Digital electronic control unit

• US 6,549,866 B1
• Filed: 07/27/2000
• Issued: 04/15/2003
• Est. Priority Date: 07/05/1999
• Status: Expired due to Fees

• Current Assignee: VASU Tech Limited
• Original Assignee: VASU Tech Limited
• Inventors: Bhatnagar, Rajiv
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): SUN, XIUQIN
• Application Number:
  US09/626,578
• Time in Patent Office: 992 Days
• Field of Search: 236/78.R, 364/200, 367/122, 434/236, 210/743, 395/550, 455/553, 702/86
• US Class Current: 702/86
• CPC Class Codes: F24F 11/61 using timers
• CPC Class Codes: G05B 15/02 electric

Abstract

A digital electronic control unit that provides an efficient, miniature, reliable and cost-effective control mechanism for use in household and commercial appliances. It further is capable of real-time-based control, remote control and networking.

Claims

1. A digital electronic control unit for an appliance, comprising:

a plurality of sensor drive circuits, each driving one of a plurality of sensing elements external to said digital electronic control unit, each sensing element converting a sensed parameter to an electrical signal;

an analog multiplexer that receives the electrical signal from each external sensing element and selectively routes a selected electrical signal to a multiplexer output;

an analog-to-digital converter connected to the output of said analog multiplexer and converting the selected electrical signal to digital values;

a linearity, sensitivity and offset correction circuit connected to the output of said analog-to-digital converter for correcting the digital values received from it, using sensor calibration data stored in a non-volatile memory;

a central control unit that receives corrected output from said linearity, sensitivity and offset correction circuit, and generates control signals for operating the appliance, as well as selection signals for controlling said analog multiplexer, using control data supplied by the non-volatile memory;

a digital de-multiplexer connected to an output of said central control unit for selecting one of a plurality of de-multiplexer outputs to which a de-multiplexer input coupled to said central control unit is to be connected;

a plurality of control latches, each connected at one of said de-multiplexer outputs, for storing the digital data received from it and actuating a part of the appliance to adjust the sensed parameter;

a non-volatile memory that stores data and control parameters for the operation of said central control unit, linearity, sensitivity and offset correction circuit.

2. A digital electronic control unit as claimed in claim 1, further comprising a digital noise filter connected to an output of said central control unit for eliminating spurious signals.

3. A digital electronic control unit as claimed in claim 1, further comprising a clock oscillator that provides timing signals for operating circuits of the digital electronic control unit.

4. A digital electronic control unit as claimed in claim 3, wherein said clock oscillator operates at a frequency between approximately 32 KHz and approximately 25 MHz.

5. A digital electronic control unit as claimed in claim 4, wherein the clock oscillator operates at a frequency of 4 MHz.

6. A digital electronic control unit as claimed in claim 1, wherein said sensing elements are linear or non-linear transducers.

7. A digital electronic control unit as claimed in claim 1, wherein said central control unit and said linearity, sensitivity and offset correction circuits are digital logical circuits.

8. A digital electronic control unit as claimed in claim 1, wherein said appliance is a refrigerator and said central control unit includes defrost operation circuits.

9. A digital electronic control unit as claimed in claim 1, wherein said appliance has a single-phase AC motor and said central control unit includes motor start relay circuitry.

10. A digital electronic control unit as claimed in claim 1, wherein the output of each of said control latches is connected to an output drive and protection circuit to drive a switching device to actuate a part of the appliance to adjust the sensed parameter.

11. A digital electronic control unit as claimed in claim 1, a plurality of user input means that are connected to said central control unit through said analog multiplexer, analog-to-digital converter, and linearity, sensitivity and offset correction circuits to provide user-defined inputs and selections for defining desired values of the control parameters.

12. A digital electronic control unit as claimed in claim 1, wherein the user variable means are selected from the group consisting of potentiometers and switches.

13. A digital electronic control unit as claimed in claim 1, further comprising a display drive unit connected to an output of said central control unit for selectively displaying a selected one of the sensed parameter and the user-specified value from the user input means on an external display device.

14. A digital electronic control unit as claimed in claim 1, further comprising an audio drive unit connected to an output of said central control unit for generating audio signals for alerting a user via an audio transducer external to said digital electronic control unit.

15. A digital electronic control unit as claimed in claim 1, further comprising a power supply for powering circuitry of the digital electronic control unit, said power supply including a low-loss capacitive voltage dropping network coupled to a voltage clamping device, a rectifier and a filter network to provide a DC voltage.

16. A digital electronic control unit as claimed in claim 1, where in the entire digital electronic control unit except power supply, sensing elements, user variable means and external switching devices, is implemented as a custom Application Specific Integrated Circuit (ASIC).

17. A digital electronic control unit as claimed in claim 16, wherein the ASIC excludes non-volatile memory but includes a memory interface block for connecting to non-volatile memory external to said digital electronic control unit.

18. A digital electronic control unit as claimed in claim 1, further comprising an output drive and protection circuit having a thermal protection circuit, an over-current protection circuit, over-voltage protection circuit and a soft-start circuit for providing an effective reduced-voltage start-up to a load during an initial period of turn-on.

19. A digital electronic control unit as claimed in claim 1, wherein said appliance is a washing machine.

20. A digital electronic control unit as claimed in claim 1, wherein said appliance is a refrigerator.

21. A digital electronic control unit for an appliance, comprising:

a plurality of sensor drive circuits, each driving one of a plurality of sensing elements external to said digital electronic control unit, each sensing element converting a sensed parameter to an electrical signal;

an analog multiplexer that receives the electrical signal from each external sensing element and selectively routes a selected electrical signal to a multiplexer output;

an analog-to-digital converter connected to said multiplexer output and converting the selected electrical signal to digital values;

a linearity, sensitivity and offset correction circuit connected to the output of said analog-to-digital converter for correcting the digital values received from it, using sensor calibration data stored in a non-volatile memory;

a central control unit receiving the corrected output from said linearity, sensitivity and offset correction circuit, and generating control signals for operating the appliance, as well as selection signals for controlling said analog multiplexer, using control data supplied by the non-volatile memory;

a digital de-multiplexer connected to an output of said central control unit for selecting one of a plurality of de-multiplexer outputs to which a de-multiplexer input coupled to said central control unit is to be connected;

a plurality of control latches, each connected at one output of said digital de-multiplexer, for storing the digital data received from it and actuating a part of the appliance to adjust the sensed parameter;

a non-volatile memory storing the data and control parameters required for the operation of said central control unit and said linearity, sensitivity and offset correction circuit; and

an input of said central control unit is further connected to a device selected from the group consisting of;

a real-time clock providing time-of-day data,

a remote control interface unit receiving user input and providing responses to the user from/to a remote control device, and

a network interface unit providing bidirectional transfer of data between the digital control unit and other devices external to said digital electronic control unit.

22. A digital electronic control unit as claimed in claim 21, further comprising a digital noise filter connected to an output of said central control unit for eliminating spurious signals.

23. A digital electronic control unit as claimed in claim 21, further comprising a clock oscillator that provides timing signals operating circuits of the digital electronic control unit.

24. A digital electronic control unit as claimed in claim 21, wherein said remote control interface unit is of a type selected from the group consisting of:

infra-red, ultrasonic and radio-frequency.

25. A digital electronic control unit as claimed in claim 21, wherein said remote control interface unit is a radio-frequency remote interface unit.

26. A digital electronic control unit as claimed in claim 21, wherein said remote control interface unit is an ultrasonic remote interface unit.

27. A digital electronic control unit as claimed in claim 21, wherein said network interface unit conforms to Transport Control Protocol/Internet Protocol (TCP/IP) standard.

28. A digital electronic control unit as claimed in claim 21, wherein said network interface unit conforms to Controller Area Network (CAN) Bus standard.

29. A digital electronic control unit as claimed in claim 21, wherein said network interface unit is interfaceable to a cable network.

30. A digital electronic control unit as claimed in claim 21, wherein said sensing element are transducers of a type selected from the group consisting of linear and non-linear.

31. A digital electronic control unit as claimed in claim 21, wherein said central control unit and said linearity offset and sensitivity correction circuit are digital logical circuits.

32. A digital electronic control unit as claimed in claim 21, wherein the output of each of said control latches is connected to an output drive and protection circuit to drive a switching device to actuate the necessary part of the appliance in order to correct the sensed parameter.

33. A digital electronic control unit as claimed in claim 21, further comprising a plurality of user input means connected to said central control unit through said analog multiplexer, analog-to-digital converter, and linearity, sensitivity and offset correction circuit to provide user-defined inputs and selections for defining desired values of the control parameters.

34. A digital electronic control unit as claimed in claim 21, wherein the user variable means are selected from the group consisting of potentiometers and switches.

35. A digital electronic control unit as claimed in claim 21, further comprising a display drive unit connected to an output of said central control unit for selectively displaying a selected one of the sensed parameter and a user-specified value from the user input means on a display device external to said digital electronic control unit.

36. A digital electronic control unit as claimed in claim 21, further comprising an audio drive unit connected to an output of said central control unit for generating audio signals for alerting a user via an audio transducer external to said digital electronic control unit.

37. A digital electronic control unit as claimed in claim 21, further comprising a power supply for powering the digital electronic control unit having a low loss capacitive voltage-dropping network coupled to a voltage clamping device, a rectifier and a filter network to provide a DC voltage.

38. A digital electronic control unit as claimed in claim 21, wherein the entire digital electronic control unit including the real-time clock, remote control interface unit and netwok interface unit except power supply, sensing elements, user variable means and external switching devices, is implemented as a custom Application Specific Integrated Circuit (ASIC).

39. A digital electronic control unit as claimed in claim 38, wherein the ASIC excludes non-volatile memory but includes a memory interface block for connecting to non-volatile memory external to said digital electronic control unit.

40. A digital electronic control unit as claimed in claim 21, wherein said output drive and protection circuit includes a thermal protection circuit, an over-current protection circuit, over-voltage protection circuit and a soft-start circuit for providing an effective reduced-voltage start-up to a load during an initial period of turn-on.

41. A digital electronic control unit as claimed in claim 21, wherein said clock oscillator operates at a frequency in a range between approximately 32 KHz and approximately 25 MHz.

42. A digital electronic control unit as claimed in claim 41, wherein said clock oscillator operates at a frequency of 4 MHz.

43. A digital electronic control unit as claimed in claim 21, wherein said appliance is a washing machine.

44. A digital electronic control unit as claimed in claim 21, wherein said appliance is a refrigerator.