Proximity detection matrix display device

• US 20040066367A1
• Filed: 07/30/2003
• Published: 04/08/2004
• Est. Priority Date: 02/13/2001
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thales SA
• Inventors: Fagard, Pierre
• Granted Patent: US 7,319,456 B2
• Time in Patent Office: Days
• US Class Current: 345/156
• 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

The invention concerns an electronic display device comprising means of detection of proximity of a conducting element situated in proximity to a display zone of the device, a set of row electrodes (4) and of column electrodes scanning the display zone, means for generating an excitation of the row electrodes and of the column electrodes as a function of an image to be displayed on the display zone. The proximity detection means comprise:

means (7) for applying a specific electrical signal distinct from the excitation to said set,

means (8) for detecting modifications of the specific electrical signal which are induced by the presence of a conducting element in proximity to a region of the display zone,

and means (15) for determining the position of said region as a function of said detected modifications.

Claims

1. An electronic display device comprising means of detection of proximity of a conducting element situated in proximity to a display zone of the device, a set of row electrodes (4) and of column electrodes (5) scanning the display zone, means for generating an excitation of the row electrodes and of the column electrodes as a function of an image to be displayed on the display zone, characterized in that the proximity detection means comprise:

means (7) for applying a specific electrical signal distinct from the excitation to said set,

means (8) for detecting modifications of the specific electrical signal which are induced by the presence of a conducting element in proximity to a region of the display zone,

and means (15) for determining the position of said region as a function of said detected modifications.

2. The device as claimed in claim 1, characterized in that the row electrodes (4) and the column electrodes (5) respectively form two distinct arrays, in that at least one array of electrodes (4) is chosen for the proximity detection, and in that the means (15) for determining the position of said region define this position as a function of the level of said modifications intervening on the chosen array (4).

3. The device as claimed in claim 1, characterized in that the specific electrical signal is applied both to the rows (4) and to the columns (5), and in that the means (15) for determining the position of said region define this position as a function of at least one row and of at least one column for which said modifications overstep a threshold.

4. The device as claimed in claim 1, characterized in that the electrical signal is applied simultaneously to at least one row electrode (4) and to at least one column electrode (5) and in that couplings between the row electrode (4) and the column electrode (5) are modified when the conducting element is in proximity to the crossover between the row electrode (4) and the column electrode (5).

5. The device as claimed in claim 4, characterized in that the specific electrical signal is applied to said set diagonally.

6. The device as claimed in claim 5, characterized in that the electrical signal is applied to said set along two diagonals of the display zone.

7. The device as claimed in one of the preceding claims, characterized in that the means (15) for determining the position of said region take no account of the modifications unless they intervene on several neighboring electrodes (4, 5).

8. The device as claimed in one of the preceding claims, characterized in that the specific electrical signal is applied successively to various electrodes (4, 5).

9. The device as claimed in one of the preceding claims, characterized in that the electrodes (4, 5) are interdigitated.

10. The device as claimed in one of the preceding claims, characterized in that the conducting element comprises a stylus.

11. The device as claimed in any one of the preceding claims, characterized in that the specific electrical signal has a frequency above 100 kilohertz.

12. The device as claimed in one of the preceding claims, characterized in that it comprises means (16, 30) for driving the display, and in that these means (16, 30) comprise a multiplexer (17) intended to apply an excitation voltage (22) and the specific electrical signal to an electrode (4) selected for the display.

13. The device as claimed in claim 12, characterized in that the means (30) for driving the display furthermore comprise means (7) generating the specific electrical signal, an amplitude demodulator (12) and an analog/digital converter (31), the amplitude demodulator (12) receiving the specific electrical signal and providing the analog/digital converter (31) with a signal representative of said modifications.

14. The device as claimed in one of the preceding claims, characterized in that the electrodes (4, 5) chosen for the detection of proximities receive the electrical signal cyclically.

15. The device as claimed in one of the preceding claims, characterized in that the specific electrical signal is superimposed on the excitation.

16. The device as claimed in one of claims 1 to 14, characterized in that the specific electrical signal is applied to an electrode (4, 5) when the excitation is not applied to this electrode (4, 5).