Coating film thickness measuring instrument comprising automatic calibration assembly

Abstract

The invention provides a coating film thickness measuring instrument comprising an automatic calibration assembly, the coating film thickness measuring instrument comprises a shell, a diaphragm, a light source, a light transmission cylinder, a turntable, a condensing lens and a photoelectric detector, the diaphragm is arranged at the bottom of the shell, and the light source is reflected by a measured coating film to form measuring light so as to enter the light transmission cylinder; a reference optical filter and a measurement optical filter which are arranged in pairs are uniformly arranged on the turntable, and each optical filter can be positioned above the light passing cylinder; light paths passing through the corresponding reference optical filter and the measurement optical filter are focused by the condensing lens and then are respectively imaged to the photoelectric detector; the measuring instrument further comprises an automatic calibration assembly which comprises a calibration plate and a stepping motor. An output shaft of the stepping motor penetrates through the axis of the calibration plate and is connected with the bottom of the shell in a pivoted mode. When automatic calibration is carried out in the embodiment, the stepping motor drives the calibration plate to shield the window sheet, and the processor determines the calibration coefficient according to the spectral intensity passing through the plurality of optical filters.

Description

Technical Field

[0001] The invention relates to the technical field of coating film measurement, in particular to a coating film thickness measuring instrument comprising an automatic calibration component. Background Art

[0002] In the process of measuring the coating thickness, infrared spectroscopy can be used for measurement. That is, according to the infrared absorption characteristics of the oil film surface, infrared energy changes will occur after the infrared light source is irradiated and reflected. By comparing the difference in energy changes, the coating thickness of the corresponding area can be calculated.

[0003] During the measurement process, the photoelectric devices that generate and receive infrared spectra will drift due to the influence of temperature and other factors, which will have a certain impact on the stability and accuracy of the measurement results.

[0004] Accordingly, a calibration component is needed to solve the above problems. Summary of the invention

[0005] The content of the present invention is used to introduce the concepts in a brief form, which will be described in detail in the detailed implementation section below. The content of the present disclosure is not intended to identify the key features or essential features of the technical solution claimed for protection, nor is it intended to limit the scope of the technical solution claimed for protection.

[0006] Some embodiments of the present invention provide a coating thickness measuring instrument including an automatic calibration component to solve the technical problems mentioned in the above background technology section.

[0007] The coating thickness measuring instrument including the automatic calibration component includes a housing and a window piece, a light source, a light tube, a rotating disk, a focusing lens and a photoelectric detector installed in the housing from bottom to top, wherein:

[0008] The window piece is arranged at the bottom of the housing, so that after the focused light source passes through the window piece, it is reflected by the coating film to form a measuring light and enters the light-transmitting tube;

[0009] The rotating disk is evenly provided with reference filters and measurement filters arranged in pairs for coatings with different infrared absorption peaks. As the rotating disk rotates, each filter can be located above the light-transmitting cylinder.

[0010] The condenser lens focuses the light path after passing through the corresponding reference filter and the measurement filter, and images them onto the photodetector to form a reference electrical signal and a measurement electrical signal respectively;

[0011] The housing is also provided with a processor which is in communication with the photoelectric detector, and the processor processes the measurement electrical signal and the reference electrical signal to determine the coating thickness;

[0012] The measuring instrument further comprises an automatic calibration assembly, comprising a calibration plate and a stepper motor; the output shaft of the stepper motor passes through the axis of the calibration plate and is pivotally connected to the bottom of the housing;

[0013] In response to entering into automatic calibration, the stepper motor drives the calibration plate to cover the window plate, and the processor determines the calibration coefficient according to the spectral intensity passing through the multiple filters.

[0014] The above embodiments of the present invention have the following beneficial effects:

[0015] Due to the absorption characteristics of the coating film for infrared light of a specific wavelength, after the light source irradiates the coating film to be measured, the infrared light of a specific wavelength will be absorbed by the coating film. The other wavelengths in the reflected measurement light are then filtered out by the measurement filter, so that the partially absorbed infrared light is imaged on the photodetector to generate a measurement electrical signal. In this way, the setting of the measurement filter can block unnecessary wavelengths, form a monochromatic spectral signal, and thus improve the measurement accuracy.

[0016] The reference filter, which is set in pairs with the measuring filter, can image the wavelengths not absorbed by the coating onto the photodetector to generate a reference electrical signal. By determining the absorbance using the reference electrical signal and the measuring electrical signal collected at the same measuring position and under the same measuring environment on the coating, the influence of the coating surface roughness and the unevenness of the measuring surface can be reduced, thereby improving the measurement accuracy.

[0017] Since multiple pairs of reference filters and measurement filters are provided correspondingly, the photoelectric detector can respectively collect reference electrical signals and measurement electrical signals for a variety of coatings with different infrared absorption peaks, making the measurement more targeted and improving the accuracy of the measurement of different coatings.

[0018] The processor obtains the light intensity of the corresponding wavelength through the reference electrical signal and the measured electrical signal, and determines the absorbance according to the absorbance calculation formula. Finally, according to the Lambert-Beer law, the above absorbance is converted with the absorbance of the standard thickness coating corresponding to the infrared absorption peak to obtain the coating thickness, ensuring the reliability of the measurement principle.

[0019] When the difference between the internal temperature of the measuring instrument and the temperature of the previous calibration exceeds the preset threshold, it indicates that the temperature inside the measuring instrument is too high, which will affect the optoelectronic devices, and the light source and electronic components may drift after the instrument runs continuously for a long time. In order to ensure the stability and accuracy of the measurement results, the measuring instrument is automatically calibrated. The calibration coefficient is determined by comparing the spectral intensity through multiple filters with the standard value, thereby ensuring that the instrument has the same measurement accuracy under any specified conditions of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a structural schematic diagram of an embodiment of a coating thickness measuring instrument including an automatic calibration component of the present invention;

[0022] Figure 2 A schematic diagram of the internal structure of an embodiment of a coating thickness measuring instrument including an automatic calibration component of the present invention;

[0023] Figure 3 It is a schematic diagram of the internal structure of another embodiment of the coating thickness measuring instrument including the automatic calibration component of the present invention;

[0024] Figure 4 It is a schematic diagram of the internal structure of another embodiment of the coating thickness measuring instrument including the automatic calibration component of the present invention;

[0025] Figure 5 It is a schematic diagram of the internal structure of another embodiment of the coating thickness measuring instrument including the automatic calibration component of the present invention.

[0026] Description of reference numerals:

[0027] 11. Housing; 12. Handle; 13. Control button; 14. Display screen;

[0028] 21. Halogen lamp; 22. Reflector cup;

[0029] 3. Window piece;

[0030] 4. Light tube;

[0031] 51. Turntable; 52. Filter; 53. Rotating motor; 54. Photoelectric sensor; 55. Light emitting diode; 56. Positioning hole;

[0032] 6. Focusing lens;

[0033] 7. Photoelectric detector;

[0034] 81. Calibration plate; 82. Stepper motor; 83. Hall sensor; 84. Magnet. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0039] First see Figure 1 , Figure 1 FIG. 1 is a schematic diagram of the structure of an embodiment of a coating thickness measuring instrument including an automatic calibration component of the present invention. Figure 1 As shown, the measuring instrument is provided with a housing 11 and a handle 12 pivotally connected to the housing 11. Specifically, ear shafts are provided on both sides of the upper end of the housing 11, and the two ends of the handle 12 are pivotally connected to the two ear shafts in a one-to-one correspondence. Further, a ball head screw is connected to the ear shaft, and a plurality of slots are provided in a circular array at the connection end of the handle 12. In the assembled state, as the handle 12 rotates, the ball head screw engages with a slot, thereby fixing the rotation angle of the handle 12.

[0040] In addition, a control button 13 and a display screen 14 are also provided on the top of the housing 11. The control button 13 is used to turn on or off the measuring instrument and adjust relevant parameters. The display screen 14 is used to display measurement results or a parameter adjustment interface.

[0041] In some optional implementations, the instrument body is designed to be cylindrical based on the characteristics of the internal light reflection path and comprehensive considerations of the use and post-processing materials.

[0042] It should be noted that the measuring instrument of the present invention is used to measure the thickness of coatings that have absorption characteristics for infrared light of a specific wavelength, which may be various oil films, water films or organic films.

[0043] See next Figures 2 to 5 , Figure 2 A schematic diagram of the internal structure of an embodiment of a coating thickness measuring instrument including an automatic calibration component of the present invention; Figure 3 It is a schematic diagram of the internal structure of another embodiment of the coating thickness measuring instrument including the automatic calibration component of the present invention; Figure 4 It is a schematic diagram of the internal structure of another embodiment of the coating thickness measuring instrument including the automatic calibration component of the present invention; Figure 5 FIG. 2 is a schematic diagram of the internal structure of another embodiment of a coating thickness measuring instrument including an automatic calibration component of the present invention. Figures 2 to 5 As shown, a window sheet 3, a light source, a light tube 4, a rotating disk 51, a focusing lens 6 and a photodetector 7 are installed from bottom to top in the housing 11. The window sheet 3 is arranged at the bottom of the housing 11 so that the light source can pass through the window sheet 3 and project onto the coating film to be measured at the bottom of the measuring instrument.

[0044] The light source can be generated by a halogen lamp 21. A reflector cup 22 can be provided between the halogen lamp 21 and the window sheet 3. The axis of the reflector cup 22 coincides with the optical axis of the light source. The reflector cup 22 makes the light source converge into a uniform light spot. The halogen lamp 21 and the reflector cup 22 can be mounted on a bracket, and the bracket can be fixedly connected to the bottom of the housing 11.

[0045] The light spot passes through the window 3, and after the measured oil film absorbs part of the infrared light, it is reflected to form the measuring light and enters the light tube 4. The window 3 and the light tube 4 can be coaxially arranged, and the optical axis of the measuring light can coincide with the vertical direction.

[0046] The turntable 51 arranged on the light-transmitting cylinder 4 can rotate around its own axis, and four filters 52 are evenly arranged on the turntable 51. The four filters 52 are divided into two pairs, each pair including a reference filter and a measurement filter for different infrared absorption peak coatings. Further, each pair of reference filters and measurement filters are narrow-band infrared filters with similar narrow-band widths.

[0047] By filtering other wavelengths in the reflected measurement light through the measurement filter, the partially absorbed infrared light is imaged onto the photodetector 7 to generate a measurement electrical signal. In this way, the setting of the measurement filter can block unnecessary wavelengths, form a monochromatic spectral signal, and thus improve the measurement accuracy.

[0048] The reference filter can image the wavelengths that are not absorbed by the coating onto the photodetector 7 to generate a reference electrical signal.

[0049] In this way, by determining the absorbance using the reference electrical signal and the measured electrical signal collected at the same measurement position and under the same measurement environment of the coating, the influence of the coating surface roughness and the unevenness of the measurement surface can be reduced, thereby improving the measurement accuracy. Furthermore, when selecting the reference wavelength, the wavelength closest to the measurement wavelength that is not absorbed by the measured coating is selected as the reference wavelength, so that the spectral properties are closer and the compensation effect is the best, thereby improving the measurement accuracy.

[0050] Specifically, the measuring instrument further includes a processor. The processor can be connected to the above-mentioned photodetector 7 in communication. The processor can be an MCU (Microcontroller Unit), a DSP (Digital Signal Process) or an FPGA (Field Programmable Gate Array), etc. After the processor receives the above-mentioned reference electrical signal and the measurement electrical signal, it processes the corresponding light intensity and determines the absorbance according to the following absorbance calculation formula:

[0051] A=log(I 0 / I);

[0052] Where A represents absorbance;

[0053] I 0 Indicates the intensity of the reference light;

[0054] I represents the intensity of the measured light.

[0055] It should be noted that, although the above description is based on four filters 52 as an example, that is, two pairs of reference filters and measurement filters, the absorbance of two coatings with different infrared absorption peaks can be determined. However, the number of filters is not unique, and those skilled in the art can increase the number of reference filters and measurement filters according to actual conditions, so as to determine the absorbance of more types of coatings. Of course, matching reference filters and measurement filters can also be replaced in pairs to determine the absorbance of the target coating, but such changes do not exceed the scope of protection of the present disclosure.

[0056] Specifically, a rotating motor 53 is connected to the bottom of the turntable 51, and the housing 11 of the rotating motor 53 is fixedly connected to the housing 11. In the working state, the rotating motor 53 drives the turntable 51 to rotate, so that the paired filters 52 can be successively located above the light-through holes. In this way, the measurement light passing through the paired filters 52 passes through the condenser lens 6 and is imaged onto the photodetector 7 to form a reference electrical signal and a measurement electrical signal. The above-mentioned light-through tube 4, the condenser lens 6 and the photodetector 7 can be coaxially arranged.

[0057] Furthermore, in order to determine the position of each filter 52 , the rotation angle of the rotary motor 53 may be determined by an encoder in the rotary motor 53 , and different rotation angles correspond to different filters 52 .

[0058] In addition, positioning holes 56 corresponding to the four filters 52 can be evenly arranged on the edge of the rotating disk 51, and photoelectric sensors 54 and light-emitting diodes 55 are respectively arranged above and below the rotating disk 51. Specifically, as the positioning holes 56 rotate, when the light emitted by the light-emitting diode 55 passes through the positioning holes 56 and is projected onto the photoelectric sensor 54, the photoelectric sensor 54 senses a change in the light signal, which indicates that the positioning hole 56 passes through the photoelectric sensor 54. At this time, the filter 52 corresponding to the positioning hole 56 can be arranged to rotate above the light-transmitting cylinder 4. Of course, the rotating disk 51 can be set to an initial position, and the positioning holes 56 can be marked as 1-4 in the order in which the photoelectric sensor 54 detects the positioning holes 56. In this way, the corresponding two groups of filters 52 can be numbered, and the corresponding filters 52 can be controlled to rotate above the light-transmitting cylinder 4.

[0059] According to Lambert-Beer's law, absorbance is proportional to coating thickness. Therefore, the absorbance of a coating with the same standard thickness as the current infrared absorption peak can be determined through repeated experiments, and the absorbance obtained by processing can be converted to the absorbance of the coating with the standard thickness, and the thickness of the coating to be measured can be obtained based on the thickness of the coating with the standard thickness.

[0060] See also Figures 2 to 5 The coating thickness measuring instrument also includes an automatic calibration component, including a calibration plate and a stepper motor, a temperature sensor and a Hall sensor that are communicatively connected to the processor. The output shaft of the stepper motor passes through the axis of the calibration plate and is pivotally connected to the bottom of the housing. The stepper motor can drive the calibration plate to rotate around its own axis. Notches are provided on both sides of the calibration plate. When measuring the thickness of the target coating film, the notches of the calibration plate rotate to above the window sheet, so that the calibration plate does not block the light source emitted by the halogen lamp.

[0061] It should be noted that the measuring instrument will enter automatic calibration under three circumstances. First, after the measuring instrument is powered on and initialized, automatic calibration is performed to ensure the accuracy of subsequent thickness measurements. Second, when the measuring instrument runs for more than a preset time, automatic calibration is performed. The above-mentioned preset time can be determined by technicians in this field through repeated experiments, for example, it can be 30 minutes, or 40 minutes, etc. Third, if the difference between the temperature inside the measuring instrument and the temperature of the previous calibration exceeds the preset threshold, automatic calibration is performed. For example, the above-mentioned preset threshold is set to 10°C, and the processor can determine the temperature inside the shell during the previous calibration through the temperature sensor set in the shell, for example, 20°C. During the thickness measurement process, the temperature sensor monitors the temperature inside the shell in real time. If the temperature inside the shell is higher than 30°C, the processor determines that the temperature difference exceeds the preset threshold. At this time, the thickness measurement work will be stopped and automatic calibration will be entered. The above-mentioned prefabrication can also be determined by technicians in this field through repeated experiments.

[0062] During automatic calibration, first, the processor stops the measurement process and controls the stepper motor 82 to rotate, thereby driving the calibration plate 81 to cover the window sheet 3. The Hall sensor 83 can be mounted on the calibration plate 81 through a bracket, and a magnet 84 is fixed on the calibration plate 81.

[0063] The specific positions of the Hall sensor 83 and the magnet 84 are set as follows: when the calibration plate 81 reaches the calibration position, the Hall sensor 83 detects the magnet 84. At this time, the magnetic field detected by the Hall sensor changes, and a voltage signal is sent to the processor. The setting of the positions of the Hall sensor 83 and the magnet 84 enables the calibration plate 81 to remove the shielding of the window plate 3, and the measuring instrument can measure the coating thickness normally. Fixedly rotating a certain angle at this position can enable the calibration plate 81 to completely shield the window plate 3, and enable the light source generated by the halogen lamp 21 to illuminate the same calibration position of the calibration plate 81 during each calibration.

[0064] After determining that the calibration plate 81 reaches the calibration position, the halogen lamp 21 is turned on so that the focused light spot hits the calibration plate 81. At this time, the spectrum information received by the photodetector 7 is the spectrum of the light source after being reflected by the calibration plate 81.

[0065] The spectral signals passing through the four groups of narrow-band filters are sampled. By adjusting the intensity of the light source, the intensity of the spectrum with the most significant signal characteristics among the four spectral signals reaches a preset value, so that the measuring instrument can output a consistent spectral signal intensity. Those skilled in the art can determine the above preset value through repeated experiments.

[0066] Next, the four spectral signal intensities under the current conditions are sampled, and the instrument spectral characteristic coefficient under the current conditions is calculated using the relevant formula, which reflects the spectral response characteristics under the current environmental conditions.

[0067] Then, a calibration factor is obtained by performing a proportional correction based on the current instrument spectral characteristic coefficient and the instrument spectral characteristic coefficient under standard conditions. The calibration factor is used to adjust the output of the measuring instrument to ensure that the instrument has the same measurement accuracy under any specified conditions of use.

[0068] Finally, the stepper motor 82 is started to rotate the calibration plate 81 back to the initial position, that is, the position where the window sheet 3 is not blocked, and then the measurement process can be continued.

[0069] 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.

Claims

1. A coating thickness measuring instrument including an automatic calibration component, characterized in that: It comprises a housing and a window piece, a light source, a light tube, a rotating disk, a focusing lens and a photodetector installed in the housing from bottom to top, wherein: The window piece is arranged at the bottom of the housing, so that after the focused light source passes through the window piece, it is reflected by the coating film to form a measuring light and enters the light-transmitting tube; The rotating disk is evenly provided with reference filters and measurement filters arranged in pairs for coatings with different infrared absorption peaks. As the rotating disk rotates, each filter can be located above the light-transmitting cylinder. The condenser lens focuses the light path after passing through the corresponding reference filter and the measurement filter, and images them onto the photodetector to form a reference electrical signal and a measurement electrical signal respectively; The housing is also provided with a processor which is in communication with the photoelectric detector, and the processor processes the measurement electrical signal and the reference electrical signal to determine the coating thickness; The measuring instrument further comprises an automatic calibration assembly, comprising a calibration plate and a stepper motor; the output shaft of the stepper motor passes through the axis of the calibration plate and is pivotally connected to the bottom of the housing; In response to entering automatic calibration, the stepper motor drives the calibration plate to cover the window plate, and the processor determines the calibration coefficient according to the spectral intensity passing through the multiple filters.

2. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: In response to the measuring instrument being started and initialized, or the measuring instrument running for more than a preset time, or the difference between the temperature in the measuring instrument and the temperature of the previous calibration exceeds a preset threshold, entering automatic calibration; During the automatic calibration process, the processor samples the spectral signal passing through the reference filter and the measurement filter; By adjusting the intensity of the light source, the intensity of the spectrum with the most significant signal characteristics among the multiple spectral signals reaches a preset value; Sample multiple spectral signal intensities under current conditions to determine the instrument spectral characteristic coefficients; The calibration coefficient is obtained by performing proportional correction based on the current instrument spectral characteristic coefficient and the instrument spectral characteristic coefficient under standard conditions.

3. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: A temperature sensor is disposed in the housing and is communicatively connected to the processor.

4. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: A magnet is arranged on the calibration plate, and a Hall sensor is mounted on the calibration plate. The Hall sensor rotates the calibration plate to block the window piece to locate the calibration position of the calibration plate or removes the blocking to measure the coating thickness according to the induction state of the magnet.

5. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: The window piece, the light-transmitting tube, the condensing lens and the photoelectric detector are coaxially arranged.

6. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: A rotating motor is connected to the bottom of the turntable, and the outer shell of the rotating motor is fixedly connected to the housing; in a working state, the rotating motor drives the turntable to rotate, so that the reference filter and the measurement filter arranged in pairs can be successively located above the light-through hole.

7. The coating thickness measuring instrument including an automatic calibration component according to claim 1, characterized in that: Positioning holes corresponding to each measuring filter and reference filter are evenly arranged on the edge of the rotating disk; photoelectric sensors and light emitting diodes for detecting the positioning holes are arranged on the upper and lower sides of the rotating disk.

8. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: The shell is cylindrical.

9. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: A handle is also provided at the upper end of the shell, and a plurality of slots are arranged in a circular array at the connecting end of the handle; ear shafts are provided on both sides of the shell, and a ball head screw is connected to each ear shaft; in the assembled state, the connecting end of the handle is pivotally connected to the two ear shafts, and as the handle rotates, the ball head screw engages with a slot to fix the rotation angle of the handle.

10. The coating thickness measuring instrument including the automatic calibration component according to claim 1, characterized in that: The upper end surface of the shell is provided with control buttons and a display screen.

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