Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-11-08
2001-06-26
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S319000
Reexamination Certificate
active
06252336
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to portable communication devices such as pagers and cellular telephones and more particularly to the use of a piezoelectric device which operates primarily as a battery charger for the communication device, but which can also be switched to act as a silent or vibration alarm to alert the user of an incoming call or page.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
The use of pagers and cellular telephones has increased at an almost explosive rate over the last decade. At the same time, the using public continues to demand that the pagers and cellular telephones be smaller and less obtrusive while at the same time have a longer and longer service time before the batteries are exhausted. The miniaturization of such devices has been largely successful. However, one of the physically largest and heaviest components has always been and continues to be the battery that powers the device. Thus, it is seen that the demands for both miniaturization and longer service time are in conflict and present an engineering challenge.
In the past, these conflicting demands had been partially solved by significantly increasing the efficiency of the battery to allow for longer use with smaller batteries. In addition, miniaturization of the communication device circuitry components has also helped solve the problem. However, circuit components are now very small and unfortunately further miniaturization may help somewhat in power consumption, but the actual weight and size of most of the components are so small that further reduction could be of little benefit. There are a few components, such as for example the housing or case of the device and the keypads used for dialing in a cellular telephone where further size reduction is extremely difficult since if the keys are not spaced sufficiently apart from each other it becomes difficult to select a single key. One component used by both pagers and cellular telephones which uses a significant amount of energy, is expensive, and rather large is the silent or vibration alarm. Typically, a small electrical motor is used to drive or rotate an unbalanced wheel to cause vibration to provide the silent alarm. These motors simply cannot be made much smaller and still drive a large enough vibration device to be useful. Further, in addition to being a relatively expensive component of the communication device, when actually operating they use a significant amount of the available battery power.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide methods and apparatus to allow further reduction of size and weight of a battery used in portable devices.
It is another object of the present invention to provide an inexpensive mechanism to provide vibration for a silent alarm.
It is still a further object of the present invention to provide a silent alarm mechanism which has a low overall resulting power use.
These and other objects are achieved by the piezoelectric device of this invention which selectively provides either vibration to the device or generates current responsive to movement as the device is carried or moved. The apparatus comprises an elongated support beam which extends along a first axis between first and second ends. The elongated support beam may be made of an electrically conductive material, or alternately may be made of a non-conductive material such as fibreglass and have a conductive layer or conductive portion. The elongated support beam is flexible and resilient along a second axis which second axis is substantially perpendicular to or across said first axis of the elongated support beam. A weight member is attached to the elongated support beam so as to cause flexure of the elongated support beam in response to movement of the communication device. A piezoelectric device having a first side (positive) and a second side (negative) is mounted to the conductive portion of the elongated support beam. A first conductor is connected so as to be an electrical contact with one side (negative) of the piezoelectric device and a second conductor is electrically connected to the other side of the piezoelectric device. A rectifier is provided which has an input and an output, and is connected such that the first and second conductors are electrically connected to the input of the rectifier and a selected load is connected to the output of the rectifier such that flexure of the elongated support beam causes distortion of the piezoelectric device thereby creating a current flow through the first and second conductors and then through the rectifying device to the selected load and battery. In a preferred embodiment, the piezoelectric device of this invention also further comprises an AC power source such as a DC to AC convertor and a switch connected between at least one of the first and second conductors and the rectifying device. The switch is also connected to the AC power source. The switch operates to selectively connect only one of the rectifying devices or the AC power source at a time to the first and second conductors. Thus, AC power may be provided to the piezoelectric device when the rectifying device is disconnected such that the piezoelectric device will continually be distorted and relaxed in response to the electrical current thereby causing a bending movement of the elongated support member and vibration of the device. It is this resulting vibration that then acts as a silent alarm for communication devices according to the present invention.
REFERENCES:
patent: 3093760 (1963-06-01), Tarasevich
patent: 3456134 (1969-07-01), Ko
patent: 4565940 (1986-01-01), Hubbard
patent: 5552656 (1996-09-01), Taylor
patent: 5621264 (1997-04-01), Epstein et al.
patent: 5703295 (1997-12-01), Ishida et al.
patent: 5751091 (1998-05-01), Takahashi et al.
patent: 2 095 053 (1982-09-01), None
patent: 44-26339 (1969-11-01), None
CTS Corporation
Dougherty Thomas M.
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