CN112834173A

CN112834173A - Focal length correction method for vehicle lens module

Info

Publication number: CN112834173A
Application number: CN201911153713.0A
Authority: CN
Inventors: 黄铭嘉; 杨容玮
Original assignee: Fuhong Shanghai Electronic Technology Co Ltd; Yaohong Jiaxing Electronic Technology Co ltd; MKD Tech Inc
Current assignee: Fuhong Shanghai Electronic Technology Co Ltd; Yaohong Jiaxing Electronic Technology Co ltd; MKD Tech Inc
Priority date: 2019-11-22
Filing date: 2019-11-22
Publication date: 2021-05-25

Abstract

The invention relates to a method for correcting the focal length of a vehicle lens module, which is applied to an optical test environment and comprises a lens module, a jig, a test chart and a test device. The method can reduce the influence of artificial factors in the traditional correction process, improve the efficiency of lens focal length correction, reduce errors and improve the accuracy.

Description

Focal length correction method for vehicle lens module

Technical Field

The invention relates to a focal length correction method of a vehicle lens module, in particular to a correction method for adjusting a definition value by calculating a test chart and an interested area.

Background

The specifications of portable electronic products are changing day by day, and the optical imaging lens, a key part of the portable electronic products, is also more diversified and developed. The application field of the lens for the vehicle is continuously increasing along with the improvement of science and technology. For example, the fields of backing, 360-degree surround scenes, lane departure Systems, Advanced Driver Assistance Systems (ADAS), and the like all require the use of a vehicular lens.

Driving safety is important for the driver and the passenger. There are many techniques to use the images captured by the lens to assist driving safety. For example, when backing a car, the rear camera can be used to capture the rear image, and the driver can also judge whether there are obstacles, pedestrians, etc. behind the car by using the rear image captured by the rear safety auxiliary system besides visual observation.

These vehicle safety support systems (e.g., full-circle surveillance systems, forward collision avoidance warning systems, rear safety support systems, side blind spot warning systems, etc.) generally include a vehicle lens for capturing images of the exterior of the vehicle. Therefore, the lens for a vehicle mounted on the vehicle must be corrected before shipment.

At present, the traditional man-machine calibration method for the vehicle lens needs to rely on calibration personnel to perform manual fine tuning, so that the characteristic image in the image can meet the preset condition, and the image can be adjusted to the correct position through man-machine operation. However, the conventional calibration process often results in image errors due to human error due to different observation and care of testers. A more accurate correction method is therefore required.

Disclosure of Invention

In view of the above problems, the present invention is directed to a method for correcting a focal length of a vehicular lens module, which reduces the influence of artifacts in a conventional correction process.

The present invention relates to a lens module for a vehicle, and more particularly to a lens module for a vehicle, which is a non-floating lens, and is limited to a rotational adjustment structure.

Preferably, the method for correcting the focal length of the vehicular lens module is applied to an optical test environment, wherein the optical test environment can be an open environment or comprises a lamp box, and comprises the lens module, a jig, a test graphic card and a test device, wherein the test graphic card is provided with a specific graph, the test device is a device with a display interface, and the lens module is electrically connected with the test device.

Preferably, the testing device comprises an operation module, wherein the operation module mainly calculates a region of interest (ROI) and a sharpness value of the lens module.

The method for correcting the focal length of the lens module for the vehicle requires an operator to manually adjust the lens of the lens module, simultaneously watches whether the picture of the display interface of the testing device is clear or not, and is matched with the definition value calculated by the testing device, and when the lens is adjusted and the definition value reaches the maximum value, the focal length correction of the lens module is finished.

According to the invention, the labor cost and the time cost brought by the traditional vehicle lens correction are improved, and the errors caused by the change of the test graphic card graph viewed by human eyes are improved, and the calculation of the definition value in the region of interest in the test device is replaced, so that the efficiency of lens focal length correction is improved, the errors are reduced, and the accuracy is improved.

Drawings

FIG. 1 is a schematic view of a lens module capable of adjusting a focal length by rotation according to the present invention;

FIG. 2 is a schematic diagram of an embodiment of the present invention;

FIG. 3 is a schematic view of another embodiment of the present invention;

FIG. 4 is a flowchart illustrating a method for correcting a focal length of a lens module for a vehicle according to the present invention;

FIG. 5 is a schematic view of a display interface of the testing apparatus of the present invention.

10 lens module

11 lens

12 lens carrier

13 infrared filter

14 light sensor

15 printed circuit board

16 screw thread

20 jig

30 test chart

40 testing device

41 region of interest

Detailed Description

The embodiments of the present invention will be described in more detail with reference to the drawings and the accompanying reference numerals, which will enable those skilled in the art to practice the invention after reading the specification.

The invention is a focal length correction method of the lens module for vehicle, wherein, the lens module for vehicle needs the non-floating lens, namely define the wide-angle lens module or flat lens module of vehicle in the rotary adjustment structure, and the lens module adopts the passive focusing, in order to guarantee the vehicle can still focus when the backlight or through the glass, as shown in fig. 1, display the basic lens module schematic diagram of the rotary adjustment focal length, the lens module 10 includes the lens 11, the lens carrier 12, the infrared ray filter 13, the light sensor 14, the printed circuit board 15 and whorl 16.

Further, the lens 11 is rotatably fixed to the lens carrier 12 through a screw 16 on the lens carrier 12 while maintaining an adjustment space, and the focal length of the lens module 10 is adjusted by manually rotating the lens 11.

It should be noted that, instead of manually rotating the lens 11 to adjust the focal length of the lens module 10, the present invention may also design a special mechanical device.

In addition, an embodiment of the method for calibrating the focal length of the vehicular lens module according to the present invention is applied to the optical testing environment shown in fig. 2, and includes a lens module 10, a fixture 20, a test card 30 and a testing device 40, wherein the lens module 10 is disposed on the fixture 20, the lens module 10 is electrically connected to the testing device 40, the fixture 20 includes a carrier and a fixing element, the test card 30 is fixed on the carrier, so that the distance between the test card 30 and the lens module 10 is kept fixed, and the fixing element is used for fixing the lens module 10.

The lens module 10, the fixture 20 and the test card 30 are specifically disposed in a lamp box in an optical test environment, and among the relevant parameters in the lamp box, the illumination is 200 to 1500Lux, the color temperature is 5000 to 7000K, preferably, the illumination is 500 to 1000Lux, and the color temperature is 5500 to 6500K.

It should be noted that the lens module 10 is electrically connected to the testing device 40 through an RCA socket at the input end and a USB plug at the output end, and the image collected by the lens module 10 is input into the RCA card and converted into a USB to be output to the testing device 40.

In addition, the normal of the lens module 10 is perpendicular to the test card 30 fixed on the carrier.

The testing device 40 is a computer including an operation module, which mainly calculates a region of interest (ROI) and a sharpness value of the lens module 10, wherein the ROI is a region of interest set to focus on or simplify a working process in an image processing field, that is, a region of an image is selected from the image, and the region is a focus of image analysis.

Specifically, the operation module of the testing device 40 performs edge detection on the image collected in the region of interest by using an algorithm to form a determination image, and calculates a generated sharpness value according to the determination image to be used as a basis for focus correction.

Referring to fig. 3, in another embodiment of the present invention, in this embodiment, the lens module 10 is installed and fixed on a fixture 20 in an optical test environment, and the test card 30 is disposed on a corresponding wall, and similarly, the normal lines of the test card 30 and the lens module 10 are perpendicular to each other, and the illumination is 200 to 1500Lux, the color temperature is 5000 to 7000K, preferably 500 to 1000Lux, the color temperature is 5500 to 6500K, and the other configurations and connection manners are the same in the optical test environment.

Referring to fig. 4, the method for calibrating the focal length of the vehicular lens module according to the present invention firstly fixes the lens module 10 in an optical testing environment (e.g. on a fixture 20 in the optical testing environment), which is very common but important, because the subsequent step of synchronously adjusting the focal length of the lens module 10 is required to ensure that the position of the lens module 10 does not move.

Then, the lens module 10 is electrically connected to the testing device 40, so that the image collected by the lens module 10 can be transmitted to the testing device 40 and displayed on the display interface of the testing device 40.

After connecting and confirming the lens module 10 and the testing device 40, the test card 30 is fixed on the carrier, it should be noted that the distance between the test card 30 and the lens module is fixed, and it is confirmed on the display interface of the testing device 40 that the pattern in the test card 30 is located in the region of interest of the lens module 10.

The frame displayed on the display interface of the testing device 40 can refer to fig. 5, fig. 5 is only one embodiment, and the display mode of the display screen is not limited, a frame can be seen in the display interface, the frame is a region of interest (ROI)41, the region of interest 41 needs to be adjusted to a graph aligned in the test chart card 30, the testing device 40 is used to adjust the range size of the region of interest 41 to make the region of interest conform to the graph in the test chart card 30, and a sharpness value and a maximum value (MAX) are displayed on the upper left of the display interface, wherein the maximum value of the lens focal length sharpness value is calculated by a program, and the sharpness value is a value in actual detection, and the value is changed by adjusting the lens focal length.

After the lens module 10, the test card 30 and the test device 40 are ready, the operator starts to manually adjust the lens 11 of the lens module 10, and simultaneously watches whether the display interface of the test device 40 is clear, and matches the sharpness value calculated by the test device 40, and when the sharpness value is the same as the maximum value, the focus calibration of the lens module 10 is completed.

It should be noted that each of the lens modules 10 manufactured by the factory cannot be precisely adjusted to the predetermined maximum value during the calibration, so that the maximum value of the sharpness value is not necessarily the same as the predetermined maximum value when the focal length of the lens module 10 is manually adjusted, but the maximum value of the sharpness value is still used as the basis for completing the calibration when the sharpness value reaches the maximum value during the calibration.

Therefore, after the calibration is completed, the maximum sharpness values of all the lens modules 10 form a distribution curve, and the lens modules 10 exceeding a certain maximum sharpness value are determined to pass according to the requirement of the user on the yield, and conversely, the lens modules 10 below the certain maximum sharpness value are eliminated.

The invention has the main effects of improving the error caused by the change of the test graphic card observed by naked eyes when the traditional vehicle lens is corrected, and improving the speed of correcting the focal length of the lens, reducing the error and improving the accuracy by calculating the definition value in the region of interest in the testing device instead.

The invention has another effect that the working efficiency of the personnel is relatively improved because the occurrence of overuse of eyes of the personnel is reduced.

The foregoing is illustrative of the preferred embodiments of the present invention and is not to be construed as limiting thereof in any way, and therefore, any modification or variation of the present invention without departing from the spirit thereof is intended to be covered thereby.

Claims

1. A method for correcting focal length of a vehicular lens module is applied to a spiral focusing lens, and comprises the following steps:

fixing a lens module in an optical test environment, wherein the illumination of the optical test environment is 200-1500 Lux, and the color temperature is 5000-7000K;

electrically connecting the lens module with a testing device, and transmitting the image captured by the lens module to a display interface of the testing device for display;

fixing a test graphic card on a carrier in the optical test environment, wherein a display interface of the test device displays an image which is acquired by the lens module and contains the test graphic card;

adjusting the size of an interested area range displayed on a display interface of the test device to enable the image of the test graphic card to be positioned in the interested area range;

rotating the lens of the lens module to adjust the focal length and observing the change of a definition degree value displayed on the display interface of the testing device; and when the definition value reaches the maximum value, finishing the focal length correction of the lens module.

2. The method of claim 1, wherein the optical testing environment comprises a fixture, and the carrier is disposed on one of the sides of the fixture.

3. The method of claim 2, wherein the fixture comprises a fixing element for fixing the lens module and keeping the distance between the lens module and the test card consistent.

4. The method of claim 1, wherein the test card is fixed to the carrier and perpendicular to a normal of the lens module.

5. The method for adjusting focal length of a vehicular lens module according to claim 1, wherein the lens module is selected from one of a helical wide-angle lens and a helical flat lens, and the non-floating lens requires manual rotation to adjust the focal length.

6. The method for focal length correction of a vehicular lens module according to claim 1, wherein the lens module belongs to passive focusing.

7. The method for calibrating a focal length of a vehicular lens module according to claim 1, wherein the testing device comprises an operation module for performing an edge detection on the image in the region of interest and forming a determination image.

8. The method of claim 7, wherein the computing module calculates the sharpness value according to the determination image.

9. The method for calibrating a focal length of a vehicular lens module according to claim 1, wherein the lens module is electrically connected to the testing device through a transfer card, the input terminal of the transfer card is an RCA socket, and the output terminal thereof is a USB plug.

10. The method for focal length calibration of a vehicular lens module as claimed in claim 1, wherein after all the lens modules are calibrated, the maximum sharpness values of all the lens modules are counted to form a distribution graph.