Liquid crystal display apparatus

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, thereby an object is detected twice in the first period and the second period,

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, and

the control part includes an logical operation processing unit which performs a logical operation based on a result of reading the first detection signal and a result of reading the second detection signal.

2. 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.

3. 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.

4. 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.

5. The liquid crystal display apparatus according to claim 4 , 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.

6. 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 alternately changes a bias voltage to be given to the optical input device synchronously with the blinking of the backlight, thereby an object is detected from the detection signal in a frame period, and

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.

7. The liquid crystal display apparatus according to claim 6 , wherein the control part reads out a detection signal from the optical input device when the second period is terminated.

8. The liquid crystal display apparatus according to claim 6 , wherein

the display pixel is formed by sandwiching an OCB liquid crystal between a pair of electrodes, and

a black video to be inserted for maintaining a bend alignment for a reverse transition prevention period is used as the external light detection image in the first period.

9. 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 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 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, thereby an object is detected twice in the first period and the second period.