Contact type ultra-high precision micrometer based on PSD principle

Abstract

The invention discloses a PSD principle-based contact type ultra-high precision micrometer, which comprises a product shell, a cover plate is mounted at the top of the product shell through a screw, a laser head bracket and a precision ball sliding group are mounted on the inner wall of the product shell, a laser emission head is mounted in the middle of the laser head bracket, and a precision ball sliding group is mounted in the middle of the precision ball sliding group. A prism support is installed on the surface of a sliding block of the precise ball sliding set through a screw, an internal reflection prism is installed at the end, facing the laser emission head, of the prism support, and a ball bush assembly is installed at one end of the product shell. The PSD photoelectric position detection technology is adopted, the displacement of a laser incidence point is directly calculated through the semiconductor transverse photoelectric effect, the theoretical resolution can reach 0.05 micron, the response speed is increased to 500 Hz or above and is far higher than that of a traditional mechanical micrometer and a traditional grating type displacement sensor, and the ultra-precision machining requirement can be met.

Description

Technical Field

[0001] The present invention relates to the field of high-precision measurement technology, and in particular to a contact-type ultra-high-precision micrometer based on the PSD principle. Background Art

[0002] Traditional mechanical micrometers (such as micrometers) rely on manual readings and have limited accuracy (usually 1μm). Traditional grating displacement sensors rely on the principle of Moiré fringe counting, and their resolution is limited by the grating pitch (currently the highest is about 0.2μm). In addition, the dynamic response speed of traditional grating displacement sensors is ≤100Hz, which makes it difficult to meet the needs of high-speed production lines. High-precision displacement sensors have the characteristics of fast measurement speed, wide spectrum response, high resolution, and high real-time performance. Their minimum resolution rate has been increased to the nanometer level (0.05μm or even higher), which can meet the needs of ultra-precision machining.

[0003] Therefore, it is necessary to invent a contact-type ultra-high precision micrometer based on the PSD principle to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a contact type ultra-high precision micrometer based on the PSD principle to solve the problems in the above technology.

[0005] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: a contact type ultra-high precision micrometer based on the PSD principle, comprising a product housing, a cover plate is installed on the top of the product housing by screws, a laser head bracket and a precision ball slide group are installed on the inner wall of the product housing, a laser transmitter head is installed in the middle of the laser head bracket, a prism bracket is installed on the slider surface of the precision ball slide group by screws, an internal reflection prism is installed on the end of the prism bracket facing the laser transmitter head, a ball bushing assembly is installed at one end of the product housing, one end of the guide rod of the ball bushing assembly extends to the interior of the product housing and is fixedly connected to one end of the prism bracket by screws, a high-toughness reset spring is provided inside the product housing, one end of the high-toughness reset spring is installed on the inner wall of the product housing by screws, and the other end of the high-toughness reset spring is installed on the surface of the prism bracket by screws;

[0006] A PCBA printed circuit board is installed on the inner bottom surface of the product shell by screws. A PSD sensor, a precision instrument amplifier circuit, a high-speed sampling dual-channel synchronous ADC, an embedded processing chip and an RS422 interface are provided on the surface of the PCBA printed circuit board. The output end of the PSD sensor is electrically connected to the input end of the precision instrument amplifier circuit, the output end of the precision instrument amplifier circuit is electrically connected to the input end of the high-speed sampling dual-channel synchronous ADC, the output end of the high-speed sampling dual-channel synchronous ADC is electrically connected to the input end of the embedded processing chip, the output end of the embedded processing chip is electrically connected to the input end of the RS422 interface, and the output end of the RS422 interface can be connected to a user-end device.

[0007] Preferably, the internal reflection prism is a right-angle prism made of K9 material with a refractive index of 1.516.

[0008] Preferably, the laser emitter head can emit a straight-line visible laser line with real-time changing power and period according to actual instructions. The laser line enters the internal reflection prism and is vertically irradiated on the surface of the PSD sensor after internal reflection. This laser is visible light, and the emitted light is a straight line with a wavelength of 940nm. The optical lens of the laser emitter head emits the laser straight line with the best focus and the thinnest line in the range of 10-30mm, and the measurement accuracy is the best. Controlling the total length of the optical path within 30mm can reduce air disturbance.

[0009] Preferably, after the guide rod is pushed by an external force to cause the prism bracket and the internal reflection prism to move on the precision ball slide assembly, the position of the laser line reflected by the internal reflection prism hitting the surface of the PSD sensor will also change.

[0010] Preferably, after receiving the reflected laser line, the PSD sensor generates two photocurrent signals in opposite directions using the semiconductor lateral photoelectric effect. The two photocurrent signals are converted into two voltage signals through a precision instrument amplifier circuit and then input into a high-speed sampling dual-channel synchronous ADC.

[0011] Preferably, the high-speed sampling dual-channel synchronous ADC performs analog-to-digital conversion on the two input voltage signals, and the converted digital signals are acquired and processed by the embedded processing chip.

[0012] Preferably, the embedded processing chip performs digital filtering, spectrum analysis, state feature extraction, calculation model algorithm and other processing on the digital signal, and finally calculates the relative position of the internal reflection prism, and outputs the Modbus protocol signal chain through the RS422 interface to the user end for reading and writing.

[0013] Preferably, an anti-diffuse reflection cover is installed at the bottom of the prism bracket by screws, and a through hole No. 1 is opened on the surface of the anti-diffuse reflection cover, and the through hole No. 1 is located directly below the internal reflection prism.

[0014] Preferably, a transmissive cover is installed on the top of the PSD sensor, and the transmissive cover is located below the anti-diffuse reflection cover. A second through hole is opened on the surface of the transmissive cover. After reflection by the internal reflection prism, the laser line can pass through the first through hole and the second through hole in sequence and irradiate the surface of the PSD sensor vertically.

[0015] Preferably, the coordinated use of the anti-diffuse reflection cover and the transmissive cover plate can suppress diffuse reflection, reduce dark current generated by useless light, and avoid increasing measurement errors.

[0016] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0017] 1. This invention uses PSD photoelectric position detection technology to directly calculate the displacement of the laser incident point through the semiconductor transverse photoelectric effect. The theoretical resolution can reach 0.05μm, and the response speed is increased to over 500Hz, which is much higher than traditional mechanical micrometers and traditional grating displacement sensors, and can meet the needs of ultra-precision machining.

[0018] 2. The design of the precision ball slide and ball bushing assembly replaces sliding friction with rolling friction, significantly reducing mechanical resistance. The prism bracket moves smoothly under the push of the guide rod, avoiding the displacement hysteresis or error caused by friction in traditional sliding structures.

[0019] 3. By using the anti-diffuse reflection cover and the transmissive cover together, diffuse reflection is suppressed, dark current generated by useless light is reduced, and measurement errors are avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention after the cover plate is removed;

[0021] Figure 2 This is a schematic diagram of the overall structure of the present invention when the cover plate is not removed;

[0022] Figure 3 This is a cross-sectional view of the structure after the cover plate of the present invention is removed;

[0023] Figure 4 Schematic diagram of the structure of the prism bracket and the internal reflection prism of the present invention;

[0024] Figure 5 A first perspective view of a local structure of the present invention;

[0025] Figure 6 A second perspective view of the local structure of the present invention;

[0026] Figure 7 This is a schematic structural diagram of the precision ball bearing slide assembly, prism bracket, and anti-diffuse reflection cover of the present invention;

[0027] Figure 8 This is a schematic structural diagram of the PCBA printed circuit board and the transmissive cover plate of the present invention;

[0028] Figure 9 This is a schematic structural diagram of the PCBA printed circuit board of the present invention;

[0029] Figure 10 This is a block diagram of the signal processing system based on the PSD sensor of the present invention.

[0030] Description of reference numerals:

[0031] 1. Product housing; 2. Cover; 3. Laser head bracket; 4. Precision ball slide group; 5. Laser emitter head; 6. Slider; 7. Prism bracket; 8. Internal reflection prism; 9. Ball bushing assembly; 10. Guide rod; 11. High-toughness reset spring; 12. PCBA printed circuit board; 13. PSD sensor; 14. Precision instrument amplifier circuit; 15. High-speed sampling dual-channel synchronous ADC; 16. Embedded processing chip; 17. RS422 interface; 18. Anti-diffuse reflection cover; 19. Through hole No. 1; 20. Transmissive cover; 21. Through hole No. 2. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] The present invention provides Figure 1-10 A contact ultra-high precision micrometer based on the PSD principle is shown, comprising a product housing 1, a cover plate 2 being mounted on the top of the product housing 1 by screws, a laser head bracket 3 and a precision ball slide group 4 being mounted on the inner wall of the product housing 1, a laser transmitter 5 being mounted in the middle of the laser head bracket 3, a prism bracket 7 being mounted on the surface of the slider 6 of the precision ball slide group 4 by screws, an internal reflection prism 8 being mounted on the end of the prism bracket 7 facing the laser transmitter 5, a ball bushing assembly 9 being mounted on one end of the product housing 1, one end of a guide rod 10 of the ball bushing assembly 9 extending into the interior of the product housing 1 and being fixedly connected to one end of the prism bracket 7 by screws, a high-toughness reset spring 11 being arranged inside the product housing 1, one end of the high-toughness reset spring 11 being mounted on the inner wall of the product housing 1 by screws, and the other end of the high-toughness reset spring 11 being mounted on the surface of the prism bracket 7 by screws;

[0034] A PCBA printed circuit board 12 is installed on the inner bottom surface of the product housing 1 by screws. A PSD sensor 13, a precision instrument amplifier circuit 14, a high-speed sampling dual-channel synchronous ADC15, an embedded processing chip 16 and an RS422 interface 17 are provided on the surface of the PCBA printed circuit board 12. The output end of the PSD sensor 13 is electrically connected to the input end of the precision instrument amplifier circuit 14, the output end of the precision instrument amplifier circuit 14 is electrically connected to the input end of the high-speed sampling dual-channel synchronous ADC15, the output end of the high-speed sampling dual-channel synchronous ADC15 is electrically connected to the input end of the embedded processing chip 16, the output end of the embedded processing chip 16 is electrically connected to the input end of the RS422 interface 17, and the output end of the RS422 interface 17 can be connected to the user-end device.

[0035] In one aspect of this embodiment, the internal reflection prism is a right-angle prism made of K9 material with a refractive index of 1.516. The laser emission head 5 can emit a straight visible laser line with real-time changing power and period according to actual instructions. The laser line enters the internal reflection prism 8 and is vertically irradiated on the surface of the PSD sensor 13 after internal reflection. This laser is visible light and the light emitted is a straight line with a wavelength of 940nm. The optical lens of the laser emission head 5 has the best focusing degree and the thinnest line in the range of 10-30mm, and the measurement accuracy is the best, which can be used to adjust the optical path. Controlling the total length within 30 mm can reduce air disturbance. After the guide rod 10 is pushed by an external force, causing the prism bracket 7 and the internal reflection prism 8 to move on the precision ball slide group 4, the position of the laser line reflected by the internal reflection prism 8 hitting the surface of the PSD sensor 13 will also change. After receiving the reflected laser line, the PSD sensor 13 uses the semiconductor lateral photoelectric effect to generate two photocurrent signals in opposite directions. The two photocurrent signals are converted into two voltage signals by the precision instrument amplifier circuit 14 and then input into the high-speed sampling dual-channel synchronous ADC15. The high-speed sampling dual-channel synchronous ADC15 performs analog-to-digital conversion on the input two voltage signals. The converted digital signals are acquired and processed by the embedded processing chip 16. The embedded processing chip 16 performs digital filtering, spectrum analysis, state feature extraction, calculation model algorithm and other processing on the digital signals, and finally calculates the relative position of the internal reflection prism 8, and outputs the Modbus protocol signal chain through the RS422 interface 17 for the user to read and write. An anti-diffuse reflection cover 18 is installed on the bottom of the prism bracket 7 by screws. The anti-diffuse reflection cover 18 represents A through hole No. 1 19 is provided on the surface, and the through hole No. 1 19 is located directly below the internal reflection prism 8. A transparent cover 20 is installed on the top of the PSD sensor 13, and the transparent cover 2 is located below the anti-diffuse reflection cover 18. A through hole No. 21 is provided on the surface of the transparent cover 20. After reflection by the internal reflection prism 8, the laser line can pass through the through hole No. 1 19 and the through hole No. 2 21 in sequence and irradiate the surface of the PSD sensor 13 vertically. The coordinated use of the anti-diffuse reflection cover 18 and the transparent cover 20 can achieve diffuse reflection suppression, reduce the dark current generated by useless light, and avoid larger measurement errors.

[0036] The precision ball slide group 4, laser transmitter head 5, ball bushing assembly 9, high-toughness reset spring 11, PCBA printed circuit board 12, PSD sensor 13, precision instrument amplifier circuit 14, high-speed sampling dual-channel synchronous ADC 15, embedded processing chip 16 and RS422 interface 17 mentioned in the above content are all existing technical products, and their specific structures and functions are not repeated here.

[0037] Working principle of the present invention:

[0038] Refer to the instruction manual Figure 1-10When using the present invention, first, the micrometer is installed at the key measurement position of the production line. The laser emission head 5 emits a straight-line visible laser line with real-time changing power and period according to actual instructions. After the laser line enters the internal reflection prism 8, it is vertically irradiated on the surface of the PSD sensor 13 through internal reflection.

[0039] When the guide rod 10 is pushed by an external force, it drives the prism holder 7 and the internal reflection prism 8 to move on the precision ball slide 4. This movement causes the position of the laser line reflected by the internal reflection prism 8 on the surface of the PSD sensor 13 to change;

[0040] The PSD sensor 13 receives the reflected laser line and uses the semiconductor transverse photoelectric effect to generate two photocurrent signals in opposite directions. The two photocurrent signals are then converted into two voltage signals through the precision instrument amplifier circuit 14. The high-speed sampling dual-channel synchronous ADC 15 performs analog-to-digital conversion on the input two voltage signals, converting the analog signals into digital signals for subsequent processing. The embedded processing chip 16 performs digital filtering, spectrum analysis, state feature quantity extraction, and calculation model algorithm on the converted digital signals, and finally calculates the relative position of the internal reflection prism 8. The embedded processing chip 16 outputs a Modbus protocol signal chain through the RS422 interface 17 and transmits the calculated position information to the user-end device for reading and writing;

[0041] After the external force disappears, the guide rod 10 is reset under the pull of the high-toughness reset spring 11, driving the prism bracket 7 and the internal reflection prism 8 back to the initial position, waiting for the next measurement operation;

[0042] An anti-diffuse reflection cover 18 is installed at the bottom of the prism bracket 7, and a transmissive cover 20 is installed on the top of the PSD sensor 13. The two are used in conjunction with the No. 1 through hole 19 and the No. 2 through hole 21 to ensure that the laser line can be vertically irradiated on the surface of the PSD sensor 13, while achieving diffuse reflection suppression, reducing the dark current generated by useless light, and avoiding larger measurement errors.

Claims

1. A contact type ultra-high precision micrometer based on the PSD principle, comprising a product housing (1), characterized in that: The top of the product housing (1) is mounted with a cover plate (2) by screws, the inner wall of the product housing (1) is mounted with a laser head bracket (3) and a precision ball sliding group (4), the middle of the laser head bracket (3) is mounted with a laser emitting head (5), the surface of the slider (6) of the precision ball sliding group (4) is mounted with a prism bracket (7) by screws, the end of the prism bracket (7) facing the laser emitting head (5) is mounted with an internal reflection prism (8), one end of the product housing (1) is mounted with a ball bushing assembly (9), one end of the guide rod (10) of the ball bushing assembly (9) extends into the interior of the product housing (1) and is fixedly connected to one end of the prism bracket (7) by screws, a high-toughness reset spring (11) is arranged inside the product housing (1), one end of the high-toughness reset spring (11) is mounted on the inner wall of the product housing (1) by screws, and the other end of the high-toughness reset spring (11) is mounted on the surface of the prism bracket (7) by screws; A PCBA printed circuit board (12) is mounted on the inner bottom surface of the product housing (1) by screws. A PSD sensor (13), a precision instrument amplifier circuit (14), a high-speed sampling dual-channel synchronous ADC (15), an embedded processing chip (16) and an RS422 interface (17) are arranged on the surface of the PCBA printed circuit board (12). The output end of the PSD sensor (13) is electrically connected to the input end of the precision instrument amplifier circuit (14), the output end of the precision instrument amplifier circuit (14) is electrically connected to the input end of the high-speed sampling dual-channel synchronous ADC (15), the output end of the high-speed sampling dual-channel synchronous ADC (15) is electrically connected to the input end of the embedded processing chip (16), the output end of the embedded processing chip (16) is electrically connected to the input end of the RS422 interface (17), and the output end of the RS422 interface (17) can be connected to a user terminal device.

2. The contact type ultra-high precision micrometer based on the PSD principle according to claim 7, characterized in that: The internal reflection prism is a right-angle prism made of K9 material with a refractive index of 1.

516.

3. The contact type ultra-high precision micrometer based on the PSD principle according to claim 1, characterized in that: The laser emitting head (5) can emit a straight visible laser line with real-time power and period changes according to actual instructions. The laser line enters the internal reflection prism (8) and is vertically irradiated on the surface of the PSD sensor (13) after internal reflection. This laser is visible light, and the emitted light is a straight line with a wavelength of 940nm. The optical lens of the laser emitting head (5) has the best focusing degree and the thinnest line in the range of 10-30mm, and the measurement accuracy is the best. Controlling the total length of the optical path within 30mm can reduce air disturbance.

4. The contact type ultra-high precision micrometer based on the PSD principle according to claim 3, characterized in that: When the guide rod (10) is pushed by an external force and the prism bracket (7) and the internal reflection prism (8) move on the precision ball slide assembly (4), the position where the laser line reflected by the internal reflection prism (8) hits the surface of the PSD sensor (13) will also change.

5. The contact type ultra-high precision micrometer based on the PSD principle according to claim 4, characterized in that: After receiving the reflected laser beam, the PSD sensor (13) generates two photocurrent signals in opposite directions by utilizing the semiconductor transverse photoelectric effect. The two photocurrent signals are converted into two voltage signals by a precision instrument amplifier circuit (14) and then input into a high-speed sampling dual-channel synchronous ADC (15).

6. The contact type ultra-high precision micrometer based on the PSD principle according to claim 5, characterized in that: The high-speed sampling dual-channel synchronous ADC (15) performs analog-to-digital conversion on the two input voltage signals, and the converted digital signals are acquired and processed by the embedded processing chip (16).

7. The contact type ultra-high precision micrometer based on the PSD principle according to claim 6, characterized in that: The embedded processing chip (16) performs digital filtering, spectrum analysis, state feature quantity extraction, calculation model algorithm and other processing on the digital signal, and finally calculates the relative position of the internal reflection prism (8), and outputs the Modbus protocol signal chain to the user end for reading and writing through the RS422 interface (17).

8. The contact type ultra-high precision micrometer based on the PSD principle according to claim 1, characterized in that: An anti-diffuse reflection cover (18) is installed on the bottom of the prism bracket (7) by screws. A first through hole (19) is provided on the surface of the anti-diffuse reflection cover (18). The first through hole (19) is located directly below the internal reflection prism (8).

9. The contact type ultra-high precision micrometer based on the PSD principle according to claim 8, characterized in that: A transmissive cover plate (20) is installed on the top of the PSD sensor (13), and the transmissive cover plate (2) is located below the anti-diffuse reflection cover (18). A second through hole (21) is opened on the surface of the transmissive cover plate (20). After being reflected by the internal reflection prism (8), the laser line can pass through the first through hole (19) and the second through hole (21) in sequence and irradiate the surface of the PSD sensor (13) vertically.

10. The contact type ultra-high precision micrometer based on the PSD principle according to claim 9, characterized in that: The coordinated use of the anti-diffuse reflection cover (18) and the transmissive cover plate (20) can suppress diffuse reflection, reduce dark current generated by useless light, and avoid increasing measurement errors.

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