CN117270229A - Method and device for active alignment of camera module - Google Patents

Method and device for active alignment of camera module Download PDF

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Publication number
CN117270229A
CN117270229A CN202311142576.7A CN202311142576A CN117270229A CN 117270229 A CN117270229 A CN 117270229A CN 202311142576 A CN202311142576 A CN 202311142576A CN 117270229 A CN117270229 A CN 117270229A
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China
Prior art keywords
lens
roi
image
camera module
axis
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CN202311142576.7A
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Chinese (zh)
Inventor
蔡正根
叶威铅
王庆春
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Shanghai Yanding Information Technology Co ltd
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Shanghai Yanding Information Technology Co ltd
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Priority to CN202311142576.7A priority Critical patent/CN117270229A/en
Publication of CN117270229A publication Critical patent/CN117270229A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B23P19/10—Aligning parts to be fitted together
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/62—Optical apparatus specially adapted for adjusting optical elements during the assembly of optical systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
    • G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B13/00—Viewfinders; Focusing aids for cameras; Means for focusing for cameras; Autofocus systems for cameras
    • G03B13/32—Means for focusing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B17/00—Details of cameras or camera bodies; Accessories therefor
    • G03B17/02—Bodies

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Studio Devices (AREA)

Abstract

The application provides a method and a device for actively aligning a camera module, wherein the method comprises the following steps: aligning an optical axis of a lens of the camera module with the center of the image sensor; the lens is controlled to move from a starting position to a final position at a constant speed in a movable range, the image card is photographed at different positions, a plurality of images are obtained, and the z-axis height value of the lens is synchronously obtained; determining a central ROI region of each image and at least two ROI regions outside the central ROI region, respectively calculating SFR values of the ROI regions of each image, and obtaining defocus curves of the ROI regions based on the SFR values and the z-axis height values of the corresponding lenses; obtaining the inclination angle of the lens based on the defocus curves of at least three ROI areas; and if the inclination angle meets a preset threshold value, determining a z-axis height value of the lens based on the defocus curves of all the ROI areas. The method can synchronously complete the shooting of the image card and the acquisition of the z-axis position of the lens in the uniform movement process, shortens the active alignment time and improves the production efficiency.

Description

Method and device for active alignment of camera module
Technical Field
The application relates to the technical field of electronic equipment manufacturing, in particular to a technology for actively aligning a camera module.
Background
Along with the high-speed development of mobile internet, internet of things and autopilot technology, requirements of intelligent terminal equipment, autopilot vehicles, intelligent manufacturing factories and the like on camera modules are rapidly improved, and requirements on higher accuracy are provided for definition and consistency of the camera modules. For example, the front view camera module of the automatic driving vehicle is used for shooting road conditions in front of the vehicle, is also used for ranging, anti-collision and the like, has long focal length, and also provides higher requirements on the assembly performance of the camera module.
The AA (Active Alignment) technology is a fine automatic assembly technology commonly used in a camera module production line, and can automatically align a lens of a camera module with an image sensor, so that the center of the lens and the center of the image sensor are located on the same axis perpendicular to a focal plane as much as possible, and the image sensor is located on the focal plane of the lens and parallel to the focal plane. The definition and optical axis alignment precision of the camera module can be greatly improved by using the AA technology, and the inclination degree of a focal plane is reduced, so that the image acquisition quality and consistency of the camera module can be improved, and the imaging image quality of the camera module assembled by using the AA technology is closest to the best.
In the prior art AA, the z-axis position of a lens is usually adjusted step by step along the direction of an optical axis (z-axis), the z-axis position of the lens at the present time is recorded each time, a photo is taken on a test chart (or called an image detection board) after the lens is adjusted to be stable in place, then the image quality indexes of relevant ROI areas in the photo are calculated and compared according to all the obtained photos, the z-axis positions of the lens corresponding to the best image quality indexes of different ROI areas are determined, the distance difference value of the z-axis positions of the relevant lens is determined, and tilt correction is performed according to the distance difference value. Optical centering is also performed according to the deviation of the center position of the photo center region from the center of the image sensor in the x/y plane (i.e., the deviation in the x/y axis direction of the plane).
In the prior art AA, the adjustment of the z-axis position of the lens of the camera module is usually realized through a motor driving transmission mechanism and clamping jaws, the motor is required to start and stop in place after each adjustment, the photo is shot after the lens of the camera module is stable, the motor is required to repeatedly start and stop in the whole process and the motor is required to be stable, so that more time is spent on active alignment of the camera module on a production line, and the production efficiency is affected.
Disclosure of Invention
The purpose of the application is to provide a method and a device for actively aligning a camera module, which are used for at least partially solving the technical problem of insufficient production efficiency caused by repeated starting and stopping of a motor and waiting for the motor to be stable in the prior AA technology.
According to one aspect of the present application, there is provided a method for active alignment of a camera module, wherein the method comprises:
aligning an optical axis of a lens of a camera module with a center of an image sensor of the camera module;
the lens is controlled to move at a constant speed from a starting position to a final position in a movable range, in the process of moving the lens at a constant speed, a plurality of images are obtained through the image sensor by photographing the image card at different positions, wherein the center of the image card is aligned with the center of the image sensor, and when the images are obtained, the z-axis height value of the lens is synchronously obtained;
determining a center ROI (region of interest) of each image and at least two ROI (region of interest) outside the center ROI, calculating SFR (small form factor) values of the at least three ROI of each image according to patterns in the at least three ROI, and obtaining a defocusing curve of the at least three ROI based on the SFR values of the at least three ROI of each image and a z-axis height value of a lens corresponding to the image;
obtaining the inclination angle of the lens based on the defocus curves of the at least three ROI areas;
and judging whether the inclination angle meets a preset threshold value, if so, determining a z-axis height value of the lens based on the defocusing curves of the at least three ROI areas so as to finish the active alignment of the camera module.
Optionally, the aligning the optical axis of the lens of the camera module with the center of the image sensor of the camera module includes:
photographing the image card at any position in the movable range of the lens of the camera module, and obtaining an image through the image sensor;
determining a center point of a pattern in a center ROI area of the image, and calculating a deviation of the center point from the center of the image;
and carrying out x-axis and/or y-axis compensation on the camera module based on the deviation so as to finish the alignment of the optical axis of the lens and the center of the image sensor.
Optionally, the photographing the graphics card at different positions includes:
the cards were photographed at random at different locations.
Optionally, the photographing the graphics card at different positions includes:
and photographing the graphic card at the multiple position of the preset step length.
Optionally, the obtaining the tilt angle of the lens based on the defocus curves of the at least three ROI areas includes:
determining a z-axis height value corresponding to a peak point of the defocus curve of each ROI region and an x/y-axis coordinate value of a feature point of the pattern in the corresponding ROI region based on the defocus curves of the at least three ROI regions;
and carrying out plane fitting according to the z-axis height value corresponding to the peak point of the defocusing curve of each ROI region and the x/y-axis coordinate value of the characteristic point of the pattern in the corresponding ROI region to obtain a fitting plane, and determining the included angle between the fitting plane and the plane of the image sensor of the camera module as the inclination angle of the lens.
Optionally, the performing plane fitting according to the z-axis height value corresponding to the peak point of the defocus curve of each ROI area and the x/y-axis coordinate value of the feature point of the pattern in the corresponding ROI area includes:
determining a space feature point corresponding to each ROI region according to a z-axis height value corresponding to a peak point of the defocus curve of each ROI region and an x/y coordinate value of a feature point of the pattern in the corresponding ROI region;
and performing plane fitting according to the spatial feature points corresponding to each ROI region.
Optionally, the feature points of the pattern in the ROI area include any one of the following:
centroid of pattern in ROI area;
center point of the pattern in the ROI area.
Optionally, wherein the determining the z-axis height value of the lens based on the defocus curves of the at least three ROI areas comprises:
determining a z-axis height value corresponding to a peak point of the defocus curves of each ROI region based on the defocus curves of the at least three ROI regions;
and adding a weight to the z-axis height value corresponding to the peak point of the defocusing curve of each ROI region, calculating a weighted average value, and determining the weighted average value as the z-axis height value of the lens.
Optionally, if the tilt angle does not meet a preset threshold, the method for actively aligning the camera module further includes:
and performing tilt angle compensation on the lens based on the deviation degree of the tilt angle, controlling the lens to reset to the initial position, repeating the steps until the obtained tilt angle meets a preset threshold, and determining the z-axis height value of the lens based on the defocusing curves of at least three ROI areas obtained currently so as to finish the active alignment of the camera module.
Optionally, an apparatus for performing the method for active alignment of a camera module is provided, wherein the apparatus includes:
the machine comprises a machine table, a jig, clamping jaws, a motor, a transmission mechanism, an image acquisition card and an upper computer, wherein,
the jig is fixed on the machine table and used for fixing the camera module;
one end of the clamping jaw clamps the lens of the camera module, the other end of the clamping jaw is horizontally and fixedly connected with the transmission mechanism, the transmission mechanism is driven by the motor to drive the clamping jaw to vertically move along the z-axis, and the clamping jaw is controlled to drive the lens to horizontally move and/or rotate along the x/y-axis, wherein the coded data of the encoder of the motor corresponds to the z-axis height value of the lens one by one;
the image acquisition card is integrated in the upper computer and is respectively and electrically connected with the image sensor of the camera module and the motor, when the camera module is controlled to shoot the image card, an image acquired by the image sensor is acquired, and coding data of an encoder of the motor is acquired so as to synchronously acquire the z-axis height value of the lens;
the upper computer is used for controlling the image acquisition card to acquire an image and a z-axis height value of the lens corresponding to the image, calculating optical center deviation with the center of the image according to a center point of a pattern in a center ROI (region of interest) of the image, obtaining a defocusing curve of at least three ROI regions according to the calculated center ROI of the image and SFR (small form factor) values of at least two ROI regions outside the center ROI, determining an inclination angle between the lens and the image sensor, determining a final positioning z-axis height value of the lens, outputting a signal, driving the transmission mechanism through the motor, controlling the clamping jaw to drive the lens to horizontally move along an x/y axis so as to compensate the optical center deviation, controlling the clamping jaw to drive the lens to rotate so as to compensate the inclination angle, and controlling the clamping jaw to vertically move to a position corresponding to the final positioning z-axis height value of the lens.
Compared with the prior art, the application provides a method and a device for actively aligning a camera module, wherein the method comprises the following steps: aligning an optical axis of a lens of a camera module with a center of an image sensor of the camera module; the lens is controlled to move at a constant speed from a starting position to a final position in a movable range, in the process of moving the lens at a constant speed, a plurality of images are obtained through the image sensor by photographing the image card at different positions, wherein the center of the image card is aligned with the center of the image sensor, and when the images are obtained, the z-axis height value of the lens is synchronously obtained; determining a center ROI (region of interest) of each image and at least two ROI (region of interest) outside the center ROI, calculating SFR (small form factor) values of the at least three ROI of each image according to patterns in the at least three ROI, and obtaining a defocusing curve of the at least three ROI based on the SFR values of the at least three ROI of each image and a z-axis height value of a lens corresponding to the image; obtaining the inclination angle of the lens based on the defocus curves of the at least three ROI areas; and judging whether the inclination angle meets a preset threshold value, if so, determining a z-axis height value of the lens based on the defocusing curves of the at least three ROI areas so as to finish the active alignment of the camera module. By the method, shooting of the image card and acquisition of the z-axis position of the lens can be synchronously completed in the uniform-speed moving process of the lens of the camera module, so that the active alignment time of the camera module is shortened, and the production efficiency of the camera module is improved.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:
FIG. 1 illustrates a flow chart of a method for active alignment of camera modules in accordance with an aspect of the subject application;
FIG. 2 illustrates a schematic diagram of an apparatus for active alignment of camera modules in accordance with another aspect of the present application;
the same or similar reference numbers in the drawings refer to the same or similar parts. For simplicity of the drawing, the figures schematically show portions relevant to the present invention and do not represent the actual structure thereof as a product.
In addition, for simplicity and ease of understanding in the drawings, components having the same structure or function in some drawings may be only schematically indicated at one of them.
Detailed Description
The camera module mainly comprises a lens, an image sensor, an optical filter, a circuit board and the like. The working principle is as follows: after light reflected by the surface of a shooting target passes through the lens and the optical filter, the light is captured by the image sensor, the captured light signal can be converted into an analog electric signal by the image sensor, and the analog electric signal is converted into a digital signal by an analog-to-digital conversion circuit in the circuit board. Wherein the quality of the imaged image obtained in this case is optimal if the lens center and the image sensor center are located on the same axis perpendicular to the focal plane and the image sensor is located on the focal plane of the lens.
For the camera module, focusing can be performed under specified object distance according to product focusing requirements, a focal plane of the camera module can be determined, then defocusing test is performed within a certain range above and below the relative position of the focal plane, and the lens and/or the image sensor of the camera module are subjected to x/y/z axis position adjustment according to a defocusing test curve, so that the process is alignment. Because the camera module assembly is a process of sequentially stacking and assembling a plurality of parts, there is a stacking tolerance, some parts are assembled, and there is a tolerance, for example, when a lens manufacturer assembles a lens, the optical axis of the lens may be shifted when the lens is stacked, and the lens is not absolutely positioned on the central axis of the lens, so that an AA process is required to achieve the best assembly effect when manufacturing, producing and assembling. In the active alignment process, the AA processing device adjusts the position of the x/y/z axis of the lens and/or the image sensor of the camera module by controlling the AA processing device (generally comprising a machine table, a jig, a motor, a transmission mechanism, a clamping jaw, an image acquisition card, an upper computer and the like) according to the result of performing quality evaluation processing on the actual imaging image corresponding to the image card shot by the camera module, so that the alignment of the lens and/or the image sensor of the camera module is realized.
In this application, a graphics card is used that includes at least five patterns (typically, a square or circle, but also a shaped pattern including straight or curved edges) at the center and four corners (typically, in the 0.7 field of view region). For the long-focus camera module, a collimator with a plane view card (the field angle of the collimator is usually not less than 30 degrees) can be used for replacing the graph card, or a range extender is added; for the large wide-angle camera module, at least five parallel light pipes with plane view cards can be used for replacing the image card, wherein one of the centers can use the parallel light pipe, and a combination of the distance-increasing mirror and the image card can be used, wherein the image card can only have one pattern at the center, and the parallel light pipes are adjusted according to the size of the view angle of the camera module, so that the pattern after photographing falls in a designated area of the image sensor/photo.
In order to further describe the technical means and effects adopted by the present application, the following description will be made in detail and complete with reference to the accompanying drawings and preferred embodiments.
Fig. 1 shows a flowchart of a method for active alignment of a camera module according to an aspect of the present application, where the method of the embodiment includes:
s101, aligning an optical axis of a lens of a camera module with the center of an image sensor of the camera module;
s102, controlling the lens to move at a constant speed from a starting position to a final position in a movable range, photographing a picture card at different positions in the constant-speed moving process of the lens, and obtaining a plurality of images through the image sensor, wherein the center of the picture card is aligned with the center of the image sensor, and synchronously obtaining the z-axis height value of the lens when the images are obtained;
s103, determining a center ROI (region of interest) of each image and at least two ROI areas outside the center ROI area, calculating SFR (small form factor) values of the at least three ROI areas of each image according to patterns in the at least three ROI areas, and obtaining defocusing curves of the at least three ROI areas based on the SFR values of the at least three ROI areas of each image and z-axis height values of lenses corresponding to the images;
s104, obtaining the inclination angle of the lens based on the defocus curves of the at least three ROI areas;
s105, judging whether the inclination angle meets a preset threshold value, if so, determining a z-axis height value of the lens based on the defocus curves of the at least three ROI areas so as to finish active alignment of the camera module.
The active alignment of the camera module includes an Optical Center (Optical Center) adjustment and a tilt angle (tilt) adjustment, which can be performed by the AA processing apparatus 100 during the AA process. In this embodiment, in step S101, the AA process apparatus 100 aligns the optical axis of the lens of the camera module with the center of the image sensor of the camera module.
The AA processing apparatus 100 captures an image of the image card through the camera module, determines a center point position of the center pattern, calculates an x/y axial deviation between the center point position and the center of the image (i.e., the center of the image sensor of the camera module), and performs x/y axis motion compensation to achieve alignment of the optical axis of the lens of the camera module and the center of the image sensor of the camera module, i.e., optical center alignment.
Optionally, the step S101 includes:
photographing the image card at any position in the movable range of the lens of the camera module, and obtaining an image through the image sensor;
determining a center point of a pattern in a center ROI area of the image, and calculating a deviation of the center point from the center of the image;
and carrying out x-axis and/or y-axis compensation on the camera module based on the deviation so as to finish the alignment of the optical axis of the lens and the center of the image sensor.
When the AA processing device 100 controls the lens to move in any position in the movable range, an image is photographed by an image sensor of the camera module, an image is obtained, wherein the image at least comprises a center ROI area, a center point position of a pattern in the center ROI area is determined, then an x/y axial deviation between the center point and the center of the image is calculated, wherein the center of the image is the center of the image sensor, then x-axis and/or y-axis compensation is performed on the camera module according to the deviation, the lens of the camera module can be moved in the x-axis and/or y-axis directions, and the image sensor of the camera module can be moved in the x-axis and/or y-axis directions, so that the optical center alignment of the camera module, namely the optical axis of the lens is aligned with the center of the image sensor, is completed.
The active alignment of the camera module needs to be out of focus adjustment besides the alignment of the optical center so as to adjust the inclination angle. In this embodiment, in step S102, the AA processing apparatus 100 controls the lens of the camera module to move from the starting position to the final position at a constant speed within the movable range, photographs the graphics card at different positions during the constant movement of the lens of the camera module, and obtains a plurality of images by using the image sensor of the camera module, wherein the center of the graphics card is aligned with the center of the image sensor of the camera module, and synchronously obtains the z-axis height value of the lens of the camera module while obtaining each image.
The AA process device 100 can drive a transmission mechanism connected with a lens of the camera module by controlling a motor, so that the lens of the camera module moves from a starting position to a final position in a uniform speed (for example, a lens clamping jaw of the transmission mechanism can drive the lens clamped by the clamping jaw to move from the starting position to the final position in the uniform speed in the movable range), and in the uniform speed moving process of the lens of the camera module, the camera module is controlled to take photos of the graphics card in different positions, namely, in the uniform speed moving process of the lens of the camera module, a dynamic shooting mode is adopted to take photos of the graphics card, the AA process device 100 can acquire a plurality of images from an image sensor of the camera module through an image acquisition card, and the number of the images is enough to satisfy the subsequent steps so as to obtain accurate and complete defocus curve data through the image processing. And simultaneously acquiring the data of the motor encoder to obtain the z-axis height value of the lens of the camera module while acquiring each image (generally, the motor encoder comprises a plurality of groups of differential signals, the differential signals are acquired in real time through an image acquisition card, and the signal change is detected, so that the z-axis height change data of the corresponding lens can be obtained, and the z-axis height value of the lens is obtained). The center of the image card and the center of the image sensor of the camera module are well aligned before the camera module is actively aligned.
Optionally, in step S102, photographing the graphics card at different positions includes:
the cards were photographed at random at different locations.
In the process of uniform movement of the lens of the camera module, the AA processing device 100 can randomly send a photographing control signal through the image acquisition card, and randomly photograph the image card at different positions.
Optionally, in step S102, photographing the graphics card at different positions includes:
and photographing the graphic card at the multiple position of the preset step length.
In the process of uniform movement of the lens of the camera module, the AA processing device 100 may also send a photographing control signal through the image acquisition card according to a preset time interval, and photograph the image card when the lens uniformly moves to a multiple position of a preset step length.
Continuing in this embodiment, in step S103, the AA processing apparatus 100 determines a central ROI area of each image and at least two ROI areas other than the central ROI area, calculates SFR values of the at least three ROI areas of each image according to patterns in the at least three ROI areas, and obtains defocus curves of the at least three ROI areas based on the SFR values of the at least three ROI areas of each image and z-axis height values of lenses corresponding to the images, respectively
After the image acquisition card of the AA processing apparatus 100 acquires the image and the z-axis height value of the lens corresponding to the image, the image acquisition card is sent to the host computer of the AA processing apparatus 100 to process the data. Because the image card at least comprises a plurality of patterns at a center position and other different positions (generally comprises various direction positions of different view angles such as 0.7 view angle, etc.), the image has corresponding patterns at the center and outside the center. A central ROI (Region Of Interest ) region and at least two ROI regions outside the central ROI region of each image may be determined, wherein each ROI region has a pattern therein, and then respective SFR (Spatial Frequency Response ) values for the ROI regions of each image are calculated based on the patterns in the at least three ROI regions, respectively. Generally, the z-axis height of the lens of the camera module is different, the SFR values of the same ROI area in the synchronously captured images are different, and the SFR value of each ROI area changes along with the change of the z-axis height of the lens of the camera module. In the process that the lens of the camera module moves from the initial position to the end position in the movable range at a constant speed, for each ROI (region of interest) region, SFR (small form factor) values corresponding to the lens of the camera module under different z-axis height values can be calculated, a two-dimensional coordinate system can be constructed by the lens z-axis height values and the SFR values, for each ROI region, the different lens z-axis height values and the SFR values corresponding to the different lens z-axis height values are a plurality of discrete points in the two-dimensional coordinate system, curve fitting is carried out on the discrete points, and then the defocusing curves of the ROI regions corresponding to the camera module can be obtained.
In this embodiment, in step S104, the AA processing apparatus 100 obtains the tilt angle of the lens of the camera module according to the obtained defocus curves of the at least three ROI areas.
Optionally, the step S104 includes:
determining a z-axis height value corresponding to a peak point of the defocusing curves of the at least three ROI areas and an x/y-axis coordinate value of a feature point of a pattern in the corresponding ROI area based on the defocusing curves of the at least three ROI areas;
and carrying out plane fitting according to the z-axis height values corresponding to the peak points of the defocusing curves of the at least three ROI areas and the x/y-axis coordinate values of the characteristic points of the patterns in the corresponding ROI areas to obtain a fitting plane, and determining the included angle between the fitting plane and the plane of the image sensor of the camera module as the inclination angle of the lens.
According to the obtained defocus curves of the at least three ROI areas, peak points on the defocus curves of each ROI area can be determined, so that z-axis height values corresponding to the peak points on the defocus curves of each ROI area are determined, and x/y-axis coordinate values of feature points of patterns in each ROI area can be obtained; and then carrying out plane fitting according to the z-axis height value corresponding to the peak point of the defocusing curve of each ROI region and the x/y-axis coordinate value of the characteristic point of the pattern in the corresponding ROI region to obtain a fitting plane, and determining the included angle between the fitting plane and the plane of the image sensor of the camera module as the inclination angle of the lens.
Optionally, the performing plane fitting according to the z-axis height value corresponding to the peak point of the defocus curve of each ROI area and the x/y-axis coordinate value of the feature point of the pattern in the corresponding ROI area includes:
determining a space feature point corresponding to each ROI region according to a z-axis height value corresponding to a peak point of the defocus curve of each ROI region and an x/y coordinate value of a feature point of the pattern in the corresponding ROI region;
and performing plane fitting according to the spatial feature points corresponding to each ROI region.
According to the obtained z-axis height value corresponding to the peak point of the defocus curve of each ROI region of the at least three ROI regions and the x/y coordinate value of the feature point of the pattern in the corresponding ROI region, each ROI region can correspondingly obtain an x/y/z three-axis three-dimensional coordinate value, further, the space feature point corresponding to each ROI region can be determined, at least three space feature points can be obtained altogether, and then plane fitting can be performed according to the space feature points.
Optionally, the feature points of the pattern in the angular ROI area include any one of the following:
centroid of pattern in ROI area;
center point of the pattern in the ROI area.
The feature point of the pattern in each ROI area may be the centroid of the pattern, that is, the average value of x/y coordinate values of all points in the plane graph of all points constituting the pattern, or may be the geometric center point of the pattern.
In this embodiment, in step S105, the AA processing apparatus 100 determines whether the inclination angle, that is, the angle between the fitting plane and the image sensor plane of the camera module meets the preset threshold, and if so, it indicates that no inclination angle adjustment is required for the camera module, and the z-axis height value of the lens can be determined according to the defocus curves of the at least three ROI areas, so as to complete active alignment of the camera module.
Optionally, in step S105, the determining the z-axis height value of the lens based on the defocus curves of the at least three ROI areas includes:
determining a z-axis height value corresponding to a peak point of the defocus curves of each ROI region based on the defocus curves of the at least three ROI regions;
and adding a weight to the z-axis height value corresponding to the peak point of the defocusing curve of each ROI region, calculating a weighted average value, and determining the weighted average value as the z-axis height value of the lens.
According to the obtained defocus curves of each of the at least three ROI areas, the z-axis height value of the lens of the camera module corresponding to the peak point on the defocus curve of each ROI area can be determined, then according to the weight given in advance, the weighted average value of the z-axis height values of the lenses of the camera module corresponding to the peak point on the defocus curves of each of the at least three ROI areas is calculated, and the weighted average value is used as the final z-axis height value of the lenses of the camera module, the AA processing device 100 can drive the transmission mechanism connected with the lenses of the camera module by controlling the motor to drive the clamping jaw, so that the lenses of the camera module move to the positions corresponding to the final z-axis height values, and the active alignment of the camera module is completed.
Optionally, if the inclination angle does not meet a preset threshold, the method further includes:
and performing tilt angle compensation on the lens based on the deviation degree of the tilt angle, controlling the lens to reset to the initial position, repeating the steps until the obtained tilt angle meets a preset threshold, and determining the z-axis height value of the lens based on the defocusing curves of at least three ROI areas obtained currently so as to finish the active alignment of the camera module.
In step S105, if the tilt angle of the lens of the camera module obtained in step S104 does not meet the preset threshold, that is, the tilt angle of the lens exceeds the index requirement, tilt angle compensation is required for the lens. The AA processing apparatus 100 may drive the driving mechanism connected to the lens of the camera module by controlling the motor according to the deviation degree between the currently obtained inclination angle and the preset threshold value, drive the clamping jaw to rotate the lens, perform inclination angle compensation, then control the lens of the camera module to reset to the starting position within the movable range, repeat steps S102 to S105 until the obtained inclination angle meets the preset threshold value, and then perform final positioning on the z-axis height position of the lens to complete active alignment of the camera module.
If the repetition number exceeds the limit, the quality of the camera module is considered to be unqualified, and active alignment can not be continued.
After the active alignment of the camera module is completed, UV curing is typically performed to avoid being affected during the movement of the camera module.
Fig. 2 illustrates an apparatus for active alignment of camera modules according to another aspect of the present application, for performing the method of the above-described method embodiments and/or alternative embodiments, where the apparatus of one embodiment includes:
a machine 110, a jig 120, a clamping jaw 130, a motor 140, a transmission mechanism 150, an image acquisition card 160 and an upper computer 170, wherein,
the jig 120 is fixed on the machine 110 and is used for fixing the camera module;
one end of the clamping jaw 130 clamps a lens 210 of the camera module, the other end of the clamping jaw is horizontally and fixedly connected with the transmission mechanism 150, the transmission mechanism 150 is driven by the motor 140 to drive the clamping jaw 130 to vertically move along the z-axis, and the clamping jaw 130 is controlled to drive the lens to horizontally move and/or rotate along the x/y axis, wherein coded data of an encoder of the motor 140 corresponds to the z-axis height value of the lens one by one;
the image acquisition card 160 is integrated in the upper computer 170 and is respectively and electrically connected with the image sensor 220 of the camera module and the motor 140, when the camera module is controlled to shoot the image card, the image acquired by the image sensor 220 of the camera module is acquired, and the coding data of the coder of the motor 140 are synchronously acquired, so that the z-axis height value of the lens 210 of the camera module is synchronously acquired;
the upper computer 170 is configured to control the image acquisition card 160 to acquire an image and a z-axis height value of the lens 210 of the camera module corresponding to the image, calculate an optical center deviation from the center of the image according to a center point of a pattern in a center ROI area of the image, obtain an defocus curve of each ROI area of at least three ROI areas according to the calculated SFR values of the at least three ROI areas of the image, determine an inclination angle between the lens 210 of the camera module and the image sensor 220, determine a final positioning z-axis height value of the lens 210 of the camera module, output a signal, drive the transmission mechanism 150 through the motor 140, control the clamping jaw 130 to drive the lens 210 of the camera module to move horizontally along an x/y axis to compensate the optical center deviation, control the clamping jaw 130 to drive the lens 210 of the camera module to rotate to perform inclination angle compensation, and control the clamping jaw 130 to move vertically to a position corresponding to the final positioning z-axis height value.
The apparatus in this embodiment is the same as the software and hardware environment of the AA processing apparatus 100 in the foregoing method embodiment and/or the optional embodiment.
It should be noted that, the method embodiments and/or alternative embodiments in the present application may not strictly define the order of execution of the steps, so long as the method embodiments and/or alternative embodiments solve the drawbacks of the prior art, and obtain beneficial effects. The method embodiments herein may be implemented in software and/or a combination of software and hardware. The software programs referred to in this application may be executed by a processor to implement the steps or functions of the embodiments described above. Likewise, the software programs of the present application (including the related data structures) may be stored in a computer-readable recording medium.
Additionally, all or a portion of the various method embodiments and/or alternative embodiments herein may be implemented as a computer program product, e.g., computer program instructions, which, when executed by a computer, cause a method and/or apparatus in accordance with the application to be invoked or otherwise provided for. Program instructions for invoking the methods of the present application may be stored in fixed or removable recording media and/or transmitted via a data stream in a broadcast or other signal bearing medium and/or stored within a working memory of a computer device operating according to the program instructions.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is evident that the word "comprising" does not exclude other elements or steps, and that the singular does not exclude a plurality. The units or means recited in the apparatus claims may also be implemented by means of software and/or hardware. The terms first, second, etc. are used to denote a name, but not any particular order.

Claims (10)

1. A method for active alignment of camera modules, the method comprising:
aligning an optical axis of a lens of a camera module with a center of an image sensor of the camera module;
the lens is controlled to move at a constant speed from a starting position to a final position in a movable range, in the process of moving the lens at a constant speed, a plurality of images are obtained through the image sensor by photographing the image card at different positions, wherein the center of the image card is aligned with the center of the image sensor, and when the images are obtained, the z-axis height value of the lens is synchronously obtained;
determining a center ROI (region of interest) of each image and at least two ROI (region of interest) outside the center ROI, calculating SFR (small form factor) values of the at least three ROI of each image according to patterns in the at least three ROI, and obtaining a defocus curve of the at least three ROI based on the SFR values of the respective ROI of each image and a z-axis height value of a lens corresponding to the image;
obtaining the inclination angle of the lens based on the defocus curves of the at least three ROI areas;
and judging whether the inclination angle meets a preset threshold value, if so, determining a z-axis height value of the lens based on the defocusing curves of the at least three ROI areas so as to finish the active alignment of the camera module.
2. The method of claim 1, wherein aligning an optical axis of a lens of a camera module with a center of an image sensor of the camera module comprises:
photographing the image card at any position in the movable range of the lens of the camera module, and obtaining an image through the image sensor;
determining a center point of a pattern in a center ROI area of the image, and calculating a deviation of the center point from the center of the image;
and carrying out x-axis and/or y-axis compensation on the camera module based on the deviation so as to finish the alignment of the optical axis of the lens and the center of the image sensor.
3. The method of claim 1, wherein photographing the graphics card at different locations comprises:
the cards were photographed at random at different locations.
4. The method of claim 1, wherein photographing the graphics card at different locations comprises:
and photographing the graphic card at the multiple position of the preset step length.
5. The method of claim 1, wherein the obtaining the tilt angle of the lens based on the defocus curves of the at least three ROI areas comprises:
determining a z-axis height value corresponding to a peak point of the defocus curve of each ROI region and an x/y-axis coordinate value of a feature point of the pattern in the corresponding ROI region based on the defocus curves of the at least three ROI regions;
and carrying out plane fitting according to the z-axis height value corresponding to the peak point of the defocusing curve of each ROI region and the x/y-axis coordinate value of the characteristic point of the pattern in the corresponding ROI region to obtain a fitting plane, and determining the included angle between the fitting plane and the plane of the image sensor of the camera module as the inclination angle of the lens.
6. The method of claim 5, wherein performing a plane fit based on the z-axis height value corresponding to the peak point of the defocus curve of each ROI region and the x/y-axis coordinate value of the feature point of the pattern in the corresponding ROI region comprises:
determining a space feature point corresponding to each ROI region according to a z-axis height value corresponding to a peak point of the defocus curve of each ROI region and an x/y coordinate value of a feature point of the pattern in the corresponding ROI region;
and performing plane fitting according to the spatial feature points corresponding to each ROI region.
7. The method of claim 5, wherein the feature points of the pattern in the ROI area comprise any one of:
centroid of pattern in ROI area;
center point of the pattern in the ROI area.
8. The method of claim 1, wherein the determining a z-axis height value of the lens based on defocus curves of the at least three ROI areas comprises:
determining a z-axis height value corresponding to a peak point of the defocus curves of each ROI region based on the defocus curves of the at least three ROI regions;
and adding a weight to the z-axis height value corresponding to the peak point of the defocusing curve of each ROI region, calculating a weighted average value, and determining the weighted average value as the z-axis height value of the lens.
9. The method of claim 1, wherein if the tilt angle does not meet a preset threshold, the method further comprises:
and performing tilt angle compensation on the lens based on the deviation degree of the tilt angle, controlling the lens to reset to the initial position, repeating the steps until the obtained tilt angle meets a preset threshold, and determining the z-axis height value of the lens based on the defocusing curves of at least three ROI areas obtained currently so as to finish the active alignment of the camera module.
10. An apparatus for performing the method of any one of claims 1 to 9, the apparatus comprising:
the machine comprises a machine table, a jig, clamping jaws, a motor, a transmission mechanism, an image acquisition card and an upper computer, wherein,
the jig is fixed on the machine table and used for fixing the camera module;
one end of the clamping jaw clamps the lens of the camera module, the other end of the clamping jaw is horizontally and fixedly connected with the transmission mechanism, the transmission mechanism is driven by the motor to drive the clamping jaw to vertically move along the z-axis, and the clamping jaw is controlled to drive the lens to horizontally move and/or rotate along the x/y-axis, wherein the coded data of the encoder of the motor corresponds to the z-axis height value of the lens one by one;
the image acquisition card is integrated in the upper computer and is respectively and electrically connected with the image sensor of the camera module and the motor, when the camera module is controlled to shoot the image card, an image acquired by the image sensor is acquired, and coding data of an encoder of the motor is acquired so as to synchronously acquire the z-axis height value of the lens;
the upper computer is used for controlling the image acquisition card to acquire an image and a z-axis height value of the lens corresponding to the image, calculating optical center deviation with the center of the image according to a center point of a pattern in a center ROI (region of interest) area of the image, obtaining a defocusing curve of at least three ROI areas according to SFR (small form factor) values of at least three ROI areas of the image obtained through calculation, determining an inclined angle between the lens and the image sensor, determining a final positioning z-axis height value of the lens, outputting a signal, driving the transmission mechanism through the motor, controlling the clamping jaw to drive the lens to horizontally move along an x/y axis so as to compensate the optical center deviation, controlling the clamping jaw to drive the lens to rotate so as to compensate the inclined angle, and controlling the clamping jaw to vertically move to a position corresponding to the final positioning z-axis height value of the lens.
CN202311142576.7A 2023-09-05 2023-09-05 Method and device for active alignment of camera module Pending CN117270229A (en)

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