Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-11-26
2001-10-30
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S317000, C310S318000, C310S316010
Reexamination Certificate
active
06310428
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a piezoelectric switch and in particular to a piezoelectric switch having a circuit with a piezoelectric element incorporated in the switch housing which provides a pulse output, and an oscillating signal to the piezoelectric element for producing audible feedback when the piezoelectric element is activated by mechanical stress.
2. DESCRIPTION OF RELATED ART
Piezoelectric switches in the prior art have not incorporated an audible feedback using a piezoelectric element within the switch housing for detection by an operator activating the switch. If such a switch did exist, it could be used in current piezoelectric switch applications which do not have tactile or audio feedback.
The piezoelectric switch produces a momentary pulse; it is an all-electronic switch having no contact arcing or bounce and no movable parts or mechanical wear. Such a switch is a normally-open momentary, single pole, single throw (SPST).
In U.S. Pat. No. 4,028,502, issued Jun. 7, 1997 to Moricca et al., and assigned to Inventive Industries, Inc., an apparatus is described for providing auditory and tactile recognition of a light signal associated with a line-selector pushbutton of a multi-line telephone instrument. A photo cell senses a light signal and an oscillator generates a sine wave voltage which is amplified and applied to excite a piezoelectric crystal into vibration in response to activation of the photo cell. An auxiliary pushbutton is disposed in alignment with the line selector pushbutton so that manual depression of the auxiliary pushbutton actuates the line selector pushbutton. Vibration of the crystal in response to the light signal acts upon an auxiliary pushbutton to import the vibration thereto so that the presence of the light signal is sensed by a blind person by vibration of the auxiliary pushbutton.
In U.S. Pat. No. 4,430,595, issued Feb. 7, 1984 to Nakasone et al. and assigned to Toko Kabushiki Kaisha of Japan, a piezoelectric pushbutton switch is described comprising a housing with terminals embodied in four corners, a printed circuit board, a disk-shaped piezoelectric plate polarized in the direction of thickness and having its upper surface bonded to a conductive plate, a domed-shaped metal spring placed on the conductive plate, and a plunger placed on the metal spring 8. A cover has a through-hole into which the plunger is inserted. When the spring is bent, the operator can feel a clicking motion through the plunger and the finger. The piezoelectric plate floats free of the housing by being supported by a protruding piece on the flexible printed circuit board.
In U.S. Pat. No. 4,642,433, issued Feb. 10, 1987, to Taneo Murata, and assigned to Alps Electric Company, Ltd. of Japan a pushbutton switch with aural confirmation of operation is described. The switch used in a keyboard gives a tactile feel to the finger of the operator like a clicking and at the same time produces a clicking sound. The switch comprises a casing, a membrane switching device in the casing, a stem, a contact spring and a leaf spring which produces a clicking sound.
In U.S. Pat. No. 5,636,729, issued Jun. 10, 1997 to Richard Wiciel, a piezoelectric switch with a lighted push-button is described. The switch comprises a light-transmissive member having a first surface accessible to a tactile input and a second surface opposite the first surface, a case for mounting the member, a piezoelectric crystal mounted to the case and having a contact area, a light source disposed in the case, a spacer for transmitting the tactile input to the crystal causing the crystal to provide an electrical response to the tactile input to an electronic circuit.
SUMMARY OF THE INVENTION
Accordingly, it is therefore an object of this invention to provide a user of a piezoelectric pushbutton switch with audible feedback.
It is another object of the invention to use a piezoelectric element both as a switch and the source of audible sound in the same circuit.
It is a further object of this invention to minimize the circuit components so that a printed circuit board can fit within the piezoelectric switch housing.
It is yet another object of this invention to provide a piezoelectric switch comprising audible feedback which can easily replace a piezoelectric switch without audible feedback.
These and other objects are further accomplished by a piezoelectric pushbutton switch having audible feedback comprising a housing for enclosing components of the switch, a piezoelectric element attached to an inner top surface of the housing wherein applying pressure on the top of the housing causes the piezoelectric element to generate an electrical signal, a circuit board electrically connected to the piezoelectric element, for receiving the electrical signal, and the circuit board comprises circuit means for enabling the piezoelectric switch to generate an output signal having a predetermined pulse width and for enabling the piezoelectric element to provide the audible feedback. The piezoelectric element comprises electrical leads for providing electrical connection to the circuit means. The circuit means connected to the piezoelectric element comprises means for providing electrical connections outside of the switch. The housing comprises a cap for closing an open end of the switch, the camp comprises an opening for feeding electrical connections outside of the switch. The sound produced by the piezoelectric element comprises a buzzing. The enabling means comprises an oscillator circuit coupled to the piezoelectric element for producing the audible feedback. The housing comprises an epoxy for securing the components of the switch.
The objects are further accomplished by a piezoelectric switch comprising a piezoelectric element, means for sensing an electrical signal output from the piezoelectric element when activated, means connected to the electrical signal output of the sensing means for generating a pulse having a predetermined pulse width, and means connected to an output of the pulse generating means for generating an oscillating signal, the oscillating signal being coupled to the piezoelectric element for producing an audible feedback. The piezoelectric element output sensing means comprises a switch sensor circuit. The pulse generating means comprises a one-shot circuit.
The objects are further accomplished by a method of providing a piezoelectric pushbutton switch having audible feedback comprising the steps of, providing a housing for enclosing components of the switch attaching a piezoelectric element to an inner top surface of the housing wherein applying pressure on the top of the housing causes the piezoelectric element to switch and generate an electrical signal, providing a circuit board in the housing electrically connected to the piezoelectric element for receiving the electrical signal, generating an output signal having a predetermined pulse width from circuit means on the circuit board receiving the electrical signal, and generating an oscillating signal within the circuit means, the oscillating signal being connected to the piezoelectric element for producing the audible feedback. The step of attaching the piezoelectric element to an inner top surface of the housing comprises the step of providing electrical leads for connection to the circuit board. The step of providing a circuit board in the housing comprises the step of providing electrical leads extending from the circuit board outside of the housing. The step of providing a housing for enclosing components of the switch comprises the steps of adding an epoxy in the housing and a cap for closing an open end of the housing. The step of providing the cap comprises the step of including an opening in the cap for feeding electrical connections outside of the housing.
The objects are further accomplished by a method of providing a piezoelectric switch having audible feedback comprising the steps of providing a piezoelectric element in the switch, sensing an output of the piezoelectric element wh
Domzalski Frank M.
Pulli Hannu H.
ITT Manufacturing Enterprises Inc.
Medley Peter
Pearson & Pearson LLP
Ramirez Nestor
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