Liquid crystal display with image reading function, image reading method and manufacturing method

• US 6,243,069 B1
• Filed: 02/18/1999
• Issued: 06/05/2001
• Est. Priority Date: 04/22/1997
• Status: Expired due to Term

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Okada, Takashi, Ishikawa, Shinzaburo, Ogawa, Kazufumi, Taketomi, Yoshinao
• Primary Examiner(s): WU, XIAO MIN
• Application Number:
  US09/202,718
• Time in Patent Office: 838 Days
• Field of Search: 345/87, 345/88, 345/89, 345/102, 345/98, 345/100, 345/173, 345/179, 345/180, 345/181, 345/182, 345/103, 345/207, 345/90, 345/92, 345/93
• US Class Current: 345/102
• CPC Class Codes: G02F 1/135 Liquid crystal cells structurally associated with a photoconducting or a ferro-electric layer, the properties of which can be optically or electrically varied G02F1/133348 takes precedence
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: H04N 1/00127 Connection or combination of a still picture apparatus with another apparatus, e.g. for storage, processing or transmission of still picture signals or of information associated with a still picture
• CPC Class Codes: H04N 1/00129 with a display device, e.g. CRT or LCD monitor with a television apparatus H04N1/00283; arrangements for control of display devices G09G
• CPC Class Codes: H04N 1/028 for picture information pick-up
• CPC Class Codes: H04N 1/02805 with photodetectors arranged in a two-dimensional array
• CPC Class Codes: H04N 1/486 with separate detectors, each detector being used for one specific colour component
• CPC Class Codes: H04N 2201/0081 Image reader H04N2201/0091 - H04N2201/0094 take precedence

Abstract

A TFT(L) 26 with n-channel, which is connected to a transparent pixel electrode 24, and a TFT(D) 27 with p-annel, which is connected to a cathode side of a photodiode 25, are connected to a common source line 22 and a common gate line 23 and are composed so that each of them can be controlled in an ON state independently by impressing a positive voltage VL or a negative voltage VD on the gate line 23. A backlight 18 which is provided on a backside of an active matrix panel 13 comprises monochromatic light sources 18a-18c for emitting each monochromatic light of red, blue or green, and a picture of each color is displayed in a time division. While reading a picture, the picture of the components of red, blue and green are read at each simplex pixel by using each of the monochromatic light sources 18a-18c sequentially. A picture at a pixel P1 are read by storing a predetermined electric charge only at the photodiode 25 of the pixel P1 and exposing the photodiode 25 as well as making a liquid crystal layer 14 corresponding to every two pixels P1vertically and horizontally a transmission state, and an original picture is read at all pixels by repeating similar operation at each of pixels which are adjacent to the pixel P1.

Claims

1. A liquid crystal display device with a function of reading a picture comprising:

a plurality of source lines for transferring a picture signal;

a plurality of gate lines for transferring a scanning signal which are provided in a crossing direction with said source lines;

a pixel electrode which is provided corresponding to each crossing section of the source lines and the gate lines;

a first transistor which is connected to the source lines and the gate lines as well as each of the pixel electrodes;

an opposite electrode which is provided opposite to the pixel electrode;

a liquid crystal which is provided between the pixel electrode and the opposite electrode; and

a photo detector for detecting a quantity of a reflected light from an original which is provided corresponding to each of the pixel electrodes;

fiber comprising;

a second transistor which is connected to said source lines and said gate lines as well as one end of the photo detector; and

the other end line which is connected to the other end of the photo detector;

said liquid crystal display device with a function of reading a picture wherein;

a threshold value of a gate voltage in said first transistor and a threshold value of a gate voltage in said second transistor are determined so that at least only the second transistor can be made an ON state.

2. A liquid crystal display device with a function of reading a picture according to claim 1, wherein:

the threshold value of the gate voltage in said first transistor and the threshold value of the gate voltage in said second transistor are determined so that only the first transistor also can be made an ON state.

3. A liquid crystal display device with a function of reading a picture according to claim 2, wherein:

said first transistor and said second transistor are transistors with a reversed polarity of n-channel or p-channel to each other.

4. A liquid crystal display device with a function of reading a picture according to claim 3, wherein:

said first transistor is a transistor with n-channel while said second transistor is a transistor with p-channel.

5. A liquid crystal display device with a function of reading a picture according to claim 1, wherein:

said photo detector detects the quantity of the reflected light from the original by a discharge of an electric charge held beforehand due to the reflected light from the original;

the threshold value of the gate voltage in said first transistor and the threshold value of the gate voltage in said second transistor are determined so that both the first transistor and the second transistor can be made an ON state simultaneously as well; and

said liquid crystal is made a transmission state under an action of an electric field.

6. A liquid crystal display device with a function of reading a picture according to claim 5, wherein:

said first transistor and said second transistor are transistors with the same polarity of n-channel or p-channel as each other; and

a threshold absolute value of the gate voltage in the second transistor is determined lower than that of the gate voltage in the first transistor.

7. A liquid crystal display device with a function of reading a picture according to claim 5, wherein:

a dielectric constant anisotropy of said liquid crystal is negative; and

a pair of polarizers with a different polarized direction from each other are provided on both sides of said liquid crystal.

8. A liquid crystal display device with a function of reading a picture according to claim 5, wherein:

a dielectric constant anisotropy of said liquid crystal is positive; and

a pair of polarizers with the same polarized direction as each other are provided on both sides of said liquid crystal.

9. A liquid crystal display device with a function of reading a picture according to claim 5, comprising:

a photodiode as said photo detector;

wherein;

said photodiode is connected so that a reverse bias voltage can be impressed from the source line through the second transistor in displaying the picture.

10. A liquid crystal display device with a function of reading a picture according to claim 5, wherein:

a voltage which is equal to the source line is impressed on the other end line which is connected to the other end of said photo detector in displaying the picture.

11. A liquid crystal display device with a function of reading a picture according to claim 1, wherein:

a light shielding electrode which is formed on the same substrate as said photo detector is the other end line which is connected to the other end of the photo detector.

12. A liquid crystal display device with a function of reading a picture according to claim 1, comprising:

such in-plane switching system that the pixel electrode and the opposite electrode are formed on the same substrate;

wherein;

said opposite electrode is the other end line which is connected to the other end of the photo detector.

13. A liquid crystal display device with a function of reading a picture according to claim 1, wherein:

a touch sensor for detecting a setting state of the original is further provided on a surface side of the liquid crystal.

14. A liquid crystal display device with a function of reading a picture according to claim 1, further comprising:

a color filter in which a field for transmitting a light of each predetermined color is formed corresponding to said pixel electrode;

wherein;

in displaying the picture, a color picture is displayed with an additive process of a light which is transmitted through the field of each color in said color filter; and

in reading the picture, the color picture is read by irradiating a light to the original through the field of each color in said color filter and detecting the quantity of the reflected light.

15. A liquid crystal display device with a function of reading a picture according to claim 1, further comprising:

a plurality of back light sources for emitting a light of a different color from each other;

wherein;

in displaying the picture, a color picture is displayed by lighting each of said back light sources selectively in sequence and displaying the picture of each color in a time division; and

in reading the picture, the color picture is read by lighting each of said back light sources selectively in sequence and irradiating a light of each color to the original and detecting the quantity of the reflected light of each color from the original.

16. A liquid crystal display device with a function of reading a picture according to claim 1, further comprising:

a color filter in which a display field for transmitting a light of each predetermined color and an illumination field for transmitting a light of all colors are formed corresponding to each pixel; and

a plurality of back light sources for emitting a light of a different color from each other and a light of a white color when they are lit simultaneously;

wherein;

in displaying the picture, a color picture is displayed with an additive process of a light which is transmitted through the display field of each color in said color filter by lighting all of said back light sources as well as making the liquid crystal corresponding to the illumination field in said color filter a shielding state and meanwhile making the liquid crystal corresponding to the display field a transmission state according to the picture signal; and

in reading an original picture, the color picture is read by lighting each of said back light sources selectively in sequence and irradiating a light of each color to the original through the illumination field in said color filter and detecting the quantity of the reflected light of each color from the original as well as making the liquid crystal corresponding to the display field in said color filter the shielding state and meanwhile making the liquid crystal corresponding to the illumination field the transmission state.

17. A method of reading a picture by using a liquid crystal display device with a function of reading a picture comprising:

a plurality of source lines for transferring a picture signal;

a plurality of gate lines for transferring a scanning signal which are provided in a crossing direction with said source lines;

a pixel electrode which is provided corresponding to each crossing section of the source lines and the gate lines;

a first transistor which is connected to the source lines and the gate lines as well as each of the pixel electrodes;

an opposite electrode which is provided opposite to the pixel electrode;

a liquid crystal which is provided between the pixel electrode and the opposite electrode;

a photo detector which is provided corresponding to each of the pixel electrodes for detecting a quantity of a reflected light from an original by a discharge of an electric charge held beforehand due to the reflected light from the original;

a second transistor which is connected to said source lines and said gate lines as well as one end of the photo detector, and

the other end line which is connected to the other end of the photo detector;

said liquid crystal display device with a function of reading a picture wherein;

a threshold value of a gate voltage in said first transistor and a threshold value of a gate voltage in said second transistor are determined so that at least only the second transistor can be made an ON state;

said method comprising the steps of;

impressing a first predetermined voltage on the source line and making the liquid crystal a transmission state by making at least the first transistor the ON state;

impressing a second predetermined voltage on the source line and holding a predetermined electric charge at the photo detector by making at least the second transistor the ON state;

exposing the photo detector to the reflected light from the original; and

detecting a light exposure of the photo detector through the source line by making only the second transistor the ON state after exposing said photo detector.

18. A method of reading a picture by using a liquid crystal display device with a function of reading a picture comprising:

a plurality of source lines for transferring a picture signal;

a plurality of gate lines for transferring a scanning signal which are provided in a crossing direction with said source lines;

a pixel electrode which is provided corresponding to each crossing section of the source lines and the gate lines;

a first transistor which is connected to the source lines and the gate lines as well as each of the pixel electrodes;

an opposite electrode which is provided opposite to the pixel electrode;

a liquid crystal which is provided between the pixel electrode and the opposite electrode;

a photo detector which is provided corresponding to each of the pixel electrodes for detecting a quantity of a reflected light from an original by a discharge of an electric charge held beforehand due to the reflected light from the original;

a second transistor which is connected to said source lines and said gate lines as well as one end of the photo detector; and

the other end line which is connected to the other end of the photo detector;

said liquid crystal display device with a function of reading a picture wherein;

a threshold value of a gate voltage in said first transistor and a threshold value of a gate voltage in said second transistor are determined so that at least only the second transistor can be made an ON state;

the threshold value of the gate voltage in said first transistor and the threshold value of the gate voltage in said second transistor are determined so that both the first transistor and the second transistor can be made the ON state simultaneously as well; and

said liquid crystal is made a transon state under an action of an electric field;

said method wherein;

said first voltage and said second voltage are equal to each other; and

the step of making the liquid crystal the transmission state and the step of holding a predetermined electric charge at the photo detector are executed simultaneously.

19. A method of manufacturing a liquid crystal display device with a function of reading a picture comprising:

a plurality of source lines for transferring a picture signal;

a plurality of gate lines for transferring a scanning signal which are provided in a crossing direction with said source lines;

a pixel electrode which is provided corresponding to each crossing section of the source lines and the gate lines;

a first transistor which is connected to the source lines and the gate lines as well as each of the pixel electrodes;

an opposite electrode which is provided opposite to the pixel electrode;

a liquid crystal which is provided between the pixel electrode and the opposite electrode;

a photo detector for detecting a quantity of a reflected light from an original which is provided corresponding to each of the pixel electrodes;

a second transistor which is connected to said source lines and said gate lines as well as one end of the photo detector; and

the other end line which is connected to the other end of the photo detector;

said liquid crystal display device with a function of reading a picture wherein;

a threshold value of a gate voltage in said first transistor and a threhold value of a gate voltage in said second transistor are determined so that at least only the second transistor can be made an ON state;

said method wherein;

the other end line which is connected to the other end of said photo detector is formed in a process of forming a gate electrode of at least one of the first transistor and the second transistor.

20. A liquid crystal display device with a function of reading a picture comprising:

a plurality of pixel electrodes;

an opposite electrode opposed to the plurality of pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes; and

a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue;

wherein, when displaying a picture, each of said plurality of back light sources is selectively lit to emit said monochromatic light in sequence so that a picture of each of the colors is displayed in time division, whereby a multi-color picture is produced; and

wherein, when reading a picture, each of said plurality of back light sources is selectively lit so that an original picture is irradiated with one of said monochromatic lights in sequence, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

21. A liquid crystal display device with a function of reading a picture comprising:

a plurality of pixel electrodes;

an opposite electrode opposed to the plurality of pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes;

a color filter having a display field transmitting a light of a predetermined color and an illumination field transmitting a light of any color, said display field and said illumination field being provided corresponding to each pixel; and

a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously;

wherein, when displaying a picture, a liquid crystal in a portion corresponding to said illumination field of said color filter blocks light while a liquid crystal in a portion corresponding to said display field transmits light in response to a picture signal, and all of said back light sources are lit to yield additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

wherein, when reading a picture, said liquid crystal in a portion corresponding to said display field of said color filter blocks light while said liquid crystal in a portion corresponding to said illumination field transmits light, each of said back light sources is selectively lit so that an original picture is irradiated in sequence with one of said monochromatic lights through said illumination field of said color filter, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

22. A liquid crystal display device with a function of reading a picture comprising:

a plurality of first pixel electrodes;

an opposite electrode opposed to the plurality of first pixel electrodes;

a liquid crystal provided between the plurality of first pixel electrodes and the opposite electrode;

a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of said first pixel electrodes;

a plurality of second pixel electrodes for illumination provided corresponding to each of said first pixel electrodes;

a second opposite electrode for illumination opposed to said second pixel electrodes;

a color filter having a display field transmitting a light of a predetermined color and an illumination field transmitting a light of any color, said display field being provided corresponding to each of said plurality of pixel electrodes and said illumination field being provided corresponding to each of said second pixel electrodes for illumination; and

a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously;

wherein, when displaying a picture, a voltage between said plurality of second pixel electrodes for illumination and said second opposite electrode for illumination is set at a predetermined voltage such that a light entering said second pixel electrodes is blocked, and all of said back light sources are lit to yield additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

wherein, when reading a picture, a voltage between said plurality of pixel electrodes and said opposite electrode is set at a predetermined voltage such that a light entering said pixel electrodes is blocked, while said voltage between said plurality of second pixel electrodes for illumination and said opposite electrode for illumination is set at a predetermined voltage such that a light entering said second pixel electrodes is transmitted, and each of said back light sources is selectively lit so that an original picture is irradiated in sequence with said monochromatic light of one of said colors through said second pixel electrodes and said illumination field of said color filter, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

23. A liquid crystal display device with a function of reading a picture according to claim 22, further comprising:

a plurality of source lines for transmitting a picture signal;

a plurality of gate lines for transmitting a scanning signal, said gate lines provided in a crossing direction with said source lines;

a plurality of transistors, each connected to each of said pixel electrodes and one of said source lines and one of said sate lines, said plurality of transistors for connecting and disconnecting said source lines and said pixel electrodes in response to the scanning signal provided from said gate lines; and

a switching means connecting and disconnecting said opposite electrode and said second opposite electrode for illumination;

wherein each of said second pixel electrodes for illumination are connected to one of said source lines; and

wherein said liquid crystal transmits light when a predetermined voltage is applied thereto.

24. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of pixel electrodes, an opposite electrode opposed to the plurality of pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes and a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, said method comprising the steps of:

displaying a color picture wherein each of said plurality of back light sources is selectively lit to emit said monochromatic light in sequence so that a picture of each of the colors is displayed in time division, whereby a multi-color picture is produced; and

reading a color picture wherein each of said plurality of back light sources is selectively lit so that an original picture is irradiated with one of said monochromatic lights in sequence, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

25. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of pixel electrodes, an opposite electrode opposed to the plurality of pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes, a color filter having a display field transmitting a light of a predetermined color and an illumination field transmitting a light of any color, said display field and said illumination field being provided corresponding to each pixel, and a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously, said method comprising the steps of:

displaying a color picture wherein a liquid crystal in a portion corresponding to said illumination field of said color filter blocks light while a liquid crystal in a portion corresponding to said display field transmits light in response to a picture signal, and all of said back light sources are lit to yield additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

reading a color picture wherein said liquid crystal in a portion corresponding to said display field of said color filter blocks light while said liquid crystal in a portion corresponding to said illumination field transmits light, each of said back light sources is selectively lit so that an original picture is irradiated in sequence with one of said monochromatic lights through said illumination field of said color filter, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

26. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of first pixel electrodes, an opposite electrode opposed to the plurality of first pixel electrodes, a liquid crystal provided between the plurality of first pixel electrodes and the opposite electrode, a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of said first pixel electrodes, a plurality of second pixel electrodes for illumination provided corresponding to each of said first pixel electrodes, a second opposite electrode for illumination opposed to said second pixel electrodes for illumination, a color filter having display field transmitting a light of a predetermine color and an illumination field transmitting a light of any color, said display field being provided corresponding to each of said plurality of pixel electrodes and said illumination field being provided corresponding to each of said second pixel electrodes for illumination, and a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously, said method comprising the steps of:

displaying a color picture wherein a voltage between said plurality of second pixel electrodes for illumination and said second opposite electrode for illumination is set a predetermined voltage such that a light entering said second pixel electrodes is blocked, and all of said back light sources are lit to yield additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

reading a color picture wherein a voltage between said plurality of pixel electrodes and said opposite electrode is set at a predetermined voltage such that a light entering said pixel electrodes is blocked, while said voltage between said plurality of second pixel electrodes for illumination and said opposite electrode for illumination is set at a predetermined voltage such that a light entering said second pixel electrodes is transmitted, and each of said back light sources is selectively lit so that an original picture is irradiated in sequence with said monochromatic light of one of said colors through said second pixel electrodes and said illumination field of said color filter, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

27. A liquid crystal display device with function of reading a picture comprising:

a plurality of source lines for transmitting a picture signal;

a plurality of gate lines for transmitting a scanning signal, said gate lines provided in a crossing direction with said source lines;

a plurality of pixel electrodes provided corresponding to each intersection of the source lines and the gate lines;

a plurality of first transistors, each connected to one of the source lines and one of the gate lines and each of the pixel electrodes;

an opposite electrode opposed to the pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes;

a plurality of second transistors, each connected to one of said source lines an one of said gate lines and one end of each of the photo detectors;

an other end line connected to the other end of each of the photo detectors; and

a back light source emitting a light for displaying a picture and a light for illuminating the original picture;

wherein, when reading a picture, said liquid crystal is made to transmit light in a single pixel at a time or in a set of pixels not adjacent to each other at a time so that the light from said back light source irradiates the original picture, and a quantity of the reflected light from the original picture is detected by said photo detectors, whereby the original picture is read.

28. A liquid crystal display device with a function of reading a picture according to claim 27, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels, each disposed between every two or more pixels.

29. A liquid crystal display device with a function of reading a picture according to claim 27, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels disposed next to each other along a predetermined direction and each disposed between every two or more pixels along a direction perpendicular to said predetermined direction.

30. A liquid crystal display device with a function of reading a picture according to claim 27, further comprising:

a color filter having a plurality of fields, each transmitting a light of a predetermined color, said plurality of fields provided corresponding to each of said pixel electrodes;

wherein, when displaying a picture, a light transmits through said plurality of fields in said color filter to yield additive color mixture, whereby a multi-color picture is produced; and

when reading a picture, a light transmits through said plurality of fields in said color filter so as to irradiate the original picture and is reflected by the original picture, and the quantity of the reflected light is detected, whereby a multi-color picture is read.

31. A liquid crystal display device with a function of reading a picture comprising:

a plurality of pixel electrodes;

an opposite electrode opposed to the plurality of pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes; and

a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue;

wherein, when displaying a picture, each of said plurality of back light sources is selectively lit to emit said monochromatic light in sequence so that a picture of each of the colors is displayed in time division, whereby a multi-color picture is produced; and

wherein, when reading a picture, each of said plurality of back light sources is selectively lit so that an original picture is irradiated with one of said monochromatic lights in sequence through a single pixel at a time or through a set of pixels not adjacent to each other at a time, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

32. A liquid crystal display device with a function of reading a picture comprising:

a plurality of pixel electrodes;

an opposite electrode opposed to the plurality of pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes;

a color filter having a display field transmitting a light of a predetermined color and an illumination field transmitting a light of any color, said display field and said illumination field being provided corresponding to each pixel; and

a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously;

wherein when displaying a picture, a liquid crystal in a portion corresponding to said illumination field blocks light while a liquid crystal in a portion corresponding to the display field transmits light in response to a picture signal, and all of said back light sources are lit to yield additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

wherein, when reading an original picture, said liquid crystal in a portion corresponding to said display field in said color filter blocks light in all the pixels while said liquid crystal in a portion corresponding to said illumination field transmits light through a single pixel at a time or through a set of pixels not adjacent to each other at a time, each of said back light sources is selectively lit so that the original picture is irradiated with one of said monochromatic lights in sequence through said illumination field in said color filter, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

33. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of source lines for transmitting a picture signal, a plurality of gate lines for transmitting a scanning signal, said gate lines provided in a crossing direction with said source lines, a plurality of pixel electrodes provided corresponding to each intersection of the source lines and the gate lines, a plurality of first transistors, each connected to one of the source lines and one of the gate lines and each of the pixel electrodes, an opposite electrode opposed to the pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes, a plurality of second transistors, each connected to one of said source lines and one of said gate lines and one end of each of the photo detectors, an other end line connected to the other end of each of the photo detectors;

and a back light source emitting a light for displaying a picture and a light for illuminating the original picture, said method comprising;

repeating a plurality of times the step of reading the original picture wherein said liquid crystal is made to transmit light in a single pixel at a time or in a set of pixels not adjacent to each other at a time so that the light from said back light source irradiates the original picture, and a quantity of the reflected light from the original picture is detected by said photo detectors, whereby the original picture is read.

34. A method of displaying and reading a picture according to claim 33, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels, each disposed between every two or more pixels.

35. A method of displaying and reading a picture according to claim 33, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels disposed next to each other along a predetermined direction and each disposed between every two or more pixels along a direction perpendicular to said predetermined direction.

36. A method of displaying and reading a picture according to claim 33, wherein:

said liquid crystal display device further comprises a color filter having a plurality of fields, each transmitting a light of a predetermined color, said plurality of fields provided corresponding to each of said pixel electrodes;

said step of displaying comprises a step such that a light transmits through said plurality of fields in said color filter to yield an additive color mixture, whereby a multi-color picture is produced; and

said step of reading is such that a light transmits through said plurality of fields in said color filter to irradiate the original picture and is reflected by the original picture, and a quantity of the reflected light is detected, whereby a multi-color picture is read.

37. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of pixel electrodes, an opposite electrode opposed to the plurality of pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes, and a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, said method comprising the steps of:

displaying a color picture wherein each of said plurality of back light sources is selectively lit to emit said monochromatic light in sequence so that a picture of each of the colors is displayed in time division, whereby a multi-color picture is produced; and

reading a color picture wherein each of said plurality of back light sources is selectively lit so that an original picture is irradiated with one of said monochromatic lights in sequence through a single pixel at a time or a set of pixels not adjacent to each other at a time, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

38. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of pixel electrodes, an opposite electrode opposed to the plurality of pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors for detecting a quantity of a reflected light from an original picture, each of said photo detectors provided corresponding to each of the pixel electrodes, a color filter having a display field transmitting a light of a predetermined color and an illumination field transmitting a light of any color, said display field an d said illumnation field being provided corresponding to each pixel, and a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously, said method comprising the steps of:

displaying a color picture wherein a liquid crystal in a portion corresponding to said illumination field blocks light while a liquid crystal in a portion corresponding to the display field transmits light in response to a picture signal, and all of said back light sources are lit to yield additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

reading a color picture wherein said liquid crystal in a portion corresponding to said display field of said color filter blocks light in all the pixels while said liquid crystal in a portion corresponding to said illumination field transmits light in a single pixel or a set of pixels not adjacent to each other, each of said back light sources is selectively lit so that an original picture is irradiated in sequence with one of said monochromatic lights through said illumination field of said color filter, and a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

39. A liquid crystal display device with a function of reading a picture comprising:

a plurality of source lines for transmitting a picture signal;

a plurality of gate lines for transmitting a scanning signal, said gate lines provided in a crossing direction with said source lines;

a plurality of pixel electrodes provided corresponding to each intersection of the source lines and the gate lines;

a plurality of first transistors, each connected to one of the source lines and one of the gate lines and each of the pixel electrodes;

an opposite electrode opposed to the pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors, each provided corresponding to each of the pixel electrodes, said photo detectors being ones in which an electric charge retained therein beforehand is discharged by receiving a reflected light from an original picture and thereby a quantity of the reflected light is detected;

a plurality of second transistors, each connected to one of said source lines and one of said gate lines and one end of each of the photo detectors;

an other end line connected to the other end of each of the photo detectors; and

a back light source emitting a light for displaying a picture and a light for illuminating the original picture;

wherein, when reading a picture, said-photo detectors are made to retain an electric charge for a single pixel at a time or for a set of pixels not adjacent to each other at a time, and said liquid crystal is made to transmit light through a single pixel at a time or through a set of pixels not adjacent to each other at a time so that the light from said back light source irradiates the original picture, and a quantity of the reflected light is detected by said photo detectors, whereby the original picture is read.

40. A liquid crystal display device with a function of reading a picture according to claim 39, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels, each disposed between every two or more pixels.

41. A liquid crystal display device with a function of reading a picture according to claim 39, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels disposed next to each other along a predetermined direction and each disposed between every two or more pixels along a direction perpendicular to said predetermined direction.

42. A liquid crystal display device with a function of reading a picture according to claim 39, further comprising:

a color filter having a plurality of fields, each transmitting a light of a predetermined color, said plurality of fields provided corresponding to each of said pixel electrodes;

wherein, when displaying a picture, a light transmits through said plurality of fields in said color filter to yield an additive color mixture, whereby a multi-color picture is produced; and

wherein, when reading a picture, a light transmits through said plurality of fields in said color filter to irradiate the original picture and is reflected by the original picture, and the quantity of the reflected light is detected, whereby a multi-color picture is read.

43. A liquid crystal display device with a function of reading a picture comprising:

a plurality of pixel electrodes;

an opposite electrode opposed to the plurality of pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors, each provided corresponding to each of the pixel electrodes, said photo detectors being ones in which an electric charge retained therein beforehand is discharged by receiving a reflected light from an original picture and thereby a quantity of the reflected light is detected; and

a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue;

wherein, when displaying a picture, each of said plurality of back light sources is selectively lit to emit said monochromatic light in sequence so that a picture of each of the colors is displayed in time division, whereby a multi-color picture is produced; and

wherein, when reading a picture, said photo detectors are made to retain an electric charge for a single pixel at a time or for a set of pixels not adjacent to each other at a time, each of said plurality of back light sources is selectively lit so that an original picture is irradiated with one of said monochromatic lights in sequence through a single pixel at a time or through a set of pixels not adjacent to each other at a time, and a quantity of the reflected light is detected by each of said photo detectors, whereby the original picture is read.

44. A liquid crystal display device with a function of reading a picture comprising:

a plurality of pixel electrodes;

an opposite electrode opposed to the plurality of pixel electrodes;

a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode;

a plurality of photo detectors, each provided corresponding to each of the pixel electrodes, said photo detectors being ones in which an electric charge retained therein beforehand is discharged by receiving a reflected light from an original picture and thereby a quantity of the reflected light is detected;

a color filter having a display field transmitting a light of a predetermined color and an illumination field transmitting a light of any color, said display field and said illumination field being provided corresponding to each pixel; and

a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously;

wherein, when displaying a picture, a liquid crystal in a portion corresponding to said illumination field of said color filter blocks light while a liquid crystal in a portion corresponding to said display field transmits light in response to a picture signal, and all of said back light sources are lit to yield additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

wherein, when reading an original picture, (a) said liquid crystal in a portion corresponding to said display field in said color filter blocks light in all the pixels while said liquid crystal in a portion corresponding to said illumination field transmits light through a single pixel at a time or through a set of pixels not adjacent to each other at a time, (b) said photo detectors are made to retain an electric charge for a single pixel at a time or for a set of pixels not adjacent to each other at a time, (c) each of said back light sources is selectively lit so that the original picture is irradiated with one of said monochromatic lights in sequence through said illumination field in said color filter, and (d) a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.

45. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of source lines for transmitting a picture signal, a plurality of gate lines for transmitting a scanning signal, said gate lines provided in a crossing direction with said source lines, a plurality of pixel electrodes provided corresponding to each intersection of the source lines and the gate lines, a plurality of first transistors, each connected to one of the source lines and one of the gate lines and each of the pixel electrodes, an opposite electrode opposed to the pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors, each provided corresponding to each of the pixel electrodes, said photo detectors being ones in which an electric charge retained therein beforehand is discharged by receiving a reflected light from an original picture and thereby a quantity of the reflected light is detected, a plurality of second transistors, each connected to one of said source lines and one of said gate lines and one end of each of the photo detectors, an other end line connected to the other end of each of the photo detectors, and a back light source emitting a light for displaying a picture and a light for illuminating the original picture, said method comprising:

repeating a plurality of times the step of reading the original picture wherein said photo detectors are made to retain an electric charge for a single pixel at a time or for a set of pixels not adjacent to each other at a time, and said liquid crystal is made to transmit light through a single pixel at a time or through a set of pixels not adjacent to each other at a time so that the light from said back light source irradiates the original picture, and a quantity of the reflected light is detected by said photo detectors, whereby the original picture is read.

46. A method of displaying and reading a picture according to claim 45, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels, each disposed between every two or more pixels.

47. A method of displaying and reading a picture according to claim 45, wherein said set of pixels not adjacent to each other is composed of a plurality of pixels disposed next to each other along a predetermined direction and each disposed between every two or more pixels along a direction perpendicular to said predetermined direction.

48. A method of displaying and reading a picture according to claim 45, wherein:

said liquid crystal display device further comprises a color filter having a plurality of fields, each transmitting a light of a predetermined color, said plurality of fields provided corresponding to each of said pixel electrodes;

said step of displaying comprises a step such that a light transmits through said plurality of fields in said color filter to yield an additive color mixture, whereby a multi-color picture is produced; and

said step of reading is such that a light transmits through said plurality of fields in said color filter to irradiate the original picture and is reflected by the original picture, and a quantity of the reflected light is detected, whereby a multi-color picture is read.

49. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of pixel electrodes, an opposite electrode opposed to the plurality of pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors, each provided corresponding to each of the pixel electrodes, said photo detectors in which an electric charge retained therein beforehand is discharged by receiving a reflected light from an original picture and thereby a quantity of the reflected light is detected, and a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, said method comprising the steps of:

displaying a color picture wherein each of said plurality of back light sources is selectively lit to emit said monochromatic light in sequence so that a picture of each of the colors is displayed in time division, whereby a multi-color picture is produced; and

reading a color picture wherein said photo detectors are made to retain an electric charge for a single pixel at a time or for a set of pixels not adjacent to each other at a time, each of said plurality of back light sources is selectively lit so that an original picture is irradiated with one of said monochromatic lights in sequence through a single pixel at a time or through a set of pixels not adjacent to each other at a time, and a quantity of the reflected light is detected by each of said photo detectors, whereby the original picture is read.

50. A method of displaying and reading a picture by using a liquid crystal display device with a function of reading a picture, said liquid crystal display device comprising a plurality of pixel electrodes, an opposite electrode opposed to the plurality of pixel electrodes, a liquid crystal provided between the plurality of pixel electrodes and the opposite electrode, a plurality of photo detectors, each provided corresponding to each of the pixel electrodes, said photo detectors being ones in which an electric charge retained therein beforehand is discharged by receiving a reflected light from an original picture and thereby a quantity of the reflected light is detected, a color filter having a display field transmitting a light of a predetermined color and an illumination field transmitting a light of any color, said display field and said illumination field being provided corresponding to each pixel, and a plurality of back light sources, each emitting a monochromatic light of one of the colors selected from red, green, and blue, and emitting a light of white color when said back light sources are lit simultaneously, said method comprising the steps of:

displaying a color picture wherein a liquid crystal in a portion corresponding to said illumination field of said color filter blocks light while a liquid crystal in a portion corresponding to said display field transmits light in response to a picture signal, and all of said back light sources are lit to yield an additive color mixture of the colors of the lights being transmitted through said display field of said color filter, whereby a multi-color picture is produced; and

reading a color picture wherein (a) said liquid crystal in a portion corresponding to said display field in said color filter blocks light in all the pixels while said liquid crystal in a portion corresponding to said illumination field transmits light through a single pixel at a time or through a set of pixels not adjacent to each other at a time, (b) said photo detectors are made to retain an electric charge for a single pixel at a time or for a set of pixels not adjacent to each other at a time, (c) each of said back light sources is selectively lit so that the original picture is irradiated with one of said monochromatic lights in sequence through said illumination field in said color filter, and (d) a quantity of each monochromatic light reflected from said original picture is detected by each of said photo detectors, whereby a multi-color picture is read.