Display device having a photosensor and a correction sensor

• US 8,570,302 B2
• Filed: 06/06/2008
• Issued: 10/29/2013
• Est. Priority Date: 06/07/2007
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated), Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Saito, Teruaki, Sato, Hideo, Nishitani, Shigeyuki
• Primary Examiner(s): MANDEVILLE, JASON M
• Application Number:
  US12/155,611
• Publication Number:
  US 20090002341A1
• Time in Patent Office: 1,971 Days
• Field of Search: 345/173, 345/175, 345/176, 345/55, 345/76, 345/81, 345/102
• 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: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/40 OLEDs integrated with touch screens
• CPC Class Codes: H10K 59/60 OLEDs integrated with inorganic light-sensitive elements, e.g. with inorganic solar cells or inorganic photodiodes

Abstract

It is an object of the present invention to allow a specified function to be readily selected in a mobile telephone or the like without performing a complicated operation. A liquid crystal (30) is sandwiched between a TFT substrate (10) and a color filter substrate (20). A photosensor TFT (130) for selecting the function is disposed on the periphery of an effective screen of the TFT substrate (10). A window (24) is provided in a portion of the color filter substrate corresponding to the photosensor TFT (130), and the outside light is blocked as a result of the user touching a finger to the window. A signal from the photosensor is used for selecting the function. A correction sensor TFT (133) is disposed adjacent to the photosensor TFT (130), to thereby eliminating noise caused by the temperature distribution, stray light, or the like, and erroneous operation of the photosensoris prevented.

Claims

1. A display device having a substrate on which pixels are disposed in the form of a matrix on an effective screen, and an image signal applied to each of the pixels is controlled by a thin-film transistor corresponding to the respective pixels, wherein

a photosensor formed using a thin-film transistor is disposed on the substrate on an outside of the effective screen, the photosensor generates a signal as a result of outside light being blocked, and the signal from the photosensor causes the display device to perform a specified function;

a correction sensor formed using a thin-film transistor is formed in the vicinity of the photosensor, and

a light-blocking film is formed over the thin-film transistor of the photosensor for blocking the outside light, wherein an opening part in the light-blocking film is defined only over a drain region of the thin-film transistor of the photosensor such that a photo-electric current is generated in the drain region of the thin-film transistor of the photosensor, and a light-blocking layer is formed over the thin-film transistor of the correction sensor for blocking the outside light.

2. The display device of claim 1, wherein the photosensor and the correction sensor operate as a pair.

3. The display device of claim 1, further comprising:

a plurality of photosensors formed using thin-film transistors being disposed on the substrate on an outside of the effective screen, each generating a signal as a result of outside light being blocked, the signals from the plurality of photosensors causing the display device to perform respective specified functions; and

a plurality of correction sensors formed using thin-film transistors being formed in the vicinity of the plurality of photosensors respectively,

wherein a light-blocking film is formed over the thin-film transistor of each of the plurality of photosensors for blocking the outside light, wherein an opening part in the light-blocking film is defined only over a respective drain region of each of the thin-film transistors of the plurality of photosensors such that a photo-electric current is generated in the respective drain region of each of the thin-film transistors of the plurality of photosensors, and a light-blocking layer is formed over the thin-film transistor of each of the plurality of correction sensors for blocking the outside light.

4. The display device of claim 1, wherein the photosensor and the correction sensor are formed adjacent to each other.

5. The display device of claim 1, wherein the photosensor and the correction sensor are formed by the same process as for the thin-film transistor corresponding to the pixels.

6. The display device of claim 1, wherein the thin-film transistor of the photosensor and the thin-film transistor of the correction sensor are the same size.

10. The display device of claim 1, wherein an organic EL layer is formed on the pixels.

11. The display device of claim 1, wherein

the thin-film transistor of the photosensor has a diode structure in which a gate of the thin-film transistor of the photosensor is connected to a drain or source of the thin-film transistor of the photosensor, and

the thin-film transistor of the correction sensor has a diode structure in which a gate of the thin-film transistor of the correction sensor is connected to a drain or source of the thin-film transistor of the correction sensor.

12. The display device of claim 11, wherein the thin-film transistor of the photosensor is connected in series with the thin-film transistor of the correction sensor.

13. The display device of claim 12, further comprising an output line which outputs the signal, and a second thin-film transistor a drain or source of which is connected to the output line, wherein

the drain or source of the thin-film transistor of the photosensor is connected to the drain or source of the thin-film transistor of the correction sensor via a connecting line;

and

a gate of the second thin-film transistor is connected to the connecting line.

7. A liquid crystal display device having a TFT substrate on which a pixel electrode and a thin-film transistor that controls a signal voltage applied to the pixel electrode are formed in an effective screen, a color filter substrate on which a color filter and a black matrix are formed in an effective screen, a liquid crystal display panel in which an image is formed using a liquid crystal sandwiched between the TFT substrate and the color filter substrate, and a backlight, wherein

a photosensor formed using a thin-film transistor is formed on the TFT substrate on an outside of the effective screen, the photosensor generates a signal as a result of outside light being blocked, and the signal from the photosensor causes the display device to perform a specified function;

a correction sensor formed using a thin-film transistor is formed in the vicinity of the photosensor; and

a light-blocking film for blocking outside light is formed on the color filter substrate in a part corresponding to the photosensor and the correction sensor formed on the TFT substrate, wherein

an opening part in the light-blocking film is formed only in a drain region of the thin-film transistor constituting the photosensor such that a photo-electric current is generated in the drain region of the thin-film transistors constituting the photosensor.

8. The liquid crystal display device of claim 7, wherein the photosensor and the correction sensor are formed by the same process as for the thin-film transistor used for the pixel electrode.

9. The liquid crystal display device of claim 7, wherein the photosensor and the correction sensor operate as a pair.