Display device including function to input information from screen by light

• US 7,800,594 B2
• Filed: 12/15/2005
• Issued: 09/21/2010
• Est. Priority Date: 02/03/2005
• Status: Active Grant

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Inventors: Yoshida, Masahiro, Kanuma, Toshinori, Ishikawa, Miyuki, Nakamura, Takashi, Hayashi, Hirotaka, Imai, Takayuki
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Shapiro; Leonid
• Application Number:
  US11/300,356
• Publication Number:
  US 20060170658A1
• Time in Patent Office: 1,741 Days
• Field of Search: 345/175, 345/173, 345/166, 345/161
• 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

Abstract

In order to enhance accuracy of determination as to whether an object has contacted a screen and to enhance accuracy of calculation of a coordinate position of the object, edges of an imaged image are detected by an edge detection circuit 76, and by using the edges, it is determined by a contact determination circuit 77 whether or not the object has contacted the screen. Moreover, in order to appropriately control sensitivity of optical sensors in response to external light, by a calibration circuit 93, a drive condition of the optical sensors is changed based on output values of the optical sensors, which are varied in response to the external light.

Claims

1. A display device, comprising:

a display unit configured to display an image on a screen, and is an image of an object which has approached the screen, by using optical sensors; and

a sensor drive unit configured to change a drive condition of the optical sensors based on a statistical amount of output values of the optical sensors,

wherein the sensor drive unit outputs a control signal which controls the drive condition so that upper gradation values including a center in a histogram of gradation values obtained by modulating the output values can be set within a predetermined range,

wherein the sensor drive unit decides the control signal by using a table showing a relationship between an exposure time of the optical sensors, a precharge voltage thereof, and the predetermined range.

2. The display device according to claim 1,

wherein the drive condition is at least one of an exposure time and precharge time of the optical sensors.

3. The display device according to claim 1,

wherein the display unit is one configured to display, on a screen, a region which an object is made to approach, and

the sensor drive unit changes the drive condition based on a statistical amount of output values of the optical sensors arranged in a region on the screen, the region other than the region which the object is made to approach.

4. The display device according to claim 1,

wherein the sensor drive unit is capable changing the upper gradation values in response to sizes of the screen and the object.

5. The display device according to claim 1,

wherein the table is one, in which the exposure time is maximized in an allowable range, and the precharge voltage is changed.

6. The display device according to claim 1,

wherein the sensor drive unit decides the control signal by a linear search method by using the table.

7. The display device according to claim 1,

wherein the sensor drive unit decides the control signal by a binary search method by using the table.

8. The display device according to claim 1,

wherein the sensor drive unit uses gradation values of pixels which have been subjected to thinning processing performed for each of plural regions obtained by partitioning the screen in a fixed range.

9. The display device according to claim 1,

wherein the sensor drive unit provides a predetermined standby period between a point of time when the output values of the optical sensors are changed to an extent where the drive condition of the optical sensors is to be changed and a point of time when the drive condition of the optical sensors is actually changed.

10. The display device according to claim 9, further comprising a hold unit configured to hold the statistical amount during the predetermined standby period.