LCD touchscreen panel with scanning backlight

• US 20080055494A1
• Filed: 09/05/2006
• Published: 03/06/2008
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Cernasov, Andrei
• Granted Patent: US 7,843,516 B2
• Time in Patent Office: Days
• US Class Current: 349/12
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: H03K 17/9629 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 17/9631 using a light source as part of the switch
• CPC Class Codes: H03K 2217/96031 Combination of touch switch and LC display

Abstract

A liquid crystal display (LCD) device (100) having an integrated touchscreen, includes a touchscreen surface and LC layer (20) that are partitioned according to the touchscreen keys (200). A corresponding probe light source (82) and sensor (92) positioned behind each partition is assigned to the corresponding touchscreen key. Each probe light sensor is configured to detect user contact on the touchscreen surface by sensing a reflection of the probe light. To further distinguish between different keys, each key may be made active according to a scanning or timesharing process. In this process, when a particular key is active, the neighboring keys are inactive. The scanning/timesharing process may be performed during a touchscreen mode of operation, which is interleaved with a normal display mode.

Claims

1. A liquid crystal display (LCD) device, comprising:

a casing;

a transparent touchscreen surface held into place by the casing;

a liquid crystal (LC) layer disposed within the casing behind the touchscreen surface; and

at least one probe light sensor disposed within the casing behind the LC layer and configured to detect light transmitted through the touchscreen surface,

wherein the probe light sensor is configured to detect user contact with a touchscreen key based on a light sensing operation.

2. The LCD device of claim 1, wherein the LCD device includes a backlight source configured to transmit backlight through the touchscreen surface to convey information to a user.

3. The LCD device of claim 2, wherein the backlight source comprises a plurality of light-emitting diodes (LEDs) including the probe light source.

4. The LCD device of claim 1, further comprising:

at least one probe light source disposed within the casing behind the LC layer, the light source being configured to transmit a probe light through the touchscreen surface,

wherein the at least one probe light sensor is configured to detect the user contact with a corresponding touchscreen key by sensing a reflection of the probe light from the touchscreen surface.

5. The LCD device of claim 1, wherein at least part of the touchscreen surface is partitioned according to a plurality of touchscreen keys,

the device further comprises a plurality of probe light sources and probe light sensors, and

each touchscreen key is matched up with a corresponding probe light source and probe light sensor.

6. The LCD device of claim 5, wherein each probe light source is a light-emitting diode (LED).

7. The LCD device of claim 5, wherein each probe light source modulates the probe light at a frequency above 50 Hz.

8. The LCD device of claim 5, wherein the each probe light source emits the probe light as an infrared signal.

9. The LCD device of claim 5, wherein each corresponding set of probe light source and probe light sensor is disposed within the casing behind the corresponding touchscreen key.

10. The LCD device of claim 9, wherein

at least part of the LC layer is partitioned according to the touchscreen keys,

the LCD device is configured to operate according to the following interleaved modes:

normal display mode and touchscreen mode, and

each LC layer partition is configured to be selectively transparent and opaque during touchscreen mode, such that

the LC layer partition is transparent while the corresponding touchscreen key is active, thereby providing a probe light opening for the corresponding touchscreen key; and

the LC layer partition is opaque while the corresponding touchscreen key is inactive.

11. The LCD device of claim 10, wherein, the LC layer partitions are configured to provide the probe light opening to the touchscreen keys according to a timesharing scheme during touchscreen mode.

12. The LCD device of claim 11, wherein the touchscreen keys are grouped into blocks, and the LC layer partitions are configured to concurrently provide probe light openings for each block of touchscreen keys, each probe light opening being provided according to a timesharing scheme.

13. The LCD device of claim 10, wherein, during touchscreen mode, each probe signal source is selectively turned on when the corresponding touchscreen key is active and turned off when the corresponding touchscreen key is inactive.

14. The LCD device of claim 13, wherein user contact with a particular touchscreen key is detected when a measured intensity at the corresponding probe light sensor exceeds a predetermined threshold while the touchscreen key is active.

15. The LCD device of claim 14, further comprising:

reference light sensor; and

a reference partition in the LC layer corresponding to the reference light source and reference light detector,

wherein the reference partition is configured to provide a reference light opening during normal mode, through which the reference light sensor measures a reference light intensity, and the threshold is calibrated according to the measured reference light intensity.

16. The LCD device of claim 1, further comprising a plurality of probe light sensors, each probe light sensor configured to detect the user contact with a corresponding touchscreen key by sensing a lack of external light transmitting through the touchscreen surface.

17. A liquid crystal display (LCD) device, comprising:

a casing;

a transparent touchscreen surface held into place by the casing, at least part of the touchscreen surface being partitioned according to touchscreen keys;

a liquid crystal (LC) layer disposed within the casing behind the touchscreen surface, at least part of the LC layer being partitioned according to the touchscreen keys; and

a plurality of probe light sources and probe lights sensor disposed within the casing behind the LC layer, such that each touchscreen key is matched up with a corresponding probe light source and probe light sensor,

wherein user contact with a particular touchscreen key is detected when the corresponding light source transmits a probe light and the corresponding probe light sensor senses a reflection of the probe light from the corresponding partition of the touchscreen surface.

18. The LCD device of claim 17, wherein

the LCD device is configured to operate according to the following interleaved modes:

normal display mode and touchscreen mode, and

each LC layer partition is configured to be selectively transparent and opaque during touchscreen mode, such that;

the LC layer partition is transparent while the corresponding touchscreen key is active, thereby providing a probe light opening for the corresponding touchscreen key; and

the LC layer partition is opaque while the corresponding touchscreen key is inactive.

19. The LCD device of claim 18, wherein the LC layer partitions are configured to provide the probe light opening to the touchscreen keys according to a timesharing scheme during touchscreen mode.

20. The LCD device of claim 18, wherein, during touchscreen mode, each probe signal source is selectively turned on when the corresponding touchscreen key is active and turned off when the corresponding touchscreen key is inactive.

21. The LCD device of claim 18, wherein user contact with a particular touchscreen key is detected when a measured intensity at the corresponding probe light sensor exceeds a predetermined threshold while the touchscreen key is active.

22. A liquid crystal display (LCD) device, which is configured to operate according to a normal display mode and a touchscreen mode in an interleaving manner, the LCD device comprising:

a casing;

a transparent touchscreen surface held into place by the casing, at least part of the touchscreen surface being partitioned according to touchscreen keys;

a liquid crystal (LC) layer disposed within the casing behind the touchscreen surface, at least part of the LC layer being partitioned according to the touchscreen keys; and

a plurality of probe light sources and probe lights sensor disposed within the casing behind the LC layer, such that each touchscreen key is matched up with a corresponding probe light source and probe light sensor,

wherein a probe light opening is selectively provided for each touchscreen key during touchscreen mode by switching the corresponding partition in the LC layer from an opaque state to a transparent state,

and user contact with a particular touchscreen key is detected when the corresponding probe light source transmits a probe light through the probe light opening and the corresponding probe light sensor senses a reflection of the probe light from the corresponding partition of the touchscreen surface.