A placement head assembly based on direct drive technology for rotation center alignment

Abstract

The present invention discloses a placement head assembly based on direct drive technology for rotation center alignment, comprising a housing, a direct drive rotary platform disposed within the housing, and a force control placement head connected to the direct drive rotary platform; the force control placement head comprises a first connecting block, a nozzle mounting seat, and at least one elastic member, the first connecting block and the nozzle mounting seat being connected at opposite ends of the elastic member; the first connecting block being fixedly connected to the direct drive rotary platform; a nozzle assembly being disposed below the nozzle mounting seat, and a sensing block being disposed at a position where the nozzle mounting seat protrudes from the elastic member; a displacement sensor connected to the direct drive rotary platform and electrically connected to a controller of a placement force control system being disposed directly above the sensing block. The displacement sensor is used to detect the deformation displacement of the elastic member connected to the placement head and feed it back to the controller, and only the nozzle mounting seat and the nozzle assembly are disposed on the elastic member, thereby reducing the load pressure on the elastic member and enabling more accurate control of the placement pressure.

Description

Technical Field

[0001] The invention relates to a mounting head assembly based on direct drive technology and rotation center alignment, belonging to the technical field of automatic mounting equipment. Background Art

[0002] Existing chip pickup methods mostly use a vacuum nozzle. The commonly used structure for this purpose is: a rotary actuator is integrally mounted on a linear guide, with a pressure control assembly connecting the rotary actuator to the guide base. The nozzle is mounted at the front end of the rotary actuator. When the nozzle, carrying the chip, contacts the carrier, the linear guide guides the nozzle tip, which is pressed into the placement head assembly, causing a slight displacement. A scale running in the same direction as the linear guide feeds this displacement information to the controller of the micro voice coil motor (in the pressure control assembly). This controller, using a corresponding algorithm, controls the force applied by the voice coil motor against the chip. In this structure, because the moving parts mounted on the linear guide include the motor for rotation and the scale for feedback, the pressure control assembly must drive a heavy load. When the entire placement device moves at high speeds, the pressure control assembly must apply a reverse torque to prevent the load on the linear guide from moving due to the high speed and thus maintain the load relative to the linear guide. However, the high inertia of the load requires a corresponding reverse torque, which in turn requires a higher-specification motor for the pressure control assembly.

[0003] This structure ultimately results in a heavy overall device, slow force control response, and poor force control accuracy. Furthermore, during force control, the height position feedback from the nozzle end is poorly controlled. Furthermore, to minimize the weight impact, the rotating nozzle head requires an extremely lightweight and complex design. These demanding conditions make it difficult to meet the requirements for high-precision rotation.

[0004] Secondly, in the actual production process, a visual system is required to observe the position of the patch area and compare it with the real-time position of the chip on the nozzle head determined through the nozzle observation window to perform high-precision alignment and placement. However, the observation window component needs to be placed at the position closest to the nozzle end, which has a certain volume and occupies space, and the rotation of the nozzle also requires a motor or belt drive rotation, which will also occupy the best space near the nozzle end. Therefore, in the existing solution, there is a certain conflict between these two structures, and it is difficult to take both into account. A common solution is to use a special nozzle and nozzle holder mechanism with an observation window to replace the rotary actuator of the aforementioned structure, but such a structure loses the ability of the placement device to compensate for the chip angle error during the placement process.

[0005] Furthermore, the aforementioned structures all use micro linear guides as motion guides to guide the nozzle up and down. The placement accuracy of this type of structure is not only affected by the accuracy of the motion axis, but also by the clearance interference of the micro linear guides, resulting in unsatisfactory placement accuracy. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a placement head assembly with a rotation center alignment based on direct drive technology, wherein the rotation of the placement head is driven by a direct drive rotating platform, and the deformation displacement of the elastic part connected to the placement head is detected by a displacement sensor and fed back to the controller, and only a suction nozzle mounting seat and a suction nozzle assembly are provided on the elastic part, thereby reducing the load pressure of the elastic part to the greatest extent, thereby being able to control the placement pressure more accurately.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A placement head assembly for rotation center alignment based on direct drive technology comprises a shell, a direct drive rotating platform is arranged in the shell, and a force control placement head is connected to the direct drive rotating platform; the force control placement head comprises a first connecting block, a nozzle mounting seat and at least one elastic member, wherein the first connecting block and the nozzle mounting seat are connected at opposite ends of the elastic member; the first connecting block is fixedly connected to the direct drive rotating platform; a nozzle assembly is arranged below the nozzle mounting seat, and a sensing block is arranged at the position of the nozzle mounting seat protruding from the elastic member, and a displacement sensor fixedly connected to the direct drive rotating platform is arranged directly above the sensing block, and the displacement sensor is electrically connected to the controller of the placement force control system.

[0009] The aforementioned placement head assembly for rotation center alignment based on direct drive technology is characterized in that: the force-controlled placement head includes two elastic parts of the same shape, and the elastic parts are metal springs, and the first connecting block and the suction nozzle mounting seat are clamped between the two elastic parts of the same shape, and the upper surface of the upper elastic part, the lower surface of the lower elastic part, and the connection between the first connecting block and the suction nozzle mounting seat are fixedly connected with gaskets.

[0010] The aforementioned placement head assembly for rotation center alignment based on direct drive technology is characterized in that a limit block located on the nozzle mounting seat is provided below the sensing block, and a support block connected to the direct drive rotating platform and in contact with the limit block is provided directly below the limit block.

[0011] The aforementioned placement head assembly for rotation center alignment based on direct drive technology is characterized in that: a second connecting block is fixedly connected to the direct drive rotating platform, a turntable is fixedly connected to the second connecting block, a third connecting block is provided on the turntable, the support block is provided on the third connecting block, and the support block can be adjusted up and down relative to the third connecting block.

[0012] The aforementioned placement head assembly for rotation center alignment based on direct drive technology is characterized in that: the elastic member is a square frame structure, the suction nozzle mounting seat is located in the elastic member frame and is provided with a through hole, the upper end of the through hole is sealed by a lens, the top of the suction nozzle assembly is provided with a suction hole matching the through hole, the suction nozzle mounting seat is provided with a first vacuum suction hole connected to the through hole, a cover plate connected to the outer shell is provided above the direct drive rotating platform, the direct drive rotating platform is a hollow annular structure, and the cover plate is provided with an observation hole corresponding to the position of the lens.

[0013] The aforementioned placement head assembly based on direct drive technology and rotation center alignment is characterized in that: the top of the suction nozzle assembly is consistent with the shape and size of the bottom of the suction nozzle mounting seat, and a cavity is provided outside the suction hole, and the bottom of the suction nozzle mounting seat is provided with a second vacuum suction hole that can be connected to the cavity.

[0014] The aforementioned placement head assembly based on direct drive technology for rotation center alignment is characterized in that adjustment bolts for adjusting the horizontality of the direct drive rotation platform relative to the housing are respectively provided at the diagonals of the direct drive rotation platform.

[0015] The aforementioned placement head assembly based on direct drive technology and rotation center alignment is characterized in that: the displacement sensor is fixedly connected to the direct drive rotation platform through a fourth connecting block, and a waist-shaped groove is provided on the connecting surface of the fourth connecting block.

[0016] The aforementioned placement head assembly based on direct drive technology for rotation center alignment is characterized in that an angle position feedback scale structure for detecting the rotation angle thereof is provided above the direct drive rotation platform.

[0017] The beneficial effects of the present invention are:

[0018] 1. By using a direct-drive rotary platform to drive the rotation of the placement head assembly, a sensor is used to detect the deformation of the elastic member connected to the nozzle mounting base during placement. Each tiny displacement of the nozzle is detected in real time, thereby effectively controlling the placement pressure. The elastic force of the elastic member can be used to stably and accurately return to the original position each time. This drive structure fundamentally solves the problem of reduced accuracy caused by mechanical clearance introduced by the linear guide rail in traditional placement heads.

[0019] 2. The nozzle mount is clamped and fixed by two elastic members of the same shape. When the chip on the nozzle assembly connected to the nozzle mount is subjected to placement pressure, one end of the two elastic members is fixed, thereby ensuring that the nozzle mount remains horizontal and moves up and down under the clamping of the elastic members. This also ensures that the chip on the nozzle assembly always remains horizontal during the placement process, ensuring balanced placement pressure.

[0020] 3. Only the nozzle mounting base and nozzle assembly are fixedly connected to the elastic part, which minimizes the load on the elastic part, making the mobile end of the force control system extremely lightweight and improving the response speed of the force control;

[0021] 4. By using a direct-drive rotary platform to drive the rotation of the placement head assembly, combined with the observation lens on the nozzle mount, it is easy to observe the surface features of the adsorbed chip from inside the nozzle assembly, and the nozzle assembly is adsorbed on the nozzle mount using vacuum air to ensure that the observation window of the nozzle mount and the nozzle assembly remain relatively stationary. At the same time, the placement head is mounted under the direct-drive rotary platform to align the nozzle center with the rotation center to ensure that the chip does not exceed the field of view of the visual system when rotating; and a high-precision angular position feedback scale structure is used to feedback the rotation state of the direct-drive rotary platform to achieve high-precision rotation and visual real-time alignment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a front view of a placement head assembly with rotation center alignment based on direct drive technology according to the present invention;

[0023] Figure 2 It is a front view of a placement head assembly based on direct drive technology and rotation center alignment of the present invention;

[0024] Figure 3 yes Figure 2 AA section view in;

[0025] Figure 4 yes Figure 3 A is an enlarged schematic diagram;

[0026] Figure 5 This is a schematic diagram of the structure of a placement head assembly with a rotation center aligned based on direct drive technology after a cover plate is hidden in the present invention;

[0027] Figure 6 This is a schematic diagram of the disassembly of a placement head assembly with a rotation center aligned based on direct drive technology after a cover plate is hidden;

[0028] Figure 7 It is a structural schematic diagram of the mounting assembly portion of a mounting head assembly with a rotation center alignment based on direct drive technology of the present invention;

[0029] Figure 8 This is a front view of the force control portion of the placement component portion of a placement head assembly with rotation center alignment based on direct drive technology of the present invention;

[0030] Figure 9 It is a bottom view of the force control portion of the placement component portion of a placement head assembly with rotation center alignment based on direct drive technology of the present invention;

[0031] Figure 10 This is a front view of a nozzle assembly of a placement head assembly with a rotation center aligned based on direct drive technology of the present invention;

[0032] In the figure,

[0033] 10. Shell;

[0034] 20. Direct drive rotating platform; 21. Adjusting bolt;

[0035] 30. Force control placement head; 31. First connecting block; 32. Elastic member; 33. Nozzle mounting base; 331. Sensing block; 332. Limit block; 333. Second vacuum suction hole; 34. Nozzle assembly; 36. Lens; 37. Second connecting block; 38. Turntable; 39. Third connecting block; 391. Support block;

[0036] 40. Angle position feedback scale structure;

[0037] 50, cover plate; 51, observation hole;

[0038] 60. Displacement sensor; 61. Fourth connecting block. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings.

[0040] like Figures 1-10 As shown, a placement head assembly for rotation center alignment based on direct drive technology includes a shell 10, a direct drive rotating platform 20 is arranged in the shell 10, and a force control placement head 30 is connected to the direct drive rotating platform 20; the force control placement head 30 includes a first connecting block 31, a nozzle mounting seat 33 and at least one elastic member 32, wherein the first connecting block 31 and the nozzle mounting seat 33 are connected at opposite ends of the elastic member 32; the first connecting block 31 is fixedly connected to the direct drive rotating platform 20; a nozzle assembly 34 is provided below the nozzle mounting seat 33, and a sensing block 331 is provided at the position where the nozzle mounting seat 33 protrudes from the elastic member 32, and a displacement sensor 60 fixedly connected to the direct drive rotating platform 20 is provided directly above the sensing block 331, and the displacement sensor 60 is electrically connected to the controller of the placement force control system.

[0041] During the chip mounting process, the movement of the entire mounting head assembly is driven by a three-axis drive mechanism, and the rotation of the suction nozzle assembly 34 is driven by a direct-drive rotary platform 20 set in the mounting head assembly. After the suction nozzle assembly 34 sucks the chip to be mounted, it is driven by the three-axis drive mechanism to move it to the set position, and then the angle is adjusted by the direct-drive rotary platform 20. Then, the three-axis drive mechanism drives the entire mounting head assembly to be pressed down. During the downward pressing process, the elastic part 32 on the suction nozzle mounting seat 33 is deformed, thereby generating a small displacement. Then, the displacement sensor 60 is used to detect the displacement of the sensing block 331, and the real-time feedback is fed back to the mounting control system, thereby controlling the three-axis drive mechanism to ensure that the mounting pressure is accurately controlled.

[0042] The present invention drives the direct-drive rotating platform 20 by adopting a direct-drive rotating platform 20, and at the same time only connects the suction nozzle mounting seat 33 and the suction nozzle assembly 34 on the elastic member 32, thereby reducing other loads such as the rotating shaft, linear rail, and motor, and reducing the load on the elastic member 32 to the greatest extent, which can make the mobile end of the force control system extremely lightweight and improve the response speed of the force control.

[0043] In this embodiment, the force-controlled placement head 30 includes two elastic members 32 of the same shape, which are metal springs, and the first connecting block 31 and the nozzle mounting seat 33 are clamped between the two elastic members 32 of the same shape, and the upper surface of the upper elastic member 32 and the lower surface of the lower elastic member 32 are fixedly connected with the first connecting block 31 and the nozzle mounting seat 33 at the connection point with gaskets.

[0044] The nozzle mounting base 33 is clamped and fixed by using two elastic members 32 of the same shape, and the other end of the elastic member 32 is fixedly connected to the direct-drive rotating platform 20 after clamping the first connecting block 31, and always maintains a horizontal state. It should be noted that the thickness of the first connecting block 31 and the nozzle mounting base 33 clamped between the two elastic members 32 of the same shape are consistent. In the initial state, the upper and lower elastic members 32 do not undergo any deformation. When the chip on the nozzle assembly 34 connected to the lower part of the nozzle mounting base 33 is subjected to mounting pressure, the two elastic members 32 are in a state of being pressed together. One end of the elastic member 32 is completely fixed, thereby ensuring that the nozzle mounting seat 33 can only move up and down in a horizontal state when clamped by the upper and lower elastic members 32 (if the nozzle mounting seat 33 is tilted, the nozzle mounting seat 33 needs to move relative to at least one elastic member 32 or the elastic member 32 is stretched, but in this embodiment, the nozzle mounting seat 33 is fixedly connected to the elastic member 32, and the elastic member 32 is made of metal and will not be stretched under slight pressure), thereby ensuring that the chip on the nozzle assembly always remains horizontal during the mounting process, ensuring balanced mounting pressure.

[0045] A limit block 332 located on the nozzle mounting base 33 is provided below the sensing block 331. A support block 391 connected to the direct-drive rotating platform 20 and in contact with the limit block 332 is provided directly below the limit block 332. Specifically, a second connecting block 37 is fixedly connected to the direct-drive rotating platform 20, a turntable 38 is fixedly connected to the second connecting block 37, a third connecting block 39 is provided on the turntable 38, and the support block 391 is provided on the third connecting block 39, and the support block 391 can be adjusted up and down relative to the third connecting block 39. By connecting the second connecting block 37, the turntable 38 and the third connecting block 39, the support block 391 set on the third connecting block 39 is rotated synchronously with the direct-drive rotating platform 20. Since the first connecting block 31 and the suction nozzle mounting seat 33 also rotate synchronously with the direct-drive rotating platform 20, the support block 391 and the limit block 332 are relatively stationary. By adjusting the position of the support block 391, it is ensured that in the initial state, under the action of the support block 391 and the limit block 332, the elastic member 32 is not subjected to any force and does not undergo any deformation, which is convenient for subsequent displacement detection and rapid reset.

[0046] The elastic member 32 is a square frame structure. The suction nozzle mounting seat 33 is located in the elastic member 32 square frame and is provided with a through hole. The upper end of the through hole is sealed by a lens 36. The top of the suction nozzle assembly 34 is provided with a suction hole 341 matched with the through hole. The suction nozzle mounting seat 33 is provided with a first vacuum suction hole connected to the through hole. A cover plate 50 connected to the housing 10 is provided above the direct drive rotary platform 20. The direct drive rotary platform 20 is a hollow annular structure. The cover plate 50 is provided with an observation hole 51 corresponding to the position of the lens 36. The visual inspection system above the mounting head assembly can observe the surface of the chip sucked by the suction nozzle assembly 34 through the observation hole 51 and the lens 36. When it is determined that angle compensation is required, the direct drive rotary platform 20 is rotated, and the angle position feedback scale structure 40 provided above the direct drive rotary platform (20) is used to accurately control the rotation angle.

[0047] The top of the nozzle assembly 34 is consistent in shape and size with the bottom of the nozzle mounting base 33. A cavity 342 is provided outside the suction hole 341, and a second vacuum suction hole 333 is provided at the bottom of the nozzle mounting base 33, which is connected to the cavity 342. By drawing air through the second vacuum suction hole 333, the nozzle assembly 34 can be quickly connected to the bottom of the nozzle mounting base 33 by vacuum suction.

[0048] Therefore, by adopting the direct-drive rotary platform 20 to drive the rotation of the placement head assembly, combined with the observation lens 36 on the nozzle mounting seat 33, it is easy to observe the surface features of the adsorbed chip from the inside of the nozzle assembly 34, and the nozzle assembly is adsorbed on the nozzle mounting seat using vacuum air to ensure that the observation window of the nozzle mounting seat and the nozzle assembly remain relatively stationary. At the same time, the placement head is mounted under the direct-drive rotary platform to align the nozzle center with the rotation center to ensure that the chip does not exceed the field of view of the visual system when rotating; and a high-precision angular position feedback scale structure is used to feedback the rotation state of the direct-drive rotary platform to achieve high-precision rotation and visual real-time alignment.

[0049] The diagonal portions of the direct-drive rotary platform 20 are provided with adjusting bolts 21 for adjusting the levelness thereof relative to the housing 10. In the initial state, the levelness of the direct-drive rotary platform 20 can be adjusted by adjusting the bolts 21, thereby adjusting the levelness of the nozzle assembly 34.

[0050] The displacement sensor 60 is fixedly connected to the direct-drive rotating platform 20 via a fourth connecting block 61 to achieve synchronous rotation of the two, and a waist-shaped groove is provided on the connecting surface of the fourth connecting block 61 to facilitate adjustment of the installation height during assembly.

[0051] A method for mounting a mounting head assembly based on direct drive technology and rotary center alignment comprises the following steps:

[0052] (1) The placement head assembly absorbs the chip to be placed and moves to the top of the placement position under the drive of the three-axis drive mechanism;

[0053] (2) After the position of the chip to be mounted is detected by the visual inspection mechanism, the angle is adjusted using the direct drive rotary platform;

[0054] (3) Control the placement head assembly to move down at high speed to the pre-pressing position and then slowly press down, use the displacement sensor to detect the displacement of the elastic part, and feed the displacement signal back to the controller for real-time monitoring until the monitored displacement reaches the preset value, stop moving, and perform pressure holding treatment;

[0055] (4) Control the placement head assembly to release the chip and reset it.

[0056] Among them, the displacement sensor used in step (3) is an eddy current sensor. When the displacement of the elastic member changes, the current signal of the eddy current sensor will also change accordingly. When processing the current signal, the step command current signal is smoothed by a second-order lag filter, and the PI controller realizes the tracking of the filtered command current. On this basis, an integral saturator is added to reduce the overshoot of the actual current, and a variable proportional gain control is added to reduce the current jitter in the pressure holding stage.

[0057] The specific implementation process is:

[0058] A second-order lag filter is used to smooth the step command current. The transfer function of the second-order lag filter is:

[0059] ;

[0060] in, is the time constant, is the damping ratio.

[0061] Performing Laplace inverse transform and time domain discretization on the transfer function, we get the difference equation:

[0062] ;

[0063] is a discrete time variable, , represents the sampling time sequence number of the command current. 、 When the discrete time variable in is negative, take the initial value 、 ;

[0064] in, is the filtered command current, is the command current before filtering, , , , , .

[0065] Defining Current Error for:

[0066] ;

[0067] in, is the actual current.

[0068] The current loop adopts PI control, and the output of the PI controller is :

[0069] ;

[0070] in, is the proportional gain coefficient, is the integral gain coefficient.

[0071] In PI control, the integrator accumulates the error to eliminate the steady-state error, but if the integral term is too large, it will lead to overshoot. Therefore, an anti-saturation integrator is introduced to reduce the overshoot:

[0072] ;

[0073] in, is the output limiter, is the output after the limiter, is the anti-saturation coefficient.

[0074] When the output is saturated, the anti-saturation integrator can significantly weaken the integral accumulation, and the position error can be quickly desaturated after the reverse, thereby reducing the overshoot.

[0075] During the pressure holding phase, the command current remains unchanged, but the actual current often has static jitter caused by noise. This may amplify high-frequency noise and exacerbate static jitter, so variable proportional gain control is introduced. When the current error reaches a certain range, it is reduced. , consider the case where the PI controller output is not saturated.

[0076] ;

[0077] and is the proportional gain coefficient at different stages ( ), It is the current error threshold of variable proportional gain control.

[0078] In summary, the present invention is a placement head assembly with a rotation center aligned based on direct drive technology, which drives the rotation of the placement head through a direct drive rotating platform, uses a displacement sensor to detect the deformation displacement of the elastic part connected to the placement head and feeds back to the controller, and only a suction nozzle mounting seat and a suction nozzle assembly are provided on the elastic part, thereby reducing the load pressure of the elastic part to the greatest extent, thereby being able to control the placement pressure more accurately.

[0079] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A placement head assembly based on direct drive technology for rotary center alignment, characterized by: It comprises a housing (10), wherein a direct-drive rotating platform (20) is provided in the housing (10), and a force-controlled mounting head (30) is connected to the direct-drive rotating platform (20); The force-controlled placement head (30) comprises a first connecting block (31), a nozzle mounting seat (33) and at least one elastic member (32), wherein the first connecting block (31) and the nozzle mounting seat (33) are connected at opposite ends of the elastic member (32); The first connecting block (31) is fixedly connected to the direct-drive rotating platform (20); A nozzle assembly (34) is provided below the nozzle mounting seat (33), and a sensing block (331) is provided at a position of the nozzle mounting seat (33) protruding from the elastic member (32), and a displacement sensor (60) fixedly connected to the direct-drive rotary platform (20) is provided directly above the sensing block (331), and the displacement sensor (60) is electrically connected to a controller of a placement force control system; The force-controlled placement head (30) comprises two elastic members (32) of identical shape, and the elastic members (32) are metal springs. The first connecting block (31) and the nozzle mounting seat (33) are clamped between the two elastic members (32) of identical shape, and gaskets are provided at the connection between the upper surface of the upper elastic member (32), the lower surface of the lower elastic member (32), the first connecting block (31) and the nozzle mounting seat (33) for fixed connection.

2. A placement head assembly based on direct drive technology and rotation center alignment according to claim 1, characterized in that: A limit block (332) located on the nozzle mounting seat (33) is provided below the sensing block (331), and a support block (391) connected to the direct-drive rotating platform (20) and in contact with the limit block (332) is provided directly below the limit block (332).

3. A placement head assembly based on direct drive technology and rotation center alignment according to claim 2, characterized in that: A second connecting block (37) is fixedly connected to the direct-drive rotating platform (20), a turntable (38) is fixedly connected to the second connecting block (37), a third connecting block (39) is provided on the turntable (38), the support block (391) is provided on the third connecting block (39), and the support block (391) can be adjusted up and down relative to the third connecting block (39).

4. The placement head assembly based on direct drive technology and rotation center alignment according to claim 1, characterized in that: The elastic member (32) is a square frame structure, the suction nozzle mounting seat (33) is located in the elastic member (32) square frame and is provided with a through hole, the upper end of the through hole is sealed by a lens (36), the top of the suction nozzle assembly (34) is provided with a suction hole (341) matched with the through hole, the suction nozzle mounting seat (33) is provided with a first vacuum suction hole connected to the through hole, a cover plate (50) connected to the shell (10) is provided above the direct-drive rotating platform (20), the direct-drive rotating platform (20) is a hollow annular structure, and an observation hole (51) corresponding to the position of the lens (36) is provided on the cover plate (50).

5. The placement head assembly based on direct drive technology and rotation center alignment according to claim 4, characterized in that: The top of the suction nozzle assembly (34) is consistent with the shape and size of the bottom of the suction nozzle mounting seat (33), and a cavity (342) is provided outside the suction hole (341), and the bottom of the suction nozzle mounting seat (33) is provided with a second vacuum suction hole (333) that can be communicated with the cavity (342).

6. A placement head assembly based on direct drive technology and rotation center alignment according to claim 5, characterized in that: Adjustment bolts (21) for adjusting the horizontality of the direct-drive rotary platform (20) relative to the housing (10) are respectively provided at the diagonal positions of the direct-drive rotary platform (20).

7. The placement head assembly based on direct drive technology and rotation center alignment according to claim 1, characterized in that: The displacement sensor (60) is fixedly connected to the direct-drive rotary platform (20) via a fourth connecting block (61), and a waist-shaped groove is provided on the connecting surface of the fourth connecting block (61).

8. The placement head assembly based on direct drive technology and rotation center alignment according to claim 1, characterized in that: An angular position feedback scale structure (40) for detecting the rotation angle of the direct-drive rotary platform (20) is provided above the direct-drive rotary platform (20).

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