Abstract: A keyboard unit having a base plate, and a plurality of key switches provided on the base plate. Each of the key switches has an electric contact provided within a membrane sheet on the base plate, an elastic dome portion formed on the base plate so as to cover the electric contact, a bearing portion provided on base plate, and a key cap having a support shaft which engages the bearing portion, and an engaging portion which engages the dome portion. When the key cap is depressed, the dome portion is elastically deformed so that an inner surface of the dome portion presses against the electric contact, and when the key cap is not depressed, deformation of the dome portion is removed so that the inner surface of the dome portion is separated from the electric contact and the key cap is pushed up by the dome portion.

Abstract: A keyboard switch having a membrane contact point sheet and a push button key for pressing down a contact point portion of the membrane contact point sheet, further includes a housing including a base portion and a casing portion, a key top which is slidably supported in the casting portion and has a contact point pressing portion projecting toward the base portion in an area extending outside a periphery of the casing portion, and a biasing member for biasing the key top toward a home position. The membrane contact point sheet is disposed on the base portion of the housing so that the contact point portion is confronted with the contact point pressing portion, and is formed in a three-layered structure, including an upper contact point sheet, a spacer, and a lower contact point sheet. The contact point portion has a window hole provided in the spacer.

Abstract: A push-button switch comprises a fixed electrode; a movable electrode disposed opposite to the fixed electrode; a key housing having a tubular spring retainer, and an annular guide wall surrounding the tubular spring retainer and having a stopping flange, a coil spring received in the tubular spring retainer, and a key for operating the movable electrode through the coil spring. The coil spring has a large coil section, a middle extension coil section, and a small compression coil section having a projecting part. The tubular spring retainer is provided with a protrusion on the inner circumference thereof. When the key is depressed to close the switch, the projecting part of the coil spring is forced to move down over the protrusion in a snap motion, and the projecting part is forced to move up over the protrusion by the contractive force of the middle extension coil section and the recoiling force of the small compression coil section of the coil spring when the key is released.

Abstract: A luminous element holding structure for an illuminated key switch arrangement includes a key having a transparent window, a housing for containing switch operating members, the housing having a recess, a flange and a pair of catches, a holding plate provided with through holes each for receiving the lower portion of the housing, a base plate, a switch element having pairs of switch contacts, and pairs of fixed electrodes each for conducting current to a luminous element, and a luminous element holder disposed in the recess of the housing. The lead wires of a luminous element are inserted forcibly in through holes formed in a pair of conductive members of the luminous element holder so that the luminous element is held firmly by the luminous element holder. The luminous element holder is set in the recess of the housing and the key is combined with the housing so that the transparent window is located opposite to the luminous element held on the luminous element holder.

Abstract: A keyboard comprises a base plate carrying contact circuits and provided with a plurality of holes, and a key holding frame integrally provided with key housings for receiving keys, vertically flexible posts for determining the lateral position of the base plate relative to the key holding frame, horizontally flexible posts for determining the lateral position of the base plate relative to the key holding frame in cooperation with the vertically flexible posts, fixed posts for determining the longitudinal position of the base plate relative to the key holding frame, and hooks for determining the vertical position of the base plate relative to the key holding fame and to hold the base plate firmly on the key holding frame.

Abstract: A keyboard of a membrane contact type comprises a membrane contact unit having movable contacts, fixed contacts disposed respectively opposite to the movable contacts, and a printed wiring board having electronic circuit elements and provided with printed wiring lines. The membrane contact unit comprises a flexible, insulating, membranous substrate having movable contacts formed in a movable contact section and fixed contacts formed in a fixed contact section demarcated by a folding line, in the same surface as the movable contacts and arranged symmetrically about the folding line. First and second wiring lines connect the movable contacts and the fixed contacts respectively in a predetermined connecting pattern. A first terminal section having first terminals is connected respectively to the first wiring lines, and a second terminal section having second terminals is connected respectively to the second wiring lines. The first and second terminal sections are formed near the folding line.