LIQUID CRYSTAL DISPLAY APPARATUS

• US 20080211787A1
• Filed: 02/15/2008
• Published: 09/04/2008
• Est. Priority Date: 02/20/2007
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Nakao, Kenji, Araki, Shigesumi, Okita, Mitsutaka, Tsuji, Yasuyuki
• Granted Patent: US 8,674,949 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2360/148 the light being detected by light detection means within each pixel
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display apparatus includes a display panel configured to have a plurality of scanning lines for which liquid crystal display elements each containing an optical input device and a display pixel are arranged, respectively, a backlight configured to be arranged facing the display panel to illuminate the display panel, and a control part configured to control writing into the display pixel and reading of a detection signal of the optical input device, wherein the control part displays an external light detection image substantially shielding light from the backlight on the display pixels throughout a first period of a frame period, and displays a display image on the display pixels throughout a second period of the frame period.

Claims

1. A liquid crystal display apparatus comprising:

a display panel configured to have a plurality of scanning lines for which liquid crystal display elements each containing an optical input device and a display pixel are arranged, respectively;

a backlight configured to be arranged facing the display panel to illuminate the display panel; and

a control part configured to control writing into the display pixel and reading of a detection signal of the optical input device, wherein

the control part displays an external light detection image substantially shielding light from the backlight on the display pixels throughout a first period of a frame period, and displays a display image on the display pixels throughout a second period of the frame period.

2. The liquid crystal display apparatus according to claim 1, wherein the control part reads a first detection signal of the optical input device when the first period is started, and reads a second detection signal of the optical input device when the second period is started.

3. The liquid crystal display apparatus according to claim 2, wherein the control part includes an logical operation processing unit which performs logical operation based on a result of reading the first detection signal and a result of reading the second detection signal.

4. The liquid crystal display apparatus according to claim 1, wherein the control part turns off the backlight from a start of the first period of the scanning line up to a termination of the first period of all the scanning lines.

5. The liquid crystal display apparatus according to claim 1, wherein the control part reads out a detection signal of the optical input device at any one of the start of the first period and the start of the second period.

6. The liquid crystal display apparatus according to claim 1, wherein the display pixel is formed by sandwiching an OCB liquid crystal between a pair of electrodes.

7. The liquid crystal display apparatus according to claim 6, wherein the external light detection image is formed by applying a voltage not less than a level at which energy of splay alignment and energy of bend alignment counter-balance between the electrodes.

8. A liquid crystal display apparatus comprising:

a display panel configured to have a plurality of scanning lines for which liquid crystal display elements each containing an optical input device and a display pixel are arranged, respectively;

a backlight configured to be arranged facing the display panel to illuminate the display panel;

a backlight blinking part configured to blink the backlight; and

a control part configured to control writing into the display pixel and reading of a detection signal of the optical input device,

wherein the backlight is configured to be capable of blinking and the control part changes a reference potential synchronously with the blinking of the backlight.

9. The liquid crystal display apparatus according to claim 8, wherein

the control part displays an external light detection image substantially shielding light from the backlight on the display pixels and turns off the backlight throughout a first period of a frame period, and

displays a display image on the display pixel and turns on the backlight throughout a second period of the frame period.

10. The liquid crystal display apparatus according to claim 9, wherein the control part reads out a detection signal from the optical input device when the second period is terminated.

11. The liquid crystal display apparatus according to claim 8, wherein the display pixel is formed by sandwiching an OCB liquid crystal between a pair of electrodes.

12. A liquid crystal display apparatus comprising:

a plurality of liquid crystal display elements which are arranged in a matrix on a substrate, and have respective optical sensors;

a data driving unit which supplies a signal through signal lines arranged in correspondence with the columns of said plurality of liquid crystal display elements;

a data read processing unit which reads and processes a signal corresponding to an amount of received light of the optical sensor through read lines arranged in correspondence with the columns of said plurality of liquid crystal display elements;

a gate line driving unit which supplies a change-over signal for changing over the row of the liquid crystal display element to which a signal from the data driving unit is supplied through a plurality of gate lines arranged in correspondence with the rows of said plurality of liquid crystal display elements; and

a control unit which controls the data driving unit, the data read processing unit and the gate line driving unit, wherein

the control unit includes a video write control unit which controls to write a display video signal by successively scanning the liquid crystal display elements in a predetermined period within one field and write a read video signal by successively scanning the liquid crystal display elements in another period within the one field.

13. The liquid crystal display apparatus according to claim 12, wherein

the optical sensor has a photoelectric conversion device,

the liquid crystal display element has a read unit which outputs a voltage of a capacitor whose charge amount is changed in accordance with the amount of received light in the photoelectric conversion device to the read line,

the data driving unit has pre-charge lines which are arranged in correspondence with the columns of said plurality of liquid crystal display elements in order to charge the capacitor with initial charge, and

the control unit has a read control unit which controls to pre-charge the capacitor with a voltage in correspondence with writing of the read video signal and read out a voltage of the capacitor in correspondence with writing of the display video signal.

14. The liquid crystal display apparatus according to claim 12, wherein a read image to be displayed by the read video signal is displayed in a single gradation.

15. The liquid crystal display apparatus according to claim 12, wherein

a liquid crystal pixel of the liquid crystal display element has an OCB mode liquid crystal, and

a voltage corresponding to the read video signal to be applied to the OCB mode liquid crystal is a value which allows the OCB mode liquid crystal to maintain bend alignment.

16. The liquid crystal display apparatus according to claim 15, wherein a voltage corresponding to the read video signal to be applied to the OCB mode liquid crystal is a value larger than a black-display voltage.