JP2018206512A - connector - Google Patents

Abstract

To provide a connector which can prevent the erroneous insertion of a terminal, and can improve the strength of a housing while downsizing the housing.SOLUTION: A connector 1 is equipped with a housing 5 provided with a terminal storage chamber 3; a terminal 9; a locking lance 13; and a finger putting part 15 operated when fitting the housing 5 or separating the fitting of the housing 5. In the connector 1, on an outer peripheral wall 11 of the housing 5, a thin wall portion 17 is provided. On an outer surface of the thin wall portion 17, a reinforcing rib 19 is provided, which is raised from the outer surface of the thin wall portion 17 toward the outside of the housing 5 and is extended from the finger putting portion 15 toward the locking lance 13 side. On an inner surface of the thin wall portion 17, an erroneous insertion preventive rib 21 is disposed, which is raised from the inner surface of the thin wall portion 17 toward the inside of the housing, is extended from the locking lance 13 toward an insertion opening 7 side, permits the insertion of the terminal 9 into the storage chamber 3 in a normal insertion state of the terminal 9, and prevents the insertion of the terminal 9 into the terminal storage chamber 3 in a subnormal state of the terminal 9.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a connector.

  Conventionally, as a connector, a housing provided with a terminal accommodating chamber, a terminal accommodated in the terminal accommodating chamber through an insertion opening on one side of the housing, and a flexure provided in the terminal accommodating chamber from the inner surface of the outer peripheral wall of the housing. A locking lance that locks the terminal, and a finger rest that is arranged on the insertion opening side and is erected from the outer surface of the outer peripheral wall of the housing toward the outside of the housing and is operated when the housing is fitted and detached. (For example, refer to Patent Document 1).

  In this connector, in order to prevent damage to the finger rest when the housing is fitted and detached, the finger is erected on the outer surface of the outer peripheral wall of the housing from the outer surface of the thin wall portion toward the outer side of the housing. Reinforcing ribs extending from the abutting portion toward the locking lance are disposed.

JP 2003-7387 A

  By the way, in the connector like the said patent document 1, there was no structure which prevents incorrect insertion of the terminal in a terminal accommodating chamber in a housing, and there existed a possibility that a terminal might be inserted in the terminal accommodating chamber in the incorrect attitude | position.

  On the other hand, in the connector as described in Patent Document 1, the outer peripheral wall of the housing may be formed thin to reduce the size of the housing.

  In such a connector with a thin outer peripheral wall of the housing, reinforcing ribs are provided on the outer peripheral wall of the housing to prevent the finger rest from being damaged. However, the strength of the housing can be maintained only by the reinforcing ribs. There was a fear that I could not.

  Accordingly, an object of the present invention is to provide a connector that can prevent erroneous insertion of a terminal, and that can improve the strength of the housing while reducing the size of the housing.

  The invention according to claim 1 is a housing provided with a terminal accommodating chamber, a terminal accommodated in the terminal accommodating chamber from an insertion opening on one side of the housing, and an inner surface of an outer peripheral wall of the housing from the inner surface of the terminal accommodating chamber. A locking lance that is provided so as to be able to bend, and is arranged on the insertion opening side so as to be erected from the outer surface of the outer peripheral wall of the housing toward the outside of the housing. A finger rest that is operated at the time of mating and disengagement, a thin portion that is provided on the outer peripheral wall of the housing where the locking lance is located, and that is thinner than the other outer peripheral wall of the housing, and an outer surface of the thin portion A reinforcing rib that is arranged and is erected from the outer surface of the thin portion toward the outside of the housing and extends from the finger rest portion toward the locking lance side; and an inner surface of the thin portion that is disposed on the inner surface of the thin portion. Standing from the inner surface of the housing toward the inside of the housing and extending from the locking lance toward the insertion opening, allowing the terminal to be inserted into the terminal receiving chamber when the terminal is properly inserted. A connector having an erroneous insertion preventing rib for preventing the terminal from being inserted into the terminal accommodating chamber when the terminal is not properly inserted.

  In this connector, since the thin wall portion formed thinner than the other outer peripheral wall of the housing is provided on the outer peripheral wall of the housing where the locking lance is located, the housing can be reduced in size.

  In addition, the outer surface of the thin portion is provided with reinforcing ribs that are erected from the outer surface of the thin portion toward the outside of the housing and extend from the finger rest portion toward the locking lance. The strength of the finger rest that is operated at the time of fitting and at the time of disengagement can be improved, and breakage of the finger rest can be prevented.

  In addition, since the reinforcing rib extends from the finger rest portion toward the locking lance on the outer surface of the thin portion, the strength of the thin portion can be improved by the reinforcing rib.

  In addition, on the inner surface of the thin wall portion, there is an erroneous insertion prevention rib that allows the terminal to be inserted into the terminal accommodating chamber when the terminal is properly inserted and prevents the terminal from being inserted into the terminal accommodating chamber when the terminal is not properly inserted. Therefore, it is possible to prevent erroneous insertion of the terminal into the terminal accommodating chamber.

  In addition, since the erroneous insertion prevention rib is erected from the inner surface of the thin portion toward the inside of the housing and extends from the locking lance toward the insertion opening, the strength of the thin portion is reduced by the erroneous insertion prevention rib. Can be improved.

  Therefore, in such a connector, since the reinforcing rib is provided on the outer surface of the thin portion and the erroneous insertion preventing rib is provided on the inner surface of the thin portion, the erroneous insertion of the terminal can be prevented, and the housing can be downsized. However, the strength of the housing can be improved.

  The invention according to claim 2 is the connector according to claim 1, wherein the reinforcing rib and the erroneous insertion preventing rib are arranged so as to overlap each other with the thin portion interposed therebetween.

  In this connector, since the reinforcing rib and the erroneous insertion preventing rib are arranged so as to overlap each other with the thin portion interposed therebetween, the strength of the thin portion can be further improved.

  According to the present invention, it is possible to provide a connector that can prevent erroneous insertion of a terminal and that can improve the strength of the housing while reducing the size of the housing.

1 is an exploded perspective view of a connector according to a first embodiment of the present invention. It is sectional drawing of the connector which concerns on 1st Embodiment of this invention. It is a front view of the housing of the connector concerning a 1st embodiment of the present invention. It is a side view of the housing of the connector concerning a 1st embodiment of the present invention. It is a bottom view of the housing of the connector concerning a 1st embodiment of the present invention. It is sectional drawing of the housing of the connector which concerns on 1st Embodiment of this invention. It is a perspective view of the terminal of the connector concerning a 1st embodiment of the present invention. It is sectional drawing when a terminal is inserted in the housing of the connector which concerns on 1st Embodiment of this invention in the irregular insertion state. It is sectional drawing of the housing of the connector which concerns on 2nd Embodiment of this invention.

  A connector according to an embodiment of the present invention will be described with reference to FIGS.

(First embodiment)
The first embodiment will be described with reference to FIGS.

  The connector 1 according to the present embodiment includes a housing 5 provided with a terminal accommodating chamber 3, a terminal 9 accommodated in the terminal accommodating chamber 3 from an insertion opening 7 on one side of the housing 5, and an outer peripheral wall 11 of the housing 5. A locking lance 13 that is provided in the terminal accommodating chamber 3 so as to be bent from the inner surface of the housing 5 and that locks the terminal 9. And a finger rest 15 that is erected and operated when the housing 5 is fitted and detached.

  In addition, the outer peripheral wall 11 of the housing 5 where the locking lance 13 is located is provided with a thin portion 17 formed thinner than the other outer peripheral walls of the housing 5.

  Further, on the outer surface of the thin portion 17, a reinforcing rib 19 is disposed so as to stand from the outer surface of the thin portion 17 toward the outside of the housing 5 and extend from the finger rest portion 15 toward the locking lance 13. ing.

  The inner surface of the thin portion 17 is erected from the inner surface of the thin portion 17 toward the inside of the housing 5 and extends from the locking lance 13 toward the insertion opening 7 so that the terminal 9 is in a properly inserted state. An erroneous insertion preventing rib 21 that allows insertion of the terminal 9 into the storage chamber 3 and prevents the terminal 9 from being inserted into the terminal storage chamber 3 when the terminal 9 is not properly inserted is disposed.

  As shown in FIGS. 1-8, the housing 5 consists of insulating materials, such as a synthetic resin, and can be fitted with the other party housing (not shown).

  The housing 5 is provided with a lock arm 25 having a lock portion 23 that holds the mating state with the mating housing so as to be able to bend, and the lock portion 23 is engaged with a locked portion (not shown) provided on the mating housing. By fitting, the mating state between the mating housing and the housing 5 is maintained.

  An operation unit 27 is provided on the free end side of the lock arm 25. By pressing the operation unit 27, the lock arm 25 is bent, and the engagement between the lock unit 23 and the locked unit is released. The mating state between the mating housing and the housing 5 can be released.

  Such a housing 5 is provided with a plurality of terminal accommodating chambers 3 and is accommodated in a plurality of mating terminals (not shown) accommodated in the mating housing and a plurality of terminal accommodating chambers 3 by fitting with the mating housing. The plurality of terminals 9 are electrically connected.

  The terminal accommodating chamber 3 is formed inside the housing 5 along the length direction of the housing 5, and a plurality (three in this case) are arranged in parallel in the width direction of the housing 5.

  In this terminal accommodating chamber 3, one end side in the length direction is an insertion opening 7 into which the terminal 9 is inserted, and the other end side in the length direction is a male terminal of a mating terminal connected to the terminal 9 accommodated therein. A connection opening 29 into which a tab-like connection portion (not shown) of the mold is inserted is formed.

  In the plurality of terminal accommodating chambers 3, a plurality of terminals 9 are accommodated from the insertion openings 7 on one end side in the length direction.

  The terminal 9 is formed of a single member in which the wire connecting portion 31 and the terminal connecting portion 33 are continuous by performing punching or bending on a single plate material made of a conductive material.

  The wire connection portion 31 includes a covering crimping portion 35 and a core wire crimping portion 37.

  The covering crimping portion 35 is composed of a pair of crimping pieces, and crimps the covering portion of the electric wire 39 at the terminal portion of the electric wire 39 connected to a power source or equipment.

  The terminal 9 is fixed to the electric wire 39 by crimping the covering crimp portion 35 to the covering portion of the electric wire 39.

  The core wire crimping portion 37 is composed of a pair of crimping pieces provided between the terminal connecting portion 33 and the covering crimping portion 35, and caulking the core wire portion exposed from the covering portion of the electric wire 39 at the terminal portion of the electric wire 39. And crimped.

  The terminal 9 is electrically connected to the electric wire 39 by crimping the core wire crimping portion 37 to the core wire portion of the electric wire 39.

  The terminal connection portion 33 is formed of a single member whose bottom wall is continuous with the wire connection portion 31, and is formed of a female connection portion formed in a box shape by bending both side walls and the upper wall.

  An elastic piece (not shown) having a contact portion (not shown) on the free end side as one member continuous with the terminal connection portion 33 is elastically deformed inside the terminal connection portion 33 so as to have a predetermined urging force. It is provided as possible.

  In such a terminal connection portion 33, an opening is provided on one end side in the length direction, and a tab-like connection portion of the mating terminal is inserted into the inside from this opening, and the contact portion is tab-shaped by the urging force of the elastic piece. The terminal 9 and the mating terminal are electrically connected by contact with the connecting portion.

  The terminal 9 having such a box-shaped terminal connecting portion 33 is connected to the terminal portion of the electric wire 39 via the electric wire connecting portion 31 and is inserted into the terminal accommodating chamber 3 from the insertion opening 7 of the terminal accommodating chamber 3. The electric wire 39 is drawn out from the insertion opening 7 to the outside of the housing 5.

  Thus, the terminal 9 accommodated in the terminal accommodating chamber 3 is locked by a locking lance 13 provided in the terminal accommodating chamber 3, thereby preventing the terminal accommodating chamber 3 from coming off from the insertion opening 7. The

  The terminal 9 is inserted into the terminal accommodating chamber 3 by bringing the end face of the terminal connecting portion 33 of the terminal 9 into contact with the wall portion provided with the connection opening 29 of the terminal accommodating chamber 3. Further insertion of the terminal 9 is restricted.

  The locking lance 13 is formed of one member whose base end side is continuous with the inner surface of the outer peripheral wall 11 that is the bottom wall of the terminal accommodating chamber 3, and whose free end side is inclined toward the inside of the terminal accommodating chamber 3, The terminal housing chamber 3 is provided so as to be able to bend in the vertical direction.

  On the free end side of the locking lance 13, a locking portion 41 is protruded toward the inside of the terminal accommodating chamber 3 by one member continuous with the locking lance 13.

  When the terminal 9 is inserted from the insertion opening 7 of the terminal accommodating chamber 3, the locking portion 41 slides with the terminal connecting portion 33 and bends the locking lance 13 downward (outer peripheral wall 11 side). .

  The bent locking lance 13 is restored upward (inside the terminal accommodating chamber 3) when the terminal connecting portion 33 is disposed at the normal position of the terminal accommodating chamber 3, and the engaging portion 41 is Inserted into the hole 43 of the terminal connecting portion 33, the locking portion 41 is disposed so as to be engageable with the locking projection 45.

  A release wall 47 is extended from the base end side of the locking portion 41 in the protruding direction toward the connection opening 29 by a member continuous with the locking lance 13, and a release jig ( The terminal 9 can be pulled out from the insertion opening 7 of the terminal accommodating chamber 3 by abutting (not shown) and bending the locking lance 13.

  The hole 43 is provided on the upper wall of the terminal connection portion 33 facing the locking lance 13 and is a rectangular hole penetrating the upper wall. When the locking lance 13 is restored, the hole 43 is locked. The part 41 can be inserted.

  The locking projection 45 is disposed at the edge of the hole 43 at one end in the length direction, and protrudes from the upper wall of the terminal connection portion 33 toward the locking lance 13.

  This locking projection 45 can be engaged in the direction in which the locking portion 41 and the terminal 9 are detached from the terminal accommodating chamber 3 in a state where the locking lance 13 is restored and the locking portion 41 is inserted into the hole 43. Placed in.

  By disposing the locking projection 45 so as to be engageable with the locking portion 41 in this way, when a tensile force is applied to the electric wire 39, the locking projection 45 and the locking portion 41 are engaged, and the terminal is accommodated. The terminal 9 can be prevented from coming off from the chamber 3.

  The outer peripheral wall 11 of the housing 5 provided with the locking lance 13 for locking the terminal 9 is provided with a finger pad 15 that is operated when the housing 5 is fitted and detached.

  The finger pad 15 is disposed on the side of the insertion opening 7 of the outer peripheral wall 11 of the housing 5, and is a single member that continues from the outer surface of the outer peripheral wall 11 of the housing 5 and stands toward the outside of the housing 5 over the width direction of the housing 5. It is installed.

  When the housing 5 is fitted to the mating housing, the finger rest 15 is pressed against the operator's finger from the insertion opening 7 side toward the connection opening 29 side. And are fitted.

  On the other hand, when the fitting between the housing 5 and the mating housing is released, the finger rest 15 is brought into contact with the operator's finger and pressed from the connection opening 29 side toward the insertion opening 7 side. 5 is released from the mating housing.

  A thin-walled portion 17 is provided on the outer peripheral wall 11 of the housing 5 provided with such a finger pad portion 15.

  The thin portion 17 is provided on the outer peripheral wall 11 where the locking lance 13 is located in the outer peripheral wall of the housing 5, and is formed thinner than the other outer peripheral walls.

  Thus, by providing the thin wall portion 17 on the outer peripheral wall 11 of the housing 5, the housing 5 can be downsized in the height direction.

  However, if the thin wall portion 17 is provided on the outer peripheral wall 11 provided with the finger rest 15, the strength of the finger rest 15 is reduced, and the finger rest is caused by the operation when the housing 5 is fitted and detached. There was a possibility that the portion 15 was damaged.

  Therefore, reinforcing ribs 19 are provided on the outer peripheral wall 11 of the housing 5.

  A plurality (three in this case) of the reinforcing ribs 19 are arranged on the outer peripheral wall 11 of the housing 5, and are erected from the finger rest 15 in a single member continuous from the outer surface of the thin portion 17 toward the outside of the housing 5. It extends toward the stop lance 13 side.

  By providing the reinforcing rib 19 in this manner, the strength of the finger pad 15 can be improved, and the finger pad 15 can be prevented from being damaged by the operation when the housing 5 is fitted and detached.

  In addition, the reinforcing rib 19 is a single member continuous from the outer surface of the thin portion 17 and is erected toward the outside of the housing 5 and extends from the finger rest 15 toward the locking lance 13. The strength of the thin portion 17 can be improved, and the strength of the housing 5 can be improved while downsizing the housing 5.

  Furthermore, by providing the reinforcing rib 19, the fluidity of the resin at the time of molding the housing 5 is improved, and the productivity of the housing 5 can be improved.

  Here, the terminal 9 accommodated in the terminal accommodating chamber 3 is provided with a locking projection 45 that can be engaged with the locking portion 41 of the locking lance 13.

  When the terminal 9 is inserted into the insertion opening 7, the locking protrusion 45 is the locking protrusion 45 if the locking protrusion 45 is in the normal insertion state of the terminal 9 in a posture facing the locking lance 13 side. And the locking portion 41 can be engaged, and the terminal 9 can be locked in the terminal accommodating chamber 3.

  However, when the terminal 9 is inserted into the insertion opening 7, if the terminal 9 is in an irregularly inserted state in which the locking protrusion 45 does not face the locking lance 13, the locking protrusion 45 and the locking protrusion 45 are locked. The portion 41 cannot be engaged, and the terminal 9 cannot be locked in the terminal accommodating chamber 3.

  Therefore, an erroneous insertion preventing rib 21 for preventing erroneous insertion of the terminal 9 is provided in the terminal accommodating chamber 3.

  The erroneous insertion preventing ribs 21 are arranged on both sides of the locking lance 13 in the width direction, and are erected toward the inside of the housing 5 with one member continuous from the inner surface of the thin portion 17, from the locking lance 13 to the insertion opening 7 side. It is extended toward.

  When the terminal connection portion 33 is inserted from the insertion opening 7 between the erroneous insertion preventing ribs 21 and 21 provided on both sides of the locking lance 13, the locking projection 45 is engaged. A groove portion 49 is provided to guide the guide to the locking portion 41.

  Such an erroneous insertion prevention rib 21 allows the insertion of the terminal 9 into the terminal accommodating chamber 3 when the terminal 9 is inserted in the normal insertion state from the insertion opening 7 and the groove portion 49 engages with the locking projection 45. Then, the locking projection 45 and the locking portion 41 can be engaged (see FIG. 2).

  On the other hand, the erroneous insertion preventing rib 21 prevents the terminal 9 from being inserted into the terminal accommodating chamber 3 by abutting against the terminal connecting portion 33 when the terminal 9 is inserted in an irregularly inserted state from the insertion opening 7. Can be detected as an irregular insertion state (see FIG. 8).

  By providing the erroneous insertion preventing rib 21 in this manner, the erroneous insertion of the terminal 9 into the terminal accommodating chamber 3 can be prevented, and the terminal 9 can be stably held in the terminal accommodating chamber 3.

  In addition, the erroneous insertion prevention rib 21 is a single member continuous from the inner surface of the thin portion 17 and is erected toward the inside of the housing 5 and extends from the locking lance 13 toward the insertion opening 7. In addition to the reinforcing rib 19, the strength of the thin portion 17 can be further improved, and the strength of the housing 5 can be further improved while downsizing the housing 5.

  Furthermore, by providing the erroneous insertion preventing rib 21 in addition to the reinforcing rib 19, the fluidity of the resin when the housing 5 is molded can be further improved, and the productivity of the housing 5 can be further improved.

  In such a connector 1, the outer peripheral wall 11 of the housing 5 where the locking lance 13 is located is provided with the thin portion 17 formed thinner than the other outer peripheral wall of the housing 5. can do.

  A reinforcing rib 19 is disposed on the outer surface of the thin portion 17 so as to stand from the outer surface of the thin portion 17 toward the outside of the housing 5 and extend from the finger rest 15 toward the locking lance 13. Therefore, the strength of the finger pad 15 that is operated when the housing 5 is fitted and detached can be improved, and damage to the finger pad 15 can be prevented.

  In addition, since the reinforcing rib 19 extends from the finger rest 15 toward the locking lance 13 on the outer surface of the thin portion 17, the strength of the thin portion 17 can be improved by the reinforcing rib 19. .

  Further, on the inner surface of the thin portion 17, the terminal 9 is allowed to be inserted into the terminal accommodating chamber 3 when the terminal 9 is properly inserted, and the terminal 9 is prevented from being inserted into the terminal accommodating chamber 3 when the terminal 9 is not properly inserted. Since the erroneous insertion preventing rib 21 is disposed, the erroneous insertion of the terminal 9 into the terminal accommodating chamber 3 can be prevented.

  In addition, the erroneous insertion prevention rib 21 is erected from the inner surface of the thin portion 17 toward the inside of the housing 5 and extends from the locking lance 13 toward the insertion opening 7. 21 can improve the strength of the thin portion 17.

  Therefore, in such a connector 1, the reinforcing rib 19 is provided on the outer surface of the thin portion 17, and the erroneous insertion preventing rib 21 is provided on the inner surface of the thin portion 17. In addition, the strength of the housing 5 can be improved while reducing the size of the housing 5.

(Second Embodiment)
The second embodiment will be described with reference to FIG.

  In the connector 101 according to the present embodiment, the reinforcing rib 19 and the erroneous insertion preventing rib 21 are arranged so as to overlap each other with the thin portion 17 interposed therebetween.

  In addition, although the same code | symbol is described to the structure same as 1st Embodiment, description is abbreviate | omitted, but since it is the same structure as 1st Embodiment, a structure and functional description refer to 1st Embodiment. Although omitted, the obtained effects are the same.

  As shown in FIG. 9, the reinforcing rib 19 is located on the side of the locking lance 13 so as to overlap the insertion opening 7 side of the erroneous insertion preventing rib 21 with the thin portion 17 interposed therebetween when viewed from the height direction of the housing 5. It is extended toward.

  Thus, by arranging the reinforcing rib 19 and the erroneous insertion preventing rib 21 so as to overlap each other with the thin portion 17 interposed therebetween, the strength of the thin portion 17 can be further improved, and the strength of the housing 5 is further improved. be able to.

  In addition, by extending the reinforcing rib 19 toward the locking lance 13 side, the fluidity of the resin when the housing 5 is molded can be further improved, and the productivity of the housing 5 can be further improved.

  In such a connector 101, since the reinforcing rib 19 and the erroneous insertion preventing rib 21 are disposed so as to overlap each other with the thin portion 17 interposed therebetween, the strength of the thin portion 17 can be further improved.

  In the connector according to the embodiment of the present invention, the reinforcing rib and the erroneous insertion preventing rib are arranged so as to overlap each other by extending the reinforcing rib toward the locking lance side. Alternatively, the erroneous insertion preventing rib may be extended toward the insertion opening side, and the reinforcing rib and the erroneous insertion preventing rib may be overlapped.

  In this case, since the erroneous insertion preventing rib is disposed on the finger contact portion side, the strength of the finger contact portion can be further improved, and damage to the finger contact portion can be further prevented.

DESCRIPTION OF SYMBOLS 1,101 ... Connector 3 ... Terminal accommodating chamber 5 ... Housing 7 ... Insertion opening 9 ... Terminal 11 ... Outer peripheral wall 13 ... Locking lance 15 ... Finger rest part 17 ... Thin part 19 ... Reinforcement rib 21 ... Misinsertion prevention rib 101 ... connector

Claims (2)

A housing provided with a terminal accommodating chamber;
A terminal accommodated in the terminal accommodating chamber from an insertion opening on one side of the housing;
A locking lance that is provided so as to be deflectable from the inner surface of the outer peripheral wall of the housing into the terminal accommodating chamber, and locks the terminal;
A finger rest that is arranged on the insertion opening side and is erected from the outer surface of the outer peripheral wall of the housing toward the outside of the housing and operated when the housing is fitted and detached.
A thin-walled portion formed on the outer peripheral wall of the housing where the locking lance is located and formed thinner than the other outer peripheral wall of the housing;
Reinforcing ribs arranged on the outer surface of the thin wall portion and erected from the outer surface of the thin wall portion toward the outside of the housing and extending from the finger rest portion toward the locking lance,
The terminal is disposed on the inner surface of the thin wall portion, is erected from the inner surface of the thin wall portion toward the inside of the housing, extends from the locking lance toward the insertion opening side, and accommodates the terminal in a properly inserted state of the terminal. An erroneous insertion preventing rib that allows the insertion of the terminal into a chamber and prevents the insertion of the terminal into the terminal accommodating chamber in an irregularly inserted state of the terminal;
A connector comprising: The connector according to claim 1,
The connector, wherein the reinforcing rib and the erroneous insertion preventing rib are arranged so as to overlap each other with the thin portion interposed therebetween.

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