Abstract: A control device for energization of a load employs a bidirection triggerable solid state switching device connected in series with an alternating current power source and the load. In order to prevent the passage of excessive, potentially destructive currents through the switch if the load is shorted out, the microprocessor which controls the energization of the switch senses the time required for the voltage across the switch to attain a predetermined value. If the load is shorted the potential difference across the switch increases and attains the predetermined value a shorter time after zero-crossing of the alternating current. When this occurs more than a predetermined number of consecutive times, the generation of triggering pulses for the solid state switch is inhibited for a predetermined time. In the preferred embodiment the control device is a thermostat for controlling a temperature modifying load such as a furnace or air conditioner.

Abstract: An electronic thermostat includes selectable multiple predetermined temperature programs of desired temperatures over a repetitive time cycle. A manually operable temperature program selector enables recall of a desired temperature for a particular time from a temperature program memory in accordance with the selected predetermined temperature program. This desired temperature is compared to the ambient temperature in order to generate control signals for a temperature modifying device. In the preferred embodiment, the multiple temperature programs each consist of digital signals indicative of either a normal temperature or a set-back temperature. A separate operator actuable set point device determines the normal temperature. When the normal temperature is indicated, the thermostat controls the temperature modifying load to restore the selected normal 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: 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 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.