Electronic thermostat with repetitive operation cycle

• US 4,531,064 A
• Filed: 02/13/1984
• Issued: 07/23/1985
• Est. Priority Date: 05/27/1980
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Michael R. Levine
• Inventors: Levine, Michael R.
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): DeBoer, Todd E.
• Application Number:
  US06/579,409
• Time in Patent Office: 526 Days
• Field of Search: 307/66, 307/200 A, 307/219, 377/32, 331/66, 331/70, 340/870.17, 340/501, 340/588, 340/589
• US Class Current: 307/66
• CPC Class Codes: F23N 5/203 using electronic means
• CPC Class Codes: G05D 23/1904 variable in time
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor

Abstract

An electronic multiple-setback thermostat for residential and commercial use includes an internal clock having a week-long cycle. The thermostat is programmed by the operator, usually manually actuable input devices, to control the furnace/air conditioning system to achieve a schedule of temperatures over the weekly period by simply inputting the temperature desired to be attained at the time of entry. Each temperature entry may be programmed to reoccur on a daily basis or to modify the program on a once-a-week basis. The thermostat employs an internal clock which controls memory addresses so that each memory location is representative of a short time period during the weekly cycle. A desired temperature signal is entered in a memory location determined by the clock state at the time of entry and is read out to the control system each time that time state reoccurs. The external temperature sensor employs a thermistor controlled oscillator that is used as the system clock source during failures of the primary power source.

Claims

1. An apparatus that generates clock pulses in a microprocessor-controlled electronic thermostat, normally powered from an A.C. line voltage, even during line voltage outages, the apparatus comprising:

a backup battery supply;

a variable frequency oscillator;

means driving the oscillator at a frequency proportional to the ambient temperature;

a resettable counter counting the oscillations of the oscillator and capable of generating an overflow signal when the count increases past the limits of the counter;

a bi-state switch means supplying battery power to the thermostat when the switch means is in its first state and removing battery power from the thermostat when the switch means is in its second state, the switch means being placed in its first state in response to an overflow of the counter;

means detecting zero crossings of the A.C. line voltage and, upon detection of a zero crossing, causing the storage of the count presently in the counter, resetting the counter, placing the switch means in its second state, and generating a clock pulse; and

a comparator, operative when the switch means is in its first state, comparing the stored count with the count presently in the counter and, when the two are equal, generating a clock pulse.