Electrical resistors – Resistance value responsive to a condition – Force-actuated
Reexamination Certificate
2000-08-21
2001-03-13
Gellner, Michael L. (Department: 2832)
Electrical resistors
Resistance value responsive to a condition
Force-actuated
C338S099000, C338S071000, C338S114000, C200S0050EA, C200S00600C
Reexamination Certificate
active
06201468
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to sensors which translate the degree and direction of deflection of an input control of the sensor into electrical resistance signals which correlate to the degree and direction of deflection forces applied to the input control; and, more specifically, to an improved low cost deflection sensor consisting of a single component part, which may be manufactured in miniature size so that it may be utilized where space for such a deflection sensor is limited.
BACKGROUND OF THE INVENTION
Deflection sensors are utilized in a myriad of different applications. Typical applications of deflection sensors include joysticks, fluid level sensors, pressure sensors, scales, security sensors, position sensors, robotic feedback position and force sensors, and the like.
As an example of an application of known deflection sensors, various computer keyboards, video game controls, hand held remote controls and similar devices are known to incorporate deflection sensors for providing joystick pointing control, through which an input of speed and directional vectors is measured and transformed into electrical signals. In such applications the design of the deflection sensor used for joystick pointing control has been dictated by several considerations, including, the necessity to miniaturize the overall size of the design, the number and cost of component parts, and the ease or difficulty encountered in mass production and the associated cost of production. Such design constraints of prior deflection sensors used for joystick pointing controls resulted in limitations of variability of speed and direction, required an extensive amount of space, exceeded the pricing point of competing products or resulted in reduction in the useful life and durability of the deflection sensor.
Additional examples of applications of known deflection sensors include, fluid level senders, pressure senders, position senders and scales which utilize deflection sensors to measure mechanical displacement values and transform them into electrical signals. Often similar in design to the deflection sensors utilized for joystick pointing control, the design constraints of the known defection sensors of these devices has resulted in the same shortcomings as those associated with the known joystick pointing controls previously referred to.
One typical deflection sensor design and method provides one or more contacts which slide upon resistive or conductive regions to effect one or more resistive signals corresponding to the direction and/or degree of deflection. The shortcomings to this method of deflection sensing are that operational contact results in abrasion of the resistive or conductive regions, reducing the sensors useful life, and assembly requires many component parts, resulting in increased size and increased manufacturing cost. U.S. Pat. No. 4,864,272 to Cecchi et al, is representative of this type of design and method of a deflection sensor.
Another typical design and method of a deflection sensor provides a pivoting conductive element which makes contact upon a substrate with electrical traces or resistive regions, to provide one or more resistive signals corresponding to the direction and/or degree of deflection. A principle shortcoming to this method being that the resistive signal resolution and the ability to miniaturize the sensor are necessarily compromised by the need to avoid over-congestion of the electrical traces or resistive regions of the substrate. U.S. Pat. No. 5,376,913 to Pine et al, and U.S. Pat. No. 5,675,309 to DeVolpi are representative of this type of design and method of a deflection sensor.
Digital designs and methods have been employed in deflection sensors. By their very nature, these designs and methods are limited in the resolution of the signals provided to indicate speed and/or direction, and miniaturization results in further limitation of signal resolution capacity. U.S. Pat. No. 5,488,206 to Wu, and U.S. Pat. No. 4,896,003 to Hsieh are illustrative of digital deflection sensors.
A further design and method for deflection sensors utilizes the measurement of the change in resistance of a piece of resistive rubber material upon compression. In practice, a mechanical means is provided to transmit compression forces to the resistive rubber. Through compression, the measurable resistance of the rubber changes, which is measured at various contact points to provide signals of measurable resistance. A principle shortcoming to this method and design are that compression of the resistive rubber causes deterioration and wear and permanent changes in the resistance value of the resistive rubber. These changes and deterioration are further accelerated when rigid materials are utilized to compress the resistive rubber.
Accordingly, it is the object of the present invention to provide an improved analog deflection sensor which adapts itself well for use as a joystick pointing device, that occupies very little space, has broad speed and direction variability, consists of a single component part which lends itself to easy assembly and mass production for a small cost, with consistent quality and durability.
SUMMARY OF THE INVENTION
The objects of the present invention are attained by a deflection sensor which uses all resistive, or a combination of resistive and conductive contact elements. The contact elements are situated in parallel alignment to each other, are elastic, and may be made of various materials. A dielectric material that is also elastic is utilized to align and provide proper spacing of the contact elements in an undeflected position in the absence of external force.
In a first embodiment of the deflection sensor which can be used as a joystick pointing device, a central contact element of resistive rubber is surrounded by a number of, (typically four), peripheral contact elements of resistive rubber. The peripheral contact elements are positioned parallel to the central contact element at various angles, (usually in an x-y axis type of orientation). A dielectric spacer of elastic material is utilized to maintain the alignment and spacing of the central contact element and the peripheral contact elements in an undeflected position in the absence of external force.
In the undeflected position, gaps are maintained between the central contact element and the peripheral contact elements. In application, the central contact element and the peripheral contact elements are secured at one end and deflectional forces are applied at the other end. Application of a deflectional force causes the central contact element, the peripheral contact elements and the dielectric spacer to bend as a unit, and causes electrical contact to be established between the central contact element and one or more of the peripheral contact elements. As the area of electrical contact between the central contact element and each peripheral contact element corresponds to the direction and intensity of the deflectional force, and as the measured resistance between the central contact element and a peripheral contact element is a function of the area of electrical contact between them, one or more signals of measurable resistance corresponding to the direction and intensity of the deflectional force is provided. These signals of measurable resistance are readily translated into speed and directional vectors by analog to digital or RC timing circuitry, with resolution limited only by the analog to digital or RC timing circuitry employed.
An alternate embodiment of the deflection sensor of the current invention provides for applications where a deflectional sensor is utilized for measurement upon a single axis. In this alternate embodiment of the deflection sensor, a central contact element of resistive rubber is surrounded by two peripheral contact elements of resistive rubber. The peripheral contact elements are positioned parallel to the central contact element in a linear arrangement. A dielectric spacer of elastic material is utilized to maintain the alignme
Gellner Michael L.
Lee Kyung S.
Quinn Cornelius P.
Quinn William J.
Quinn & Quinn P.C.
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