Abstract: The present invention is an electronic thermostat having correction for the self heating due to the semiconductor switching device used to switch a temperature modifying apparatus on. This invention includes a semiconductor power switching device disposed on an upper portion of a vertically oriented circuit board, a first thermistor disposed on the circuit board at a lower portion thereof remote from the semiconductor power switching device, and a second thermistor disposed on the circuit board at a portion intermediate between the semiconductor power switching device and the first thermistor. A corrected ambient temperature is generated from the temperature indicated by the first thermistor and the difference in indicated temperature between the second thermistor and the first thermistor. The state of the semiconductor power switching device is then controlled based upon the relationship between the corrected temperature and a desired temperature.

Abstract: An electronic thermostat including a stored program of desired temperatures and predetermined maximum and minimum temperatures. The stored program of desired temperatures is selectable as either a program of heating temperatures or a program of cooling temperatures. When in the heating mode controlled by a program of desired heating temperatures, the cooling mode is entered and the air conditioner is energized if the actual temperature exceeds a predetermined temperature. The control temperature in this cooling mode has a predetermined relationship to the programmed temperature in the heating mode. Similarly, if the thermostat is in a cooling mode and the actual temperature falls below another predetermined temperature which is lower than the first predetermined temperature, then the thermostat enters the heating mode and energizes the furnace. The control temperature in this case bears a predetermined relationship to the programmed cooling temperature.

Abstract: The present invention is a control range display for an electronic thermostat. A plurality of individually actuable display segments are disposed in a line. Each of these display segments represents a particular temperature. The control range of the electronic thermostat is displayed by actuating the display segments representing the upper and lower preselected temperatures and all display segments therebetween. In the preferred embodiment each of these display segments is a liquid crystal display device. The preferred embodiment enables indication of the present temperature by actuation of a single display segment representing that temperature upon selection of a normal mode and an indication of the control temperature range by actuating display segments in the manner noted above upon selection of a program mode.

Abstract: The present invention is an apparatus and method for bidirectional alteration of a multivalue parameter from an initial value using a two-state manual input. In accordance with the present invention, the multivalue parameter is altered from its initial value in a first direction if the manual input is in a preselected state for less than a predetermined period of time. If the manual input is in the preselected state for a period of time longer than this first interval of time, then the multivalue parameter is altered from its initial value in the opposite direction. Additionally, if the manual input remains in the preselected state for additional periods of time, the value of the multivalue parameter is further altered in the opposite direction for each such additional interval. This invention is taught as useful in providing programs for programmable memory devices, in particular programmable thermostats.

Abstract: The present invention performs analog to digital conversion using the system clock of a microprocessor, the system clock being the clock which controls the rate of operation of the microprocessor. A varying analog signal is applied to the clock frequency control input of the microprocessor, thereby causing the clock frequency and the rate of operation of the microprocessor to vary in accordance with the varying analog signal. The clock is counted for a predetermined period of time. In the preferred embodiment this predetermined period of time is set by the 60 Hz AC power line. The counted contents at the end of this predetermined period of time is a digital representation of the varying analog signal. The microprocessor includes circuits for performing other operations at the rate set by the clock frequency. The other operations performed by the microprocessor must not be deleteriously affected by the varying rate of operation caused by the varying analog signal.

Abstract: A programmable electronic thermostat having selectable modes to control heating only, cooling only or both heating and cooling. This electronic thermostat enables an operator to program a series of desired temperatures over a repetitive heating or cooling cycle. The thermostat includes a clock that interrogates the stored program to generate a signal representative of the desired temperature for the present time which is compared with the measured temperature to generate control signals for a furnace or an air conditioner. The electronic thermostat may be placed in an automatic mode which controls both the furnace and the air conditioner. This automatic mode may be entered when a program of desired heating temperatures has been stored, whereupon the air conditioner is controlled based upon a cooling temperature having a predetermined relationship to the desired heating temperature. Similarly, this automatic mode may be invoked when only a program of desired cooling temperatures is stored.

Abstract: An electronic programmable thermostat for the control of a furnace or air conditioner is useful as a replacement for a conventional non-programmable thermostat and mounts on the non-programmable thermostat's wall plate to achieve support, electrical connection with the load and power supply, and the use of certain manual controls supported on the wall plate. The programmable thermostat employs a circular printed circuit board supporting its electronic components, which include a potentiometer for operator adjustment of desired temperature. A flat circular knob supported on the potentiometer shaft and an annular bezel cover the thermostat and allow access to the manual controls supported on the wall plate. The potentiometer and a temperature sensing thermistor control the frequency of a pulse generator which provides input to a counter.

Abstract: A programmable electronic thermostat for use in a building having a furnace and an air conditioning system adapted to generate energizing signals for the furnace and the air conditioner. An operator programs the thermostat with a series of desired temperatures over a repetitive heating or cooling cycle. During the winter, relatively high temperatures will typically be programmed during the period when the building is occupied and relatively low temperatures during unoccupied periods. The thermostat includes a clock that interrogates the program to generate the desired temperature for the present time which is compared to the measured temperature within the building to generate control signals for the furnace. In order to energize the air conditioning system during occasional periods of occurrence of high temperature, a control temperature is derived for the air conditioner.

Abstract: An electronic de-icing thermostat adapted to be connected to an air-cooling apparatus, such as an air conditioner, to control its state of operation. The thermostat includes means for generating a digital electrical signal representative of a desired temperature setpoint, means for measuring the ambient temperature of the thermostat and means for generating control signals for deenergizing the compressor in the air-cooling apparatus for a first preselected period of time whenever the compressor is determined to have run continuously for a second preselected period of time in order to inhibit the accumulation of ice on the cooling element of the air-cooling apparatus. The device preferably includes means for adaptively adjusting the length of the second and/or first preselected periods of time as a function of the change in the rate of change of the ambient temperature measured during the operation of the air-cooling apparatus.

Abstract: A programmable thermostat employing means for sensing the ambient temperature on the thermostat, a clock for generating digital electrical signals representative of real time, a programmable digital memory for retaining a schedule of times and temperature ranges for a particular repetitive time cycle, display means for indicating selected information including programming mode, time, and temperature conditions during the programming and operation of the device, and control means for interrogating the current temperature range in the times-temperatures schedule, determining whether the ambient temperature on the thermostat is within that range, and generating a control signal to the furnace or air conditioner when appropriate.

Abstract: A control system for an electrically energized humidifier used with a hot-air furnace including an electric time-delay circuit and control means for manually adjusting the time delay. Each time the thermostat for the system energizes the furnace the humidifier is energized for the predetermined time delay or until the furnace is de-energized, whichever occurs first. The time delay is manually adjusted so that it is longer than the energization cycle of the furnace in warm weather and shorter than the energization cycle of the furnace in cold weather. It is also manually adjusted so that in cold weather at the maximum energization cycle, the humifidier does not produce condensation within the building. The relative humidity of the conditioned air thus decreases proportionately to increases in the atmospheric temperature.

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.

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.

Abstract: An electric thermostat operative to be connected to a furnace or other temperature modifying apparatus to control its state of operation includes means for generating a desired temperature set-point signal and means for measuring ambient temperature at the thermostat. When the ambient temperature falls sufficiently below this set-point, the furnace is energized until the ambient temperature rises to a stored temperature level, also below the set-point. The system then monitors the peak ambient temperature reached during the following temperature overshoot resulting from the inertia of the furnace. The temperature differential between this limiting temperature obtained and the set-point is then added to the stored temperature value if the system did not obtain the set point temperature or substracted from the stored temperature value if the system exceeded the set-point value.

Abstract: An electronic thermostat operative to be connected to a furnace or other temperature modifying apparatus, to control its state of operation, includes means for generating a desired temperature set point signal and means for measuring ambient temperature on the thermostat. When the ambient temperature falls below the set point the furnace is energized for a predetermined period of time. The time of energization is increased or decreased by a small increment after each heating cycle depending upon magnitude of the temperature increase which occurred at the thermostat as a result of the heating cycle in order to adaptively achieve a predetermined temperature increase during the heating cycle and the thermal overshoot period which occurs following de-energization of the furnace.

Abstract: A control system for a humidifier, associated with a hot air furnace, that attains a high level of relative humidity without causing any condensation on the building interior by varying the level of operation of the humidifier as a function of the rate of heat loss from the building. Since the duty cycle of the furnace is a function of the rate of the heat loss, the system generates a digital signal related to the duty cycle and uses that signal to interrogate a digital memory storing a program of desired humidities for various duty cycles to output an instantaneous desired humidity signal which is compared with a measured humidity signal to develop an on/off control signal for the humidifier.

Abstract: An electronic thermostat operative to be connected to a furnace or other temperature modifying apparatus, to control its state of operation, includes means for generating a desired temperature set point signal and means for measuring ambient temperature on the thermostat. When the ambient temperature falls below the set point the furnace is energized for a predetermined period of time. The time of energization is increased or decreased by a small increment after each heating cycle depending upon magnitude of the temperature increase which occurred at the thermostat as a result of the heating cycle in order to adaptively achieve a predetermined temperature increase during the heating cycle and the thermal overshoot period which occurs following de-energization of the furnace.

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.

Abstract: A thermostat for generating control signals for a furnace, air conditioner, or the like, employs a constant frequency periodically alternating electrical source and an oscillator incorporating an element having a thermal-sensitive electrical characteristic so the oscillator frequency varies as a function of the ambient temperature. A comparator receives the two outputs and generates a signal representative of the ambient temperature. The stable output is also provided to dividing circuits to generate a signal representative of the time that is used to interrogate a digital memory storing a desired temperature-time program for the thermostat for a repetitive period, such as a week or month. The ambient temperature signal is compared with the desired temperature signal to generate an output conrol signal. A display provides a read-out of time and temperature and is used along with keyboard or the like in programming the memory.