Method and system for connecting board-to-board connectors

Abstract

To provide a method for connecting one connector in a substrate-to-substrate connector to the other connector while holding a flexible object, on which the one connector is mounted, with a robot hand.SOLUTION: A connection method for a substrate-to-substrate connector includes: a first measurement step of imaging a flexible object, in which a first component of the substrate-to-substrate connector is mounted on one face of a tip end, and calculating a position and a direction of a held part which is set to the tip end; a hold step of holding the held part with a robot hand based on the calculated position and direction of the held part; a second measurement step of measuring a position of the first component in a first direction; a third measurement step of measuring a position of the first component in a second direction; and a connection step of connecting the first component to a second component of the substrate-to-substrate connector based on the position of the first component calculated in the second measurement step and the third measurement step.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0003]

[0001] The present invention relates to the connection of board - to - board connectors, and more particularly, to a method and system for connecting board - to - board connectors mounted on flexible objects such as flexible printed circuit boards (FPCs) and flexible flat cables (FFCs) using a robot.

Background Art

[0002] For internal wiring of electronic devices, etc., strip - shaped FPCs or FFCs in which copper wiring is sandwiched between flexible resin films are used. For example, in Patent Document 1, the tip of a flexible cable is imaged with a stereo camera, the position and orientation of a gripped member (male connector) mounted on the tip are calculated, and it is gripped with the fingers at the tip of a robot hand, and then inserted into a joining member (female connector) on a printed circuit board from a direction parallel to the board surface to join the gripped member to the joining member.

[0003] Also, in order to miniaturize the connection part between a rigid board - shaped circuit board (hereinafter simply referred to as "circuit board") and an FPC or FFC, instead of mounting a connector on the FPC, etc., a reinforcing plate made of resin or the like is attached to the tip, and the FPC, etc. is directly inserted into the connector on the circuit board for connection. For example, in Patent Document 2, a flat cable provided with a reinforcing plate at the tip where a terminal pattern is formed is stocked in a fixed position, the flat cable is held by a suction part and gripping claws of a hand part, and the tip of the flat cable is inserted into a connector on a board from a direction substantially parallel to the board surface and slightly obliquely upward to connect the flat cable and the connector.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] In recent years, board-to-board connectors have been used to connect circuit boards to FPCs and other components in order to further increase the mounting density of circuit boards. Board-to-board connectors connect a pair of mating connectors by stacking them in the thickness direction, and are also called BtoB(registered trademark) connectors or stacking connectors. However, with conventional methods, it has been difficult to connect circuit boards and FPCs using board-to-board connectors with robots.

[0006] When connecting a circuit board and an FPC (Flexible Printed Circuit) using a board-to-board connector, one of the mating connectors, usually a female connector, is mounted on the circuit board. A reinforcing plate is attached to one side of the FPC's body, and the other connector is mounted on the opposite side. The two connectors are then stacked in the thickness direction, and the reinforcing plate is facing the circuit board. They are then mated and connected by pressing them together from a direction perpendicular to the circuit board. At this time, if force is applied while the stacked connectors are misaligned in the plane direction, the connectors may be mated at an angle or damaged. Therefore, it was necessary to precisely align the plane direction of the pair of connectors.

[0007] Generally, board-to-board connectors are small with very narrow terminal pitches, and connection work is performed in a situation where the connection surfaces of the pair of connectors cannot be seen, making it difficult to accurately align the plane of the two connectors.

[0008] The method described in Patent Document 1 involves bringing the gripped member, held by a finger, closer to the joining member, capturing an image of the gripped member positioned near the joining portion, and then estimating the three-dimensional position of the gripped member and the joining member through image processing. However, when using a board-to-board connector, it is not possible to visually confirm the state in which the connection surfaces of the pair of connectors are brought close together. Furthermore, the method described in Patent Document 2 involves holding a flat cable stored in a fixed position and inserting it into a connector in a fixed position, but Patent Document 2 does not specifically describe a method for aligning the positions of the two. Therefore, it was not possible to connect a board-to-board connector using the methods described in Patent Document 1 or Patent Document 2.

[0009] The present invention has been made in consideration of the above, and provides a method for holding a flexible object such as an FPC on which one connector of a board-to-board connector is mounted with a robotic hand, and connecting that one connector to the other connector. [Means for solving the problem]

[0010] The present invention provides a method for connecting a substrate-to-substrate connector, comprising: a first measurement step of capturing an image of a flexible object on which a first component of a substrate-to-substrate connector is mounted on one side of its tip, and obtaining a first image; and calculating the position and orientation of a portion to be held set on the tip of the flexible object based on the first image; a holding step of operating a robot hand to hold the portion to be held with a holding portion provided by the robot hand based on the position and orientation of the portion to be held calculated in the first measurement step; a second measurement step of measuring the position of the first component in a first direction; a third measurement step of measuring the position of the first component in a second direction; and a connection step of connecting the first component to the second component of the substrate-to-substrate connector based on the position of the first component calculated in the second and third measurement steps.

[0011] Here, the first and second components of a board-to-board connector are a pair of mating connectors, one being male and the other female. A flexible material is a planar, flexible board or wiring, and flexible materials include FPCs and FFCs. The first direction refers to the direction in which the terminals are arranged in parallel in the first component, and the second direction refers to the direction perpendicular to the first direction. In the following, the first direction may also be referred to as the width direction of the first component.

[0012] This method allows a robotic hand to hold a flexible object and connect a first component mounted on the held flexible object to a corresponding second component, even when the terminal pitch of the board-to-board connector is narrow.

[0013] In the above-described method for connecting a board-to-board connector, the second measurement step may involve capturing an image of the front end surface of the first component to acquire a second image, measuring the position of the first component in the first direction based on the second image, and the third measurement step may involve measuring the position of the front end surface of the first component in the second direction using a distance sensor. Here, the front end surface of the first component refers to the end surface on the front end side of the end surface extending in the first direction of the first component. The distance sensor refers to a sensor capable of measuring the distance to the object to be measured, and includes those generally called distance meters or displacement meters.

[0014] Alternatively, in the above-described method for connecting a board-to-board connector, the second measurement step may measure the position of the first component in the first direction by measuring the position of the side end face of the first component in the first direction using a distance sensor, and the third measurement step may measure the position of the first component in the second direction by capturing an image of the side end face of the first component and obtaining a third image, and based on the third image. Here, the side end face of the first component refers to the end face of the first component extending in the second direction.

[0015] Alternatively, in the above-described method for connecting a board-to-board connector, the second measurement step may involve capturing an image of the front end surface of the first component to acquire a second image, and measuring the position of the first component in the first direction based on the second image; and the third measurement step may involve capturing an image of the side end surface of the first component to acquire a third image, and measuring the position of the first component in the second direction based on the third image.

[0016] Alternatively, in the above-described method for connecting a board-to-board connector, the second measurement step may measure the position of the first component in a first direction by measuring the position of the side end face of the first component in a first direction using a first distance sensor, and the third measurement step may measure the position of the first component in a second direction by measuring the position of the front end face of the first component in a second direction using a second distance sensor.

[0017] Preferably, the distance sensor is a laser displacement meter. This makes measurement easier even when the object to be measured is small.

[0018] Preferably, in any of the above methods for connecting a substrate-to-substrate connector, the holding portion has a suction nozzle and a pair of width-direction restricting members, and in the holding step, after the portion to be held is held by suction by the suction nozzle, the portion to be held is positioned in the first direction by sandwiching it from both sides in the first direction with the pair of width-direction restricting members. As a result, even when the robot hand is operated at high speed while holding a flexible object, the portion to be held does not shift in the first direction, and the position of the portion to be held is stable.

[0019] Preferably, in any of the above methods for connecting a substrate-to-substrate connector, the holding portion has a suction nozzle and a tip regulating member, and in the holding step, after the portion to be held is held by suction using the suction nozzle, the tip regulating member is pressed against the portion to be held from the tip side, thereby positioning the portion to be held in the second direction. As a result, when the robot hand is operated at high speed while holding a flexible object, the portion to be held does not shift in the second direction, and the position of the portion to be held is stabilized.

[0020] Preferably, any of the above methods for connecting a board-to-board connector further includes a second component measurement step of capturing an image of the second component to obtain an image of the second component, and calculating the position and orientation of the second component based on the second component image, and in the connection step, the first component is connected to the second component based on the position and orientation of the first component and the second component. This makes it possible to connect the first component and the second component even when the terminal pitch of the board-to-board connector is even narrower to the point where the accuracy of the position in which the second component is supplied becomes a problem.

[0021] Preferably, in any of the above methods for connecting a board-to-board connector, the robot hand is equipped with a force sensor, and in the connection step, the force sensor is used to check for the presence or absence of a click sensation that occurs when the first and second parts are properly mated together, thereby determining whether the first and second parts are properly mated together. Here, the click sensation refers to a tactile sensation similar to pressing a switch. This makes it possible to stop the connection work and prevent damage to the first or second part even if the first and second parts are misaligned in the planar direction due to some reason when attempting to connect them.

[0022] Preferably, in any of the above methods for connecting board-to-board connectors, the board-to-board connector is a low-profile connector. The method for connecting board-to-board connectors of the present invention is particularly suitable for low-height, i.e., thin connectors.

[0023] Preferably, in any of the above methods for connecting a board-to-board connector, the flexible object is a flexible printed circuit board or a flexible flat cable, the held portion is a reinforcing plate formed on the side of the flexible printed circuit board or flexible flat cable opposite to the first component, the first measurement step is a step of identifying the region of the reinforcing plate in the first image and calculating the position and orientation of the reinforcing plate, and the holding step is a step of holding the reinforcing plate with the robot hand.

[0024] Preferably, in any of the above-described methods for connecting a board-to-board connector, the robot hand includes a plurality of the holding portions. Thereby, when continuously performing connection operations on connectors of different sizes, the amount of movement of the robot hand can be reduced.

[0025] Preferably, in any of the above-described methods for connecting a board-to-board connector, the robot hand includes a lighting unit that illuminates the front of the holding portion. This lighting unit can illuminate the held portion of the flexible object that is the work target of the robot hand and the second component.

[0026] The board-to-board connector connection system of the present invention includes a first camera that captures an image of a flexible object on which a first component of a board-to-board connector is mounted on one side of the tip portion to obtain a first image, a robot hand including a holding portion for holding a held portion set at the tip portion of the flexible object, a second camera that captures an image of the front end surface of the first component to obtain a second image, or a first distance sensor that measures the position of the side end surface of the first component, a third camera that captures an image of the side end surface of the first component to obtain a third image, or a second distance sensor that measures the position of the side end surface of the first component, and an arithmetic unit that calculates the position and orientation of the held portion based on the first image, and calculates the position of the first component from the measurement result by the second image or the first distance sensor and the measurement result by the third image or the second distance sensor.

Effects of the Invention

[0027] According to the method for connecting a board-to-board connector of the present invention, since the position and orientation of the held portion of the flexible object are measured in the first measurement step and held by the robot hand, even when the position where the flexible object is supplied is not constant, or when the flexible object is bent or twisted, it can be held by the robot hand. And, since the position of the first component mounted on the flexible object is measured in the second measurement step and the third measurement step, the first component can be accurately overlapped with the second component serving as a pair, and the first component and the second component can be connected.

Brief Description of the Drawings

[0028] [Figure 1] This figure shows a scenario in which the connection method for a board-to-board connector according to the first embodiment of the present invention is implemented. [Figure 2] This diagram shows the structure of the FPC and the first component, where A is an end view of the FPC divided in the width direction, B is a plan view of the FPC as seen from the first component side, and C is a plan view of the second component on the circuit board. [Figure 3] This figure shows the structure of the robot hand of the first embodiment, where A is a plan view seen from the side opposite the FPC, B is a lower side view of Figure 3A, and C is a left side view of Figure 3A. [Figure 4] This is a process flow diagram of the method for connecting a board-to-board connector according to the first embodiment. [Figure 5] This is a diagram illustrating the first measurement step of the method for connecting a board-to-board connector according to the first embodiment. [Figure 6] This is a diagram illustrating the holding step of the connection method for a board-to-board connector according to the first embodiment. [Figure 7] Figure A is a plan view and Figure B is a right side view of Figure 7A, illustrating the operation of the width-direction restricting member and the tip restricting member in the holding step of the connection method for substrate-to-substrate connectors according to the first embodiment. [Figure 8] This figure illustrates the second and third measurement steps of the method for connecting a board-to-board connector according to the first embodiment. [Figure 9] Figure A is a plan view and Figure B is a right side view of Figure 9A, illustrating the second and third measurement steps of the board-to-board connector connection method of the first embodiment. [Figure 10] This is a diagram illustrating the second component measurement step of the board-to-board connector connection method of the first embodiment. [Figure 11] This is a diagram illustrating the connection process of the board-to-board connector connection method of the first embodiment. [Figure 12] This is a diagram illustrating how to detect a click sensation using a force sensor. [Figure 13] This is a plan view showing the structure of another robot hand. [Figure 14] This is a plan view illustrating the second and third measurement steps of the board-to-board connector connection method according to the second embodiment. [Figure 15] This is a plan view illustrating the second and third measurement steps of the connection method for a board-to-board connector according to the third embodiment. [Figure 16] This is a plan view illustrating the second and third measurement steps of the board-to-board connector connection method of the fourth embodiment. [Modes for carrying out the invention]

[0029] A first embodiment of the method for connecting a board-to-board connector of the present invention will be described with reference to Figures 1 to 13. In this embodiment, an FPC (flexible printed circuit board) with a first component of a board-to-board connector mounted on one side of its tip is held by a robot hand, and the first component is connected to a second component of a board-to-board connector mounted on a circuit board.

[0030] Referring to Figure 1, the system 10 for implementing the board-to-board connector connection method of this embodiment includes a robot hand 80, a first camera 31, a second camera 32, a distance sensor 33, a second component imaging camera 34, and a calculation unit 30. The robot hand 80 is mounted on the tip of the arm of the robot 20. The positions of the first camera 31, the second camera 32, the distance sensor 33, and the second component imaging camera 34 are fixed. The first component 50 of the board-to-board connector is mounted on one side of the tip of the FPC 40, and the second component 70 of the board-to-board connector is mounted on the circuit board 60. The robot 20 holds the FPC 40 with the robot hand 80 and connects the first component and the second component. In the following, the robot hand may be simply referred to as the "hand".

[0031] The FPC 40 rises from between the housing 61 of the electronic device and the circuit board 60. The base end of the FPC 40 is fixed inside the housing 61 (not shown), and the tip of the FPC is in the air and is a free end. A free end means that the end of the FPC is not constrained and can move, twist, and bend.

[0032] Referring to Figure 2A, the FPC 40 consists of an FPC body 41 and a reinforcing plate 46. The FPC body 41 is formed by sandwiching copper wiring 43, which is formed by etching copper foil, between resin films 42 and 44 such as polyimide. At the tip of the FPC, one side of the resin film 44 is removed, forming an electrode portion (45 in Figure 2B) where the copper wiring 43 is exposed in a comb-like pattern. The first component 50 of the substrate-to-substrate connector is mounted on this electrode portion. The reinforcing plate 46 is attached to the side of the FPC opposite to the first component. In this embodiment, the reinforcing plate 46 is used as the holding portion to hold the FPC.

[0033] Thin sheets of stainless steel, polyimide, PET, etc., are used as the reinforcing plate 46. Because the FPC body 41 is flexible and easily bent, the reinforcing plate 46 prevents poor bonding with the first component and delamination of the first component due to stress concentration. Note that the scale in Figure 2 is not precise for the sake of explanation, and typically the thickness of the FPC body 41 is several tens of micrometers, and the thickness of the reinforcing plate 46 is several tens to 200 micrometers.

[0034] Referring to Figures 2A and 2B, the first component 50 is roughly rectangular in plan view and is mounted with its long side aligned with the width direction of the FPC 40. The first component has a roughly rectangular projection 52 on the connection surface 51 that connects to the second component 70. This projection 52 appears as two protrusions in a cross-section that divides the first component in the direction of its long side (Figure 2A). The terminal 53 is joined one-to-one with the copper wiring 43 of the FPC electrode portion 45 by soldering or the like, and extends from one side of the projection 52 over the top to the opposite side. The first component in this embodiment is a male connector for a board-to-board connector, also called a header or plug.

[0035] In this specification, the direction W in which the terminals 53 are arranged in parallel in the first component 50 is referred to as the first direction or the width direction of the first component, and the direction L perpendicular to the first direction is referred to as the second direction. Furthermore, of the end faces of the first component that extend in the first direction, the end face on the tip side is referred to as the tip face 54, and the end faces of the first component that extend in the second direction are referred to as the side end face 55.

[0036] Referring to Figure 2C, the second component 70 of the board-to-board connector mounted on the circuit board 60 is roughly rectangular in plan view and has a roughly rectangular projection 72 on the connection surface 71 that connects to the first component 50. The terminals 74 are each joined to wiring (not shown) on the circuit board 60 by soldering or the like, and extend from one side of the projection 72 over the top to the opposite side. Inside the projection 72, there is a recess 73 that is just the right size for the projection 52 of the first component to fit into. When the projection 52 of the first component fits into this recess 73, the terminals 53 and 74 come into contact, and the first component 50 and the second component 70 are connected.

[0037] The size of board-to-board connectors varies depending on the application, but those used to connect circuit boards and FPCs typically have a short side (width in the left-right direction in Figure 2) of about 2 to 5 mm, 6 to several tens of terminals, a terminal pitch of about 0.3 to 0.8 mm, and a height of about 0.5 to 3 mm when the first and second components are mated together. Larger connectors are used for joining circuit boards together, but the board-to-board connector connection method of this embodiment is suitable for low-profile connectors with an overall height of 3 mm or less in the mated state described above, and is particularly suitable for low-profile connectors with an overall height of 2 mm or less.

[0038] Returning to Figure 1, robot 20 is an articulated robot. Robot 20 has an arm 21 composed of multiple links 22 and joints 23, and a robot control unit 28. A hand 80, which is an end effector for holding the FPC 40, is attached to the tip of the arm 21.

[0039] The robot control unit 28 controls the movement of the entire robot 20, including the arm 21 and the hand 80. For example, the robot control unit receives instructions from the calculation unit 30 (described later) and calculates the rotation angle of each joint 23 required for the instructed movement, moves the hand 80 to the target position, and also causes the hand 80 to hold and release the FPC 40.

[0040] Referring to Figure 3, the robot hand 80 consists of a base member 81 and a holding portion 82 provided on one side thereof. The holding portion 82 has a suction nozzle 83, a pair of width-direction restricting members 86, 86, and a tip restricting member 89.

[0041] The suction nozzle 83 has a flat tip surface 84 with suction holes 85 formed therein. The suction holes communicate with a pressure reducing source 26 (not shown), and the nozzle holds the reinforcing plate 46 by adsorbing it, with the tip of the FPC facing left in Figures 3A and 3B. The number and arrangement of the suction holes are not particularly limited and can be designed to match the shape and size of the reinforcing plate. In addition, in the hand 80 of this embodiment, the suction nozzle 83 is eccentrically positioned from the axis of the connection part with the arm 21 to facilitate operation (see Figure 1).

[0042] Furthermore, the suction nozzle 83 presses the adsorbed reinforcing plate 46 to connect the first component 50 to the second component 70. The tip surface 84 of the suction nozzle 83 is preferably a rectangle with approximately the same dimensions as the first component in a plan view, so that the force is applied as evenly as possible to the entire first component when connecting the first and second components. A suction cup made of an elastic material may be attached to the tip of the suction nozzle 83. When a suction cup is attached to the suction nozzle, it is preferable to use a suction cup made of a material and shape that deforms little so that the displacement of the held FPC 40 in the direction perpendicular to the suction nozzle 83 does not become excessive.

[0043] A pair of width-direction restricting members 86 are positioned facing each other on both sides of the suction nozzle 83 in the first direction and are linearly movable in the first direction. This allows the pair of width-direction restricting members to move closer to each other along the slider 88 while the reinforcing plate 46 is attached to the suction nozzle 83, thereby positioning the reinforcing plate in the width direction by sandwiching it from both sides in the first direction. The tip portions 87 of the width-direction restricting members 86 protrude slightly from the tip surface 84 of the suction nozzle. The amount of protrusion of the tip portions 87 of the width-direction restricting members from the tip surface 84 of the suction nozzle must be small enough not to interfere with the second part or other members when connecting the first part 50 and the second part 70. Preferably, this protrusion amount is 100% to 200% of the thickness of the reinforcing plate 46. The width-direction restricting members may also be made movable in the vertical direction (the direction in which the first and second parts are connected) using springs or the like. This allows them to move vertically to avoid interference with other members during connection, thus preventing obstruction of the connection process. The width-direction restricting member 86 can be omitted, but by using the width-direction restricting member to restrict the width-direction position of the reinforcing plate 46, the reinforcing plate will not shift even when the hand 80 is operated at high speed while the FPC 40 is being held.

[0044] The tip regulating member 89 is positioned near the suction nozzle 83, on the tip side in the second direction, and is linearly movable in the second direction. This allows the reinforcing plate 46 to be positioned in the second direction by moving the tip regulating member 89 along the slider 91 toward the reinforcing plate while the reinforcing plate 46 is attached to the suction nozzle 83, and pressing it against the reinforcing plate 46 from the tip side. The tip portion 90 of the tip regulating member 89 protrudes slightly from the tip surface 84 of the suction nozzle. The amount of protrusion of the tip portion 90 of the tip regulating member from the tip surface 84 of the suction nozzle must be small enough, similar to the width direction regulating member, so as not to interfere with the second part or other members when the first part 50 is connected to the second part 70, preferably 100% to 200% of the thickness of the reinforcing plate 46. The tip regulating member may also be made movable in the vertical direction, similar to the width direction regulating member. The tip regulating member 89 can be omitted, but by using the tip regulating member to restrict the longitudinal position of the reinforcing plate 46, the reinforcing plate will not shift even when the hand 80 is operated at high speed while holding the FPC 40.

[0045] Returning to Figure 1, the hand 80 is equipped with a force sensor 92 at the connection point with the arm 21. The force sensor 92 is capable of detecting a force parallel to the suction nozzle in order to measure the force with which the suction nozzle 83 pushes the reinforcing plate 46 when the first component 50 and the second component 70 are connected. The mounting position of the force sensor 92 is not particularly limited as long as it can measure the force with which the suction nozzle 83 pushes the reinforcing plate 46, and may be mounted, for example, on the mounting part of the suction nozzle 83 to the base member 81.

[0046] The first camera 31 captures the tip of the FPC 40 from a direction that shows the reinforcing plate 46 and acquires a first image (see Figure 5). Preferably, the first camera is a 3D camera capable of acquiring a 3D image that includes 3D information of the object being imaged. The type of 3D camera is not particularly limited as long as it can acquire a 3D image, but preferably a stereo camera is used. The first image acquired by the first camera is transmitted to the calculation unit 30, which calculates the position and orientation of the reinforcing plate 46. Preferably, the first camera is capable of acquiring color information or brightness information. By using color information or brightness information, the calculation unit 30 can easily distinguish between the FPC body 41 and the reinforcing plate 46 in the first image.

[0047] The second camera 32 captures an image of the tip surface 54 of the first part 50 held by the hand 80 to acquire a second image (see Figure 8). Preferably, the second camera 32 is a two-dimensional camera. Generally, for the same price, a two-dimensional camera can produce images with higher resolution than a three-dimensional camera, so the position of the first part can be determined with higher precision. The second image acquired by the second camera is transmitted to the calculation unit 30, which calculates the position of the first part 50 in a first direction.

[0048] The distance sensor 33 measures the distance to the tip surface 54 of the first part 50 held by the hand 80 (see Figure 8). The type of distance sensor is not particularly limited as long as it can determine the position of a single point on the tip surface of the first part 50. Preferably, a distance sensor that uses a laser is preferred. This is because it is easy to accurately irradiate and measure even a minute area such as the tip surface 54 of the first part with a laser. The measurement result from the distance sensor is transmitted to the calculation unit 30, which calculates the position of the first part 50 in the second direction.

[0049] The second component imaging camera 34 captures an image of the second component 70 of the board-to-board connector mounted on the circuit board 60 by imaging the connection surface 71 of the second component 70. Preferably, the second component imaging camera 34 is a two-dimensional camera. Generally, for the same price, a two-dimensional camera can produce a higher resolution image than a three-dimensional camera, so the position of the second component can be determined with higher precision. The second component image acquired by the second component imaging camera is transmitted to the calculation unit 30, which calculates the position of the second component 70.

[0050] The camera 34 for imaging the second component can be omitted depending on the size of the terminal pitch of the board-to-board connector used. The first component 50, which is imaged by the second camera 32, is mounted on the opposite side of the reinforcing plate 46 held by the hand 80 as a separate component from the reinforcing plate 46, so its position in the planar direction is misaligned with that of the reinforcing plate due to manufacturing tolerances. In addition, the first component tends to have a large error in its relative position with the hand 80 because it moves at the moment the FPC 40, which is in a free-end state, is attracted to the hand 80. In contrast, the second component 70 is mounted on the circuit board 60 and supplied to a predetermined position, so its position and orientation errors are smaller than those of the first component. For this reason, if the terminal pitch of the board-to-board connector used is large enough, the first and second components can be connected without using the second component image. However, since there are errors in the mounting position of the second component on the circuit board and the supply position of the circuit board, it is preferable to use the camera for imaging the second component if the terminal pitch of the board-to-board connector is narrower than 0.4 mm.

[0051] The calculation unit 30 controls the entire system 10. Specifically, it issues imaging instructions to each camera and measurement instructions to the distance sensor 33. The calculation unit also performs various image processing and calculations, such as calculating the position and orientation of the reinforcing plate 46 based on the first image acquired by the first camera 31, calculating the position of the first component 50 based on the second image acquired by the second camera 32 and the measurement results of the distance sensor, and calculating the position of the second component 70 based on the second component image acquired by the second component imaging camera 34. Based on these calculated values, it then instructs the robot control unit 28 on the operation of the robot 20, the gripping operation of the hand 80, and the operation of the width direction restricting member and tip restricting member on the hand 80.

[0052] The physical configuration of the calculation unit 30 is not particularly limited. The calculation unit 30 may be a single physical device, or it may consist of multiple devices with distributed processing. Alternatively, the calculation unit 30 and the robot control unit 28 may be configured as a single physical device.

[0053] Next, the board-to-board connector connection method of this embodiment will be explained in accordance with the process flow shown in Figure 4.

[0054] (S1) First measurement process Referring to Figure 5, the first camera 31 captures the tip of the FPC 40 on which the first component 50 is mounted, and acquires the first image. The first image is a three-dimensional image containing three-dimensional information of the tip of the FPC. The purpose of acquiring the first image is to determine the position and orientation of the reinforcing plate 46, which is the part held by the hand 80. Therefore, the first camera is pre-positioned in a location where it can capture an image from the direction in which the reinforcing plate is visible.

[0055] The calculation unit 30 receives a first image from the first camera 31 and calculates the position and orientation of the reinforcing plate 46 in a three-dimensional coordinate system based on the first image. Here, the "orientation" of the reinforcing plate refers to the orientation of the reinforcing plate 46 in three-dimensional space. For example, if the first camera is a stereo camera, the first image consists of two images taken from different viewpoints. The calculation unit finds the corresponding points of the points to be measured on the two images and calculates the three-dimensional coordinates of the measurement points using the principle of triangulation from the corresponding points on each image and the distance between the viewpoints of the two images. Since the first camera 31 is installed in a fixed position, the calculation unit 30 can calculate the position of the reinforcing plate 46 in, for example, a world coordinate system or a robot coordinate system.

[0056] If the first image contains color information, the reinforcing plate 46 can be identified on the first image by utilizing the difference in color between the FPC body 41 and the reinforcing plate 46. If the first camera 31 is a stereo camera, the first image containing color information can be obtained by using a camera capable of acquiring color images. In 3D measurement using a stereo camera, the matching process, which searches for corresponding points on two images, is a process that causes measurement errors. However, the width of the reinforcing plate is usually approximately the same as the width of the FPC body, so there are few distinctive points and it is difficult to search for corresponding points. If the region of the reinforcing plate 46 can be identified in the first image using color information, the corners of that region can be used as feature points to perform the matching process.

[0057] Furthermore, if the first image includes brightness information, the reinforcing plate can be identified in the first image by utilizing the optical characteristics of the FPC body 41 and the reinforcing plate 46, such as the difference in reflectivity. If the reinforcing plate is made of a highly reflective metal, the area of ​​the reinforcing plate 46 can be identified in the first image by illuminating the tip of the FPC 40 with strong light and taking an image of it, based on the difference in brightness.

[0058] If it is difficult to identify the area of ​​the reinforcing plate 46 in the first image based on color information or brightness information, for example, multiple reference images or CAD data with different positions and orientations of the FPC 40 can be prepared, and the reinforcing plate and the FPC body can be identified by pattern matching with the first image. Alternatively, the corners or edges of the FPC tip can be used as clues to extract the contour of the tip, and the reinforcing plate can be identified by specifying two edges or three corners of the reinforcing plate. Details of the latter method are disclosed in Japanese Patent Publication No. 2020-037147 and Japanese Patent Publication No. 2020-041862 by the present applicant.

[0059] (S2) Holding process Referring to Figure 6, the calculation unit 30 instructs the robot control unit 28 to have the hand 80 hold the reinforcing plate based on the calculated position and orientation of the reinforcing plate 46. The hand 80 approaches the reinforcing plate 46 from a direction perpendicular to it and holds the reinforcing plate by suction with the suction nozzle 83.

[0060] Referring to Figure 7, with the reinforcing plate 46 attached to the suction nozzle 83, the reinforcing plate 46 is positioned in the first direction by sandwiching it from both sides in the first direction with a pair of width-direction restricting members 86, 86. Furthermore, the reinforcing plate is positioned in the second direction by pressing the tip restricting member 89 against the reinforcing plate 46 from the tip side. Note that the order in which the width-direction restricting members and the tip restricting members are operated is not particularly limited; the second direction may be positioned first, and then the first direction may be positioned.

[0061] (S3) Second measurement process Referring to Figures 8 and 9, the calculation unit 30 instructs the robot control unit 28 to move the hand 80 holding the reinforcing plate 46 to a predetermined position and in a predetermined posture, so that the tip surface 54 of the first part 50 is directed toward the second camera 32 and the distance sensor. The second camera 32 captures an image of the tip surface 54 of the first part and acquires a second image.

[0062] As mentioned above, the second image does not need to be a three-dimensional image; rather, it is preferable to have a high-resolution two-dimensional image. The resolution of the second image is preferably such that the size of a single pixel is 1 / 5 or less of the terminal pitch, and more preferably 1 / 10 or less. This makes it possible to measure the position of the first component with sufficiently high accuracy, and the probability of failure in connecting the first and second components can be kept extremely low. The resolution of the second image can be adjusted by the specifications of the second camera 32 and the imaging distance when capturing the second image.

[0063] The calculation unit 30 receives a second image from the second camera 32 and calculates the position of the first part in the first direction W based on the second image. The position of the first part can be determined, for example, by preparing a reference image taken of the tip surface 54 of the first part from the same distance as when the second image was taken, and performing pattern matching processing between the second image and the reference image. The position of the first part 50 in the first direction relative to the hand 80 can be directly obtained from the second image. Since the calculation unit knows the position and orientation of the second camera and the hand 80, it can calculate the position of the first part in the first direction in the world coordinate system or robot coordinate system based on the second image. Alternatively, as a method other than pattern matching, for example, edge detection may be performed on the second image, and the position in the first direction may be determined at the position of a specific edge detected (for example, the end of the tip surface 54 in the first direction).

[0064] (S4) Third measurement process The distance from the distance sensor 33 to the tip surface 54 of the first part 50 (the distance in the second direction L in Figure 9A) is measured. Since the calculation unit 30 knows the position and orientation of the distance sensor and the hand 80, it can calculate the position of the first part in the second direction L relative to the hand, as well as the position of the first part in the second direction in the world coordinate system and the robot coordinate system, based on the measurement result of the distance sensor.

[0065] The position of the first component 50 can be determined from the results of the second measurement process (S3) and the third measurement process (S4). Since the orientation of the first component is approximately the same as the orientation of the reinforcing plate 46, it can be considered known from the first measurement process onward.

[0066] (S5) Second part measurement process Referring to Figure 10, the second component imaging camera 34 captures the connection surface 71 of the second component 70 of the board-to-board connector on the circuit board 60 from above to acquire an image of the second component. If the hand 80 or FPC 40 is not in a position to hide the second component 70 from the second component imaging camera 34 when the second image is being captured, the second image and the second component image can be captured simultaneously. The second component image, like the second image, does not need to be a three-dimensional image; rather, a high-resolution two-dimensional image is preferable. The preferred resolution for the second component image is the same as for the second image.

[0067] The calculation unit 30 receives an image of the second component from the second component imaging camera 34 and calculates the position and orientation of the second component 70 based on the second component image. Here, the "orientation" of the second component refers to the orientation of the second component in a plane parallel to the circuit board 60. The position of the second component can be determined by preparing a reference image taken of the connection surface 71 of the second component from the same distance as when the second component image was captured, and performing a pattern matching process between the second component image and the reference image. Since the calculation unit knows the position and orientation of the second component imaging camera, it can calculate the position and orientation of the second component in the world coordinate system and the robot coordinate system based on the second component image.

[0068] (S6) Connection process Referring to Figure 11, the calculation unit 30 instructs the robot control unit 28 to insert the first part 50 into the second part 70 based on the position of the first part calculated in the second measurement step (S3) and the third measurement step (S4), and the position of the second part calculated in the second part measurement step (S5). Specifically, the hand 80 is moved to align the connection surface 51 of the first part with the connection surface 71 of the second part, and the first part is placed on top of the second part. Then, the hand 80 pushes the first part 50 downward perpendicular to the circuit board 60, inserting the protrusion 52 of the first part 50 into the recess 73 of the second part 70.

[0069] When inserting the first component 50 into the second component 70, preferably, a force sensor 92 is used to check for the presence or absence of a click sensation that occurs when the first and second components are properly mated. The force sensor 92 detects the force exerted by the hand 80 when it pushes the first component into the second component, by the reaction force. A click sensation is a tactile sensation similar to pressing a switch. More specifically, a click sensation is a sensation where resistance increases as the hand pushes the first component into the second component, and then disappears once the first component reaches its limit. Board-to-board connectors are usually designed to produce a click sensation when properly mated.

[0070] Figure 12 shows the click sensation observed in the experiment. The hand 80 was lowered at a constant speed to insert the first part 50 into the second part 70. When the surface misalignment of the first and second parts was sufficiently small and they were properly fitted together, the force sensor's detected value (hereinafter referred to as "force value") increased to approximately 10N, then dropped sharply, and then increased again as the hand 80 moved forward. This sharp drop in the force value represents the click sensation. When the first and second parts were not properly fitted together (the line labeled "abnormal" in Figure 12), the force value increased monotonically to approximately 15N.

[0071] By checking for the presence or absence of a click sensation using the force sensor 92, even if the first part 50 and the second part 70 are misaligned in the planar direction due to some reason when attempting to connect them, the connection work can be stopped to prevent damage to either the first or second part.

[0072] When the force sensor 92 detects a click and confirms that the first component 50 and the second component 70 are properly mated, the first component is pushed further to complete the connection. In board-to-board connectors, the amount of force to be applied during connection is specified in the specifications. For example, in the board-to-board connector used in the experiment in Figure 8, a force of 50N is required to connect the first component and the second component. In Figure 12, the experiment was terminated at 15N, which does not cause damage even if the first and second components are not properly mated. However, in actual connection work, the presence or absence of a click is checked up to approximately 15N, and if a click is confirmed, the first component is pushed further until the specified force (50N) is reached.

[0073] The above steps complete the connection between the boards and the board connectors.

[0074] The advantages of the board-to-board connector connection method of this embodiment will be explained again.

[0075] The tolerance for the misalignment between the first component 50 and the reinforcing plate 46 due to manufacturing errors is approximately 0.1 mm. In addition, the FPC 40, which is in a free-end state, moves slightly at the moment it is picked up by the suction nozzle 83, and the resulting deviation of the holding position from the design position is estimated to be up to approximately 0.2 mm. Of this, the deviation that occurs at the moment of picking up can be significantly reduced by correcting the position of the reinforcing plate after picking up using the width-direction restricting member and the tip restricting member (hereinafter collectively referred to as the "restricting members"), even considering the processing accuracy of the hand 80 and the restricting members. On the other hand, regarding the second component 70, the error in the mounting position of the second component on the circuit board 60 is up to approximately 0.1 mm, and the error in the placement position of the circuit board during connection work is up to approximately 0.1 mm.

[0076] Therefore, if an attempt is made to connect the first component 50 to the second component 70 without measuring the position of the first component 50, the misalignment of the connection surfaces 51 and 71 of the two components will be up to about 0.5 mm without using a regulating member, and up to about 0.3 mm even with a regulating member. If the terminal pitch is 0.6 mm or less, the probability of connection failure increases. In contrast, with the board-to-board connector connection method of this embodiment, the position of the first component is measured by the second and third measurement steps before connection, so even if the terminal pitch is 0.6 mm or less, the probability of connection failure is extremely small.

[0077] Furthermore, even if the position of the first component 50 relative to the hand 80 is accurately measured, if an attempt is made to connect the first component 50 and the second component 70 without measuring the position of the second component 70, the misalignment of the connection surfaces 51 and 71 of the two components will be up to approximately 0.2 mm, and if the terminal pitch is 0.4 mm or less, the probability of connection failure will increase. In contrast, according to the board-to-board connector connection method of this embodiment, in addition to the second and third measurement steps, the position of the second component is measured by the second component measurement step and then connected, so even if the terminal pitch is 0.4 mm or less, the probability of connection failure becomes extremely small.

[0078] Next, I will explain a modified example of a robotic hand.

[0079] Referring to Figure 13, this modified robot hand differs from the hand 80 shown in Figure 3 in that it has multiple holding parts and an illumination unit. The hand 80a has a base member 81 and two holding parts 82 and 82a, with an illumination unit 93 between the two holding parts. The hand 80a is connected to the arm 21 at the midpoint between the two holding parts, i.e., on the back side of the illumination unit.

[0080] One of the holding parts 82 is the same as the holding part shown in Figure 3. The other holding part 82a has a substantially square tip surface 84a of the suction nozzle 83a and has one suction hole 85a. As mentioned above, the number and arrangement of suction holes provided by the suction nozzle are not particularly limited. In the hand 80a shown in Figure 13, both holding parts 82 and 82a are designed to hold FPCs of different sizes. This allows for the continuous connection of board-to-board connectors of different sizes in the assembly process of a single electronic device, etc., by simply moving the hand 80a slightly. The number of holding parts on the hand is preferably two or less. If the number of holding parts on the hand is too large, other holding parts are more likely to interfere with the surroundings during connection and other operations.

[0081] The illumination unit 93 is provided between the holding units 82 and 82a and illuminates the front of the holding units. This allows the reinforcing plate 46 to be illuminated when capturing the first image, and the circuit board 60 and the second component 70 to be illuminated when capturing the second component image. A panel-type illumination unit can be suitably used as the illumination unit. If the hand does not have an illumination unit, a ring illumination or flat dome illumination will be inserted between the second component imaging camera 34 and the second component in order to illuminate the second component, especially during the second component measurement process. By having the illumination unit provided by the hand illuminate the object to be imaged, the time required for inserting and removing ring illumination, etc., can be eliminated, thereby shortening the working time.

[0082] The illumination unit 93 is positioned so that the imaging target is not obstructed by the FPC body 41 when the holding unit holds the FPC. Alternatively, the illumination unit 93 may be provided on a hand with a single holding unit, such as the hand 80 in Figure 3.

[0083] Next, a second embodiment of the method for connecting a substrate-to-substrate connector according to the present invention will be described with reference to Figure 14. The second and third measurement steps will be described below. Other aspects are the same as in the first embodiment.

[0084] In the second measurement step, in the first embodiment, the position of the first part in the first direction W was measured based on a second image taken of the tip surface 54 of the first part using a second camera 32 located in the second direction L as viewed from the first part 50. In contrast, in this embodiment, the position of the first part in the first direction W is measured by measuring the distance to the side end surface 55 of the first part using a distance sensor 37 located in the first direction W as viewed from the first part 50.

[0085] In the third measurement step, in the first embodiment, the position of the first part in the second direction L was measured by measuring the distance to the tip surface 54 of the first part using a distance sensor 33 located in the second direction L as viewed from the first part 50. In contrast, in this embodiment, the position of the first part in the second direction L is measured based on a third image taken of the side end surface 55 of the first part using a third camera 36 located in the first direction W as viewed from the first part 50.

[0086] Next, a third embodiment of the method for connecting a substrate-to-substrate connector according to the present invention will be described with reference to Figure 15. The second and third measurement steps will be described below. Other aspects are the same as in the first and second embodiments.

[0087] The second measurement step, similar to the first embodiment, measures the position of the first part in the first direction W based on a second image of the tip surface 54 of the first part, using a second camera 32 located in the second direction L as viewed from the first part 50. The third measurement step, similar to the second embodiment, measures the position of the first part in the second direction L based on a third image of the side end surface 55 of the first part, using a third camera 36 located in the first direction W as viewed from the first part 50.

[0088] Next, a fourth embodiment of the method for connecting a substrate-to-substrate connector according to the present invention will be described with reference to Figure 16. The second and third measurement steps will be described below. Other aspects are the same as in the first to third embodiments.

[0089] The second measurement step, similar to the second embodiment, measures the position of the first part in the first direction W by measuring the distance to the side end face 55 of the first part using a first distance sensor 38 located in the first direction W as viewed from the first part 50. The third measurement step, similar to the first embodiment, measures the position of the first part in the second direction L by measuring the distance to the front end face 54 of the first part using a second distance sensor 39 located in the second direction L as viewed from the first part 50.

[0090] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of its technical concept.

[0091] For example, although the above embodiments were described assuming the workpiece is an FPC40, the workpiece may also be an FFC. Although FPCs and FFCs have different manufacturing methods, they have similar structures with respect to the portion on which the first component of the board-to-board connector is mounted. Therefore, the method for connecting a board-to-board connector according to the present invention can be similarly applied to flexible materials that are FPCs or FFCs. Furthermore, the present invention can also be applied to flexible materials other than FPCs and FFCs, as long as the first component of the board-to-board connector is mounted on one side of the tip portion of the flexible material.

[0092] Furthermore, in each of the above embodiments, the work was performed using the reinforcing plate 46 attached to the FPC 40 as the part to be held. However, the present invention can also be applied to FPCs that do not have a reinforcing plate attached. Normally, the reinforcing plate is attached to the side of the FPC or FFC opposite to the first component. However, even if the reinforcing plate is not attached for some reason, the part on which the first component is mounted is deformed by the rigidity of the first component, and is substantially the same as a state in which a reinforcing plate has been formed. Therefore, the connection work of the board-to-board connector can be performed using the part on the back of the first component of the FPC or FFC as the part to be held.

[0093] Furthermore, in each of the above embodiments, the hand 80 held the FPC 40 by suction, but the holding method is not limited to this. For example, the robot hand may hold the FPC by gripping its side edge. In that case, in the first measurement step, the position and orientation of the edge of the FPC to be held are measured.

[0094] Furthermore, although the above embodiments show examples in which the second component 70 is mounted on the circuit board 60, the invention is not limited to this, and the second component may be mounted on, for example, another flexible material.

[0095] Furthermore, in each of the above embodiments, the hand 80 holding the FPC 40 on which the first component is mounted is operated based on the calculated position of the first component 50 to connect it to the corresponding second component 70. However, if possible, the first and second components may be connected by moving the second component. For example, the circuit board on which the second component is mounted or another flexible object may be held by another robot hand, etc., and brought closer to the first component held by the hand 80 to connect them. Alternatively, the circuit board on which the second component is mounted may be connected while its position is finely adjusted using an XY stage, etc., that can move in a direction perpendicular to the connection direction of the connector.

[0096] Furthermore, the installation positions of each camera and distance sensor are not particularly limited and can be fixed or movable. For example, the second camera 32 and distance sensor 33 may be mounted on the hand 80, or they may be mounted on a robot hand separate from the hand 80. [Explanation of symbols]

[0097] 10 Board-to-board connector connection systems 20 Robots 21 Arms 22 links 23 joints 26. Pressure reduction source 28 Robot Control Unit 30 Arithmetic section 31. Camera 1 32. Second camera 33 Distance Sensor 34. Camera for imaging the second component. 36 Third Camera 37 Distance Sensor 38. First distance sensor 39. Second distance sensor 40 FPC (Flexible) 41 FPC main unit 42 Resin film 43 Copper Wiring 44 Resin film 45 Electrode part 46 Reinforcement plate (held part) 50 First component of board-to-board connector 51 Connection surface 52 protrusion 53 terminals 54 Tip surface 55 Side end face 60 Circuit boards 61. Enclosures of electronic devices 70 Second component of board-to-board connector 71 Connection surface 72 protrusion 73. Indentation 74 terminals 80, 80a Robot Hand 81 Base member 82, 82a holding part 83, 83a Suction nozzle 84, 84a Tip surface 85, 85a Adsorption holes 86 Width direction restricting member 87 Width direction restricting member tip 88 Slider 89. Tip regulating member 90 Tip of the regulating member 91 Slider 92 Force Sensor 93 Lighting Section W First direction L 2nd direction

Claims

1. A first measurement step involves capturing an image of a flexible printed circuit board or flexible flat cable on which a first component of a board-to-board connector is mounted on one side of the tip, acquiring a first image, and calculating the position and orientation of a reinforcing plate attached to the side of the tip of the flexible printed circuit board or flexible flat cable opposite to the first component based on the first image. Based on the position and orientation of the reinforcing plate calculated in the first measurement step, the robot hand is operated to hold the reinforcing plate by adsorption using the suction nozzle of the holding part provided on the robot hand; The process of positioning the reinforcing plate in the first direction by sandwiching the reinforcing plate from both sides in the first direction with the width-direction restricting members of the holding portion, The process of positioning the reinforcing plate in a second direction by pressing the tip regulating member of the holding portion against the reinforcing plate from the tip side, A second measurement step for measuring the position of the first part in a first direction, A third measurement step for measuring the position of the first component in the second direction, A connection step in which the first component is connected to the second component of the board-to-board connector based on the position of the first component calculated in the second and third measurement steps, A method for connecting board-to-board connectors having the following features.

2. The second measurement step involves capturing an image of the tip surface of the first component to obtain a second image, and measuring the position of the first component in the first direction based on the second image. The third measurement step measures the position of the first part in the second direction by measuring the position of the tip surface of the first part in the second direction using a distance sensor. A method for connecting a board-to-board connector according to claim 1.

3. The second measurement step measures the position of the first part in the first direction by measuring the position of the side end face of the first part in the first direction using a distance sensor. The third measurement step involves capturing an image of the side end face of the first component to obtain a third image, and measuring the position of the first component in the second direction based on the third image. A method for connecting a board-to-board connector according to claim 1.

4. The second measurement step involves capturing an image of the tip surface of the first component to obtain a second image, and measuring the position of the first component in the first direction based on the second image. The third measurement step involves capturing an image of the side end face of the first component to obtain a third image, and measuring the position of the first component in the second direction based on the third image. A method for connecting a board-to-board connector according to claim 1.

5. The second measurement step measures the position of the first part in the first direction by measuring the position of the side end face of the first part in the first direction using the first distance sensor, The third measurement step measures the position of the first part in the second direction by measuring the position of the tip surface of the first part in the second direction using a second distance sensor. A method for connecting a board-to-board connector according to claim 1.

6. The process further includes a second component measurement step of capturing an image of the second component to obtain a second component image, and calculating the position and orientation of the second component based on the second component image. In the connection step, the first component is connected to the second component based on the position and orientation of the first component and the second component. A method for connecting a board-to-board connector according to claim 1.

7. The robot hand comprises a plurality of the holding parts. A method for connecting a board-to-board connector according to claim 1.

8. The robot hand is equipped with a lighting unit that illuminates the area in front of the holding part. A method for connecting a board-to-board connector according to claim 1.

9. A first camera that captures a first image of a flexible printed circuit board or flexible flat cable on which a first component of a board-to-board connector is mounted on one side of the tip, A robot hand comprising a holding section having a suction nozzle for adsorbing and holding a reinforcing plate attached to the side of the tip of the flexible printed circuit board or flexible flat cable opposite to the first component, a width direction restricting member for positioning the reinforcing plate in the first direction by sandwiching the adsorbed reinforcing plate from both sides in the first direction, and a tip restricting member for positioning the reinforcing plate in the second direction by pressing it against the adsorbed reinforcing plate from the tip side, A second camera that captures the tip surface of the first component and acquires a second image, or a first distance sensor that measures the position of the side end surface of the first component, A third camera that captures an image of the side end face of the first part and acquires a third image, or a second distance sensor that measures the position of the side end face of the first part, A calculation unit calculates the position and orientation of the reinforcing plate based on the first image, and calculates the position of the first component from the second image or the measurement result from the first distance sensor, and the measurement result from the third image or the second distance sensor. A connection system for board-to-board connectors.

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