LCD controller with capacitive touch interface

• US 9,569,025 B2
• Filed: 04/16/2014
• Issued: 02/14/2017
• Est. Priority Date: 04/16/2014
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Curtis, Keith Edwin
• Primary Examiner(s): Lao, Lun-Yi
• Assistant Examiner(s): DEADERICK, ELLIOTT J
• Application Number:
  US14/254,127
• Publication Number:
  US 20150301663A1
• Time in Patent Office: 1,035 Days
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133308 Support structures for LCD panels, e.g. frames or bezels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer

Abstract

An integrated circuit device has a touch controller with at least one input, a liquid crystal display (LCD) controller with a plurality of outputs, an external interface comprising a plurality of external pins, and a multiplexer operable in a first mode to connect the plurality of external pins with the plurality of outputs of the LCD controller and in a second mode to connect at least one of the plurality of external pins with the touch controller.

Claims

1. An integrated circuit device comprising:

a touch controller comprising at least one input,

a liquid crystal display (LCD) controller comprising a plurality of outputs, wherein the LCD controller is configured to drive a segmented LCD comprising a plurality of segment electrodes and common electrodes wherein each segment electrode and each common electrode is individually accessible for connection, wherein the segment electrodes are arranged in groups spaced apart from each other and wherein at least one group forms a seven-segment display,

a plurality of external connections wherein each segment electrode and each common electrode is coupled with one of said plurality of external connections, and

a multiplexer operable in a first mode to connect said plurality of external connections with said plurality of outputs of the LCD controller and in a second mode to connect at least one of said plurality of external connections connected to a common electrode with said touch controller, wherein the common electrode is used as a touch sensor electrode.

2. The integrated circuit device according to claim 1, further comprising a central processing unit operable to control the multiplexer.

3. The integrated circuit device according to claim 2, further comprising a state machine operable to control the multiplexer.

4. The integrated circuit device according to claim 2, wherein the integrated circuit device is a microcontroller.

5. The integrated circuit device according to claim 1, further comprising a state machine operable to control the multiplexer.

6. The integrated circuit device according to claim 1, wherein when operating in the second mode, a subset of said plurality of external connections are connected together and with said at least one input of said touch controller.

7. The integrated circuit device according to claim 1, wherein the touch controller is a capacitive voltage divider (CVD) controller.

8. The integrated circuit device according to claim 7, further comprising an analog-to-digital converter (ADC) coupled with the CVD controller and said at least one external pin.

9. The integrated circuit device according to claim 8, wherein a sampling capacitor is coupled with the ADC and a controllable driver is coupled with the sampling capacitor and the CVD controller.

10. The integrated circuit device according to claim 8, further comprising a digital-to-analog (DAC) converter coupled with the CVD controller, wherein the ADC is coupled with a first one of the plurality of external pins and the DAC is connected with a second one of the plurality of external pins.

11. The integrated circuit device according to claim 7, wherein the LCD driver and the CVD controller are synchronized.

12. The integrated circuit device according to claim 1, wherein the touch controller comprises a charge time measurement unit, a relaxation oscillator, or an impedance phase shift sensor.

13. A system comprising:

an integrated circuit device according to claim 1,

and

a liquid crystal display having segment electrodes and common electrodes which are each coupled with the external connections of the integrated circuit device.

14. A Liquid crystal display comprising:

an integrated circuit device according to claim 1,

a plurality of segment electrodes, and

a plurality of common electrodes,

wherein the plurality of segment electrodes and the plurality of common electrodes are controlled by the integrated circuit device.

15. The integrated circuit device according to claim 1, wherein a surface area of the common electrode is greater that a surface area of more than one segment electrodes.

16. The integrated circuit device according to claim 15, wherein a surface area of two common electrodes is substantially equal to a surface area of a seven segment electrode group.

17. A method of operating an integrated circuit device coupled with a segmented liquid crystal display (LCD), wherein the segmented LCD comprises a plurality of segment electrodes and common electrodes wherein each segment and each common electrode is individually accessible for connection, wherein the segment electrodes are arranged in groups spaced apart from each other and wherein at least one group forms a seven-segment display, wherein the integrated circuit device comprises a touch controller comprising at least one input, an LCD controller comprising a plurality of outputs, a plurality of external connections coupled with segment electrodes and common electrodes of the segmented LCD, and a multiplexer operable in a first mode to connect said plurality of external pins with said plurality of outputs of the LCD controller and in a second mode to connect at least one of said plurality of external connections which is connected with a common electrode with said touch controller, the method comprising:

a) connecting for a first time period the segment electrodes and the common electrodes by means of the multiplexer with the LCD controller,

b) connecting for a subsequent time period the at least one input of the touch controller with at least one of said common electrodes.

18. The method according to claim 17, further comprising repeating steps a) and b).

19. The method according to claim 17, comprising:

controlling the multiplexer by a central processing unit of the integrated circuit device.

20. The method according to claim 17, comprising:

controlling the multiplexer by a state machine of the integrated circuit device.

21. The method according to claim 17, wherein the touch controller uses a capacitive voltage divider method to determine whether a touch of the LCD has been performed.

22. The method according to claim 21, further comprising synchronizing the LCD controller and the CVD controller.

23. The method according to claim 17, wherein a surface area of the common electrode covers more than one segment electrode.

24. The method according to claim 23, wherein a surface area of two common electrodes is substantially equal to a surface area of a seven segment electrode group.