Electricity: electrical systems and devices – Electrostatic capacitors – Variable
Reexamination Certificate
2002-03-06
2002-12-24
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Variable
C361S298200
Reexamination Certificate
active
06498712
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates in general to variable electronic components, and more particularly, to a variable trimmed capacitor having a design that reduces manufacturing time and cost while providing a high level of quality.
Capacitors are critical components used in a vast array of electronic devices, from simple circuit boards to entire computer systems. Capacitors have two main types, fixed and variable. A fixed capacitor has a pre-defined capacitance that is fixed during manufacturing. Variable or trimmed capacitors do not have their capacitance fixed during manufacturing. Instead, these capacitors are designed so that they afford a range of capacitance values. Adjusting along this range allows a user, for example, to fine-tune a circuit. Thus, variable capacitors are often employed in transmitter and receiver circuitry. Variable capacitors are known from U.S. Pat. Nos. 5,229,911; 5,155,654; 4,876,627; 4,764,843; and 4,575,779, all assigned to the assignee of this application, the disclosures of which are incorporated herein by reference.
Variable capacitors come in many different designs. One method of varying capacitance is to interleave several variable electrodes among fixed electrodes. See U.S. Pat. Nos. 4,002,957; 3,624,469; and Re. 30,406. Adjusting the position of the variable electrodes relative to the fixed electrodes increases or decreases the capacitance. One drawback to this kind of variable capacitor is the number of electrodes. Multiple fixed and variable electrodes necessitate a housing large enough to accommodate them. This may make these devices unsuitable for many small-scale applications. And if the fixed and variable electrodes are not carefully situated, or if the structure is not rugged enough, the capacitor may not operate properly.
Other drawbacks to variable capacitors are that the outer housing is often formed of multiple parts, and the entire structure is held together with a combination of screws, clips, soldering and other connection mechanisms. As components are added, manufacturing time and expense rise. Likewise, certain processes such as soldering or welding sections of the capacitor together also increase the cost and time of manufacturing. Furthermore, each additional step in the manufacturing process increases the chance for error, so the percentage of device failures may rise. In turn, this also drives up the cost of manufacturing.
Accordingly, there is a need for improvements in variable capacitors, and in particular, to provide a simple variable capacitor design having a minimum number of components, and for the variable capacitor to be quickly and easily assembled at a low cost.
SUMMARY OF THE INVENTION
In one embodiment of the present invention, a variable electronic component is provided. The variable electronic component comprises a dielectric housing, a conductive stator and an actuator assembly. The dielectric housing includes a hollow tubular body having an open end. The conductive stator surrounds a portion of the dielectric housing. The actuator assembly is secured within the dielectric housing. The actuator assembly includes a conductive body moveable within the hollow tubular body. The conductive body is in operative relationship with the conductive stator upon operation of the actuator assembly. The actuator assembly also has at least one projection adapted to secure the actuator assembly within the hollow tubular body at the open end.
In another embodiment of the present invention, the at least one projection includes a plurality of teeth. Preferably, the plurality of teeth circumscribe an outer surface of the actuator assembly, whereby the plurality of teeth grab into an inner surface of the hollow tubular body at the open end.
In another embodiment of the present invention, the at least one projection includes an annular ring. The annular ring surrounds an outer surface of the actuator assembly, whereby the annular ring grabs into an inner surface of the open end.
In another embodiment of the present invention, the actuator assembly is friction fit into the dielectric housing. The at least one projection digs into an inner surface of the dielectric housing.
In another embodiment of the present invention, the dielectric housing, conductive stator and the actuator assembly form a capacitor. Adjusting the actuator assembly in operative relation to the conductive stator varies a capacitance of the capacitor.
In another embodiment of the present invention, the dielectric housing includes a closed end opposing the open end. The conductive stator surrounds the portion of the dielectric housing having the closed end.
In another embodiment of the present invention, the hollow tubular body includes an outer surface. The hollow tubular body is at least partly exposed along a portion of the outer surface to the surrounding environment.
In another embodiment of the present invention, the hollow tubular body further includes an opposing closed end opposite the open end. The hollow tubular body includes an outer protrusion between the open end and the opposing closed end. The conductive stator has a portion that is attached about the outer protrusion.
In another embodiment of the present invention, the variable electronic component further includes a ring. The ring surrounds a portion of the hollow tubular body about the open end. The ring prevents the hollow tubular body from disengaging from the at least one projection.
In yet another embodiment of the present invention, a variable capacitor is provided. The variable capacitor comprises a housing of dielectric material, a plug, a metal body, a stator and an actuator. The housing of dielectric material has a closed end and an open end having an inner surface. The closed end and the open end form a bore therebetween. The plug has an outer surface and an inner opening. The outer surface includes at least one projection embedded into the inner surface, thereby securing the plug within the bore of the housing adjacent to the open end of the housing. The metal body is moveably received within the bore of the housing between the closed end and the plug. The stator surrounds an outer portion of the closed end of the housing. The actuator is received within the inner opening of the plug and is attached to the metal body. The actuator is operable to axially move the metal body within the bore of the housing in operative relationship to the stator, whereby the capacitance of the variable capacitor is altered.
In another embodiment of the present invention, the at least one projection includes a plurality of teeth. Preferably, the plurality of teeth circumscribes the outer surface of the plug, whereby the plurality of teeth digs into the inner surface of the bore.
In another embodiment of the present invention, the at least one projection includes at least one annular ring. The at least one annular ring digs into the inner surface of the bore.
In another embodiment of the present invention, the plug is press fit into the housing. Preferably, the dielectric material is polytetrafluoroethylene.
In another embodiment of the present invention, the actuator is threaded. The inner opening of the plug is reciprocally threaded to engage the actuator.
In another embodiment, the variable capacitor further includes a ring surrounding a portion of the open end. The ring prevents the inner surface from disengaging from the at least one projection.
In yet another embodiment of the present invention, a variable electronic component is provided. The variable electronic component comprises a dielectric housing, a conductive stator and an actuator assembly. The dielectric housing includes a hollow tubular body having an open end and an opposing end. The hollow tubular body includes an outer surface whereby the hollow tubular body is partly exposed along a portion of the outer surface to the surrounding environment. The conductive stator surrounds a portion of the dielectric housing at the opposing end. The actuator assembly includes a conductive body. The conductive body is move
Dinkins Anthony
Lerner David Littenberg Krumholz & Mentlik LLP
Voltronics Corporation
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