Correction method of lens test station

Abstract

The invention relates to a correction method of a lens test station, which comprises the following steps of: aligning a correction lens with a test image, and returning the shooting times of a correction image to zero; shooting the test image and capturing an image for correction; calculating a center coordinate of the correction image, calculating and storing an offset of the center coordinate relative to the original center coordinate, and adding one to the shooting times of the correction image; and comparing whether the corrected image shooting times are smaller than the preset shooting times, calculating the average offset when the corrected image shooting times are equal to the preset shooting times, and adding the average offset to the original center coordinate to obtain a corrected original center coordinate, the corrected original center coordinate is an index for judging whether the to-be-detected lens passes the test or not.

Description

Technical Field

[0001] This case relates to a lens testing station, in particular to a calibration method for a lens testing station that can correct its own setting changes. Background Art

[0002] Currently, the quality requirements for lens products on the factory production line are strict. Each lens to be shipped out of the factory needs to meet the conditions of high precision and low error tolerance, so that the lens testing station for testing lenses must be a platform with stable environment and high testing reliability.

[0003] As Figure 1 shown, the lens testing station includes: a base, a lens actuator assembly, a lens fixing seat, an image capturing unit, a target actuator assembly, and a control unit (not shown in the figure). Through the controllable lens actuator assembly and the target actuator assembly, the lens testing station can test various lenses of different specifications without repeatedly modifying the structure of the lens testing station. However, after the lens testing station has been operating for a long time, components such as the lens actuator assembly, the target actuator assembly, or the lens fixing seat will generate errors due to the running deviation of the servo motor or the wear of the mechanism itself. In the existing method, it is necessary to measure the rotational error of each servo motor and modify the drive parameters of all servo motors one by one to ensure the correctness of the test results obtained by the lens testing station. However, the lens testing station on the production line usually needs to be calibrated once a week, and each manual calibration of the lens testing station takes a lot of time, thus resulting in poor efficiency of factory operations.

[0004] Therefore, it is necessary to provide a calibration method for a lens testing station that can quickly self-calibrate the setting changes of the lens testing station to reduce the time for calibration operations and improve the efficiency of factory operations. Summary of the Invention

[0005] The object of the present invention is to provide a calibration method for a lens test station. The lens test station includes: a base; a control unit provided with a storage medium and a user interface, the storage medium storing a preset number of shooting times and an original center coordinate; a lens actuator assembly fixed on the base and electrically connected to the control unit; a target actuator assembly arranged on one side of the base and electrically connected to the control unit, and the target actuator assembly is provided with a test image; a lens fixing seat arranged on the lens actuator assembly; and an image capturing unit arranged on the lens fixing seat and electrically connected to the control unit, and located on the optical axis of a calibration lens to capture an image through the calibration lens, and the calibration method of the lens test station includes the following steps: (S20) Control the lens actuator assembly and the target actuator assembly via the control unit according to a preset data, align the calibration lens with the test image, and reset the number of times of shooting a calibration image, and then execute step S21; (S21) Shoot the test image through the calibration lens and the image capturing unit, capture the calibration image through the image capturing unit, and transmit it to the control unit, and then execute step S22; (S22) Calculate a center coordinate of the calibration image via the control unit, calculate an offset of the center coordinate with respect to the original center coordinate and store the offset in the storage medium, and then the control unit accumulatively adds one to the number of times of shooting the calibration image and executes step S23; (S23) Compare via the control unit whether the number of times of shooting the calibration image is less than the preset number of shooting times. When the number of times of shooting the calibration image is less than the preset number of shooting times, execute step S21. When the number of times of shooting the calibration image is equal to the preset number of shooting times, execute step S31; (S31) Calculate all the stored offsets via the control unit to obtain an average offset, and then add the average offset to the original center coordinate to obtain a calibrated original center coordinate and store it in the storage medium. Then, when the lens test station tests a lens to be detected, the control unit uses the calibrated original center coordinate to replace the original center coordinate to perform the test of the lens test station.

[0006] In some embodiments, the original center coordinate is obtained by the control unit calculating the center points of the images generated by a plurality of calibration lenses when the lens test station is initially established.

[0007] In some embodiments, the calibration lens is a lens that has been inspected and assembled correctly.

[0008] In some embodiments, the storage medium further stores a preset warning count, and the calibration method of the lens test station further includes a regular calibration step, which includes: recording, by the control unit, an accumulated test count of the lens test station, and when the accumulated test count reaches the preset warning count, displaying, on the user interface, a warning message asking whether to agree to calibrate the lens test station, and waiting for a user input.

[0009] In some embodiments, the initial value of the accumulated test count is zero, and the control unit increments the accumulated test count by one when the lens test station completes one lens test run.

[0010] In some embodiments, when the control unit receives the user input agreeing to calibrate the lens test station, it calibrates the lens test station and resets the accumulated test count of the lens test station to zero.

[0011] In some embodiments, the lens actuator assembly includes a first linear slide rail parallel to the upper surface of the base; a second linear slide rail connected to the slider of the first linear slide rail and the track of the second linear slide rail is perpendicular to the track of the first linear slide rail; a first turntable connected to the slider of the second linear slide rail and the rotation axis of the first turntable is perpendicular to the upper surface of the base; and a second turntable connected to the disk surface of the first turntable and the rotation axis of the second turntable is perpendicular to the rotation axis of the first turntable, wherein the first linear slide rail, the second linear slide rail, the first turntable and the second turntable are all driven by servo motors to enable the lens fixing seat to rotate in a specified direction according to instructions.

[0012] In some embodiments, the target actuator assembly includes a third linear slide rail and a third turntable disposed on the slider of the third linear slide rail, and the third linear slide rail and the third turntable are both driven by servo motors to adjust the distance and relative angle between the test image and the lens fixing seat.

[0013] As described above, the calibration method for the lens test station in this case averages the offsets obtained from multiple shots by the control unit, writes the average offset to obtain the calibrated original center coordinates, and then tests the lens with the calibrated original center coordinates, which can reduce the time for calibration operations, improve the accuracy and reliability of the lens test station after calibration, and further improve the efficiency of the factory operation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To make the above and other objects, features, advantages and embodiments of the present invention more obvious and understandable, the content of this case can be better understood when read in conjunction with the accompanying drawings.

[0015] Figure 1 It is a structural diagram of the lens test station of the present invention.

[0016] Figure 1A It is a structural diagram of the lens test station of the present invention.

[0017] Figure 1B It is an image captured by the lens to be inspected at the lens test station of the present invention.

[0018] Figure 2 It is a flowchart of the test performed at the lens test station in an embodiment of the present invention.

[0019] Figure 3 It is a flowchart of the calibration of the lens test station in an embodiment of the present invention.

[0020] Figure 4A It is a schematic diagram of the ideal image captured during the calibration of the lens test station in an embodiment of the present invention.

[0021] Figure 4B It is a schematic diagram of the image captured during the calibration of the lens test station in an embodiment of the present invention.

[0022] Figure 5 It is a flowchart of triggering the periodic calibration of the lens test station in an embodiment of the present invention. Detailed implementation manners

[0023] To describe in detail the technical content, structural features, achieved objectives and effects of the calibration method of the lens test station of the present invention, the following examples are given and described in detail in conjunction with the drawings. For the convenience of description, in this patent specification, the upper part is defined as the higher position in the direction facing the drawing, the lower part is defined as the lower position in the direction facing the drawing, the left side is defined as the left hand side position in the direction facing the drawing, and the right side is defined as the right hand side position in the direction facing the drawing.

[0024] Please refer to Figure 1 and Figure 1A as shown, the present invention discloses a calibration method for a lens test station. The lens test station 100 is arranged to test the lens 70 to be detected, and includes: a base 10, a lens actuator assembly 20 fixed on the base 10, a lens fixing seat 30 arranged on the lens actuator assembly 20, an image capturing unit 40 arranged on the lens fixing seat 30, a target actuator assembly 50 arranged on one side of the base 10, a test image 60 arranged on the target actuator assembly 50, and a control unit 80.

[0025] In this embodiment, the lens actuator assembly 20 includes a first linear slide rail 21 with its track parallel to the upper surface of the base 10, a second linear slide rail 22 connected to the slider of the first linear slide rail 21, a first turntable 23 connected to the slider of the second linear slide rail 22, and a second turntable 24 connected to the surface of the first turntable 23. The track of the first linear slide rail 21 is perpendicular to the track of the second linear slide rail 22. The track of the first linear slide rail 21 is set to be left - right direction, and the track of the second linear slide rail 22 is set to be front - back direction. The rotation axis of the first turntable 23 is perpendicular to the upper surface of the base 10. The rotation axis of the second turntable 24 is perpendicular to the rotation axis of the first turntable 23, and the rotation axis of the second turntable 24 is parallel to the track of the first linear slide rail 21. The first linear slide rail 21, the second linear slide rail 22, the first turntable 23 and the second turntable 24 are all driven by servo motors, so that the lens fixing base 30 can be aligned in the specified direction according to the instructions.

[0026] The lens fixing base 30 is arranged on the lens actuator assembly 20 to be aligned in the specified direction according to the instructions under the drive of the lens actuator assembly 20 and is used to fix the lens to be detected 70. In this embodiment, when the slider of the first linear slide rail 21 slides, it drives the lens fixing base 30 to move left or right. When the slider of the second linear slide rail 22 moves, it drives the lens fixing base 30 to move forward or backward. When the surface of the first turntable 23 rotates, it drives the lens fixing base 30 to move up or down. When the surface of the second turntable 24 rotates, it drives the lens fixing base 30 to move slightly left or right. The image capturing unit 40 is arranged on the lens fixing base 30 and on the optical axis of the lens to be inspected 70 to capture images through the lens to be inspected 70.

[0027] The target actuator assembly 50 includes a third linear slide rail 51 and a third turntable 52 arranged on the slider of the third linear slide rail 51. The track of the third linear slide rail 51 is set to be left - right direction. The track of the third linear slide rail 51, the rotation axis of the third turntable 52 and the track of the first linear slide rail 21 are parallel to each other. The third linear slide rail 51 and the third turntable 52 are both driven by servo motors. The movement of the slider of the third linear slide rail 51 drives the test image 60 to move away from or close to the lens fixing base 30, and the rotation of the surface of the third turntable 52 drives the test image 60 to move slightly away from or close to the lens fixing base 30, thereby adjusting the relative distance and relative angle between the test image 60 and the lens fixing base 30.

[0028] Please refer to again Figures 1 to 1A, the control unit 80 is electrically connected to the lens actuator assembly 20 and the target actuator assembly 50 to control the operation of each servo motor in the lens actuator assembly 20 and the target actuator assembly 50. And the control unit 80 is electrically connected to the image capturing unit 40 to receive the inspection image captured by the image capturing unit 40 and calculate the assembly error of the lens 70 to be detected.

[0029] Now, please refer to Figures 1 to 2 , the testing method of the lens testing station 100 includes the following steps: S10: Control and drive the lens actuator assembly 20 and the target actuator assembly 50 via the control unit 80 to align the lens 70 to be detected with the test image 60.

[0030] S11: The image capturing unit 40 and the lens 70 to be detected capture the test image 60 to capture at least one detected image 60' generated through the lens 70 to be detected, and transmit it to the control unit 80. The detected image 60' is the imaging within the visible range of the lens 70 to be detected.

[0031] S12: After receiving the detected image 60' via the control unit 80, calculate the difference between the center coordinates of the detected image 60' and an original center coordinate. The center coordinates of the detected image 60' are the coordinates of the intersection point of two black squares in the detected image 60'. In this embodiment, the original center coordinate is obtained by the control unit 80 calculating the center point of the images generated by multiple calibration lenses (not shown in the figure) fixed to the lens holder 30 when the lens testing station 100 is initially established, where the calibration lens is a lens that has been inspected, assembled correctly, and has almost no error.

[0032] S12’: The control unit 80 determines whether the difference exceeds a threshold value. In practice, the threshold value is 22.6 pixels.

[0033] S13: If the difference exceeds 22.6 pixels, the control unit 80 determines that the lens 70 to be detected fails the test.

[0034] S14: If the difference does not exceed 22.6 pixels, the control unit 80 determines that the lens 70 to be detected passes the test.

[0035] As Figure 4AAs shown, since the calibration lens is a lens that has been inspected, assembled correctly, and has almost no errors, when the lens test station 100 is in a correctly set and error-free state, there are no errors in a standard image 72 captured through the calibration lens, that is, the center coordinates of the standard image 72 coincide exactly with the center coordinates of the test image 60. Therefore, the center coordinates 72a of the standard image 72 are defined as the center coordinates.

[0036] Please refer to again Figures 1 to 1A and Figures 3 to 4B , the calibration method of the lens test station 100 of the present invention includes the following steps: S20’: The operator installs the calibration lens (not shown in the figure) on the lens fixing base 30.

[0037] S20: The control unit 80 controls the lens actuator assembly 20 and the target actuator assembly 50 according to preset data, aligns the calibration lens with the test image 60, resets the number of times of taking a calibration image to zero, and then executes step S21.

[0038] S21: The test image 60 is captured through the calibration lens and the image capturing unit 40, a calibration image 73 is captured by the image capturing unit 40 and transmitted to the control unit 80, and then step S22 is executed.

[0039] S22: The control unit 80 calculates a center coordinate 73a of the calibration image 73, calculates an offset of the center coordinate 73a from the original center coordinate 72a, then the control unit 80 stores the offset in a storage medium accessible by the control unit 80, and then the control unit 80 accumulatively adds one to the number of times of taking the calibration image and executes step S23.

[0040] S23: The control unit 80 compares whether the number of times of taking the calibration image is less than a preset number of times of taking images. When the number of times of taking the calibration image is less than the preset number of times of taking images, step S21 is executed. When the number of times of taking the calibration image is equal to the preset number of times of taking images, step S31 is executed. The number of times of taking the calibration image is the number of times the image capturing unit 40 captures the test image 60 through the calibration lens. In practice, the value of the preset number of times of taking images is set to 15.

[0041] As Figure 4A and Figure 4BAs shown, in the standard image 72 obtained when the lens test station 100 is set correctly without error, the center coordinate 72a of the standard image 72 is almost completely coincident with the image center coordinate of the image 60' to be detected, that is, there is almost no offset between the original center coordinate and the center coordinate of the image 60' to be detected. However, during long-term testing at the lens test station 100, the lens actuator assembly 20 will have operating errors and the lens fixing base 30 itself will be worn out, that is, the lens test station 100 is set with errors, resulting in the deviation of the center coordinate 73a in the calibration image 73 from the center coordinate 72a of the standard image 72, that is, there is an offset between the original center coordinate and the center coordinate 73a of the calibration image 73.

[0042] S31: The control unit 80 calculates the average of all the stored offsets, and then adds the average offset to the original center coordinate to obtain a corrected original center coordinate and stores it in the storage medium. Then, when the lens test station 100 tests the lens 70 to be detected again, the control unit 80 uses the corrected original center coordinate as an index to determine whether the lens 70 to be detected passes the test.

[0043] Compared with the conventional calibration method, the calibration method disclosed in the present invention does not need to find out the errors of each servo motor one by one, nor does it need to adjust the driving parameters of each servo motor one by one. Instead, it directly calculates the final error value obtained by adding the lens actuator assembly and the target actuator assembly, and then directly modifies the coordinate data of the original center in a software correction manner. Therefore, it is much faster than the conventional calibration method.

[0044] Please refer to again Figures 1 to 1A and Figure 5 , the calibration method in the present invention further includes a regular calibration step to keep the settings of the lens test station 100 correct. The regular calibration step includes: S40: The control unit 80 records an accumulated test number of the lens test station 100. The control unit 80 adds one to the accumulated test number when the lens test station 100 completes a lens test on the lens 70 to be detected. The initial value of the accumulated test number is zero. In practice, when the lens test station 100 completes a test, the accumulated test number is incremented by one. That is, when a cycle of steps S10 to S14 is completed in sequence, the accumulated test number is incremented by one.

[0045] S41: When the cumulative number of tests reaches a preset warning number, the control unit 80 controls a user interface to display a warning message for asking whether the operator agrees to calibrate the lens test station 100 and waits for the operator's response. In implementation, the value of the preset warning number is set to 500 according to the actual operation situation of the factory.

[0046] S41': When the control unit 80 receives a user input containing information agreeing to calibrate the lens test station 100, step S42 is executed. When the control unit 80 receives the user input containing information disagreeing to calibrate the lens test station 100, step S43 is executed.

[0047] S42: Calibrate the lens test station 100 and reset the cumulative number of tests of the lens test station 100 to zero. In implementation, when the user determines that the lens test performed by the lens test station 100 is temporarily finished and clicks to agree, the calibration of the lens test station 100 starts.

[0048] S43: The lens test station 100 continues to test the lens 70 to be detected. In implementation, the user may not be able to interrupt or end the test because the lens test station 100 is still performing the test. Therefore, when the user clicks to disagree, the lens test station 100 continues to test the lens 70 to be detected.

[0049] The control unit 80 may be a desktop computer, a notebook computer, or any component or device that includes a screen and a keyboard, is suitable for displaying an interface, can receive the user input, and has functions such as data access, data calculation, data storage, or similar functions, but is not limited thereto.

[0050] In summary, compared with the prior art, the calibration method of the lens test station 100 according to the present invention uses the original center coordinates after calibration as an index for determining whether the lens 70 to be detected passes the test, which can reduce the calibration operation time, improve the accuracy and reliability of the lens test station 100 after calibration, and further improve the efficiency of the factory operation process.

[0051] Although the present case has been disclosed as above with embodiments, it is not intended to limit the present case. Any person with ordinary knowledge in the technical field to which the present case pertains may make some modifications and refinements without departing from the spirit and scope of the present case. Therefore, the protection scope of the present case shall be subject to that defined by the appended claims.

Claims

1. A calibration method for a lens test station, characterized in that: The lens testing station includes: a base; a control unit provided with a storage medium and a user interface, the storage medium storing a preset number of shooting times and an original center coordinate; a lens actuator assembly fixed on the base and electrically connected to the control unit; a target actuator assembly arranged on one side of the base and electrically connected to the control unit, and the target actuator assembly is provided with a test image; a lens fixing seat arranged on the lens actuator assembly; and an image capturing unit arranged on the lens fixing seat and electrically connected to the control unit, and located on the optical axis of a calibration lens to capture an image through the calibration lens, and the calibration method of the lens testing station includes the following steps: (S20) According to a preset data, the control unit controls the lens actuator assembly and the target actuator assembly to align the calibration lens with the test image, and reset the number of calibration image shootings to zero, and then execute step S21; (S21) Shoot the test image through the calibration lens and the image capturing unit, capture the calibration image through the image capturing unit, and transmit it to the control unit, and then execute step S22; (S22) The control unit calculates a center coordinate of the calibration image, calculates an offset of the center coordinate with respect to the original center coordinate, and stores the offset in the storage medium. Then, the control unit accumulatively adds one to the number of calibration image shootings and executes step S23; (S23) The control unit compares whether the number of calibration image shootings is less than the preset number of shooting times. When the number of calibration image shootings is less than the preset number of shooting times, execute step S21. When the number of calibration image shootings is equal to the preset number of shooting times, execute step S31; (S31) The control unit calculates all the stored offsets to obtain an average offset, and then adds the average offset to the original center coordinate to obtain a calibrated original center coordinate and stores it in the storage medium. Then, when the lens testing station tests a lens to be detected, the control unit uses the calibrated original center coordinate to replace the original center coordinate to perform the test of the lens testing station.

2. The calibration method of the lens test station according to claim 1, characterized in that: The original center coordinate is obtained by the control unit calculating the center points of standard images generated by a plurality of the calibration lenses when the lens testing station is initially established.

3. The calibration method of the lens testing station according to claim 1, wherein: The calibration lens is a lens that has been inspected and assembled correctly.

4. The calibration method of the lens testing station according to claim 1, characterized in that: The storage medium further stores a preset warning number, and the calibration method of the lens testing station further includes a regular calibration step, and the regular calibration step includes: the control unit records an accumulated test number of the lens testing station, and when the accumulated test number reaches the preset warning number, a warning message asking whether to agree to calibrate the lens testing station is displayed on the user interface, and wait for a user input.

5. The calibration method of the lens test station according to claim 4, wherein: The initial value of the cumulative test times is zero, and when the lens test at the lens test station is completed once, the control unit increments the cumulative test times by one.

6. The calibration method of the lens test station according to claim 4, wherein: When the control unit receives the user input consenting to calibrate the lens test station, it calibrates the lens test station and resets the cumulative test times of the lens test station to zero.

7. The calibration method of the lens testing station according to claim 1, wherein: The lens actuator assembly includes a first linear slide rail parallel to the upper surface of the base; a second linear slide rail connected to the slider of the first linear slide rail and the track of the second linear slide rail is perpendicular to the track of the first linear slide rail; a first turntable connected to the slider of the second linear slide rail and the rotation axis of the first turntable is perpendicular to the upper surface of the base; and a second turntable connected to the disk surface of the first turntable and the rotation axis of the second turntable is perpendicular to the rotation axis of the first turntable, wherein the first linear slide rail, the second linear slide rail, the first turntable and the second turntable are all driven by servo motors so that the lens holder can rotate in a specified direction according to the instruction.

8. The calibration method of the lens test station according to claim 7, characterized in that: The target actuator assembly includes a third linear slide rail and a third turntable disposed on the slider of the third linear slide rail, and both the third linear slide rail and the third turntable are driven by servo motors to adjust the distance and relative angle between the test image and the lens holder.

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