JP3406218B2 - Liquid crystal display - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device having an additional function such as an information input function.

[0002]

2. Description of the Related Art Conventionally, a display device for displaying an image signal such as a liquid crystal display device and an image reading device for reading out the image signal with an image sensor such as a CCD have been separately configured. On the other hand, Japanese Patent Application Laid-Open No. 6-18846 discloses an input / output device in which a matrix type liquid crystal display panel is integrally formed with a thin film input element such as a photoelectric conversion element. Specifically, in this input / output device, as shown in FIG. 5, an image reading unit 51 and an image display unit 52 are arranged side by side on the same substrate. Photoelectric conversion elements 54 connected to thin film transistors (TFTs) 53 are arranged in a matrix in the image reading unit 51, and pixel capacitors 56 serving as a load connected to the TFT 55 are arranged in a matrix in the image display unit 52. Are arranged in. In this conventional example, an image reading unit 51 and an image display unit 52 are provided in one device.
And are configured to miniaturize the device.

[0003]

However, in this conventional example, as shown in FIG. 5, the image reading section 51 and the image display section 52 are independently configured, and the respective sections are arranged side by side in a plane. Therefore, there is a problem that the device cannot be downsized due to structural restrictions.

The present invention solves the above-mentioned problems of the prior art, and provides a liquid crystal display device which has an additional function such as an information input function in addition to the display function and which can be downsized. To aim.

[0005]

A liquid crystal display device according to the present invention includes a pixel electrode, a switching element connected to the pixel electrode, a scanning line for driving the switching element, and the switching element. A liquid crystal display device in which a liquid crystal layer is sandwiched between an active matrix substrate in which signal lines for inputting a signal to the pixel electrode are arranged in a matrix and an opposite substrate provided with an opposite electrode. And a pixel signal storage unit for storing the pixel signal read out by the reading unit, and the pixel signal storing unit for storing the pixel signal read out by the reading unit. Is achieved.

[0006] Preferably, it is configured to have an information changing means for changing the information written in the pixel electrode.

Further, preferably, the switching element comprises a thin film transistor, and a liquid crystal driving driver is integrally formed on the active matrix substrate.

Further, preferably, at least one of the reading means and the pixel signal storage means is integrally formed on the active matrix substrate.

Further, preferably, a plurality of the pixel signal storage means are provided, and at least one of the pixel signal storage means,
A comparing unit that stores the signal written as reference data in the pixel electrode as a read comparison signal by the reading unit and compares the pixel signal stored as information data in the other pixel signal storage unit with the comparison signal. It is assumed to have.

Further, preferably, there is provided a data processing means for applying a predetermined data processing to the pixel signal read by the reading means to obtain a display output signal.

Further, preferably, the switching element comprises a field effect transistor, and the field effect transistor is provided with an irradiation means for irradiating light from the outside, and information for changing the information written in the pixel electrode by the irradiation means. It is configured to have a changing means. When irradiating the field effect transistor with light, the light is applied to the low concentration impurity implantation region or the impurity non-implantation region formed between the channel region or the source region and the channel region and between the drain region and the channel region. It is good to irradiate.

Further, preferably, the irradiation means is provided with a light source outside the counter substrate, and light from the light source passes through the counter substrate and the active matrix substrate and is installed outside the active matrix substrate. The reflected light reflected by the read object is used.

Preferably, a light source for liquid crystal display is used as the light source in the irradiating means, and the light intensity of the light source is changed depending on whether the information is displayed or the information is changed by the information changing means. The configuration has a light intensity changing unit.

Further, it is preferable that the data processing means has a data conversion function of mirror-reversing the information changed by the reflected light. That is, when detecting an image signal that is changed by reflected light whose intensity is modulated according to the lightness or darkness of an image of an original document or a character that is the object to be read, and converting the detection signal into an image signal, the image signal The screen information configured by is mirror-inverted with the screen as a plane of symmetry and displayed on the screen.

Preferably, the irradiation means is:
A light source having a spot diameter corresponding to the size of one or a plurality of pixels is used.

[0016] Further, preferably, it is configured to have means for increasing or decreasing the size of the spot diameter.

Preferably, a light emitting diode, a semiconductor laser, or the like is used as a light source having a spot diameter corresponding to the size of one or a plurality of pixels, and a filter which transmits only a wavelength in the vicinity thereof is provided on the active matrix substrate. The structure is formed below the thin film transistor of (1) above while avoiding the formation region of the pixel electrode.

Preferably, the switching element is formed of a thin film transistor, a liquid crystal driving driver is integrally formed on the active matrix substrate, and
At least one of the readout unit, the pixel signal storage unit, the comparison unit, and the data processing unit is integrally formed on the active matrix substrate.

Further, it is preferable that the thin film transistor has a structure for shielding the external light from the front surface and the back surface, and a surface having a larger light shielding effect is the incident surface side of the light source for liquid crystal display.

The operation of the present invention will be described below.

According to the above structure, contrary to the case of writing the image signal, the reading means reads the information written in the pixel electrode as a pixel signal through the signal line, and the pixel signal storage means uses the reading means. The read pixel signal is stored.

Further, the data processing means performs predetermined data processing on the pixel signal read out by the reading means as information data, for example, noise removal, signal level conversion, or data conversion into mirror-inverted data. Then, a display output signal for driving the liquid crystal can be generated.

Further, a plurality of pixel signal storage means are provided, and the signal written in the pixel electrode as reference data is stored as a read comparison signal by the read means in at least one of the pixel signal storage means, and is stored in other pixel signal storage means as information data. By comparing the stored pixel signal with this comparison signal by the comparison means, it is possible to obtain information data from which noise and the like have been removed.

Further, the information changing means changes the information written in the pixel electrode. Specifically, for example, when the light from the irradiation means is incident on the channel region, the low-concentration impurity-implanted region, or the impurity-non-implanted region of the field effect transistor on the active matrix substrate, photoexcitation causes carrier generation to increase the off current. As a result, the charges written in the pixel electrode leak through the field effect transistor,
The charges accumulated in the pixel electrode fluctuate according to the intensity of the light with which the field effect transistor is irradiated from the irradiation means. By reading out the electric charges accumulated in the pixel electrode after the change by the read-out means, it is possible to detect the changed information corresponding to the intensity of the light emitted from the irradiation means.

A light source for liquid crystal display is used as a light source of the irradiating means, and light from this light source passes through the counter substrate and the active matrix substrate and is reflected on a document or the like which is an object to be read and is placed outside thereof. It is also possible to adopt a configuration in which the reflected light is used as an irradiation means and the reflected light is incident on the field effect transistor of the active matrix substrate to increase the off-current of the field effect transistor and change the information written in the pixel electrode. it can.

In this case, when the data processing means data-converts the information changed by the reflected light and mirror-inverts the information, this information becomes the same information as the object to be read.

If the light intensity changing means for changing the light intensity of the light source is used for displaying and for changing the information by the information changing means, the light intensity of the reflected light at the time of sampling the information is changed. The desired value can be achieved, and the SN ratio is improved.

Further, a light source having a spot diameter corresponding to the size of one or a plurality of pixels is used as the irradiation means. Then, when this particular spot light is applied to a specific pixel of the liquid crystal panel, the off-current of the corresponding field effect transistor increases and leakage occurs. As a result, the pixel signal of the irradiated pixel has a different value from the pixel signal of the non-irradiated pixel. Therefore, by reading the information data stored in the pixel signal storage means by the reading means, which pixel It is possible to detect whether or not the spot light is radiated on. Therefore, the irradiation position of the spot light can be displayed on the screen by reading out without performing the data processing of mirror inversion by the data processing circuit.

If the size of the light source of the spot light can be controlled by means of increasing / decreasing the size of the spot diameter, the position of the spot light can be displayed at a desired size, so that the visibility is improved.

Further, in order to effectively irradiate the field effect transistor with the spot light, if a filter that transmits only the vicinity of the wavelength of the light source of the spot light is formed so as to cover the field effect transistor, it becomes a field effect transistor. The incident sensitivity can be increased as compared with the case where other ambient light is incident.

The liquid crystal display device of the present invention can be made into a so-called driver monolithic by integrating and integrally forming a driver for liquid crystal driving on an active matrix substrate made of a thin film transistor using polycrystalline silicon. This is because polycrystalline silicon has a relatively large field effect mobility compared to amorphous silicon, and by increasing the crystal grain size, higher field effect mobility can be obtained, and high frequency switching required for driver logic is possible. Depends on.

On the same substrate of this driver monolithic liquid crystal display device, the above-mentioned reading means, pixel signal storage means,
At least one of the comparison means and the data processing means can be integrally formed. As a result, each circuit of the liquid crystal display device can be integrated and integrated, so that the liquid crystal display device having an additional function such as an information input function can be downsized. Further, high-speed display is possible in the liquid crystal display device.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings.

In the liquid crystal display device of the present invention, a pixel electrode, a switching element connected to the pixel electrode, a scanning line for driving the switching element, and a signal input to the pixel electrode via the switching element. The liquid crystal layer is sandwiched between the active matrix substrate in which the signal lines are arranged in a matrix and the counter substrate provided with the counter electrodes, and the information written in the pixel electrodes is transferred to the pixel signals through the signal lines. And a pixel signal storage means for storing the pixel signal read by the reading means.

Specifically, for example, as shown in FIG.
TFT which is a field effect transistor (FET) using an active matrix type liquid crystal display device as a switching element
3, the pixel capacitance 2 and the pixel TFT 3 connected to the pixel capacitance 2 are arranged in a matrix on the screen portion 1. The gate electrode of each pixel TFT 3 is connected to a gate line 4 which is a scanning line of a gate driver 6 which is a scanning circuit, and the source electrode is connected to a data line 5 which is a signal line of a data driver 7 which is a hold circuit. .
The data line 5 is connected to the video line 8 via the switch 9, and the video line 8 and the gate driver 6 are connected.
A data driver 7 such as a pulse generation circuit is connected to the drive controller 10. A video signal and a sync signal are input to the drive control unit 10, and drive control of the gate driver 6 and the data driver 7 and output control to the video line 8 are performed.

The other end of the video line 8 is switched to the read mode by the contact switching of the mode changeover switch 11 and the sensing circuit 12 constituting the read means at the b contact.
The c-contact in the output mode is selectively connected to the output of the amplifier circuit 18 or the a-contact in the normal display mode.
The output of the sensing circuit 12 is selectively connected to the first pixel signal memory 14 or the second pixel signal memory 15 via the switch 13 that switches between the d contact and the e contact, and these pixel signal memories 14 and 15 are connected. The output of is connected to the comparison circuit 16. The output of the comparison circuit 16 is connected to the data processing circuit 17 which generates a video signal for driving the liquid crystal by data processing, and the output thereof is connected to the c contact of the mode changeover switch 11 via the amplification circuit 18. .

Here, the pixel capacitor 2 is mainly composed of a liquid crystal material sandwiched between these two opposing electrodes with the pixel electrode serving as one electrode and the other electrode serving as a counter electrode formed on a counter substrate. It consists of a dielectric liquid crystal capacitor.

In the above structure, the drive control section 10 to which the video signal and the synchronizing signal are input, controls the drive of the gate driver 6 and the data driver 7, and the video line 8.
Control the output of the video signal to. The gate line 4 is driven by the gate driver 6 and is sequentially selected by pulse signals. In synchronization with this selection timing, the data driver 7 is activated within the period in which each gate line 4 is selected.
To output a selection pulse for sequentially selecting the switches 9 for driving the data lines 5. The image signal from the video line 8 is input to the selected data line 5 through the switch 9 and then to each data line 5, and the selected gate line 4 is selected.
The data is written in the pixel capacitor 2 via the pixel TFT 3 connected to. The pixel TFT 3 holds the electric charge written in the pixel capacitor 2 at the time of selection, during the non-selection period by its high off resistance at the time of non-selection. Then, the pixel TFT 3 writes a new image signal in the pixel capacitor 2 in the next selection. The above is the same as the display method of the conventional TFT active matrix type liquid crystal display device.

Next, the information input function which is an additional function in the liquid crystal display device of the present invention will be specifically described below with reference to FIG. As a main configuration as an information input function, there are a reading unit that reads a signal written in a pixel electrode as a pixel signal through a signal line, and a pixel signal storage unit that stores the pixel signal read by the reading unit. . The sensing circuit 12 which constitutes this reading means is composed of an integration circuit, a current-voltage conversion circuit, or the like, and, contrary to the case of writing the image signal described above, charges written in the pixel capacitance 2 of each pixel are , The switch 9 is sequentially turned on in synchronism with the timing of sequentially selecting the gate line 4, reads out from the data line 5, and leads to the video line 8. The read mode and the normal display mode described above are selectively switched by the mode selector switch 11. Which memory the read pixel signal is to be stored in is selected by the switch 13, and the pixel signal as information data is stored in the first pixel signal memory 14, while in the second pixel signal memory 15. Reference data that has been read in advance is stored, and the contents of these two pixel signal memories are compared and calculated by the comparison circuit 16.

Here, this reference data is, for example, data read out after writing 0 or the minimum video signal, and it is a variation in the characteristics of each pixel TFT 3 and a parasitic in the electric path from the pixel electrode to the readout circuit. It is a noise level signal that includes the effects of capacitance and parasitic resistance, and serves as a comparison signal for the measurement signal.

Next, based on the comparison result by the comparison circuit 16, the pixel signal as the information data is subjected to predetermined data processing such as data conversion to the video signal for driving the liquid crystal in the data processing circuit 17 for display. Generate an output signal for. Then, the generated output signal for display is amplified by the amplifier circuit 1.
Input to 8 and amplify. The amplified display output signal is guided to the video line 8 by switching the mode changeover switch 11 to the c-contact side which is the output mode. This allows
The information data stored in the pixel signal storage means by the information input function can be displayed on the screen by controlling the liquid crystal display device in the normal display mode.

Next, the liquid crystal display device of the present invention having the above structure will be described in more detail with reference to the embodiments shown in FIGS. The liquid crystal display device of the present invention shown in FIG. 2 uses a backlight for liquid crystal display as a light source of an irradiation unit for increasing the off current of the pixel TFT and changing the information written in the pixel electrode. That is, the backlight 21 arranged outside the counter substrate 22 is used not only as the original light source for display of the liquid crystal display device but also on the original document 24 as the object to be read arranged on the opposite side through the liquid crystal display device. It is also used as a light source that emits light. Specifically, as shown in FIG. 2, the reflection from the light from the backlight 21 passes through the counter substrate 22 and the active matrix substrate 23 and is reflected by the original 24 to be read, which is placed outside the active matrix substrate 23. The light RB is used as an irradiation unit, and the reflected light RB is incident on the pixel TFT 3 of the active matrix substrate 23, whereby the pixel TF is obtained.
The off current of T3 is increased to change the information written in the pixel electrode. At that time, the document to be read 2
For the purpose of increasing the intensity of the reflected light from No. 4 and improving the SN ratio at the time of sampling the signal of the pixel capacitance, the backlight intensity may be increased only at the time of reading. For that purpose, it is necessary to adjust the light control circuit of the backlight and provide a light intensity changing means for changing the light intensity.

By the way, the pixel TFT 3 originally has a role of holding the charges written in the pixel capacitor 2. Therefore, a device structure is adopted in which the leakage current, that is, the off-state current of the transistor is reduced. As a typical structure thereof, an LDD (lightly doped dr) is used.
ain) structure and offset structure. In the LDD structure shown in the schematic cross-sectional view of FIG. 4, a gate electrode 47 is partially formed on a TFT active region 45 with a gate insulating film 46 sandwiched therebetween. The active region 45 includes a source region 41 and a channel region. 44 and the drain region 42, and further between the source region 41 and the channel region 44 and between the drain region 42 and the channel region 44, the low concentration impurity implantation region 43.
(Or impurity non-implanted region 43) is formed. These low-concentration impurity-implanted regions 43 (or non-impurity-implanted regions 43) have a function of reducing carrier generation due to a high electric field and reducing off-current by relaxing the electric field strength applied to the drain portion.

Therefore, in the structure shown in FIG.
The backlight 21 provided outside the light source 2 is used as a light source, and the light from the light source passes through the counter substrate 22 and the active matrix substrate 23 and is reflected by the original document 24 to be read placed outside the active matrix substrate 23. When the reflected light RB is incident on the low-concentration impurity-implanted region 43 (or the impurity-non-implanted region 43) of the pixel TFT 3 shown in FIG. 4 of the active matrix substrate 23, photoexcitation causes carrier generation to increase the off-current. as a result,
The electric charge written in the pixel capacitor 2 leaks through the pixel TFT 3, and the electric charge accumulated in the pixel capacitor 2 changes according to the intensity of the reflected light from the read document 24 irradiated on the pixel TFT 3. By reading the electric charge of the pixel capacitor 2 after this fluctuation and comparing the read pixel signal with the above-mentioned reference data, the image of the original from which noise and the like are removed can be fetched as information data. The liquid crystal display device of the present invention has such an information input function.

However, in the liquid crystal display device of the present invention having this information input function, when the off-current of the pixel TFT 3 increases due to the illumination of the pixel electrode by the backlight 21, the display quality during normal image display is improved. The problem of getting worse arises. To solve this problem, a light shielding means for the pixel TFT 3, specifically, a metal layer or a black resin is added on the backlight irradiation side, and the light shielding effect is weakened on the side on which the document 24 to be read is placed. This problem can be solved by providing a light shielding means.

Next, the procedure of capturing image data as the information input function of the present invention will be described below with reference to FIG. First, the mode changeover switch 11 shown in FIG. 1 is switched to the a-contact side to set the normal mode, and the same image signal as information data, preferably the signal having the maximum amplitude among the image signals, is written in all pixels. Next, mode switch 1
1 is switched to the b contact side to enter the image input mode, and the sensing circuit 12 and the video line 8 are connected. next,
The gate driver 6 is operated to scan the gate line 4,
That is, the pixel TFTs 3 connected to the gate line 4 are sequentially switched, the switches 9 connected to the data line 5 are sequentially turned on in synchronism with the switching, and the pixel capacitances 2 whose charges are changed by the light from the irradiation means 2 The potential of is introduced to the sensing circuit 12 via the data line 5, the switch 9 and the video line 8.

By the way, when this series of operations is performed,
The time from writing the image signal in the pixel capacitor 2 to reading it as the pixel signal is longer than the field time from writing the image signal during image display to writing the next image signal. Therefore, it is possible to increase the off-current by injecting light into the pixel TFT 3 described above and to secure the minimum necessary time for changing the pixel signal. In order to further enhance the effect of changing the pixel signal due to the incidence of light on the pixel TFT 3, a waiting time may be provided from the writing of the image signal to each pixel capacitor 2 to the reading thereof.

Next, the sensing circuit 12 samples this potential change at a predetermined timing, integrates it in an integrating circuit, or converts current into voltage in a current-voltage converting circuit. This sampling signal is stored in the first pixel signal memory 14 by selecting the d contact of the switch 13. After the sampling of the signals from all the pixel capacitors 2 is completed, the above-mentioned mode changeover switch 11 is switched to the a-contact side, and the display mode is set. Second pixel signal memory 15
In advance, a sampling signal when a 0 V video signal is input as reference data is stored in advance as a comparison signal, and the pixel signal and the comparison signal as the information data respectively stored in these two pixel signal memories 14 and 15 are stored. Are compared by the comparison circuit 16. This comparison operation may be performed immediately after reading the sampling signal or after a desired time has elapsed after reading the sampling signal.

Next, based on the comparison result by the comparison circuit 16, the data processing circuit 17 performs predetermined data processing on the pixel signal as the information data, for example, noise removal,
Signal level conversion or data conversion to mirror-inverted data is performed to generate a display output signal for driving the liquid crystal. This data processing is performed by the image signal memories 14 and 15
You may implement it when reading data from. Next, the display output signal is amplified by the amplifier circuit 18, the mode changeover switch 11 is switched to the c-contact side which is the output mode, the amplifier circuit 18 and the video line 8 are connected, and the amplified display output is obtained. The signal is input to the video line 8. As a result, the information read from the read document 24 by the information input function as the information data and stored in the pixel signal storage means can be displayed on the screen by controlling the liquid crystal display device in the normal display mode. .

Next, another embodiment of the liquid crystal display device of the present invention will be described below with reference to FIG. This liquid crystal display device uses a light source having a spot diameter corresponding to the size of one or a plurality of pixels as the irradiation means. A light emitting diode, a semiconductor laser, or the like can be used as the light source. Normally, when an image is displayed on a liquid crystal display device, the image is rewritten for each pixel about 50 to 60 times per second according to the frame frequency of the image signal. In the present embodiment, of the rewriting of the image, for example, once every 0.1 seconds, the above-mentioned image reading operation is performed instead of the rewriting of the image by the mode changeover switch 1.
Switch 1 to perform. At that time, the spot light of the pen-shaped light source 31 having the spot light shown in FIG. 3 is supplied to a specific pixel 34 of the liquid crystal panel 32 as shown in a partially enlarged view A.
When irradiating on, the pixel signal of the corresponding pixel TFT 3 is different from the pixel signal of the non-irradiated pixel, so that the above-mentioned pixel signal reading unit can detect which pixel is irradiated with the spot light. it can. Therefore, the irradiation position of the spot light can be displayed on the screen by reading the information data stored in the pixel signal memory without the data processing circuit performing the data processing of the mirror surface inversion.

The spot light can control the size of the light source. Specifically, for example, a pinhole having a variable opening is provided on the optical path through which the light of an LED or a semiconductor laser, which is a light source of spot light, is condensed and emitted by an optical lens. Adjustment is made so that irradiation of a plurality of pixels is performed at once. In that case, when the position of the spot light is displayed, the display becomes large, so that the visibility is improved.

Further, the spot light is effectively used for the pixel TFT3.
As shown in a partially enlarged view A of FIG. 3, a filter 35 that transmits only the spot light in the vicinity of the wavelength of the light source is formed so as to cover the pixel TFT 3, and
The incidence sensitivity can be increased as compared with the case where other ambient light is incident on T3.

The liquid crystal display device described in the above embodiment is a so-called driver monolithic TFT liquid crystal display device, and the liquid crystal drive driver including the gate driver 6, the data driver 7, the drive control unit 10, etc. is made of polycrystalline silicon. It can be formed and integrated with the screen unit 1 on the same substrate.

Further, the mode changeover switch 11, the sensing circuit 12, the switch 13, which has been described in the above embodiment,
First pixel signal memory 14 and second pixel signal memory 1
5, comparison circuit 16, data processing circuit 17, and amplifier 18
Similarly, the same can be formed by using polycrystalline silicon, and can be integrated and integrally formed on the same substrate.

Further, in the above-described embodiment, the example in which light is used as the information changing means for changing the information written in the pixel electrode is disclosed, but the pixel capacity accumulated by means other than light may be changed. Good. For example, as a means other than light, a change in the liquid crystal capacitance due to the narrowing of the space between the substrates due to pressure may be used.

[0056]

According to the above-described liquid crystal display device of the present invention, not only the display but also the reading and display of image data of a document as an information input function, or the pointing operation with an optical pen can be performed, and a word processor, a personal computer. It is useful as an additional function of a display for mobile information terminals.

Moreover, such an additional function can be incorporated without substantially increasing the external dimensions of the liquid crystal display device. That is, since the TFT connected to each pixel of the liquid crystal display device is used as the element used for the information input function, the size can be reduced by the amount of the shared use of the element. Further, it is possible to suppress an increase in manufacturing cost without requiring a new manufacturing process.

In particular, the liquid crystal display device of the present invention can be made into a so-called driver monolithic by integrating and integrally forming a liquid crystal driving driver on an active matrix substrate made of a thin film transistor using polycrystalline silicon.

Further, at least one of the reading means, the pixel signal storing means, the comparing means and the data processing means is provided on the same substrate of the driver monolithic liquid crystal display device.
It is also possible to integrally form one. As a result, each circuit of the liquid crystal display device can be integrated and integrated, so that the liquid crystal display device having an information input function can be further downsized. Further, high-speed display is possible in the liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a liquid crystal display device according to the present invention.

FIG. 2 is a diagram showing an embodiment of a liquid crystal display device according to the present invention.

FIG. 3 is a view showing another embodiment of the liquid crystal display device according to the present invention.

FIG. 4 is a schematic sectional view showing a TFT having a general LDD structure.

FIG. 5 is a circuit diagram showing a conventional liquid crystal display device.

[Explanation of symbols]

1 screen section 2 pixel capacity 3 pixel TFT 4 gate lines 5 data lines 6 gate driver 7 Data driver 8 video lines 9, 13 switch 10 Drive control unit 11 Mode selector switch 12 Sensing circuit 14 First pixel signal memory 15 Second pixel signal memory 16 Comparison circuit 17 Data processing circuit 18 amplifier circuit 21 Backlight 22 Counter substrate 23 Active matrix substrate 24 Original document 31 Pen-shaped light source 32 LCD panel 34 pixels 35 filters 41 Source Area 42 drain region 43 Low-concentration impurity-implanted region or non-impurity-implanted region 44 channel region 45 Active area 46 Gate insulating film 47 Gate electrode 51 Image reading section 52 Image display section 53, 55 TFT 54 Photoelectric conversion element 56 pixel capacity

Continuation of the front page (56) Reference JP-A-8-234906 (JP, A) JP-A-6-309450 (JP, A) JP-A-9-230307 (JP, A) JP-A-5-333369 (JP , A) JP-A-7-325319 (JP, A) JP-A-8-272529 (JP, A) JP-A-5-281516 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G02F 1/1368 G09F 9/35 305 G02F 1/133 530

Claims (11)

(57) [Claims] 1. A pixel electrode, a switching element connected to the pixel electrode, a scanning line for driving the switching element, and a signal line for inputting a signal to the pixel electrode via the switching element. In a liquid crystal display device in which a liquid crystal layer is sandwiched between an active matrix substrate having a matrix array and a counter substrate provided with a counter electrode, the LDD structure in which the switching element is made of polycrystalline silicon.
Composed of a photoexcitable thin film transistor having a structure
A liquid crystal display device having a reading means for reading the information written in the pixel electrode as a pixel signal via the signal line, and a pixel signal storage means for storing the pixel signal read by the reading means. 2. The liquid crystal display device according to claim 1, further comprising an information changing unit that changes the information written in the pixel electrode. 3. A pre-Symbol liquid crystal display device according to claim 1 or claim 2, wherein the liquid crystal driver for driving, which are integrally formed on the active matrix substrate. 4. The liquid crystal display device according to claim 1, wherein at least one of the reading unit and the pixel signal storage unit is integrally formed on the active matrix substrate. 5. A plurality of the pixel signal storage means are provided, and a signal written as reference data in the pixel electrode is stored as a read comparison signal by the read means in at least one of the pixel signal storage means, and the other is stored. 5. The liquid crystal display device according to claim 1, further comprising a comparing unit that compares the pixel signal stored as information data in the pixel signal storage unit with the comparison signal. 6. The liquid crystal display device according to claim 1, further comprising a data processing unit that applies predetermined data processing to the pixel signal read by the reading unit to generate a display output signal. 7. The thin film transistor is a field effect transistor.
7. A field effect transistor, which is a transistor, is provided with an irradiation unit that irradiates light from the outside, and has an information changing unit that changes the information written in the pixel electrode by the irradiation unit. The liquid crystal display device according to claim 1. 8. A reading source installed on the outside of the active matrix substrate, wherein the light source is provided on the outside of the counter substrate, and the light from the light source passes through the counter substrate and the active matrix substrate. The liquid crystal display device according to claim 7, wherein the reflected light reflected by the object is used. 9. The light source in the irradiation means,
9. The liquid crystal display device according to claim 8, further comprising a light intensity changing unit that changes the light intensity of the light source when a display is performed using a light source for liquid crystal display and when the information is changed by the information changing unit. 10. The liquid crystal display device according to claim 8, wherein the data processing unit has a data conversion function of mirror-inversion of information changed by the reflected light. 11. The liquid crystal display device according to claim 7, wherein a light source having a spot diameter corresponding to one or a plurality of pixel sizes is used as the irradiation unit.