JPH07211184A - Switch utilizing flexible printed wiring board - Google Patents

Abstract

PURPOSE:To obtain a switch for utilizing a flexible printed wiring board on which a good contact status can be obtained even if a foreign object is interposed between a movable contact point and a fixed contact point. CONSTITUTION:A switch 1 is designed to use a push button 3 and a base member 2 for such a switch of the conventional embodiment. In the base member 2, are formed the center of a fixed contact point 51 on a surface 2a side for supporting a fixed contact point support 5, and a circular shaped hole 21 whose center coincides corth the above fixed contact point 51 and having a base part. However, the diameter of the hole 21 is smaller than diameters of a movable contact point 41 and of the fixed contact point 51. In the push button 3, its pressing part 31 is formed in a cylindrical shape having a diameter greater than that of the hole 21 which the base member 2 has, and an end part 31a for pressing its movable contact point support 4 is formed in a spherical shape expanding to a movable contact point support 4 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch in which a conductive layer of a flexible printed wiring board is used as a contact, and relates to a structure improved so as to reduce the incidence of contact failure caused by dust or the like.

[0002]

2. Description of the Related Art A switch using a conductive layer of a flexible printed wiring board as a contact is used in various electric devices. FIG. 3 is a side cross-sectional view of the main part showing a state of a switch using such a conventional flexible printed wiring board when opened, and FIG. 4 shows a closed state of the switch shown in FIG. It is a side sectional view of the main part shown. In FIGS. 3 and 4, reference numeral 9 denotes a flexible printed wiring including a movable contact support 4, a fixed contact support 5, a spacer 6 as a holding member, an upper member 7, a base member 81, and a push button 82 as a pressing member. It is a switch that uses a board. The movable contact support 4 is, for example, a thin sheet made of polyimide resin [for example, a sheet having a thickness of 0.25 (mm). ) Is used as a base, and a flexible printed wiring board on which a conductive layer is formed by adhering a copper foil on one side is used as a material, and the conductive layer has a conductive property such as an etching treatment. A circular movable contact 41 is formed in the main part of the layer by a processing method that is usually performed on the layer.

The fixed contact support 5 is made of a flexible printed wiring board similar to that used in the movable contact support 4, and this conductive layer is formed in the same manner as in the case of the movable contact support 4. A circular fixed contact 51 having a diameter equal to that of the movable contact 41 is formed in a main portion. The fixed contact support body 5 is held by a base member 81 made of, for example, a synthetic resin material on the side opposite to the fixed contact 5a. In the movable contact support 4, the movable contact 41 and the fixed contact 51 are opposed to each other by inserting a spacer 6 made of synthetic resin, for example, on the side of the fixed contact support 5 where the fixed contact 51 is formed. A gap (G) is formed between the surfaces so that the movable contact 41
Are held facing the fixed contact 51. The lead wires from the movable contact 41 and the fixed contact 51 are integrally formed with the movable contact 41 and the fixed contact 51 from a conductive layer included in the flexible printed wiring board forming the movable contact support 4 and the fixed contact support 5. It is possible to

The upper member 7 is made of, for example, a synthetic resin material, is provided so as to cover the movable contact support 4 above the side opposite to the movable contact 4a, and a portion directly above the movable contact 41 has, for example, a circular shape. Through hole 7a is provided. The upper member 7 may be a switch 9 or a member for a cover of an electric device including the switch 9. The push button 82 is made of, for example, a synthetic resin material,
A columnar button portion 8 having a diameter smaller than the diameter of the through hole 7a.
22 and a columnar intermediate portion 823 formed on one end side of the button portion 822 and having a diameter larger than the diameter of the through hole 7a.
And an end portion which is formed concentrically with the button portion 822 and on the side opposite to the button portion of the intermediate portion 823, and has a diameter smaller than the diameter of the movable contact 41 and a plane perpendicular to the central axis of the push button 82. And a columnar pressing portion 821 having 821a. The push button 82 has a button portion 8
22 is inserted into the through hole 7 a of the upper member 7, and is interposed between the upper member 7 and the movable contact support 4. The push button 82 is also not shown so that a slight gap is always formed between the end 821a of the pressing portion 821 on the side opposite to the intermediate portion and the side 4a of the movable contact support 4 opposite to the movable contact. The spring body presses and holds the upper member 7 side.

Since the conventional switch using the flexible printed wiring board is constructed as described above, the movable contact 41 and the fixed contact 51 are always electrically separated from each other, and the switch is in an off state. Has become. In the switch 9 in the off state, when the push button 82 is pressed against the pressing force of the spring body by pressing the end portion 822a of the button portion 822 on the side opposite to the intermediate portion, the pressing portion 821 of the push button 82 is pressed. The end portion 821a presses the movable contact support body 4 at its counter movable contact side 4a. The movable contact support 4 made of a flexible printed wiring board pressed by the end portion 821a of the push button 82 is deformed toward the fixed contact support 5 because its base has elasticity. When the push button 82 is further pressed and the movable contact support 4 is deformed by the length of the gap (G), the push button 82 is pressed.
Since the end portion 821a of the switch is a plane perpendicular to the central axis of the push button 82, the movable contact point 41 and the fixed contact point 51 are in contact with each other over substantially the entire surfaces thereof facing each other, and the switch 9 has a small contact resistance. The state is closed. By further pressing the push button 82 from this state, a desired contact pressure is applied between the movable contact 41 and the fixed contact 51, and the switch 9 is held in the closed state, that is, the ON state.

In the switch 9 in the ON state described above,
When the push button 82 is released, the push button 82
Is returned to its original position by the spring body. Further, the movable contact support body 4 returns to the off-state position due to the elasticity of the base thereof, and a gap (G) is formed between the surfaces of the movable contact 41 and the fixed contact 51 facing each other. As a result, the movable contact 41 and the fixed contact 51 are electrically separated from each other, so that the switch 9 returns to the OFF state again.

The pressing body is not limited to the push button 82 described above, and it is needless to say that it is possible to adopt various operating structures like general switches.

[0008]

A switch 9 using the above-mentioned conventional flexible printed wiring board.
Has a feature that the switch can be configured with a relatively small number of parts by using a flexible printed wiring board as the contact and its supporting member. However, the switch 9 will be described below. There is a problem. That is, the opposing surfaces of the movable contact 41 and the fixed contact 51 are planes parallel to each other, and the movable contact 41 is pressed toward the fixed contact 51 by the push button 82 while maintaining the parallel plane. .
Therefore, for some reason, the movable contact 41 and the fixed contact 5
When foreign matter such as dust enters between the planes where 1 faces each other,
The contact between the movable contact 41 and the fixed contact 51 may be obstructed, resulting in a poor contact state, making it impossible to perform a reliable switch operation.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to obtain a good contact state even if foreign matter is present between the movable contact and the fixed contact. It is to provide a switch using a possible flexible printed wiring board.

[0010]

Means for Solving the Problems The above-mentioned objects of the present invention are: 1) a thin plate-like movable contact support made of a flexible printed wiring board formed so that a conductive layer can be used as a movable contact; A thin plate-shaped fixed contact support made of a flexible printed wiring board formed so that the conductive layer on the surface side facing the fixed contact can be used as a fixed contact, a base member that holds the fixed contact support on the non-fixed contact side, and a movable A holder for holding the movable contact support so that a gap is always formed between the contact and the fixed contact, and the movable contact when the movable contact and the fixed contact are closed. In a switch using a flexible printed wiring board having a pressing body that presses the contact support from the side opposite to the movable contact formation side, the base member is a fixed contact on the surface side that holds the fixed contact support. A circular recess or hole having an area smaller than the area of the movable contact and the fixed contact is provided at a corresponding position, and the portion of the pressing body that presses the movable contact support is larger than the diameter of the recess or hole of the base member. A cylindrical shape having a large diameter is formed, and an end portion that presses the movable contact support body has a curved surface shape that swells toward the movable contact support body, or 2) in the means described in 1 above, The movable contact support has a circular movable contact, the fixed contact support has a circular fixed contact having substantially the same diameter as the movable contact, and presses the movable contact support of the pressing body. The end of the part that presses the movable contact support is formed by a spherical shape that bulges toward the movable contact support.

[0011]

According to the present invention, the base member is smaller than the area of the circular movable contact and the area of the circular fixed contact, for example, at the position corresponding to the fixed contact on the surface side holding the fixed contact support. The pressing member has a circular recess or hole with an area, and the portion of the pressing member that presses the movable contact support has a cylindrical shape with a diameter larger than the diameter of the recess or hole of the base member. The end that presses the body is configured to have a curved curved surface such as a spherical shape that bulges toward the movable contact support side.When the switch is turned on, the pressing body is operated to move the pressing body. First, the movable contact support body is pressed by the pressing-side end portion having a curved surface shape that swells toward the contact support body side. The movable contact support body, which is made of a flexible printed wiring board and is highly elastic, is locally deformed according to the shape of the end portion on the pressing side, and is deformed toward the fixed contact support body side as a whole. As the operation of the pressing body progresses, the movable contact support deforms beyond the length of the gap existing between the movable contact and the fixed contact and starts contact with the fixed contact support. At that time, the fixed contact support is made of a flexible printed wiring board and thus has a high elasticity, and the base member at the position where the movable contact support starts contacting the fixed contact support has a recess or a hole. Since it is present and deformation of the fixed contact support to the base member side is allowed, the deformation starts from the portion in contact with the movable contact support to the base member side. When the diameter of the deformed portion of the fixed contact support is changed to match the diameter of the recess or hole of the base member, further deformation of the fixed contact support is stopped and the pressing force applied by the pressing body is reduced. After that, it mainly contributes to the increase of the contact pressure between the movable contact and the fixed contact.

When a foreign matter is present between the movable contact and the fixed contact during the above-mentioned ON operation by the pressing body, the shape of the end portion of the pressing body on the pressing side of the foreign matter is present in the foreign matter. By forming a curved surface that swells toward the support, for example, when the curved surface is spherical, (1
Since the force (F ₁ ) according to the formula) acts, the foreign matter is excluded to the outside of the contact portion between the movable contact and the fixed contact. When the foreign matter is firmly attached to the movable contact or the fixed contact, the fixed contact support near the portion where the foreign matter is attached has a recess or hole in the base member. ,
Due to the elasticity of the fixed contact support, extraneous material is deformed inside the recess or hole by the amount of foreign matter. As a result, the movable contact and the fixed contact in the area where no foreign matter exists can contact each other.

[0013]

## EQU1 ## F ₁ = cos θ × F ………………………… (1) where F is the pressing force of the pressing body and θ is the spherical center of the part where foreign matter is present. Is an angle of the normal line from (therefore, it is a value corresponding to the distance from the central axis of the pressing body at the portion where the foreign matter exists).

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 is a side sectional view of a main part of a switch using a flexible printed wiring board according to an embodiment of the present invention when the switch is opened, and FIG.
FIG. 3 is a side sectional view of a main part of the switch shown in FIG. The same parts as those of the switch using the conventional flexible printed wiring board shown in FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted. In FIGS. 1 and 2, reference numeral 1 is different from the conventional switch 9 shown in FIGS. 3 and 4 in that the push button 3 is replaced with the push button 82 which is the pressing body, and the base member 81 is replaced. The switch uses the base member 2.

The base member 2 has a surface 2 for holding the fixed contact support 5 with respect to the base member 81 provided in the switch 9.
The difference is that the center of the fixed contact 51 and the center of the fixed contact 51 are aligned on the side a, and a hole 21 having a circular shape and a bottom is formed. However, the diameter of the hole 21 is smaller than the diameters of the movable contact 41 and the fixed contact 51. Further, the push button 3 has a columnar shape in which the pressing portion 31 has a diameter larger than the diameter of the hole 21 of the base member 2 with respect to the push button 82 included in the switch 9, and supports the movable contact thereof. The difference is that the end 31a that presses the body 4 has a spherical shape that bulges toward the movable contact support 4 side.

Since the embodiment shown in FIGS. 1 and 2 has the above-mentioned configuration, the switch 1 is turned on by pressing the push button 3, just like the switch 9 of the conventional example. When the switch 1 is turned on, the spherical end 31a of the push button 3 which bulges toward the movable contact support 4 is
First, the movable contact support 4 is pressed to locally deform the movable contact support 4 in accordance with the shape of the end portion 31a, while deforming the movable contact support 4 toward the fixed contact support 5 as a whole. When the movable contact support 4 is deformed beyond the length of the gap (G) existing between the movable contact 41 and the fixed contact 51, the fixed contact support 5 is moved from the portion contacting with the movable contact support 4. Deformation starts inside the hole 21 of the base member 2. When the diameter of the deformed portion of the fixed contact support 5 is changed to match the diameter of the hole 21, further deformation of the fixed contact support 5 is stopped and the pressing force applied by the push button 3 is After that, mainly the movable contact 41 and the fixed contact 51
It will contribute to the increase of the contact pressure between and.

When a foreign substance is present between the movable contact 41 and the fixed contact 51 when the push button 3 is turned on as described above, the foreign substance is present between the movable contact 41 and the fixed contact 51. Since the shape of ( ₁ ) is a spherical shape that bulges toward the movable contact support body 4, the force (F ₁ ) according to (1) described above acts, and therefore foreign matter contacts the movable contact 41 and the fixed contact 51. Excluded outside the department. Further, when the foreign matter is firmly attached to the movable contact 41 or the fixed contact 51, the fixed contact support 5 near the portion where the foreign matter is attached has an extra inside of the hole 21 by the amount of the foreign matter. Deforms to the side. As a result, the movable contact 41 and the fixed contact 51 in the area where no foreign matter exists can contact each other. Whether the foreign matter is removed outside the contact portion between the movable contact 41 and the fixed contact 51 or adheres strongly to the movable contact 41 or the fixed contact 51, the movable contact 4
1 and the fixed contact 51 can contact each other over a wide area. Therefore, the movable contact 41 and the fixed contact 51
Therefore, it is possible to keep the contact resistance between and with a small value at all times.

It is to be noted that the switch 1 is turned off when the push button 3 is released from the switch 1 as in the case of the conventional switch 9. In the above description of the embodiments, the pressing-side end 31a of the push button 3 has a spherical shape that bulges toward the movable contact support 4 side, but the present invention is not limited to this. It goes without saying that a curved surface shape other than the spherical shape may be used as long as the curved surface shape bulges toward the movable contact support 4 side.

In the above description of the embodiment,
The hole 21 has a circular shape and has a bottom portion,
The present invention is not limited to this, and it may be a mere concave portion or a through hole as long as it does not hinder the deformation of the fixed contact point support body 5 when the push button 3 is pressed. Is also good.

[0020]

According to the present invention, by adopting the above-mentioned structure, even when foreign matter is present between the movable contact and the fixed contact, the movable contact and the fixed contact are in contact with each other over a wide area. Since they can be adjusted, there is an effect that a reliable switch operation can be performed.

[Brief description of drawings]

FIG. 1 is a side sectional view of a main part of a switch using a flexible printed wiring board according to an embodiment of the present invention, showing a state when the switch is opened.

FIG. 2 is a side sectional view of the main part of the switch shown in FIG. 1 showing a closed state.

FIG. 3 is a side cross-sectional view of a main portion of a conventional switch using a flexible printed wiring board when the switch is opened.

FIG. 4 is a side sectional view of a main part of the switch shown in FIG. 3 showing a closed state.

[Explanation of symbols]

 1 Switch 2 Base Member 2a Surface 21 Hole 3 Push Button 31 Pressing Part 31a End 4 Movable Contact Support 41 Movable Contact 5 Fixed Contact Support 51 Fixed Contact

Claims (2)

[Claims] 1. A thin plate-like movable contact support made of a flexible printed wiring board formed so that the conductive layer can be used as a movable contact, and the conductive layer on the side facing the movable contact can be used as a fixed contact. A thin plate-shaped fixed contact support made of a flexible printed wiring board formed in this way, a base member that holds the fixed contact support on the side opposite to the fixed contact, and a gap is always formed between the movable contact and the fixed contact. Holding body for holding the movable contact support, and a pressing body for pressing the movable contact support from the side opposite to the movable contact when attempting to close the movable contact and the fixed contact to each other. In a switch using a flexible printed wiring board equipped with, the base member is smaller than the area of the movable contact and the fixed contact at the position corresponding to the fixed contact on the surface side holding the fixed contact support. The portion of the pressing body that presses the movable contact support has a circular recess or hole with a small area, and the portion that presses the movable contact support has a cylindrical shape with a diameter larger than the diameter of the recess or hole of the base member. A switch using a flexible printed wiring board, characterized in that an end portion that presses the support body has a curved surface shape that swells toward the movable contact support body side. 2. A switch using a flexible printed wiring board according to claim 1, wherein the movable contact support has a circular movable contact, and the fixed contact support has substantially the same diameter as the movable contact. A flexible contact characterized by having a circular fixed contact, and the end of the pressing body that presses the movable contact support body at the portion that presses the movable contact support body has a spherical shape that bulges toward the movable contact support side. A switch that uses a printed wiring board.