Pressure sensitive direction switches

Details Pressure sensitive direction switches Pressure sensitive direction switches

2000-04-20

2001-11-06

Donovan, Lincoln (Department: 2832)

Electrical resistors

Mechanically variable

Movable contact electrically adjustable over length of...

C338S128000, C338S071000, C200S0050EA

Reexamination Certificate

active

06313731

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to input devices and more particularly to direction switches.
BACKGROUND OF THE INVENTION
As a general rule, portable devices, such as radiotelephones and computers, continue to shrink in size and to be configured in small compact packages (i.e., “pocket” sized radiotelephones). Recent radiotelephones have incorporated a variety of new features ranging from optional communication services, including Internet access, through videogames. As a result, menu structures of such devices typically become more complex. Such communication device applications, as well as devices such as laptop computers and portable games, may utilize multi-directional switches, such as 4-way switches. A select switch may be provided apart from, or integrated with, the pressure sensitive switch.
Various known approaches to pointing devices include a joystick, a mouse and a trackball. A mouse and a trackball typically use electromechanical or optical systems to convert a rotational motion of a ball to a linear motion of a cursor. Joysticks typically include an array of digital contact switches that detect when the joystick is moved in a particular direction. Various pointing devices detect both direction and pressure by sensing the magnitude and direction of a force applied to the pointing device. Examples of pressure sensitive pointing devices are described in U.S. Pat. Nos. 5,231,386 (“the '386 patent”) and U.S. Pat. No. 5,828,363 (“the '363 patent”).
The '386 patent is directed to a keyswitch-integrated pointing assembly in which a plurality of substantially planar force sensing elements are disposed on a planar surface adjacent a keyswitch on a keyboard. The device thus combines a keyswitch with force sensing resistor elements. A rubber dome sheet extends between the actuator element and the force sensing elements to disperse applied forces smoothly. The forcing sensing resistors are pre-loaded to bias the elements into a substantially linear operating region when no force is applied to address problems with stability associated with non-linear operating ranges of force sensing resistors.
The '363 patent is directed to another type of force-sensing pointing device utilizing force sensing resistors to detect the magnitude and position of an applied force. A connector, such as an elastomeric adhesive, maintains a force transfer member in contact with the force sensing resistors. A related product is available from Interlink Electronics of Camarillo, Calif. as described in the associated High-Precision MicroJoystick Integration Guide. This product is described as being suited to computer-cursor control and as providing both a click (select switch) function and cursor speed control responsive to the amount of an applied pressure.
SUMMARY OF THE INVENTION
The present invention provides pressure sensitive switching devices which may facilitate assembly and provide higher tolerance for variation in alignment of components while still providing for pressure sensitive direction detection. The devices of the present invention may be particularly advantageous when integrated into devices, such as cellular radiotelephones, to provide a user interface to facilitate user navigation through increasingly complex menu structures. In various embodiments, the present invention may detect pressure in addition to two and, preferably, at least four directions. In particular embodiments, the devices of the present invention may provide switching devices having a plurality of trace grid areas located, for example, on a printed circuit board and actuated responsive to pressure applied by a user through a poly-dome layer where increased pressure results in contact with a greater number of the traces in respective grids. Alternative embodiments include trace patterns which are substantially circumferentially arranged in patterns configured to detect user input. A select switch is included in various embodiments of the present invention.
In embodiments of the present invention, pressure sensitive direction devices are provided. A first member includes a plurality of contact regions, each of the contact regions including trace lines, the trace lines being formed from one of a conductive and a resistive material. A second member is positioned adjacent the first member, the second member including a plurality of deformable switch regions. The plurality of deformable switch regions are positioned adjacent the plurality of contact regions and have an inner surface on a side adjacent the first member. The deformable switch regions include a connection layer on the inner surface thereof. An actuator has contact regions positioned adjacent an outer surface of the deformable switch regions. The contact regions of the actuator deform the switch regions responsive to pressure on the actuator in the vicinity of the contact regions of the actuator to compress at least one of the deformable regions so as to bring the connection layer into contact with a number of trace lines of the contact regions of the first member, the number of trace lines being proportionate to the pressure on the actuator.
In other embodiments of the present invention, the connection layer is formed from the other of the conductive and the resistive material so that one layer is conductive and the other is resistive. Preferably, the first member includes at least three contact regions and the contact regions are positioned in spatially displaced locations on the first member. The trace lines may include a first grid of trace lines electrically coupled to a first output and a second grid of trace lines electrically coupled to a second output. The deformable switch regions may be spatially displaced domes formed in the second member. The domes may be concave when viewed with reference to the inner surface of the second member and the contact regions of the actuator may be convex when viewed with reference to the inner layer of the actuator with the convex contact regions substantially aligned with the domes. A keycap layer may be positioned adjacent an outer layer of the actuator to provide a user contact surface. The first member may be a printed circuit board and the second member may be a poly-dome layer. The resistive material may be a resistive ink and the actuator may be formed of a deformable non-conductive material.
In further embodiments of the present invention, the pressure sensitive direction device includes a select switch positioned in the pressure sensitive direction device. The select switch may include a switch contact region associated with the first member and electrically isolated from the plurality of contact regions and a conductive dome positioned adjacent the switch contact region. A select actuator may be positioned above the conductive dome and have a first position when unloaded not placing the conductive dome in contact with the switch contact region and a second position when loaded placing the conductive dome in contact with the switch contact region. The conductive dome may be a metal dome and the second member may include an aperture configured to allow the metal dome to pass through the second member. Alternatively, the second member may be a unitary member formed from a non-conductive material and including the conductive dome and the plurality of domes and the conductive dome may include a conductive material layer on the inner surface of the conductive dome. The switch contact region may be positioned between the plurality of contact regions and the conductive dome may be positioned between the plurality of domes.
In other embodiments of the present invention, the trace lines in each of the plurality of contact regions are 3 or more separate trace lines and the trace lines and the connection layer comprise a conductive material. The separate trace lines are positioned adjacent each other so as to provide a digital signal output having an increasing number of the separate trace lines being selected by contact with the connection layer responsive to increa

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