Diffractive lens optical engine interface structure and assembly method for integrated ar module

Abstract

The present invention relates to the technical field of AR optical module assembly, specifically to a diffractive lens optical machine interface structure and an assembly method for an integrated AR module. The method includes: extracting the reference plane of the frame and the optical center and axis position reference data of the diffractive lens to form a frame-lens combination, and then extracting the axis and end spherical center coordinates of the optical machine positioning posts on the outer side of the light exit port of the projection optical machine housing, importing them into the assembly coordinate system, calculating the theoretical vertical distance between the axis of the positioning post and the reference plane of the frame to generate installation pose data, and driving the optical machine to move until the end spherical center of the positioning post contacts the reference plane of the frame to complete the initial positioning. Detect the deviation of the initial positioning posture, control the elastic preloading mechanism of the frame assembly to generate corresponding elastic deformation, and use the deformation reaction force to push the optical machine for secondary adjustment until the posture deviation converges to the set threshold to complete the assembly. The present invention also provides an optical machine interface structure matching the assembly method.

Description

Technical Field

[0001] This invention relates to the field of AR optical module assembly technology, and in particular to the diffraction lens optomechanical interface structure and assembly method for integrated AR modules. Background Technology

[0002] Currently, the assembly of the diffractive lens optical engine interface of integrated AR modules mostly adopts conventional mechanical positioning and mating methods. The assembly positioning is achieved by relying on the positioning structure of the projection optical engine housing and the rigid mating of the lens frame assembly. During the assembly process, the positioning structure parameters are obtained through conventional coordinate acquisition methods. In the initial positioning stage, the position is limited by the surface contact between the positioning column and the reference surface of the lens frame. The attitude deviation adjustment is completed by applying external force with the help of external tooling equipment.

[0003] In conventional assembly schemes, the contact between the end structure of the positioning post and the reference surface of the lens frame is prone to contact position offset. It is impossible to accurately calculate the distance between the positioning post axis and the reference surface using precise coordinate parameters, and the initial positioning accuracy is significantly affected by mechanical fit tolerances. The attitude deviation generated after initial positioning cannot be adjusted in conjunction with the lens frame's own structure, and the adjustment force of external tooling is insufficient to match the deviation correction requirements. The convergence process of the attitude deviation is lag-dependent, making it unsuitable for the high-precision assembly requirements of the AR diffraction lens's optomechanical interface.

[0004] This avoids the precision deviation in positioning between the end of the optical positioning post and the reference surface of the lens frame, and eliminates the assembly drawback that the attitude deviation after initial positioning cannot be adaptively adjusted by the elastic structure of the lens frame assembly. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a diffraction lens optomechanical interface structure and assembly method for an integrated AR module.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for assembling the optomechanical interface of a diffractive lens integrated with an AR module, comprising: Extract the frame reference plane data from the frame assembly to be assembled, and form a frame-lens assembly based on the frame reference plane data, the optical center data of the diffractive lens, and the axis reference data. The optical engine positioning post data is extracted from the projection optical engine housing to be assembled. The optical engine positioning post data includes the axis and end sphere center coordinates of the optical engine positioning post. The optical engine positioning post is located outside the light outlet of the projection optical engine housing. The optomechanical positioning post data is imported into the assembly coordinate system of the lens frame assembly, the theoretical vertical distance between the axis of the optomechanical positioning post and the reference plane of the lens frame is calculated, and the optomechanical installation pose data is generated. Based on the optical engine mounting posture data, the projection optical engine housing is driven to move toward the lens frame assembly until the center of the end of the optical engine positioning post contacts the reference surface of the lens frame, thus completing the initial positioning of the projection optical engine housing. The attitude deviation of the projection optical engine housing in the initial positioning state is detected, attitude deviation data is generated, and according to the attitude deviation data, the elastic pre-tightening mechanism on the lens frame assembly is controlled to generate corresponding elastic deformation. The reaction force generated by the elastic deformation pushes the projection optical engine housing to perform secondary position adjustment until the attitude deviation data converges to within the set threshold, thus completing the assembly of the diffraction lens optical engine interface structure of the integrated AR module.

[0007] As a further aspect of the present invention, the step of extracting the frame reference plane data from the frame assembly to be assembled includes: A coordinate measuring machine was used to sample three coplanar mechanical positioning reference surfaces on the inner side of the frame at multiple points to obtain the spatial coordinates of each sampling point. A plane fitting operation is performed on the spatial coordinates of each sampling point to generate the mirror frame reference plane data, which represents the normal vector and origin coordinates of the mirror frame reference plane. The mirror frame reference plane data serves as the reference plane for all subsequent position calculations.

[0008] As a further aspect of the present invention, a frame-lens assembly is formed based on the frame reference plane data, the optical center data of the diffractive lens, and the axis reference data, comprising: The reference surface data of the mirror frame consists of the coordinate values ​​of three coplanar mechanical positioning reference surfaces on the inner side of the mirror frame in the assembly coordinate system; The diffractive lens is placed on the frame assembly, the optical center position and axis reference direction of the diffractive lens are measured, the lens center coordinate data and axis reference data are generated, and the lens center coordinate data and axis reference data are corrected based on the frame reference surface data to obtain the corrected lens assembly reference data. Using the corrected lens assembly reference data, the movement trajectory of the dispensing equipment is controlled to apply optical adhesive between the frame reference surface and the diffractive lens, forming a frame-lens assembly with optical adhesive.

[0009] As a further aspect of the present invention, the lens center coordinate data and axis reference data are corrected based on the frame reference surface data to obtain the corrected lens assembly reference data, specifically including: Using the reference plane data of the lens frame as a reference, the angle between the current normal vector of the diffractive lens and the normal vector of the reference plane of the lens frame is calculated, and the angle deviation is generated. Based on the angular deviation, the lens center coordinate data is rotated around the Z-axis for compensation, and the axis reference direction is corrected. Simultaneously, with the frame reference plane as the Z-axis zero point, the Z-value of the lens center coordinate data is height compensated to obtain the corrected lens assembly reference data. Using the corrected lens assembly reference data, the movement trajectory of the dispensing equipment is controlled to apply optical adhesive between the frame reference surface and the diffractive lens, specifically including: Using the corrected lens assembly reference data as the center and in conjunction with the axis reference direction, a closed annular dispensing path or a segmented dispensing path is planned according to the preset adhesive path width. The dispensing head is controlled to move at a constant speed along the annular dispensing path, and during the movement, optical adhesive is released at a constant dispensing rate. After the dispensing head completes one revolution, the dispensing stops and the head is lifted to form an adhesive layer of uniform thickness. The adhesive layer is used to connect the reference surface of the lens frame and the diffractive lens.

[0010] As a further aspect of the present invention, the step of extracting the optical engine positioning post data from the projection optical engine housing to be assembled includes: Visual scanning is performed on the outer side of the light outlet of the projection optical engine housing to identify the outline of the optical engine positioning post and extract the geometric center axis of the optical engine positioning post. Using the geometric center axis as a reference, extend towards the end of the optomechanical positioning post, calculate the three-dimensional coordinates of the end sphere's center, and use the dataset containing the geometric center axis and the end sphere's center coordinates as the optomechanical positioning post data.

[0011] As a further aspect of the present invention, the optomechanical positioning post data is imported into the assembly coordinate system of the lens frame assembly, the theoretical vertical distance between the axis of the optomechanical positioning post and the reference plane of the lens frame is calculated, and optomechanical mounting pose data is generated, including: Read the coordinate system parameters of the current assembly station and convert the end sphere center coordinates in the optomechanical positioning column data to the assembly coordinate system; The frame reference surface data is called to calculate the vertical distance from the end sphere center coordinates to the frame reference surface. The vertical distance is compared with the preset standard assembly gap to generate the height adjustment amount. The height adjustment amount is combined with the coordinates of the end sphere center to form the optomechanical mounting pose data containing three translational degrees of freedom: X, Y, and Z.

[0012] As a further aspect of the present invention, detecting the attitude deviation of the projection optical engine housing in the initial positioning state and generating attitude deviation data includes: A laser displacement sensor is installed at a preset position on the projection engine housing, and the detection beam emitted by the laser displacement sensor is perpendicular to the reference plane of the lens frame. The laser displacement sensor is activated to collect displacement feedback values ​​at at least three non-collinear positions on the surface of the projection optical engine housing, generating a displacement feedback dataset. The displacement feedback dataset is compared with the theoretical standard plane data, and the tilt angle and offset of the projection optical engine housing are calculated by the least squares method to generate the attitude deviation data.

[0013] As a further aspect of the present invention, based on the attitude deviation data, the elastic pre-tightening mechanism on the lens frame assembly is controlled to generate corresponding elastic deformation, and the reaction force generated by the elastic deformation pushes the projection optical engine housing to perform a secondary position adjustment, including: The attitude deviation data is analyzed and decomposed into thrust in the X-axis direction, thrust in the Y-axis direction, and torque about the Z-axis. Based on the thrust in the X-axis direction and the thrust in the Y-axis direction, the piezoelectric ceramic actuators in the two elastic pre-tightening mechanisms located on both sides of the lens frame assembly are controlled to generate corresponding extension and retraction amounts, so that the two elastic pre-tightening mechanisms apply thrust in the corresponding direction to the projection optical engine housing respectively. Based on the torque of rotation around the Z-axis, the voice coil motor in the third elastic pre-tightening mechanism located at the bottom of the lens frame assembly is controlled to generate a vertical displacement, and a rotational correction torque is applied to the projection optical engine housing through the lever principle to achieve multi-degree-of-freedom correction.

[0014] As a further aspect of the present invention, the assembly of the diffraction lens optomechanical interface structure of the integrated AR module is completed until the attitude deviation data converges to within a set threshold, including: After each action of the elastic pre-tightening mechanism, the step of detecting the attitude deviation of the projection optical engine housing in the initial positioning state is repeated to obtain new attitude deviation data; The difference between the new attitude deviation data and the attitude deviation data from the previous round is calculated to obtain the change in deviation. If the deviation change is less than the set threshold, the step of controlling the elastic preload mechanism to generate deformation is continued in a loop. If it is, the assembly process is determined to be over and the current state of all elastic preload mechanisms is locked.

[0015] As a further aspect of the present invention, the present invention also includes a diffractive lens optical-mechanical interface structure for integrating an AR module. The structure includes a lens frame assembly, a diffractive lens, a projection optical engine housing, an optical-mechanical positioning post, a lens frame reference surface, an elastic pre-tightening mechanism, and an optical adhesive layer located between the lens frame reference surface and the diffractive lens. The optical-mechanical positioning post forms a spherical contact with the lens frame reference surface for initial positioning, and the elastic pre-tightening mechanism is used to provide an adjustable reaction force required for attitude compensation after initial positioning.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are as follows: The coordinates of the axis and end sphere center of the optical engine positioning post are extracted, and this coordinate data, together with the reference surface of the lens frame and the optical center and axis reference data of the diffractive lens, are imported into the assembly coordinate system of the lens frame assembly. The theoretical perpendicular distance between the axis of the optical engine positioning post and the reference surface of the lens frame is calculated, and the optical engine mounting pose data is generated. The projection optical engine housing is driven to move until the end sphere center of the optical engine positioning post contacts the reference surface of the lens frame to complete the initial positioning. The point contact between the end sphere center and the reference surface of the lens frame weakens the influence of the fit tolerance in the contact area and improves the consistency of the module assembly reference.

[0017] The system detects the attitude deviation of the projection engine housing in its initial positioning state and generates attitude deviation data. Based on this data, it controls the elastic pre-tightening mechanism on the lens frame assembly to generate corresponding elastic deformation. The reaction force of the elastic deformation pushes the projection engine housing to complete a secondary position adjustment until the attitude deviation data converges to a set threshold. The elastic deformation of the elastic pre-tightening mechanism and the attitude deviation data form a one-to-one matching relationship. The direction of the reaction force is consistent with the actual needs of deviation correction. The secondary position adjustment process does not require the intervention of external tooling, the adjustment adaptability of the assembly structure is enhanced, and the continuity of the attitude deviation convergence process is improved. Attached Figure Description

[0018] Figure 1 This is a flowchart of the assembly method for the diffractive lens optomechanical interface of the integrated AR module described in this invention; Figure 2 Flowchart for position correction and dispensing control; Figure 3 A flowchart for generating optomechanical mounting pose data; Figure 4 A graph showing the trend of the multi-round correction force / torque variation of the elastic preload mechanism; Figure 5 This is a graph showing the trend of changes in the adjustment amount of the driving element over multiple iterations. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] See Figure 1 The process involves extracting the lens frame reference surface data from the lens frame assembly to be assembled, and forming a lens frame assembly based on this data. Next, the process extracts the optical engine positioning post data from the projection optical engine housing to be assembled. This data includes the axis and end sphere center coordinates of the optical engine positioning post, which is located outside the light outlet of the projection optical engine housing. The optical engine positioning post data is imported into the assembly coordinate system of the lens frame assembly, and the theoretical perpendicular distance between the axis of the optical engine positioning post and the lens frame reference surface is calculated, generating optical engine mounting pose data. Based on this pose data, the projection optical engine housing is driven to move towards the lens frame assembly until the end sphere center of the optical engine positioning post contacts the lens frame reference surface, completing the initial positioning of the projection optical engine housing. The attitude deviation of the projection optical engine housing in the initial positioning state is detected, attitude deviation data is generated, and according to the attitude deviation data, the controllable micro-displacement actuator, i.e. elastic pre-tightening mechanism, on the lens frame assembly is controlled to generate corresponding elastic deformation. The reaction force generated by the elastic deformation pushes the projection optical engine housing to perform secondary position adjustment until the attitude deviation data converges to within the set threshold, thus completing the assembly of the diffraction lens optical engine interface structure of the integrated AR module.

[0022] In one embodiment of the present invention, the frame assembly is fixed to a high-precision measurement platform. A contact probe of a coordinate measuring machine (CMM) samples three coplanar mechanical positioning reference planes on the inner side of the frame at multiple points. The CMM drives the probe to collect at least three non-collinear sampling points on the reference plane, acquiring the spatial coordinate data of each sampling point. These spatial coordinate data constitute an initial set of measurement points. After acquiring the spatial coordinates of each sampling point, a plane fitting operation is performed on the spatial coordinates of each sampling point in the measurement point set. The plane fitting operation uses the least squares method for calculation, and the optimization objective function of the plane fitting operation is... Represented as: in: Representing the The three-dimensional coordinates of each sampling point, parameters and The normal vector representing the fitted plane is in and Component coefficients of direction, parameters The fitted plane is in Intercepts along the axial direction. The parameters are obtained by solving. , , Then, the general equation of a plane can be transformed into one that includes the normal vector. and through the origin coordinates The point-normal expression. The generated mirror frame reference plane data represents the normal vector and origin coordinates of the mirror frame reference plane. The mirror frame reference plane data serves as the global reference plane for all subsequent position calculations.

[0023] In practice, the definition of the lens frame reference plane equation relies on a high-precision 3D measurement system, such as a laser tracker or structured light scanner. The lens frame assembly is fixed to a fixture at the assembly station. The measurement system scans the annular plane on the lens frame assembly that supports the diffractive lenses. This annular plane is typically precision-machined and has high flatness. The measurement system acquires the 3D coordinate data of at least three non-collinear points on this annular plane; these points are usually distributed along the edge of the annular plane or at specific marked locations. The acquired point cloud data is fitted to the plane using the least squares method to obtain the mathematical equation of the lens frame reference plane. The equation of the lens frame reference plane is typically expressed in a general form: in: , , These are the three components of the normal vector to the reference plane of the mirror frame. It is a constant term. This represents the X-axis coordinate of the frame assembly in the assembly coordinate system. This represents the Y-axis coordinate of the frame assembly in the assembly coordinate system. This represents the Z-axis coordinate of the frame assembly in the assembly coordinate system. Normal vector. The direction is perpendicular to the frame reference plane, pointing towards the inside or outside of the frame assembly; the specific direction is determined according to the assembly coordinate system. Constant term. The position of the mirror frame reference plane in space is determined, and its value is related to the choice of the origin of the assembly coordinate system. In specific implementation, the parameters of the mirror frame reference plane equation... , , , It is stored in the memory of the control system as a geometric reference for subsequent calculations of lens center coordinate data correction and import of optomechanical positioning column data.

[0024] In some embodiments, the mirror frame reference surface data is loaded into the coordinate system parameter table of the assembly control system. The mirror frame reference surface data consists of the coordinate values ​​of the three coplanar mechanical positioning reference surfaces on the inner side of the mirror frame in the assembly coordinate system. The coordinate values ​​of the mirror frame reference surface data correspond to the coordinate values ​​in the assembly coordinate system. , , Position and direction cosines. The diffractive lens is picked up and placed above the lens frame assembly with the assistance of a vacuum suction gripper. A non-contact optical sensor mounted at the end of the robotic arm measures the geometric center position of the diffractive lens. The optical sensor scans along the edge contour of the diffractive lens, and a center-fitting algorithm calculates the coordinates of the current center point of the diffractive lens in the sensor coordinate system. After coordinate transformation, the lens center coordinate data is generated. Position correction of the lens center coordinate data based on the lens frame reference plane data is necessary. The position correction process uses the lens frame reference plane data as a spatial reference, compares the directional difference between the current normal vector of the diffractive lens and the normal vector of the lens frame reference plane, generates a rotation compensation matrix, and simultaneously compares the lens center with the lens frame reference plane in terms of direction. The height difference along the axis generates a translation compensation vector. After obtaining the corrected lens assembly reference data, the corrected lens assembly reference data is transmitted to the CNC system of the dispensing equipment. Based on the corrected lens assembly reference data and the preset glue path width parameters, the CNC system plans a closed loop dispensing path. The trajectory of the dispensing path is a continuous curve in three-dimensional space.

[0025] In practice, the motion trajectory of the dispensing equipment is controlled using the corrected lens assembly reference data. The motion trajectory of the dispensing equipment is decomposed into... , , The axis linkage command causes the dispensing head, under the control of the CNC system, to move to the planned starting position. It then activates the pressure control valve, releasing optical adhesive at a constant dispensing rate. The dispensing head continuously and uniformly displaces along a circular dispensing path. This means the optical adhesive is evenly applied to a predetermined area between the lens frame reference plane and the diffractive lens. After the dispensing head completes one continuous rotation, the pressure control valve closes, and the dispensing head continues its continuous movement along the circular dispensing path. The axis is lifted, and the optical adhesive forms a uniformly thick annular layer under the combined action of surface tension and gravity. After the annular layer cures, it forms an adhesive structure connecting the frame reference surface and the diffractive lens. It can be understood that the frame-lens assembly with the optical adhesive is then transferred to a curing station, where the optical adhesive cures under ultraviolet light or heat radiation, forming a structurally stable frame-lens assembly.

[0026] In one embodiment of the present invention, see [reference] Figure 2 Position correction is based on the reference plane data of the mirror frame, and the normal vector of the reference plane data is defined as follows: The normal vector of the current plane of the diffraction lens, measured by the optical sensor, is defined as... Calculate the angle between the current normal vector of the diffractive lens and the normal vector of the lens frame reference plane, generating the angle deviation. The calculation formula is: in: This represents the dot product of two normal vectors. and These represent the magnitudes of the two normal vectors. Angular deviation. The unit is radians, representing the angular deviation between the plane of the diffractive lens and the reference plane of the frame. Based on the angular deviation, the lens center coordinate data is re-evaluated. The rotational compensation of the shaft, the control system will calculate the angular deviation. Convert to rotation matrix Rotation matrix The position vector acting on the original lens center coordinate data. In practice, rotation compensation is performed with the origin of the lens frame assembly coordinate system as the rotation center, rotating the center point coordinates of the diffractive lens around... Axis rotation angle This is to eliminate the angular deviation of the diffraction lens on the horizontal plane. Meanwhile, the reference plane of the lens frame is used as... Towards zero, the frame reference plane is the height reference plane in the assembly space, representing the coordinate data of the lens center. The value is height compensated, and the height compensation process involves calculating the center point of the current diffraction lens. The coordinates and the equations of the reference plane of the mirror frame are in the corresponding Theory at location The difference between the coordinates is calculated and added as a compensation to the lens center coordinate data. After obtaining the corrected lens assembly reference data, the corrected lens assembly reference data is a dataset containing the corrected coordinates. A complete pose description including coordinates and normal vectors.

[0027] In some embodiments, the process of controlling the motion trajectory of the dispensing device using the corrected lens assembly reference data involves using the corrected lens assembly reference data as the center and the projection point of the corrected lens assembly reference data on the plane. The center is set. Based on the preset adhesive path width, a closed loop dispensing path is planned, with the adhesive path width... It is a preset process parameter; the circular dispensing path is centered on the circle. Centered on, with radius The circle, in which The value of [value] satisfies the requirement that the adhesive line formed on the reference surface of the lens frame completely surrounds the bonding area of ​​the diffractive lens. The dispensing head is controlled to move at a uniform speed along the circular dispensing path; the speed of the dispensing head... It is a constant value, and the trajectory of the motion is a spatial circle in three-dimensional space. The projection on the plane is the planned circular path described above. In the axial direction, the nozzle of the dispensing head maintains a constant height with the reference surface of the lens frame. During operation, the internal air pressure control system of the dispensing equipment releases the optical adhesive at a constant dispensing rate. Speed ​​of dispensing head movement and glue path width Together, these factors determine the final cross-sectional dimensions of the adhesive layer. After the dispensing head completes one revolution, the control system sends a shut-off signal to the pressure control valve, stopping the dispensing and controlling the dispensing head to move along... The dispensing head is lifted upwards along the axis, with a lifting distance greater than the expected thickness of the adhesive layer, to prevent it from contacting uncured adhesive during its departure. This forms an adhesive layer of uniform thickness, which serves as the physical medium connecting the frame reference plane and the diffractive lens. The thickness and uniformity of the adhesive layer are determined by the dispensing rate, the speed of the dispensing head, and the height between the dispensing head and the reference plane. Under surface tension, the adhesive layer exhibits a near-semi-circular cross-section, and after curing, it forms an optical adhesive structure with a certain degree of elasticity and adhesion.

[0028] Optionally, a small offset can be introduced when generating the circular dispensing path. To compensate for the shrinkage effect of optical adhesives during the curing process, offset The radius of the circle added to the plan This ensures that the actual inner or outer diameter of the adhesive path is slightly larger or smaller than the design value, guaranteeing that the adhesive layer will be accurately positioned after curing. It can be understood that the entire position correction and dispensing control process is completed within a closed-loop system. The system reads the sensor feedback data in real time and compares it with the corrected lens assembly reference data to ensure motion accuracy. In some embodiments, when the dispensing head moves along the annular dispensing path, it may employ a multi-turn spiral progressive path to fill a wider bonding area. In this case, the radius of each turn will increase according to a preset increment. By sequentially increasing or decreasing the number of nozzles, a continuous spiral adhesive path is formed. While controlling the dispensing head to move at a constant speed along the circular dispensing path, the orientation of the dispensing head can also be dynamically fine-tuned according to changes in the curvature of the adhesive path, ensuring that the nozzle axis of the dispensing head is always perpendicular to the tangent direction at the point where the adhesive path is located, thus guaranteeing the uniformity of adhesive dispensing.

[0029] In one embodiment of the present invention, the process of extracting optical engine positioning post data from the projection optical engine housing to be assembled involves visually scanning the outer side of the light outlet of the projection optical engine housing. This visual scanning is performed by a high-resolution industrial camera in conjunction with a structured light projector. The structured light pattern is projected onto the surface of the projection optical engine housing, and the industrial camera captures an image with structured light stripes. Two optical engine positioning posts are provided on the projection optical engine housing, both with spherical ends. The axes of the two positioning posts are not collinear, forming a stable two-point spherical contact with the reference surface of the lens frame, thus providing better constraint during initial positioning. The contours of the optical engine positioning posts are identified, and an image processing algorithm performs edge detection and feature matching on the acquired image to identify the pixel region of the optical engine positioning posts in the image. The geometric center axis of the optical engine positioning posts is extracted; this geometric center axis is the centerline obtained by cylindrical fitting of the cylindrical point cloud data of the optical engine positioning posts. Based on the geometric center axis, the optical-mechanical positioning post extends to its end, which is designed as a sphere. The three-dimensional coordinates of the center of the sphere at the end are calculated by fitting the point cloud data of the end of the optical-mechanical positioning post. The dataset containing the coordinates of the geometric center axis and the center of the sphere at the end is used as the optical-mechanical positioning post data, which is stored in the control system in the form of a data file.

[0030] In practice, the optomechanical positioning column data is imported into the assembly coordinate system of the lens frame assembly. This assembly coordinate system is a global coordinate system referenced to the lens frame's reference plane. (See also...) Figure 3 Read the coordinate system parameters of the current assembly station. The coordinate system parameters include the homogeneous transformation matrix of the assembly coordinate system relative to the vision sensor coordinate system. The coordinates of the end sphere center in the optomechanical positioning post data are transformed to the assembly coordinate system using the following formula: in: Representing the coordinates of the end sphere's center measured in the vision sensor's coordinate system, it is a 4x1 homogeneous coordinate vector. ; This represents a 4x4 homogeneous transformation matrix from the sensor coordinate system to the assembly coordinate system. This represents the coordinates of the end sphere center in the assembly coordinate system after transformation. The frame reference plane data is retrieved, and the perpendicular distance from the end sphere center coordinates to the frame reference plane is calculated. The equation of the frame reference plane has been defined in one of the above embodiments. End center coordinates vertical distance to the plane The calculation formula is Vertical distance With the preset standard assembly clearance Compare and generate height adjustment amount. ,when When the value is positive, it indicates that the center of the ball at the end of the optomechanical positioning post is higher than the theoretical contact position, and it needs to be adjusted downwards; when... A negative value indicates that an upward adjustment is needed. The height adjustment amount... coordinates of the end sphere center of , Components are combined to form a group containing , , Optomechanical mounting pose data with three translational degrees of freedom can be represented as pose vectors. The first three components represent the target position, and the last three components represent the attitude.

[0031] In some embodiments, the geometric central axis of the optomechanical positioning post is represented as a direction vector during visual scanning. and through its point The equation of the line, the direction vector It also requires the use of coordinate transformation matrices. Transform to the assembly coordinate system to obtain the direction vector. The conversion relationship is as follows ,in It is a transformation matrix The 3x3 rotation matrix part. When calculating the theoretical perpendicular distance between the axis of the optomechanical positioning post and the reference plane of the lens frame, the direction of the axis of the optomechanical positioning post is... Normal vector to the reference plane of the frame The angle between It also needs to be calculated to assess whether the optical positioning post is perpendicular to the frame reference plane, and the included angle. The calculation is similar to the angle calculation in one of the above embodiments. It can be understood that the generated optomechanical mounting pose data includes not only position adjustment amounts, but also, in actual implementation, the angle between the axial direction and the normal vector of the reference plane. The calculated attitude adjustment is used to pre-correct the angle of the projection engine housing before initial positioning. Optionally, the visual scanning process can employ multi-view reconstruction technology, which involves photographing the projection engine housing from multiple angles and using stereo vision principles to reconstruct a complete 3D point cloud model of the optical engine positioning post and its end spherical surface, thereby more accurately extracting the geometric center axis and the coordinates of the end sphere center. In some embodiments, a preset standard assembly gap is used. It is not a fixed value, but a tolerance range allowed by the optical design. The control system will compare vertical distances Whether it falls within this tolerance zone, if exist Within the range, the height adjustment amount Set to zero, no action required. To adjust; if If it exceeds this range, then proceed as follows: Calculate the adjustment amount, where This is the median of the tolerance range. It can be understood that importing the optomechanical positioning column data into the assembly coordinate system of the lens frame assembly is a crucial step in coordinate unification. It ensures that data from different measuring devices (vision sensors, coordinate measuring machines) can be calculated and compared under the same spatial reference, thereby driving subsequent assembly actions.

[0032] In one embodiment of the present invention, the process of detecting the attitude deviation of the projection optical engine housing in its initial positioning state and generating attitude deviation data involves installing a laser displacement sensor at a preset position on the projection optical engine housing. The laser displacement sensor is a non-contact ranging device mounted on an independent bracket. The detection beam emitted by the laser displacement sensor is perpendicular to the reference plane of the lens frame. The installation angle of the laser displacement sensor is precisely adjusted so that the direction of its emitted laser beam is parallel to the normal vector of the reference plane of the lens frame. The laser displacement sensor is activated, and displacement feedback values ​​are collected at at least three non-collinear positions on the surface of the projection optical engine housing. The laser displacement sensor measures the flight time or phase difference of the laser beam from the sensor to the measurement points on the surface of the projection optical engine housing according to a set sampling frequency, converting this into distance values ​​to generate a displacement feedback dataset. The displacement feedback dataset contains the coordinates of multiple measurement points and their corresponding distance measurements. The displacement feedback dataset is compared with theoretical standard plane data. The theoretical standard plane is an ideal plane preset according to assembly requirements, typically parallel to the reference plane of the lens frame and at a set theoretical distance. The tilt angle and offset of the projection optical engine housing are calculated using the least squares method to generate attitude deviation data. Attitude deviation data is calculated by solving for the plane equation parameters that minimize the sum of the squared distances from the measurement point to the fitting plane. After obtaining the equation parameters of the fitting plane, the attitude deviation data can be quantified as the deviation of the fitting plane relative to the theoretical standard plane. Rotation angle of the axis , around Rotation angle of the axis And in Translation in the axial direction .

[0033] Table 1: Laser Displacement Sensor Measurement Point Layout and Example Data Table Note: The theoretical standard distance is 2.000mm, and the calculated deviation is [not specified]. .

[0034] Based on the attitude deviation data, the elastic pre-tightening mechanism on the control frame assembly generates corresponding elastic deformation. The reaction force generated by this elastic deformation pushes the projection engine housing for secondary position adjustment. The attitude deviation data is analyzed and decomposed into... Thrust in the axial direction and Thrust in the axial direction, and around The torque of shaft rotation. The decomposed calculation is based on the layout of the elastic preload mechanism and the lever arm length, where Thrust in the axial direction With and around Rotation angle of the axis Related, Thrust in the axial direction With and around Rotation angle of the axis Related, around Torque of shaft rotation Related to torsional deformation of the plane. According to Thrust in the axial direction and The axial thrust controls the piezoelectric ceramic actuators in the two elastic preload mechanisms located on both sides of the lens frame assembly to generate corresponding extension and retraction. The piezoelectric ceramic actuators generate nanometer-level displacements based on the received voltage signals, causing the two elastic preload mechanisms to apply thrust in the corresponding direction to the projection engine housing. (Based on the...) The torque of the shaft rotation controls the voice coil motor in the third elastic preload mechanism located at the bottom of the frame assembly to generate a vertical displacement. The voice coil motor generates linear motion according to the received current signal, and its displacement... Calculated using the following formula: in: It is the vertical displacement that the voice coil motor needs to produce. It is a conversion factor related to the lever arm length and structural stiffness. It is the calculated winding The torque of axis rotation. A rotational corrective torque is applied to the projection optical engine housing through the lever principle. The vertical displacement of the voice coil motor pushes a wedge block or connecting rod in contact with the projection optical engine housing, generating a horizontal torque to achieve multi-degree-of-freedom correction. In some embodiments, there is a proportional-integral-derivative control relationship between the force or displacement generated by the elastic preload mechanism and the attitude deviation data. The control system calculates the control quantity in real time based on the attitude deviation data and drives the piezoelectric ceramic driver or voice coil motor to operate. Optionally, the number of laser displacement sensors can be more than three, for example, five or more sensors can be arranged to obtain denser point cloud data of the projection optical engine housing surface. More robust attitude deviation data can be obtained through multi-point fitting, reducing errors caused by anomalies in individual measurement points. It can be understood that the attitude deviation data obtained by least squares comparison not only includes flatness error, but also includes the overall translation and rotation information of the projection optical engine housing relative to the theoretical position. This information is used to generate control commands for the elastic preload mechanism. In practice, there is usually a pre-calibrated nonlinear mapping relationship between the extension and retraction of the piezoelectric ceramic actuator and the required thrust. The control system will calculate the thrust based on this mapping relationship. , This is converted into the corresponding driving voltage value. It can be understood that the third elastic preload mechanism located at the bottom of the frame assembly, in addition to using a voice coil motor, can also employ a precision lead screw driven by a stepper motor to achieve precise control of vertical displacement. Its principle is to convert the rotation of the lead screw into the linear motion of the nut, thereby driving the mechanism to generate a corrective torque.

[0035] See Figure 4 This is a graph showing the trend of force / torque variation in the elastic pre-tightening mechanism over multiple rounds. It illustrates the attenuation changes of X-axis thrust, Y-axis thrust, and torque around the Z-axis during 10 rounds of correction cycles in the assembly process of the AR module diffraction lens optomechanical interface, intuitively reflecting the convergence process of attitude deviation. All three types of forces / torques decrease monotonically with each correction cycle, reflecting the gradual convergence of the projection optical engine housing's attitude deviation. The initial value of the torque around the Z-axis is the highest, with the largest attenuation, making it the main control variable for attitude correction. The initial value of the X-axis thrust is 0.008N, decreasing linearly with each cycle, eventually converging to 0.001N. The initial value of the Y-axis thrust is 0.006N, with an attenuation rate basically synchronized with the X-axis thrust, eventually converging to 0.0005N. All three control variables approach 0 in the 10th cycle, indicating that after 10 rounds of adjustment, the attitude of the projection optical engine housing basically meets the assembly accuracy requirements.

[0036] In one embodiment of the present invention, the attitude deviation data converges to within a set threshold, completing the assembly process of the diffraction lens optical-mechanical interface structure of the integrated AR module. After each action of the elastic pre-tightening mechanism, the step of detecting the attitude deviation of the projection optical engine housing in the initial positioning state is re-executed to obtain new attitude deviation data. After each push or twist action of the elastic pre-tightening mechanism on the projection optical engine housing, the system will have a short stabilization waiting time. After the force between the projection optical engine housing and the elastic pre-tightening mechanism reaches equilibrium and the vibration is eliminated, the control system will trigger the laser displacement sensor again to perform measurement. The step of detecting the attitude deviation of the projection optical engine housing in the initial positioning state is re-executed to obtain new attitude deviation data. The method for obtaining new attitude deviation data is the same as described in the above embodiment. The laser displacement sensor collects displacement feedback values ​​at at least three non-collinear positions on the surface of the projection optical engine housing, generates a new displacement feedback dataset, and calculates the new tilt angle by performing least squares comparison with theoretical standard plane data. , and offset These parameters constitute a new attitude deviation data vector. .

[0037] The difference between the new attitude deviation data and the previous attitude deviation data is calculated to obtain the change in deviation. The difference calculation is an element-wise subtraction operation between vectors. If the previous attitude deviation data was... Then the change in deviation The calculation formula is: in: , Indicates circling The change in the rotation angle of the axis Indicates circling The change in the rotation angle of the axis express The amount of change in the translation. The determination of whether the change in deviation is less than a set threshold is based on comparison. The norm of the vector is related to the value of the set threshold. In practice, the set threshold is usually represented as a vector. ,in It is around The convergence threshold of the axis rotation angle. It is around The convergence threshold of the axis rotation angle. yes The convergence threshold for the translation. The judgment condition is: and and If not, the process continues to cycle through the steps of controlling the deformation of the elastic preload mechanism, i.e., the change in deviation. If the absolute value of any component is not less than its corresponding set threshold, the control system will update the new attitude deviation data. As input, the required thrust and torque for each axis are re-analyzed, and the corresponding piezoelectric ceramic actuators or voice coil motors are driven to make new adjustments. If so, the assembly process is considered complete, and the current state of all elastic preload mechanisms, i.e., the deviation change, is locked. When the absolute values ​​of all components are less than their corresponding set thresholds, the system determines that the position and attitude of the projection engine housing have stabilized and no further adjustment is needed. To ensure optical performance, after the mechanical attitude deviation converges, the system may also include an optical final acceptance step: starting the projection engine and using an image sensor located at the exit pupil to detect the quality or position of the projected light spot, such as center deviation. If the optical indicators do not meet the standards, the controllable micro-displacement actuator can be fine-tuned for compensation until both the mechanical attitude and optical performance standards are met simultaneously.

[0038] In practical implementation, locking the current state of all elastic preload mechanisms typically means applying a latching voltage to the piezoelectric ceramic actuator to maintain its current elongation, and applying a holding current to the voice coil motor to maintain its output force. This ensures that the elastic preload mechanisms continuously apply a stable preload force to the projection engine housing after assembly, preventing displacement during subsequent use. In some embodiments, in addition to determining the amount of deviation change, the system also determines new attitude deviation data. The absolute value of the deviation itself is checked against a more stringent final accuracy threshold to ensure that the absolute accuracy of the assembly meets the requirements. Assembly is considered complete only when the absolute values ​​of both the deviation change and the attitude deviation data meet their respective threshold conditions. Optionally, a threshold can be set. The control system can be dynamically configured according to different product accuracy levels or process requirements. Operators can input different threshold parameters through a human-machine interface. This can be understood as the amount of deviation change. This reflects the actual effect of the previous round of adjustments. The norm is already very small, indicating that the attitude of the projection optical engine housing has tended to be stable, even with new attitude deviation data. The absolute value may still exist, but as long as its change is less than the threshold, the system can be considered to have reached an equilibrium state. Further adjustments may become meaningless due to mechanical hysteresis and measurement noise. In some embodiments, the step of cyclically executing the deformation-generating control elastic preload mechanism may have a maximum iteration limit, such as 20 times, to prevent the system from entering an infinite loop due to certain faults. When the iteration limit is reached and convergence is still not achieved, the system will alarm and pause the assembly process. Before each re-execution of the detection step, the system records the current iteration count and the attitude deviation data from each iteration. Change in deviation This generates an assembly process log for subsequent quality traceability and process analysis.

[0039] See Figure 5 This is a trend chart showing the changes in the adjustment amounts of the driving components during multiple iterations. It illustrates the changes in the displacement adjustment amounts of the piezoelectric ceramics in the X / Y directions and the voice coil motor in the Z direction during 10 iterations of attitude correction in the assembly process of the optical-mechanical interface of the diffractive lens of the AR module. It visually reflects the amplitude and convergence process of the driving components. In iterations 1-4, the initial adjustment amount of the piezoelectric ceramic in the X direction is the largest, rapidly decreasing to approximately 14 μm in the first four iterations, serving as the main driving force for initial attitude correction. The initial adjustment amount of the piezoelectric ceramic in the Y direction is 55 μm, with a decay rate basically synchronized with the X direction, decreasing to approximately 14 μm after four iterations. The initial adjustment amount of the voice coil motor in the Z direction is 35 μm, also decreasing rapidly with the number of iterations, decreasing to approximately 14 μm after four iterations. In iterations 5-8, the X direction fluctuates slightly between 5-14 μm, the Y direction stabilizes at 2-12 μm, and the Z direction fluctuates between 4-10 μm. In iterations 9-10, all three types of adjustment amounts converge to below 2 μm, approaching zero.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for assembling the optomechanical interface of a diffractive lens integrated with an AR module, characterized in that, The method includes: Extract the frame reference plane data from the frame assembly to be assembled, and form a frame-lens assembly based on the frame reference plane data, the optical center data of the diffractive lens, and the axis reference data. The optical engine positioning post data is extracted from the projection optical engine housing to be assembled. The optical engine positioning post data includes the axis and end sphere center coordinates of the optical engine positioning post. The optical engine positioning post is located outside the light outlet of the projection optical engine housing. The optomechanical positioning post data is imported into the assembly coordinate system of the lens frame assembly, the theoretical vertical distance between the axis of the optomechanical positioning post and the reference plane of the lens frame is calculated, and the optomechanical installation pose data is generated. Based on the optical engine mounting posture data, the projection optical engine housing is driven to move toward the lens frame assembly until the center of the end of the optical engine positioning post contacts the reference surface of the lens frame, thus completing the initial positioning of the projection optical engine housing. The attitude deviation of the projection optical engine housing in the initial positioning state is detected, attitude deviation data is generated, and according to the attitude deviation data, the elastic pre-tightening mechanism on the lens frame assembly is controlled to generate corresponding elastic deformation. The reaction force generated by the elastic deformation pushes the projection optical engine housing to perform secondary position adjustment until the attitude deviation data converges to within the set threshold, thus completing the assembly of the diffraction lens optical engine interface structure of the integrated AR module.

2. The method for assembling the diffractive lens optomechanical interface of the integrated AR module according to claim 1, characterized in that, The step of extracting the reference plane data of the frame from the frame assembly to be assembled includes: A coordinate measuring machine was used to sample three coplanar mechanical positioning reference surfaces on the inner side of the frame at multiple points to obtain the spatial coordinates of each sampling point. A plane fitting operation is performed on the spatial coordinates of each sampling point to generate the mirror frame reference plane data, which represents the normal vector and origin coordinates of the mirror frame reference plane. The mirror frame reference plane data serves as the reference plane for all subsequent position calculations.

3. The method for assembling the diffractive lens optomechanical interface of the integrated AR module according to claim 1, characterized in that, Based on the frame reference plane data, the optical center data of the diffractive lenses, and the axis reference data, a frame-lens assembly is formed, including: The reference surface data of the mirror frame consists of the coordinate values ​​of three coplanar mechanical positioning reference surfaces on the inner side of the mirror frame in the assembly coordinate system; The diffractive lens is placed on the frame assembly, the optical center position and axis reference direction of the diffractive lens are measured, the lens center coordinate data and axis reference data are generated, and the lens center coordinate data and axis reference data are corrected based on the frame reference surface data to obtain the corrected lens assembly reference data. Using the corrected lens assembly reference data, the movement trajectory of the dispensing equipment is controlled to apply optical adhesive between the frame reference surface and the diffractive lens, forming a frame-lens assembly with optical adhesive.

4. The method for assembling the diffractive lens optomechanical interface of the integrated AR module according to claim 3, characterized in that, Based on the frame reference surface data, the center coordinate data and axis reference data of the lens are corrected to obtain the corrected lens assembly reference data, specifically including: Using the reference plane data of the lens frame as a reference, the angle between the current normal vector of the diffractive lens and the normal vector of the reference plane of the lens frame is calculated, and the angle deviation is generated. Based on the angular deviation, the lens center coordinate data is rotated around the Z-axis for compensation, and the axis reference direction is corrected. Simultaneously, with the frame reference plane as the Z-axis zero point, the Z-value of the lens center coordinate data is height compensated to obtain the corrected lens assembly reference data. Using the corrected lens assembly reference data, the movement trajectory of the dispensing equipment is controlled to apply optical adhesive between the frame reference surface and the diffractive lens, specifically including: Using the corrected lens assembly reference data as the center and in conjunction with the axis reference direction, a closed annular dispensing path or a segmented dispensing path is planned according to the preset adhesive path width. The dispensing head is controlled to move at a constant speed along the annular dispensing path, and during the movement, optical adhesive is released at a constant dispensing rate. After the dispensing head completes one revolution, the dispensing stops and the head is lifted to form an adhesive layer of uniform thickness. The adhesive layer is used to connect the reference surface of the lens frame and the diffractive lens.

5. The method for assembling the optical-mechanical interface of the diffractive lens of the integrated AR module according to claim 1, characterized in that, The step of extracting the optical engine positioning post data from the projection optical engine housing to be assembled includes: Visual scanning is performed on the outer side of the light outlet of the projection optical engine housing to identify the outline of the optical engine positioning post and extract the geometric center axis of the optical engine positioning post. Using the geometric center axis as a reference, extend towards the end of the optomechanical positioning post, calculate the three-dimensional coordinates of the end sphere's center, and use the dataset containing the geometric center axis and the end sphere's center coordinates as the optomechanical positioning post data.

6. The method for assembling the optomechanical interface of the integrated AR module's diffraction lens according to claim 1, characterized in that, The optomechanical positioning post data is imported into the assembly coordinate system of the lens frame assembly. The theoretical perpendicular distance between the axis of the optomechanical positioning post and the reference plane of the lens frame is calculated to generate optomechanical mounting pose data, including: Read the coordinate system parameters of the current assembly station and convert the end sphere center coordinates in the optomechanical positioning column data to the assembly coordinate system; The frame reference surface data is called to calculate the vertical distance from the end sphere center coordinates to the frame reference surface. The vertical distance is compared with the preset standard assembly gap to generate the height adjustment amount. The height adjustment amount is combined with the coordinates of the end sphere center to form the optomechanical mounting pose data containing three translational degrees of freedom: X, Y, and Z.

7. The method for assembling the optical-mechanical interface of the diffractive lens of the integrated AR module according to claim 1, characterized in that, Detecting the attitude deviation of the projection optical engine housing in the initial positioning state and generating attitude deviation data, including: A laser displacement sensor is installed at a preset position on the projection engine housing, and the detection beam emitted by the laser displacement sensor is perpendicular to the reference plane of the lens frame. The laser displacement sensor is activated to collect displacement feedback values ​​at at least three non-collinear positions on the surface of the projection optical engine housing, generating a displacement feedback dataset. The displacement feedback dataset is compared with the theoretical standard plane data, and the tilt angle and offset of the projection optical engine housing are calculated by the least squares method to generate the attitude deviation data.

8. The method for assembling the optical-mechanical interface of the diffractive lens of the integrated AR module according to claim 1, characterized in that, Based on the posture deviation data, the elastic pre-tightening mechanism on the lens frame assembly is controlled to generate corresponding elastic deformation. The reaction force generated by the elastic deformation pushes the projection optical engine housing to perform a secondary position adjustment, including: The attitude deviation data is analyzed and decomposed into thrust in the X-axis direction, thrust in the Y-axis direction, and torque about the Z-axis. Based on the thrust in the X-axis direction and the thrust in the Y-axis direction, the piezoelectric ceramic actuators in the two elastic pre-tightening mechanisms located on both sides of the lens frame assembly are controlled to generate corresponding extension and retraction amounts, so that the two elastic pre-tightening mechanisms apply thrust in the corresponding direction to the projection optical engine housing respectively. Based on the torque of rotation around the Z-axis, the voice coil motor in the third elastic pre-tightening mechanism located at the bottom of the lens frame assembly is controlled to generate a vertical displacement, and a rotational correction torque is applied to the projection optical engine housing through the lever principle to achieve multi-degree-of-freedom correction.

9. The method for assembling the optomechanical interface of the integrated AR module according to claim 1, characterized in that, The assembly of the diffraction lens optomechanical interface structure of the integrated AR module is completed until the attitude deviation data converges to within a set threshold, including: After each action of the elastic pre-tightening mechanism, the step of detecting the attitude deviation of the projection optical engine housing in the initial positioning state is repeated to obtain new attitude deviation data; The difference between the new attitude deviation data and the attitude deviation data from the previous round is calculated to obtain the change in deviation. If the deviation change is less than the set threshold, the step of controlling the elastic preload mechanism to generate deformation is continued in a loop. If it is, the assembly process is determined to be over and the current state of all elastic preload mechanisms is locked.

10. A diffractive lens optomechanical interface structure integrating an AR module, characterized in that, The assembly includes a lens frame assembly, a diffractive lens disposed on the lens frame assembly, a projection optical engine housing, at least one optical engine positioning post disposed outside the light outlet of the projection optical engine housing, a lens frame reference surface disposed on the lens frame assembly and mates with the center of the end of the optical engine positioning post, an elastic pre-tightening mechanism disposed on the lens frame assembly, and an optical adhesive layer located between the lens frame reference surface and the diffractive lens; the optical engine positioning post is used to form a spherical contact with the lens frame reference surface for initial positioning, and the elastic pre-tightening mechanism is used to apply an adjustable reaction force to the projection optical engine housing after initial positioning to compensate for assembly posture deviation and complete the assembly of the optical engine and the lens frame assembly.

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