TFT display, OLED interface and method for detecting the spatial position of extremities in a spatial region located in front of the display

• US 9,766,733 B2
• Filed: 04/18/2011
• Issued: 09/19/2017
• Est. Priority Date: 04/16/2010
• Status: Active Grant

• Current Assignee: Microchip Technology Germany GmbH (Microchip Technology Incorporated)
• Original Assignee: Microchip Technology Germany GmbH (Microchip Technology Incorporated)
• Inventors: Ivanov, Artem
• Primary Examiner(s): McLoone, Peter D
• Application Number:
  US13/641,172
• Publication Number:
  US 20130194519A1
• Time in Patent Office: 2,346 Days
• Field of Search: 345104, 345173, 345174, 345156, 349 12, 341 33, 178 1801
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A liquid crystal display (LCD) includes a plurality of display units formed with a first substrate, a color matrix formed on the first substrate, and a common electrode formed on the color matrix, a second substrate spaced from the first substrate, a pixel electrode matrix formed on the second substrate, a liquid crystal material disposed between the common electrode and the pixel electrode matrix. The LCD includes a touch sensing member integrated onto the color matrix of the first substrate.

Claims

1. A liquid crystal (LC) display, comprising:

a first substrate layer,

a first electrode structure, which comprises a plurality of pixel electrodes and is applied to the first substrate layer,

a liquid crystal filling, and

a single second electrode structure that is designed as a whole area electrode layer and functions as a single counter electrode for the plurality of pixel electrodes,

wherein the LC display is provided with a sensor device comprising a plurality of sensor electrodes arranged in rows and columns for detecting in a touch mode a touch of a finger of a user and in a non-touch mode for detecting the finger or a hand of the user in a region located in front of the LC display thereby causing changes in an electric field, wherein each row and each column comprises a plurality of electrically connected sensor elements and wherein the sensor device is configured to operate in one of the touch mode and the non-touch mode,

wherein when the sensor device operates in the non-touch mode, the second electrode structure functions as the electric field providing electrode for the sensor device receiving an alternating voltage to generate said electric field and wherein at least one row of connected sensor elements and one column of connected sensor elements are selected to each operate as a receiving electrode, wherein signals from the at least one row of connected sensor elements and one column of connected sensor elements operating as a receiving electrodes are used to determine a three-dimensional position above said sensor device,

wherein the alternating voltage fed to the second electrode structure is approximately a square wave signal having a plurality of subsequent rising and falling edges and wherein signals received from the plurality of sensor electrodes are sampled, wherein sampling of the signals received from each sensor electrode is performed with two sampling points per rising and two sampling points per falling edge wherein a first sampling is performed immediately before occurrence of a rising edge or a falling edge and an immediately subsequent second sampling is performed immediately after occurrence of a rising edge or a falling edge and wherein each sampling is performed with a sampling time short enough that the signals received can be assumed to be quasi constant.

2. The LC display of claim 1, wherein the sensor device circuitry-wise at least partially is embedded into a display operating circuitry.

3. The LC display of claim 1, wherein four electrodes are selected which form a frame.

4. The LC display of claim 3, wherein the four electrodes comprise the most left and most right of the column electrodes and the most upper and most lower of the row electrodes.

5. The LC display of claim 1, wherein the display device is configured as a rectangular display, and wherein a top and bottom row of electrodes each form an elongated top and bottom electrode, respectively and a left and right column of electrodes each form an elongated left and right electrode, respectively.

6. The LC display of claim 1, wherein the alternating voltage is a square wave, trapezoidal or similar alternating voltage.

7. The LC display of claim 6, wherein the frequency of the square wave voltage is in the range of 50 Hz to 80 kHz.

8. The LC display of claim 1, wherein the sensor electrodes are designed transparent and are placed above the counter electrode.

9. The LC display of claim 1, further comprising circuitry for switching between the touch mode and the non-touch mode.

10. The LC display of claim 9, wherein the circuitry is provided by an application specific integrated circuit (ASIC).

11. The LC display according to claim 1, wherein the second electrode structure is the outermost electrically conductive layer of the LC display.

12. The LC display of claim 1, wherein the square wave signal has a frequency of about 10 kHz.

13. A sensor circuitry for detecting the presence and/or position of extremities in a region spatially located in front of a liquid crystal (LC) display, comprising:

several measurement electrodes,

an electric field-providing electrode receiving an alternating voltage for generating an electric field which takes effect onto the measurement electrodes in dependence of the presence or position of the above mentioned extremities, and

an evaluation circuitry for detecting field electric effects onto these measurement electrodes,

wherein the electric field-providing electrode is implemented using a VCOM electrode of the LC display, wherein the VCOM electrode is a single electrode substantially covering the LC display,

wherein in a first operating mode, the measurement electrodes are used to perform a touch detection by measuring a capacitance of a measurement electrode or of a capacitance between neighboring electrodes and wherein in a second operating mode some of the electrodes are selected to perform a non-touch detection by measuring variances in the electric field generated by the electric field-providing electrode, wherein signals from the selected measurement electrodes are used to determine a three-dimensional position above said sensor device,

wherein the alternating voltage is approximately a square wave signal having a plurality of subsequent rising and falling edges and wherein subsequent signals received from the plurality of sensor electrodes are sampled immediately before and after each rising and falling edge and wherein each sampling is performed with a sampling time short enough that the signals received can be assumed to be quasi constant.

14. The sensor circuitry according to claim 13, wherein in the second mode four electrodes are selected forming a frame.

15. The sensor circuitry of claim 13, wherein the square wave signal has a frequency of about 10 kHz.

16. A method for detecting the spatial position of extremities in a detection range that extends in front of a thin film transistor (TFT) liquid crystal (LC) display comprising a touch screen with electrode segments arranged in rows and columns, wherein an electric field is generated by means of a field providing electrode receiving an alternating voltage and voltage levels are detected by means of measurement electrodes that are affected by the spatial position of the extremities to be detected, wherein as field providing electrode a single laminar electrode is used, which forms a component part of the LC system of the TFT LC displays and each measurement electrode is formed by selecting a row or column of electrode segments of the touch screen in series, wherein in a first operating mode, the measurement electrodes are used to perform a touch detection and wherein in a second operating mode four electrodes are selected to perform a non-touch detection, wherein signals from the four electrodes are used to determine a three-dimensional position above said sensor device, and wherein the alternating voltage is approximately a square wave signal having a plurality of subsequent rising and falling edges and wherein signals received from the plurality of sensor electrodes are sampled, wherein sampling of the signals received from each sensor electrode is performed with two sampling points per rising and two sampling points per falling edge wherein a first sampling is performed immediately before occurrence of a rising or falling edge and an immediate subsequent second sampling is performed immediately after occurrence of a rising or falling edge and wherein each sampling is performed with a sampling time short enough that the signals received can be assumed to be quasi constant.

17. The method of claim 16, wherein the TFT LC display is operated by a square wave alternating voltage applied to the laminar electrode.

18. The method of claim 16, wherein the voltage at the laminar electrode is in the range of 5V.

19. The method according to claim 16, wherein the touch and non-touch detection are in a sleep mode until a minimum distance to the LC display of the spatial position has been reached.

20. The method according to claim 19, wherein after said minimum distance has been reached the spatial position of extremities are determined until a touch of the LC display occurs whereupon the touch screen electrode segments operate in touch mode to determine an associated touch location.

21. The method according to claim 20, wherein as long as a touch is detected, the non-touch detection is deactivated.

22. The method according to claim 20, wherein touch detection is deactivated until a predetermined distance to a surface of the touch screen is undercut.

23. The method according to claim 16, wherein the field providing electrode structure of the TFT LC display is driven with an alternating voltage having a frequency in the range of 5 kHz to 40 kHz.

24. The method according to claim 16, wherein the field providing electrode structure is the outermost electrically conductive layer of the TFT LC display.

25. The method according to claim 16, wherein the field providing electrode is formed continuously and covers a complete display surface.

26. The method of claim 16, wherein the square wave signal has a frequency of about 10 kHz.

27. A liquid crystal (LC) display, comprising:

a first substrate layer,

a first electrode structure, which comprises a plurality of pixel electrodes and is applied to the first substrate layer,

a liquid crystal filling, and

a second electrode structure that is designed as a whole area electrode layer and functions as a counter electrode for the plurality of pixel electrodes,

wherein the LC display is provided with a sensor device comprising a plurality of sensor electrodes which in a non-touch mode are configured to detect the finger or a hand of the user in a region located in front of the LC display thereby causing changes in an electric field,

wherein the second electrode structure functions as the electric field providing electrode for the sensor device receiving an alternating voltage to generate said electric field,

wherein the alternating voltage is approximately a square wave signal having a plurality of subsequent rising and falling edges and wherein signals received from the plurality of sensor electrodes are sampled, wherein sampling of the signals received from each sensor electrode is performed with only two sampling points per rising and with only two sampling points per falling edge wherein a first sampling is performed immediately before occurrence of a rising or falling edge and a second sampling is performed immediately after occurrence of a rising or falling edge and wherein each sampling is performed with a sampling time short enough that the signals received can be assumed to be quasi constant.

28. The LC display according to claim 27, wherein the second electrode structure of the LC display is driven with an alternating voltage having a frequency in the range of 5 kHz to 40 kHz.

29. The LC display according to claim 27, wherein the second electrode structure is the outermost electrically conductive layer of the LC display.

30. The LC display according to claim 29, wherein the second electrode is formed continuously and covers a complete display surface.

31. The LC display of claim 27, wherein the square wave signal has a frequency of about 10 kHz.