PANEL SWITCH AND METHOD OF PRODUCING THE SAME

Abstract: The panel switch uses a diaphragm which provides touch feeling when it is operated. To determine the position of the diaphragm (14) it is adhered to the lower surface of a sheet (15) coated with adhesive, and the sheet is adhered onto the insulating substrate (12) to fasten the diaphragm (14). @(16pp Dwg.No.1/8)@

Description: A panel switch and method for making same The present invention relates to a panel switch for operating electronic apparatus and a method for making same, and more particularly to a panel switch for such use, employing a diaphragm in such a manner as to make good use of its resilient nature whereby the operator operates the switch with security. Figures 4 and 5 are a cross-sectional view and an exploded view showing a conventional panel switch. The switch has an insulated substrate 2 on which a first contact point la and a second contact point 1b are formed. The reference numeral 3 denotes a spacer having a through hole 3a. The spacer 3 has adhesive layers on opposite sides, and accommodates a spherical or cylindrical resilient metal diaphragm 4. The diaphragm 4 is covered with an elastic sheet 5. The reference numeral 7 denotes a casing which holds a press button 6. The diaphragm 4 keeps contact with the second contact point 1b. For operation, an operator pushes the press button 6 so that the diaphragm 4 is pressed and comes into contact with the contact point la through the sheet 5, thereby effecting electrical connection between the contact points la and 1b by way of the diaphragm 4. This type of panel switch has the following disadvantages: One is that the spacer 3 is indispensable for maintaining the diaphragm 4 and cannot be omitted. The cost of the spacer is reflected in the production cost. Another disadvantage is that the diaphragm 4 must be individually inserted into the apertures of the spacers 3, thereby consuming time and labor. In addition, the boring of the apertures produces chips, dirt and adhesive remains, which are likely to cause poor contact between the diaphragm 4 and the contact points 1a, 1b. From JP-A 58 166 619 a panel switch is known comprising an insulated substrate having at least a pair of contact points, a diaphragm secured to one of the contact points and being connectable to the other contact point so as to effect electrical connection between the two contact points, a sheet for covering the diaphragm and securing the diaphragm to the substrate with an adhesive layer formed on the under-surface of the sheet, and an operating section for pressing the diaphragm. A process for making such a panel switch comprises the steps of preparing a tape having adhesive layers on one side and joining the tape to a hoop of resilient diaphragm units, and securing the diaphragm units to a substrate at a contact point. It is the object of the invention to provide a reliable panel switch capable of economical production and an economic production process of the same. Such a panel switch and a process by which such a panel switch can be produced are the subject-matters of the claims. The present invention will be described by way of an example shown in the drawings: Figure 1 is a cross-sectional view showing a panel switch according to the present invention; Figure 2 is an exploded view showing a main portion of the panel switch of Figure 1; Figure 3 is a diagrammatic view showing the steps of fabricating a panel switch according to the present invention; Figure 4 is a cross-sectional view showing a conventional panel switch; and Figure 5 is an exploded view showing a main portion of the conventional panel switch of Figure 4. Referring to Figures 1 and 2, the panel switch is provided with an insulated substrate 12 having contact points 11a, 11b. The panel switch is provided with a spherical or cylindrical resilient metal diaphragm 14, which is connected to the contact point 11b. The reference numeral 15 denotes an elastic sheet having an adhesive layer on one side. The sheet 15 is attached to the diaphragm 14 and also to the substrate 12 so that the diaphragm 14 is united with the substrate 12. The panel switch is provided with a press button 16 held by a casing 17. The button 16 is suspended in such a posture as to be in abutment with the diaphragm 14 through the sheet 15. The casing 17 and the press button 16 constitute an operation section. In operation, an operator presses the press button 16 which then pushes the diaphragm 14 through the sheet 15. In this way the diaphragm 14 comes into contact with the contact point 11a, thereby effecting electrical connection between the contact points 11a and 11b through the diaphragm. The adhesive to be coated on the sheet 15 should be selected from substances which does not impair the resiliency of the diaphragm 14. Each diaphragm 14 has a central aperture 25 in the center. When the diaphragm 14 is pressed against the contact point 11a, the peripheral edge of the central aperture 25 is more surely placed in contact with the contact point lla than otherwise. This secures a reliable switch. The reference numeral 26 denotes an adhesion-prohibiting layer formed on the under-surface of the sheet 15 by printing or by joining another cover sheet. This adhesion-prohibiting layer 26 protects the peripheral edge of the central apertures 25 and the contact point lla from becoming stained with an adhesive, thereby securing the contact between the diaphragm 15 and the contact point lla. In the illustrated embodiment a band type of adhesion-prohibiting layer 26 is used, but the shape is not limited to it if the adhesion-prohibiting layers 26 can cover the respective central apertures 25. Instead of using the adhesion-prohibiting layer 26, an alternative method is to dispense with the coating of an adhesive at the spots of diaphragm that correspond to the central apertures 25. When the adhesion-prohibiting layer 26 of a band type is used, the advantage is that the air trapped in the diaphragm 14 is allowed to escape when the diaphragm 14 is pressed against the contact point 11a, thereby enabling the operator to feel assured of the operability of the switch. Referring to Figure 3, the process of fabricating the panel switch described above will be described: Figures 3(a), (b), (c), and (d) respectively show a tape having its releasable sheet removed and having an adhesion-prohibiting layer 26 attached, a long hoop-like diaphragm to which the tape is attached, tape pieces cut for each unit diaphragm, and an insulated substrate 12 on which the unit diaphragm is attached. As shown in Figures 3(a) to (d), there are prepared a hoop-like diaphragm 20 of a spherical or cylindrical shape, and a tape 21 lined with an adhesive layer covered with a protective releasable sheet 22. The releasable sheet 22 is designed to protect the adhesive layer of the tape 21 from dirt. The insulated substrate 12 is provided with several pairs of contact points 11a and 11b. The tape 21 will be referred to as the sheet 15 at the later stage. The tape 21 is provided with an adhesion-prohibiting layer 27 having a smaller width than that of the tape 21, and is attached to the tape 21 so as to cover the respective central apertures 25 of the hoop-like diaphragm 20 when the tape 21 is overlaid on the hoop-like diaphragm 20. Instead of using the adhesion-prohibiting layer 27, an alternative way is to cover the adhesive layer by printing or with any other medium. The panel switch is fabricated in the following manner: First, the protective releasable tape 22 is removed from the tape 21, so as to attach the tape 21 to the hoop-like diaphragm 20. Then the tape 21 is cut into tape pieces for each unit diaphragm as shown in Figure 3(c). From this stage the tape pieces are referred to as sheets 15, and the unit diaphragms 20 are sucked by a vacuum device or any other similar automatic device, and bridge portions A thereof are cut. Each unit diaphragm is placed on the contact point 11b on the substrate 12, and secured to the substrate 12 by the sheet 15. Then the substrate 12 with the diaphragm 14 is united with the casing 17 having the press button 16. Preferably, after the panel switch is finished, the releasable tape 22 can be again attached to the tape 21 after it has been joined to the hoop-like diaphragm 20, and removed therefrom when the unit diaphragms 14 are secured to the insulated substrates 12. As evident from the foregoing description, the diaphragm is secured to the insulated substrate with the sheet without the use of any spacer. The non-use of the spacer saves the cost and labor, thereby providing an economical panel switch. The diaphragm is prepared in a continuous hoop, and after the adhesive tape is attached thereto, the diaphragm is cut into units, and the unit diaphragms each are covered with the sheets which are secured to the insulated substrate. As a result, the following advantages have been achieved: (1) Until the unit diaphragm is sucked by an automatic device, it is kept continuous as a hoop, thereby avoiding the production of panel switches having two diaphragms attached to. (2) Since the diaphragms are individually united with the casings, the same process can be applied regardless of variations in the optional arrangement of keys on equipment. (3) The method of the invention eliminates the use of any spacer, and each diaphragm is independent of each other. Thus, modifications and variations in design and shape can be freely done, thereby speeding up the production and saving on the cost.

Claims: Panel switch comprising a) an insulated substrate (12) having at least a pair of contact points (11a, 11b), b) a diaphragm (14) secured to one of the contact points (11b) and being connectable to the other contact point (11a) so as to effect electrical connection between the two contact points (11a, 11b), c) a sheet (15) for covering the diaphragm (14) and securing the diaphragm (14) to the substrate (12) with an adhesive layer formed on the under-surface of the sheet (15), and d) an operating section (16,17) for pressing the diaphragm (14), characterized in that e) the diaphragm (14) has a central aperture (25), and f) the sheet (15) has no adhesive at a stripe region including a spot that corresponds to the central aperture (25) of the diaphragm (14). Process for making a panel switch, the process comprising the steps of a) preparing a tape (21) having adhesive layers on one side and joining the tape (21) to a hoop of resilient diaphragm units (20), and b) securing the diaphragm units (20) to a substrate (12) at a contact point (11b), characterized by the following steps: c) before joining the tape (21) to the hoop of diaphragm units (20), an adhesion-prohibiting stripe layer (26) having a smaller width than that of the tape (21) is formed between the adhesive layers, d) the diaphragm units (20) having central apertures (25), e) the tape (21) is joined to said hoop of diaphragm units (20) so that the central apertures (25) are covered with the adhesion-prohibiting stripe layer (26), f) the joined tape (21) and hoop of diaphragm units (20) are cut into tape pieces for each diaphragm unit (20), and g) each diaphragm unit (20) is secured to the substrate (12) individually.

Inventors: OGASAWARA NOBUO, SANTO KOUICHI, OGASAWARA, NOBUO, SANTO, KOUICHI
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1989
Main classification: H01H13
IPC codes: H01H13, H01H11