WO2003042909A1

WO2003042909A1 - Electrode structure in touch screen

Info

Publication number: WO2003042909A1
Application number: PCT/KR2002/002089
Authority: WO
Inventors: Do-Il Kwak; Young-Soo Ahn
Original assignee: A. Touch Co., Ltd.
Priority date: 2001-11-14
Filing date: 2002-11-09
Publication date: 2003-05-22
Also published as: KR20030039654A

Abstract

An electrode structure for a touch screen is disclosed. In the touch screen, a transparent electrode is uniformly coated on a lower substrate. A plurality of X-axis and Y-axis potential compensation electrodes are formed of a layer having a lower sheet resistance than the transparent electrode and arranged at predetermined intervals in a predetermined pattern along the four edges of the lower substrate. At least one buffer electrode, having a sheet resistance between the sheet resistances of the transparent electrode and the potential compensation electrodes, is coated along the four edges of the lower substrate.

Description

ELECTRODE STRUCTURE IN TOUCH SCREEN

TECHNICAL FIELD

The present invention relates generally to a touch screen, and in particular, to a touch screen having a maximum active area with respect to its given size by forniing two or more layers having different sheet resistances along the four edges of the touch screen.

BACKGROUND ART

The operations and basic structures of resistive touch screens including four-wire and five-wire ones, touch screens using electrostatic capacitance, and other types of touch screens are well known and so configured as to be favorable to optimum design, satisfying characteristic requirements. In general, if an active area is wide, it facilitates design of an optimum touch screen.

Referring to FIG. 1, a conventional five-wire resistive touch screen 100 includes an upper substrate 105 and a lower substrate 101. On the lower substrate 101, a lower transparent conductive film 108 and four wirings for a position signal 102 are connected to an external system connector. X-axis and Y-axis potential compensation electrodes 103 and 104 are formed on the lower transparent conductive film 108. The upper substrate 105 has an upper transparent conductive film 108 and a single signal sensing wire 106 for sensing position signals distributed over the lower substrate 101, which are connected to the external system connector. As compared to a four-wire resistive touch screen having two X-axis and Y-axis potential compensation electrodes on each of its upper and lower plates, for an additional function of position signal application, the X-axis and Y-axis potential compensation electrodes 103 and 104 are arranged along the four edges of the lower plate 101 and the single signal sensing wire 106 is formed on the upper substrate 105.

More specifically, the lower transparent conductive film 108 is formed on the lower substrate 101 and then the potential compensation electrodes 103 and 104 are arranged on the lower transparent conductive film 108 along the four edges of the lower substrate 101. The position signal applying wires 102 having position terminals a to d are formed by removing an area of ΔL_A and ΔL_B from the lower transparent conductive film 108 or forming an insulation film on the lower transparent conductive film 108. Since X-axis and Y-axis position signals must be applied concurrently on the lower substrate 101, relative to the four- wire resistive touch screen, the respective X-axis and Y-axis potential compensation electrodes 103 and 104 are spaced on the lower transparent conductive film 108. Therefore, the resistance between potential compensation electrodes 103 or 104 is determined mostly by the ratio of their gap to the length of adjacent electrode surfaces in order to control the resistance. If the resistance is too low, the entire resistance of the touch screen is low, thereby adversely influencing the structure of a driving circuit and power consumption. Particularly, the X-axis potential compensation electrodes 103 for sensing

X-axis coordinates are designed by setting the resistance between Y-axis potential compensation electrodes 104 such that equi-potential fields are distributed perpendicularly to the X axis. Similarly, the Y-axis potential compensation electrodes 104 for sensing Y-axis coordinates are designed by setting the resistance between X-axis potential compensation electrodes 103 such that equi- potential fields are distributed perpendicularly to the Y axis.

On the other hand, the upper substrate 105 has the single position signal sensing wire 106 on it. Since the position signal sensing wire 106 simply senses position signals distributed over the lower substrate 101, there is no need for forming it of a metal having low resistance to sense a potential signal.

The upper substrate 105 is formed of a flexible material. While the transparent conductive films 108 can be used irrespective of sheet resistance, it is preferable that they have a sheet resistance of about 1000Ω/ or lower.

In the same manner as done for the four-wire resistive touch screen, the five-wire resistive touch screen is formed by combining the upper substrate 105 with the lower substrate 101.

Dot spacers 110 are arranged at predetermined intervals in an active area, and insulation material applied on the two substrates 101 and 105 is glued or an adhesive is used onto the substrates in a non-active area, to thereby insulate the transparent conductive films 108 from each other.

Thus, the above five-wire resistive touch screen senses contact and obtains the X- and Y- coordinates of a touched position in the following three steps.

- Step 1: contact is sensed. Upon finger-touch or pen-touch, the touch panel 100 senses the touch by applying a voltage between the upper and lower plates 105 and 101 and sensing the presence or absence of current.

- Step 2: an X-axis coordinate is sensed. Equi-potential fields are distributed in parallel to the Y-axis on the lower transparent conductive film 108 according to the sensed touch, and the potential of a finger-touched or pen- touched point P is transferred to the position signal sensing wire 106 via the upper transparent conductive film 108 between a position P' and the position signal sensing wire 106. - Step 3: a Y-axis coordinate is sensed. Equi-potential fields are distributed in parallel to the X-axis on the lower transparent conductive film 108, and the potential of the finger-touched or pen-touched point P is transferred to the upper plate 105 via contact resistance.

Here, if the finger touch or pen touch on the touch screen is not sensed, step 1 is repeatedly performed at predetermined intervals.

The typical five-wire resistive touch screen senses pressure applied to the upper plate 105, extracts the X and Y coordinates of the touched position, and displays them in the above-described steps. Therefore, even if the upper plate 105 is partially damaged, which is encountered with the four-wire resistive touch screen, the five-wire resistive touch screen operates normally after damage compensation. This is a characteristic requirement that a five-wire resistive touch screen satisfies unlike a four- or eight-wire resistive touch screen.

However, the five- wire resistive touch screen is not suitable in structure enough to satisfy the requirements of small size, light weight, and slimness. Moreover, it has the problem of an increase in a non-active area, i.e., a decrease in an active area caused by inappropriate arrangement of signal sensing and applying wires.

FIG. 2 illustrates the design of the conventional lower plate 101. It includes the lower transparent conductive film 108 on it. The potential compensation electrodes 103 and 104 are arranged close to the lower transparent conductive film 108 along the Y and X axes, respectively. The four position signal applying wires 102 are formed along the electrodes 103 and 104. Minimum areas ΔL_A and ΔL_B are spared to form the position signal applying wires 102 and the electrodes 103 and 104 on the lower substrate 101. Now, the reason why the active area is scaled down will be described below with reference to FIG. 2.

Referring to FIG. 2, although an area al is a maximum available active area on the lower substrate 101, a real active area is a2 because the width of the electrodes 103 and 104 and the areas ΔL_A and ΔL_B for forming the signal applying wires 102 therein push arrangement of the electrodes 103 and 104 inward.

Aside from the ΔL_A and ΔL_B wiring areas, a non-active area a3 is defined inside the potential compensation electrodes 103 and 104. The increase of the non-active area a3 along the X and Y axes is equivalent to the decrease of the available active area al. That is, the increased non-active area is an obstacle to maximum utilization of the available active area. This implies that a small, lightweight touch screen cannot be designed. As described before, the four position signal applying wires 102 are formed on the conventional five-wire resistive touch screen or an electrostatic type touch screen. In the former, the single wire 106 is additionally formed on the upper substrate 105 to sense position signals distributed on a lower substrate. As compared to the four-wire resistive touch screen, the potential compensation electrodes 103 and 104 are arranged along the four edges of the lower substrate

101 to additionally apply X-axis and Y-axis position signals in the five-wire resistive touch screen.

That is, the lower transparent conductive film 108 having a high resistance is formed on the lower substrate 101, and the potential compensation electrodes 103 and 104 are formed of a low-resistance metal on the lower transparent conductive film 108 along the four edges of the lower substrate 101. To form the potential compensation electrodes 103 and 104, the areas ΔL_A and ΔL_B are removed from the lower conductive film 108, or an insulation film is formed over the areas ΔL_A and ΔL_B of the lower conductive film 108. To apply X-axis and Y-axis position signals must be applied concurrently, the respective X-axis and Y-axis potential compensation electrodes 103 and 104 are formed on the lower transparent conductive film 108. Therefore, the resistance between potential compensation electrodes 103 or 104 is determined mostly by the ratio of their gap to the length of adjacent electrode surfaces in order to control the resistance. This means that resistance between potential compensation electrodes must be considered when designing them. If the difference in resistance between the lower conductive film 108 and the potential compensation electrode layers is wide, a good potential distribution can be achieved. However, when the resistance of the potential compensation electrodes 103 and 104 is too low, the overall resistance of the touch screen is decreased, thereby deadly influencing the structure of a driving circuit and power consumption.

The potential compensation electrodes 103 and 104 must be designed such that equi-potential fields are formed perpendicularly to a signal applying direction when X-axis and Y-axis signals are changed periodically because the X- axis and Y-axis signals are applied on the lower substrate 101, as compared to the four-wire resistive touch screen.

An active area is defined to be an area in which equi-potential fields are formed, and a non-active area is disposed between the active area and the edges of a substrate. When potentials are compensated using a plurality of electrodes, there is a space intervened between the potential compensation electrodes 103 and 104 and the active area as illustrated in FIG. 2. As the number of potential compensation electrodes increase in number over a given area, the space is decreased.

The lower substrate 101 in the five- wire resistive touch screen can adopt the following electrode structures: (1) a simple closed-curve compensation electrode structure in which the resistance ratio of the sheet to the potential compensation electrodes is set to be very high, thereby maximizing effects (see

FIG. 3); (2) a simple potential compensation closed-curve compensation electrode structure improved from the closed-curve compensation electrode structure, in which the potential compensation electrodes are modified according to a potential distortion pattern (see FIG. 5); (3) a geometrical potential compensation electrode structure in which the resistance of the potential compensation electrodes is determined by the geometrical form of the transparent conductive film having a high resistance by controlling a resistance ratio of a low-resistance metal to a high-resistance metal to the highest limit (see FIG. 6); (4) a potential compensation geometrical potential compensation electrode structure similar to the simple potential compensation closed-curve compensation electrode structure, in which the geometrical potential compensation electrodes are modified according to a potential distortion pattern, for fine adjustment of the geometrical potential compensation electrodes (see FIG. 7); and (5) a buffer layer-based compensation structure using an electrical buffer layer to minimize the gap between the potential compensation electrodes and the active area (see FIG. 8).

FIG. 3 illustrates electrodes in a simple closed-curve compensation electrode structure on the lower substrate 101 as disclosed in the United States Patent No. 3,591,718. This electrode structure is easy to design. Potential compensation electrodes 103 and 104 shaped into closed curves are arranged on the four corners. The resistance ratio of the potential compensation electrodes 103 and 104 to the lower conductive film 108 determines potential distribution characteristics. As the resistance ratio increases, equi-potential fields are formed perpendicularly to a signal applying direction. If there is no resistance difference between them, signal distortion becomes severe. Therefore, the resistance ratio needs to be great in this electrode structure. While there is little gap between the potential compensation electrodes 103 and 104 and the active area, and thus the non-active area can be reduced, it is very difficult to accurately set a resistance ratio that avoids potential distortion. In real implementation, potential distortion is worse farther from a signal applying portion as illustrated in FIG. 4. This phenomenon causes discrepancy between a touched point and a cursor on a display.

Referring to FIG. 5, a simple potential compensation closed-curve compensation electrode structure, as disclosed in the U.S. Patent No. 3,670,103, was proposed to compensate the potential distortion which becomes more serious farther from the signal applying portion in the simple closed-curve compensation electrode structure. In this electrode structure, the signal applying portion is positioned far from the active area. The potential compensation electrodes 103 and 104 are modified with their width maintained constant as illustrated. The resulting increase of the non-active area is not favorable to realization of a lightweight, small size touch screen.

A geometrical potential compensation electrode structure as disclosed in the U.S. Patent No. 4,731,508 is illustrated in FIG. 6, wherein equi-potential fields are formed by the transparent conductive film 108, the ratio of the gap (L) between potential compensation electrodes 103 and 104 to the length (W) of an adjacent electrode surface, and sheet resistance. To achieve a good potential distribution, resistance on the potential compensation electrodes must be lower than the resistance of the high-resistance transparent conductive film 108. The resistance of the electrodes 103 and 104 can be decreased by reducing the gap L and increasing the length W.

This electrode structure also exhibits voltage drop more serious farther from the signal applying portion, thus requiring compensation for the voltage decrease at the center of the electrodes. Consequently, the active area in which equi-potential fields are parallel is decreased in order to perform the voltage compensation and induce more occurrences of voltage drop at the signal applying portion.

FIG. 7 illustrates a geometrical potential compensation electrode structure disclosed in the U.S. Patent No. 5,736,688. In the same manner as illustrated in FIG. 5, the electrodes are formed according to a potential distortion pattern to overcome the shortcoming of the geometrical potential compensation electrodes illustrated in FIG. 6. The potential compensation electrodes are farther from the signal applying portion as they are more close to the active area. However, this electrode structure also increases the non-active area. FIG. 8 illustrates a buffer layer-based compensation structure disclosed in the U.S. Patent No. 4,649,232. To narrow the gap between the active area and the electrodes, a layer having a low resistance than the transparent conductive film 108 is formed around the electrodes at the four sides. Since an external signal is applied to each potential compensation electrode, the number of electrodes within a predetermined non-active area is limited. As the number of electrodes increases, the number of leads 112 increases and thus the non-active area is increased. As a result, the number of the electrodes within a given area is limited. The resulting increase of the gap between electrodes brings about the increase in the gap between the active are and the electrodes. To prevent this problem, buffer layers 111 formed of a metal having a lower resistance than the transparent conductive film are arranged between electrodes along the four sides.

However, as illustrated in FIGs. 9 A and 9B, there is no notable difference in equi-potential distribution between electrodes with buffer layers 111 interposed and the electrodes without buffer layers. That is, the buffer layer application is not effective. Consequently, the buffer layer-based compensation electrode structure has limitations in its effectiveness of narrowing the gap between the active area and the electrodes. While the above conventional electrode structures were intended to expand an active area on a touch screen using potential compensation electrodes or buffer layers, they are not effective. That is, they are not suitable for a lightweight, small size touch screen.

DISCLOSURE OF THE INVENTION

It is, therefore, an object of the present invention to provide an improved touch screen with the increase of a non-active area suppressed by potential compensation electrodes. It is another object of the present invention to provide a touch screen with a wide available active area obtained by changing an electrode layout.

It is a further object of the present invention to provide a compact touch screen of which the display area is increased with no increase in its overall size.

To achieve the above and other objects, there is provided an electrode structure for a touch screen. According to one aspect of the present invention, in a touch screen, a transparent electrode is uniformly coated on a lower substrate. A plurality of X-axis and Y-axis potential compensation electrodes are formed of a layer having a lower sheet resistance than the transparent electrode and arranged at predetermined intervals in a predetermined pattern along the four edges of the lower substrate. At least one buffer electrode, having a sheet resistance between the sheet resistances of the transparent electrode and the potential compensation electrodes, is coated along the four edges of the lower substrate.

According to another aspect of the present invention, in a touch screen, a transparent electrode is uniformly coated on a lower substrate. A plurality of X- axis and Y-axis potential compensation electrodes are formed of a layer having a lower sheet resistance than the transparent electrode and arranged at predetermined intervals in a predetermined pattern along the four edges of the lower substrate. At least one buffer electrode, having a sheet resistance between the sheet resistances of the transparent electrode and the potential compensation electrodes, is coated along the four edges of the lower substrate. A potential distribution compensation electrode is further provided to uniformly distribute potentials generated from potential compensation electrodes nearest to an active area defined by the plurality of potential compensation electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description

_* when taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates the vertical structure of a typical five-wire resistive touch screen;

FIG. 2 illustrates a conventional electrode structure for a lower substrate in a touch screen;

FIG. 3 illustrates another conventional simple closed-curve compensation electrode structure for the lower substrate in the touch screen;

FIG. 4 illustrates potential distribution the lower substrate in the conventional touch screen; FIG. 5 illustrates a third conventional simple potential compensation closed-curve compensation electrode structure for the lower substrate in the touch screen;

FIG. 6 illustrates a fourth conventional geometrical potential compensation electrode structure for the lower substrate in the touch screen; FIG. 7 is another diagram illustrating the fourth conventional geometrical potential compensation electrode structure for the lower substrate in the touch screen;

FIG. 8 illustrates a fifth conventional buffer layer-based potential compensation electrode structure for the lower substrate in the touch screen; FIG. 9 A illustrates an equi-potential distribution on the lower substrate of the conventional touch screen without buffer layers;

FIG. 9B illustrates an equi-potential distribution on the lower substrate of the conventional touch screen with buffer layers; FIG. 10 illustrates an embodiment of an electrode structure for a lower substrate in a touch screen according to the present invention;

FIG. 11 illustrates the vertical structure of electrodes in the lower substrate of the touch screen according to the embodiment of the present invention;

FIG. 12 illustrates the electrode structure illustrated in FIG. 10 in detail;

FIG. 13 illustrates another embodiment of the electrode structure for the lower substrate in the touch screen according to the present invention;

FIG. 14 illustrates a third embodiment of the electrode structure for the lower substrate in the touch screen according to the present invention; and

FIGs. 15A and 15B illustrate the potential distribution characteristics of a conventional electrode structure and an electrode structure according to the present invention, respectively.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention provides an electrode structure that overcome the problem of the simple closed-curve compensation electrode structure in which the width or thickness of compensation electrodes must be increased to set a good resistance ratio of the compensation electrodes to a transparent electrode, and the problem of the geometrical potential compensation electrode structure in which the number of compensation electrodes must be limited to narrow the gap between compensation electrodes and increase the length of an adjacent electrode surface.

FIG. 10 is a planar view of an electrode structure for a lower substrate according to the present invention and FIG. 11 illustrates the vertical structure of electrodes on the lower substrate according to the present invention.

Referring now to FIG. 10, a lower transparent electrode 130 is coated uniformly on a lower substrate 120. X-axis and Y-axis potential compensation electrodes 140 and 150, of which resistance may be adjusted to a predetermined value appropriately, are arranged along the four edges of the lower transparent electrode 130. The potential compensation electrodes 140 and 150 are formed at predetermined intervals and in a predetermined pattern, using a layer having a lower resistance than the sheet resistance of the lower transparent electrode 130. At least one buffer electrode 160 having a sheet resistance defined in between the sheet resistance of the electrodes 140 (or 150) and the sheet resistance of the transparent electrode 130 is formed by coating onto the four sides of the lower substrate 120 thereon coated with the potential compensation electrodes 140 and 150. Potential distribution compensation electrodes are further provided to uniformly distribute potential generated from the potential compensation electrodes 140 and 150 nearest to an active area. An upper substrate includes an upper transparent electrode corresponding to the lower transparent electrode 130. Referring to FIG. 11, the potential compensation electrodes 140 and 150 are formed using a layer having a lower sheet resistance than the lower transparent electrode 130 in a predetermined pattern at predetermined intervals along the four edges of the lower substrate 120, as described above. The buffer electrode 160 having a resistance between the lOOΩ/sq. or higher sheet resistance of the transparent electrode 130 and the lΩ/sq. or lower sheet resistance of the potential compensation electrodes 140 and 150 is coated along the four edges of the lower substrate 102 over the area in which the potential compensation electrodes 140 and 150 are formed.

Although the sequence of coating the layers is changed, their electrical characteristics are not changed. One or more buffer electrodes 160 can be adopted and the number of each of other buffer layers is not limited either.

The potential distribution compensation electrodes 170 having a width W are further provided inside the buffer electrode layer 160 nearest to the active area in order to uniformly distribute potentials generated from the potential compensation electrodes. FIG. 12 illustrates the potential compensation electrodes in detail according to the present invention. Referring to FIG. 12, the resistance between potential compensation electrodes is determined the width, length, and sheet resistance of the buffer electrode layer 160 between adjacent potential compensation electrodes 140 and 150. Since the resistance between the potential compensation electrodes 140 and 150 is determined not by the sheet resistance of the transparent electrode layer 130 but by the sheet resistance of the buffer electrode layer 160, the pitch between compensation electrodes, in which some potential compensation electrodes 104 and 105 are repeated, becomes shorter even though the same resistance is set in a given area. Therefore, more electrodes can be formed and thus the non-active area is decreased, that is, the active area is increased.

The potential distribution compensation electrodes 170 inside the buffer electrode layer 160 between the potential compensation electrodes 140 and 150 nearest to the active area boundary distributes potentials uniformly to thereby widen the active area within a given screen size. The potential distribution effect is maximized by appropriately adjusting the width W of the potential distribution compensation electrodes 170. In other words, an optimum design of reducing the non-active area is enabled simply by adjusting the width of the potential distribution compensation electrodes 170.

FIG. 13 illustrates another embodiment of the electrode structure according to the present invention. To cope with potential distortion, the widths wl to n between the potential distribution compensation electrodes 170 and the distances dl to n between the potential distribution compensation electrodes 170 and main potential compensation electrodes 140 and 150 are adjusted. This electrode structure is based on the idea that the width W is increased and the distance d is decreased farther from a signal applying portion to the center to compensate for potential distortion. FIG. 14 illustrates a third embodiment of the electrode structure according to the present invention. The area for forming the buffer electrode layer 160 therein does not include the area of the potential distribution compensation electrodes 170. The buffer electrode layer area overlaps with the area for the main potential compensation electrodes 140 and 150. In this electrode structure, the main potential compensation electrodes 140 and 150 are the only factor to shorten the pitch between compensation electrodes, but the potential distribution compensation electrodes 170 simply function to distribute potentials. This electrode structure facilitates calculation of the resistance between potential compensation electrodes, thereby increasing a designing speed. FIGs. 15A and 15B illustrate a comparison in potential distribution characteristics between a conventional electrode structure and an electrode structure according to the present invention.

In the conventional electrode structure, as noted from FIG. 15 A, an active area is much spaced from potential compensation electrodes because the number of potential compensation electrodes available in a given area is less than in the present invention.

Referring to FIG. 15B, the number of potential compensation electrodes can be adjusted freely according to the sheet resistance of a buffer electrode in the electrode structure of the present invention. Thus, an active area boundary can be set to be nearer to the potential compensation electrodes. This implies that a non- active area is decreased and an active area is increased as much. Therefore, this electrode structure is favorable to realization of a lightweight, small size touch screen. In accordance with the present invention, a wide active area is secured by modifying an electrode layout on a substrate, which enables a compact touch screen to be realized. Furthermore, an effective screen size is increased without the overall touch screen size. Thus the touch screen becomes small, lightweight and slim.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A touch screen having a substrate with a transparent electrode formed thereon, at least one potential compensation electrode of a predetermined resistance arranged on the transparent electrode along the sides of the transparent electrode, and a plurality of electrical wirings for applying a signal thereto, said touch screen comprising: a plurality of X-axis and Y-axis potential compensation electrodes formed of a layer having a first sheet resistance lower than that of the transparent electrode, said potential compensation electrodes being arranged at predetermined intervals and in a predetermined pattern along four sides of the substrate on which the transparent electrode is coated evenly; and at least one buffer electrode formed on the substrate along the four sides of the substrate, said buffer electrode having a second sheet resistance defined in between the sheet resistance of the transparent electrode layer and the sheet resistance of the potential compensation electrodes.

2. The touch screen according to claim 1, wherein said second sheet resistance of the buffer electrode is defined in between the sheet resistance of the transparent electrode and the sheet resistance of the potential compensation electrodes, in which the sheet resistance of the transparent electrode is of lOOΩ/sq. or higher, while the sheet resistance of the potential compensation electrodes is of lΩ/sq. or lower.

3. The touch screen according to claim 1, wherein said at least one buffer electrode is respectively formed on selected ones of the four sides of the substrate on which the plurality of potential compensation electrodes are formed, and the buffer electrode substantially has a coating area corresponding to that of the potential compensation electrodes.

4. The touch screen according to claim 1, further comprising at least one second buffer electrode having different electrical characteristics from said at least one buffer electrode, wherein the buffer electrode layer is disposed between the transparent electrode layer and the potential compensation electrode layer.

5. A touch screen having a substrate with a transparent electrode formed thereon, and at least one X-axis and Y-axis potential compensation electrode of a predetermined resistance arranged on the transparent electrode along the sides of the transparent electrode, said touch screen comprising: a plurality of potential compensation electrodes formed of a layer having a sheet resistance lower than that of the transparent electrode, said potential compensation electrodes being arranged at predetermined intervals and in a predetermined pattern along four sides of the substrate on which the transparent electrode is coated evenly; at least one buffer electrode formed on the substrate along the four sides of the substrate, said buffer electrode having a sheet resistance defined in between the sheet resistance of the transparent electrode layer and the sheet resistance of the potential compensation electrodes; and a potential distribution compensation electrode for uniformly distributing electric potentials generated from an inner part of a potential compensation electrode nearest to an active area formed with said plurality of potential compensation electrodes.

6. The touch screen according to claim 5, wherein the distribution of electric potentials is controlled by adjusting a width of the potential distribution compensation electrode.

7. The touch screen according to claim 5, wherein as it goes further toward a center of the substrate from its signal input portion, the width (w) of the potential distribution compensation electrode increases and the distance (d) between the potential distribution compensation electrode and the potential compensation electrodes decreases, so as to compensate any potential distortion by adjusting the width (wl, w2, . . . n) of the potential distribution compensation electrode and the distance (dl, d2, . . . n) between the potential distribution compensation electrode and the potential compensation electrodes.

8. The touch screen according to claim 5, wherein an area in which the buffer electrode layer is formed includes an area in which the potential distribution compensation electrode is formed.

9. The touch screen according to claim 5, wherein the area of the buffer electrode layer is formed so as to cover only the area in which the potential compensation electrodes are formed, excepting the area in which the potential distribution compensation electrode is formed.