WO2008093914A1

WO2008093914A1 - Touch location detecting apparatus for a display screen

Info

Publication number: WO2008093914A1
Application number: PCT/KR2007/002557
Authority: WO
Inventors: Ki Eung Kim
Original assignee: Melfas, Inc.
Priority date: 2007-02-01
Filing date: 2007-05-25
Publication date: 2008-08-07

Abstract

The present invention relates to an apparatus for detecting a touch location of a user on a display screen. The touch location detecting apparatus of the invention includes: a transparent insulating panel, provided on a front surface portion of the display screen, for receiving the user's touch; a transparent conductive panel provided between the transparent insulating panel and the display screen and having a uniform resistance component; an electrode unit having a plurality of electrodes formed respectively at a plurality of locations on the transparent conductive panel; charge-discharge characteristic measuring unit for measuring a charge-discharge characteristic signal indicating charge/discharge characteristics of an electric charge to be supplied through the electrode unit; and a touch location calculating unit for calculating the touch location on the transparent insulating panel based on the measured charge-discharge characteristic signal. Accordingly, a touch location detecting apparatus with high durability and minimized loss of definition is provided.

Description

TOUCH LOCATION DETECTING APPARATUS FOR A

DISPLAY SCREEN

Technical Field

[1] The present invention relates to an apparatus for detecting the location of a user's touch on a display screen and a user input device for controlling the display screen by using touch location information detected by the apparatus. Background Art

[2] Conventionally, a user input interface of a digital computer system having a display screen is comprised of individual input devices separated from the display screen, for example, a keyboard, a mouse, buttons, etc. However, as the complexity of user applications operating on the computer system gradually increases and a variety of hardware devices dedicated to specific applications such as mobile phones and digital cameras are developed, the need for more intuitive user interfaces emerges. In response to this need, a touchscreen is widely employed in various digital equipments in recent years.

[3] The touchscreen refers to an input device used for detecting the location of a user's touch on a display screen and controlling a computer system and the display screen by using information on the detected touch location as input information. At present, most touchscreen employs a so-called "resistive type" principle as its detection principle for the user's touch. Fig. 1 schematically illustrates the structure of a conventional touchscreen employing this principle.

[4] The touchscreen shown in Fig. 1 includes two sheets of transparent conductive panels 110 and 120 provided on the front surface of the display screen. Each of the transparent conductive panels 110 and 120 is generally made of a transparent substrate having a conductive material, such as ITO (Indium Tin Oxide), coated on one surface. Provided on the lower panel 110 are two electrodes 111 and 112 that are linearly arranged respectively along its facing edges, and these electrodes 111 and 112 are connected to a positive (+) and a negative (-) terminal of a DC power source 113, respectively. Meanwhile, the upper panel 120 is disposed to cover the front surface of the lower panel 110 at a predetermined spacing, and has an electrode 121 prepared on one edge thereof.

[5] Fig. 2 illustrates a cross-sectional structure of the touchscreen depicted in Fig. 1 and its touch location detection principle. According to the cross- sectional structure as shown in Fig. 2, the upper panel 120 is supported by spacers 130 to cover the front surface of the lower panel 110 at a predetermined spacing without forming contacts with the lower panel 110. On the other hand, the lower panel 110 is supported by a transparent substrate 140, which serves to prevent deformation of the upper and the lower panel 110 and 120 in case an excessive force is applied.

[6] When a voltage V is applied between the electrodes 111 and 112 on the lower panel 110 by the DC power source 113, there are formed equipotential surfaces having an electric potential decreasing linearly in a direction from the electrode 111 connected to the (+) terminal to the electrode 112 connected to the (-) terminal of the DC power source 113. Meanwhile, since the upper panel 120 is formed of a flexible material, when a pressure is applied to a touch location 150 of a user, the bottom surface of the upper panel 120 and the top surface of the lower panel 110 which is supported by the transparent substrate 140 are contacted with each other at the touch location 150. As the bottom surface of the upper panel 120 and the top surface of the lower panel 110 are respectively coated with a transparent conductive material, an electric potential V of the touch location 150 can be measured through the electrode 121 on the upper panel 120.

[7] As shown in Fig. 2, since the electric potential of the equipotential surfaces formed side by side in the X-direction from the electrode 111 to the electrode 112 linearly decreases with respect to a distance in the X-direction from the electrode 111 to the touch location 150, information on the distance x in the X-direction from the electrode

111 to the touch location 150 can be extracted from the electric potential V measured through the electrode 121 on the upper panel 120.

[8] The same principle as above can also be used for extracting a distance in the Y- direction. That is, linear electrodes are arranged on the edges of the upper and the lower side of the lower panel 110, respectively, and a predetermined level of voltage is applied by a DC power source and then a distance y in the Y-direction can be extracted by using the electric potential value measured through the electrode 121 on the upper panel 120.

[9] In the above-described conventional touchscreen, by using the principle of a voltage divider, (x, y) coordinate can be acquired at a location where a pressure is applied through the use of a finger or stylus pen. However, the conventional touchscreen has a structure in which a mechanical pressure continuously applied to the upper panel 120 results in a deformation of the upper panel 120 and a change in the conductive characteristics of the coating surface formed by, e.g., ITO material having a brittle property, thereby easily deteriorating performance. This deterioration in performance can be a very serious problem when considering that a smaller size of the display screen for miniaturized digital equipments would result in a greater amount of bending moment to the upper panel 120 under the mechanical pressure applied thereto.

[10] In addition, because each of the upper and the lower panel 110 and 120 coated with a transparent conductive material such as ITO has a transparency of only 80% to 90%, the conventional touchscreen having a structure in which the upper and the lower panel 100 and 120 are overlapped on the front surface of the display screen has the problem of degrading the definition of the display screen.

[11] The present invention has been made in an effort to solve the above-mentioned problems of the conventional touchscreen and to propose a touch location detecting apparatus having a structure applicable to various types of digital equipments. Disclosure of Invention Technical Problem

[12] It is, therefore, a primary object of the present invention to provide a touch location detecting apparatus having a structure applicable to display devices having various shapes and sizes.

[13] Another object of the present invention is to provide a touch location detecting apparatus which does not accompany performance degradation that may be caused by a mechanical pressure, and thus has a longer lifetime than a conventional touchscreen.

[14] Still another object of the present invention is to provide a touch location detecting apparatus capable of improving the definition of a display screen as compared to a conventional touchscreen. Technical Solution

[15] In accordance with one aspect of the present invention, there is provided a touch location detecting apparatus including: a transparent insulating panel, provided on a front surface portion of a display screen, for receiving the user's touch; a transparent conductive panel provided between the transparent insulating panel and the display screen and having a uniform resistance component; an electrode unit having a plurality of electrodes formed respectively at a plurality of locations on the transparent conductive panel; a charge-discharge characteristic measuring unit for measuring a charge-discharge characteristic signal indicating charge/discharge characteristics of an electric charge to be supplied through the electrode unit; and a touch location calculating unit for calculating the touch location on the transparent insulating panel based on the measured charge-discharge characteristic signal.

[16] In accordance with another aspect of the present invention, there is provided a touch location detecting apparatus including: a transparent insulating panel, provided on a front surface portion of a display screen, for receiving the user's touch; a transparent conductive panel provided between the transparent insulating panel and the display screen and having a uniform resistance component; an electrode unit including a plurality of electrodes formed respectively at a plurality of locations on the transparent conductive panel; a transient response measuring unit for applying a voltage pulse through the electrode unit and measuring a transient response signal for the applied voltage pulse; and a touch location calculating unit for calculating the touch location on the transparent insulating panel based on the measured transient response signal. [17] In accordance with still another aspect of the present invention, there is provided a user input device including an input control unit for extracting control information for a display screen from the touch location information detected by the above-mentioned touch location detecting apparatus that is provided on a front surface portion of the display screen.

Brief Description of the Drawings [18] Fig. 1 is a view schematically illustrating a typical structure of a conventional touchscreen; [19] Fig. 2 is a view conceptually describing the touch location detection principle along with a cross-sectional structure of the touchscreen shown in Fig. 1; [20] Fig. 3 is a cross-sectional view simplifying part of the structure of a touch location detecting apparatus in accordance with an embodiment of the present invention; [21] Fig. 4 is a view conceptually illustrating the touch location detection principle and the overall configuration of the touch location detecting apparatus in accordance with the present invention; [22] Figs. 5 and 6 are views exemplifying the inner configuration of a charge-discharge characteristic measuring unit and the touch location detection principle; [23] Fig. 7 is a view illustrating a plurality of linear electrodes as an example of the structure of an electrode unit; [24] Fig. 8 is a view illustrating a plurality of point-type electrodes as another example of the structure of the electrode unit; [25] Fig. 9 is a view describing the principle of calculating the touch location especially when two point-type electrodes are arranged; [26] Fig. 10 is a block diagram illustrating the inner configuration of a user input device employing the touch location detecting apparatus in accordance with the present invention; [27] Fig. 11 is a view exemplifying a display screen that is controlled by using the user input device in accordance with the present invention; and [28] Fig. 12 is a view exemplifying the structure of a stylus pen that is applicable to the user input device in accordance with the present invention.

Best Mode for Carrying Out the Invention [29] Hereinafter, a touch location detecting apparatus and a user input device in accordance with the present invention will be described in detail with reference to the accompanying drawings. [30] Fig. 3 is a cross-sectional view showing the structure of a panel unit of a touch location detecting apparatus in accordance with the present invention. As shown in Fig. 3, the panel unit of the inventive touch location detecting apparatus includes a transparent conductive panel 310 formed on the front surface of a display screen of a display device 340 and supported by a transparent substrate 330, an electrode unit having a plurality of electrodes 311 and 312 formed on the transparent conductive panel 310, and a transparent insulating panel 320 provided to cover the front surface of the transparent conductive panel 310.

[31] The transparent insulating panel 320 functions as a surface for receiving a user's touch. The user can touch a desired location on the transparent insulating panel 320 formed over the front surface of the display screen by using a finger or stylus pen. Preferably, the transparent insulating panel 320 has a predetermined thickness and is formed of a material having a uniform dielectric constant. The transparent insulating panel 320 may be formed by stacking a plurality of insulating films where necessary.

[32] The transparent conductive panel 310 may be formed of a single transparent material having conductivity. However, in terms of durability and transparency, the transparent conductive panel 310 is preferably constructed by coating a transparent conductive material on one surface of a transparent substrate. Transparent conductive materials that can be used include transparent conductive oxides such as In O , SnO and ZnO, transparent conductive metal materials such as Au, Ag and Cu, transparent polymer compounds such as AGFA Orgacon™, and so on. Among these materials, especially, ITO (Indium Tin Oxide, In O :Sn) that is widely used in the semiconductor field is easily available and has good properties suitable for the present apparatus.

[33] To attain a stable touch location detection performance, the transparent conductive panel 310 has a uniform resistance component. The term "uniformity" used herein means uniformity that falls within a normally allowable error range.

[34] The electrodes 311 and 312 formed at a plurality of locations on the transparent conductive panel 310 are made of a conductive metal material such as Au, Ag, Cu or the like, and are electrically contacted with the surface coated with the transparent conductive material of the transparent conductive panel 310.

[35] The touch location detecting apparatus in accordance with the present invention is largely divided into a panel unit and a control unit. The above-described panel unit is connected to the control unit through the electrodes 311 and 312. The control unit serves to measure a signal required for detecting a touch location from the panel unit and calculate the touch location based on the measured signal.

[36] The present invention includes at least two embodiments, depending on the configuration of the control unit, as shown below.

[37] [38] (First Embodiment)

[39] Fig. 4 schematically illustrates the configuration of the panel unit and the control unit of a touch location detecting apparatus in accordance with a first embodiment of the present invention along with the principle of detecting a touch location of a user using the panel unit and the control unit. For convenience of explanation, only a single electrode 311 is depicted in Fig. 4.

[40] Fig. 4 exemplifies a case where a user's finger is touched on a touch location 350.

From a structural point of view, a uniform capacitance C is formed across a thickness of the transparent insulating panel 320 at the touch location 350, and a resistance R is formed through a path which extends from the electrode 311 to a position corresponding to the touch location 350. Further, there is formed an equivalent circuit at the touch location 350 by a user's body which is modeled into a grounded capacitance C . b

[41] The charge-discharge characteristic measuring unit 410 connected to the panel unit through the electrode 311 supplies an electric charge to the circuit modeled as described above, and measures a charge-discharge characteristic signal 411 indicating charge/discharge characteristics of the equivalent circuit obtained in response to the supplied electric charge.

[42] The measured charge-discharge characteristic signal 411 is input to a touch location calculating unit 420 and used to calculate the touch location 350. The touch location calculating unit 420 includes a distance information extracting unit 421 for extracting information 426 on a distance from the touch location 350 to the electrode 311 on the transparent conductive panel 310 with reference to the input charge-discharge characteristic signal 411, and a touch location information generating unit 422 for generating information representing the touch location 350 based on the distance information 426 extracted for of the respective plurality of electrodes 311 and 312. The information generated by the touch location information generating unit 422 is directly used as touch location information 427 for the control of the display screen, or input to a movement information extracting unit 430 for extraction of additional information.

[43] Fig. 5 illustrates a detailed configuration of the charge-discharge characteristic measuring unit 410 briefly mentioned above. As discussed above, if there is a user's touch at a specific location on the transparent insulating panel 320, the part connected to the charge-discharge characteristic measuring unit 410 through the electrode unit 311 is modeled as an equivalent circuit in which the resistance Rt and the capacitances C and C are connected in series to the ground. When the capacitances C and C are replaced by an equivalent capacitance of C ' = C DQ(C +C ), the equivalent circuit can be expressed as Rt and Ct' connected in series.

[44] Fig. 5 illustrates the inner configuration of the charge-discharge characteristic measuring unit 410 which is connected to the simplified equivalent circuit and measures the charge/discharge characteristics required for calculation of the touch location 350. The charge-discharge characteristic measuring unit 410 includes a capacitor 415 charged with an electric charge Q, a switch 416 for supplying the electric charge Q charged in the capacitor 415 to the equivalent circuit for the panel unit through the electrode 311, and a buffer 147 for measuring an electric potential at the electrode 311.

[45] When the switch 416 opened with the capacitor 415 being charged is closed at a time t , an electric potential v (t) measured through the buffer 417 changes with the

0 q passage of time, as shown in Fig. 6. That is, a charge redistribution is performed while the electric charge Q is discharged from the capacitor 415 to charge the equivalent capacitance C '. [46] If the buffer 417 is considered to be virtually opened due to a very high input impedance, the overall shape of the circuit shown in Fig. 5 becomes an RC circuit in which C , R and C ' are connected in series. Accordingly, the voltage v (t) across the q t t ° ^J q capacitor C is expressed by a function of time t as follows: [47] MathFigure 1

v_q(_,t)= V_f+i V₀- V_j)e ^τ [48] Here, V denotes an initial value of v (t), i.e., an electric potential value measured at

0 q t=t , at which the switch is closed, and V denotes a final value of v (t), i.e., a value of v

0 f q

(t) when the charge redistribution is completed, and the voltage across the capacitor C q q and the voltage across the capacitor C ' then becomes equal to each other. A time constant

T is expressed as: [49] MathFigure 2

C_aC_t'R_t τ~*,(C_g || C/)= « ' ;

[50] A curve for v (t) expressed as in Eq. (1) above is illustrated in Fig. 6. As shown in q Fig. 6, the charge-discharge characteristic measuring unit 410 transfers the value of an electric potential V , which is measured through the buffer 417 at a specific point of time t after the switch is closed at t=t , to the touch location calculating unit 420 as the

S 0 charge-discharge characteristic signal. At this time, ts must not exceed t when v (t) f q becomes equal to V . Further, in this case, the charge-discharge characteristic measuring unit 410 may include a timer circuit and a sample-and-hold circuit for sampling V at time t . [51] In accordance with another embodiment of the present invention, the charge- discharge characteristic measuring unit 410 can measure time t when v (t) becomes t q equal to a predetermined threshold voltage V that is set between V and V and transfer the measured value of t to the touch location calculating unit 420 as the charge- discharge characteristic signal. In this case, the charge-discharge characteristic measuring unit 410 may include a comparator for comparing the threshold voltage V and the measured voltage v (t) and a timer circuit for detecting the time t . q t

[52] For reference, when a finger is not touched, no path for discharging the charge stored in the capacitor C is formed, thus maintaining v (t)=V even after the switch q q 0

416 is closed. Therefore, while the charge-discharge characteristic signal 411 is used as information for calculating the touch location 350 when a user's touch is applied, it can be used as information for determining whether or not the user has touched. [53] The charge-discharge characteristic signal 411 measured by the above-explained method is applied to the distance information extracting unit 421. As mentioned above, the transparent conductive panel 310 is formed of a material having a uniform resistance component, and thus, the resistance R is proportional to the distance from the electrode 311 to the touch location 350. In addition, the capacitance C formed across the thickness of the transparent insulating panel 320 has a constant value known at the time of its design. Further, a possible range of the capacitance component C for b modeling the grounding by a human body is also known and does not change depending on the touch location 350. Thus, the effect by the common component C b can be eliminated by measuring the touch location 350 respectively through the electrodes 311 and 312 prepared at the opposite locations.

[54] Like this, the charge-discharge characteristic signal 411 is a function of the resistance R , namely, the distance from the electrode 311 to the touch location 350 as a parameter, and the correlation therebetween is known as discussed above. Therefore, the distance information extracting unit 421 is able to extract information on the distance from each of the electrodes 311 and 312 to the touch location 350 by referring to the charge-discharge characteristic correlation between the resistance Rt and the charge-discharge characteristic signal 411.

[55] Meanwhile, the charge-discharge characteristic measuring unit 410 may include a means for adjusting the quantity of the electric charge Q to be supplied. The supply electric charge adjusting means may include a switch for increasing/decreasing the capacitance C by opening/short-circuiting between a plurality of capacitors arranged in q parallel, and a register for storing information for controlling a switching operation by adjusting the state and opening/short-circuiting timings and so on of the switch. By means of the supply electric charge adjusting means, the performance of the touch location detecting apparatus can be optimized depending on the type of digital equipments to which the present touch location detecting apparatus is applied, the using environment of the digital equipment, the touch characteristics of a user and the like.

[56]

[57] (Second Embodiment)

[58] A touch location detecting apparatus in accordance with a second embodiment of the present invention includes a transient response measuring unit as a substitute for the charge-discharge characteristic measuring unit 410 shown in Fig. 4. The transient response measuring unit applies a voltage pulse of a predetermined level through the electrode 311, and measures a transient response signal for the applied voltage pulse. The measured transient response signal is input to the touch location calculating unit 420, and the touch location calculating unit 420 calculates a touch location 350 on the basis of the transient response signal of the present embodiment, instead of the charge- discharge characteristic signal of the first embodiment.

[59] The voltage pulse applied by the transient response measuring unit may have various shapes such as a step function having a rising or falling edge, a pulse in which a rising edge and/or a falling edge continuously appear with a predetermined duration, or a clock pulse in which a rising edge and a falling edge appear alternately.

[60] The transient response signal obtained in response to the applied voltage pulse reflects transient response characteristics using, as a parameter, the resistance R proportional to the distance from the touch location 350 to the electrode 311 on the transparent conductive panel. As the capacitances C and C ' are of known values, the q t touch location calculating unit 420 measures the distance from the electrode 311 to the touch location 350 based on the measured transient response signal, and calculates the touch location 350 on the basis of this distance.

[61] Meanwhile, the transient response measuring unit may include a means for adjusting the shape of a voltage pulse to be provided thereto or adjusting the length or level of the pulse. Such a pulse adjusting means may be provided with a delay circuit, a pulse counter, a register, and so on.

[62] Each of the charge-discharge characteristic measuring unit 410 of the first embodiment and the transient response measuring unit of the second embodiment may be constructed as a single-chip integrated circuit. According to this construction, mounting of the touch location detecting apparatus on small/lightweight digital equipments becomes facilitated.

[63] The second embodiment has been described, mainly concerning the differences from the first embodiment, and the parts not described here may be considered to be the same as the first embodiment or to have the corresponding configuration.

[64] Figs. 7, 8 and 9 illustrate substantial configurations of the plurality of electrodes 311 and 312 included in the electrode unit of the touch location detecting apparatus according to the first and the second embodiment as set forth above.

[65] The electrode unit shown in Fig. 7 includes a plurality of electrodes 711 to 714 arranged linearly on the outer edges of the transparent conductive panel 310. By means of the electrodes 711 to 714 so arranged linearly, it is possible to measure coordinates of the X-direction by the charge-discharge characteristic signal or transient response signal measured from the electrodes 711 and 712 respectively arranged on the left and the right edge. Also, it is possible to measure coordinates of the Y-direction by the charge-discharge characteristic signal or transient response signal measured from the electrodes 713 and 714 arranged on the upper- and the lower-side edge, respectively.

[66] In contrast, Fig. 8 illustrates a case where electrodes are arranged in a point form.

The electrode unit shown in Fig. 8 includes electrodes 811 to 814 arranged in a point form at each of a plurality of positions on the transparent conductive panel 310. It is possible to measure information on a distance from each of the point-type electrodes 811 to 814 to a touch location based on the charge-discharge characteristic signal 411 or transient response signal measured from the respective point- type electrodes 811 to 814. It is also possible to calculate the touch location 350 on the basis of the set of measured distance information, for example, using the principle of a triangulation method.

[67] Accordingly, although the number of point form electrodes 811 to 814 is preferably three or more, it is also possible to calculate the touch location 350 even if only two electrodes are arranged where necessary. Fig. 9 illustrates a case where the electrodes 811 and 812 are arranged one by one at the lower- left and the lower-right corner of the transparent conductive panel 310. In case the distances dl and d2 from each of the electrodes 811 and 812 to the touch location 350 are obtained by the distance information extracting unit 421, either Pa or Pb can be determined as the touch location 350. However, Pb is automatically ruled out as it is not within an area on the display screen, and Pa is determined as the touch location 350. In this manner, the touch location 350 can be calculated even if the number of electrodes is two by arranging the point- type electrodes 811 and 812 on the outer corners of the transparent conductive panel 310 and referring to the locations where the point form electrodes 811 and 812 are arranged when determining the touch location 350.

[68] By using the point-type electrodes 811 to 814 exemplified in Figs. 8 and 9, it becomes possible to freely arrange a large number of electrodes and thus precisely calculate the touch location 350.

[69] As seen from the configurations of the electrode unit respectively exemplified in

Figs. 7, 8 and 9, the touch location information generating unit 422 stores an algorithm for generating touch location information 427 based on information 426 on a distance from each of the electrodes 311 and 312 to the touch location 350 which is obtained by the distance information extracting unit 421. This algorithm is determined depending on the arrangement of the electrodes 311 and 312 of the electrode unit.

[70] As described above, the location information generating unit 422 requires the distance information 426 extracted for each of the plurality of electrodes 311 and 312 for calculation of the touch location 350. Therefore, the charge-discharge characteristic measuring unit 410 of the first embodiment performs the measurement of the charge- discharge characteristic signal 411 for, and the transient response measuring unit of the second embodiment performs the measurement of the transient response signal for each of the plurality of electrodes 311 and 312. At this time, it is preferred that the charge-discharge characteristic signal 411 or transient response signal is sequentially measured for each of the electrodes 311 and 312 in order to remove interference elements.

[71] Additionally, the charge-discharge characteristic measuring unit 410 and the transient response measuring unit can repeatedly measure the charge-discharge characteristic signal 411 and the transient response signal plural times at regular periods, respectively. The time series touch location information 427 generated based on the charge-discharge characteristic signal 411 or transient response signal measured repeatedly at regular periods for each of the electrodes 311 and 312 is input to the movement information extracting unit 430.

[72] The movement information extracting unit 430 extracts movement information 431 of the touch location 350 based on the set of touch location information 427 measured periodically. The movement information 431 contains movement direction information, movement speed information, pattern information and so on formed by movement, which are acquired when the touch location 350 is moved to several locations on the transparent insulating panel 320 in a state that a user maintains his/her touch thereon. The movement information 431 may be expressed in the form of a single vector or in the form of a vector sequence including a plurality of vectors in a given order.

[73] The movement information 431 so obtained can be utilized in various forms for control of the display screen along with the touch location information 427. Fig. 10 illustrates a user input device in which the touch location detecting apparatus according to the present invention is employed in the front surface portion of the display screen and which includes an input control unit 910 for extracting control information 911 for the display screen from the movement information 431 or touch location information 427.

[74] Fig. 11 exemplifies a display screen that is controlled by the input control unit 910.

In Fig. 11, a menu 1020, buttons 1011 to 1014, an input window 1030, a cursor 1040, etc. are illustrated as components of the display screen. First, the input control unit 910 detects a user's touch at a specific location based on the touch location information 427 input from the touch location information generating unit 422.

[75] In case of a user interface including the cursor 1040, the input control unit 910 may control the display screen so that the cursor 1040 is moved to the coordinate on the screen corresponding to the detected touch location 350. In case of a user interface without having a cursor 1040, the user input controls the menu 1020 or the buttons 1011 to 1014 positioned at the coordinate on the screen that corresponds to the touch location 350 are activated, and thus the contents of the menu 1020 can be displayed or the buttons 1011 to 1014 can be recognized as being clicked.

[76] Furthermore, the input control unit 910 is able to process such an input pattern separately from a general touch in case a touch is continuously detected for more than a given time without a change in the touch location 350. That is, the touch time information is utilized as additional input information.

[77] Meanwhile, in case the input window 1030 is activated by touching on a screen area within the input window 1030, the user can input a desired pattern in the area within the input window 1030. The input control unit 910 can display the user's input pattern in the input window 1030 by referring to the movement information 431. In this case, the input pattern can be utilized for character recognition and the like. Moreover, if a correspondence relation between a specific control operation and a specific input pattern is preset, the movement information 431 can be used as information for performing the corresponding control operation. For example, if an input pattern for drawing a circle under the state of being touched on a specific location is connected to the operation of displaying a popup menu on the corresponding location, the input control unit 910 can generate and output display screen control information 911 for displaying the popup menu at the touch location 350 on the screen when the movement information 431 representing such a movement pattern is inputted.

[78] If the touch location 350 has to be finely determined because the size of the display screen is small or the resolution is high, or if a movement pattern has to be finely inputted for graphic work, signature authentication, etc., a stylus pen can be used instead of a finger. Fig. 12 illustrates a stylus pen that is applicable to the user input device in accordance with the present invention.

[79] The stylus pen shown in Fig. 12 includes a touch portion 1110 to be touched on the transparent insulating panel 120 and a grip portion 1120 to be gripped by a user. At this time, the touch portion 1110 and the grip portion 1120 have to be formed of a conductive material and be electrically connected to each other. This is for forming the same equivalent circuit as having the touch location 350 grounded through a human body even if the stylus pen is used. Although Fig. 12 exemplifies the type in which the touch portion 1110 and the grip portion 1120 are connected through a conductor wire 1130 within the stylus pen, it should be noted that a stylus pen, manufactured by coating entire surface thereof with a conductive material such as metal, can be more generally used.

[80] As mentioned above and will be discussed below, the touch location detecting apparatus and the user input device according to the present invention would help fundamentally overcome the problems of damages to and degraded performance of the apparatus and the device that are caused by a pressure applied to the panel unit by a user's touch.

[81] In addition, according to the present invention, it is possible to minimize the phenomenon of degrading the definition of the display screen by the panel unit covering the front surface portion of the display screen.

[82] Further, in accordance with the touch location detection principle suggested by the present invention, a touch location can be precisely detected regardless of the operating environment of digital equipments, the properties of a user body, and any difference in touch characteristics.

[83] Moreover, the touch location detecting apparatus according to the present invention can be easily mounted on small/lightweight digital equipments, and accordingly, is applicable to a variety of equipments and fields.

[84] Besides, the touch location detecting apparatus according to the present invention can effectively calculate the touch location even when only two or three electrodes are provided on the transparent conductive panel.

[85] While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

[1] An apparatus for detecting a touch location of a user on a display screen, comprising: a transparent insulating panel, provided on a front surface portion of the display screen, for receiving the user's touch; a transparent conductive panel provided between the transparent insulating panel and the display screen and having a uniform resistance component; an electrode unit having a plurality of electrodes formed respectively at a plurality of locations on the transparent conductive panel; a charge-discharge characteristic measuring unit for measuring a charge- discharge characteristic signal indicating charge/discharge characteristics of an electric charge to be supplied through the electrode unit; and a touch location calculating unit for calculating the touch location on the transparent insulating panel based on the measured charge-discharge characteristic signal.

[2] The apparatus of claim 1, wherein the touch location calculating unit includes: a distance information extracting unit for extracting information on a distance from the touch location to the plurality of electrodes on the transparent conductive panel on the basis of the measured charge-discharge characteristic signal; and a touch location information generating unit for generating touch location information based on the distance information extracted for each of the plurality of electrodes.

[3] The apparatus of claim 2, wherein the distance information extracting unit extracts the distance information by referring to charge-discharge characteristic correlation between the charge-discharge characteristic signal and a resistance between the touch location and the location of each of the plurality of electrodes on the transparent conductive panel.

[4] The apparatus of claim 2, wherein the touch location information generating unit generates the touch location information from the distance information extracted for each of the plurality of electrodes.

[5] The apparatus of claim 1, wherein the charge-discharge characteristic measuring unit measures, as the charge-discharge characteristic signal, an electric potential measured from the electrode unit at a specific point of time after supplying the electric charge.

[6] The apparatus of claim 1 , wherein the charge-discharge characteristic measuring unit measures, as the charge-discharge characteristic signal, time information until an electric potential measured by the electrode unit reaches a preset threshold after supplying the electric charge.

[7] The apparatus of claim 1, wherein the charge-discharge characteristic measuring unit sequentially performs the measurement of the charge-discharge characteristic signal for the plurality of electrodes.

[8] The apparatus of claim 1, wherein the charge-discharge characteristic measuring unit repeats the measurement of the charge-discharge characteristic signal plural times at regular periods.

[9] The apparatus of claim 1, wherein the charge-discharge characteristic measuring unit includes a means for adjusting the quantity of the electric charge to be supplied.

[10] The apparatus of claim 1, wherein the charge-discharge characteristic measuring unit is constructed as a single-chip integrated circuit.

[11] An apparatus for detecting a touch location of a user on a display screen, comprising: a transparent insulating panel, provided on a front surface portion of the display screen, for receiving the user's touch; a transparent conductive panel provided between the transparent insulating panel and the display screen and having a uniform resistance component; an electrode unit including a plurality of electrodes formed respectively at a plurality of locations on the transparent conductive panel; a transient response measuring unit for applying a voltage pulse through the electrode unit and measuring a transient response signal for the applied voltage pulse; and a touch location calculating unit for calculating the touch location on the transparent insulating panel based on the measured transient response signal.

[12] The apparatus of claim 11, wherein the transient response measuring unit includes a means for adjusting at least one of a level, a length and a shape of the voltage pulse.

[13] The apparatus of claim 11, wherein the transient response measuring unit is constructed as a single-chip integrated circuit.

[14] The apparatus of claim 1 or 11, wherein the electrode unit includes a plurality of electrodes linearly arranged on the outer edges of the transparent conductive panel.

[15] The apparatus of claim 1 or 11, wherein the electrode unit includes a plurality of electrodes arranged in a point form at a plurality of locations on the transparent conductive panel.

[16] The apparatus of claim 15, wherein the number of electrodes arranged on the transparent conductive panel is two or three.

[17] The apparatus of claim 1 or 11, wherein the transparent conductive panel includes a coating film formed of any one of a transparent conductive metal, a transparent conductive oxide and a transparent conductive polymer compound.

[18] The apparatus of claim 1 or 11, further comprising: a movement information extracting unit for extracting movement information of the touch location based on a set of the touch location information generated repeatedly at regular periods.

[19] A user input device comprising an input control unit for extracting control information for a display screen from the touch location information detected by the touch location detecting apparatus of claim 1 or 11 that is provided on a front surface portion of the display screen.

[20] The user input device of claim 19, wherein the input control unit is provided with the function of moving a cursor to a coordinate on the screen that corresponds to the detected touch location information.

[21] The user input device of claim 19, wherein the input control unit activates a user input control positioned at a coordinate on the screen that corresponds to the detected touch location information.

[22] The user input device of claim 19, further comprising: a stylus pen having a grip portion gripped by a user and a touch portion for forming the touch location by being touched at an arbitrary location on the transparent insulating panel, wherein the grip portion and the touch portion are formed of conductive material and connected to each other.