JP2857265B2 - Click action switch unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin click action switch unit having improved click feeling.

[0002]

2. Description of the Related Art Flexible printed wiring boards (FPC)
The switch unit using the click spring and the click spring has high reliability, and has excellent features capable of achieving a reduction in thickness, space, and cost. For this reason, this type of switch unit is widely used for operation keys of electric equipment and the like. In particular, a switch unit using this FPC is frequently used as a switch unit having a small size and many key input parts that cannot be realized by a membrane switch using a PET printed circuit board, and also requires heat resistance that cannot be realized by PET. It is also applied to applications.

FIG. 4 is a perspective plan view showing the arrangement of components of a conventional switch unit using an FPC and a click spring, and FIG. 5 is a sectional view taken along line 5-5 in FIG. The upper surface circuit conductor 2 of the flexible printed wiring is provided on the surface of the base film 6, and the insulating film 3 is laminated on the printed wiring circuit conductor 2. 1
Opposite portions of the pair of printed wiring circuit conductors 2 are formed in a comb-teeth shape, and this comb-teeth portion serves as an electrode circuit 5. The comb-shaped electrode circuit 5 is arranged so that each tooth portion is alternately located.

An insulating film 3 is laminated on the printed wiring circuit conductor 2. The insulating film 3 is provided with an opening 4 in which a position matching the electrode circuit 5 is hollowed out in a circular shape. Then, on this insulating film 3, a click spring 1 made of a dome-shaped conductive metal having a strong spring property puts its edge on a portion around the opening 4 of the insulating film 3,
The center of the top is aligned with the center of the opening 4 and arranged. On the back surface of the base film 6, a lower surface circuit conductor 7 of the printed wiring and an insulating film 8 are laminated. The entire switch unit is adhesively fixed to an external housing of the device, and the unit is used in an environment where it is not deformed.

In the click action switching unit configured as described above, when the click spring 1 is pressed, the center portion is displaced and deformed, as shown in FIG. Contact.
As a result, the electrode circuit 5 is short-circuited and the pair of flexible printed circuit conductors 2 are electrically connected to each other. In this case, since the deformation of the click spring 1 is such that the top of the dome is dented, a click feeling is obtained by this deformation.

[0006]

FIG. 6 is a schematic diagram showing the deformation behavior of the click spring 1. As shown in FIG. Reference numeral 9 denotes an outer surface of the spring 1 in a stationary state, and reference numeral 12 denotes a bottom surface of the spring 1 or a surface of the insulating film 3 in a stationary state. Symbols 10 and 1
Reference numeral 1 denotes the surface of the spring 1 when deformed. FIG. 7 is a load displacement curve of the click spring during deformation. In FIG. 6, when the spring 1 is deformed from the stationary state, the deformed state of the spring 1 after the click action is completed is, as indicated by reference numeral 11, the center of the spring 1 is lower than the spring bottom 12 in the stationary state. Become. That is, the deformation of the spring 1 is in an equilibrium state in a state where the central portion of the spring 1 is below the spring bottom surface 12 and a portion of the spring 1 having a radius of approximately 2/3 is raised above the spring bottom surface 12. The click action is completed only after deforming to the state indicated by reference numeral 11. Therefore, what is shown by C in FIG. 6 is the original click action process of the click spring, and the curve shown by reference numeral 14 in FIG. 7 is a load displacement curve, and the one shown by reference numeral Sc is the load change curve at that time. Become.

However, in the conventional click action switching unit, when the spring 1 is pressed, the spring 1 comes into contact with the electrode circuit 5 as shown by reference numeral 10 in FIG. Deformation stops at the spring bottom surface or the electrode circuit surface. Therefore, the amount of displacement of the spring 1 becomes A in FIG. Accordingly, the load displacement curve when the spring 1 is pressed is indicated by reference numeral 13 in FIG. As described above, when the spring 1 is deformed by the key operation and the spring 1 and the electrode circuit 5 come into contact with each other and are turned on, the downward displacement of the spring 1 ends. For this reason, the conventional switching unit has a drawback that it is not possible to obtain a click feeling at the time of designing a click spring as indicated by reference numeral 14 in FIG.

In order to improve the click feeling, there is a method of increasing the displacement by strengthening the narrowing of clicks.
Then, the thickness of the click spring increases, which hinders a reduction in the thickness of the unit. In addition, the maximum load of the click spring is greatly increased, and the durability is deteriorated. This problem is a fatal drawback when downsizing the switch structure.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a click action switch unit capable of obtaining a click feeling inherent in a click spring and obtaining a good click feeling. And

[0010]

A click action switching unit according to the present invention comprises: a base film;
A flexible printed circuit conductor provided with a comb-shaped electrode circuit provided on the surface of the base film; an insulating film provided on the printed circuit circuit conductor and provided with a window exposing the electrode circuit; A click spring whose peripheral edge is located on the insulating film and which is laminated on the back surface of the base film and whose diameter is smaller than the diameter of the peripheral edge of the click spring and which is closer to the window of the insulating film.
And a back layer provided with a large-diameter opening.

[0011]

According to the present invention, an opening having a diameter smaller than the diameter of the peripheral edge of the click spring is provided on the back surface layer laminated on the back surface of the base film. After contacting the circuit, it can be further deformed into the opening. For this reason,
As shown by reference numeral 11 in FIG. 6, since the click spring can be deformed until the click action is completed, an extremely good click feeling can be obtained. In addition, as a back surface layer, there is a laminate of a printed wiring circuit conductor and an insulating film.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a plan projection view showing an arrangement of members of a click action switch unit according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line 2-2 of FIG. On the surface of the base film 6, a pair of upper surface circuit conductors 2 of a flexible printed wiring is formed. The printed wiring circuit conductor 2 includes a comb-shaped electrode circuit 5, and the two electrode circuits 5 are arranged with the comb-teeth portions alternately located.
An insulating film 3 is laminated on the printed circuit conductor 2 as a coverlay film. The insulating film 3 has a portion corresponding to the electrode circuit 5 cut out in a circular shape, and an opening 4 is provided in this portion.
Then, a dome-shaped click spring 1 made of a conductive metal having a strong spring property is disposed on the insulating film 3 with its peripheral edge aligned with the center of the top of the opening 4.

On the other hand, a lower surface circuit conductor 7 of the printed wiring is formed on the back surface of the base film 6, and an insulating film 8 is further laminated on the lower surface circuit conductor 7. The lower circuit conductor 7 is provided with a cutout pattern 15 having a hollow shape concentric with the opening 4 of the insulating film 3.
Similarly, a circular opening 16 is formed in the insulating film 8. The opening 4, the cut pattern 14, and the opening 1
5 are concentrically hollowed out, the diameter of which is the smallest at the opening 4 of the insulating film 3, then the opening 15 of the insulating film 8 on the back surface, and the punching pattern 14 of the lower surface circuit conductor 7 in that order. It is getting bigger. However, the diameter of the punching pattern 14 having the largest size is also the click spring 1
Is smaller than the diameter of the peripheral portion of Note that the diameter of the opening 4 of the insulating film 3 on the front side needs to be large enough to prevent contact with the power supply circuit 5 due to inversion of the click spring 1. The insulating films 3 and 8 are provided to insulate the flexible printed wiring upper surface circuit conductor 2 and the lower surface circuit conductor 7 and to protect the circuit.

In the click action switch unit configured as described above, when the click spring 1 is pressed at the time of key input, the center of the spring 1 is depressed downward as shown in FIG. The part deforms so as to bulge upward. In the course of the deformation of the spring 1, first, the spring 1 comes into contact with the electrode circuit 5. And
Since the cutout pattern 15 and the opening 16 are provided in the circuit conductor 7 and the insulating film 8 on the back surface of the base film 2, respectively, the spring 1 is further deformed together with the circuit conductor 2 and the base film 6, and fixes this switch unit. Surface of member 1
The spring 1 can be deformed until the base film 6 comes into contact with 8. This state corresponds to the deformed state indicated by reference numeral 11 in FIG. 6, and is a state in which the click action has been completed. Accordingly, in the process of deforming the spring 1, the spring 1
The finger which is displaced by the load displacement curve indicated by reference numeral 14 and presses the click spring 1 receives a reaction force of this load. For this reason, the finger receives a sufficient click feeling under the load fluctuation indicated by S _C (= S _A + S _B ) in FIG. Spring 1 by finger
When the pressing is stopped, the shape of the click spring 1 is restored to the original dome shape, and the shape of the base film 6 is restored to the original flat plate shape by the appropriate elasticity.

In this embodiment, as shown by reference numeral 11 in FIGS. 3 and 6, the click spring 1 has a center portion at the bottom surface of the spring 1, that is, an insulating film 3 on which the peripheral portion of the spring 1 is placed.
Is displaced downward beyond the position of the surface of the base film 6.
The spring 1 is deformed until it contacts the surface 18 of the fixing member. Therefore, when the spring 1 stops deforming, the click action has been completed, and the displacement amount inherent to the click spring is obtained, so that the finger can obtain a sufficiently good click feeling in the process of the deformation. .

In this embodiment, since the circuit conductor 2 of the flexible printed wiring is deformed, the electrode circuit 5
It is conceivable that bending fatigue rupture occurs. However, in the present embodiment, the deformed portion is the edge of the opening 15 of the back surface insulating film 8, and the opening 4 of the upper surface insulating film 3 is smaller in diameter than the opening 16 of the back surface insulating film 8. In this deformed portion, the circuit conductor 2 is sandwiched between the insulating film 3 and the base film 6. Therefore, the electrode circuit conductor 2 is supported and reinforced by the insulating film 3 and the base film 6. This prevents bending fatigue fracture of the electrode circuit 5 and the circuit conductor 2 due to the deformation of the base film 6.

The above-mentioned click spring 1 has, for example, a peripheral edge diameter of 6.0 mm, an overall displacement amount of C = 0.25 mm, and a penetration amount of B = 0.05 mm. Further, as an example, the base film 6 has a thickness of 0.025 mm, a rolled copper foil conductor (circuit conductors 2 and 7) has a thickness of 0.018 mm, and an insulating film has a thickness of 0.4 mm. However, the thickness of each layer is set based on the amount of displacement or load displacement characteristics of the click spring 1 to be used.

[0019]

According to the present invention, since the opening is provided in the back surface layer on the back surface of the base film, the amount of deformation of the click spring 1 increases, and the click spring 1 can be deformed until the click action is completed. Therefore, the original load displacement of the click spring can be realized substantially as it is, and a good click feeling can be obtained.

Further, the contact time between the electrode circuit portion of the flexible printed wiring and the click spring can be lengthened. As a result, contact malfunction due to chattering can be easily avoided by delay recognition.

Further, the click feeling can be improved without increasing the layer thickness of the unit such as the click spring 1. Further, the manufacturing process is the same as that of the conventional case, and therefore, it is possible to improve the feel of the click feeling without increasing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a perspective plan view showing a click action switch unit according to an embodiment of the present invention.

FIG. 2 is a sectional view along line 2-2 of FIG.

FIG. 3 is a diagram showing the operation of the present embodiment.

FIG. 4 is a perspective plan view showing a conventional click spring.

FIG. 5 is a cross-sectional perspective view of the same taken along line 5-5.

FIG. 6 is a plan view showing a conventional click action switch unit.

FIG. 7 is a schematic diagram showing a load displacement curve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Click spring 2; Upper surface circuit conductor 3, 8; Insulating film 4, 16; Opening 5; Electrode circuit 6; Base film 7; Lower surface circuit conductor

Claims (1)

(57) [Claims] 1. A base film, a flexible printed circuit conductor provided on a surface of the base film and having a comb-shaped electrode circuit, and a window laminated on the printed circuit conductor to expose the electrode circuit. And a click spring made of a dome-shaped conductive metal and having a peripheral edge located on the insulating film, and a diameter smaller than the diameter of the peripheral edge of the click spring laminated on the back surface of the base film. And a back layer having an opening having a diameter larger than that of the window of the insulating film .