Integrated light sensitive liquid crystal display

• US 20070109239A1
• Filed: 11/08/2006
• Published: 05/17/2007
• Est. Priority Date: 11/14/2005
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Abileah, Adiel, den Boer, Willem
• Application Number:
  US11/595,071
• Publication Number:
  US 20070109239A1
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

A liquid crystal device including a front electrode layer, rear electrode layer, a liquid crystal material located between the front electrode layer and the rear electrode layer. A polarizer is located between the liquid crystal material and the front electrode layer and changing an electrical potential between the rear electrode layer and the front electrode layer modifies portions of the liquid crystal material to change the polarization of the light incident thereon. A plurality of light sensitive elements are located together with the rear electrode layer and a processor determines the position of at least one of the plurality of light sensitive elements that has been inhibited from sensing ambient light.

Claims

1. A liquid crystal device comprising:

(a) a front electrode layer;

(b) a rear electrode layer including a photo transistor, a second transistor, and a plurality of electrodes including a plurality of select electrodes and a plurality of data electrodes such that one of said select electrodes in combination with a data electrode selectively change an electrical potential proximate a portion of said rear electrode layer;

(c) a liquid crystal material located between said front electrode layer and said rear electrode layer, portions of said liquid crystal layer selectively modifiable by a changing electrical potential between said rear electrode layer and said front electrode layer to change a polarization of light incident thereon;

(d) a photo transistor exposed to an ambient light and comprising;

(i) a first terminal;

(ii) a gate terminal; and

(iii) a third terminal;

(e) a second transistor substantially inhibited from receiving ambient light and comprising;

(i) a first terminal;

(ii) a gate terminal; and

(iii) a third terminal;

(f) said first terminal of said photo transistor electrically interconnected to a first conductive electrode biased to a first potential;

(g) said gate terminal of said photo transistor electrically interconnected to a second conductive electrode biased to a second potential;

(h) said third terminal of said photo transistor electrically interconnected to and maintained at the potential of said first terminal of said second transistor;

(i) said gate terminal of said second transistor electrically connected to one of said select electrodes; and

(j) a readout system electrically interconnected to said third terminal of said second transistor and determining if said an intensity of light incident to said photo transistor is less than an intensity of said ambient light.

2. The device of claim 1 wherein at least one of said first transistor and said second transistor is a thin-film transistor.

3. The device of claim 2 wherein said first transistor and said second transistor are thin-film transistors.

4. The device of claim 3 wherein the semiconductor material of said first transistor and said second transistor is amorphous silicon.

5. The device of claim 4 wherein said third terminal of said first transistor is capacitively coupled to said second conductive electrode.

6. The device of claim 5 wherein said second conductive electrode has a voltage potential less than said third terminal of said second transistor.

7. The device of claim 1 wherein said first potential exceeds said second potential by a magnitude approximating a negative threshold voltage of said photo transistor.

8. The device of claim 7 wherein said negative threshold voltage of said photo transistor comprises a voltage corresponding to a minimum leakage current for said photo transistor.

9. The device of claim 1 wherein said first potential exceeds said second potential by at least one volt.

10. The device of claim 1 wherein said first potential exceeds said second potential by at least one volt but no more than ten volts.

11. The device of claim 1 wherein said first potential exceeds said second potential by at least four volts but no more than eight volts.

12. The device of claim 1 wherein one of said first potential and said second potential is variable in response to an intensity of ambient light impinging on said liquid crystal device.

13. The device of claim 1 wherein said conductive electrode is said one of said select electrodes.

14. The device of claim 1 wherein a difference of said second potential and said first potential is less than zero volts.

15. The device of claim 1 further comprising a filter inhibiting transmittance of light having a plurality of wavelengths to said photo transistor, said filter not inhibiting the transmittance of light having a wavelength in a blue portion of the visible light spectrum.

16. A photo sensitive structure of liquid crystal display, said photo sensitive structure comprising:

(a) a photo transistor exposed to an ambient light and comprising;

(i) a first terminal biased to a first potential;

(ii) a gate terminal biased to a second potential; and

(iii) a third terminal;

(b) a second transistor substantially inhibited from receiving ambient light and comprising;

(i) a first terminal;

(ii) a gate terminal; and

(iii) a third terminal electrically interconnected to said third terminal of said photo transistor and capacitively connected to said gate terminal of said photo transistor;

(c) a detector responsive to an intensity of an ambient light impinging on said liquid crystal display; and

(d) a processor varying said second potential in response to execution of an instruction relating said intensity of said ambient light detected by said detector to an intensity limit.