JP5112260B2 - Touch panel - Google Patents

Description

  The present invention relates to a display device with a touch panel, and more particularly, to a display device with a touch panel having a capacitive coupling type touch panel function realizing high transmittance.

In recent years, touch screen technology supporting a “human friendly” graphical user interface has become important in the spread of mobile devices.
As this touch panel technology, a capacitive bonding type touch panel is known, and a general capacitive bonding type touch panel is provided with a touch panel substrate in which a conductive coating (transparent conductive film) is applied on the surface of a glass substrate. The position is detected by touching the finger here.
There is also known a liquid crystal display panel with a touch panel that performs an operation corresponding to a menu by attaching the touch panel substrate to the surface of the liquid crystal display panel and touching a menu screen displayed on the liquid crystal display panel with a finger. (See Patent Document 1 below)

As prior art documents related to the invention of the present application, there are the following.
JP 2006-146895 A

In the liquid crystal display panel with a touch panel described in Patent Document 1 described above, an AC signal is applied from the four corners of the touch panel coated with a transparent conductive film, and the current flowing through the finger touching the touch panel is detected to detect coordinates. The current is detected by detecting the voltage across the current detection resistor installed at the four corners of the touch panel and converting it to a current.
However, the liquid crystal display panel with a touch panel described in Patent Document 1 described above has the following problems.
(1) In order to secure the current flowing through the finger touching the touch panel, it is necessary to increase the thickness of the transparent conductive film to reduce the resistance. Therefore, the transmittance of the touch panel is lowered.
(2) Four sets of circuits are required corresponding to the four corners. That is, the circuit configuration is complicated because four sets of each of the current detection circuit, noise filter, and sample hold are required.
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a display device with a touch panel that does not reduce the light transmittance and reduces the cost. There is.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
(1) A display device with a touch panel having a substrate having a transparent conductive film having a lattice pattern on a surface on the observer side, wherein the transparent conductive film is used as a transparent electrode of a capacitive touch panel. A position detection pulse voltage generation circuit for inputting a position detection pulse voltage, and a coordinate position calculation circuit for calculating a touch position of the observer's finger on the conductive member, The position detection pulse voltage generation circuit supplies a pulse voltage for position detection to each of the four corners of the transparent conductive film at different timings, and the coordinate position calculation circuit includes: When a pulse voltage for position detection is supplied to one of the four corners of the transparent conductive film, based on the voltage output from the corner on the same diagonal as the corner to which the pulse voltage is supplied, the observer's The conduction of the finger It calculates a touch position on the member.
(2) In (1), the transparent conductive film has at least one island-shaped transparent conductive film inside the lattice pattern, and the at least one island-shaped transparent conductive film is an arbitrary point. And is electrically connected to the grid pattern.
(3) In (2), the at least one island-shaped transparent conductive film is a single rectangular transparent conductive film, and the one rectangular transparent conductive film is an arbitrary point. It is electrically connected to any one of the four grid patterns.
(4) In (2), the at least one island-shaped transparent conductive film is four triangular transparent conductive films, and each of the four triangular transparent conductive films is an arbitrary point. Thus, the four grid patterns are electrically connected to different grid patterns.

(5) In (1) to (4), two corners on one diagonal of the transparent conductive film are corner A and corner B, and two corners on the other diagonal of the transparent conductive film are corner C and corner D. When the coordinate position calculation circuit supplies a pulse voltage for position detection to the corner A of the transparent conductive film, a time A when the voltage output from the corner B becomes a predetermined voltage, and the transparent When a pulse voltage for position detection is supplied to the corner B of the conductive film, the time difference (A−B) from the time B when the voltage output from the corner A becomes a predetermined voltage, and the transparent conductive film When the position detection pulse voltage is supplied to the corner C, the time C when the voltage output from the corner D becomes a predetermined voltage, and the position detection pulse voltage is supplied to the corner D of the transparent conductive film. Time difference (C−D) from time D when the voltage output from corner C becomes a predetermined voltage Based calculates a touch position to the conductive member of the finger of the observer.
(6) In (5), the pulse voltage for position detection supplied to the corner A or the corner C of the transparent conductive film is a pulse voltage that changes from the first voltage level to the second voltage level, and the transparent conductive film The position detection pulse voltage supplied to the corner B or the corner D of the film is a pulse voltage that changes from the second voltage level to the first voltage level.
(7) In (5) or (6), the coordinate position calculation circuit has an integration circuit, and the integration circuit integrates a predetermined current during the time A or the time C, and the time B or By discharging a predetermined current during the time D, a voltage corresponding to the time difference (A−B) or the time difference (C−D) is output.
(8) In (7), the integration circuit integrates a predetermined current during the time A and discharges the predetermined current during the time B, and a predetermined current during the time C. And an integration circuit B for integrating and discharging a predetermined current during the time D.
(9) In (7) or (8), the position detecting pulse voltage generation circuit supplies the position detecting pulse voltage to the corners a plurality of times, and the integrating circuit supplies the position to each corner. A voltage obtained by adding a voltage corresponding to a time difference (A−B) or a time difference (C−D) when a pulse voltage for detection is supplied a plurality of times is output.
(10) In any one of (7) to (9), the coordinate position calculation circuit includes an A / D conversion circuit connected to a subsequent stage of the integration circuit.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
According to the display device with a touch panel of the present invention, it is possible to reduce the cost without reducing the light transmittance.

Hereinafter, embodiments in which the present invention is applied to a liquid crystal display device will be described in detail with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof is omitted.
[Position Detection Principle of Liquid Crystal Display Device with Touch Panel of the Present Invention]
FIG. 1 is a diagram for explaining the principle of position detection of a touch panel in a liquid crystal display device with a touch panel according to the present invention. The touch panel shown in FIG. 1 includes a substrate having a planar transparent conductive film formed on the surface on the observer side.
In FIG. 1A, reference numeral 1 denotes a transparent conductive film formed on a touch panel substrate. Now, when the observer's finger touches the point P in FIG. 1A of the transparent conductive film 1, the capacitive element C is inserted between the point P of the transparent conductive film 1 and the reference potential (GND). Will be.
In this state, a pulse voltage of Vin is supplied from the pulse voltage generation circuit 2 to the corner 3 among the four corners of the transparent conductive film 1, and from the corner (corner on the same diagonal line) 4 facing the corner 3 of the transparent conductive film 1. The rising time when the output pulse voltage rises from a predetermined voltage (Vref1) to a predetermined voltage (Vref2) is measured. FIG. 1B shows an equivalent circuit of the transparent conductive film 1 in this state, and FIG. 1C shows the rise time of the pulse voltage output from the corner 4 of the transparent conductive film 1 at that time. In FIG. 1C, Vout1 represents a pulse voltage output from the corner 4 of the transparent conductive film 1, and T1 represents a rise time.

Next, a pulse voltage of Vin is supplied from the pulse voltage generation circuit 2 to the corner 4 of the transparent conductive film 1, and the pulse voltage output from the corner 3 of the transparent conductive film 1 is changed from a predetermined voltage (Vref1) to a predetermined voltage. The rise time rising to the voltage (Vref2) is measured. FIG. 1D shows an equivalent circuit of the transparent conductive film 1 in this state, and FIG. 1E shows the rise time of the pulse voltage output from the corner 3 at that time. In FIGS. 1B and 1D, R1 is an equivalent resistance between the corner 3 and the point P of the transparent conductive film 1, and R2 is the difference between the corner 4 and the point P of the transparent conductive film 1. The equivalent resistance is shown. In FIG. 1E, Vout2 is a pulse voltage output from the corner 3 of the transparent conductive film 1, and T2 is a rise time.
Next, a time difference (T1−T2) between T1 and T2 is obtained. Here, T1> T2 when R1> R2, T1 = T2 when R1 = R2, and T1 <T2 when R1 <R2.
Therefore, if the time difference (T1-T2) is 0, it can be determined that the position touched by the observer's finger is the position of the center point of the transparent conductive film 1 (a point where two diagonal lines intersect).
If the time difference (T1-T2) is a positive value, the position touched by the observer's finger is a position between the center point and the corner 4 of the transparent conductive film 1, and the position is the time difference ( As the positive value of T1-T2) increases, it can be determined that the position touched by the observer's finger is closer to the corner 4.
Similarly, if the time difference (T1-T2) is a negative value, the position touched by the observer's finger is the position between the center point and the corner 3 of the transparent conductive film 1, and the position is the time difference. As the negative value of (T1-T2) decreases, it can be determined that the position touched by the observer's finger is closer to the corner 3.
By executing the above-described procedure for the corners 5 and 6 on the diagonal line of the transparent conductive film 1, the position on the touch panel touched by the observer's finger can be detected.

FIG. 2 is a diagram showing a schematic configuration of the touch panel in the liquid crystal display device with a touch panel according to the present invention, and FIG. 3 is a timing chart showing voltage waveforms of respective parts shown in FIG.
The corner 3, corner 4, corner 5, and corner 6 of the transparent conductive film 1 formed on the touch panel are connected to the pulse voltage generation circuit 2 through 7 to 10 switching and 11 to 14 respectively. It is connected to the buffer amplifier 15 through a switch.
For example, the switch 7 and the switch 13 are turned on in the cycle F1 shown in FIG. 3A, and the pulse voltage (see FIG. 3A) is supplied from the pulse voltage generation circuit 2 to the corner 3 of the transparent conductive film 1. Then, a pulse voltage (see FIG. 3B) that is output from the corner 4 of the transparent conductive film 1 and rises with a predetermined time constant is input to the comparator circuit 16 via the buffer amplifier 15. The buffer amplifier 15 is for increasing the impedance on the buffer amplifier side viewed from the corner 4 and preventing current from flowing into the corner 4. If a current flows into the corner 4, the rise time of the pulse voltage output from the corner 4 of the transparent conductive film 1 varies, and an error occurs in position detection in the transparent conductive film 1.

The comparator circuit 16 converts a pulse voltage output from the corner 4 of the transparent conductive film 1 and rising at a predetermined time constant into a signal having a first time width (T1 in FIG. 3C).
The comparator circuit 16 includes a comparator 19 to which the reference voltage 17 of Vref1 is input, a comparator 20 to which the reference voltage 18 of Vref2 is input, and an AND circuit 36 that performs a logical product of the comparator 19 and the comparator 20. Consists of.
The signal having the first time width turns on the switch 28 of the charge pump circuit 22 (see FIG. 3D) and outputs the current of the current source 27 to the integrating circuit 31.
A capacitor 33 connected between the inverting terminal and the output terminal of the operational amplifier 32 constituting the integrating circuit 31 according to the time width (T1 in FIG. 3C) of the signal having the first time width of the integrating circuit 31. Is charged. When the time width of the first time width signal is long, the charge amount is large, and when the time width is short, the charge amount is small.
The charge pump circuit 22 has 25 and 26 AND circuits. The AND circuit 25 turns on the switch 28 by the output of the comparator circuit 16 when the control signal 23 is High. The AND circuit 26 turns on the switch 29 by the output of the comparator circuit 16 when the control signal 24 is High.

Next, in the cycle F2 shown in FIG. 3A, the switches 9 and 11 are turned on, and the pulse voltage generation circuit 2 supplies the pulse voltage (see FIG. 3A) to the corner 4 of the transparent conductive film 1. Then, a pulse voltage (see FIG. 3B) output from the corner 4 of the transparent conductive film 1 and falling at a predetermined time constant is input to the comparator circuit 16 via the buffer amplifier 15.
In the circuit configuration shown in FIG. 1D, when a pulse voltage that changes from the reference voltage (GND) to the voltage Vin is supplied to the resistor R2, a predetermined voltage (Vref2) to a predetermined voltage (Vref2). In the circuit configuration shown in FIG. 1D, when the capacitor C is charged up to Vin and a pulse voltage that changes from Vin to the reference voltage (GND) is supplied to the resistor R2 in the circuit configuration shown in FIG. Since the fall time from the predetermined voltage (Vref2) to the predetermined voltage (Vref1) is the same, the corner 4 of the transparent conductive film 1 is changed from Vin to the reference voltage (GND) in FIG. A changing pulse voltage is supplied.
The comparator circuit 16 converts the pulse voltage output from the corner 4 of the transparent conductive film 1 and falling at a predetermined time constant into a signal having a second time width (T2 in FIG. 3C).
The signal having the second time width turns on the switch 29 of the charge pump circuit 22 (see FIG. 3E) and outputs the current of the current source 30 to the integrating circuit 31. As a result, the electric charge is discharged from the capacitor 33 of the integration circuit 31 in accordance with the time width of the second time width signal (T2 in FIG. 3C). When the time width of the second time width signal is long, the discharge amount is large, and when the time width is short, the discharge amount is small.

After following the above procedure, the output voltage (SV; see FIG. 3 (f)) of the integration circuit 31 is digitally converted by the A / D converter 35.
When the output of the integrating circuit 31 is a negative voltage, it means that the observer's finger touching the transparent conductive film 1 is closer to the corner 4. Conversely, when the voltage is positive, it means that the side closer to the corner 3 is touched, and when it is zero, it means that the distance between the corner 3 and the corner 4 is almost equal.
Accordingly, since the output voltage indicates to the integrating circuit 31 the relationship between the distance between the corner 3 and the corner 4 of the transparent conductive film 1, the digital conversion is performed between the corner 3 and the corner 4. You can get the coordinates of where you touched.
Next, after the switch 34 of the integrating circuit 31 is turned on and the capacitor 33 is reset, the pulse voltage is applied to the corners 5 and 6 of the transparent conductive film 1 as described above and appears diagonally. Then, a pulse voltage rising at a predetermined time constant or a pulse voltage falling at a predetermined time constant is converted into a signal having a time width, and an observer's The coordinates of the place touched by the finger can be obtained. This makes it possible to specify the position touched by the observer's finger on the touch panel.
When the output voltage of the integration circuit 31 is digitally converted by the A / D converter 35, the operations shown in FIGS. 3A to 3F are repeated a plurality of times to increase the voltage of the integration circuit 31. To A / D converter 35 for digital conversion.
Two sets of the buffer amplifier 15, the comparator circuit 16, the charge pump circuit 22, and the integrating circuit 31 can be prepared, one for the corner 3 and the corner 4 and one for the corner 5 and the corner 6.

[Example]
FIG. 4 is a diagram illustrating the transparent conductive film 1 on the touch panel substrate in the liquid crystal display device with a touch panel according to the embodiment of the present invention.
As shown in FIG. 4 (a), the liquid crystal display device with a touch panel of the present example is transparent in the transparent conductive film 1 formed on the touch panel substrate as shown in FIG. Different from the conductive film 1.
The equivalent circuit of the transparent conductive film 1 of the present embodiment is a circuit in which the resistance elements R are connected in a lattice form as shown in FIG.
FIG. 5 is a diagram showing a schematic configuration of the touch panel according to the embodiment of the present invention.
Also in this embodiment, a pulse voltage is sequentially applied from one of the four corners of the transparent conductive film 1, and the delay of the pulse voltage appearing on the diagonal is measured to obtain the coordinates of the part touched with the finger or stylus pen.
For example, the switch 7 and the switch 13 are turned on, the pulse voltage is applied from the pulse voltage generation circuit 2 to the corner 3 of the transparent conductive film 1, and the first delay signal (b in FIG. ) See).
Next, the rising delay time of the first delay signal is converted into a signal having a first time width (T1 in FIG. 3) corresponding to the first delay time using the comparator circuit 16.
The signal of the first time width turns on the switch 28 of the charge pump circuit 22 and outputs the current of the current source 27 to the integrating circuit 31, and the capacitor 33 according to the time width of the signal of the first time width. Charge is charged. When the time width is long, the charge amount is large, and when the time width is short, the charge amount is small.

Next, the switch 9 and the switch 11 are turned on to apply the pulse voltage from the pulse voltage generation circuit 2 to the corner 4 of the transparent conductive film 1, and from the corner 3 through the buffer amplifier 15 the second delayed signal ((( b) see). Similarly, a signal having a second time width (T2 in FIG. 3) corresponding to the second delay time is obtained from the second delay time using the comparator circuit 16.
The signal of the second time width turns on the switch 29 of the charge pump circuit 22 and outputs the current of the current source 30 to the integrating circuit 31. The electric charge is discharged from the capacitor 33 in accordance with the time width of the signal having the second time width. When the time width is long, the discharge amount is large, and when the time width is short, the discharge amount is small.
By following the above procedure, the output voltage of the integrator is digitally converted by the A / D converter 35.
Next, a pulse voltage is similarly applied to the corners 5 and 6, and the delay time of the signal appearing on the diagonal is converted into a pulse width. The coordinates of the place touched by the finger can be obtained.
As described above, the position where the finger touches the transparent conductive film 1 on the substrate of the touch panel is specified.
Further, the A / D converter 35 may perform digital conversion after the operation up to the integration circuit 31 described above is repeated a plurality of times to increase the output of the integration circuit.

As described above, in this embodiment, since the pulse voltage is alternately applied to the diagonal of the transparent conductive film 1, the noise generated on the transparent conductive film 1 can be canceled and the noise is reduced. A strong touch panel can be realized. In particular, when the present invention is applied to a display device with an input function integrated with a liquid crystal display panel, an EL panel, or the like, an input function resistant to noise generated from the liquid crystal display panel or the EL panel can be realized.
Furthermore, since this embodiment can be easily configured with a switch circuit, a comparator, a charge pump, and an integration circuit, the cost can be reduced.
Further, in this embodiment, since the transparent conductive film 1 has a lattice pattern, the resistance value of the transparent conductive film 1 can be equivalently increased, so that a large time constant can be secured. As a result, the delay time increases and the sensitivity can be improved.
For example, when the planar transparent conductive film 1 is used, according to an experiment, the resistance value of the planar transparent conductive film 1 is about 200Ω in a size of 3 inches diagonally. Assuming that the capacitance due to finger touch is 10 pF, the time constant is 2 ns. Even if the film thickness of the transparent conductive film 1 is reduced to increase the time constant, the time constant is about 4 ns and the time constant is about 20 ns even if the time constant is doubled 4 ns and the film thickness is 1/10.
Here, the time constant is the time constant of the integration circuit composed of the equivalent resistance (R1 or R2) and the capacitance (C) by finger touch shown in FIG. 1 (b) and FIG. 1 (d). To express.

On the other hand, in the transparent conductive film 1 having a grid pattern in this embodiment, the width and length of one side of the grid can be freely designed, and the resistance value can be controlled by the pattern shape. According to the experiment, when the resistance value of one side of the lattice is 10 kΩ and the matrix is 5 × 6 sides, the resistance value of the transparent conductive film 1 having the lattice pattern is about 26 kΩ diagonally. If the capacitance due to finger touch is 10 pF, the time constant is 258 ns, and the self-constant can be secured at a significantly larger value than when the planar transparent conductive film 1 is used.
Thus, in this embodiment, since the transparent conductive film 1 on the touch panel has a lattice pattern, a sufficiently large resistance value can be ensured, so that a large time constant can be obtained, and therefore the delay time can be measured. It becomes easy. In addition, it is desirable that the transparent conductive film 1 having a grid pattern has a film thickness of the transparent conductive film 1 and a width of the grid pattern so that the resistance value of one side of the grid is about 10 kΩ.
Further, in this embodiment, in order to increase the resistance value of the transparent conductive film 1, the transparent conductive film 1 is not thinned but has a lattice pattern. Thereby, in order to increase the resistance value of the transparent conductive film 1, it is not necessary to manufacture the transparent conductive film 1 having a thin film thickness with high accuracy, and it is possible to manufacture the transparent conductive film 1 with a film thickness convenient for the process and with a high yield.
Furthermore, since the setting of the resistance value of the transparent conductive film 1 can be made not dependent on the process but on the pattern design, the manufacturing becomes easy.
Moreover, in order to ensure the capacity | capacitance (C) by a finger touch, the one where the lattice pattern area of the transparent conductive film 1 is large is good, but a resistance value cannot be enlarged. Therefore, the width of one side of the grid for securing a large resistance value is sufficiently narrowed, and an island-like transparent conductive film (capacitance electrode) 11 is arranged inside the grid to secure the capacitance, and at any one point. The island-shaped transparent conductive film 11 and one side of the grid pattern may be electrically connected. The structure of the transparent conductive film 1 in this case is shown in FIGS.

6A to 6C, the resistance value of the transparent conductive film 1 can be ensured, and the capacitance (C) due to finger touch can also be ensured by the island-shaped transparent conductive film 11.
Note that the island-shaped transparent conductive film 11 and the grid pattern are electrically connected to only one place, and should not be connected to two or more places. This is because a current for coordinate detection also flows through the island-shaped transparent conductive film 11, which disturbs the resistance value of the entire transparent conductive film, and more specifically, lowers the resistance value. This is because it becomes impossible to ensure the above.
As shown in FIGS. 6A and 6B, the island-shaped transparent conductive film 11 has one island-shaped transparent conductive film (in FIGS. 6A and 6B) inside the lattice pattern. , One rectangular transparent conductive film) may be provided, but as shown in FIG. 6C, an island-shaped transparent conductive film divided into a plurality of parts may be used. In this case, each island-shaped transparent conductive film 11 is electrically connected to the grid pattern at an arbitrary point.
In FIG. 6C, four island-shaped transparent conductive films 11 are provided inside the lattice-shaped pattern, and four island-shaped transparent conductive films 11 are formed at arbitrary points from each island-shaped transparent conductive film 11. It is electrically connected to any one grid pattern in the pattern.
Regarding the transmittance, reflectance, and chromaticity of the reflected light, a difference occurs between the portion where the transparent conductive film is present and the portion where the transparent conductive film is not present. Therefore, the lattice pattern of the transparent conductive film 1 and the island-shaped transparent conductive film 11 are slightly different. However, the pattern shape may be visible. In order to make the pattern shape inconspicuous, one side of the lattice pattern is made as thin as possible, and the island-like transparent conductive film 11 formed inside is formed as large as possible, and the portion without the transparent conductive film is made as thin as possible. Is desirable.
In our study, when the portion without the transparent conductive film was 30 μm, the portion without the transparent conductive film appeared thin, and when it was 20 μm, it was almost invisible. Also, the result was invisible at 10 μm. Therefore, the portion without the transparent conductive film is preferably narrower than 30 μm and about 20 μm.

An IPS liquid crystal display device is known as a liquid crystal display device. In this IPS liquid crystal display device, a pixel electrode and a counter electrode are formed on the same substrate, and an electric field is applied between them to allow the liquid crystal to be flat on the substrate surface. The brightness is controlled by rotating it inside. For this reason, there is a feature that the density of the display image does not invert when the screen is viewed obliquely.
Unlike the TN liquid crystal display panel and the VA liquid crystal display panel, the IPS liquid crystal display panel has no counter electrode on a substrate on which a color filter is provided. Therefore, the back side transparent conductive film is formed on the substrate on which the color filter is provided for reasons such as reducing display noise.
By using the transparent electrode 1 of the touch panel of this embodiment as the back side transparent electrode, a liquid crystal display panel can be constructed without increasing the cost, and the transmittance of the liquid crystal display panel is also a conventional IPS liquid crystal. Can be the same as the display panel.
Hereinafter, an example of a liquid crystal display module using the back side transparent electrode as the transparent conductive film of the transparent conductive film 1 of the present embodiment will be described.

FIG. 7 is a block diagram showing a schematic configuration of an example of a liquid crystal display module that uses the back-side transparent electrode as the transparent conductive film of the transparent conductive film 1 of the present embodiment. The liquid crystal display module with a touch panel shown in FIG. 7 is a small liquid crystal display module used as a display unit of a mobile phone, a digital camera, or the like.
A liquid crystal display panel illustrated in FIG. 7 includes a first substrate (also referred to as a TFT substrate or an active matrix substrate) (SUB1) provided with a pixel electrode, a thin film transistor, and the like, and a second substrate (a counter electrode) on which a color filter or the like is formed. (Substrate) (SUB2) is overlapped with a predetermined gap, and both substrates are bonded together by a seal material provided in a frame shape in the vicinity of the peripheral edge between the two substrates, and part of the seal material. Liquid crystal is sealed and sealed inside the sealing material between the substrates from the provided liquid crystal sealing port, and a polarizing plate is attached to the outside of both substrates.
As described above, the liquid crystal display module illustrated in FIG. 7 has a structure in which liquid crystal is sandwiched between a pair of substrates.
The first substrate (SUB1) has a larger area than the second substrate (SUB2), and a thin film transistor is provided in a region of the first substrate (SUB1) that does not face the second substrate (SUB2). A semiconductor chip (Dr) that constitutes a driver for driving is mounted, and a flexible printed circuit board (FPC) is mounted on the periphery of one side of the region.

FIG. 8 is a plan view showing the configuration of one subpixel of the liquid crystal display panel shown in FIG.
FIG. 9 is a cross-sectional view showing a cross-sectional structure along the cutting line AA ′ shown in FIG. Hereinafter, the structure of the liquid crystal display panel shown in FIG. 7 will be described with reference to FIGS.
The liquid crystal display panel of this example is an IPS liquid crystal display panel using planar counter electrodes, and the main surface side of the second substrate (SUB2) is the observation side.
On the liquid crystal layer (LC) side of the second substrate (SUB2) made of a transparent substrate such as a glass substrate or a plastic substrate, a light shielding film (BM) is sequentially formed from the second substrate (SUB2) toward the liquid crystal layer (LC). ), A color filter layer (CF), an overcoat layer (OC), and an alignment film (AL2). Further, a back side transparent conductive film (CD) and a polarizing plate (POL2) are formed outside the second substrate (SUB2).
In addition, on the liquid crystal layer (LC) side of the first substrate (SUB1) made of a transparent substrate such as a glass substrate or a plastic substrate, scanning lines are sequentially arranged from the first substrate (SUB1) toward the liquid crystal layer (LC). (Also referred to as gate line) (GL; not shown), interlayer insulating film (PAS3), video line (also referred to as drain line or source line) (DL; not shown), interlayer insulating film (PAS2), planar A counter electrode (CT), an interlayer insulating film (PAS1), a pixel electrode (PX) composed of a comb electrode, and an alignment film (AL1) are formed. Further, a polarizing plate (POL1) is formed outside the first substrate (SUB1).
In FIG. 8, 52 is a gate electrode, 53 is a semiconductor layer, and 54 is a source electrode.

The liquid crystal display panel shown in FIG. 7 realizes a touch panel function by using the back side transparent conductive film (CD) as a transparent electrode of a capacitive coupling type touch panel. Therefore, the back side transparent conductive film (CD) shown in FIG. 7 also serves as the transparent conductive film 1 of the touch panel shown in FIG. In the configuration of FIG. 9, a polarizing plate (POL2) is disposed on the back side transparent conductive film. When the polarizing plate (POL2) is insulative, it may be assumed that the observer's finger does not function as a capacitor when the observer's finger touches the polarizing plate (POL2). In such a case, a conductive polarizing plate may be used as the polarizing plate (POL2).
Further, the pulse voltage generation circuit 2, the switches (7 to 14), the buffer amplifier 15, the comparator circuit 16, the charge pump circuit 22, the integration circuit 31, and the A / D converter 35 shown in FIG. You may mount in a chip | tip (Dr) or you may provide outside (here the main body side of a mobile telephone).

As described above, according to the liquid crystal display module shown in FIG. 7, the liquid crystal display including the capacitive coupling type touch panel that realizes low cost and high transmittance by utilizing the characteristics of the IPS liquid crystal display panel. Modules can be provided. That is, since the back side transparent conductive film (CD) is also used as a transparent electrode of a capacitively coupled touch panel, it is not necessary to provide a new glass substrate (that is, a touch panel substrate), and thus the transmittance is reduced. Can be prevented, and further, an increase in cost can be suppressed.
In addition, in the liquid crystal display module shown in FIG. 7, it is not necessary to provide a new glass substrate (that is, a touch panel substrate), so that the thickness of the liquid crystal display module can be reduced and the weight can be reduced. It is also possible.
Note that the present invention is not limited to an IPS liquid crystal display panel, but can be applied to a TN liquid crystal display panel and a VA liquid crystal display panel. However, it is necessary to form a transparent conductive film on the surface opposite to the side where the liquid crystal is disposed of the second substrate (SUB2) such as a TN liquid crystal display panel or a VA liquid crystal display panel. In the case of a liquid crystal display panel not provided, a transparent conductive film is newly formed.
The present invention is not limited to a liquid crystal display device, and can be applied to display devices such as an organic EL display device in general.
As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

It is a figure explaining the position detection principle of a touch panel in the liquid crystal display device with a touch panel of this invention. It is a figure which shows schematic structure of the touch panel shown in FIG. It is a timing chart which shows the voltage waveform of each part shown in FIG. It is a figure explaining the transparent conductive film on a touchscreen in the liquid crystal display device with a touchscreen of the Example of this invention. It is a figure which shows schematic structure of the touchscreen of the Example of this invention. It is a figure explaining the modification of the transparent conductive film on a touchscreen in the liquid crystal display device with a touchscreen of the Example of this invention. It is a block diagram which shows schematic structure of the liquid crystal display module with a touchscreen of the Example of this invention. It is a top view which shows the structure of 1 sub pixel of the liquid crystal display panel of the Example of this invention. It is sectional drawing which shows the cross-sectional structure along the AA 'cutting line shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent conductive film 2 Pulse voltage generation circuit 3, 4, 5, 6 Four corners 7-14, 28, 29, 34 of transparent conductive film 1 Switch 11 Island-shaped transparent conductive film 15 Buffer amplifier 16 Comparator circuits 17, 18 Reference | standard Voltage 19, 20 Comparator 22 Charge pump circuit 25, 26, 36 AND circuit 27, 30 Current source 31 Integration circuit 32 Operational amplifier 33 Capacitor 35 A / D converter 52 Gate electrode 53 Semiconductor layer 54 Source electrode SUB1, SUB2 Substrate LC Liquid crystal Layer POL1, POL2 Polarizing plate PAS1, PAS2, PAS3 Interlayer insulation film OC Overcoat layer AL1, AL2 Alignment film BM Shading film CF Color filter PX Pixel electrode CT Counter electrode CD Back side transparent conductive film DL Video line (drain line, source line) )
GL scanning line (gate line)
Dr Semiconductor chip FPC Flexible wiring board R1, R2 Equivalent resistance C Finger capacity

Claims (9)

It has a substrate having a transparent conductive film with a lattice pattern on the surface on the observer side,
The transparent conductive film is a touch panel used as a transparent electrode of a capacitively coupled touch panel,
A position detection pulse voltage generation circuit for inputting a position detection pulse voltage;
A coordinate position calculation circuit that calculates a touch position of the observer's finger to the conductive member;
The transparent conductive film has a shape having four corners,
The position detection pulse voltage generation circuit supplies a position detection pulse voltage to each of the four corners of the transparent conductive film at different timings,
When the position detection pulse voltage is supplied to one of the four corners of the transparent conductive film, the coordinate position calculation circuit outputs a voltage output from a corner on the same diagonal as the corner to which the pulse voltage is supplied. Based on the calculation of the touch position of the observer's finger to the conductive member,
When the two corners on one diagonal of the transparent conductive film are corner A and corner B, and the two corners on the other diagonal of the transparent conductive film are corner C and corner D, the coordinate position calculation circuit When a pulse voltage for position detection is supplied to the corner A of the conductive film, a time A when the voltage output from the corner B becomes a predetermined voltage, and a pulse voltage for position detection at the corner B of the transparent conductive film Is supplied, a time difference (A−B) from time B when the voltage output from the corner A becomes a predetermined voltage, and a pulse voltage for position detection is supplied to the corner C of the transparent conductive film. When the pulse C for position detection is supplied to the corner D of the transparent conductive film and the time C when the voltage output from the corner D becomes a predetermined voltage, the voltage output from the corner C is Based on the time difference (C−D) from the time D at which a predetermined voltage is reached, the conduction of the observer ’s finger. Features and to filter touch panel that calculates the touch position on the member. Having at least one island-shaped transparent conductive film inside the lattice pattern of the transparent conductive film;
The touch panel according to claim 1, wherein the at least one island-shaped transparent conductive film is electrically connected to the lattice pattern at an arbitrary point. The at least one island-shaped transparent conductive film is a square-shaped transparent conductive film,
The one rectangular transparent conductive film is electrically connected to any one of the four lattice patterns at any one point. 2. The touch panel according to 2. The at least one island-shaped transparent conductive film is four triangular transparent conductive films,
3. Each of the four triangular transparent conductive films is electrically connected to different lattice patterns among the four lattice patterns at an arbitrary point. The touch panel described. The pulse voltage for position detection supplied to the corner A or the corner C of the transparent conductive film is a pulse voltage that changes from the first voltage level to the second voltage level,
The touch panel according to claim 1 , wherein the position detection pulse voltage supplied to the corner B or the corner D of the transparent conductive film is a pulse voltage that changes from the second voltage level to the first voltage level. . The coordinate position calculation circuit has an integration circuit,
The integration circuit integrates a predetermined current during the time A or the time C, and discharges a predetermined current during the time B or the time D, whereby the time difference (A−B) or the time difference ( The touch panel according to claim 5, wherein a voltage corresponding to CD) is output. The integration circuit integrates a predetermined current during the time A, integrates a predetermined current during the time C, and an integration circuit A that discharges the predetermined current during the time B. The touch panel according to claim 6 , further comprising an integration circuit B that discharges a predetermined current. The position detection pulse voltage generation circuit supplies the position detection pulse voltage to each corner a plurality of times,
The integration circuit outputs a voltage obtained by adding a voltage corresponding to a time difference (AB) or a time difference (CD) when the position detection pulse voltage is supplied to each corner a plurality of times. The touch panel according to claim 7 . It said coordinate position calculation circuit includes a touch panel according to any one of claims 6 to 8, characterized in that it has an A / D converter circuit which is connected downstream of the integrator circuit.

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