JP2001075732A - Optical detection type digitizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical detection type digitizer which can be built in a liquid crystal display panel, eliminates the need for a connection cord, and does not lower the display function by supplying a 1st and a 2nd potential and varying the potential of a 1st scanning line according to light irradiation and nonirradaition. SOLUTION: Row scanning lines Y1 to Y5 are applied with a pulsating potential in line sequence by a pulse voltage generating circuit 1. Row scanning lines Z1 to Z5 are applied with a constant potential. The voltages of column scanning lines X1 to X5 are detected by a detecting circuit 2. The detecting circuit 2 receives each potential showing whether or not cells Cij connected to row scanning lines Yi are irradiated with light sequentially by the row scanning lines Yi through the column scanning lines X1 to X5 and outputs it to outside the optical detection type digitizer. According to the potential outputted from the optical detection type digitizer, the light irradiation positions of cells by a light pen 3 are measured. According to the measurement results, the liquid crystal display cells of a liquid crystal display panel are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light detection type digitizer for detecting a position using light as a medium, and more particularly to a light detection type digitizer which can be incorporated in a liquid crystal display panel.

[0002]

FIG. 13 is a diagram showing a simple structure of a conventional display-integrated digitizer. In the figure, 100,
101 is a transparent electrode, 102 is an input pen, 103
Denotes a liquid crystal panel. The display-integrated digitizer in FIG. 13 is incorporated in, for example, an electronic organizer and functions as a position detector for detecting an input position by an input pen. The display-integrated digitizer has transparent electrodes 100, 10
Two transparent films having a gap having a value of 1 are provided on the display-only element of the liquid crystal panel 103. The display-integrated digitizer detects that pressure is applied to the transparent film by the input pen 102, and that the voltage at the outer peripheral portion of the transparent film changes at a point where the two transparent films come into contact with each other, and measures the position. , The pressure application point is detected.

[0003]

However, in the conventional pressure-sensitive display-integrated digitizer, the transparent film must be made transparent but conductive, so that the visible light transmittance is reduced. This causes a problem that a display screen for displaying characters and the like becomes dark. In particular, in a reflection type liquid crystal display device that has been receiving attention in recent years, the transmittance is reduced by about 20 to 30%, and a problem that a display screen is extremely difficult to see occurs.

As another digitizer, there has been developed a type in which a pen input panel which does not deteriorate the display function is integrally formed. In this type, for example, an electrostatic coupling between the pen input panel and the input pen is used. Therefore, there is a problem that a code for connecting between the input pen and the pen input panel is separately required.

The present invention has been made to solve the above problems, and can be incorporated in a liquid crystal display panel, and does not require a code for connecting between an input pen and a pen input panel, and It is an object of the present invention to obtain a light detection type digitizer that does not deteriorate the display function.

[0006]

A light detection type digitizer according to the present invention is supplied with a first scanning line, a first potential and a second potential, is connected to the first scanning line, and is connected to the first scanning line. A cell for changing the potential of the first scanning line according to each of irradiation and non-light irradiation. A second scanning line connected to the cell and supplying a first potential to the cell; and a third scanning line connected to the cell and supplying a second potential to the cell. In addition, the first scanning line has a third potential in advance, and when the cell is irradiated with light, the cell:
The potential of the first scan line is changed from the third potential to the second potential, and when the cell is not irradiated with light, the cell holds the potential of the first scan line at the third potential. Also, the cell is
A first thin film transistor having one end connected to the first scan line and the other end connected to a third scan line; one end connected to a gate electrode of the first thin film transistor; and the other end connected to a second scan line And a first photodetector connected to the first photodetector. The cell has one end connected to the third scanning line,
The first light detecting element includes a first resistance element having one end connected to the other end. In addition, the semiconductor device has an opening on the first light sensing element and includes a first metal film provided on the first resistance element. Further, the first light detecting element is
It has an amorphous silicon film. In addition, a second metal film is provided below the amorphous silicon film of the first light sensing element. Further, the first thin film transistor is a polycrystalline silicon thin film transistor. The first scanning line has a fourth potential in advance, and when the cell is irradiated with light, the cell holds the potential of the first scanning line at the fourth potential and causes the cell to emit no light. At the time of irradiation, the potential of the first scan line is changed from the fourth potential to the first potential. The cell has a second end connected to the first scan line and the other end connected to the second scan line.
A second photodetector having one end connected to a gate electrode of the second thin film transistor and the other end connected to a second scan line, and one end connected to a third scan line. And a second resistance element having the other end connected to one end of the light detection element. In addition, an opening is provided on the second photodetector, and a third metal film provided on the second resistor is provided. Further, the second light detecting element has an amorphous silicon film. Further, a fourth metal film is provided below the amorphous silicon film of the second photodetector. Further, the second thin film transistor is a polycrystalline silicon thin film transistor. Further, N first scanning lines, second scanning lines, and third scanning lines are provided, and
Are provided so as to intersect the N first scanning lines,
Each third scanning line is provided along each second scanning line so as to intersect the N first scanning lines, and the first scanning line, the second scanning line, and the third scanning line are provided. Are connected in a matrix. In addition, N second
A pulse voltage generating circuit connected to each of the scan lines and sequentially supplying a first potential to each of the second scan lines;
Detecting circuit that receives each potential of N first scanning lines based on each cell connected to the second scanning line to which the first potential is supplied by the pulse voltage generation circuit. It is provided with. The first scan line, the second scan line, the third scan line, the cell, the pulse voltage generation circuit, and the detection circuit are provided on the thin film transistor array substrate. Further, the cell is provided with a liquid crystal capacitance, a parasitic capacitance, and a thin film transistor which constitute a display function.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 The digitizer according to the present invention is of a light detection type. Since a liquid crystal display panel (LCD) generally has a configuration in which liquid crystal display cells are arranged in a matrix, in order to incorporate a photodetection digitizer into the liquid crystal display panel, the photodetection elements of the photodetection digitizer are also arranged in a matrix. The arrangement to arrange them is good. A light detection type digitizer according to an embodiment of the present invention has light detection elements incorporated in a liquid crystal display panel and arranged in a matrix.

FIG. 1 is a diagram showing a configuration of a light detection type digitizer according to a first embodiment of the present invention. In the figure, 1
Is a pulse voltage generation circuit, 2 is a detection circuit, and 3 is a light pen for input. The light pen 3 irradiates light to detect the position indicated by the pen. Xi (i = 1 to
5) is a column scanning line, Yi (i = 1 to 5) and Zi (i =
1 to 5) are row scanning lines, Cij (i = 1 to 5, j
= 1 to 5) are cells. The column scanning lines X1 to X5 intersect with the row scanning lines Y1 to Y5 and the row scanning lines Z1 to Z5, respectively. The cell Cij is an area that is in contact with the row scanning line Yi, the row scanning line Zi, and the column scanning line Xj. Cell Ci
j is a light detecting element Sij (i = 1 to 5, j = 1 to 5)
And thin film transistor Tij (i = 1 to 5, j = 1 to 5)
Are provided. Each scanning line is formed of a metal wiring. In this embodiment, the light detection type digitizer is a reflection type thin film transistor liquid crystal display (T
On a thin film transistor array substrate (not shown) of an FT-LCD, they are formed in a matrix as shown in FIG. A liquid crystal display panel of a thin film transistor liquid crystal display has an opposite substrate and a thin film transistor array substrate, and liquid crystal exists between the two substrates. Thin film transistor array substrate, thin film transistor, wiring, reflective electrode, etc.
A sheet having a display function and a sheet having a light detection type digitizer having a scanning line, a light detection element (sensor), and the like are laminated and formed.

Pulse-like potentials are applied line-sequentially to the row scanning lines Y1 to Y5 by the pulse voltage generation circuit 1. A constant potential is applied to the row scanning lines Z1 to Z5.
The voltages of the column scanning lines X1 to X5 are detected by the detection circuit 2. The detection circuit 2 sequentially receives, for each row scanning line Yi, each potential indicating light irradiation or light non-irradiation on the cell Cij connected to the row scanning line Yi via the column scanning lines X1 to X5, Output to the outside of the light detection type digitizer. Based on each potential output from the light detection type digitizer, the light irradiation position of the cell by the light pen 3 is measured. The corresponding liquid crystal display cell of the liquid crystal display panel is controlled based on the measurement result.

FIG. 2 is a sectional view showing the structure of the cell Cij of the photo-detecting digitizer of FIG. In the figure, 4
Is an insulating substrate, 5 is a polycrystalline silicon film crystallized on the insulating substrate 4 by laser, 6 is a gate insulating film made of a SiO2 film, 7 is a gate electrode made of a metal film, and 8 is polycrystalline silicon. Source / drain regions in which phosphorus ions are implanted into the film, 9 is an interlayer insulating film made of a SiO2 film, 10 is a drive voltage wiring, 11 is a ground wiring, 12 is an amorphous silicon film, 13 is a metal film, and 14 is amorphous An electrode forming portion in which phosphorus ions are implanted into the porous silicon film 12, 15 is a metal film, 16 is an insulating film made of SiN, and 17 is a metal film. S indicates a sensor, R indicates a reference resistance, and T indicates a thin film transistor. Similar to the sensor S, the reference resistance R is composed of an amorphous silicon film, a metal film, and an electrode forming portion in which phosphorus ions are implanted into the amorphous silicon film. With the amorphous silicon film 12 of the sensor, a light-detecting digitizer that receives light having a wavelength in the range from infrared light to visible light can be easily formed using a thin film transistor process.

The polycrystalline thin film transistor T comprises a polycrystalline silicon film 5, a gate insulating film 6, a gate electrode 7,
It is composed of a drain region 8. The interlayer insulating film 9 is formed so as to cover the thin film transistor T. When the gate electrode 7 of the thin film transistor T is formed, the drive voltage wiring 10 and the ground wiring 11 are formed at the same time. The amorphous silicon film 12 is formed on the interlayer insulating film 9 and at a portion below the interlayer insulating film 9 where the thin film transistor T is not formed. Since the capacity of the thin film transistor can be made small by the polycrystalline thin film transistor T, a light sensing type digitizer with high response speed can be formed. A metal film 13 is formed in advance immediately below the amorphous silicon film 12 via the interlayer insulating film 9 when the gate electrode 7 of the thin film transistor T is formed. An electrode forming portion 14 is formed in the amorphous silicon film 12 by ion implantation. In the electrode forming portion of the thin film transistor T, a contact hole (not shown) penetrating the upper interlayer insulating film 9 and the gate insulating film 6 is formed. A similar contact hole is formed on the drive voltage wiring 10 and the ground wiring 11 at a place where a metal wiring is required. In order to connect the thin film transistor T to the amorphous silicon film 12, the drive voltage wiring 10, and the ground wiring 11, a metal film 15 connecting the above-described contact hole and the ion-implanted portion of the amorphous silicon film 12 is formed. An insulating film 16 is formed on the above structure. A contact hole is formed in a portion where electrode extraction is required. The metal film 17 is formed on the amorphous silicon thin film which becomes the reference resistance R.

FIG. 3 is a diagram showing a detailed configuration of the light detection type digitizer of FIG. In the figure, Cij (i = 1
To 5, j = 1 to 5) are the same ones repeatedly arranged. The ground wiring 11 in FIG. 2 is maintained at the voltage Vb, and the drive voltage wiring 10 is applied with a pulse by the pulse voltage generation circuit 1 to have the normal potential Vb and the pulse applied potential Va. The detection circuit 2 detects the voltage of the output wiring (column scanning lines X1 to X5). Each cell Cij is provided with a sensor Sij, a reference resistor Rij, and an N-type thin film transistor Tij. Column scanning lines X1 to X5
Are respectively connected to switch elements RSW1 to RSW5. Switch elements RSW1 to RSW5
A power supply potential (not shown) is externally applied to both ends of the wiring to which is connected. The source of the thin film transistor T is connected to the row scanning line Z, and the drain is connected to the column scanning line X. The N-type thin film transistor T can constitute a light detection type digitizer with less malfunction.

Hereinafter, the operation of the light detection type digitizer will be described for the case where light is radiated to the area of the cell C34 in FIG. FIG. 4 is a timing chart showing the operation of the light detection type digitizer. The potentials of the row scanning lines and the column scanning lines are shown. The arrow in the figure indicates the potential Vb
Indicates that the potential Vc is relatively higher than the potential Vc.
This shows that the potential Va is relatively higher than the potential Vb. The pulse voltage Va is applied to the row scanning lines Y1 to Y5 line by line by the pulse voltage generation circuit 1.
A constant potential Vb is applied to each of the row scanning lines Z1 to Z5. The column scanning lines X1 to X5 have a very short period in the beginning of the period in which the pulse is applied to the row scanning lines Y1 to Y5.
The potentials Vc are charged by the switch elements RSW1 to RSW5, respectively. Switch elements RSW1 to RSW5
Turns on or off at once. Vrst is a potential applied from outside the device, and N works as switch elements RSW1 to RSW5 connected to the column scanning lines X1 to X5.
Is supplied to the gate voltage of the thin film transistor. That is, when Vrst is at the H level, the column scanning lines X1 to X5
The potential is reset to the potential Vc connected via the switch elements RSW1 to RSW5. When a pulse of the potential Va is applied to the row scanning line Y3 by the pulse voltage generation circuit 1, the sensor S3j (j = 1 to 5) in the cell C3j (j = 1 to 5) and the reference resistor R3j (j = 1 ~ 5)
A voltage having a height of (Va-Vb) is applied to the components connected in series. Therefore, the gate electrode Vg of the thin film transistor T3j (j = 1 to 5) in the cell C3j (j = 1 to 5)
The potential Vg3j (j = 1 to 5) is expressed as follows: Vg = Vb + (Va−Vb) × Rr / (Rs + Rr) Rr indicates the resistance value of the reference resistor Rij, and Rs indicates the resistance value of the sensor Sij. When light is irradiated on the cell, Rs becomes small. The value of Rs at this time is Rs
h. At the time of light irradiation, Vg becomes thin film transistor Tij
Va, Vb, R such that the threshold voltage Vth becomes higher than
By setting sh, Rr, and Vth, the potentials held on the column scanning lines X1 to X5 change until they reach the same potential as Vb.

In a row scanning line other than the row scanning line Y3, no voltage is applied to a line in which the sensor Sij and the reference resistor Rij are connected in series. Therefore, cell C3j (j = 1 to
In cells other than 5), Vgij remains at Vb, so that no current flows through the thin film transistor. Row scan line Y
As shown in FIG. 4, the voltages of the column scanning lines X1 to X5 during the period in which the pulse is applied (potential Va) to 3 are the potential Vb for the column scanning line X4 and the potential Vc for the other column scanning lines. . Each potential of these column scanning lines X1 to X5 is detected by the detection circuit 2
And cell C3j (j = 1) from the detection result.
It is determined whether or not there is a light irradiation on (5). In this case, it is detected that light is irradiated near the sensor S34, that is, that the light irradiation position irradiated with the light pen 3 is C34. When the pulse voltage Va is applied line-sequentially to the row scanning lines Y1 to Y5 by the pulse voltage generation circuit 1,
The presence or absence of light irradiation on all cells can be determined.

As can be seen from the above equation, the light detection threshold is
It changes according to the value of (Va−Vb) and the sensor size, that is, the resistance value (Rs) when no light is irradiated. By making the value of Va variable, the detection threshold can be adjusted on the spot.
As described above, the light detection type digitizer according to the first embodiment is incorporated in a liquid crystal display panel, and a matrix light detection element is provided according to the liquid crystal display cell.
A code for connecting the input pen to the pen input panel is not required, and there is no problem on the display screen due to a decrease in transmittance as in the pressure-sensitive type digitizer-integrated display device, and the light irradiation position of the light pen can be detected. In addition, between light irradiation and non-light irradiation, the potential at the column scanning line is binarized based on each cell, and there is an effect that the noise resistance is excellent. In addition, the metal film 13 provided below the sensor can block irregularly reflected light from below the light-detecting digitizer, thereby reducing the variation in detection sensitivity. Further, since the sensor S and the reference resistor R are formed of the same material and have the same configuration, the ratio between the resistance of the sensor S and the resistance of the reference resistor R when light is not irradiated can be fixed relatively easily.

Embodiment 2 FIG. 5 is a diagram showing a detailed configuration of a light detection type digitizer according to Embodiment 2 of the present invention. The difference from the first embodiment is that the configuration of FIG. 5 has no reference resistance in the cell. Other configurations are the same as those in FIG. 3 of the first embodiment. The configuration shown in FIG.
As in the first embodiment, the column scanning lines X1 to X5
The light irradiation position can be detected. In this case, the time required for Vg to reach Vth of the thin film transistor T changes depending on light irradiation and non-light irradiation, and consequently, the time during which the transistor is turned on differs. The potential of the gate electrode is temporally
It changes from the initial value to the final potential according to a time constant determined by the sensor resistance and the gate capacitance of the thin film transistor T.

The pulse voltage Va is applied to the row scanning lines Y1 to Y5 line by line by the pulse voltage generation circuit 1. A constant potential Vb is applied to the row scanning lines Z1 to Z5. The sensor resistance at the time of light irradiation or no light irradiation is Rs,
Assuming that the gate capacitance of the thin film transistor T is Ct, the potential Vg of the gate electrode of the thin film transistor T after a time t from the start of pulse application is Vg (t) = Va− (Va−V
b) × exp (−t / Rs / Ct) The sensor resistance differs between light irradiation and non-light irradiation, and the resistance value during light irradiation is smaller. Assuming that the time from the start of application of the pulse (Va) for determining light irradiation and non-light irradiation is tj1,
At the time of light irradiation, Vg (tj1)> Vth, and at the time of light non-irradiation, Vg (tj2) <Vth since the value of Vg of the thin film transistor T should be less than the threshold voltage after time tj2 from the end of pulse application. , So that tj
By setting 1, tj2, light irradiation and light non-irradiation can be determined according to the light intensity. If tj1 is made longer, it is possible to detect even weak light irradiation.

Further, the value of (Va-Vb), tj1, tj
The threshold of light detection can be adjusted by the value of 2 and the sensor size. FIG. 6 is a diagram illustrating the dependence of the determination time tj1 of the light detection threshold value and the value of Va−Vb (= Vdrv) in this embodiment. Tj in FIG. 6 is tj1. The case where the sensor size is 20 microns × 10 microns is shown. It can be seen from the determination time and the value of (Va-Vb) that the light detection threshold can be adjusted. The light intensity in FIG. 6 is a light detection threshold. FIG. 6 shows the relationship between Vdrv, tj1 and the light detection threshold when the threshold value of the thin film transistor T is 2.2V. In the first embodiment, (Va
In addition to the value of −Vb), the values of tj1 and tj2, and the sensor size, the threshold value of light detection can be adjusted by the relationship of the reference resistance size. Since the light detection type digitizer of this embodiment is configured as described above, the same effects as those of the first embodiment can be obtained except for the effect relating to the resistance ratio. Further, the area can be reduced as compared with the configuration of the first embodiment.

Embodiment 3 In this embodiment, the sensor S11 of the light detection type digitizer according to the second embodiment is used.
ＳS55 are shielded from light to perform position detection. For example, the area indicated by the pen in FIG. 1 is shielded from light using a light-shielding pen, and the resistance of the other sensors is reduced without reducing only the resistance of the corresponding sensor S34. As a result, only the thin film transistor T of the cell C to which light is not irradiated is not turned on, and a place to which light is not irradiated is detected. FIG.
FIG. 13 is a timing chart of the operation of the light detection type digitizer according to Embodiment 3 of the present invention. Except that the output is inverted, it is the same as the light pen method in the above-described embodiment. FIG. 7 shows that since the cell C34 is shielded from light, the potential of the column scanning line X4 connected to the cell C34 is different from the other column scanning lines.

In the case of the light-shielding pen method, since light in a normal environment is used, it is necessary to lower the light detection threshold.
Therefore, the determination times tj1 and tj2 are increased, and the sensor resistance is reduced. Since the light detection type digitizer of this embodiment is configured as described above, the same effects as those of the first and second embodiments can be obtained.

Embodiment 4 FIG. In this embodiment, like the sensor S and the reference resistor R in the light-detecting digitizer of the first embodiment, the thin film transistor T also includes the amorphous silicon film 12 and the electrode forming section 14. FIG.
FIG. 14 is a cross-sectional view showing a structure of a cell Cij of a photodetection digitizer according to Embodiment 4 of the present invention. Cell Ci
j are arranged in a matrix, as in the first embodiment. The operation of detecting the light irradiation position of the light pen 3 is the same as in the first embodiment.

In the figure, reference numeral 18 denotes a gate electrode made of a metal film, and 19 denotes an insulating film. Other reference numerals are the same as or correspond to those of the configuration shown in the first embodiment.
A gate electrode 18 made of a metal film is formed on the transparent insulating substrate 4. A gate insulating film 6 made of SiN is formed thereon. An amorphous silicon film 12 (channel of a thin film transistor) is formed thereon. Ions (phosphorus) are implanted into the electrode formation portion 14 of the amorphous silicon film 12. An insulating film 19 is formed on the amorphous silicon film 12, and a contact hole is formed in each element (S, T, R) in a metal film 15 or in a necessary place. Then, an insulating film 16 made of SiN is formed on the upper layer of the above structure, and a metal film 17 is formed on the uppermost layer while leaving an opening of the sensor S. The electrode forming part 14
Source / drain. The light detection type digitizer according to this embodiment has the same effects as those of the first embodiment. Further, like the sensor S and the reference resistor R, the thin film transistor T is also composed of the amorphous silicon 12 and the electrode forming part 14, so that the number of masks in the manufacturing process is reduced as compared with the first embodiment, and the cost is reduced. Can be realized.

Embodiment 5 FIG. 9 is a diagram showing a configuration of a cell Cij of a light detection type digitizer according to Embodiment 5 of the present invention. FIG. 10 is a timing chart of the operation of the light detection type digitizer according to the fifth embodiment. Although the thin film transistor T of the light detection type digitizer according to the other embodiments described above is an N-type polycrystalline silicon thin film transistor, in this embodiment, the thin film transistor T is formed of a P-type polycrystalline silicon thin film transistor. In this case, Vc is at the L level. In the other embodiment described above, Vc is at the H level. The light irradiation reduces the resistance of the sensor S, and the drive voltage causes the voltage Vg of the gate electrode of the thin film transistor T to exceed Vth.
Therefore, the thin film transistor T does not turn on. At this time, the potential of the output wiring is kept at the potential of Vc. At the time of non-irradiation, the voltage Vg of the gate electrode of the thin film transistor T remains at Vth or less of the thin film transistor T, so that the thin film transistor T is turned on. At this time, the potential of Va at the source electrode of the thin film transistor T is transferred to the output wiring. The light detection type digitizer is provided in a matrix as shown in FIG. In this embodiment, different from the first embodiment, the conductivity of the thin film transistor T is different, so that the ions for forming the source / drain regions 8 in FIG. 2 are different, but other structures are shown in FIG. The structure is the same as The light detection type digitizer according to this embodiment has the same effects as those of the first embodiment. In FIG. 9, the reference resistor R and the row scanning line Z are removed, and the configuration of the cell C including only the thin film transistor T and the sensor S has a function as a light detection type digitizer.

Embodiment 6 FIG. FIG. 11 is a cross-sectional view showing a structure of a cell Cij of a photodetection digitizer according to Embodiment 6 of the present invention. The cells Cij are arranged in a matrix, as in the first embodiment. The difference from the first embodiment is that, as shown in FIG.
And the reference resistor R have a laminated structure. The operation of the light detection type digitizer is the same as that of the first embodiment.

On the insulating substrate 4, a laser-crystallized polycrystalline silicon film 5, a gate insulating film 6 made of a SiO 2 film, a gate electrode 7 made of a metal film, a polycrystalline silicon film 5
To form a polycrystalline thin film transistor T comprising source / drain regions 8 into which phosphorus ions have been implanted. An interlayer insulating film 9 made of a SiO2 film is formed so as to cover the thin film transistor T. When the gate electrode 7 of the thin film transistor T is formed, the drive voltage wiring 10 and the ground wiring 11 are simultaneously formed.
To form

At the place where the interlayer insulating film 9 is removed, and
The amorphous silicon film 12 is formed at a position where the metal layer 13 is provided in advance. ITO on the amorphous silicon film 12
Is formed. Thin film transistor T
A contact hole is formed through the interlayer insulating film 9 and the gate insulating film 6 above the electrode forming portion. Similar contact holes are formed on the drive voltage wiring 10 and the ground wiring 11. In order to connect the thin film transistor T to the transparent electrode 20, the lower electrode 13 of the amorphous silicon film 12, the drive voltage wiring 10, and the ground wiring 11,
A metal film 15 connecting the contact holes is formed. An insulating film 16 made of SiN is formed on the above structure. A contact hole is formed in a portion where electrode extraction is required. The metal film 17 is formed on the upper part except for the part to be the sensor S. The light detection type digitizer according to this embodiment has the same effects as those of the first embodiment. Furthermore,
Since the sensor S is formed with a laminated structure (the amorphous silicon film 12 and the transparent electrode 20), the resistance value is reduced and the light sensitivity is increased as compared with the first embodiment, so that the response speed is high even with weak light. Is obtained.

Embodiment 7 FIG. 12 is a diagram showing a configuration of a cell Cij of a photodetection type digitizer according to Embodiment 7 of the present invention. The cells Cij are arranged in a matrix as in the first embodiment, but are configured to have both a function as a TFT-LCD and a function as a digitizer. The wirings of Pj and Qi are a data line and a gate wiring related to the display function, respectively. Similarly, the thin film transistor TDij is a transistor related to a display function. The Zi wiring is a common wiring having a display function and a digitizer function. Clc is a liquid crystal capacitance, and Cs is a parasitic capacitance. The substrate having this configuration and the counter substrate of the TFT-LCD are attached so as to sandwich the liquid crystal, thereby providing a display function. The operation of the light detection type digitizer is the same as that of the first embodiment, and the display function in the cell is operated according to the detected light irradiation position. The light detection type digitizer of this embodiment has the same effect as that of the first embodiment, and furthermore, since the two functions are configured on one substrate, the effect of not reducing the brightness of the display is also obtained. is there. Also, by forming the two functions on the same substrate, a manufacturing process of a sheet bonding and a mask can be performed, as compared with a case where separate substrates are provided with the respective functions and bonded together as in other embodiments. The number can be reduced, and wiring can also be used, so that the manufacturing cost can be reduced.

[0028]

As described above, according to the present invention, a light detection type which can be incorporated in a liquid crystal display panel, does not require a cord for connecting between an input pen and a pen input panel, and does not deteriorate the display function. Digitizer can be obtained.

Further, the potential of the column scanning line is binarized based on each cell between light irradiation and light non-irradiation, so that a light detection type digitizer excellent in noise resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a light detection type digitizer according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure of a cell Cij of the photodetection digitizer of FIG.

FIG. 3 is a diagram showing a detailed configuration of the light detection type digitizer of FIG. 1;

FIG. 4 is a timing chart showing the operation of the light detection type digitizer.

FIG. 5 is a diagram showing a detailed configuration of a light detection type digitizer according to a second embodiment of the present invention.

FIG. 6 is a diagram showing the dependence of the light detection threshold value determination time tj1 and the value of Va−Vb (= Vdrv) in the second embodiment of the present invention.

FIG. 7 is a timing chart of the operation of the light detection type digitizer according to Embodiment 3 of the present invention.

FIG. 8 is a cross-sectional view showing a structure of a cell Cij of a photodetection digitizer according to Embodiment 4 of the present invention.

FIG. 9 is a diagram showing a configuration of a cell Cij of a photodetection digitizer according to Embodiment 5 of the present invention.

FIG. 10 is a timing chart of the operation of the light detection type digitizer according to the fifth embodiment.

FIG. 11 is a cross-sectional view illustrating a structure of a cell Cij of a photodetection digitizer according to Embodiment 6 of the present invention.

FIG. 12 is a diagram showing a configuration of a cell Cij of a photodetection type digitizer according to Embodiment 7 of the present invention.

FIG. 13 is a diagram showing a simple configuration of a conventional display-integrated digitizer.

[Explanation of symbols]

1 pulse voltage generation circuit, 2 detection circuit, 3 light pen for input, X1 to X5 column scanning lines, Y1 to Y5
Row scan line, Z1-Z5 row scan line, S sensor,
R reference resistance, T thin film transistor, RSW1
~ RSW5 switch element, C cell, 12 amorphous silicon film, 13 metal film, 17 metal film.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihiko Iwata 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Akihiro Suzuki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 F term (reference) 5B068 AA01 AA11 AA22 BB18 BC03 BC07 BC13 BD02 BD09 BE08 5B087 AA00 AB04 AE00 CC02 CC12 CC16 CC26 CC33 DG02 5F049 MB05 MB12 NA04 NB10 SE02 SZ10 SZ12 TA20 UA01 UA20

Claims (19)

[Claims] 1. A first scanning line, a first potential and a second potential are supplied, connected to the first scanning line, and each of light irradiation and light non-irradiation is provided.
And a cell for changing the potential of the first scanning line. 2. A second scanning line connected to the cell and supplying the first potential to the cell, and a third scanning connected to the cell and supplying the second potential to the cell. 2. The apparatus according to claim 1, further comprising a wire.
The light-detecting digitizer described. 3. The first scanning line has a third potential in advance, and when the cell is irradiated with light, the cell scans the first line.
The potential of the scanning line is changed from the third potential to the second potential, and when the cell is not irradiated with light, the cell changes the potential of the first scanning line to the third potential. 3. The light-detecting digitizer according to claim 2, wherein 4. The cell has a first thin film transistor having one end connected to the first scanning line and the other end connected to the third scanning line, and one end connected to a gate electrode of the first thin film transistor. And a first light detecting element having the other end connected to the second scanning line. 5. The cell includes a first resistive element having one end connected to the third scan line and the other end connected to the one end of the first light sensing element. The light-sensing digitizer according to claim 4. 6. The light according to claim 5, further comprising an opening on the first light sensing element, and a first metal film provided on the first resistance element. Detection type digitizer. 7. The light-sensing type digitizer according to claim 4, wherein said first light-sensing element has an amorphous silicon film. 8. The light-sensing digitizer according to claim 7, wherein a second metal film is provided under the amorphous silicon film of the first light-sensing element. 9. The digitizer according to claim 4, wherein the first thin film transistor is a polycrystalline silicon thin film transistor. 10. The first scanning line has a fourth potential in advance, and when the cell is irradiated with light, the cell is connected to the first scanning line.
Holding the potential of the scanning line at the fourth potential, and changing the potential of the first scanning line from the fourth potential to the first potential when the cell is not irradiated with light. 3. The digitizer according to claim 2, wherein the digitizer is a light-sensitive digitizer. 11. The second cell having one end connected to the first scanning line and the other end connected to the second scanning line.
A thin film transistor, a second light sensing element having one end connected to the gate electrode of the second thin film transistor, and the other end connected to the second scanning line, and one end connected to the third scanning line. 11. The light detection type digitizer according to claim 10, further comprising a second resistance element having the other end connected to the one end of the second light detection element. 12. The light according to claim 11, further comprising an opening on said second light sensing element and a third metal film provided on said second resistive element. Detection type digitizer. 13. The digitizer according to claim 11, wherein the second photodetector has an amorphous silicon film. 14. The digitizer according to claim 13, wherein a fourth metal film is provided below the amorphous silicon film of the second photodetector. 15. The digitizer according to claim 11, wherein the second thin film transistor is a polycrystalline silicon thin film transistor. 16. The first scanning line, the second scanning line, and the third scanning line are each provided with N lines, and each of the second scanning lines is provided with the N lines of the first scanning line. Each third scanning line is provided along each of the second scanning lines,
The cells provided so as to intersect with the N first scanning lines and connected to the first scanning line, the second scanning line, and the third scanning line are arranged in a matrix. The photodetection type digitizer according to any one of claims 2 to 15, wherein a plurality of the digitizers are provided. 17. A pulse voltage generation circuit connected to the N second scanning lines and sequentially supplying the first potential to each of the second scanning lines; Of the N first scanning lines based on each of the cells connected to the second scanning line to which the first potential is supplied by the pulse voltage generation circuit. 17. The light detection type digitizer according to claim 16, further comprising a detection circuit for receiving each potential. 18. The first scanning line, the second scanning line, the third scanning line, the cell, the pulse voltage generation circuit, and the detection circuit are respectively provided on a thin film transistor array substrate. 18. The method of claim 17, wherein
The light-detecting digitizer described. 19. The light-sensing type digitizer according to claim 1, wherein the cell is provided with a liquid crystal capacitance, a parasitic capacitance, and a thin film transistor which constitute a display function.