Keyboard switch for notebook type computer or the like

• US 5,894,117 A
• Filed: 07/17/1997
• Issued: 04/13/1999
• Est. Priority Date: 12/26/1996
• Status: Expired due to Fees

• Current Assignee: SMK Corporation
• Original Assignee: SMK Corporation
• Inventors: Kamishima, Osamu
• Primary Examiner(s): Luebke, Renee S.
• Application Number:
  US08/893,999
• Time in Patent Office: 635 Days
• Field of Search: 200/344
• US Class Current: 200/344
• CPC Class Codes: H01H 2219/028 Printed information
• CPC Class Codes: H01H 2221/068 having a not operable condition
• CPC Class Codes: H01H 2227/036 Minimise height
• CPC Class Codes: H01H 3/125 using a scissor mechanism as stabiliser

Abstract

A keyboard switch having a keytop which is displaced vertically by a cross link that comprises a first link member and a second link. A front edge side of the keytop comes slightly lower than its rear edge side and the cross link is configured so that the pushdown stroke is greater on the rear edge side than on the front edge side and that the top face of the keytop. When the keytop is pushed down completely, it comes almost parallel to a frame of the keyboard switch. This configuration, when adopted, for example, to a notebook type personal computer with a lid, results in sliding an elastic portion which holds up the keytop in interlock with the lid closing, thus the keytop, as a whole horizontal. This configuration wherefore allows achieving otherwise contradictory effects of a great stroke when the lid is opened and a thinner notebook when the lid is closed. Further, the top surface of the keytop when it becomes nearly parallel, facilitates character printing improving the printing yield.

Claims

1. A keyboard switch comprising:

a switch holding frame;

a keytop having a top face, a front edge side and a rear edge side, said keytop being positioned at an uppermost position when the keyboard switch is not activated and at a lowermost position when the keytop is pressed vertically down for activation of the keyboard switch, said front edge side of the keytop being positioned lower than the rear edge side when the keytop is in the uppermost position, forming a slant in the top face from the rear edge side to the front edge side;

a crosslink including,

a first link member having a first end connected to a first portion of the keytop and a second end connected to a first portion of the switch holding frame, and

a second link member having a first end connected to a second portion of the keytop, and a second end connected a second portion of the switch holding frame; and

a rotatable fulcrum connecting the first link member and the second link member, the rotatable fulcrum being positioned nearer to the front edge side of the keytop as compared to a midpoint position between the first and second ends of at least one of the first and second link members, enabling the top face of the keyboard to become almost parallel to the switch holding frame when the keytop is pressed down to the lowermost position for activation of the keyboard switch.

2. The keyboard switch according to claim 1, wherein said keytop has a bottom face, said keyboard switch further comprising:

a membrane switch sheet on the switch holding frame;

an electrode at a predetermined position on the membrane switch sheet; and

means for deforming in contact with the membrane sheet and a projection from the bottom face of the keytop, said means for deforming keeping said keytop in the uppermost position when the keyboard switch is not activated and deforming when the keytop is pushed down for activation of the keyboard switch to short-circuit the electrode on the membrane switch sheet,

said keytop including a concave portion on the bottom face proximate the projection, said concave portion housing said means for deforming when said keyboard switch is in a non-operational position, different from the uppermost position of the keytop.

3. The keyboard switch according to claim 2, wherein said switch holding frame and keytop are displaced a predetermined lateral distance with respect to the membrane switch sheet when said keyboard switch is in the non-operational position, enabling said means for deforming to be housed in said concave portion.

4. The keyboard switch according to claim 3, wherein said predetermined lateral distance is equivalent to a width of said means for deforming taken in a direction in which said switch holding frame and keytop are displaced through said predetermined lateral distance with respect to the membrane switch sheet.

5. A keyboard switch comprising:

a switch holding frame;

a keytop having a top face, a front edge side and a rear edge side, said keytop being positioned at an uppermost position when the keyboard switch is not activated and at a lowermost position when the keytop is pressed vertically down for activation of the keyboard switch, said front edge side of the keytop being positioned lower than the rear edge side when the keytop is in the uppermost position, forming a slant in the top face from the rear edge side to the front edge side;

a crosslink including,

a first link member having a first end connected to a first portion of the keytop and a second end connected to a first portion of the switch holding frame, and

a second link member having a first end connected to a second portion of the keytop, and a second end connected a second portion of the switch holding frame; and

a rotatable fulcrum connecting the first link member and the second link member,

the first portion of the keytop being proximate the rear edge side and the second portion of the keytop being proximate the front edge side, and at least one of,

i) the length between the rotatable fulcrum and the first end of the first link member being greater than both the length between the rotatable fulcrum and the second end of the first link member and the length between the rotatable fulcrum and the first end of the second link member, and

ii) the length between the rotatable fulcrum and the second end of the second link member being greater than both the length between the rotatable fulcrum and the first end of the second link member and the length between the rotatable fulcrum and the second end of the first link member.

6. The keyboard switch according to claim 5, wherein said keytop has a bottom face, said keyboard switch further comprising:

a membrane switch sheet on the switch holding frame;

an electrode at a predetermined position on the membrane switch sheet; and

means for deforming in contact with the membrane sheet and a projection from the bottom face of the keytop, said means for deforming keeping said keytop in the uppermost position when the keyboard switch is not activated and deforming when the keytop is pushed down for activation of the keyboard switch to short-circuit the electrode on the membrane switch sheet,

said keytop including a concave portion on the bottom face proximate the projection, said concave portion housing said means for deforming when said keyboard switch is in a non-operational position, different from the uppermost position of the keytop.

7. The keyboard switch according to claim 6, wherein said switch holding frame and keytop are displaced a predetermined lateral distance with respect to the membrane switch sheet when said keyboard switch is in the non-operational position, enabling said means for deforming to be housed in said concave portion.

8. The keyboard switch according to claim 7, wherein said predetermined lateral distance is equivalent to a width of said means for deforming taken in a direction in which said switch holding frame and keytop are displaced through said predetermined lateral distance with respect to the membrane switch sheet.