Electricity: battery or capacitor charging or discharging – Battery or cell discharging – Regulated discharging
Reexamination Certificate
1999-10-29
2001-01-09
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
Regulated discharging
C307S117000
Reexamination Certificate
active
06172484
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of controlling a high-current load, and, more particularly, to a method of controlling a high-current load dependent upon at least one predetermined condition.
2. Description of the Related Art
Power can be applied to a load upon the presence of a predetermined condition using a so-called “two wire” connection. In a two wire control system, a same power source supplies power to both the load and a control circuit which includes a sensor for determining the presence of the predetermined condition. Power is cyclically switched between the load and the control circuitry via a switch controlled by the control circuitry. In order to maintain operation of the sensor and other electronics while power is being diverted to the load, the control circuitry includes an electrical energy storage device which stores enough electrical energy to maintain operation of the sensor and the associated electronics while power is being diverted to the load. In order to ensure that the voltage level supplied by the storage circuit does not drop below a minimum level required for operation of the sensor and the electronics, the voltage output by the storage circuit is continuously monitored. When this storage circuit voltage falls below a predetermined level, power is diverted back to the control circuitry from the load in order to replenish the storage circuit. When the storage circuit voltage has reached a predetermined target voltage, the power source can again be connected to the load while the electrical energy stored in the storage circuit is used to operate the control circuitry.
A problem is that monitoring the voltage output from the storage circuit adds to the complexity and expense of the control circuitry. In cases where the storage circuit output voltage declines with time in a repeatable and predictable manner, the monitoring of this storage circuit output voltage represents a waste of resources. Also, if the circuitry which monitors the storage circuit output voltage is damaged or otherwise inoperable, it is possible for either the load or the control circuitry to lose power.
What is needed in the art is a method of maintaining a minimum level of electrical energy within a storage circuit while a power source is being diverted to a load, such that monitoring of the voltage output of the storage circuit is not required.
SUMMARY OF THE INVENTION
The present invention provides a method of cyclically replenishing the electrical energy stored within a storage circuit at a fixed frequency so that the storage circuit can maintain operation of sensor circuitry while power is being diverted to a load.
The invention comprises, in one form thereof, a method of controlling a load dependent upon at least one predetermined condition. The method includes determining a presence of the at least one predetermined condition with at least one sensor. A signal is transmitted from the at least one sensor to an electrical processor dependent upon whether the at least one predetermined condition is present. A switch device is controlled with the electrical processor dependent upon the signal from the at least one sensor. The switch device has a first state in which the switch device connects a power source to the load, and a second state in which the switch device connects the power source to the at least one sensor, to the electrical processor and to a rechargeable energy storage device. If the predetermined condition is not present, the switch device is maintained in the second state. If the predetermined condition is present, the switch device is cyclically switched between the first state and the second state. The cyclical switching occurs at at least one predetermined frequency. The rechargeable energy storage device temporarily supplies power to each of the at least one sensor and the electrical processor when the switch device is in the first state. The power source recharges the rechargeable energy storage device when the switch device is in the second state.
An advantage of the present invention is that monitoring of the voltage output of a storage circuit, and the electronic circuitry required for performing such monitoring, are not necessary, thereby decreasing the cost and complexity of the control circuitry.
Another advantage is that the reliability of the control circuitry is improved since the function of controlling the switching of power to the storage circuit is performed within an integrated circuit.
REFERENCES:
patent: 4336463 (1982-06-01), Beeghly
patent: 4365167 (1982-12-01), Weimer et al.
patent: 5023529 (1991-06-01), Tennant
patent: 5306955 (1994-04-01), Fryer
patent: 5523547 (1996-06-01), Miller
patent: 5682748 (1997-11-01), DeVilbiss et al.
patent: 5825233 (1998-10-01), Lamarche
patent: 5889466 (1999-03-01), Ferguson
MSX, Inc.
Taylor & Aust P.C.
Tibbits Pia
Wong Peter S.
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