KR101029379B1 - connector - Google Patents

Abstract

<Task>

The present invention provides a connector having a high contact reliability, which is capable of high-speed transmission of high-frequency signals, has excellent reliability, and has a flat plate-like connection object in which ground lines and ground layers positioned on opposite sides are electrically connected.

<Solution>

A signal line (S) and a ground line (G) are provided on one side, and a flat plate-like connection object (100) having a ground layer (GL) that is not continuous with the ground line can be inserted and removed. A signal contact 50 having contact portions 54 and 55 electrically contacting the insulator 20 and a signal line, and a two-pronged contact portion 44 contacting the ground line and the ground layer to sandwich the connection object. Ground contacts 40 having 45, 46, 47;

Connector, high frequency signal, ground line, ground layer

Description

Connector

The present invention relates to a connector capable of improving transmission characteristics of a transmission signal.

In recent years, high-frequency signals are required to be transmitted at high speed in flat-shaped connection objects such as FFC (Flexible Flat Cable) and FPC (Flexible Printed Circuit) and connectors to which they are connected. In order to meet this demand, crosstalk must be reduced and noise countermeasures must be taken.

The FPC cable (connected object) and the connector of JP-A-2001-68907 have been invented in response to this problem. On one side of the cable of Japanese Patent Laid-Open No. 2001-68907, a plurality of signal lines and a plurality of ground lines positioned between each signal line are formed to be parallel to each other, and on the other side, the ground is connected through a bump through the inside of the FPC cable. The ground layer which electrically connects with a line is formed.

On the other hand, the connector is provided with a contact (signal terminal) contacting the signal line fixed to the insulator (connector housing), and a cell covering the contact fixed to the insulator and the FPC cable and contacting the ground layer. The signal terminal is connected to the signal circuit (contact pad) of the printed wiring board, and the cell is grounded to the ground circuit of the printed wiring board. Therefore, crosstalk between signal lines of the FPC cable is reduced by the ground line, and noise is blocked by the cell.

Since the FPC cable of Japanese Patent Laid-Open No. 2001-68907 requires a bump to electrically connect the ground line formed on one side and the ground layer formed on the other side, the configuration is complicated and therefore, the manufacturing cost is high. Becomes high.

In addition, since FPC cables are often used in places that require flexibility while repeatedly transmitting signals, such as hinge parts of mobile phones, due to the characteristics of urinability, fine bumps in FPC cables can be achieved. If the through hole is formed, stress concentration occurs during bending, and in the worst case, there is a risk of conduction failure due to disconnection.

In addition, if bumps or through holes are formed in the vicinity of the contact portion of the FPC cable, it becomes a dead space and there is a problem in that not only the FPC cable but also the connector that is the connecting object becomes larger.

In addition, when the connection object is an FFC which is cheaper than the FPC cable, a ground line is arranged inside the FFC, and a ground layer is formed on one side, and then the ground line and the ground layer are connected by bumps or through holes. Since it is not possible in the manufacturing structure, the above effects cannot be exhibited.

An object of the present invention is to provide a high-speed transmission of high-frequency signals, excellent reliability, low-cost flat plate connection objects in which ground lines and ground layers located on opposite sides are not electrically connected, and high contact reliability. To provide.

The connector of the present invention is provided with an insulator having a signal line and a ground line on one side and a flat plate-like connection object formed with a ground layer that is not continuous with the ground line on the other side; And a contact portion in electrical contact with the signal line. And a two-pronged contact portion for holding the connection object while contacting the signal contact supported by the insulator, the ground line and the ground layer, respectively, and a ground contact supported by the insulator.

The connection object contacts the one of the signal contact and the ground contact, thereby supporting the insulator with an actuator that raises at least one of the contact pressure between the connection object and the signal contact and the contact pressure between the connection object and the ground contact. It is preferable.

In addition, it is preferable to form a holding means for regulating the movement in the direction in which the connected object is pulled out by engaging the connected object inserted into the insulator between the insulator and the actuator.

Since the connector of the present invention has a ground contact having a two-shaped connection portion connected to the ground line and the ground layer of the plate-shaped connection object, the ground object and the ground layer are not continuous with each other, so that the reliability is high. In addition, even if it is formed inexpensive, the ground line and the ground layer can be grounded to the circuit board. In addition, since the ground line and the ground layer are not continuous with each other, it is possible to set the connection object as an FFC.

In addition, the crosstalk between the signal lines can be reduced by the ground line, and external noise and the like can be reduced by the ground layer, making it easy to realize high-speed transmission of high frequency signals.

According to the configuration as described in claim 2, at least one of the contact pressure between the connection object and the signal contact and the contact pressure between the connection object and the ground contact is increased by the actuator, so that the signal can be transmitted reliably.

When the holding means is provided as in the invention described in claim 3, the movement of the connection object inserted into the insulator can be restricted.

In addition, when the actuator is provided, contact operation with the connection object of the actuator, the signal contact, and the ground contact becomes easy.

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of this invention is described, referring an accompanying drawing. In addition, each direction of back, front, left, and right of a following description is based on the arrow of a figure.

The connector 10 of the embodiment is incorporated in a so-called MEP (Multifunction Peripheral), an optical drive, a mobile terminal, or the like, for example, a printer having a scanner function or a fax function. And an end portion of a flexible printed circuit (FPC) or a flexible flat cable (FFC).

The FFC 100, which is a plate-shaped mount, is elastically deformable in its entirety and has a laminated structure as shown in FIG. That is, a plurality of signal lines (S) and ground lines (G) are formed on one side of the elastic base material (102) to be parallel to each other, and the ground layer (GL) is formed on the other surface of the base material (102). Is formed. The parts except both ends of each signal line (S) and each ground line (G) are coated with a cover layer (103) made of an insulating material capable of elastic deformation, and the parts except both ends of the ground layer (GL) are capable of elastic deformation. It is coated with a cover layer 104 of insulating material. In addition, both ends of the ground layer GL are separated from the surface of the base material 102, and end reinforcement 105 made of an insulating material is positioned between both ends of the ground layer GL and both ends of the base material 102.

Both ends of the FFC 100 (parts other than the engaging projection 101) are narrower than portions except the both ends, and the engaging projections 101 are provided on both sides of the both ends. In this embodiment, the ground line G is arrange | positioned on both sides of the signal line S of 8 or less, the ground line G is 5, and two pairs of signal lines S which comprise a differential pair.

The connector 10 has a structure described below, and includes an insulator 20, a ground contact 40, a signal contact 50, and an actuator 60 as main components.

The insulator 20 is injection molded of an insulating and heat resistant synthetic resin material. In the vicinity of both sides of the insulator 20, an insertion groove 21 extending downward is concave, and the actuator supporting portion 22 constituting the both ends of the insulator 20 faces upward from its lower end. An extended locking recess 23 is formed. A pair of left and right side walls 24 are provided inside the right and left insertion grooves 21, and recesses 25 are recessed downwards on the upper surfaces of the left and right side walls 24. (See FIG. 8, FIG. 13) In the space surrounded by the rear wall 28 and the left and right side walls 24, which are lower in dimension than the front wall 27 and the front wall 27 of the insulator, and open up and down, the left and right both ends thereof are left and right. Partition walls 29 are connected to the side walls 24, respectively. On the opposite surface of the rear wall 28 and the partition wall 29, fixing grooves 31 extending in the vertical direction to press-fit the indentation portion 43 of the ground contact 40 and the indentation portion 53 of the signal contact 50. ) Is arranged concave in a total of 13 in parallel to the left and right, the fixing groove 31 corresponding to the deformation allowance groove 32 of 13 in total on the opposite surface of the front wall (27) and the partition wall (29). It is concavely installed in the form located immediately before the. In addition, at the connecting portion between the front wall 27 and the left and right side walls 24, the engaging protrusion insertion groove 34 extending downward from the upper surface of the corresponding portion is concavely installed, and the engaging protrusion is formed at the upper end of the side wall 24. A temporary fixed protrusion protruding in the insertion groove 34 is formed.

A total of eight ground contacts 40 and five signal contacts 50 in total are integrally obtained by stamping molding. After base plating (for example, nickel plating) is performed on a base material obtained by stamping molding (for example, phosphor bronze, beryllium copper alloy, titanium copper, stainless steel, and colosone copper alloy), finish plating (for example, For example, it is an elastic and conductive member produced by performing gold plating, silver (signal line Sn)-copper (Cu) plating, tin (signal line Sn)-lead (Pb) plating).

The ground contact 40 is substantially horizontal, with the horizontal portion 41 having the tail portion 42 at the rear end and the front end of the indentation portion 43 and the ground contact 40 extending upward near the rear end portion of the horizontal portion 41. The first elastic deformation portion 44 (contact portion), which extends upward from the portion and then upwards, and is provided so that the contact protrusion 45 (contact portion) protrudes at the upper end, and in the vicinity of the lower end portion of the press-in portion 43. The second elastic deformation portion 46 (contact portion), which extends upward and then extends upward (may be a structure extending from the horizontal portion 41) and is provided so that the contact protrusion 47 (contact portion) protrudes at the upper end thereof. Equipped. Each ground contact is press-fitted into the insulator 20 in the arrangement shown by pressing the press-in portion 43 into the corresponding fixing groove 31 of the insulator 20, and the first contact of each ground contact 40 The front part (extending in the vertical direction) of the elastic deformation part 44 is located inside the corresponding deformation allowance groove 32. When the ground contact 40 is in the free state, the gap between the contact protrusion 45 of the first elastic deformation portion 44 and the contact protrusion 47 of the second elastic deformation portion 46 is formed at the end of the FFC 100. Slightly wider than plate thickness

The signal contact 50 has a horizontal portion 51 having a tail portion 52 at the front end substantially horizontally, an indentation portion 53 extending upward from the rear end portion of the horizontal portion 51, and a lower portion near the lower end portion of the indentation portion. After extending forward, it extends upward and has an elastic deformation portion 54 (contact portion) provided at its upper end so as to protrude a contact projection portion 55 (contact portion). Each ground contact 50 constitutes a pair of two pairs, and the insulator 20 is press-fitted into the fixing groove 31 in which the differential pairs are located between the adjacent ground contacts 40. It is fixed to). The front portion (extended in the vertical direction) of the elastic deformation portion 54 of each signal contact 50 is located inside the corresponding deformation allowance groove 32.

The tail portion 42 of each ground contact 40 is soldered to a ground pattern (not shown) on the circuit board CB (shown in FIGS. 1 and 6, other figures are omitted), and each signal contact 50 The tail portion 52 of () is soldered to a circuit pattern (not shown) on the circuit board CB.

The tail portion 42 of the ground contact 40 and the tail portion 52 of the signal contact 50 are formed at the end opposite to the position shown, or the tail portion 42 and the tail portion 52 are the same. You may provide in the edge part of a side. The tail portion 42 and the tail portion 52 may be formed at both ends of the ground contact 40 and the signal contact 50.

The actuator 60, which is an injection-molded member of heat-resistant synthetic resin material, has a pair of side pieces 62 extending from both sides of the operation handle 61 and the lower surface of the operation handle 61 constituting the upper portion, The pressing part 63 which hangs from the lower surface of the action handle 61, and comprises the recessed groove 64 (refer FIG. 8, FIG. 13) between the both ends and the left and right side pieces 62 is provided. On the outer side surface of the side piece 62, the upper protrusion part 65 and the lower protrusion part 66 are provided so that each may protrude. The engaging recess 67 is recessed in the rear of the pressing section 63 over its entire length. In the front part of the operation knob 61, the recessed concave part 69 whose both left and right sides are continuous with the inner side of the side piece 62, and the front side is continuous with the front surface of the press part 63 is made concave. In addition, five pressing grooves 71 extending in the upward direction from the lower end of the pressing portion 63 to the front of the pressing portion 63 are made concave.

The actuator 60 inserts the left and right side pieces 62 into the left and right insertion grooves 21, and elastically deforms the upper side piece 62 and the lower protrusion 66 of the actuator support 22 to the left and right lower protrusions. The 66 is placed in the locking recess 23 and the lower end of the pressing portion 63 is positioned above the inner space of the insulator 20 so as to be attached to and detached from the insulator 20.

When the left and right lower protrusions 66 are caught by the lower surface of the upper part of the left and right actuator support portions 22, the actuators 60 are located at the unpressed positions shown in Figs. 1 and 3 to 13. When the actuator 60 is positioned at the non-pressed position, the actuator 60 engages the engagement recesses 67 shown in FIGS. 3 to 13 at the upper end portions of the indentation portions 43 of the ground contact 40, respectively. At the same time, the upper part of the actuator support part 22 can be inserted into the upper protrusion 65 and the lower protrusion 66 so as to be kept inclined backward with respect to the insulator 20. In addition, although not shown, the insulator ( It is also possible to parallel with 20).

The actuator 60 is moved downward from the position where the actuator 60 is not pressed so as to elastically deform the upper side piece 62 and the left and right upper protrusions 65 of the actuator support part 22 and the left and right upper protrusions 65. ), The actuator 60 is located between the front wall 27 and the partition wall 29 (between the first elastic deformation portion 44 and the second elastic deformation portion 46). At the same time, the left and right concave grooves 64 of the actuator 60 are engaged with the left and right side walls 24, and a portion located immediately above the left and right concave grooves 64 is engaged with the left and right concave portions 25. Moreover, the partition wall 29 is located in the pressing position (position of FIG. 14-FIG. 17) engaged with the engagement recessed part 67. As shown in FIG. When located in the pressing position, the lower surface of the rear surface of the manipulation handle 61 is in contact with the upper surface of the rear wall 28, and the upper surface of the manipulation handle 61 is located at the same height as the upper surface of the front wall 27.

Next, the method of connecting the FFC 100 to the connector 10 will be described.

In order to connect the FFC 100 to the connector 10, as shown in FIG. 1, the actuator 60 is located in a position which is not pressed while inclining backward with respect to the insulator 20. As shown in FIG. 3 to 8, one end of the FFC 100 is inclined with respect to the vertical direction while being positioned directly in front of the actuator 60, and more than the engaging protrusion 101 of the end of the FFC 100. The upwardly positioned portion is positioned in the accommodating recess 69, and the left and right engagement protrusions 101 of the FFC 100 are positioned immediately above the left and right sidewalls 24, respectively. (See FIG. 8)

Subsequently, the FFC 100 is moved downward in the states of FIGS. 3 to 8. Then, the left and right engagement protrusions as shown in FIGS. 9 to 13 because the left and right engagement protrusions 101 cross the corresponding temporary fixed protrusions 35 downward by the elastic deformation of the end of the FFC 100. 101 moves immediately below the left and right temporary projections 35. Then, the relative movement of the actuator 60 upward with respect to the insulator 20 with respect to the engagement protrusion 101 and the temporary fixed protrusion 35 is regulated, and the end of the FFC 100 is parallel to the vertical direction. do. 11, the FFC 100 is bent. As shown in FIG. 12, an end portion of the FFC 100 is positioned between the first elastic deformation portion 44 and the second elastic deformation portion 46 of each ground contact 40.

Subsequently, when the actuator 60 is moved downward while being parallel with the up and down direction, the actuator 60 moves to the pressing position shown in FIGS. 14 to 17. Then, as shown in FIG. 16, the contact projections 55 and the FFCs of the respective signal contacts 50 are located between the partition wall 29 and the FFC 100 and the pressing unit 63 pushes the FFC 100 forward. Each signal line S of (100) is in contact with a high contact pressure. In addition, as shown in FIG. 17, an end portion of the FFC 100 is positioned between the second elastic deformation portion 46 and the partition wall 29 of each ground contact 40, and the pressing groove 71 of the pressing portion 63 is positioned. The second elastic deformation portion 46 of the ground contact 40 corresponding thereto is located. Thus, since the bottom (back) of each pressing groove 71 presses the corresponding second elastic deformation portion 46 toward the first elastic deformation portion 44, the contact protrusion 47 of the second elastic deformation portion 46 is performed. ) Contacts the ground layer GL of the FFC 100, the contact protrusion 45 of the first elastic deformation part 44 contacts each ground line of the FFC 100, and the FFC (not shown) The other end of 100 is also connected to the connector (same structure as the connector 10) facing in the same direction as the connector 10 arranged in the vicinity of the connector 10 shown in the same manner.

When the actuator 60 is returned to the non-pressed position, both ends of the FFC 100 can be removed from each connector 10. When the pair of connectors 10 are electrically connected through the FFC 100 as described above, the patterns of the circuit boards CB fixed to the two connectors 10 are connected to the signal contacts 50 of the respective connectors 10. And electrically connect each other through the signal line S of the FFC 100, and the high frequency signal is differentially transmitted by the pair of signal lines S and the signal contact 50. FIG.

Then, two sets of signal lines S are fitted on one side of the FFC 100 so that the round line G is provided, and the other side of the FFC 100 is covered with the ground layer GL. Further, the first elastic deformation portion 44 (contact protrusion 45) and the second elastic deformation portion 46 (contact protrusion 47) of each ground contact 40 are connected to the ground line G of the FFC 100. ) And the ground layer GL, respectively, are grounded to the ground pattern G of the circuit board CB fixed to the respective connectors 10 by the ground line G and the ground layer GL of the FFC 100. For this reason, crosstalk between each pair of signal lines S is reduced by the ground line G, and external noise extends to each signal line S from the other side of the FFC 100, or The ground layer GL prevents leakage of internal noise generated in the signal line S and the ground line G to the outside of the connector 10. As described above, the connector 10 and the FFC 100 can transmit the high frequency signals flowing through the signal contacts 50 and the signal lines S at high speed because they are devised in terms of crosstalk and noise.

In addition, the FFC 100 is manufacturable and inexpensive because the ground layer GL and each ground line G are not continuous with each other. Therefore, it is possible to lower the manufacturing cost of the entire apparatus including the FFC 100 and the connector 10 (and the circuit board CB).

In the present embodiment, the holding means, the temporary fixing protrusion 35, and the engaging protrusion 101 for preventing the end of the FFC 100 from being pulled out of the insulator 20 are provided in the FFC 100 and the insulator 20. Since it is provided, it is possible to connect the edge part of the FFC 100 and the connector 10 easily.

In addition, since the contact pressure between the ground contact 40 and the signal contact 50 and the FFC 100 is increased by the actuator 60, it is possible to reliably transmit each signal.

As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this embodiment, It can implement, carrying out various deformation | transformation.

For example, in the above embodiment, the holding means between the FFC 100 and the insulator 20 is constituted by the temporary fixed protrusion 35 of the insulator 20 and the engaging protrusion 101 of the FFC 100. And the protrusions which engage with the recesses formed on the FFC 100 side and the recesses formed on the insulator 20 side. In addition, the protrusion formed in the FFC 100 or the insulator 20 may be made of an elastic metal.

In addition, when inserting the actuator 60 to the pressing position, the pressing portion 63 is brought into contact with any one of the ground contact 40, the signal contact 50, and the FFC 100, so that the ground contact 40 The contact pressure between the FFC 100 and the contact pressure between the signal contact 50 and the FFC 100 may be increased. The actuator may also be a rotary actuator rotatable relative to the insulator 20.

In addition, the distance between the contact protrusion 45 and the contact protrusion 47 of the ground contact 40 in the free state is made narrower than the thickness of the FFC 100, and the FFC 100 is inserted by the clamping force when the FFC 100 is inserted. 100) may be prevented from being pulled out. At this time, the distance between the contact protrusions 55 of the signal contacts 10 is also narrower than the thickness of the FFC 100 so that the actuator is omitted, so that the contact conduction can be obtained only by the insertion of the FFC 100. It can be done with a connector.

In addition, it is also possible to use a thing other than FFC, for example, FPC (Flexible Printed Circuit) as a flat contact object. In this case, the signal line (S) and the ground line (G) are exposed on one side of the FPC, and the ground layer (GL) is formed on the other side, and the signal line (S) and the ground line (G) It is not continued with respect to the ground layer GL. In this case, the manufacturing cost is reduced by the FPC in which the signal line S and the ground line G are electrically connected to the ground layer GL. In addition, since the FPC does not have fine bumps and through holes inside, the FPCs do not cause a poor conduction due to disconnection of the bumps and through holes even after repeated bending. In addition, the FPC can be miniaturized since the dead space is smaller than that of the FPC having bumps and through holes. For this reason, the connector which is a connection partner can also be miniaturized.

Incidentally, the arrangement of the signal lines S and the ground lines G and the arrangement of the ground contacts 40 and the signal contacts 50 are not limited to the above-described embodiments, for example, the signal lines S and the ground lines ( G) and the ground contact 40 and the signal contact 50 may be alternately arranged one by one.

In addition, when the ground contact 40 is in the free state, the distance between the contact protrusion 45 of the first elastic deformation portion 44 and the contact protrusion 47 of the second elastic deformation portion 46 is set at the end of the connection object. Regardless of the plate thickness and the actuator is positioned at any position, the end of the connection object is inserted between the first elastic deformation portion 44 and the second elastic deformation portion 46 to allow the first elastic deformation portion 44 and the second elasticity. It is good also as a structure which the deformation | transformation part 46 electrically connects with a connection object.

The cell portion may be provided in the connector 10.

In addition, the direction at the time of using the connector 10 is not limited to the direction of the said embodiment, For example, as shown in FIG. 19, the FFC 100 (connection object) in the state which made the connector 10 a lateral direction. It is of course also possible to connect the ends of the.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view of the connector (actuator is located in the position which does not press) and FFC of embodiment of this invention.

2 is an exploded perspective view of a connector in which signal and ground contacts are omitted.

FIG. 3 is a perspective view of starting insertion while inclining the FFC to the connector in the position where the actuator is not pressed. FIG.

4 is a side view of the perspective view of FIG. 3.

5 is a front view of the perspective view of FIG. 3.

6 is a cross-sectional view taken along the line VI-VI of FIG. 5.

FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 5.

8 is a cross-sectional view taken along the line VIII-VIII of FIG. 5.

Fig. 9 is a perspective view when the FFC is vertically inserted by fully inserting the FFC into the connector at the position where the actuator is not pressed.

10 is a side view of the perspective view of FIG. 9.

FIG. 11 is a cross-sectional view corresponding to FIG. 6 in FIG. 9 perspective view.

12 is a cross-sectional view corresponding to FIG. 7 in FIG. 9 perspective view.

FIG. 13 is a cross-sectional view corresponding to FIG. 8 of FIG. 9, FIG.

14 is a perspective view of the connector and the FFC when the actuator is moved to the pressing position.

15 is a side view of the perspective view of FIG. 14.

16 is a cross-sectional view corresponding to FIG. 6 in FIG. 14 perspective view.

FIG. 17 is a cross-sectional view corresponding to FIG. 7 in FIG. 14 perspective view.

18 is a vertical side view of the FFC in which the middle part is omitted.

19 is a side view of the same shape as FIG. 15 of a modification.

<Description of the symbols for the main parts of the drawings>

10: connector 20: insulator

21: Insertion groove 22: Actuator support

23: locking recess 25: recessed portion

27: front wall 28: rear wall

29: partition wall 31: fixing groove

32: deformation allowance groove 34: engagement protrusion insertion groove

35: temporary fixing protrusion (holding means) 40: ground contact

41: horizontal portion 42: tail portion

43: press-fitting part 44: first elastic deformation part (contact part)

45: contact protrusion (contact part) 46: second elastic deformation part (contact part)

47: contact protrusion (contact part) 50: signal contact

51: horizontal portion 52: tail portion

53: press-fitting part 54: elastic deformation part (contact part)

55: contact protrusion (contact part) 60: actuator

61: operation handle 62: side

63: pressing unit 64: recessed groove

65: upper projection 6 66: lower projection

67: engagement recess 69

71: pressing groove

100: FFC (Flexible Flat Cable) (Connection Object)

101: engaging protrusion (holding means) 102: base material

103: cover layer 104: cover layer

105: end stiffener CB: circuit board

G: Ground Line GL: Ground Floor

S: signal line

Claims (3)

An insulator having a signal line and a ground line on one side and a flat plate-like connection object formed with a ground layer that is not continuous with the ground line on the other side; A signal contact supported by the insulator and having a contact portion electrically contacting with the signal line, And a ground contact supported by the insulator having a first elastic deformation portion and a second elastic deformation portion which sandwich the connecting object and form a two-contact contact while respectively contacting the ground line and the ground layer to be electrically conductive. And a connector. The method of claim 1, By contacting at least one of the said connection object, a signal contact, and a ground contact, the said insulator supports the actuator which raises at least one of the contact pressure between the said connection object and a signal contact, and the contact pressure between the said connection object and a ground contact. One connector. 3. The method of claim 2, And a retaining means formed between the insulator and the actuator so as to engage the connection object inserted in the insulator to restrict the movement of the connection object in the releasing direction.

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