Methods of Making and Using an Apparatus for Providing Multi-Touch Sensing Capability Using an LCD Screen Without an Extra Touch Screen Layer

• US 20100045635A1
• Filed: 04/10/2009
• Published: 02/25/2010
• Est. Priority Date: 08/25/2008
• Status: Active Grant

• Current Assignee: Chrontel International Ltd., David Soo
• Original Assignee: Chrontel International Ltd.
• Inventors: Soo, David
• Granted Patent: US 8,279,202 B2
• Time in Patent Office: Days
• US Class Current: 345/178
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

The present invention relates to methods of making and using and apparatus for providing touch screen capability using an LCD screen without an extra touch screen layer.

Claims

1. A method of obtaining a visual display of an image and detecting a touch event on an LCD panel that has a plurality of row lines and a plurality of column lines, the method comprising the steps of:

displaying an image on the LCD panel, the step of displaying including transmitting, in a predetermined sequential manner, visual display signals and control signals along the plurality of row lines and the plurality of column lines; and

detecting the touch event using radio frequency touch signals propagated through at least some of the plurality of row lines and some of the plurality of column lines.

2. The method according to claim 1 wherein transmitting the visual display signals and the control signals results in periods of non-use for the displaying for each of the plurality of row lines and the plurality of column lines;

and

wherein the step of detecting the touch event occurs during the periods of non-use for the displaying.

3. The method according to claim 2 wherein the step of detecting the touch event occurs during the periods of non-use for at least some of the plurality of row lines and the plurality of column lines.

4. The method according to claim 2 wherein the step of detecting includes monitoring the propagated radio frequency touch signals to identify a disturbance to the radio frequency touch signals indicative of the touch event.

5. The method according to claim 4 wherein the detected values include detected row values and detected column values:

wherein one difference that exceeds a predetermined threshold between at least one of the detected row values and at least one corresponding row calibration value for radio frequency touch signals propagated along the at least some of the row lines results in a disturbed row line, and

wherein another difference that exceeds another predetermined threshold between at least one of the detected column values and at least one corresponding column calibration value for radio frequency touch signals propagated along at least some of the column lines results in a disturbed column line; and

whereby an intersection of the disturbed row line and the disturbed column line indicates a location of the disturbance, and thereby the touch event on the LCD display panel.

6. The method according to claim 4 wherein the propagated radio frequency touch signals are propagated by being repeatedly transmitted at a predetermined rate so that one of the radio frequency touch signals is propagated through each of the at least some of the plurality of row lines and some of the plurality of column lines during different ones of the periods of non-use.

7. The method according to claim 6, further including the steps of:

initially obtaining at least one calibration value for the some of the plurality of row lines and some of the plurality of column lines by detecting a touch test signal propagated through at least one of the plurality of row lines and the plurality of column lines during a non-touch period;

storing the at least one calibration value; and

wherein the monitoring compares the at least one calibration value to different detected values of the radio frequency touch signals, such that the disturbance is indicated by a difference that exceeds a predetermined threshold between at least one of the detected values and the calibration value.

8. The method according to claim 5 wherein the step of initially obtains at least one row calibration value corresponding to a detected touch test row signal detected during the non-touch period on the plurality of row lines and at least one column calibration value corresponding to a detected touch test column signal detected during the non-touch period on the plurality of column lines.

9. The method according to claim 8 wherein the detected values include detected row values and detected column values:

wherein one difference that exceeds the predetermined threshold between at least one of the detected row values and at least one corresponding row calibration value for radio frequency touch signals propagated along the at least some of the row lines results in a disturbed row line, and

wherein another difference that exceeds the predetermined threshold between at least one of the detected column values and at least one corresponding column calibration value for radio frequency touch signals propagated along at least some of the column lines results in a disturbed column line; and

whereby an intersection of the disturbed row line and the disturbed column line indicates a location of the disturbance, and thereby the touch event on the LCD display panel.

10. The method according to claim 4 wherein the radio frequency touch test signals are one of a sine (or cosine) signal, an arbitrary waveform signal, a combination of a sine and cosine signals, a combination of amplitude-modulated sine and cosine signals, a combination of phase-modulated sine and cosine signals, a combination of frequency-modulated since and cosine signals, a combination of pseudo-random-code modulated sine and cosine signals, and a combination of two orthogonal signals.

11. The method according to claim 10 wherein the radio frequency touch test signal is of one or more different frequency values for each of the plurality of row lines and for each of the plurality of column lines.

12. The method according to claim 6 wherein:

the propagated radio frequency touch signals consist of radio frequency touch transmit signals and result in radio frequency touch receive signals; and

wherein at least one of the following occurs;

each radio frequency touch transmit signal is sent to one of the plurality of row lines and is received as one of the radio frequency touch receive signals by another one of the plurality of row lines; and

each radio frequency touch transmit signal is sent to one of the plurality of column lines and is received as one of the radio frequency touch receive signals by another one of the plurality of column lines.

13. The method according to claim 6 wherein:

the propagated radio frequency touch signals consist of radio frequency touch transmit signals and result in radio frequency touch receive signals; and

wherein at least one of the following occurs;

each radio frequency touch transmit signal is sent to one of the plurality of row lines and is received as one of the radio frequency touch receive signals by one of the plurality of column lines; and

each radio frequency touch transmit signal is sent to one of the plurality of column lines and received by one of the plurality of row lines.

14. The method according to claim 6 wherein:

the propagated radio frequency touch signals consist of radio frequency touch transmit signals and result in radio frequency touch receive signals; and

wherein at least one of the following occurs;

each radio frequency touch transmit signal is sent to one of the plurality of row lines and is received as one of the radio frequency touch receive signals by the one row line; and

each radio frequency touch transmit signal is sent to one of the plurality of column lines and is received by the one column line.

15. The method according to claim 6 wherein:

the propagated radio frequency touch signals consist of radio frequency touch transmit signals and radio frequency touch receive signals; and

wherein at least one of the following occurs;

each radio frequency touch transmit signal is sent to a user'"'"'s body and finger and is received as one of the radio frequency touch receive signals by one of the plurality of row lines; and

each radio frequency touch transmit signal is sent to a user'"'"'s body and finger and is received as one of the radio frequency touch receive signals by one of the plurality of column lines.

16. The method according to claim 6 wherein:

the propagated radio frequency touch signals consist of a radio frequency touch transmit signals and radio frequency touch receive signals; and

wherein at least one of the following occurs;

each radio frequency touch transmit signal is sent to one of the plurality of row lines and is received as one of the radio frequency touch receive signals by a user'"'"'s finger and body; and

each radio frequency touch transmit signal is sent to one of the plurality of column lines and is received as one of the radio frequency touch receive signals by a user'"'"'s finger and body.

17. An apparatus for displaying an image and for sensing a touch event, the apparatus comprising:

an LCD display screen, the LCD display screen including;

a color filter substrate;

a common electrode;

a thin film transistor substrate, the thin film transistor substrate including a plurality of row lines and a plurality of column lines connected to an array of TFT transistors and storage capacitors, wherein an intersection of each of the column line and the row line corresponds to a pixel, thereby forming a plurality of pixels in a matrix;

row and column interface circuits that each operate during a display period and a touch event sensing period, wherein;

during the display period display control signals and display signals are transmitted to the plurality of row lines and the plurality of column lines, respectively, from the row and column interface circuits; and

during the touch event sensing period, at least one of the row and column interface circuits either transmit radio frequency touch transmit signals or receive radio frequency touch receive signals.

18. The apparatus according to claim 17 wherein the touch event sensing period is different than and does not overlap with the display period.

19. The apparatus according to claim 17 wherein the row and column interface circuits, during the touch event sensing period, both transmit radio frequency touch transmit signals and receive radio frequency touch receive signals.

20. The apparatus according to claim 19 wherein the touch event sensing period is different than and does not overlap with the display period.

21. The apparatus according to claim 17 further including:

a display controller circuit, the display controller circuit, in a predetermined sequence, supplies the display control signals via the row interface circuit to the plurality of row lines and the display signals via the column interface circuit to the plurality of column lines for use by each of the pixels to display the image on the display screen; and

a touch screen signal processor circuit that transmits the radio frequency touch transmit signals and receives the radio frequency touch receive signals to and from at least one of the row interface circuit, the column interface circuit and a user'"'"'s body.

22. The apparatus according to claim 19 wherein the predetermined sequence of the display signals and the display control signals results in periods of non-use by the display controller circuit of some of the row lines and some of the column lines;

wherein the touch screen signal processor circuit sends the radio frequency touch transmit signals to at least some of the plurality of row lines and some of the plurality of column lines during the periods of non-use by the display controller of the row lines and the column lines, respectively; and

wherein the touch screen signal processor circuit receives the radio frequency touch receive signals from at least some of the plurality of row lines and some of the plurality of column lines during the periods of non-use by the display controller of the row lines and the column lines, respectively.

23. The apparatus according to claim 22 wherein the touch screen signal processor includes:

a digital waveform generator, one or more digital-to-analog converters, and one or more frequency modulators that generate the radio frequency touch transmit signals; and

one or more frequency modulators, one or more analog-to-digital converters and a touch screen signal detector that receives and process the radio frequency touch receive signals.

24. The apparatus according to claim 23 wherein the digital waveform generator and the touch screen signal detector are implemented by a programmable processor, and wherein the programmable processor executes a software program to generate the radio frequency touch transmit signals and to execute one or more touch detection algorithms.

25. The apparatus according to claim 23 wherein the programmable processor uses non-volatile memory to store one or more calibration values.

26. The apparatus according to claim 22 wherein the touch screen signal processor includes:

one or more signal filters, one or more analog switches and one or more transmit amplifiers that direct the radio frequency touch transmit signals to either the row interface circuit, the column interface circuit, or the user'"'"'s body; and

one or more receive amplifiers, one or more analog switches and one or more signal filters that receives the radio frequency touch receive signals from either the row interface circuit, the column interface circuit or the user'"'"'s body.

27. The apparatus according to claim 17 wherein the row interface circuit includes:

a plurality of high-voltage buffers coupled directly to the plurality of row lines in the display wherein the display control signals are supplied to the row lines, in a predetermined sequence, for the purpose of displaying the image;

a plurality of transmit switches connecting a touch screen transmit signal path to each or some of the plurality of row lines, in another predetermined sequence, for transmitting the radio frequency touch transmit signals to at least some of the plurality of row lines; and

a plurality of receive switches connecting each or some of the plurality of row lines to a touch screen receive signal path, in another predetermined sequence, for routing the radio frequency touch receive signals from at least some of the plurality of row lines;

28. The apparatus according to claim 27 wherein the row interface circuit includes:

a first row interface capacitor which provides ac coupling between a transmit buffer in the transmit signal path and the plurality of transmit switches; and

a second row interface capacitor which provides ac coupling between the plurality of receive switches and a low noise amplifier in the touch receive signal path.

29. The apparatus according to claim 17 wherein the column interface circuit includes:

a plurality of digital-to-analog converters coupled directly to the plurality of column lines in the display wherein the display signals are supplied to the column lines, in a predetermined sequence, for the purpose of displaying the image;

a plurality of transmit switches connecting a touch screen transmit signal path to each or some of the plurality of column lines, in another predetermined sequence, for transmitting the radio frequency touch transmit signals to at least some of the plurality of column lines; and

a plurality of receive switches connecting each or some of the plurality of column lines to a touch screen receive signal path, in another predetermined sequence, for routing the radio frequency touch receive signals from at least some of the plurality of column lines.

30. The apparatus according to claim 29 wherein the column interface circuit includes:

a first column interface capacitor which provides ac coupling between a transmit buffer in the transmit signal path and the plurality of transmit switches; and

a second column interface capacitor which provides ac coupling between the plurality of receive switches and a low noise amplifier in the touch receive signal path.

31. The apparatus according to claim 17 wherein the common electrode is an ITO layer, and where openings are made into the ITO layer directly above the row and column lines to facilitate better penetration of the radio frequency touch signals to a surface of the LCD display screen.

32. The apparatus according to claim 17 wherein the thin film transistor substrate of the LCD display screen is facing the user where touch sensing is required, such that, the radio frequency touch signals is closer to the touch surface.

33. A row interface circuit that couples to a display, the row interface circuit comprising:

a plurality of high-voltage buffers coupled directly to a plurality of row lines in the display wherein display control signals are supplied to the row lines, in a predetermined sequence, for the purpose of displaying the image;

a plurality of transmit switches connecting a touch screen transmit signal path to each or some of the plurality of row lines, in another predetermined sequence, for transmitting the radio frequency touch transmit signals to at least some of the plurality of row lines, during a touch event period that is different than a period used for displaying the image; and

a plurality of receive switches connecting each or some of the plurality of row lines to a touch screen receive signal path, in another predetermined sequence, for routing the radio frequency touch receive signals from at least some of the plurality of row lines, during the touch event period that is different than the period used for displaying the image.

34. The row interface circuit according to claim 33, wherein the plurality of high-voltage buffers, the plurality of transmit switches, and the plurality of receive switches are formed on a single row interface integrated circuit.

35. The row interface circuit according to claim 33 further including:

a first row interface capacitor which provides ac coupling between a transmit buffer in the transmit signal path and the plurality of transmit switches; and

a second row interface capacitor which provides ac coupling between the plurality of receive switches and a low noise amplifier in the touch receive signal path.

36. A column interface circuit that couples to a display, the column interface circuit comprising:

a plurality of digital-to-analog converters coupled directly to a plurality of column lines in the display, wherein display signals are supplied to the column lines, in a predetermined sequence, for the purpose of displaying the image;

a plurality of transmit switches connecting a touch screen transmit signal path to each or some of the plurality of column lines, in another predetermined sequence, for transmitting the radio frequency touch transmit signals to at least some of the plurality of column lines, during a touch event period that is different than a period used for displaying the image; and

a plurality of receive switches connecting each or some of the plurality of column lines to a touch screen receive signal path, in another predetermined sequence, for receiving the radio frequency touch receive signals from at least some of the plurality of column lines, during the touch event period that is different than the period used for displaying the image.

37. The column interface circuit according to claim 36, wherein the plurality of digital-to-analog converters, the plurality of transmit switches, and the plurality of receive switches are formed on a single column interface integrated circuit.

38. The apparatus according to claim 36 wherein the column interface circuit includes:

a first column interface capacitor which provides ac coupling between a transmit buffer in the transmit signal path and the plurality of transmit switches; and

a second column interface capacitor which provides ac coupling between the plurality of receive switches and a low noise amplifier in the touch receive signal path.