Abstract An energy conserving thermostatic control system having digitally implemented control functions for use with a heating and/or air conditioning system is disclosed. The digital thermostat includes an LCD data display for simultaneously displaying present time and ambient temperature. Slide switches are provided for setting and indicating set point information such as day temperature, night temperature, night-to-day transition time, and day-to-night transition time. The switch contacts of each slide switch are multiplexed to the display driver conductors for conveying time and temperature set point data during time and temperature scan intervals which alternate with a display interval. Strobe signals which are applied to the driver conductors are counted during the alternate scan intervals for selecting a day temperature different from a night temperature, for selecting the times which divide night from day and for providing set-back to night temperature during a predetermined time of the day. A day-skipper circuit inhibits set-back on selected days. A power divider circuit is provided which permits wire-for-wire substitution of the digital thermostat for a conventional electro-mechanical thermostat.
In an automatic thermostat of the type having a programmable switch circuit for cycling heat transfer apparatus on and off, the improvement comprising: a system mode interrogator for generating a signal representative of the selected system mode; a temperature comparator circuit for performing the comparative relation operations (T A -T SET ) or (T SET -T A ) and for generating a turn-on command signal when either one of the following comparative relations is satisfied: T A -T SET ≧K 1 in response to a mode signal indicating the cooling mode, T SET -T A ≧K 2 in response to a mode signal indicating the heating mode; a timing circuit responsively coupled to the programmable switch and to the temperature comparator for enabling the transmission of the turn-on command signal after the elapse of a predetermined minimum-off interval following the generation of the turn-on command signal; and, a temperature differential control unit coupled to the temperature comparator to carry out the following operations in response to the presence of the turn-on command signal and to the enabling condition of the minimum-off timer: T A -T SET ≧ΔT 1 , in response to a mode signal indicating the heating mode, and T SET -T A ≧ΔT 2 , in response to a mode signal indicating the cooling mode, the turn-on command signal being terminated when either of the latter comparative relations are satisfied, wherein K 1 , K 2 , ΔT 1 , and ΔT 2 are arbitrary temperature bias values, and T A =ambient temperature, T SET =set point temperature.
Claim 2
Dependent Claim
260 words
In an automatic thermostat of the type having a programmable switch circuit for cycling heat transfer apparatus on and off, the improvement comprising: a system mode interrogator for generating a signal representative of the selected system mode; a temperature comparator circuit for performing the comparative relation operations (T A -T SET ) or (T SET -T A ) and for generating a turn-on command signal when either one of the following comparative relations is satisfied: T A -T SET ≧K 1 in response to a mode signal indicating the cooling mode, T SET -T A ≧K 2 in response to a mode signal indicating the heating mode; a timing circuit responsively coupled to the programmable switch and to the temperature comparator for enabling the transmission of the turn-on command signal after the elapse of a predetermined minimum-off interval following the generation of the turn-on command signal; and, a temperature differential control unit coupled to the temperature comparator to carry out the following operations in response to the presence of the turn-on command signal and to the enabling condition of the minimum-off timer: T A -T SET ≧ΔT 1 , in response to a mode signal indicating the heating mode, and T SET -T A ≧ΔT 2 , in response to a mode signal indicating the cooling mode, the turn-on command signal being terminated when either of the latter comparative relations are satisfied, wherein K 1 , K 2 , ΔT 1 , and ΔT 2 are arbitrary temperature bias values, and T A =ambient temperature, T SET =set point temperature.