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Digital thermostat

  • US 4,264,034 A
  • Filed: 08/16/1979
  • Issued: 04/28/1981
  • Est. Priority Date: 08/16/1979
  • Status: Expired due to Term
First Claim
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1. In a digital thermostat having a plurality of liquid crystal display elements, a data transmission circuit for generating a plurality of data signals representative of alphanumeric data, and a plurality of driver conductors interconnecting the data transmission circuit with the liquid crystal display elements, the combination of a control circuit coupled to said data transmission circuit for applying the data signals to the display elements during a display interval and for periodically interrupting the data signals during time and temperature scan intervals, each scan interval having a duration which is less than the turn-off time of the liquid crystal display elements;

  • a strobe circuit coupled to said driver conductors for pulsing the driver conductors during the scan intervals with an electrical strobe signal having a pulse duration less than the turn-on time of the liquid crystal display elements;

    time and temperature set point data return conductors coupled to selected ones of the driver conductors for conducting night-to-day transition, day-to-night transition, day temperature and night temperature data return signals, respectively, in response to the application of a strobe pulse to the corresponding driver conductors; and

    a counting circuit coupled to said strobe circuit and to said set point data return conductors for counting the number of strobe pulses returned through the time set point return conductors during the time scan interval commencing with the first application of a strobe pulse to a driver conductor and terminating with the application of the Nth strobe pulse to a driver conductor, N being the number of present time resolution intervals elapsed since a predetermined reference time, and for counting the number of strobe pulses occurring during the temperature scan interval commencing with the first application of a strobe pulse to a driver conductor and terminating upon the application of a strobe pulse to the driver conductor coupled to the day temperature return conductor in response to a count during the time scan indicating the occurrence of a night-to-day transition, and terminating upon the application of a strobe pulse to the driver conductor coupled to the night temperature return conductor in response to a count during the time scan indicating the occurrence of a day-to-night transition.

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