric code disk 2 rotate, the shading film 211 on the upper surface rotates accordingly, so that the light emitted by the light-emitting diode 321 in the photoelectric sensor 32 is intermittently blocked by the shading film 211. The light emitted by the light-emitting diode 321 is recorded by the photosensitive element 322. The overall rotation of the photoelectric code disk 2 is calculated by the output signal change, and the gate opening height is calculated. The shading film 211 on the grating scale of the traditional rotary encoder 1 is a radially uniform circular array. When the photosensitive element 322 collects twice, there may be a situation where the rotation angle is consistent with the gap angle of the shading film 211, causing the photosensitive element 322 to mistakenly believe that the rotation angle is zero. At the same time, it is impossible to judge whether the rotation angle is positive or negative. In this application, a double grating scale structure of the first grating scale 21 and the second grating scale 22 is used, and the first grating scale 21 The light shielding film 211 on the first grating scale 21 is the same size as the second grating scale 22 and is coaxially arranged. The shielding area formed by the light shielding film 211 on the first grating scale 21 is sparser than that on the second grating scale 22, and the light shielding film 211 on the second grating scale 22 is spiral, so that even if the rotation angle of the photoelectric code disk 2 is the same as the interval angle of the light shielding film 211 on the first grating scale 21, the shielding area on the second grating scale 22 between adjacent light shielding films 211 on the first grating scale 21 will be different, and the light generated by the light emitting diode 321 passes through the second grating scale The light spot generated by the light-transmitting area on the shading film 211 on the grating scale 22 on the photosensitive element 322 will be displaced on the photosensitive element 322 as the rotation proceeds, so the change in the rotation angle can be judged more accurately. At the same time, due to the setting of two grating scales, and the shading area of ​​the second grating scale 22 is denser than the shading area of ​​the first grating scale 21, the influence of the first grating scale 21 on the light is reduced. Even if there is water droplet refraction on the first grating scale 21, it can be corrected by the second grating scale 22.

[0034] See also Figure 6 , the dotted line in the figure represents the position of the shading film 211 of the second grating scale 22, the shading film 211 arranged on the first grating scale 21 is spiral, and the inclination angle is 180° different from the shading film 211 on the second grating scale 22, the light emitted by the light-emitting diode 321 passes through the light-transmitting areas on the second grating scale 22 and the first grating scale 21, and the light spot formed on the photosensitive element 322 is diamond-shaped.

[0035] The photoelectric sensor 32 is arranged on the control circuit base 31 . The control circuit base 31 and the photoelectric encoder disk 2 are arranged on the same plane of the rotary encoder 1 and are detachably connected.

[0036] The edge of the upper surface of the first grating ruler 21 is tilted downward, and the tilt angle is greater than 2° and less than 5°, so that when there are water droplets on the upper surface of the first grating ruler 21, they can be quickly thrown out from the upper surface as it rotates.

[0037] The first grating scale 21 and the second grating scale 22 are made of glass, and the shading film 211 is a metal wire embedded in the first grating scale 21 and the second grating scale 22 .

[0038] See also Figure 4 A light shield 323 is provided outside the light emitting diode 321 and the photosensitive element 322. The light shield 323 is provided with gaps at intervals. When the airflow penetrates into the light shield 323 from the gaps, it enters the larger space from the narrow gap, which will cause the airflow to diverge and form an irregular vortex, blowing away the water vapor in the light shield 323 to prevent condensation into water droplets and interfere with detection.

[0039] Working principle: When the gate moves vertically, the photoelectric code disk 2 is connected to the rotating shaft of the gate opening and closing machine to make it rotate synchronously. When the first grating scale 21 and the second grating scale 22 on the photoelectric code disk 2 rotate, the shading film 211 on the upper surface rotates accordingly, so that the light emitted by the light-emitting diode 321 in the photoelectric sensor 32 is intermittently blocked by the shading film 211. The light emitted by the light-emitting diode 321 is recorded by the photosensitive element 322. The overall rotation of the photoelectric code disk 2 is calculated by the output signal change, and the gate opening height is calculated. The shading film 211 on the grating scale of the traditional rotary encoder 1 is a radially uniform circular array. When the photosensitive element 322 collects twice, there may be a situation where the rotation angle is consistent with the gap angle of the shading film 211, causing the photosensitive element 322 to mistakenly believe that the rotation angle is zero. At the same time, it is impossible to judge whether the rotation angle is positive or negative. In this application, a double grating scale structure of the first grating scale 21 and the second grating scale 22 is used, and the first grating scale 21 The light shielding film 211 on the first grating scale 21 is the same size as the second grating scale 22 and is coaxially arranged. The shielding area formed by the light shielding film 211 on the first grating scale 21 is sparser than that on the second grating scale 22, and the light shielding film 211 on the second grating scale 22 is spiral, so that even if the rotation angle of the photoelectric code disk 2 is the same as the interval angle of the light shielding film 211 on the first grating scale 21, the shielding area on the second grating scale 22 between adjacent light shielding films 211 on the first grating scale 21 will be different, and the light generated by the light emitting diode 321 passes through the second grating scale The light spot generated by the light-transmitting area on the shading film 211 on the grating scale 22 on the photosensitive element 322 will be displaced on the photosensitive element 322 as the rotation proceeds, so the change in the rotation angle can be judged more accurately. At the same time, due to the setting of two grating scales, and the shading area of ​​the second grating scale 22 is denser than the shading area of ​​the first grating scale 21, the influence of the first grating scale 21 on the light is reduced. Even if there is water droplet refraction on the first grating scale 21, it can be corrected by the second grating scale 22.

[0040] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-error gate opening sensor, comprising a rotary encoder (1), wherein the rotary encoder (1) is composed of a photoelectric encoder (2) and a detection element (3) for detecting the rotation angle of the photoelectric encoder (2), wherein the photoelectric encoder (2) is connected to a rotating shaft of a gate hoist in the gate, and wherein: The photoelectric code disk (2) is composed of a rotating shaft, a first grating scale (21) and a second grating scale (22); the first grating scale (21) and the second grating scale (22) are coaxially arranged and have the same size; the first grating scale (21) and the second grating scale (22) are transparent disc-shaped; and the circumferential array at the edge of the first grating scale (21) and the second grating scale (22) has a light shielding area formed by a strip-shaped light shielding film (211); the detection element (3) can emit light and pass through the first grating scale (21) and the second grating scale (22) to form a light spot on the detection element (3) located below the light spot code disk (2); and the light emitted by the detection element (3) is absorbed by the light shielding film (211); the light shielding film (211) on the second grating scale (22) is spiral-shaped; and the light spot passing through the light-transmitting area of ​​the second grating scale (22) will generate displacement on the detection element (3) as the photoelectric code disk (2) rotates.

2. The low error gate opening sensor according to claim 1, characterized in that: The detection element (3) is composed of a control circuit base (31) and a photoelectric sensor (32); a light emitting diode (321) capable of emitting light is provided in the photoelectric sensor (32); the photoelectric sensor (32) is arranged below the light spot code disk (2); and a photosensitive element (322) for detecting movement of the light spot is provided on the photoelectric sensor (32).

3. The low error gate opening sensor according to claim 2, characterized in that: The shielding area formed by the shading film (211) on the first grating ruler (21) is more sparse than the shielding area on the second grating ruler (22).

4. The low error gate opening sensor according to claim 3, characterized in that: The shading film (211) provided on the first grating ruler (21) is radially shaped, and the light emitted by the light emitting diode (321) passes through the light-transmitting areas on the second grating ruler (22) and the first grating ruler (21), and the light spots formed on the photosensitive element (322) are in the shape of arc strips.

5. The low error gate opening sensor according to claim 3, characterized in that: The shading film (211) provided on the first grating scale (21) is spiral-shaped and has an inclination angle that is 180° different from that of the shading film (211) on the second grating scale (22). Light emitted by the light-emitting diode (321) passes through the light-transmitting areas on the second grating scale (22) and the first grating scale (21), and a light spot formed on the photosensitive element (322) is in a rhombus shape.

6. The low error gate opening sensor according to claim 5, characterized in that: The photoelectric sensor (32) is arranged on a control circuit base (31); the control circuit base (31) and the photoelectric code disk (2) are arranged on the same plane of the rotary encoder (1) and are detachably connected.

7. The low error gate opening sensor according to claim 1, characterized in that: The edge of the upper surface of the first grating scale (21) is inclined downward, and the inclination angle is greater than 2° and less than 5°.

8. The low error gate opening sensor according to any one of claims 4-5, characterized in that: The first grating scale (21) and the second grating scale (22) are made of glass, and the light shielding film (211) is a metal wire embedded in the first grating scale (21) and the second grating scale (22).

9. The low error gate opening sensor according to claim 2, characterized in that: A light shield (323) is provided outside the light emitting diode (321) and the photosensitive element (322).

10. The low error gate opening sensor according to claim 9, characterized in that: Gaps are arranged at intervals on the light shield (323).

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