CN118729954A - A detector for detecting linear displacement position - Google Patents

Abstract

The invention discloses a detector for detecting a linear displacement position, which relates to the technical field of linear displacement position detection equipment, the detector for detecting the linear displacement position is directly connected with the driving module through a light shielding sheet with a unique shape, and the driving module is simultaneously and directly connected with the movable element. The light shielding sheet is used for partially shielding two rectangular light sensors which are precisely symmetrical and have the same area, so that the whole photosensitive area of the two rectangular light sensors cannot completely receive light from a single emitting tube light source. When the uniquely shaped gobo moves linearly with the linearly displaceable movable element, it exposes more of the photosensitive area of one of the side photosensors and relatively less of the photosensitive area of the other side photosensor. In order to obtain better linearity, a light homogenizing sheet or a Fresnel lens can be added between the light source of the emitting tube and the light shielding sheet, so that a more uniform light field is obtained, and the detection result is more accurate.

Description

A detector for detecting linear displacement position

Technical Field

The present invention relates to the technical field of linear displacement position detection equipment, and in particular to a detector for detecting linear displacement position.

Background Art

The present invention is widely used for position detection of short-distance linear motion elements, usually in optical dynamic focusing systems, high-precision mechanical micro-motion platforms, etc., where the detector is required to have high resolution, high dynamic response, and high reliability.

At present, the commonly used position detectors of linear motion elements are mainly magnetic scales and grating scales. The magnetic scale is a length measurement system that uses the principle of magnetic field and Hall element for measurement. However, it has the following disadvantages:

1. High cost: Due to the use of high-precision Hall elements and complex digital circuit processing, the cost is relatively high.

2. Accuracy is easily affected by temperature changes: Since the sensitivity of the Hall element is related to temperature, temperature compensation is required in an environment with large temperature changes.

The grating ruler is a length measurement system that uses optical principles for measurement. It has the following disadvantages:

1. High price: Compared with magnetic scale, optical scale is more expensive.

2. Susceptible to contamination: The surface of the grating ruler is very fine and easily affected by contamination and scratches, resulting in reduced measurement accuracy.

3. High installation requirements: The installation requirements of the grating ruler are high, requiring a stable position, poor vibration resistance and short life.

Therefore, the object of the present invention is to provide an optical detector which can adapt to an environment with a large temperature difference and can accurately detect the position of a linear motion element.

It is therefore another object of the present invention to provide a low-cost optical detector of the position of a linear motion element which is small in size, has a small number of components, and is easy to install.

Summary of the invention

1. Technical issues to be solved

In view of the deficiencies in the prior art, the present invention provides a detector for detecting a linear displacement position to solve the following technical problems.

(II) Technical solution

To achieve the above objectives, the present invention is implemented through the following technical solutions:

A detector for detecting linear displacement position comprises a fixed base on which a detector module for monitoring, a linearly movable element capable of linear movement and a driving module for driving components in the detector module and the linearly movable element are arranged.

The moving end of the driving module is fixedly connected to the linearly movable element and the light shielding sheet in the detector module, and the driving module drives the linearly movable element and the light shielding sheet to move linearly at the same time.

Among them, the detector module includes a single transmitting tube light source that generates a uniform wide-angle light field and a light sensor that receives the light source. The single transmitting tube light source and the light sensor are in the same vertical plane. The distance k between the single transmitting tube light source and the light sensor is determined by the divergence angle θ of the light source and the width n of the light sensor. The specific calculation formula is: k=cotangentθ×(1/2×n), and the shading plate is located between the single transmitting tube light source and the light sensor.

The light sensor includes two rectangular light sensors that are precisely symmetrical and have exactly the same area, and the light shielding sheet cannot completely block a single rectangular light sensor.

Preferably: the linearly movable element is slidably connected to the fixed base via a guide rail assembly, and a limiting column is fixed on the top of the fixed base at the moving end of the driving module, and the limiting column is used to limit the moving distance of the moving end of the driving module.

Preferably: the detector module includes an outer shell cover, which is fixed on a fixed base, a transmitting tube bracket is arranged at the bottom of the inner wall of the outer shell cover, a light sensor is fixed between the transmitting tube bracket and the outer shell cover, a single transmitting tube light source is fixed at the center position of the top of the transmitting tube bracket, a rectangular hole is opened on one side close to the outer shell cover and the linearly movable element, a shading sheet passes through the rectangular hole and is arranged inside the outer shell cover and is located above the light sensor, a window sheet is arranged on the top of the light sensor, the window sheet is located between the shading sheet and the light sensor, and there is no other obstruction in the space between the shading sheet and the light sensor except the window sheet.

Preferably, the shading sheet is made of a material that is high in hardness, light in weight, and opaque.

Preferably, a light homogenizer is provided at the bottom of the single emitting tube light source, and the light homogenizer is fixed on the outer shell cover.

(III) Beneficial effects

1. The present invention is directly connected to the driving module through a shading plate of a unique shape, and the driving module is also directly connected to the movable element. The shading plate is used to partially block two precisely symmetrical and identical rectangular light sensors, so that the entire photosensitive area of the two rectangular light sensors cannot fully receive light from a single transmitting tube light source. The transmitting tube light source must be able to produce a uniform wide-angle light field to evenly illuminate the two light sensors. When the shading plate of a unique shape moves linearly with the linearly displaceable movable element, it will expose more photosensitive areas of the light sensor on one side, while exposing relatively less photosensitive areas of the light sensor on the other side. In order to obtain better linearity, you can choose to add a light-homogenizing plate or a Fresnel lens between the transmitting tube light source and the shading plate to obtain a more uniform light field, making the detection result more accurate.

2. In the present invention, when the light intensity is constant, the output of the light sensor is proportional to the area of the light sensor exposed to the light. The currents of the two light sensors are connected to the positive and negative electrodes of the differential amplifier to produce the final output. The final output from the light sensor represents the linear displacement of the movable element.

3. The overall setup has a small number of components, is easy to install and low cost, and can bring good detection results.

BRIEF DESCRIPTION OF THE DRAWINGS

The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

Fig. 1 is a schematic diagram of the three-dimensional structure of the invention;

Fig. 2 is a schematic diagram of the cross-sectional structure of the invention;

FIG3 is a schematic diagram of the three-dimensional structure of the invented optical sensor;

FIG4 is a schematic diagram of the structure of the light shielding sheet of the invention;

FIG5 is a cross-sectional front and side view of a sensor assembly using a specially shaped blocking member according to the present invention, and also includes an illustration of the distance between the light shielding sheet and the light sensor;

Figure 6 is a design diagram for the height of a single transmitting tube light source and a transmitting tube bracket. Legend: Module 1, detector module; Module 2, drive module; Module 3, movable element; 4, light shielding sheet; 5, guide rail assembly; 6, limit column; 7, fixed base; 8, mounting hole; 9, window sheet; 10, light sensor; 11, outer cover; 12, side baffle; 13, transmitting tube bracket; 14, transmitting tube light source; 15, light homogenizer.

DETAILED DESCRIPTION

1-6 , an embodiment of the present application provides a detector for detecting a linear displacement position, including a fixed base 7, on which is disposed a detector module 1 for monitoring, a linearly movable element module 3 capable of linear movement, and a driving module 2 for driving components in the detector module 1 and the linearly movable element module 3 to move.

The moving end of the driving module 2 is fixedly connected to the linearly movable element module 3 and the light shielding sheet 4 in the detector module 1, and the driving module 2 drives the linearly movable element module 3 and the light shielding sheet 4 to move linearly at the same time.

In some implementation cases, in order to ensure a faster speed and require a greater torque, two driving modules 2 are used to move the linearly movable element module 3 in a push-pull manner.

The shading sheet 4 is made of a material with high hardness, light weight, and opaqueness to avoid vibration or shaking caused by rapid acceleration/deceleration of linear motion.

Among them, the detector module 1 includes a single emitting tube light source 14 that generates a uniform wide-angle light field and a light sensor 10 that receives the light source. The single emitting tube light source 14 and the light sensor 10 are in the same vertical plane. The distance k between the single emitting tube light source 14 and the light sensor 10 is determined by the divergence angle θ of the light source and the width n of the light sensor. The specific calculation formula is: k=cotangentθ×(1/2×n). The shading plate 4 is located between the single emitting tube light source 14 and the light sensor 10.

This ensures that the light field emitted by the single emitting tube light source 14 can completely and evenly cover the entire photosensitive area of the two light sensors 10. At the same time, the window sheet 9 covering the light sensors 10 ensures that the exposed areas of the two light sensors 10 are precisely symmetrical and completely equal, and the k value can also fully ensure that the light field emitted by the single emitting tube light source 14 can completely cover the photosensitive areas of the two light sensors 10 exposed under the window sheet 9. The total exposed length n of the window of the window sheet 9 can be completely covered by the uniform light field emitted by the single emitting tube light source, thereby ensuring the validity and accuracy of the output results, and also ensuring that the installation size of the displacement detector is as small as possible.

The single-emission tube light source 14 is a type that can produce a uniform wide-angle light field. It is necessary to uniformly illuminate all light sensors 10 at the same time. The distance between the single-emission tube light source 14 and the light sensor 10 is crucial and is calculated based on the divergence angle of the single LED light source 14 and the square sensor photosensitive area. The calculated distance between the light sensor 10 and the single-emission tube light source 14 can ensure the light sensor illumination area and the received radiation intensity, thereby ensuring high-quality signal generation. Equally important is the unique shape of the blocking member 4, which must be located very close to the light sensor 10, that is, the A value in Figure 5 is about 0.05 to 0.10 inches. In this way, the light can be projected onto the surface of the light sensor 10 as closely as possible to the contour of the light shielding sheet 4.

The optical sensor 10 includes two rectangular optical sensors that are precisely symmetrical and have exactly the same area, and the light shielding sheet 4 cannot completely shield a single rectangular optical sensor.

The linearly movable element module 3 is slidably connected to the fixed base 7 through the guide rail assembly 5. The top of the fixed base 7 is located at the moving end of the driving module 2 and a limiting column 6 is fixed thereon. The limiting column 6 is used to limit the moving distance of the moving end of the driving module 2.

The detector module 1 includes an outer shell cover 11, which is fixed on a fixed base 7. A transmitting tube bracket 13 is provided at the bottom of the inner wall of the outer shell cover 11. A light sensor 10 is fixed between the transmitting tube bracket 13 and the outer shell cover 11. A single transmitting tube light source 14 is fixed at the top center of the transmitting tube bracket 13. A rectangular hole is provided on one side of the outer shell cover 11 and the linearly movable element module 3. A side baffle 12 is fixed on one side of the outer shell cover 11. With the installation of the side baffle 12, there is a gap as small as possible between the light shielding sheet 4 and other mounting parts in the linear displacement detector module, and The height differences mutually block the optical path of the outer shell cover 11, ensuring to the greatest extent that the uniform light field inside the outer shell cover 11 is not disturbed by external stray light, and also ensuring that the light field inside the outer shell cover 11 will not leak outward and cause other interference conditions, thereby ensuring the output accuracy of the light sensor 10. The shading sheet 4 is arranged inside the outer shell cover 11 through the rectangular hole and is located above the light sensor 10. A window sheet 9 is arranged on the top of the light sensor 10. The window sheet 9 is located between the shading sheet 4 and the light sensor 10, and there is no other obstruction in the space between the shading sheet 4 and the light sensor 10 except the window sheet 9.

The single emitting tube light source 14, the light sensor 10 and the unique shape blocking member 4 are specially designed in the outer shell 11 and the side baffle 12 as shown in FIG2. The unique shape of the blocking member design greatly reduces the possibility of external light interference and ensures the reliability and stability of the signal output.

A light homogenizer 15 is disposed at the bottom of the single emitting tube light source 14 , and the light homogenizer 15 is fixed on the outer shell 11 .

In the present invention, the wide-angle light source characteristics are utilized to enable the use of a single LED light source. If the consistency of the light source can be guaranteed and the square is uniform, a configuration of multiple emitting tube narrow-angle light sources can be adopted. By reasonably calculating the distance between the single emitting tube light source 14 and the light sensor 10, the single emitting tube light source 14 can simultaneously and uniformly illuminate all light sensor 10 receiving surfaces, which is crucial to achieving high-precision results. As the uniquely shaped blocking member 4 moves in a straight line, it covers and exposes new incremental light sensor areas. In order for the output of the device to be linear, the new incremental area must produce the same signal change as the previous incremental area. This requires that the light intensity/density is uniform on the light sensor 10, which leads to the single emitting tube light source 14 used in the present invention.

In this application example: PSI dynamic axis module, the standard/optimal movable stroke of the movable element is ±3.5mm. In this stroke range, good linearity can be guaranteed, that is, the optimal stroke length is 7mm. The limit movement position of the movable element is less than ±4mm, that is, the limit stroke is less than 8mm. Each optical sensor has a maximum length of 10mm square. Since there is a certain deviation in the maximum length of the sensor, two windows slightly smaller than 10mm need to be precisely machined to ensure that the light receiving surfaces of the two sensors are consistent. In this case, a window piece with two windows with a length of 9.5mm was processed.

The width of the seam position of the window separating two precisely symmetrical and equal light sensors is 0.5mm. When it is at the extreme position of +4mm or -4mm, the position to which the light shield moves is shown in the figure, which has completely exposed the entire area of the exposed part of the lower half of the light sensor. At this time, the measurement result is invalid. Therefore, when the movable element moves within the movable stroke range, for example, when the movable element moves linearly to the +3.5mm position and the -3.5mm position, the lower edge of the light shield is 9mm away from the lower edge of the lower half of the window, that is, it blocks 0.5mm of the lower half of the light sensor, and the upper edge of the light shield is 2mm away from the upper edge of the upper half of the window (the total length of the exposed length of the upper half of the sensor is 9.5mm-the total length of the light shield is 8.5mm-the width of the seam of the window is 0.5mm-the length of the lower half of the light sensor covered by the light shield is 0.5mm.

Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims (8)

1. A detector for detecting a linear displacement position, comprising a fixed base (7), characterized in that a detector module (1) for monitoring, a linearly movable element module (3) capable of linear movement, and a driving module (2) for driving components in the detector module (1) and the linearly movable element module (3) are arranged on the fixed base (7); The moving end of the driving module (module 2) is fixedly connected to the linearly movable element (module 3) and the light shielding sheet (4) in the detector module (module 1), and the driving module (module 2) drives the linearly movable element (module 3) and the light shielding sheet (4) to move linearly at the same time; The detector module (module 1) comprises a single transmitting tube light source (14) generating a uniform wide-angle light field and a light sensor (10) receiving the light source, the single transmitting tube light source (14) and the light sensor (10) are located in the same vertical horizontal plane, the distance between the single transmitting tube light source (14) and the light sensor (10) is calculated by a calculation formula, and the light shielding sheet (4) is located between the single transmitting tube light source (14) and the light sensor (10); The light sensor (10) comprises two rectangular light sensors that are precisely symmetrical and have exactly the same area, and the light shielding sheet (4) cannot completely shield a single rectangular light sensor. 2. A detector for detecting a linear displacement position as described in claim 1, characterized in that the linearly movable element (module 3) is slidably connected to a fixed base (7) via a guide rail assembly (5). 3. A detector for detecting linear displacement position according to claim 1, characterized in that: the top of the fixed base (7) is located at the moving end of the driving module (module 2) to fix the limiting column (6); The limiting column (6) is used to limit the moving distance of the moving end of the driving module (module 2). 4. A detector for detecting a linear displacement position according to claim 1, characterized in that: the detector module (module 1) comprises an outer shell cover (11), and the outer shell cover (11) is fixed on a fixed base (7); A transmitting tube bracket (13) is provided at the bottom of the inner wall of the outer shell cover (11), a light sensor (10) is fixed between the transmitting tube bracket (13) and the outer shell cover (11), and a single transmitting tube light source (14) is fixed at the center position of the top of the transmitting tube bracket (13); A rectangular hole is provided on one side of the outer shell (11) and the linearly movable element (module 3), and a light shielding sheet (4) passes through the rectangular hole and is arranged inside the outer shell (11) and above the light sensor (10). 5. A detector for detecting a linear displacement position as described in claim 4, characterized in that: a window piece (9) is arranged on the top of the light sensor (10), the window piece (9) is located between the light shielding piece (4) and the light sensor (10), and there is no other obstruction in the space between the light shielding piece (4) and the light sensor (10) except the window piece (9). 6. A detector for detecting linear displacement position as described in claim 1, characterized in that the light shielding sheet (4) is made of a material with high hardness, light weight and opaqueness. 7. A detector for detecting linear displacement position according to claim 6, characterized in that: a light homogenizer (15) is provided at the bottom of the single emitting tube light source (14); Wherein, the light homogenizing sheet (15) is fixed on the outer shell cover (11). 8. A detector for detecting linear displacement position according to claim 6, characterized in that: the distance k between the single emitting tube light source (14) and the light sensor (10) is determined by the divergence angle θ of the light source and the width n of the light sensor, and the specific calculation formula is: k=cotangentθ×( ¹ / ₂ ×n).