CAPACITIVE SENSING DEVICE AND CORRESPONDING SHORT CIRCUIT TESTING METHOD

• US 20180313883A1
• Filed: 10/31/2017
• Published: 11/01/2018
• Est. Priority Date: 04/26/2017
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: Wu, Sung-Han, LIM, Wooi Kip, TIEW, Kei Tee, LEONG, KEEN-HUN
• Granted Patent: US 10,613,155 B2
• Time in Patent Office: Days
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: G01R 31/312 by capacitive methods
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G11C 29/025 in signal lines
• CPC Class Codes: G11C 29/50008 of impedance

Abstract

A short circuit testing method for a capacitive sensing device including a plurality of sense lines and a plurality of drive lines includes: under a short circuit testing mode, coupling at least one first line in the sense lines and drive lines to a reference level; using a sensing circuit corresponding to a specific sense line to read out a testing resultant signal; and, comparing the testing resultant signal with a reference signal to determine whether a short circuit exists.

Claims

1. A short circuit testing method of a capacitive sensing device, the capacitive sensing device having a plurality of sense lines and a plurality of drive lines, and the short circuit testing method comprises:

under a short circuit testing mode, coupling at least one first line in the plurality of sense lines and the plurality of drive lines to a reference level;

utilizing a sensing circuit corresponding to a specific sense line to read a testing resultant signal; and

comparing the testing resultant signal with a reference signal to determine whether a short circuit condition occurs in the plurality of sense lines and the plurality of drive lines.

2. The short circuit testing method of claim 1, wherein the step of coupling the at least one first line in the plurality of sense lines and the plurality of drive lines to the reference level comprises:

under the short circuit testing mode, coupling at least another sense line in the sense lines excluding the specific sense line to the reference level; and

the step of determining whether the short circuit condition occurs in the plurality of sense lines and the plurality of drive lines comprises;

comparing the testing resultant signal with the reference signal to determine whether the specific sense line is shorted to the at least one another sense line.

3. The short circuit testing method of claim 1, wherein the step of coupling the at least one first line in the plurality of sense lines and the plurality of drive lines to the reference level comprises:

under the short circuit testing mode, coupling at least one another drive line in the plurality of drive lines excluding a drive line under test to the reference level, the drive line under test being coupled to the specific sense line through a switch; and

the step of determining whether the short circuit condition occurs in the plurality of sense lines and the plurality of drive lines comprises;

comparing the testing resultant signal with the reference signal to determine whether the drive line under test is shorted to the at least one another drive line.

4. The short circuit testing method of claim 1, wherein the step of coupling the at least one first line in the plurality of sense lines and the plurality of drive lines to the reference level comprises:

under the short circuit testing mode, coupling a drive line under test to the reference level; and

the step of determining whether the short circuit condition occurs in the plurality of sense lines and the plurality of drive lines comprises;

comparing the testing resultant signal with the reference signal to determine whether the drive line under test is shorted to a sense line under test.

5. The short circuit testing method of claim 1, wherein the testing resultant signal has a direct-current level, the reference signal is a reference direct-current level, and the step of determining whether the short circuit condition occurs in the plurality of sense lines and the plurality of drive lines comprises:

deciding that the short circuit has occurred in the plurality of sense lines and the plurality of drive lines when detecting that the direct-current level of the testing resultant signal is different from the reference direct-current level.

6. The short circuit testing method of claim 1, wherein the testing resultant signal is an alternating-current signal, and the reference signal is a reference alternating-current signal;

and, the step of determining whether the short circuit condition occurs in the plurality of sense lines and the plurality of drive lines comprises;

deciding that the short circuit has occurred in the plurality of sense lines and the plurality of drive lines when detecting that a peak-to-peak amplitude of the testing resultant signal is different from a peak-to-peak amplitude of the reference alternating-current signal.

7. A capacitive sensing device, comprising:

a plurality of sense lines;

a plurality of drive lines; and

at least one first switch, selectively connected to at least one first line in the plurality of sense lines and the plurality of drive lines;

wherein under a short circuit testing mode, the at least one first switch is arranged to couple the at least one first line to a reference level, and a sensing circuit corresponding to a specific sense line is arranged to read a testing resultant signal so as to perform a short circuit test to determine whether a short circuit condition occurs in the plurality of sense lines and the plurality of drive lines by comparing the testing resultant signal with a reference signal.

8. The capacitive sensing device of claim 7, wherein under the short circuit testing mode, the at least one first switch is arranged to couple at least one another sense line in the plurality of sense lines excluding the specific sense line to the reference level so that the short circuit test is performed by comparing the testing resultant signal with the reference signal to determine whether the specific sense line is shorted to the at least one another sense line.

9. The capacitive sensing device of claim 7, further comprising:

at least one second switch;

wherein under the short circuit testing mode, the at least one first switch is arranged to couple at least one another drive line in the plurality of drive lines excluding a drive line under test to the reference level, and the drive line under test is coupled to the specific sense line through the at least one second switch, so that the short circuit test is performed to determine whether the drive line under test is shorted to at least one another drive line by comparing the testing resultant signal with the reference signal.

10. The capacitive sensing device of claim 7, wherein under the short circuit testing mode, the at least one first switch is arranged to couple a drive line under test to the reference level so that the short circuit test is performed to determine whether the drive line under test is shorted to a sense line under test by comparing the testing resultant signal with the reference signal.

11. The capacitive sensing device of claim 7, wherein the testing resultant signal has a direct-current level, and the reference signal is a reference direct-current level;

and, it is determined that the short circuit has occurred in the plurality of sense lines and the plurality of drive lines when detecting that the direct-current level of the testing resultant signal is different from the reference direct-current level.

12. The capacitive sensing device of claim 7, wherein the testing resultant signal is an alternating-current signal, and the reference signal is a reference alternating-current signal;

and, it is determined that the short circuit has occurred in the plurality of sense lines and the plurality of drive lines when detecting that a peak-to-peak amplitude of the testing resultant signal is different from a peak-to-peak amplitude of the reference alternating-current signal.