Capacitance type switch having dust-free interior

• US 4,453,061 A
• Filed: 06/09/1982
• Issued: 06/05/1984
• Est. Priority Date: 06/09/1981
• Status: Expired due to Fees

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Tamura, Ryutaro
• Primary Examiner(s): Shepperd, John W.
• Assistant Examiner(s): Kidorf, Renee S.
• Application Number:
  US06/386,613
• Time in Patent Office: 727 Days
• Field of Search: 200/302, 200/306, 200/296, 200/159 B, 200/DIG. 1, 340/365 C
• US Class Current: 200/306
• CPC Class Codes: H01H 9/047 provided with venting means

Abstract

A novel capacitance type switch has a completely dust proof structure and ensures smooth switch operation. The switch comprises a stem supporting a movable contact and slidably inserted into a switch case; a plurality of holes formed in the switch case around the stem so as to permit air to pass therethrough into and out from the switch case; a cover surrounding the holes and in intimate contact with the switch case so that the inside of the switch case can communicate with the inside of the cover; the cover being made of a resilient material; and a dust filter made of a seal material interposed between the inside of the switch case and the atmosphere.

Claims

1. A capacitance type switch comprising:

a stem carrying a movable contact and slidably inserted into a switch case;

a plurality of holes formed in said switch case in an area around said stem so as to permit air to pass into and out from said switch case;

a resilient cover held to said stem and surrounding said holes, said cover being in air-tight contact with said switch case so that the inside of said switch case can communicate with the inside of said cover through only said holes; and

a filter made of a seal material and interposed between the inside of said switch case and the atmosphere.

2. The capacitance type switch as defined in claim 1 wherein said filter material is foamed polyurethane.

3. A capacitance tpye switch comprising:

a stem carrying a movable contact and slidably inserted into a switch case;

a plurality of holes formed in said switch case in an area around said stem so as to permit air to pass into and out from said switch case;

a resilient cover held to said stem and surrounding said holes, said cover being held in intimate contact with said switch case so that the inside of said switch case can communitcate with the inside of said cover;

engaging plates disposed on the side walls of said switch case, said engaging plates being spaced from said switch case to form holes for the passage of air into said switch case;

said engaging plates of said switch case engaging a panel supported in spaced relation on a printed circuit board; and

a filter made of a seal material placed around said switch case and interposed between said printed circuit board and said panel.

4. A capacitance type switch comprising:

a stem a carrying movable contact and slidably inserted into a switch case;

a step portion formed on the surface of said switch case and having holes formed therein to pentetrate to the inside of said switch case;

a cover made of a resilient material and having one end held to said stem and the other end fitted in air-tight relation with the outer periphery of said step portion;

the inside of said switch case being adapted to communicate with the inside of said cover via said holes only;

gap holes formed on the side walls of said switch case; and

a filter material formed of a seal material and interposed in said gap holes between the inside of said switch case and the atmosphere.

5. The capacitance type switch as defined in claim 4 wherein said filter material is made of foamed polyurethane.

6. A capacitance type switch comprising:

a stem carrying a movable contact and slidably inserted into a switch case;

a step portion formed on the surface of said switch case and having holes formed therein to penetrate to the inside of said switch case;

a cover made of a resilient material and having one end in intimate contact wih said stem and the other end fitted to the outer periphery of said step portion;

the inside of said switch case being adapted to communicate with that of said cover via said holes;

engaging plates for permitting the external air to pass therethrough, said engaging plates being disposed on the side walls of said switch case and spaced therefrom to form holes for the passage of air into said switch case;

said engaging plates of said switch case being anchored to a panel supported on a printed circuit board with a predetermined gap between them; and

a filter material made of a seal material placed around said switch case and interposed between said printed circuit board and said panel.