AU618061B2

AU618061B2 - Operating key switch unit

Info

Publication number: AU618061B2
Application number: AU28734/89A
Authority: AU
Inventors: Yoshihiro Hattori; Takashi Murakami
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1988-06-13
Filing date: 1989-01-24
Publication date: 1991-12-12
Anticipated expiration: 2009-01-24
Also published as: AU2873489A; JPH0738288B2; CA1316006C; GB2219691A; GB2219691B; JPH01313820A; GB8901123D0

Description

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AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION Form

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: i":1 Application Number: Lodged: Ci *r t 4 to

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Ott Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT

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ii t i i j 1; Name of Applicant: Address of Applicant: MITSUBISHI DENKI KABUSHIKI

KAISHA

2-3 MARUNOUCHI 2 CHOME

CHIYODA-KU

TOKYO 100

JAPAN

GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Actual Inventor: Address for Service: Complete Specification for the invention entitled: OPERATING KEY SWITCH UNIT The following statement is a full description of this invention including the best method of performing it known to me:- OPERATING KEY SWITCH UNIT BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an operating key switch unit having a waterproof case with an electric circuit enclosed therein, and a plurality of key switch buttons for external operation exposed from the front of the case.

Description of the Prior Art i A conventional operating key switch unit will now be 10 described with reference to Figs. 1 to 4. Fig. 1 is a Iperspective view showing an appearance of the switch unit; Fig. 2 is a sectional view taken on line II-II of Fig. 1; Fig. 3 is a partially enlarged view of Fig. 2; and Fig. 4 is a front view of ajpanel.aw 4beh. In these figures, the 15 reference numeral 1 denotes a waterproof case molded from a resin; numeral 2 denotes a display opening formed in the j front indicated at la of the case 1; numeral 3 denotes a *button hole formed in a plural number (twelve in the drawings) in the front la of the case 1; numeral 4 denotes a printed circuit board mounted in the case 1 using bolts 5; and numeral 6 denotes a display portion inserted in the display opening 2 between a front-side surface 4a of the printed circuit board 4 and the case front la. Numeral 7 denotes a aemel switch Ainserted between the front-side surface 4a of the printed circuit board 4 and the case front la, and key

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r switch buttons 8 for external operation exposed respectively from the button holes 3 are formed integrally with the switch panel 7 using an elastic material. Numeral 9 denotes an electroconductive contact of each key switch button 8 integral with the switch panel 7, the electroconductive contact 9 being provided in a recess 7a.

Numeral 10 denotes a contact printed on the front-side surface 4a of the printed circuit board 4 in an opposed 1 relation to each electroconductive contact 9. Numeral 11 i denotes an electronic part mounted on a back-side surface 4b of the printed circuit board 4.

The operation of the conventional key switch unit of the above construction will now be expl l.ed. The switch panel 7 is put on the printed circuit board 4 having J the electronic part 11 and fixed to the case 1 with b.Its As a result, the key switch buttons 8 of the switch B panel 7 are exposed from the button holes 3 of the case so that they can be operated from the exterior.

S .The contacts 10 on the printed circuit board 4 and the electroconductive contacts 9 of the switch panel 7 S"0jointly form a switch structure. Both contacts 9 and i are normally not in contact with each other as shown in Fig. 3, but when a key switch button 8 is depressed, the switch panel 7 is deformed through the associated recess 7a, so that both contacts are in contact with each other and as a result the contents of operation are displayed on i the display portion 6.

According to the conventional operating key switch unit described above, the switch panel 7 is integrally formed using an elastic material and it is sandwiched between the front-side surface 4a of the printed circuit board 4 and the inner surface of the case front la, to thereby prevent the invasion of water from the button holes 3 to the exterior of the switch panel 7, namely the interior of the case 1, through a surrounding contact portion 7b of the switch panel 7. However, the surrounding contact portion 7b of the switch panel 7 is held by a -2- N2 contact pressure induced by only the urging force of the bolts 5, so when the switch panel 7 is deformed in response to depression of a key switch button 8, there occurs a change in contact pressure of the surrounding contact portion 7b, that is, a uniform contact pressure is not obtained, resulting in that water enters the interior of the case 1 through the surrounding contact portion 7b, thuS causing the contacts 9,10 and the electronic part 11 to be corroded. Further, if the mounting pitch of the bolts 5 is made smaller to increase the contact pressure of the switch panel 7, the resulting increase in the number of bolts causes an increase in time required for the assembling operation, thus leading to increase of cost.

~According to the present invention there is an operating key switch unit wherein an electric circuit is enclosed in a waterproof case and a plurality of key switch buttons for external operation are exposed from the front of the case, said operating key switch unit comprising a printed circuit board mounted in said case with bolts to partition the interior of the case into a front side and a S'back side, with contacts being formed on the front-side board surface which contacts are opposed to i i :electroconductive contacts of said key switch buttons, and with electronic parts being mounted on the back-side board Ssurface, and also having a switch panel with which said key r (11 switch buttons are integrally formed, said key switch buttons using an elastic material, and said switch panel being inserted between the front-side surface of said printed circuit board and the inner surface of the front of said case, said operating key switch unit further comprising a first contactor projecting from the inner i surface of the front of said case substantially in the same direction as the operating direction of said key switch buttons and disposed annularly in a surrounding relation to the key switch buttons, and a second contactor formed integrally with said switch panel which is disposed annularly with respect to the key switch buttons and 1' BA2 3forming a U-shaped section having vertical legs wherein a top part of the vertical legs has a more restricted separation than a bottom part of the vertical legs so as to maintain an hermatic seal for the plurality of key switch buttons at all times by continuously contacting the first contactor between the vertical legs of the top part of the U-shaped section of the second contactor.

Said first contactor may comprise a convex portion, while said second contactor may comprise a concave groove engaged with said convex portion.

Alternatively said first contactor may comprise a I concave groove, while said second contactor may comprise a convex portion engaged with said concave groove.

S* Said first contactor may comprise a convex portion the tip end of which reaches the front-side surface of said printed circuit board, while said second contactor may comprise a rib which is in contact with the inner .0 peripheral surface of said first contactor.

Alternatively said first contactor may comprise a V rib, while said second contactor may comprise a convex portion whose outer peripheral surface is in contact with S j said rib.

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BRIEF DESCRIPTION OF THE DRAWINGS: In order that the invention may be more fully described, i embodiments of the invention will be described by way of j example only with reference to the accompanying drawings in which: Fig. 1 is a perspective view showing an appearance of a conventional key switch unit; Fig. 2 is a sectional view taken on line II-II of Fig. i; Fig. 3 is a partially enlarged view of Fig. 2; Fig. 4 is a front view of a switch panel; Fig. 5 is a side view, in longitudinal section, showing an embodiment of the present invention; i Fig. 6 is a partially enlarged view of Fig. Y .IS -4i Fig. 7 is a front view of a switch panel; Fig. 8 is a right-hand side view of Fig. 7; Fig. 9 is a side view, in longitudinal section, showing another embodiment of the present invention; Fig. 10 is a partially enlarged view of Fig. 9; Fig. 11 is a front view of a panel switch; and Fig. 12 is a right-hand side view of Fig. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to Figs. 5 to 8. Fig. 5 is a sectional view similar to Fig. 2; Fig. 6 is a partially enlarged view of Fig. 5; Fig. 7 is a front view of a switch panel; and Fig. 8 is a right-hand side view of Fig. 7. In these figures, portions which are the same as or equivalent to those of the foregoing conventional switch unit are indicated by the same reference numerals and will not be explained here. And in these figures the reference numeral $too c, 7A denotes a switch panel integrally formed using an 9 elastic material; numeral 12 denotes a convex portion formed on the inner surface of a case front la, the convex portion 12 extending annularly along the marginal portion of the switch panel 7A; and numeral 13 denotes a concave groove formed annularly in the marginal portion of the switch panel 7A, in which groove is fitted the convex portion 12.

l ,Thus, the convex portion 12 of the case front la and the concave groove 13 of the switch panel 7A are fitted together. This is advantageous in that even when the .14switch panel i saiteh 7A is deformed upon depression of a key switch button 8, there will be no change in contact pressure between the convex portion 12 and the concave groove 13 because both are in contact with each other in the same direction as the operating direction. Therefore, there is no fear of the pane\ invasion of water to the exterior of the paaL switch 7A, namely, the interior of the case 1.

Although in the above embodiment the convex portion 12 and the concave groove 13 serve as one contactor and the S' other contactor, respectively, they may be reversed.

Now, another embodiment of the present invention will ,be described with reference to Figs. 9 to 12. Fig. 9 is I ti a sectional view similar to Fig. 5; Fig. 10 is a partially enlarged view of Fig. 9; Fig. 1.1 is a front view of a panel switch; and Fig. 12 is a right-hand side view of Fig. 11, 15 in which figures portions which are the same as or equivalent to those in the previous embodiment are indicated by the same reference numerals and will not be explained here. In these figures, the numeral 7B denotes a paei switch integrally formed using an elastic material, and numeral 12A denotes a convex portion formed on the inner surface of the case front la, the convex portion 12A being located annularly panc\ surrounding the outer periphery of the pane switch 7B and in contact with a front-side surface 4a of the printed circuit board 4. Numeral 14 denotes a rib formed annularly on the outer periphery of the paiet switch.7B and in contact with the inner peripheral surface of the convex portion 12A.

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SI Although in this embodiment the convex portion 12A and the rib 14 serve as one and the other contactor, respectively, they may be reversed.

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Claims

2. An operating key switch unit according to Claim i, wherein said first contactor comprises a convex portion, while said second contactor comprises a concave groove engaged with said convex portion. -8- k'
3. An operating key switch unit according to Claim 1, wherein said first contactor comprises a concave groove, while said second contactor comprises a convex portion engaged with said concave groove.
4. An operating key switch unit according to Claim 1 or 2, wherein said first contactor comprises a convex portion the tip end of which reaches the front-side surface of said printed circuit board, while said second contactor comprises a rib which is in contact with the inner peripheral surface of said first contactor. An operating key switch unit according to Claim 1 or 3, wherein said first contactor comprises a rib, while said second contactor comprises a convex portion whose outer peripheral surface is in contact with said rib. 6, An operating keyswitch substantially as hereinbefore described and illustrated with reference to Figures 5 to 12 of the eccompanying drawings. i 4* I DATED THIS 5TH DAY OF AUGUST, 1991. MITSUBISHI DENKI KABUSHIKI KAISHA By Its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia. 9 i 01 h A*i 4