JP3237834B2 - Flexible circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible circuit board (FPC), and more particularly to a flexible circuit board used for transmitting and receiving signals to and from a movable portion provided in a printer or the like.

[0002]

2. Description of the Related Art FIGS. 6 and 7 show a flexible circuit board A of this kind. This flexible circuit board A
Is a flexible sheet-shaped circuit board main body 4 in which a cover lay 3 that covers the circuit pattern 1 is laminated and integrated on a base film 2 in which a current path is formed by a plurality of linear circuit patterns 1; A reinforcing plate 5 joined to the back surface of the circuit board body 4 in an overlapping manner. The cover lay 3 is cut off at the end of the circuit board main body 4, and the circuit pattern 1
Are exposed to form an electrode pattern 6. The reinforcing plate 5 is joined to the back surface of the circuit board main body 4 so as to straddle the exposed portion of the electrode pattern 6 and the adjacent portion as shown in the drawing. Such a flexible circuit board A has a flexibility that allows the circuit board body 4 to withstand various forms of deformation such as bending deformation and twisting deformation, and is provided in a printer or the like by utilizing the flexibility. It is possible to absorb the movement of the movable part. Also, the reinforcing plate 5
Has an effect of backing up the exposed portion of the electrode pattern 6 so as not to bend.

[0003] The flexible circuit board A includes a reinforcing plate 5.
The exposed portion of the electrode pattern 6 backed by the above, that is, the end of the circuit board main body 4 is formed as an insertion piece 7, and the insertion piece 7 is inserted into a connector (not shown in FIGS. 6 and 7). The insertion piece 7 is fixed to the connector. Such a mode of use is illustrated in FIG.

In FIG. 8, reference numeral 8 denotes a flat wiring board (PCB) having a large bending strength, and a connector 9 is mounted on the wiring board 8. When the insertion piece 7 is inserted into the connector 9, a contact (not shown) elastically contacts the electrode pattern 6 of the insertion piece 7, and the circuit on the wiring board 8 side and the current path on the flexible circuit board A side are electrically connected. While being connected, the insertion piece 7 is fixed to the connector 9 by the resilient action of the contact. In this use mode, when the flexible circuit board A is connected to a movable portion of a printer (for example, a carriage of an ink cassette) or the like, the circuit board main body 4 frequently moves due to the flexibility due to its flexibility. While repeatedly bending and twisting, the reinforcing plate 5 of the circuit board body 4 is formed.
In the joint portion (1), bending and torsional deformation are prevented by the reinforcing action of the reinforcing plate 5, and the contact stability between the electrode pattern 6 and the contact on the connector 9 side and the connection stability with the connector 9 are maintained.

On the other hand, Japanese Utility Model Laid-Open Publication No. 59-111063 discloses that a reinforcing plate is provided on the back surface of a connecting end of a flexible circuit board via an elastic body, and the connecting end on which the reinforcing plate is provided is connected to a connector. It is described that it is inserted and fixed.

Japanese Unexamined Patent Publication (Kokai) No. 61-199690 discloses that one end of an insertion / removal jig made of a reinforcing plate is joined to a back portion of a flexible base member of a flexible circuit board, and is attached to the back portion. The other end of the unjoined insertion / removal jig can be grasped by a finger, and the other end of the insertion / removal jig is grasped by a finger, and the end of the flexible circuit board is inserted / removed from / to the connector. There is a description of a flexible circuit board that can be used.

Further, Japanese Patent No. 2534754 discloses that a connector base is interposed between a hard reinforcing plate fixed to one end of a flexible wiring sheet bent in a meandering shape and a printed board, and the connector base and the hard reinforcing plate are connected to each other. There is a description that a circuit terminal of a printed circuit board is connected to one end of a flexible wiring sheet by a conductive pin penetrating through, and the other end of the flexible wiring sheet is connected to another printed circuit board via a connector plug.

[0008]

In the conventional flexible circuit board A described with reference to FIGS. 6 to 8, a deformed portion a when the circuit board body 4 is deformed such as bending or twisting by being pulled is formed. 8, as shown by the imaginary line in FIG. 8, the curvature of the deformed portion a is located relatively close to the edge of the reinforcing plate 5 (in other words, the radius of the curved deformed portion a is small). ). this is,
One of the causes is that the bending strength of the joining region of the flat reinforcing plate 5 at the end of the circuit board body 4 is large, and the bending strength of the region adjacent to the joining region is extremely smaller than the bending strength of the joining region. It is supposed to be one.

Then, as described above, the circuit board body 4
If the situation where bending deformation and torsional deformation occur with a large curvature immediately near the edge of the reinforcing plate 5 is frequently repeated,
There is a possibility that the linear circuit pattern 1 forming the energizing path described with reference to FIG. Such a problem cannot be solved at all by the techniques described in the above publications.

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances, and determines the magnitude of the bending strength of a region (adjacent region) adjacent to a joining region of a reinforcing plate in a circuit board main body. By setting the size to an intermediate value between the above, the curvature when the adjacent region is deformed is reduced to some extent (that is, the radius of the curved deformed portion is increased), and the circuit pattern 1 caused by the deformation is reduced. An object of the present invention is to provide a flexible circuit board main body in which disconnection or the like is less likely to occur.

Further, the present invention provides a flexible circuit board capable of determining the magnitude of the bending strength of the adjacent region as described above without increasing the number of parts and the number of assembling steps by utilizing a reinforcing plate. The purpose is to:

Another object of the present invention is to provide a flexible circuit board capable of changing the magnitude of the bending strength of the adjacent region stepwise.

A flexible circuit board according to the present invention has a circuit board main body having a plurality of circuit patterns covered with an electrically insulating thin film, and the end portions of the plurality of circuit patterns are arranged on the end surface of the circuit board main body. an electrode pattern formed by exposed, and a reinforcing plate bonded to form an overlap on the back end of the circuit board body possess the said circuit board present
Insert that secures the end of the body by inserting it into the connector
In a flexible circuit board formed as
The flexible circuit board is connected to the movable part and
The flexible circuit board is reinforced as the part moves.
Deformation occurs in the adjacent area adjacent to the joint area of the plate
The reinforcing plate is joined to the back surface of the circuit board main body over the exposed portion of the electrode pattern and the adjacent portion thereof, and the circuit board is formed in the adjacent region starting from the edge of the reinforcing plate. A functional piece is integrally provided on the reinforcing plate so as to extend in a direction away from an end of the main body, and a plurality of transverse sections extending in a direction crossing the circuit board main body and the functional piece are connected to the transverse section. Having a connecting portion extending along the longitudinal direction of the circuit board main body, formed in a meandering shape by the traversing portion and the connecting portion, the mutual interval of each adjacent traversing portion is from the reinforcing plate. It gradually decreases in the direction of going away. Here, the functional piece has a function of setting the magnitude of the bending strength of the adjacent area to be intermediate between the magnitude of the bending strength of the bonding area of the reinforcing plate and the magnitude of the bending strength of the circuit board body. Therefore, the curvature when the circuit board main body is deformed in a curved shape in the adjacent area is suppressed to be small by the function of the functional piece, and the disconnection of the circuit pattern of the circuit board main body in the adjacent area hardly occurs.

In the flexible circuit board according to the present invention, the functional piece is integrally extended with the reinforcing plate.
Therefore, when the reinforcing plate is molded into a flat plate with a synthetic resin, the functional piece is integrally formed with the reinforcing plate at the same time, or when the reinforcing plate is joined to the circuit board body, the functional piece is joined to the circuit board body at the same time. Or become possible. Therefore, the number of parts and the number of assembly steps do not increase.

[0015] Further , the reinforcing plate may be provided with an exposed portion of the electrode pattern.
Of the circuit board main body over the output location and the adjacent location.
Adjoined to the back surface and adjacent to the joint area of the reinforcing plate
The circuit board body starting from the edge of the reinforcing plate in the region
Function piece so that it extends in the direction away from the end of the
ing.

According to this structure, the bending deformation of the electrode pattern is prevented by the reinforcing plate having a large bending strength, and the breakage of the circuit pattern in the region adjacent to the joining region of the reinforcing plate is more unlikely to occur. .

The above function of the functional piece, that is, the function that the magnitude of the bending strength of the adjacent area can be set to an intermediate value between the magnitude of the bending strength of the bonding area of the reinforcing plate and the magnitude of the bending strength of the circuit board main body is the same as the function. This is exhibited by appropriately selecting the shape of the piece and the bending strength of the functional piece itself. Regarding the shape of the functional piece, the functional piece has a traversing part extending along the direction traversing the circuit board body and a connecting part connected to the traversing part and extending along the longitudinal direction of the circuit board body. It is possible to select such a shape,
As a specific example, there can be cited one in which the functional piece is formed in a meandering shape by the traversing portion and the connecting portion.

The one in which the functional piece crosses the circuit board body
A plurality of traversing parts extending along the direction and connected to the traversing parts
A plurality of contacts extending along a longitudinal direction of the circuit board body;
And a meandering shape by the traversing part and the connecting part.
The adjacent rows are spaced from each other,
It gradually decreases in the direction away from the reinforcing plate
Thus, the magnitude of the bending strength in the adjacent region changes stepwise.

[0019]

1 to 4 are partial plan views of several different embodiments of a flexible circuit board A according to the present invention as viewed from the back side. The circuit board main body 4 of the flexible circuit board A shown in these figures has the same configuration as that described with reference to FIGS. FIG. 6 also shows the reinforcing plate 5.
Similarly to the case described with reference to FIGS. 7A and 7B, it is bonded to the back surface of the circuit board main body 4 with an adhesive over the exposed portion of the electrode pattern and the adjacent portion. The end of the circuit board main body 4 where the electrode pattern is exposed is formed as an insertion piece 7 inserted into a connector 9 mounted on a wiring board 8 described later (see FIG. 5). In FIGS. 1 to 4, the exposed portion of the electrode pattern at the end of the circuit board main body 4 is indicated by a reference symbol P.

In these flexible circuit boards A, the curvature when the circuit board body is deformed in a curved shape is large in a region (adjacent region) adjacent to the joining region of the reinforcing plate 5 with respect to the back surface of the circuit board body 4. The function piece 10 that restricts the occurrence is joined with an adhesive. This functional piece 10 is different for each flexible circuit board A in FIGS.

That is, each functional piece 10 shown in FIGS.
The reinforcing plate 5 is integrally formed with the reinforcing plate 5 in a thin plate shape using synthetic resin, and extends from the end edge 51 of the reinforcing plate 5 in a direction X away from the end of the circuit board body 4 over a predetermined length. It has been extended. Each of the functional pieces 10 includes a plurality of traversing portions 11 extending along the direction traversing the circuit board body 4 and a plurality of traversing portions 11 connected to the traversing portions 11 and extending along the longitudinal direction of the circuit board body 4. Although each of the functional pieces 10 shown in FIG. 1 and FIG. On the other hand, the functional piece 10 shown in FIG. 2 is different from the functional piece 10 in that a connecting portion 12 is continuously provided at the center of the traversing portion 11. Further, in the functional piece 10 shown in FIG. 1, the mutual spacing between the adjacent transverse portions 11 is uniform, whereas in the functional piece 10 shown in FIG. The interval between the portions 11 gradually decreases in the direction away from the reinforcing plate 5 (corresponding to the direction X away from the end of the circuit board body 4 described above).

On the other hand, the functional piece 10 shown in FIG. 4 is formed by a collection of individually independent strip-shaped strips arranged at predetermined intervals.

In each of the flexible circuit boards A shown in FIGS. 1 to 3, the functional piece 10 extends integrally with the reinforcing plate 5. Such a functional piece 10 is formed integrally at the same time when the reinforcing plate 5 is formed into a flat plate shape with a synthetic resin, and when the reinforcing plate 5 is joined to the circuit board main body 4 at the same time. Are joined.

Each of the functional pieces 10 shown in FIGS. 1 to 4 has a large bending strength in a region adjacent to the joint region of the reinforcing plate 5 with the back surface of the circuit board body 4 (adjacent region: joint region of the functional member 10). This helps to determine the midpoint between the joint area of the reinforcing plate 5 and the bending strength of the circuit board body 4. That is, in the functional piece 10 shown in FIGS. 1 to 3, even if it has the same thickness as the reinforcing plate 5, the shape is a meandering shape, or With such a shape, the bending strength of the functional piece 10 itself is smaller than the bending strength of the reinforcing plate 5, and such a functional piece 10 is joined to the circuit board body 4. The magnitude of the bending strength in the adjacent area is determined to be intermediate between the magnitude of the bending strength of the bonding area of the reinforcing plate 5 and the magnitude of the bending strength of the circuit board body 4.

FIG. 5 shows a state in which the insertion piece 7 of the flexible circuit board A shown in FIG. 1 or 3 is inserted into a connector 9 mounted on a wiring board 8 and fixed. In the state shown in the figure, for example, the flexible circuit board A is connected to a movable portion of a printer, and the adjacent region, that is, the joint region of the functional piece 10 is bent or twisted with the movement of the movable portion. When the deformation occurs, the curvature of the curved deformation portion a can be suppressed to a certain extent as compared with the conventional case described with reference to FIG. In other words, the radius of the curved deformed portion a is kept large. Therefore, disconnection of the circuit pattern due to the deformation of the circuit board main body 4 hardly occurs. In particular, the functional piece 1 shown in FIG.
If the distance between the adjacent traversing portions 11 is gradually reduced in the direction away from the reinforcing plate 5 as in 0, the curvature of each portion of the deformed portion changes in accordance with the distance between the traversing portions 11. Therefore, there is an advantage that it is possible to appropriately adjust the curvature in accordance with the location, such as making it difficult to bend the location where the bending force is most likely to concentrate. Such an advantage is not limited to the case where the mutual distance between the traversing portions 11 is gradually reduced in the direction away from the reinforcing plate 5, but is also exerted by increasing the mutual distance in the direction away from the reinforcing plate 5. You.

The function of suppressing the curvature of the curved deformed portion in the adjacent region to a certain extent as compared with the conventional case described with reference to FIG. 8 is also exerted by the functional piece 10 described with reference to FIG.

The shape of the functional piece 10 is not limited to that described with reference to FIGS. For example, the functional piece 10 is
In the case where the functional piece 10 is formed integrally with the reinforcing plate 5, the functional piece 10 may be formed as a flat plate having a thickness smaller than the thickness of the reinforcing plate 5 made of the same material. Further, the functional piece 10 may be a perforated plate, or may have a shape other than that shown in FIGS.

Although FIG. 5 shows a use mode in which the insertion piece 7 at the end of the circuit board body 4 is inserted into the connector 9 and fixed, the use mode of the flexible circuit board A is shown in FIG. It is not limited to one. For example, when a reinforcing plate is joined to an intermediate portion in the longitudinal direction of the flexible circuit board, and bending or twisting occurs in an area adjacent to the joining area of the reinforcing board, the function described above is applied to the area adjacent to the joining area. The pieces may be joined together.

In the functional piece 10 described with reference to FIGS. 2 and 3 as well, the mutual interval between the transverse portions 11 may be gradually reduced or increased in the direction away from the reinforcing plate 5. It is possible.

[0030]

As described above, according to the present invention, it is possible to provide a flexible circuit board main body in which disconnection or the like of a circuit pattern due to deformation hardly occurs. In particular, by extending the functional piece integrally with the reinforcing plate, it is possible to provide a flexible circuit board main body in which disconnection of a circuit pattern due to deformation is unlikely to occur without increasing the number of parts and the number of assembly steps. Become. Therefore, the occurrence of a situation in which the circuit pattern is disconnected due to the influence of the deformation such as the bending deformation or the torsional deformation of the circuit board body is significantly suppressed, and the connection reliability is greatly improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a partial plan view of an embodiment of a flexible circuit board according to the present invention as viewed from the back side.

FIG. 2 is a partial plan view of another embodiment of the flexible circuit board viewed from the back side.

FIG. 3 is a partial plan view of still another embodiment of the flexible circuit board viewed from the back surface side.

FIG. 4 is a partial plan view of still another embodiment of the flexible circuit board viewed from the back surface side.

FIG. 5 is an explanatory view of a state where the insertion piece of the flexible circuit board according to the present invention is inserted into a connector and fixed.

FIG. 6 is a partial plan view of a conventional flexible circuit board.

FIG. 7 is an enlarged sectional view taken along line VII-VII in FIG.

FIG. 8 is an explanatory view showing a state in which an insertion piece of a conventional flexible circuit board is inserted into a connector and fixed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS A Flexible circuit board 1 Circuit pattern 4 Circuit board main body 5 Reinforcement plate 6 Electrode pattern 7 Insertion piece 9 Connector 10 Functional piece 11 Transverse part 12 Communication part 51 Edge of reinforcing board X Direction away from end of circuit board main body

Claims (1)

(57) [Claims] 1. A circuit board body having a plurality of circuit patterns covered with an electrically insulating thin film, and an electrode formed by exposing ends of the plurality of circuit patterns to a surface of an end of the circuit board body. A pattern and a reinforcing plate joined to the back surface of the end of the circuit board body in an overlapping manner.
Then, the end of the circuit board body is inserted into the connector.
In a flexible circuit board formed as a fixed insertion piece , the flexible circuit board is connected to a movable portion and the movable
The flexible circuit board is reinforced as the part moves.
Deformation occurs in the adjacent area adjacent to the joint area of the plate
The reinforcing plate is joined to the back surface of the circuit board main body over the exposed portion of the electrode pattern and the adjacent portion thereof, and the circuit board is formed in the adjacent region starting from the edge of the reinforcing plate. A functional piece is integrally provided on the reinforcing plate so as to extend in a direction away from an end of the main body, and a plurality of transverse sections extending in a direction crossing the circuit board main body and the functional piece are connected to the transverse section. And a connecting portion extending along the longitudinal direction of the circuit board main body, formed in a meandering shape by the traversing portion and the connecting portion, and a mutual interval between each adjacent traversing portion is set to be greater than the reinforcing plate. A flexible circuit board characterized by gradually decreasing in a direction away from the flexible circuit board.