NON-CONTACT LIQUID LEVEL SENSING SYSTEM FOR HOUSEHOLD ELECTRIC APPLIANCES

• US 20110265562A1
• Filed: 04/30/2010
• Published: 11/03/2011
• Est. Priority Date: 04/30/2010
• Status: Abandoned Application

• Current Assignee: Wing Chung Li
• Original Assignee: Wing Chung Li
• Inventors: LI, Wing Chung
• Application Number:
  US12/770,761
• Publication Number:
  US 20110265562A1
• Time in Patent Office: Days
• US Class Current: 73/304.C
• CPC Class Codes: A47J 2203/00 Devices having filling level indicating means
• CPC Class Codes: A47J 27/212 with signaling means, e.g. whistling kettles
• CPC Class Codes: A47J 31/4457 Water-level indicators
• CPC Class Codes: G01F 23/266 measuring circuits therefor
• CPC Class Codes: G01F 23/268 mounting arrangements of probes

Abstract

A non-contact liquid level sensing system for an electric appliance is provided. The electric appliance includes a liquid container for containing liquid. The non-contact liquid level sensing system includes a micro-controller and a plurality of sensors vertically aligned and mounted to the inside of the liquid container. The micron-controller includes a non-volatile memory for storing data. Each of the sensors includes a circuit board, a sensor pad made of a conductive material mounted on the circuit board, and a cover plate made of a dielectric material covering and being in direct contact with the sensor pad. The micro-controller is electrically connected with the sensors, and configured to measure the capacitance between the sensor pad of each sensor and a reference electric potential, and to determine a liquid level in the liquid tank based on the measured capacitance and the data stored in the non-volatile memory of the micro-controller.

Claims

1. A non-contact liquid level sensing system for an electric appliance, the electric appliance comprising a liquid container for containing liquid, the non-contact liquid level sensing system comprising:

a micro-controller, the micron-controller comprising a non-volatile memory for storing data; and

a plurality of sensors vertically aligned and mounted to the inside of the liquid container, each of the sensors comprising;

a circuit board,

a sensor pad made of a conductive material mounted on the circuit board, and

a cover plate made of a dielectric material covering and being in direct contact with the sensor pad;

wherein;

the micro-controller is electrically connected with the sensors, and configured to measure the capacitance between the sensor pad of each sensor and a reference electric potential, and to determine a liquid level in the liquid tank based on the measured capacitance and the data stored in the non-volatile memory of the micro-controller.

2. The non-contact liquid level sensing system of claim 1, wherein the micro-controller is configured to determine that the liquid level has reached the position of a sensor if the measured capacitance between the sensor pad of the sensor and the reference electric potential is greater than a predetermined value stored in the non-volatile memory of the micro-controller.

3. The non-contact liquid level sensing system of claim 2, wherein the predetermined value is based on the capacitance between the sensor pad of the sensor and the reference electric potential measured by the micro-controller when no liquid is covered on the sensor.

4. The non-contact liquid level sensing system of claim 1, wherein the reference electric potential is a system ground potential for the non-contact liquid level sensing system.

5. The non-contact liquid level sensing system of claim 1 further comprising a display, wherein the micro-controller is electrically connected with the display and configured to display information regarding the determined liquid level on the display.

6. The non-contact liquid level sensing system of claim 1, wherein the micro-controller is configured to control the operation of the electric appliance according to the determined liquid level.

7. The non-contact liquid level sensing system of claim 1, wherein the sensor pad is made of copper.

8. A non-contact liquid level sensing system for an electric appliance, the electric appliance comprising a liquid container for containing liquid and a display, the non-contact liquid level sensing system comprising:

a micro-controller; and

a plurality of sensors vertically aligned and mounted to the inside of the liquid container, each of the sensors comprising;

a circuit board,

a sensor pad made of a conductive material mounted on the circuit board, and

a cover plate made of a dielectric material covering and being in direct contact with the sensor pad;

wherein;

the micro-controller is electrically connected with the sensors and the display, and configured to measure the capacitance between the sensor pad of each sensor and a reference electric potential, to thereby determine a liquid level in the liquid tank, and to display information regarding the determined liquid level on the display.

9. The non-contact liquid level sensing system of claim 8, wherein the micro-controller is configured to determine that the liquid level has reached the position of a sensor if the measured capacitance between the sensor pad of the sensor and the reference electric potential is greater than a predetermined value.

10. The non-contact liquid level sensing system of claim 9, wherein the predetermined value is based on the capacitance between the sensor pad of the sensor and the reference electric potential measured by the micro-controller when no liquid is covered on the sensor.

11. The non-contact liquid level sensing system of claim 8, wherein the reference electric potential is a system ground potential for the non-contact liquid level sensing system.

12. The non-contact liquid level sensing system of claim 8, wherein the micro-controller is configured to control the operation of the electric appliance according to the determined liquid level.

13. The non-contact liquid level sensing system of claim 8, wherein the sensor pad is made of copper.

14. A non-contact liquid level sensing system for an electric appliance, the electric appliance comprising a liquid container for containing liquid, the non-contact liquid level sensing system comprising:

a micro-controller; and

a plurality of sensors vertically aligned and mounted to the inside of the liquid container, each of the sensors comprising;

a circuit board,

a sensor pad made of a conductive material mounted on the circuit board, and

a cover plate made of a dielectric material covering and being in direct contact with the sensor pad;

wherein;

the micro-controller is electrically connected with the sensors, and configured to measure the capacitance between the sensor pad of each sensor and a reference electric potential, to thereby determine a liquid level in the liquid tank, and to control the operation of the electric appliance according to the determined liquid level.

15. The non-contact liquid level sensing system of claim 14, wherein the micro-controller is configured to determine that the liquid level has reached the position of a sensor if the measured capacitance between the sensor pad of the sensor and the reference electric potential is greater than a predetermined value.

16. The non-contact liquid level sensing system of claim 15, wherein the predetermined value is based on the capacitance between the sensor pad of the sensor and the reference electric potential measured by the micro-controller when no liquid is covered on the sensor.

17. The non-contact liquid level sensing system of claim 16, wherein the micron-controller comprises a non-volatile memory and the predetermined value is stored in the non-volatile memory of the micro-controller.

18. The non-contact liquid level sensing system of claim 14, wherein the reference electric potential is a system ground potential for the non-contact liquid level sensing system.

19. The non-contact liquid level sensing system of claim 14, wherein the sensor pad is made of copper.

20. The non-contact liquid level sensing system of claim 14 further comprising a control panel, wherein the micro-controller is configured to receive a command from a user from the control panel and control the operation of the electric appliance based on the determined liquid level and the user'"'"'s command.