Coded data generation or conversion – Digital pattern reading type converter – Brush and contacts or conductive pattern
Reexamination Certificate
1999-08-10
2001-12-04
Jeanpierre, Peguy (Department: 2819)
Coded data generation or conversion
Digital pattern reading type converter
Brush and contacts or conductive pattern
C341S001000
Reexamination Certificate
active
06326905
ABSTRACT:
DESCRIPTION
1. Field of Invention
The invention relates to rotary electrical switches and to such switches having contacts coded to represent numeric values. More comprehensive aspects of the invention relate to security systems including addressable event detectors employing such switches to facilitate communications with microprocessors in control panels.
2. Background of the Invention
Security systems often include many event detectors in wired or wireless loops coupled to a local control panel. The loops might include fire and intrusion detectors, for example, that communicate with the panel when a covered event is detected. The panel controls the detectors and reports detected events both locally, through visual and audible alarms, and to a remote monitoring service.
Communications between the detectors and the panel often employ a unique address assigned to each detector when it is installed. The panel can address each detector individually by its unique address, and the detector includes its address in communications with the panel. In the latter case, the panel uses the address to identify the location of the detected event.
Many different types of address-setting switches are used in security detectors, including selectively positioned shunts and DIP (Dual Inline Package) switches. Most pertinent to the present invention are rotary coded switches set to represent multi-bit binary numbers. One example is sold as an electrical component adapted for mounting on a printed circuit board. It has contacts aligned in a row at different radial positions and a rotary cam with lobes positioned to selectively engage the contacts. Each contact represents one bit of a multi-bit binary number. Another example has a first set of contacts etched on a printed circuit board and another set of contacts mounted for rotation in engagement with the first contact set. Again, discrimination between the respective contacts is accomplished by radial displacement.
Although existing switches operate to accomplish their intended purpose, they suffer, for example, from complexity, relatively high cost, less than desired reliability or unduly large size. One problem involves numerous parts that add to the complexity of the switch, increasing manufacturing cost and reducing reliability. This problem is exaggerated by the number of parts that move relative to other parts or other components of the detector circuit. Another problem results from the radial displacement of the switch contacts, which requires a radial switch dimension sufficient to accommodate the contact displacement. This radial displacement undesirably increases the size of the switch. Although some problems are reduced by integrating the switch with the circuit board, others remain.
SUMMARY OF THE INVENTION
The invention provides a rotary switch that is small and reliable, having only a few parts that are inexpensive and easy to manufacture and assemble. It has particular utility with security devices where it provides unique addresses to facilitate communications between the devices and a local control panel.
According to one aspect of the invention, a switch having X rotary positions includes a plurality of first electrical contacts disposed at a common radius and a plurality of second electrical contacts mounted for rotation against the first electrical contacts at the common radius. The first electrical contacts include at least one contact representing a selectable logic level and other first contacts electrically isolated from the logic level contact(s). The second electrical contacts electrically couple the logic level contact(s) with a unique combination of the isolated contacts in each of the respective X positions. According to more specific features of this aspect, the first electrical contacts are disposed on a printed circuit board and the second electrical contacts are formed from a single piece of conductive material, such as a metal stamping. The first contacts define Y bits and the second contacts electrically connect the first contacts in X different positions to represent X unique binary numbers.
According to other aspects of the invention, a rotary switch is provided having multiple positions representing multi-bit binary numbers. The switch has a plurality of first electrical contacts fixed in a ring including logic level contacts and switching contacts. A plurality of second electrical contacts are mounted for rotation as a unit against the first contacts to define the multiple positions. The second contacts electrically couple unique combinations of the switching contacts to the logic level contacts in the respective positions. According to more specific features of this aspect, the first electrical contacts are defined by a circuit board, the second electrical contacts are defined by resilient conductive material and the resilient conductive material is compressed toward the circuit board. Still more specifically, each respective one of the switching contacts is unopposed by any respective other of the switching contacts.
More comprehensive aspects of the invention include a security product having a rotary switch as defined above, especially for communicating with a microprocessor of a local control panel. The first contacts include contacts electrically coupled to a microprocessor for selecting logic levels, and other contacts read by the microprocessor to establish addresses for communicating with the control panel.
These and other features and advantages of the invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
REFERENCES:
patent: 4400597 (1983-08-01), Bruder et al.
patent: 4728755 (1988-03-01), Fowler et al.
patent: 5008498 (1991-04-01), Yamazaki
patent: 5315077 (1994-05-01), Simon et al.
Detection Systems Inc.
Jean-Pierre Peguy
LandOfFree
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