Patent Application
20080006517
An exemplary embodiment of the present invention is demonstrated hereinafter with reference to
Adhesive 45 is the same adhesive used in the conventional unit, and the formed pattern of adhesive 45 is a critical point of the structure described in this embodiment, so that the adhesive is marked with a new reference mark “45” both in the drawings and the descriptions hereinafter.
Adhesive 45 discussed above is patterned on the underside of EL sheet 40 as shown in
Adhesive 45 is patterned on layer 35 this way: As shown in
Holding section 45A is formed smaller than the conventional one and adhesively holds the top face of movable contact 5. This structure is detailed later. Surrounding section 45B is formed extensively to the fringe of EL sheet 40.
Movable-contact unit 50 is thus constructed, and separator 7 is bonded onto the underside of unit 50 with surrounding section 45B. Separator 7 prevents movable contact 5 from being attached with dust and protects the functional layers of EL sheet 40.
Movable-contact unit 50 is removed from separator 7 before it is used, and bonded onto wired board 15 of the device with surrounding section 45B of adhesive 45, so that panel switch 60 becomes ready for use. In this status, the terminal section (not shown) of inorganic EL sheet 40 is coupled to a predetermined power feeding line (not shown).
Key mat 25 is placed over the foregoing panel switch 60 for depressing respective movable contacts 5, thereby completing an operating panel. In this operating panel, application of a given voltage to inorganic EL sheet 40 realizes surface light emission such as illuminating an extensive area, e.g. the whole surface of EL sheet 40, then key mat 25 placed over EL sheet 40 is illuminated. Since the key mat 25 is made of optically transparent material, the keytop can be highly and uniformly illuminated. Key matt 25 adaptable to the foregoing structure can limit the area to be illuminated upon necessary.
Next, the movement of the operating panel is described hereinafter, i.e. the user operates the foregoing panel switch 60 this way: Pressing the keytop of key mat 25 prompts EL sheet 40 to apply depressing force to movable contact 5, and when the depressing force exceeds a given value, the center section of movable contact 5 is reversed producing tactile feedback, so that the underside of the center section touches center fixed contact 17B placed on wired board 15. This mechanism allows outer fixed contact 17A, on which the lower end of outer rim of movable contact 5 is placed, to short with center fixed contact 17B, in other words, the switch is turned on. Then removable of the operating force restores movable contact 5 to its original position by itself; namely, the switch is turned off as shown in
To obtain adequate tactile feedback from movable-contact unit 50 even in the low temperature environment, the diameter of holding section 45A of adhesive 45 is patterned such that the area ratio of the holding section 45A vs. the plane projection area of movable contact 5 falls within 25-50%. The reason why the diameter is determined at the foregoing range is described hereinafter.
The inventors of the present invention firstly forms a movable-contact unit this way: Form holding section 45A measuring 3.6 mm in diameter, the same diameter as the conventional one, of adhesive 45 on inorganic EL sheet 40, then adhesively hold the domed movable contact 5 measuring 4 mm across and 0.2 mm high with holding section 45A, thereby forming the movable-contact unit. Expose the movable-contact unit in the environment of 0° C. for one hour. Then test the movable-contact unit whether or not it works well in the same environment. Next, expose the units in low temperature environments at −10° C. and −20° C. for one hour respectively, and then test the units whether or not they work well in the respective environments.
The test result tells that the unit exposed at 0C offers a tactile feedback similar to the one at an ordinary temperature; however, the units exposed at −10° C. and −20° C. offer almost no tactile feedback. The inventors presume that the foregoing result is caused by the following fact: Inorganic EL sheet 40 is formed of the respective functional layers laminated by printing the paste in which resin is used as binder, so that the functional layers become not flexible anymore at the low temperature environment such as at −10° C. and −20° C. Inorganic EL sheet 40 as a whole thus becomes rigid. This fact is presumed as a major cause of the poor tactile feedback. The low temperature environment also raises the viscosity of adhesive 45, which then tends to be cured. Use of holding section 45A with the same large area as the conventional one for bonding movable contact 5 to EL sheet 40 will interfere with the movement of movable contact 5 because of the properties of adhesive 45.
The inventors thus prepare five types of holding section 45A, namely, holding section 45A measuring 2.0 mm, 2.4 mm, 2.8 mm, 3.2 mm, and 3.6 mm across for adhesively holding the foregoing movable contact 5 measuring 4.0 mm across. The respective holding sections 45A holding movable contact 5 are exposed in the environments of 0° C., −10° C. and −20° C. for one hour, then their movements are tested in the foregoing environments respectively. Table 1 shows the result. In this test, holding section 45A is formed in the same thickness as the conventional one, i.e. 15 μm, and inorganic EL sheet having 100 μm thickness is used.
area ratio: area of holding section 45A vs. plane projection area of movable contact 5, AA: tactile feedback similar to that at an ordinary temperature, A: tactile feedback somewhat inferior to that at the ordinary temperature; however, it is no problem in practical use, B: slow tactile feedback, C: almost no tactile feedback.
As table 1 tells that holding sections 45A measuring 2.0 mm and 2.4 mm across exposed in the environments of 0° C., −10° C. offer the tactile feedback free from deterioration in tactile feeling, and the same holding sections 45A having undergone −20° C. environment offer somewhat inferior tactile feedback to that at an ordinary temperature; however, they have no problem in practical use.
The foregoing test has been done by several testers selected out of people who frequently use the portable phone, and the testers operate movable contact 5 in the foregoing environments for comparing the tactile feedback under normal usage. The testers classify their feelings into four groups, i.e. AA: feeling similar to that at an ordinary temperature, A: feeling somewhat inferior to that at the ordinary temperature; however, it has no problem in practical use, B: slow tactile feeling, C: almost no tactile feeling.
Holding section 45A measuring 2.8 mm across undergoes the same test to find this result: holding section 45A exposed at 0° C. offers tactile feeling similar to that at the ordinary temperature, and holding section 45A exposed at −10° C. offers feeling somewhat inferior to that at the ordinary temperature; however, it has no problem in practical use. Holding section exposed at −20° C. offers slow tactile feeling.
These results prove that movable contact 5 adhesively held by holding section 45A measuring 2.8 mm across offers degraded tactile feedback when this movable-contact unit is mounted to the device exposed in the environment of −20° C. for a long time, and the user feels poor operation.
Portable devices such as portable phones are not kept leaving in the pocket under the environment of −20° C. for a long time. Considering this fact, since movable contact 5 held by holding section measuring 2.8 mm across and exposed at −10° C. can offer the tactile feedback practically usable, it can be determined that this movable-contact unit can be used.
On the other hand, movable contact 5 held by holding section measuring 3.2 mm across and exposed at −10° C. offers only slow tactile feedback, and yet, the same one exposed at −20° C. offers almost no tactile feedback. Movable contact 5 held by holding section 45A measuring 3.6 mm across, the same diameter as the conventional one, and exposed at −10° C. or −20° C. offers almost no tactile feedback.
As discussed above, when movable contact 5 measuring 4 mm across is adhesively placed on inorganic EL sheet 40, holding section 45A measuring 2.0-2.8 mm across can appropriately hold movable contact 5. To be more specific, the area of holding section 45A is desirably set at not less than 25% and not greater than 50%, i.e. preferably 49%, with respect to the plane projection area of movable contact 5. On top of that, use of holding section 45A measuring 2.0-2.4 mm across allows the device to be kept leaving in the low temperature environment such as at −20° C. for a long time and to offer the tactile feedback practically usable.
Based on the foregoing result, it can be presumed that holding section 45A measuring less than 2.0 mm across can offer good tactile feedback even in the low temperature environment; however, in this case, the adhesive holding area becomes smaller, so that it must be studied whether or not movable contact 5 can be held steadily in frequent use.
As discussed above, setting an adhesive holding status of movable contacts 5 onto inorganic EL sheet 40 allows movable-contact unit 50 to offer adequate tactile feedback even in the low temperature environment. Elements other than the foregoing ones, e.g. movable contact 5 having a different diameter, inorganic EL sheet 40 having a different thickness, holding section 45A having a different shape can be included in the scope of the present invention as long as they can produce the advantage similar to what is discussed above, namely, setting an adhesive holding status of movable contacts onto an inorganic EL sheet allows the movable-contact unit to offer adequate tactile feedback even in the low temperature environment.
Since the present invention only sets a status of the holding section of the movable contact, no additional components in structure or no additional steps in manufacturing are needed for carrying out the present invention.
The panel switch employing the movable-contact unit of the present invention is formed of an EL sheet, and domed movable contacts held adhesively on the underside of the EL sheet at their top faces directly with adhesive. The panel switch can provide the user with adequate tactile feedback even in a low temperature environment, so that it can be useful as an operating panel of various electronic devices.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-186415 | Jul 2006 | JP | national |
