Light sensitive display

• US 6,995,743 B2
• Filed: 11/27/2002
• Issued: 02/07/2006
• Est. Priority Date: 02/20/2002
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Planar Systems Incorporated (Leyard Optoelectronic Co., Ltd.)
• Inventors: Abileah, Adiel, Boer, Willem den
• Primary Examiner(s): CHANG, KENT WU
• Application Number:
  US10/307,106
• Publication Number:
  US 20030156087A1
• Time in Patent Office: 1,168 Days
• Field of Search: 345/87, 345 90- 93, 345/103, 345/104, 345/173, 178/18.1, 178/18.11
• US Class Current: 345/104
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/133302 Rigid substrates, e.g. inorganic substrates
• 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 1/133514 Colour filters
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/13394 spacers regularly patterned on the cell subtrate, e.g. walls, pillars G02F1/133377 takes precedence
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G06F 1/1611 to support document holders
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• 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 3/03542 Light pens for emitting or receiving light
• CPC Class Codes: G06F 3/03545 Pens or stylus
• 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: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0488 : using a touch-screen or digitiser, e.g. input of commands through traced gestures
• CPC Class Codes: G06V 40/1318 : using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G09G 2300/0439 : Pixel structures
• CPC Class Codes: G09G 2300/0809 : Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0842 : forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2320/029 : by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0626 : for control of overall brightness
• CPC Class Codes: G09G 2360/144 : the light being ambient light
• CPC Class Codes: G09G 3/3648 : using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal device includes a front electrode layer, a rear electrode layer, and a liquid crystal material located between the front electrode layer and the rear electrode layer. A first and second transistor each includes three terminals. The first transistor is a photo transistor. The first terminal of the first transistor electrically interconnected to a conductive electrode free from additional electrical elements therebetween. The second terminal of the first transistor is electrically interconnected to the conductive electrode free from additional electrical elements therebetween and the second terminal of the first transistor is maintained at the same potential as the conductive electrode. The first terminal of the first transistor and the second terminal of the first transistor electrically interconnected to one another free from additional electrical elements therebetween and the first terminal of the first transistor and the second terminal of the first transistor are maintained at the same potential. The second terminal of the first transistor is a gate of the first transistor. The third terminal of the first transistor electrically interconnected to the first terminal of the second transistor free from additional electrical elements therebetween and maintained at the same potential. The second transistor provides a readout function for the circuit. The second terminal of the second transistor electrically connected to one of the select electrodes. The second terminal of the second transistor is a gate of the second transistor. The third terminal of the second transistor is electrically interconnected to a readout system. The second transistor is substantially inhibited from receiving ambient light thereon. The first transistor is not substantially inhibited from receiving ambient light thereon. The first transistor and the second transistor being together with the rear electrode layer. The readout system determines a region of the device that experiences a change in the light level impinging on the device.

Claims

1. A liquid crystal device comprising:

(a) a front electrode layer;

(b) a rear electrode layer;

(c) a liquid crystal material located between said front electrode layer and said rear electrode layer;

(d) changing an electrical potential between said rear electrode layer and said front electrode layer to selectively modify portions of said liquid crystal material to change the polarization of the light incident thereon;

(e) said rear electrode layer comprising a plurality of select electrodes and a plurality of data electrodes such that one of said select electrodes in combination with a plurality of said data electrodes selectively change said electrical potential for a plurality of different portions of said liquid crystal material;

(f) a first transistor which is a photo transistor comprising;

(i) a first terminal;

(ii) a second terminal;

(iii) a third terminal;

(g) a second transistor comprising;

(i) a first terminal;

(ii) a second terminal;

(iii) a third terminal;

(h) said first terminal of said first transistor electrically interconnected to a conductive electrode free from additional electrical elements therebetween;

(i) said second terminal of said first transistor electrically interconnected to said conductive electrode free from additional electrical elements therebetween and said second terminal of said first transistor is maintained at the same potential as said conductive electrode;

(j) said first terminal of said first transistor and said second terminal of said first transistor electrically interconnected to one another free from additional electrical elements therebetween and said first terminal of said first transistor and said second terminal of said first transistor are maintained at the same potential;

(k) said second terminal of said first transistor is a gate of said first transistor;

(l) said third terminal of said first transistor electrically interconnected to said first terminal of said second transistor free from additional electrical elements therebetween and maintained at the same potential;

(m) said second terminal of said second transistor electrically connected to one of said select electrodes;

(n) said second terminal of said second transistor is a gate of said second transistor;

(o) said third terminal of said second transistor is electrically interconnected to a readout system;

(p) said second transistor is substantially inhibited from receiving ambient light thereon, said first transistor is not substantially inhibited from receiving ambient light thereon;

(q) said first transistor and said second transistor being together with said rear electrode layer; and

(r) said readout system determines a region of said device that experiences a change in the light level greater than and less than the relative background 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 conductive electrode.

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

7. The device of claim 1 wherein said device is an active matrix liquid crystal device.

8. The device of claim 1 wherein said second transistor provides an output in response to a change in the amount of ambient light reaching said first transistor.

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

10. A liquid crystal device comprising:

(a) a front electrode layer;

(b) a rear electrode layer;

(c) a liquid crystal material located between said front electrode layer and said rear electrode layer;

(d) changing an electrical potential between said rear electrode layer and said front electrode layer to selectively modify portions of said liquid crystal material to change the polarization of the light incident thereon;

(e) said rear electrode layer comprising a plurality of select electrodes and a plurality of data electrodes such that one of said select electrodes in combination with a plurality of said data electrodes selectively change said electrical potential for a plurality of different portions of said liquid crystal material;

(f) a first transistor which is a photo transistor comprising;

(i) a first terminal;

(ii) a second terminal;

(iii) a third terminal;

(g) a second transistor comprising;

(ii) a second terminal;

(i) a first terminal;

(iii) a third terminal;

(h) said first terminal of said first transistor electrically interconnected to said second terminal of said first transistor free from additional electrical elements therebetween and said first terminal of said first transistor and said second terminal of said first transistor are maintained at the same potential;

(i) said first terminal of said first transistor and said second terminal of said first transistor electrically interconnected to one of a conductive electrode free from additional electrical elements therebetween and maintained at the same potential and to said first terminal of said second transistor free from additional electrical elements therebetween and maintained at the same potential;

(i) said second terminal of said first transistor is a gate of said first transistor;

(k) said third terminal of said first transistor electrically interconnected to the other of said conductive electrode free from additional electrical elements therebetween and said first terminal of said second transistor free from additional electrical elements therebetween;

(l) said second terminal of said second transistor electrically connected to one of said select electrodes;

(m) said second terminal of said second transistor is a gate of said second transistor;

(n) said third terminal of said second transistor is electrically interconnected to a readout system;

(o) said second transistor is substantially inhibited from receiving ambient light thereon, said first transistor is not substantially inhibited from receiving ambient light thereon;

(p) said first transistor and said second transistor being together with said rear electrode layer; and

(r) said readout system determines a region of said device that experiences a change in the light level greater than and less than the background ambient light.

11. The device of claim 10 wherein at least one of said first transistor and said second transistor is a thin-film transistor.

12. The device of claim 11 wherein said first transistor and said second transistor are thin-film transistors.

13. The device of claim 12 wherein the semiconductor material of said first transistor and said second transistor is amorphous silicon.

14. The device of claim 13 wherein said third terminal of said first transistor is capacitively coupled to said conductive electrode.

15. The device of claim 10 wherein said device is an active matrix liquid crystal device.

16. The device of claim 10 wherein said second transistor provides an output in response to a decrease in the amount of ambient light reaching said first transistor.

17. The device of claim 10 wherein said conductive electrode is said one of said select electrodes.