Mechanical keyboard with membrane switch arrray |
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| 申请号 | EP84305716 | 申请日 | 1984-08-22 | 公开(公告)号 | EP0157035A3 | 公开(公告)日 | 1987-03-18 |
| 申请人 | CHERRY ELECTRICAL PRODUCTS LIMITED; | 发明人 | Ellson, Allan; | ||||
| 摘要 | A key actuated membrane switch comprises a key operated switch actuating member 101 in the form of a key module and a membrane switch panel 111. The switch panel consists essentially of three membranes (112, 113, 114), one on top of the other, sealed together with adhesives. The upper and the bottom membranes (112, 113) are each continuous and each has at least one contact (115) and a respective conductor formed on its interior surface. The middle membrane (114) has at least one aperture (117) which defines a switch cell. The two contacts (115) are coaxially aligned with the aperture so that pressure on the upper membrane (112) along the axis of the aperture, causes the two contacts to come together and make a circuit. The membrane package is mounted, prefer- ebly by an adhesive, on a rigid base 120. Pressure is selectively applied to the upper membrane by means of the key operated switch actuating member (101) via the agency of a cantilevered single-arm spring (104) which acts to apply leverage on the upper membrane (112) when the actuating member (101) is operated. The spring has a first portion which extends from the supported end of the spring in a plane parallel to the plane of the upper membrane to the vertical axis of the said contacts, and a (Continuation next page) second portion which extends upwards, at an angle, to the actuating plunger (108) of the actuating member. When the latter is actuated the spring (104) is flexed downwards and hinges during the first part of its movement about its supported end, thereby displacing the bend or "knee" (107) intermediate the two portions of the spring arm. The knee therefore applies pressure, with mechanical advantage, on the upper membrane (112). When the contacts come together. no further displacement of the knee (107) is possible and any further displacement of the free end of the spring causes flexing to take place at the knee and in the second portion of the spring. In a preferred arrangement the said spring (104) is supported by means of a dog-leg portion (105) which is entered into a vertical slot (106) provided on the base of the actuating member (101). The slot contains facing ribs (121, 122) which cause the dog-leg portion to flex as it is pushed into the slot. This flexing results in a frictional force being exerted by the dog-leg portion on the ribs which serves to prevent the spring from falling out of the slot. Any tendency for this to happen is also counteracted by the leverage exerted by the spring (104) as it attempts to rock about its "knee" during overtravel of the spring. Also in the preferred arrangement the actuating member (101) is fastened onto the upper membrane (112) by an adhesive. The above arrangement is particularly intended as a keyboard switch. | ||||||
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