Micro LED mass transfer device

Abstract

The invention discloses a micro LED mass transfer device which comprises an upper carrying table arranged above an X-axis and Y-axis displacement platform. A leveling assembly is arranged under the upper carrying table. The leveling assembly comprises a connecting disc longitudinally connected to the XY-axis displacement platform in a sliding mode, a downloading table arranged over the connecting disc, three air springs longitudinally arranged at the upper end of the connecting disc and evenly distributed in the circumferential direction of the connecting disc, and a locking device arranged in the connecting disc. Wherein the upper end of the gas spring abuts against the lower end of the lower carrier; and the locking device can selectively lock the extension length of the gas spring. The device has the beneficial effects that the parallelism of the upper and lower carrying tables is adjusted, so that the stability of the MicroLED chip in the transfer process is improved; and no complex sensor is needed, so that no electronic error exists, the control logic is simplified, and the manufacturing cost is reduced. The height and the angle of the downloading table are automatically adjusted, the manual participation amount is reduced, and therefore the machining precision is improved.

Description

Technical Field

[0001] This invention belongs to the field of MicroLED technology, and particularly relates to a MicroLED mass transfer device. Background Technology

[0002] Micro-LED, also known as micro-light-emitting diode, refers to a high-density integrated LED array. The distance between LED pixels in the array can reach the 10µm level, and each LED pixel is self-emissive. Compared with traditional display technologies, Micro-LED has unique advantages such as higher resolution, lower power consumption, higher brightness, and faster response speed. Because of these advantages, Micro-LED technology is hailed as the next-generation display technology and has been highly sought after by numerous companies worldwide in the past decade, representing an important future direction for display technology. After fabrication, millions of Micro-LEDs need to be transferred from the wafer to the driving circuit substrate using mass transfer technology. Due to the small size of Micro-LED chips and the high precision required for positioning, the success rate of chip transfer is extremely low. How to successfully transfer Micro-LED chips to the electrodes of the corresponding display driving circuit substrate has become a major challenge in the mass transfer and industrialization process of Micro-LED.

[0003] Chinese patent document CN115050858A discloses a pneumatic mass transfer device for Mini / Micro LED chips, which mainly consists of a chip stage system, a substrate stage system, and a pneumatic vision system. The chip stage system mainly includes: a marble base, a support, an outer guide rail, a linear motor, a chip linear movement component, a longitudinal grating ruler, a longitudinal grating ruler reading head, a chip rotation adjustment component, and a chip carrier board. The substrate stage system mainly includes: a lower grating ruler, a lower grating ruler reading head, an inner guide rail, an inner motor, a substrate longitudinal movement component, and a substrate lateral movement component. The pneumatic vision system mainly includes: a support beam, an upper guide rail, an upper linear motor, an upper lateral movement component, a pressure regulating valve, a high-frequency solenoid valve, a lateral grating ruler reading head, a lateral grating ruler, a fixed base plate, a fixed base, an industrial CCD camera, and an air nozzle.

[0004] In the above scheme, because the size of MicroLEDs and the spacing between adjacent ones are very small, when the glass plates placed on the two platforms (chip platform and substrate platform) are not parallel due to assembly or repeated positioning errors and the influence of external working conditions, the MicroLED chips will tilt or misalign during the transfer process. The degree of tilt and the tilt or misalignment of the MicroLED chips are difficult to observe with the naked eye and manually adjust, which will affect the display effect and lifespan of the MicroLED display device. Summary of the Invention

[0005] In order to overcome the problem that the MicroLED chip will tilt or misalign during the transfer process due to the non-parallelism between the two platforms in the prior art, one object of the present invention is to provide a MicroLED mass transfer device, which sets one platform in a movable form, presses the glass plates on the two platforms together and then locks the movable platform, so that the two platforms will remain parallel even after they are separated.

[0006] To achieve the above objectives, the present invention employs the following technical solution: a MicroLED mass transfer device, comprising an upper stage disposed above an XY-axis displacement platform and a laser engraving head disposed above the upper stage; a leveling assembly disposed directly below the upper stage; the leveling assembly comprising a connecting plate longitudinally slidably connected to the XY-axis displacement platform, a downloading stage disposed directly above the connecting plate, three gas springs longitudinally disposed on the upper end of the connecting plate and evenly distributed along the circumference of the connecting plate, and a locking device disposed within the connecting plate; wherein, the upper end of the gas spring abuts against the lower end of the downloading stage; the locking device selectively locks the extension length of the gas spring.

[0007] The three gas springs push the glass on the download platform upwards until it abuts against the glass on the upper loading platform. The gas springs, which are initially subjected to contact pressure, will partially retract to achieve pneumatic self-leveling. This eliminates the need for complex sensors, thus avoiding electronic errors and simplifying the control logic and reducing manufacturing costs.

[0008] Specifically, the upper end of the connecting plate is slidably connected with three support rods evenly distributed along the circumference of the connecting plate; the lower end of the download platform is provided with three conical concave surfaces that are respectively opposite to the support rods; the upper end of the support rod is hemispherical and located within the concave surface of the cone; a spring is provided between the support rod and the download platform.

[0009] Specifically, the locking device consists of three locking rods that are laterally slidably connected within the connecting disc; the locking rods can be selectively engaged with the support rod.

[0010] Optionally, the connecting plate has three radially arranged vent chambers that are respectively slidably and sealingly connected to the locking rod; the three vent chambers are interconnected.

[0011] When all three gas springs are compressed, the support rod is locked by the locking rod, so that the download platform and the connecting plate are fixed relative to each other. After the download platform returns to its original position, the glass on the download platform and the glass on the upper loading platform remain horizontal.

[0012] Preferably, a through hole is formed in the center of the upper platform; a pressure plate frame for fixing the glass plate is provided at the lower end of the upper platform; a lower vision module is provided on the XY axis displacement platform below the pressure plate frame; and an upper vision module is provided on the XY axis displacement platform directly above the through hole.

[0013] Since MicroLED chips come in various styles and forms, different vision modules are selected depending on the type of processing. Specifically, chips with higher transparency use the upper vision module, which allows them to better see through transparent objects and capture details inside the objects; chips with lower transparency use the lower vision module, which allows them to better reflect light from the surface of objects, thereby obtaining clearer images.

[0014] Preferably, the upper end of the download platform is formed with three threaded through holes that pass through the download platform and are respectively opposite to the gas spring; each of the threaded through holes is detachably connected to a stud; the length of the stud is less than the depth of the threaded through hole; the upper end of the gas spring is hemispherical; the upper end of the gas spring is located in the threaded through hole and abuts against the lower end of the stud.

[0015] Furthermore, a displacement assembly is provided at the upper end of the XY-axis displacement platform; the displacement assembly includes a support tube fixedly connected to the lower end of the connecting plate, a lifting motor provided on the XY-axis displacement platform for driving the support tube to slide longitudinally, and a rotary motor provided on the XY-axis displacement platform for driving the support tube to rotate circumferentially.

[0016] The loading stage rotates to adjust the orientation of the chip array on which the MicroLED chip stamp is mounted; the download stage rotates to adjust the orientation of the receiving substrate on the download stage, ensuring that the orientation of the chip array is the same as the displacement direction of the XY axis displacement platform, eliminating loading errors and increasing transfer accuracy.

[0017] Specifically, the displacement assembly includes a mounting base disposed on the XY-axis displacement platform and a rotating ring rotatably connected to the upper end of the mounting base and driven by the rotary motor; the support tube is slidably connected in the axial direction within the rotating ring; the outer wall of the support tube is formed with a longitudinally arranged groove; and the inner wall of the rotating ring is formed with a longitudinally arranged protrusion that is slidably connected to the groove.

[0018] Specifically, a longitudinal lead screw coaxially arranged with the support tube is rotatably connected to the mounting base; a lead screw nut that is slidably connected to the longitudinal lead screw is driven by the longitudinal lead screw; the lead screw nut abuts against the lower end of the support tube; and the longitudinal lead screw is driven by the lifting motor.

[0019] Preferably, the displacement assembly includes a transmission block that is laterally slidably connected to the mounting base and is connected to the rotating ring drive, and a transverse lead screw that is rotatably connected to the mounting base and is driven by the transmission block; the rotary motor is driven by the transverse lead screw.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The present invention can adjust the parallelism of the upper and lower platforms before image acquisition of the MicroLED chip, thereby increasing the stability of the MicroLED chip transfer process and preventing tilting or misalignment.

[0022] 2. Three gas springs press against the glass on the download platform and fit it tightly against the glass on the upper loading platform. The gas springs that are first subjected to the pressure of the fit will partially retract to achieve pneumatic self-leveling. There is no need for complex sensors, so there is no electronic error, which simplifies the control logic and reduces manufacturing costs.

[0023] 3. This invention selects either an upper vision module or a lower vision module as the acquisition unit based on different types and varieties of MicroLED chips, and automatically adjusts the height and angle of the download stage according to program feedback, reducing the amount of manual intervention and thus improving processing accuracy;

[0024] 4. This invention relies on an upper vision module or a lower vision module to automatically adjust the chip array direction of the MicroLED chip stamp on the loading stage and the direction of the receiving substrate on the download stage, ensuring that the MicroLED chip array direction and the displacement direction of the XY axis displacement platform are the same, eliminating loading errors and increasing transfer accuracy. Attached Figure Description

[0025] Figure 1 This is a front structural diagram of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the back side of the present invention;

[0027] Figure 3 This is a schematic diagram of the assembly of the displacement component and the leveling component of the present invention;

[0028] Figure 4 , Figure 5 This is an exploded view of the displacement component and leveling component of the present invention;

[0029] Figure 6 For the present invention Figure 5 Enlarged diagram of section A in the middle;

[0030] Figure 7 This is a cross-sectional schematic diagram of the displacement component and leveling component of the present invention.

[0031] In the diagram: 1. XY axis displacement platform; 2. Displacement assembly; 21. Mounting base; 22. Rotary ring; 23. Support tube; 231. Groove; 24. Rotary motor; 25. Longitudinal lead screw; 26. Lifting motor; 27. Lead screw nut; 3. Leveling assembly; 31. Connecting plate; 311. Vent chamber; 32. Download platform; 321. Light blocking plate; 322. Threaded through hole; 33. Suction cup; 34. Gas spring; 35. Support rod; 36. Photoelectric switch; 37. Limit screw; 38. Locking rod; 39. Stud; 4. Upper vision module; 5. Laser engraving head; 6. Upper platform; 61. Through hole; 7. Lower vision module. Detailed Implementation

[0032] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0033] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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. They should not be construed as limiting the specific protection scope of this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, terms such as "set" and "install" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] See Figures 1 to 7A MicroLED mass transfer device includes a displacement component 2 disposed on the upper end of an XY-axis displacement platform 1, a leveling component 3 disposed on the upper end of the displacement component 2, an upper stage 6 disposed on the XY-axis displacement platform 1 and located directly above the leveling component 3, and a laser engraving head 5 disposed on the upper end of the XY-axis displacement platform and located directly above the upper stage 6; the XY-axis displacement platform 1 includes a base and a motion platform disposed on the base; an upper vision module 4 is disposed on the base and located directly above the upper stage 6; a lower vision module 7 is disposed on the motion platform and located directly below the upper stage 6.

[0037] The displacement component 2 includes a mounting base 21 disposed on the motion platform, a rotating ring 22 rotatably connected to the upper end of the mounting base 21, and a support tube 23 longitudinally slidably connected within the rotating ring 22; the outer wall of the support tube 23 is formed with a longitudinally arranged groove 231; the inner wall of the rotating ring 22 is formed with a longitudinally arranged protrusion that is slidably connected to the groove 231.

[0038] The displacement assembly 2 includes a longitudinal lead screw 25 rotatably connected to the mounting base 21, a lead screw nut 27 longitudinally slidably connected to the mounting base 21 and drivingly connected to the longitudinal lead screw 25, and a lifting motor 26 fixedly connected to the mounting base 21 and drivingly connected to the longitudinal lead screw 25; the lead screw nut 27 is longitudinally slidably connected to the mounting base 21, and the lead screw nut 27 can only slide longitudinally; the upper end of the lead screw nut 27 abuts against the lower end of the support tube 23.

[0039] The displacement component 2 includes a transmission block that is laterally slidably connected to the mounting base 21 and is pulsatorically connected to the rotating ring 22, a transverse lead screw that is rotatably connected to the mounting base 21 and is pulsatorically connected to the transmission block, and a rotary motor 24 that is fixedly connected to the mounting base 21 and is pulsatorically connected to the transverse lead screw. The transverse lead screw can only drive the rotating ring 22 to rotate slightly by a large rotation, thereby improving the position adjustment accuracy of the leveling component 3.

[0040] The leveling assembly 3 includes a connecting plate 31 fixedly connected to the upper end of the support tube 23, a download platform 32 disposed directly above the connecting plate 31, three gas springs 34 longitudinally disposed on the upper end of the connecting plate 31 and evenly distributed along the circumference of the connecting plate 31, and a locking device disposed within the connecting plate 31; the upper end of the gas spring 34 abuts against the lower end of the download platform 32; the locking device can selectively lock the extension length of the gas spring 34; a suction cup 33 is disposed at the center of the upper end of the download platform 32. A light-blocking plate 321 is fixedly connected to the outer periphery of the download platform 32; a photoelectric switch 36 is fixedly connected to the connecting plate 31; the light-blocking plate 321 slides downward to actuate the photoelectric switch 36.

[0041] The upper end of the connecting plate 31 is longitudinally slidably connected to three support rods 35 evenly distributed along the circumference of the connecting plate 31; the lower end of the download platform 32 is provided with three conical concave surfaces respectively facing the support rods 35; the upper end of the support rod 35 is hemispherical and located within the concave surface of the cone; a spring 351 is provided between the support rod 35 and the download platform 32; the upper end of the connecting plate 31 is fixedly connected to a limiting screw 37 for limiting the sliding distance of the download platform 32.

[0042] The locking device consists of three locking rods 38 that are laterally slidably connected within the connecting plate 31; the locking rods 38 can be selectively engaged with the support rod 35; the connecting plate 31 has three radially arranged vent chambers 311 that are respectively slidably and sealingly connected with the locking rods 38; the three vent chambers 311 are interconnected.

[0043] The upper end of the download platform 32 has three threaded through holes 322 that pass through the download platform 32 and are respectively opposite to the gas spring 34; each of the threaded through holes 322 is detachably connected to a stud 39; the length of the stud 39 is less than the depth of the threaded through hole 322; the upper end of the gas spring 34 is hemispherical; the upper end of the gas spring 34 is located in the threaded through hole 322 and abuts against the lower end of the stud 39; to prevent the lifting position of the gas spring 34 from slipping.

[0044] The upper platform 6 is slidably connected to the motion platform along the X-axis. The upper platform 6 is an XXY precision alignment platform, capable of horizontal movement in the XY direction and horizontal rotation with the rotation axis longitudinally. It has a through hole 61 in its center for easy observation by the vision module. The lower end of the upper platform 6 is horizontal. A pressure plate frame for fixing the glass plate is provided at the lower end of the upper platform 6. Since MicroLED chips have various styles and forms, different vision modules are selected according to the processing type. Specifically, chips with higher transparency are selected using the upper vision module 4; this helps the device to more accurately identify and process the chips during grasping and transfer. Chips with lower transparency are selected using the lower vision module 7; this helps the device achieve more precise alignment and placement when placing the chip at the target position. It should be noted that chips with higher transparency require higher performance from the acquisition device; while chips with lower transparency require more precise alignment and placement. In practical applications, the vision modules need to be adjusted and optimized according to specific needs and scenarios to achieve the best acquisition effect.

[0045] Usage: The operator places a 10mm*10mm flat glass (hereinafter referred to as the lower glass plate) on the suction cup 33, turns on the "suction plate" button, and the suction cup 33 sucks in air to lock the lower glass plate. At the same time, a 13mm*13mm flat glass (hereinafter referred to as the upper glass plate) is placed below the through hole 61, and the pressure plate frame is operated to fix the upper glass plate. At this time, three gas springs 34 lift the lowering platform 32.

[0046] Next, pressing the "Up" button activates the controller, which in turn activates the lifting motor 26, causing the longitudinal lead screw 25 to rotate forward. This forward rotation of the lead screw 25 moves the lead screw nut 27 upward, thus moving the download platform 32 and the lower glass plate upward. Once the lower glass plate is in contact with the upper glass plate, the first gas spring 34 to come into contact with it will be compressed. This means the three gas springs 34 can adjust their extension length based on the uniformity of the contact pressure. Under this pressure, the download platform 32 slides downward relative to the connecting plate 31. This downward sliding of the download platform 32 causes the light-blocking plate 321 to slide downward until it triggers the photoelectric switch 36. Based on the feedback from the photoelectric switch 36, the controller stops the lifting motor 26 and simultaneously inflates the ventilation chamber 311 via the air pump. This causes the locking rod 38 to slide outward until it abuts against the support rod 35, restricting the relative sliding between the support rod 35 and the connecting plate 31.

[0047] Next, press the "Lower" button. The lifting motor 26 drives the longitudinal lead screw 25 to rotate in the opposite direction, causing the download platform 32 to slide down to its original position. Since the upper glass plate and the lower glass plate are parallel to each other when they are pressed together, the support rod 35 is locked. After the download platform 32 slides down and the upper glass plate and the lower glass plate separate, they still remain parallel to each other, thus completing the leveling.

[0048] Subsequently, the pressure plate frame is opened, the upper glass plate is removed, and a stamp with the Micro-LED markings is affixed, facing downwards. It is then returned to its original position, and the pressure plate frame is closed. Simultaneously, the receiving substrate is placed on the lower glass plate, and the "gap" and "sum of the thickness of the stamp, receiving substrate, and Micro-LED" settings are configured. The XY-axis displacement platform 1 is adjusted until the upper vision module 4 / lower vision module 7 can observe the Micro-LED array. Using a visual recognition algorithm, the system automatically identifies the chips at both ends and rotates the upper stage 6 to align the boundary of the Micro-LED array with the upper boundary of the microscope lens view (the lens of the upper vision module 4 / lower vision module 7). Similarly, the lower stage 32, driven by the rotary motor 24, aligns the outer frame of the receiving substrate with the Micro-LED array, increasing transfer accuracy. Because the lower end of the upper stage 6 is horizontal, it remains parallel to the lower glass plate after rotation.

[0049] After leveling, adjust the size of the rectangle at the center of the auxiliary crosshairs, select the middle chip as the starting point, save the positions of the upper and lower glass plates, and "initialize the matrix". The following are the automated and manual methods.

[0050] Automation: The system reads the information group array information in the laser software and generates a rectangular array. Each rectangle corresponds to one chip. By selecting all the required rectangles, the corresponding chip can be laser printed.

[0051] Manual operation: Open the laser software, open the camera image to acquire the image of the Micro-LED array, open the information group, adjust the relevant parameters of the information group according to the shape, size and thickness of the chip and the thickness of the stamp, and select the required array chips one by one to emit lasers to achieve printing.

[0052] Chip orientation adjustment based on visual recognition algorithms: The system can identify Micro-LEDs of different sizes and shapes, automatically rotating the upper glass plate until the boundary of the Micro-LED array is aligned with the upper boundary of the microscope lens view. The upper and lower vision modules provide omnidirectional observation of the chips on the upper and lower stages; the upper lens typically observes more transparent chips, while the lower lens typically observes less transparent chips.

[0053] The above description is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A MicroLED mass transfer device, comprising a loading stage disposed above an XY-axis displacement platform; characterized in that: A leveling assembly is provided directly below the loading platform; the leveling assembly includes a connecting plate that is longitudinally slidably connected to the XY axis displacement platform, a download platform located directly above the connecting plate, three gas springs that are longitudinally arranged on the upper end of the connecting plate and evenly distributed along the circumference of the connecting plate, and a locking device located inside the connecting plate; wherein, the upper end of the gas spring abuts against the lower end of the download platform; the locking device can selectively lock the extension length of the gas spring.

2. The transfer device as claimed in claim 1, characterized in that: The upper end of the connecting plate is longitudinally slidably connected to three support rods evenly distributed along the circumference of the connecting plate; the lower end of the download platform is provided with three conical concave surfaces that are respectively opposite to the support rods; the upper end of the support rod is hemispherical and located within the concave surface of the cone; a spring is provided between the support rod and the download platform.

3. The transfer device as described in claim 2, characterized in that: The locking device consists of three locking rods that are laterally slidably connected within the connecting plate; the locking rods can be selectively engaged with the support rod.

4. The transfer device as described in claim 3, characterized in that: The connecting plate has three radially arranged vent chambers that are slidably and sealingly connected to the locking rod; the three vent chambers are interconnected.

5. The transfer device as claimed in claim 1, characterized in that: A through hole is formed in the center of the upper platform; a pressure plate frame for fixing the glass plate is provided at the lower end of the upper platform; a lower vision module is provided on the XY axis displacement platform below the pressure plate frame; and an upper vision module is provided on the XY axis displacement platform directly above the through hole.

6. The transfer device as claimed in claim 1, characterized in that: The upper end of the download platform is formed with three threaded through holes that pass through the download platform and are respectively opposite to the gas spring; each of the threaded through holes is detachably connected to a stud; the length of the stud is less than the depth of the threaded through hole; the upper end of the gas spring is hemispherical; the upper end of the gas spring is located in the threaded through hole and abuts against the lower end of the stud.

7. The transfer device as claimed in claim 1, characterized in that: The upper end of the XY-axis displacement platform is provided with a displacement assembly; the displacement assembly includes a support tube fixedly connected to the lower end of the connecting plate, a lifting motor provided on the XY-axis displacement platform for driving the support tube to slide longitudinally, and a rotary motor provided on the XY-axis displacement platform for driving the support tube to rotate circumferentially.

8. The transfer device as claimed in claim 7, characterized in that: The displacement assembly includes a mounting base disposed on the XY-axis displacement platform and a rotating ring rotatably connected to the upper end of the mounting base and driven by the rotary motor; the support tube is slidably connected in the axial direction within the rotating ring; the outer wall of the support tube is formed with a longitudinally arranged groove; the inner wall of the rotating ring is formed with a longitudinally arranged protrusion that is slidably connected to the groove.

9. The transfer device as claimed in claim 8, characterized in that: A longitudinal lead screw, coaxially arranged with the support tube, is rotatably connected to the mounting base; a lead screw nut, which is slidably connected to the longitudinal lead screw and is driven by the longitudinal lead screw, is slidably connected to the longitudinal lead screw; the lead screw nut abuts against the lower end of the support tube; and the longitudinal lead screw is driven by the lifting motor.

10. The transfer device as claimed in claim 9, characterized in that: The displacement assembly includes a transmission block that is laterally slidably connected to the mounting base and connected to the rotating ring drive, and a transverse lead screw that is rotatably connected to the mounting base and connected to the transmission block drive; the rotary motor is drively connected to the transverse lead screw.

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