Patent Grant
6924448
The present invention relates to a movable contact unit with operating projections that is used, for example, in operating panels of a variety of electronic apparatuses, and also relates to a method of mounting the operating projections, and an operating panel switch using the movable contact unit with the operating projections.
Recently, as portable electronic apparatuses have increased in number, a variety of electronic apparatuses have become compact and lightweight. An operating panel switch for the electronic apparatus is low-profile and affords a good click feel and an electrically stable contact, so that a so-called movable contact unit, the insulating resin film of which holds a plurality of separate domed movable contacts formed out of an electrically conductive and resilient metal plate, has found wide use.
To improve operability, the operating panel switch is demanded of an arrangement of keys corresponding to respective switches intended to afford different click feels.
Referring to
A plurality of projecting members 5A is each fixed to base film 1 by adhesive resin 5B. These projecting members 5A are formed by stamping a film of resin into cylindrical shapes and hence are circular when viewed from above. Projection member 5A and adhesive resin 5B form operating projection 5.
When the movable contact unit with the operating projections is mounted to the apparatus, separator 4 is removed, and base film 1 is bonded to wiring board 7 by adhesive layer 2. Respective central portions of movable contacts 3 each face corresponding central fixed contact 6A across a given clearance, while respective lower borders of movable contacts 3 are each placed on corresponding outer fixed contact 6B. Movable contact 3 and corresponding fixed contact 6 form one switch. Above each operating projection 5, operating button 8 of the apparatus is disposed.
Referring to
When pressed, operating button 8 moves downward, and downward pushing force is applied accordingly to an upper end of cylindrical projecting member 5A contacting bottom surface 8A of operating button 8. In other words, the pushing force is applied to the central portion of movable contact 3 via projecting member 5A and base film 1. When this pushing force becomes greater than shape retaining force of movable contact 3, domed movable contact 3 is turned inside out while providing the click feel, whereby a bottom surface of its central portion contacts central fixed contact 6A. As a result, central fixed contact 6A and outer fixed contact 6B of wiring board 7 are electrically coupled to each other via movable contact 3.
When released from the pushing force, movable contact 3 restores its original shape with its own resilient restoring force, so that the bottom surface of its central portion departs from central fixed contact 6A. This means that central fixed contact 6A and outer fixed contact 6B of wiring board 7 return to a state in which these contacts 6A, 6B are electrically isolated from each other.
To set operating force (corresponding to the above-mentioned pushing force), which acts on a specified movable contact of the plurality of movable contacts 3, different from operating force which acts on another movable contact of the above-constructed conventional movable contact unit, the following methods are generally conceivable.
The specified movable contact is set different from other movable contacts in diameter, thickness or material.
The operating projection corresponding to the specified movable contact is set different from other operating projections in shape or material.
The above-mentioned examples, however, increase the variety of elements to be used and complicate a manufacturing process, thus increasing costs.
The present invention addresses the conventional problems discussed above and aims to provide a movable contact unit with operating projections that facilitates setting of desired operating force which acts on a specified movable contact without increasing the variety of elements to be used and also aims to provide a method of mounting the operating projections and an operating panel switch using the movable contact unit with the operating projections.
The movable contact unit with the operating projections of this invention includes:
a plurality of domed movable contacts opening downward, the movable contacts formed out of electrically conductive and resilient sheet metal;
a base film holding the movable contacts in place at a bottom surface thereof; and
a plurality of projecting members fixed to a top surface of the base film by an adhesive to correspond to the respective movable contacts, each of the projecting members facing a central portion of the corresponding movable contact across the base film,
wherein the amount of adhesive fixing a specified projecting member of the plurality of projecting members to the base film differs from the amount of adhesive fixing another projecting member.
The method of mounting the operating projections according to this invention includes the steps of:
(a) forming an adhesive into a first adhesive layer having a uniform thickness;
(b) preparing an in-process workpiece including a specified arrangement of a plurality of movable contacts held to a bottom surface of a base film by a second adhesive layer;
(c) causing the adhesives to adhere to respective leading end parts of a plurality of transfer pins, arranged to correspond to the specified arrangement of the movable contacts, by:
(d) transferring the adhesives, which have adhered to the respective leading end parts of the transfer pins in the step (c), to a top surface of the base film with each of the adhesives corresponding to a central portion of the corresponding movable contact;
(e) placing projecting members on the respective adhesives transferred; and
(f) curing the adhesives,
wherein a specified transfer pin of the plurality of transfer pins differs from another transfer pin in one of shape and size so that the amount of adhesive adhering to the specified transfer pin differs from the amount of adhesive adhering to another transfer pin.
The operating panel switch of this invention includes:
a plurality of domed movable contacts opening downward, the movable contacts formed out of electrically conductive and resilient sheet metal;
a base film formed with an adhesive layer at a bottom surface thereof, the base film holding the movable contacts in place by means of the adhesive layer;
a plurality of projecting members fixed to a top surface of the base film by an adhesive to correspond to the respective movable contacts, each of the projecting members facing a central portion of the corresponding movable contact across the base film; and
a wiring board including a plurality of fixed contacts arranged to face the movable contacts, respectively,
wherein the amount of adhesive fixing a specified projecting member of the plurality of projecting members to the base film differs from the amount of adhesive fixing another projecting member, and the base film is bonded to the wiring board by the adhesive layer.
An exemplary embodiment of the present invention is demonstrated hereinafter with reference to
Parts of base film 10 that correspond to respective movable contacts 12 (12A, 12B) are each formed into a shape matching the domed shape of movable contact 12.
Projecting members 14A, 15A are fixed to a top surface of base film 10 by respective adhesive resins 14B, 15B to correspond to respective central portions of movable contacts 12 (12A, 12B). Projecting member 14A and adhesive resin 14B form operating projection 14, while projecting member 15A and adhesive resin 15B form operating projection 15. Projecting members 14A, 15A are formed by stamping an elastic film of resin having uniform quality and a uniform thickness into cylindrical shapes of the same diameter. Cylindrical projecting member 14A has one circular end face and a curved side fixed to base film 10 by adhesive resin 14B, and similarly, cylindrical projecting member 15A has one circular end face and a curved side fixed to base film 10 by adhesive resin 15B.
With projecting members 14A, 15A fixed, the area (or the amount) of adhesive resin 14B differs from the area (the amount) of adhesive resin 15B on base film 10. In other words, adhesive resin 14B is formed to have fixed diameter D14 differing from fixed diameter D15 of adhesive resin 15B.
It is to be noted that, for example, the material for projecting members 14A, 15A and material for adhesive resins 14B, 15B are not limited. However, in cases where an ultraviolet curing adhesive is used for adhesive resins 14B, 15B, as will be described later, projecting members 14A, 15B preferably use a film of resin which passes not less than 70% of all light including ultraviolet light for curing the adhesive.
In the present embodiment, movable contacts 12A, 12B are made of the same material and have the same shape, and projecting members 14A, 15A are made of the same material and have the same shape
As shown in
When operating button 22 is pressed, pushing force is exerted accordingly on movable contact 12A (12B) via operating projection 14 (15) as shown in FIG. 3. When this pushing force becomes greater than shape retaining force of movable contact 12A (12B), movable contact 12A (12B) is turned inside out, whereby a bottom surface of the central portion of movable contact 12A (12B) contacts central fixed contact 20A. Consequently, electrical conduction is established between central fixed contact 20A and outer fixed contact 20B via movable contact 12A (12B).
As described above, the movable contact unit with the operating projections of the present embodiment uses movable contacts 12A, 12B of the same type and projecting members 14A, 15A of the same type, while adhesive resins 14B, 15B differ from each other in fixed diameter. In other words, as shown in
Although movable contacts 12A, 12B of the same type and projecting members 14A, 15A of the same type are used, adhesive resins 14B, 15B can thus cause different operating forces or click feels. In other words, with the variety of elements to be used not increased, the desired click feel can be set for the specified movable contact simply by changing the area of the cured adhesive through adjustment of the amount of adhesive to be applied.
Since the pushing force is applied to the central portion of movable contact 12A or 12B via projecting member 14A or 15A by pressing operating button 22, there are few cases where the click is felt less even when, for example, operating button 22 is placed off-center.
When operating button 22 is released from the pushing force, movable contact 12A (12B) expands upward with its own resilient restoring force and restores its original shape. As a result, the bottom surface of the central portion of movable contact 12A (12B) departs from central fixed contact 20A, whereby central fixed contact 20A and outer fixed contact 20B return to a state in which these contacts 20A, 20B are electrically isolated from each other.
As described above, the movable contact unit with the operating projections of the present embodiment is constructed to have the plurality of movable contacts 12 held to one base film 10, and the operating forces acting on the respective movable contacts during pressing are set in accordance with the respective areas of adhesive resins 14B, 15B bonding the respective projecting members 14A, 15A to base film 10. Since the desired operating force can thus be set for the specified movable contact, an arrangement of keys (or switches) that has favorable operability can be realized easily at low cost without an increase in the number of elements to be used.
In the present embodiment, cylindrical projecting members 14A, 15A have their respective circular end faces and curved sides fixed to base film 10 by respective adhesive resins 14B, 15B. However, those curved sides may not be bonded.
Referring to
First, a process of preparing an adhesive layer (first adhesive layer) is carried out. In this process, the specified amount of ultraviolet curing adhesive resin 30 is placed on stage 31 as shown in FIG. 4A. Adhesive resin 30 is in the form of yet-to-be-cured paste. Top surface 32 of stage 31 is a smooth plane larger than the movable contact unit to be manufactured, and spacers 33 of the same thickness on both sides of top surface 32.
While abutting against spacers 33 of stage 31, squeegee 34 is moved as shown in
Next, a process of preparing transfer is carried out. In this process, a plurality of transfer pins 40 made of metal is lowered from above into adhesive resin layer 35 as shown in
The arrangement of transfer pins 40 matches the arrangement of the respective central portions of movable contacts 12 of the movable contact unit to be manufactured. Transfer pins 40 hold some adhesive resin 30 of adhesive resin layer 35 simultaneously.
It is to be noted here that the bottom surface of the leading end part of the transfer pin corresponding to projecting member 15A is larger in area than that of another transfer pin for increased operating force.
Concurrently with the process of preparing the adhesive layer, a process of preparing in-process workpiece 50 is carried out. In-process workpiece 50 made in this process (not shown) includes movable contacts 12 whose top surfaces are held by adhesive layer 11 formed on the bottom surface of base film 10, and separator 13 bonded by adhesive layer 11. Since all those movable contacts 12 used are of the same type, movable contacts 12 are successively bonded to base film 10, so that productivity increases.
Next, a transferring and curing process is carried out. In this process, transfer pins 40 each having the specified amount of adhesive resin 30 are pressed against the top surface of base film 10 of in-process workpiece 50 at the same time as shown in
Subsequently, as shown in
Finally, adhesive resins 30 are cured simultaneously with the ultraviolet light applied above projecting members 14A, 15A. Here, projecting members 14A, 15A transmit the ultraviolet light, so that adhesive resins 30 cure without fail.
Instead of being applied from above, the ultraviolet light may be applied from any other direction, depending on how equipment is installed.
The equipment required here may be simplified. No defective including deformation is produced because base film 10 is unaffected by heat or the like.
As is clear from the above description, the arbitrary adjustment can be made to the operating force which acts on each movable contact by changing the diameter of each transfer pin 40.
In the above-described embodiment, the amount of adhesive to be transferred has been adjusted by changing the diameter of the transfer pin. However, the amount of adhesive to be transferred can be adjusted by changing the length of the transfer pin. For example, the transfer pin corresponding to projecting member 15A is made longer than other transfer pins. In this case, this transfer pin corresponding to projecting member 15A goes down more deeply into the adhesive resin layer than other transfer pins in the process of preparing transfer. In other words, the leading end part of the transfer pin corresponding to projecting member 15A holds more adhesive resin. As a result, advantages similar to those obtained when the diameter is increased can be obtained. In the embodiment, the transfer pins are cylindrical but may have any other shapes.
With the shapes of transfer pins 40 unchanged, a slight adjustment to the operating forces can be made by changing the amount of adhesive resin held by each transfer pin 40 through change of the distance covered by transfer pins 40 when these pins 40 are lowered in the transferring and curing process.
In the embodiment, adhesive resins 30 are transferred to base film 10 holding movable contacts 12. However, these adhesive resins 30 may be transferred to flat base film 10 before movable contacts 12 are held by base film 10. This stabilizes the amount of adhesive resin 30 in transfer or application. In this case, after transfer, the base film is machined into a shape for holding the movable contacts, and movable contacts 12 are thereafter held by the base film.
Similar advantages can be obtained if projecting members 14A, 15A are light-transmitting or semitransparent. The use of especially polyethylene terephthalate (PET), which transmits not less than 85% of all light, allows adhesive resins 30 to cure more favorably. PET is inexpensive and lends itself to stamping, thus increasing the productivity in manufacture of the movable contact unit with the operating projections.
It is preferable that pressure applied for transferring adhesive resin 30 to transfer pin 40, pressure applied for transferring adhesive resin 30 to base film 10, and the pressure applied for holding projecting members 14A, 15A to respective adhesive resins 30 each range from 0.5 to 3 N for each transfer pin 40. With an applied pressure less than 0.5 N, adhesive resin 30 is inadequately transferred, and with an applied pressure more than 3 N, adhesive resin 30 spreads more than necessary. If the applied pressure is within the above range, there are few cases where projecting members 14A, 15A lean, and the heights and positions of projecting members 14A, 15A stabilize.
It is to be noted that instead of the pressurization and transfer system using transfer pins 40, a device such as a dispenser may be employed for applying adhesive resin 30. In this case, the amount of adhesive resin to be applied may be controlled by changing discharge time or discharge pressure.
In-process workpiece 50 may be integrally formed, and the base film or separator may be in the form of a hoop. With the base film or separator in hoop form, the productivity increases, and the movable contact unit with the operating projections can be manufactured at lower cost with ease.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-352395 | Dec 2002 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5924555 | Sadamori et al. | Jul 1999 | A |
| 6369801 | Boireau et al. | Apr 2002 | B2 |
| 6388518 | Miyatani | May 2002 | B1 |
| 6492602 | Asai et al. | Dec 2002 | B2 |
| 6743994 | Adachi | Jun 2004 | B2 |
| Number | Date | Country |
|---|---|---|
| 2002-216582 | Aug 2002 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20040154912 A1 | Aug 2004 | US |
