DISPLAY DEVICE

• US 20080018612A1
• Filed: 04/02/2007
• Published: 01/24/2008
• Est. Priority Date: 07/24/2006
• Status: Active Grant

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Toshiba Matsushita Display Technology Co Ltd (Japan Display Incorporated)
• Inventors: Tada, Norio, Nakamura, Hiroki, Hayashi, Hirotaka, Imai, Takayuki, NAKAMURA, Takashi
• Granted Patent: US 7,773,068 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0354 with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

In order to improve accuracy in determining whether or not an object touches a display screen, a display device includes a display unit and a processor. The display unit includes an image display unit which displays an image on a display screen, an optical input unit which picks up an image of an object adjacent to the display screen and a capacitive coupling detector which detects a capacitive coupling to the object adjacent to the display screen. The processor determines that the object touches the display screen by using, and concurrently calculates the coordinates touched by the object by using the capacitive coupling detected by the capacitive coupling detector, and the image picked up by the optical input unit.

Claims

1. A display device comprising:

a display unit including an image display unit configured to display an image on a display screen, an optical input unit configured to pick up an image of an object adjacent to the display screen, and a capacitive coupling detector configured to detect a capacitive coupling to the object adjacent to the display screen; and

a processor configured to determine that the object touches the display screen, and concurrently to calculate the coordinates touched by the object, on the basis of the capacitive coupling detected by the capacitive coupling detector, and of the image picked up by the optical input unit.

2. The display device according to claim 1, further comprising a power supply unit configured to apply a voltage, wherein

the capacitive coupling detector includes a sensor capacitance element,

the power supply unit applies a precharge voltage and a reference voltage respectively to two electrodes of the sensor capacitance element, the precharge voltage and the reference voltage having voltage values oscillating in the same phase, and

the capacitive coupling detector detects the capacitive coupling according to a change in the potential difference across the precharged sensor capacitance element.

3. The display device according to claim 2, wherein

the optical input unit includes an optical sensor connected to the sensor capacitance element in parallel, and

the processor determines the magnitude of the capacitive coupling by using, and calculates the coordinates touched by the object by using a differential image obtained from a difference between an image of a current frame and an image of the previous frame, the images picked up by the optical input unit.

4. The display device according to claim 2, wherein

the display unit is formed on a glass substrate, and

the precharge voltage is applied to a first one of the two electrodes of the sensor capacitance element, the first electrode being formed closer to the glass substrate.

5. The display device according to claim 4, wherein

the first electrode, to which the precharge voltage is applied, has an area larger than the second electrode.

6. The display device according to claim 4, wherein

the first electrode, to which the precharge voltage is applied, is formed of polysilicon.