CALIBRATION METHOD FOR CAPACITANCE LEVEL SENSING APPARATUS AND ANTI-INTERFERENCE METHOD FOR PLURAL CAPACITANCE LEVEL SENSING APPARATUSES

• US 20170038242A1
• Filed: 08/07/2015
• Published: 02/09/2017
• Est. Priority Date: 08/07/2015
• Status: Active Grant

• Current Assignee: Finetek Company Limited
• Original Assignee: Finetek Company Limited
• Inventors: HUANG, Yin-Lun, CHENG, Chao-Kai, LIAO, Chi-Fan, HOU, Yi-Liang
• Granted Patent: US 9,638,570 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01F 23/263 by measuring variations in capacitance of capacitors
• CPC Class Codes: G01F 23/80 Arrangements for signal processing
• CPC Class Codes: G01F 25/20 of apparatus for measuring liquid level

Abstract

A calibration method for a capacitance level sensing apparatus (10) is applied for a tank measurement. A measurement signal generating circuit (102) generates a measurement signal (104) to proceed with the tank measurement. According to a measurement result measured through the measurement signal (104), a sensing circuit (108) transmits a sensing signal (110) to a control unit (112). According to the sensing signal (110), the control unit (112) determines whether the sensing signal (110) is in an effective range or not. If the sensing signal (110) is in the effective range, the control unit (112) sets a total capacitance in accordance with the sensing signal (110) as a measurement base value. If the sensing signal (110) is not in the effective range, the control unit (112) controls the measurement signal generating circuit (102) to adjust a measurement frequency of the measurement signal (104).

Claims

1. A calibration method for a capacitance level sensing apparatus (10) applied for a tank measurement, the calibration method comprising:

a. a measurement signal generating circuit (102) generating a measurement signal (104) to proceed with the tank measurement;

b. according to a measurement result measured through the measurement signal (104), a sensing circuit (108) transmitting a sensing signal (110) to a control unit (112);

c. according to the sensing signal (110), the control unit (112) determining whether the sensing signal (110) is in an effective range or not;

d. if the control unit (112) determines that the sensing signal (110) is in the effective range, the control unit (112) setting a total capacitance in accordance with the sensing signal (110) as a measurement base value; and

e. if the control unit (112) determines that the sensing signal (110) is not in the effective range, the control unit (112) controlling the measurement signal generating circuit (102) to adjust a measurement frequency of the measurement signal (104) until the sensing signal (110) is in the effective range, and then the control unit (112) controlling the measurement signal generating circuit (102) to stop adjusting the measurement frequency of the measurement signal (104).

2. The calibration method in claim 1, wherein the step e comprises:

e1. if the control unit (112) determines that the sensing signal (110) is greater than a maximum of the effective range, the control unit (112) controlling the measurement signal generating circuit (102) to decrease the measurement frequency of the measurement signal (104).

3. The calibration method in claim 2, wherein the step e further comprises:

e2. if the control unit (112) determines that the sensing signal (110) is less than a minimum of the effective range, the control unit (112) controlling the measurement signal generating circuit (102) to increase the measurement frequency of the measurement signal (104).

4. The calibration method in claim 3, wherein in the step e1 and in the step e2, the control unit (112) controls the measurement signal generating circuit (102) to decrease or increase the measurement frequency of the measurement signal (104) with a arithmetic method.

5. An anti-interference method for plural capacitance level sensing apparatuses (12, 14, 16, 18) applied for a tank measurement, the capacitance level sensing apparatus (12, 14, 16, 18) comprising a control unit (112), a measurement signal generating circuit (102) and a sensing circuit (108), the anti-interference method comprising:

p. selecting one of the capacitance level sensing apparatuses (12, 14, 16, 18) as a selected capacitance level sensing apparatus (12);

q. the control unit (112) of the selected capacitance level sensing apparatus (12) obtaining a plurality of reference signal frequency values and a plurality of reference rod capacitances (Cb, Cc, Cd) of the other capacitance level sensing apparatuses (14, 16, 18);

r. according to the reference signal frequency values and the reference rod capacitances (Cb, Cc, Cd) of the other capacitance level sensing apparatuses (14, 16, 18), the control unit (112) of the selected capacitance level sensing apparatus (12) calculating a plurality of reference equivalent capacitances (Cab, Cac, Cad) between the selected capacitance level sensing apparatus (12) and the other capacitance level sensing apparatuses respectively (14, 16, 18);

s. the control unit (112) of the selected capacitance level sensing apparatus (12) calculating the reference equivalent capacitances (Cab, Cac, Cad) and a rod capacitance (Ca) of the selected capacitance level sensing apparatus (12) to obtain a calculation result;

t. the control unit (112) of the selected capacitance level sensing apparatus (12) multiplying the rod capacitance (Ca) of the selected capacitance level sensing apparatus (12) and a proportional constant to obtain a proportional rod capacitance;

u. the control unit (112) of the selected capacitance level sensing apparatus (12) determining whether the calculation result is less than the proportional rod capacitance or not;

v. if the control unit (112) of the selected capacitance level sensing apparatus (12) determines that the calculation result is less than the proportional rod capacitance, the selected capacitance level sensing apparatus (12) being processed by the calibration method in claim 1;

w. if the control unit (112) of the selected capacitance level sensing apparatus (12) determines that the calculation result is not less than the proportional rod capacitance, the selected capacitance level sensing apparatus (12) being processed by the calibration method in claim 1; and

x. if the control unit (112) of the selected capacitance level sensing apparatus (12) determines that the sensing signal (110) is not in the effective range, the control unit (112) of the selected capacitance level sensing apparatus (12) controlling the measurement signal generating circuit (102) of the selected capacitance level sensing apparatus (12) to adjust the measurement frequency of the measurement signal (104), wherein a measurement frequency value of the measurement frequency of the measurement signal (104) is not equal to the reference signal frequency values of the other capacitance level sensing apparatuses (14, 16, 18).

6. The anti-interference method in claim 5, wherein in the step s, the control unit (112) of the selected capacitance level sensing apparatus (12) adds the reference equivalent capacitances (Cab, Cac, Cad) and the rod capacitance (Ca) of the selected capacitance level sensing apparatus (12) to obtain the calculation result.

7. The anti-interference method in claim 6, wherein in the step x, the measurement frequency of the measurement signal (104) is adjusted serially and is decreased or increased by a specific value;

the specific value is at least greater than a percent of a signal frequency value of the selected capacitance level sensing apparatus (12).