TWI898414B - Correction method of lens testing station - Google Patents

Abstract

A correction method of lens testing station includes making a correcting lens align a testing pattern and resetting the count of correction image shots to zero; shooting the testing pattern and capturing a correction image; calculating a center coordinates in the correction image, and calculating and saving an offset for the center coordinates to an original center coordinates and then adding one to the count of correction image shots; and comparing whether the count of correction image shots is smaller than a preset count of image shots. Calculate an average offset and add the average offset to the original center coordinates to obtain an original center coordinates corrected when the count of correction image shots is equal to the preset count of image shots. The original center coordinates corrected are indicators to determine whether the lens to be tested passes the test.

Description

Calibration method of lens test station

This case concerns a lens test station, and more particularly, a calibration method for a lens test station capable of correcting for variations in its own settings.

Currently, factories have strict quality requirements for lens products on their production lines. Every lens that leaves the factory must meet high precision and low error tolerance requirements. This requires that the lens testing station used for lens testing must be a platform with a stable environment and high test reliability.

As shown in FIG1 , the lens test station 100 comprises a base 10, a lens actuator assembly 20, a lens mount 30, an image capture unit 40, a target actuator assembly 50, and a control unit (not shown). The controllable lens actuator assembly 20 and target actuator assembly 50 enable the lens test station 100 to test lenses of various specifications without requiring repeated structural modifications. However, after prolonged operation, the lens test station 100 may experience errors in components such as the lens actuator assembly 20, the target actuator assembly 50, or the lens mount 30 due to servo motor operational deviations or wear and tear. Conventional methods require measuring the rotational errors of each servo motor and adjusting the drive parameters of each servo motor individually to ensure accurate test results. However, the lens test station 100 on the production line typically requires weekly calibration. Each manual calibration of the lens test station 100 is time-consuming, resulting in low factory operation efficiency.

Therefore, it is necessary to provide a calibration method for the lens test station 100 that can quickly self-calibrate the lens test station 100's configuration changes to reduce calibration time and improve factory operation efficiency.

The purpose of the present invention is to provide a calibration method for a lens test station, wherein the lens test station comprises: a base; a control unit having a storage medium and a user interface, wherein the storage medium stores a preset number of shots and an original center coordinate; a lens actuator assembly fixed to the base and electrically connected to the control unit; a target actuator assembly disposed on one side of the base and electrically connected to the control unit, wherein the target actuator assembly is provided with a test image; and a lens fixing seat disposed on the lens actuator assembly. and an image capture unit disposed on the lens mount 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. The calibration method of the lens test station includes the following steps: (S20) the control unit controls the lens actuator assembly and the target actuator assembly according to preset data to align the calibration lens with the test image and reset the number of calibration image captures to zero, followed by step S21; (S21) the calibration lens and the image capture unit capture a calibration image. The test image is captured, the correction image is captured by the image capture unit and transmitted to the control unit, and then step S22 is executed; (S22) the control unit calculates a center coordinate of the correction image, and calculates an offset of the center coordinate to the original center coordinate and stores the offset in the storage medium, and then the control unit adds the number of times the correction image is shot and executes step S23; (S23) the control unit compares whether the number of times the correction image is shot is less than the preset number of times, and when the correction image is shot, the correction image is shot. When the number of shots is less than the preset number of shots, step S21 is executed. When the number of shots of the calibrated image is equal to the preset number of shots, step S31 is executed. (S31) The control unit calculates all stored offsets to obtain an average offset, 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 test station tests a lens to be tested, the control unit replaces the original center coordinate with the calibrated original center coordinate to perform the test at the lens test station.

In some embodiments, the original center coordinates are obtained by the control unit calculating the center points of the images generated by the plurality of calibration lenses when the lens testing station is initially established.

In some embodiments, the correction lens is a lens that has been inspected and assembled completely correctly.

In some embodiments, the storage medium further stores a preset warning count, and the lens test station calibration method further includes a periodic calibration step. The periodic calibration step includes: recording a cumulative test count of the lens test station via the control unit, and when the cumulative test count reaches the preset warning count, displaying a warning message on the user interface asking whether to agree to calibrate the lens test station, and waiting for a user input.

In some embodiments, the initial value of the accumulated test times is zero, and the control unit adds one to the accumulated test times when the lens test station completes a lens test.

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.

In some embodiments, the lens actuator assembly includes a first linear slide parallel to the upper surface of the base; a second linear slide connected to a slider of the first linear slide, with the track of the second linear slide perpendicular to the track of the first linear slide; a first turntable connected to the slider of the second linear slide, with the rotation axis of the first turntable perpendicular to the upper surface of the base; and a second turntable connected to the disk of the first turntable, with the rotation axis of the second turntable perpendicular to the rotation axis of the first turntable. The first linear slide, the second linear slide, the first turntable, and the second turntable are all driven by a servo motor to enable the lens mount to rotate in a specified direction as instructed.

In some embodiments, the target actuator assembly includes a third linear slide and a third turntable mounted on a slider of the third linear slide. The third linear slide and the third turntable are both driven by a servo motor to adjust the distance and relative angle between the test image and the lens mount.

As described above, the calibration method for a lens test station in this case uses the control unit to average the offset values obtained from multiple shots and write the average offset value to obtain the calibrated original center coordinates. The lens is then tested using these calibrated original center coordinates. This reduces calibration time, improves the accuracy and reliability of the calibrated lens test station, and enhances factory workflow efficiency.

100: Lens testing station

10: Base

20: Lens actuator assembly

21: First linear slide rail

22: Second linear slide rail

23: First turntable

24: Second turntable

30: Lens mount

40: Image capture unit

50: Target actuator assembly

51: Third linear slide rail

52: Third Turntable

60: Test image

60’: Image to be tested

70: Lens to be tested

72: Standard Image

73: Image Correction

72a,73a: Center coordinates

80: Control unit

S10, S11, S12, S12’, S13, S14: Steps

S20’, S20, S21, S22, S23, S31: Steps

S40, S41, S41’, S42, S43: Steps

To make the above and other objects, features, advantages and embodiments of the present invention more clearly understood, the present invention can be better understood by reading it in conjunction with the accompanying drawings.

The first picture shows the structure of Xizhi's lens testing station.

Figure 1A is a schematic diagram of the lens testing station of the present invention.

Figure 1B shows an image captured by the lens under test at the lens testing station of the present invention.

The second figure is a flow chart of the lens testing station in an embodiment of the present invention.

Figure 3 is a flow chart of calibrating a lens testing station in an embodiment of the present invention.

Figure 4A is a schematic diagram of an ideal image captured during calibration of a lens testing station in an embodiment of the present invention.

Figure 4B is a schematic diagram of an image captured during calibration of a lens testing station in an embodiment of the present invention.

Figure 5 is a flow chart for triggering periodic calibration of a lens testing station in an embodiment of the present invention.

To illustrate in detail the technical content, structural features, objectives, and effectiveness of the calibration method for the lens test station of the present invention, the following examples are given with accompanying drawings for detailed explanation. For ease of explanation, in this patent specification, "upper" is defined as a higher position in the direction facing the drawings, "lower" is defined as a lower position in the direction facing the drawings, "left" is defined as the left-hand side in the direction facing the drawings, and "right" is defined as the right-hand side in the direction facing the drawings.

Referring to FIG. 1A , the present invention discloses a calibration method for a lens test station. The lens test station 100 is configured to test a lens 70 to be inspected and comprises: a base 10, a lens actuator assembly 20 secured to the base 10, a lens mounting base 30 mounted on the lens actuator assembly 20, an image capture unit 40 mounted on the lens mounting base 30, a target actuator assembly 50 mounted on one side of the base 10, a test image 60 mounted on the target actuator assembly 50, and a control unit 80.

In this embodiment, the lens actuator assembly 20 includes a first linear rail 21 whose track is parallel to the upper surface of the base 10, a second linear rail 22 with a slider connected to the first linear rail 21, a first turntable 23 with a slider connected to the second linear rail 22, and a second turntable 24 connected to the disk surface of the first turntable 23. The track of the first linear rail 21 is perpendicular to the track of the second linear rail 22, and the first linear rail 21 is set to the left and right direction, while the track of the second linear rail 22 is set to the front and 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 21. The first linear slide 21, the second linear slide 22, the first turntable 23, and the second turntable 24 are all driven by a servo motor, thereby enabling the lens mount 30 to align in a specified direction as instructed.

The lens mount 30 is mounted on the lens actuator assembly 20 and, when driven by the lens actuator assembly 20, is aligned in a specified direction according to instructions and is used to secure the lens 70 to be inspected. In this embodiment, when the slider of the first linear rail 21 slides, the lens mount 30 moves left or right. When the slider of the second linear rail 22 moves, the lens mount 30 moves forward or backward. When the first turntable 23 rotates, the lens mount 30 moves upward or downward. When the second turntable 24 rotates, the lens mount 30 moves slightly left or right. The image capture unit 40 is mounted on the lens mount 30 and is located on the optical axis of the lens to be inspected 70 to capture images through the lens to be inspected 70.

The target actuator assembly 50 includes a third linear slide rail 51 and a third rotary plate 52 disposed on the slider of the third linear slide rail 51. The third linear rail 51 is oriented horizontally. The rails of the third linear rail 51, the rotating axis of the third turntable 52, and the rails of the first linear rail 21 are all parallel. Both the third linear rail 51 and the third turntable 52 are driven by servo motors. The slider of the third linear rail 51 moves the test image 60 away from or closer to the lens mount 30, and the rotation of the third turntable 52 slightly moves the test image 60 away from or closer to the lens mount 30, thereby adjusting the relative distance and angle between the test image 60 and the lens mount 30.

Referring again to FIG. 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 the servo motors in the lens actuator assembly 20 and the target actuator assembly 50. Furthermore, the control unit 80 is electrically connected to the image capture unit 40 to receive inspection images captured by the image capture unit 40 and calculate the assembly error of the lens 70 to be inspected.

Referring now to Figures 1A to 2, the testing method of the lens testing station 100 includes the following steps:

S10: The control unit 80 controls and drives the lens actuator assembly 20 and the target actuator assembly 50 to align the lens 70 to be tested with the test image 60.

S11: The image capture unit 40 and the test lens 70 capture the test image 60 to capture at least one test image 60' generated by the test lens 70 and transmit it to the control unit 80. The test image 60' is an image within the visual range of the test lens 70.

S12: After receiving the image to be inspected 60', the control unit 80 calculates the difference between the center coordinates of the image to be inspected 60' and an original center coordinate. The center coordinates of the image to be inspected 60' are the coordinates of the intersection of two black squares in the image to be inspected 60'. In this embodiment, the original center coordinates are calculated by the control unit 80 during the initial establishment of the lens testing station 100 by calculating the center points of images generated by multiple calibration lenses (not shown) fixed to the lens mount 30. The calibration lens is a lens that has been inspected and assembled correctly with virtually no errors.

S12': The control unit 80 determines whether the difference exceeds a threshold. In practice, the threshold is 22.6 pixels.

S13: If the difference exceeds 22.6 pixels, the control unit 80 determines that the lens 70 to be tested has failed the test.

S14: If the difference does not exceed 22.6 pixels, the control unit 80 determines that the lens 70 to be tested has passed the test.

As shown in FIG4A , since the calibration lens is a verified, correctly assembled, and nearly error-free lens, when the lens testing station 100 is correctly configured, a standard image 72 captured by the calibration lens contains no errors. In other words, the center coordinates of the standard image 72 completely coincide 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.

Referring again to Figures 1A and 3 to 4B, the calibration method for the lens testing station 100 of the present invention includes the following steps:

S20': The operator installs the correction lens (not shown) on the lens fixing base 30.

S20: The control unit 80 controls the lens actuator assembly 20 and the target actuator assembly 50 according to preset data, aligning the calibration lens with the test image 60 and returning the calibration image capture count to zero. The process then proceeds to step S21.

S21: The test image 60 is captured by the calibration lens and the image capture unit 40. The calibration image 73 is captured by the image capture unit 40 and transmitted to the control unit 80. Then, step S22 is executed.

S22: The control unit 80 calculates a center coordinate 73a of the corrected image 73 and an offset of the center coordinate 73a from the original center coordinate 72a. The control unit 80 then stores the offset in a storage medium accessible to the control unit 80. The control unit 80 then adds one to the number of times the corrected image was captured and executes step S23.

S23: The control unit 80 compares the number of calibration image captures to see if it is less than a preset number. If so, step S21 is executed; if so, step S31 is executed. The calibration image capture number is the number of times the image capture unit 40 captures the test image 60 using the calibration lens. In practice, the preset number of captures is set to 15.

As shown in Figures 4A and 4B, in the standard image 72 obtained when the lens test station 100 is correctly configured, the center coordinate 72a of the standard image 72 is nearly completely aligned with the center coordinate of the image to be inspected 60'. This means that there is almost no offset between the original center coordinate and the center coordinate of the image to be inspected 60'. However, when the lens test station 100 is used for a long period of time, the lens actuator assembly 20 may experience operational errors, and the lens mount 30 may wear out. This indicates that there is an error in the configuration of the lens test station 100, causing the center coordinate 73a of the calibrated image 73 to deviate from the center coordinate 72a of the standard image 72. This means that there is an offset between the original center coordinate and the center coordinate 73a of the calibrated image 73.

S31: The control unit 80 calculates the average of all stored offsets, then adds the average offset to the original center coordinate to obtain a corrected original center coordinate, which is stored in the storage medium. Next, when the lens testing station 100 retests the lens 70 to be tested, the control unit 80 uses the corrected original center coordinate as an indicator to determine whether the lens 70 to be tested has passed the test.

Compared to conventional calibration methods, the calibration method disclosed herein does not require calculating the errors of each servo motor individually, nor does it require adjusting the drive parameters of each servo motor. Instead, the final error value of the lens actuator assembly and the target actuator assembly is directly calculated, and then the coordinate data of the original center is directly modified using software correction. Therefore, it is much faster than conventional calibration methods.

Referring again to Figures 1A and 5, the calibration method of the present invention further includes a periodic calibration step to maintain the correct configuration of the lens testing station 100. The periodic calibration step includes:

S40: The control unit 80 records a cumulative test count of the lens test station 100. The control unit 80 increments the cumulative test count by one when the lens test station 100 completes a lens test on the lens 70 to be tested. The initial value of the cumulative test count is zero. In practice, the cumulative test count increments by one when the lens test station 100 completes a test. This completes a single cycle of steps S10 to S14, with the cumulative test count incrementing by one.

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. The warning message asks the operator whether to calibrate the lens test station 100 and waits for the operator's response. In practice, the default warning number is set to 500 based on actual factory operations.

S41': When the control unit 80 receives user input indicating that the lens test station 100 agrees to be calibrated, step S42 is executed. When the control unit 80 receives user input indicating that the lens test station 100 disagrees to be calibrated, step S43 is executed.

S42: Calibrate the lens test station 100 and reset the accumulated test count of the lens test station 100 to zero. In practice, if the user determines that the lens test performed by the lens test station 100 is temporarily terminated and clicks "Agree," calibration of the lens test station 100 will begin.

S43: The lens testing station 100 continues testing the lens 70 to be tested. In practice, the user may be unable to interrupt or terminate the test because the lens testing station 100 is still in progress. Therefore, if the user clicks "Disagree," the lens testing station 100 will continue testing the lens 70 to be tested.

The control unit 80 may be, but is not limited to, a desktop computer or laptop computer with a screen and keyboard, or any other component or device suitable for a display interface that can receive user input and perform data access, data calculation, data storage, or similar functions.

In summary, compared to conventional techniques, the lens test station 100 calibration method of the present invention uses the calibrated original center coordinates as the criterion for determining whether the lens 70 under test has passed the test. This method can reduce calibration time and improve the accuracy and reliability of the calibrated lens test station 100, thereby enhancing the efficiency of factory operations.

Although this application has been disclosed above through embodiments, they are not intended to limit this application. Anyone with ordinary skill in the art may make minor modifications and improvements without departing from the spirit and scope of this application. Therefore, the scope of protection of this application shall be determined by the scope of the attached patent application.

S20’, S20, S21, S22, S23, S31: Steps

Claims (8)

A calibration method for a lens test station, the lens test station comprising: a base; a control unit having a storage medium and a user interface, the storage medium storing a preset number of shots and an original center coordinate; a lens actuator assembly fixed to the base and electrically connected to the control unit; a target actuator assembly disposed on a side of the base and electrically connected to the control unit, the target actuator assembly being provided with a test image; a lens mounting base disposed on the lens actuator assembly; and an image capture unit disposed on the lens mounting base and electrically connected to the control unit, and located on an optical axis of a calibration lens to capture an image through the calibration lens. The calibration method for the lens test station includes the following steps: (S20) The control unit controls the lens actuator assembly and the target actuator assembly according to preset data, aligning the calibration lens with the test image and resetting the calibration image capture count to zero, followed by step S21; (S21) The calibration lens and the image capture unit capture the test image, the image capture unit captures the calibration image, and transmits it to the control unit, followed by step S22; (S22) The control unit calculates a center coordinate of the corrected image and an offset of the center coordinate relative to the original center coordinate, and stores the offset in the storage medium. The control unit then adds one to the number of times the corrected image was captured and executes step S23. (S23) The control unit compares whether the number of times the corrected image was captured is less than the preset number of times. If the number of times the corrected image was captured is less than the preset number of times, step S21 is executed. If the number of times the corrected image was captured is equal to the preset number of times, step S31 is executed. (S31) The control unit calculates all stored offsets to obtain an average offset, 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 tests a lens to be tested, the control unit replaces the original center coordinate with the corrected original center coordinate to perform the lens test station test. A calibration method for a lens test station as described in claim 1, wherein the original center coordinates are obtained by the control unit calculating the center points of multiple standard images generated by the calibration lenses when the lens test station is initially established. A calibration method for a lens testing station as described in claim 1, wherein the calibration lens is a lens that has been inspected and assembled completely correctly. A method for calibrating a lens test station as described in claim 1, wherein the storage medium further stores a preset warning number, and the method for calibrating the lens test station further includes a periodic calibration step, wherein the periodic calibration step includes: recording a cumulative number of tests of the lens test station via the control unit, and when the cumulative number of tests reaches the preset warning number, displaying a warning message on the user interface asking whether the user agrees to calibrate the lens test station, and waiting for a user input. A calibration method for a lens test station as described in claim 4, wherein the initial value of the accumulated test times is zero, and the control unit adds one to the accumulated test times when the lens test station completely runs a lens test. A method for calibrating a lens test station as described in claim 4, wherein when the control unit receives the user input agreeing to calibrate the lens test station, the lens test station is calibrated and the accumulated test times of the lens test station are reset to zero. The lens test station calibration method of claim 1, wherein the lens actuator assembly comprises: a first linear slide parallel to the upper surface of the base; a second linear slide connected to a slider of the first linear slide, the track of the second linear slide being perpendicular to the track of the first linear slide; a first turntable connected to the slider of the second linear slide, the rotation axis of the first turntable being perpendicular to the upper surface of the base; and a second turntable connected to the disk surface of the first turntable, the rotation axis of the second turntable being perpendicular to the rotation axis of the first turntable. The first linear slide rail, the second linear slide rail, the first turntable, and the second turntable are all driven by a servo motor, so that the lens mount can rotate in a specified direction as instructed. A calibration method for a lens test station as described in claim 7, wherein the target actuator assembly includes a third linear slide and a third turntable with a slider disposed on the third linear slide, and the third linear slide and the third turntable are both driven by a servo motor to adjust the distance and relative angle between the test image and the lens fixing base.