Computer graphics processing and selective visual display system – Display peripheral interface input device – Including keyboard
Reexamination Certificate
2001-02-26
2003-07-08
Shankar, Vijay (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Including keyboard
C345S169000
Reexamination Certificate
active
06590565
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-109541, filed Apr. 11, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a keyboard unit having pop-up key-tops and an electronic apparatus incorporating the keyboard unit.
Recently, in the market involving portable computers, there is a demand for forming the portable computers thinner and more compact to facilitate to carry them. To satisfy the demand, it is an urgent necessity to make thin main components such as a main body having a keyboard unit, a liquid crystal display unit, etc.
A keyboard unit incorporated in the main body of a portable computer has a number of key-tops to be operated by the fingers of the operator. Each of the key-tops is vertically movably supported by a key-top support mechanism of a pantograph type located on a keyboard base. The key-top support mechanism has a pair of link levers. These link levers are assembled into an X-shaped structure, and connected so that they can pivot relative to each other. A sheet switch is provided on the keyboard base. This switch has a number of movable contacts and a number of stationary contacts. The movable contacts are opposed to the stationary contacts below the key-tops.
In a keyboard unit of this type, to realize comfortable input operability, it is necessary, when a finger has pushed a key-top, to enable the operator to clearly feel a click. To this end, the conventional keyboard unit incorporate an elastically deformable pressing member interposed between each key-top and the switch. This pressing member is formed of a flexible rubber material such as silicone rubber, and is cup- or dome-shaped such that it opens to the switch. Each pressing member always upwardly presses a corresponding key-top away from the switch. Upper portions of the pressing members form projections for pressing the respective movable contacts of the switch.
Accordingly, when a finger pushes a key-top, a corresponding pressing member is depressed to thereby cause the finger to feel a click, and the projection of the pressing member presses a corresponding movable contact of the switch. As a result, the movable contact is brought into contact with a corresponding stationary contact, thereby closing the switch. The keyboard unit, in turn, outputs an input signal indicating that a desired key-top has been pushed.
In a keyboard unit for a portable computer, it is necessary to secure the stroke amount of each key-top so as to cause the operator to clearly feel that each key-top has been pushed. However, the stroke amount of each key-top significantly influences the thickness of the keyboard unit. The larger the stroke amount, the thicker the keyboard unit. The increase of the stroke amount is a hindrance to the thinning of the computer.
A so-called pop-up keyboard unit is known as an improvement developed in light of the above. In this improvement, key-tops are depressed and superposed on the switch when the computer is not used, and are protruded upwardly only when the computer is used.
For example, Japanese Patent Application KOKAI Publication No. 8-54964 discloses an example of the pop-up keyboard unit. In this keyboard unit, cup- or dome-shaped pressing members are provided on the upper surface of the switch. The switch is supported on a keyboard base so that it can slide between a first position in which the pressing members are positioned below key-top support mechanisms, and a second position in which the pressing members are displaced from the key-top support mechanisms. While the liquid display unit is open, the switch is urged by a spring to the first position. When the liquid display unit is closed, the switch is forcibly slid from the first position to the second position.
When the switch is slid to the first position, the pressing members raise the key-top support mechanisms. Accordingly, the link levers of each key-top support mechanism upwardly pivot on portions thereof connected to the keyboard base, whereby the key-tops are kept in a position in which they are upwardly protruded above the switch by a desired amount.
When, on the other hand, the switch is slid to the second position, the pressing members are displaced from the key-top support mechanisms. Accordingly, the raise of the key-top support mechanisms by the pressing members is released. As a result, the link levers of each key-top support mechanism downwardly pivot on portions thereof connected to the keyboard base, whereby the key-tops are depressed. This structure enables thinning of the keyboard unit while securing the stroke amount of each key-top, which is necessary to depress it.
In the conventional keyboard unit, each pressing member for pressing a corresponding movable contact or causing the operator to feel a click, when a finger pushes a corresponding key-top, is a component separate from the key-top support mechanism. Therefore, the number of components incorporated in the keyboard unit is inevitably large, which results in high cost. Further, since it is necessary to provide the same number of pressing members as the key-tops on the switch, a lot of time and effort are required, which degrades the efficiency of assembly of the keyboard unit.
As an improvement for overcoming this, a keyboard unit is known, in which the link levers of a key-top support mechanism are formed of pressed component parts, and an elastically deformable tongue member for pressing a switch is formed integral with one of the link levers. In this case, the tongue member directly presses the switch when the link levers of the key-top are downwardly pivoted in accordance with the push operation of the key-top. This structure does not require the above-described pressing members of rubber, which results in cost reduction.
However, the tongue member formed of a metal plate has a higher rate of spring than the rubber pressing member, and hence has a strong spring force which causes the tongue member to try to maintain its initial state against a force occurring when the tongue member is brought into contact with the switch. This being so, the operator feels heavy touch when pushing a key-top. In other words, the input operability is degraded.
Furthermore, since the tongue member is formed integral with the link lever by press working, it is necessary to remake a mold for press working in order to change the rate of spring of the tongue member. Thus, it is difficult to change the rate of spring of the tongue member for improving the key touch obtained when pushing each key-top.
In addition, in the conventional pop-up keyboard unit, the flexible rubber pressing member is brought into contact with the key-top support mechanism each time the liquid crystal display unit is opened or closed. Accordingly, it is possible that the pressing member will be degraded or worn out in an early stage.
Also, the rubber pressing member generates a strong frictional force in a portion thereof connected to the key-top support mechanism. Accordingly, high resistance occurs when sliding the switch, with the result that each key-top cannot smoothly be raised or depressed.
BRIEF SUMMARY OF THE INVENTION
It is a first object of the invention to provide a keyboard unit and electronic apparatus of excellent operability, which enable the operator to have nice feeling when pushing each key-top, although they incorporate a structure in which pressing members made of a metal are arranged to press the respective movable contacts of a switch.
It is a second object of the invention to provide a keyboard unit and electronic apparatus of excellent operability, which can easily raise and depress each key-top with a small force of the operator while causing the operator to have nice feeling when they push each key-top.
To attain the first object, there is provided a keyboard unit according to a first aspect. This keyboard unit comprises: a keyboard base; a number of key-tops arranged ab
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Patel Nitin
Shankar Vijay
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