Typewriting machines – Key-board or key lever-actuating mechanism – Including means generating a signal for type selecting or...
Reexamination Certificate
2002-09-19
2004-11-30
Hirshfeld, Andrew H. (Department: 2854)
Typewriting machines
Key-board or key lever-actuating mechanism
Including means generating a signal for type selecting or...
C400S480000, C400S490000, C200S0050EA, C200S512000, C361S689000, C345S168000, C379S368000
Reexamination Certificate
active
06824321
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to keypad assemblies used in electronic devices such as mobile telephones, cordless telephone handsets, hand held computers, or the like, and more particularly to keypad assemblies employing touch detecting apparatus capable of sensing forces applied to keys of the keypad assembly for registering key presses.
Hand held electronic devices such as mobile telephones, cordless telephone handsets, hand-held computers, calculators, and the like, often employ keypads for entry of information and commands.
FIG. 1
illustrates a traditional keypad assembly used in such devices. The keypad assembly
100
includes a circuit board
102
having a plurality of conductors
104
. A keypad
106
is disposed over the circuit board
102
. The keypad
106
includes a plurality of keys
108
consisting of resilient key domes
110
, each providing a contact
112
, positioned over a corresponding conductor
104
of the circuit board
102
. When a force (F) is applied to a key
108
of the keypad
106
, its key dome
110
is collapsed, bringing the contact
112
of the key dome
110
into contact with the corresponding conductor
104
disposed on the circuit board
102
. This contact changes the electrical conductance of the conductor
104
, registering a key press.
Traditional keypad assemblies employ a fixed key layout that is used for all input functions. Consequently, any new or different key assignments must be mapped to the existing key structure. This remapping of key assignments can cause confusion for the user of the electronic device employing the keypad assembly, and is limited by the original layout of the keys of the keypad assembly. Additional flexibility may be obtained by utilizing part of the display of the electronic device to provide key assignment choices to selected keys. This technique is used by the electronic device
200
illustrated in FIG.
2
. The electronic device
200
, in this case a mobile telephone, includes a housing
202
having a keypad assembly
204
and display
206
. The keypad assembly
204
includes one or more dynamic function keys,
208
and
210
, which are positioned directly below the display
206
. The display
206
, in turn, includes areas or regions
212
and
214
positioned adjacent to the function keys
208
and
210
, that are used for displaying functions of the electronic device
200
. In this manner, the function keys
208
and
210
may be used for selecting among various functions displayed in the regions
212
and
214
. However, in most applications, the number of keys available for use as function keys is constrained by the space allotted on the display, since use of the display for displaying functions limits the display area that may be used for other purposes. Consequently, functions typically must be presented in a menu format, which many users find confusing.
In many applications, it would be desirable to provide an electronic device such as a mobile telephone, cordless telephone handset, or the like, having a single piece molded housing or shell, wherein the keyboard assembly is encapsulated within the material providing the housing. For example, electronic devices having this structure may often be manufactured at a substantially lower cost than devices having a conventional multi-piece housing and require less tooling and design time to produce. However, encapsulation of a traditional keypad assembly has proven problematic. As shown in
FIG. 3
, when a traditional keypad assembly
300
is encapsulated in a molded housing, resin is injected into the mold under pressure. As a result, one or more key domes
302
of the keypad assembly
300
may become collapsed. Due to the pressures exerted within the mold during molding of the housing
304
, the subsequent depression
306
formed within the key dome
302
when it collapses becomes filled with resin, which sets and hardens, permanently holding the key dome
302
in the collapsed position. As a result, the keypad assembly
300
registers a continuous key press making the keypad assembly
300
, and the electronic device containing the keypad assembly
300
, unusable. Moreover, because the keypad assembly
300
is permanently encapsulated within the housing material of the electronic device, the electronic device typically cannot be repaired and must be discarded, resulting in unacceptable manufacturing waste when encapsulation methods are used.
Consequently, it is desirable to provide a keypad assembly for an electronic device such as a mobile telephone, a cordless telephone handset, a calculator, a hand-held computer, or the like, which utilizes touch detecting apparatus such as force sensors or touchpad assemblies instead of traditional key domes. The keypad assembly should be capable of encapsulation within the housing of the electronic device.
SUMMARY OF THE INVENTION
The present invention is directed to a keypad assembly that utilizes touch detecting apparatus such as force sensors or touchpad assemblies for registering key presses. The keypad assembly is suitable for use in electronic devices such as mobile telephones, cordless telephone handsets, calculators, hand-held computers, or the like. In exemplary embodiments, these electronic devices may have single-piece-molded housings wherein the keypad assembly is at least partially encapsulated within the housing. The present invention is also directed to methods for manufacturing encapsulated keypad assemblies and electronic devices employing an encapsulated keypad assembly.
According to a specific embodiment, the present invention provides a keypad assembly employing force sensors for registering key presses. The keypad assembly includes a substrate having one or more force sensors disposed thereon and an encapsulation layer molded onto the substrate over the force sensors. Each force sensor is suitable for sensing a force applied to a portion of the encapsulation layer over to the force sensor for registering a key press. Preferably, force registration by the force sensors is adjustable for canceling preload forces placed on the force sensor due to molding of the housing.
According to another specific embodiment, the present invention provides a keypad assembly employing a touch pad for registering key presses. The keypad assembly includes a plurality of electroluminescent (EL) sheets generally disposed or layered one over the other, each being capable of displaying a keypad when illuminated. A touchpad or touch screen is disposed over the electroluminescent sheets. Preferably, the touchpad is substantially transparent allowing the keypad of the illuminated electroluminescent sheet to be viewed by a user of the keypad assembly. The touchpad is suitable for detecting a touch or force applied over a key of the displayed keypad for registering a press of the key. The keypad assembly may be at least partially encapsulated, and may be employed by an electronic device such as a mobile telephone, cordless telephone handset, or the like.
According to another specific embodiment, the present invention provides a method for manufacturing an encapsulated keypad assembly. The method includes the steps of assembling a keypad utilizing a touch sensing assembly in accordance with the present invention, and overmolding an encapsulation layer onto the keypad so that the keypad is at least partially encapsulated within the encapsulation layer. The encapsulation layer may comprise a portion of the housing of the electronic device in which the keypad assembly is assembled. In one embodiment, the touch sensing assembly comprises a force sensor mounted to a substrate. In this embodiment, the method may further include the step of adjusting force registration by the force sensor for canceling preload forces placed on the force sensor by molding of the encapsulation layer. In another embodiment, the keypad assembly includes at least two electroluminescent (EL) sheets generally disposed or layered one over the other, each being capable of displaying a keypad when illuminated. A touchpad
Ward Isaac
Weselake Kenneth
Ghatt Dave A.
Siemens Communications Inc.
LandOfFree
Keypad assembly does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Keypad assembly, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Keypad assembly will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3304550