Abstract:
An active touch system is provided, in which sensing electroding units in an array and two groups of intersecting control electrodes and detecting lines are disposed on a touch substrate, and the detecting lines are connected to sensing electrodings through active devices. The control electrodes are used to control on and off of the active devices, and the detecting lines are used to apply touch excitation signals to the sensing electrodings, and detect a leakage current of a sensing electroding to a finger or other touch object. A position of the finger or other touch object on the touch substrate is found by determining a sensing electroding unit generating the leakage current. The method of obtaining touch signals is improved in the hardware sensing stage, so that the judgment procedure after detection is greatly simplified, and the judgment of multi-point touch becomes easy and natural.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a touch screen, and more particularly to an active touch screen and a driving circuit thereof. 
     2. Related Art 
     Touch is the most important sensory perception of human beings, and is the most natural way in human-machine interaction. The touch screen thus emerges and has already been widely applied in personal computers, smart phones, public information, intelligent household appliances, industrial control, and other fields. In the current touch field, the resistive touch screen, photoelectric touch screen, ultrasonic touch screen, and planar capacitive touch screen are mainly developed, and in recently years, the projected capacitive touch screen is developed rapidly. 
     So far, the resistive touch screen is still the mainstream product in the market. However, due to the double-layer substrate structure of the resistive touch screen, when the touch screen and the display panel are laminated in use, the reflection of the touch screen may greatly affect the display performance such as brightness, contrast, and chroma, thus greatly degrading the display quality, and the increase of the backlight brightness of the display panel may cause higher power consumption. The analog resistive touch screen has the problem of positioning drift, and needs calibration from time to time. In addition, the electrode contact working mode of the resistive touch screen also reduces the service life of the touch screen. 
     The display quality of the infrared touch screen and the ultrasonic touch screen is not affected. However, the cost of the infrared touch screen and the ultrasonic touch screen is high, and the water drop and dust may impair the working reliability of the touch screen. Particularly, due to their complicated structures and high power consumption, the infrared touch screen and the ultrasonic touch screen generally cannot be applied in portable products. 
     The planar capacitive touch screen has a single-layer substrate structure, and thus when the touch screen and the display panel are laminated in use, the touch screen only has a small impact on the display quality. However, the planar capacitive touch screen also has the problem of positioning drift, and needs calibration from time to time. The water drop may also impair the working reliability of the touch screen. Particularly, due to its high power consumption and cost, the planar capacitive touch screen generally cannot be applied in portable products. 
     The projected capacitive touch screen may also have a single-layer substrate structure, and thus when the touch screen and the display panel are laminated in use, the touch screen only has a small impact on the display quality. However, the projected capacitive touch screen detects the position of the finger or other touch objects on the touch screen by measuring the influence of the finger or other touch objects on the coupling capacitance between the electrodes of the touch screen, that is, by measuring the influence of the finger or other touch objects on the charging/discharging of the electrodes of the touch screen. The positioning point is obtained through analog computation, and thus the projected capacitive touch screen is not a real digital touch screen. The distributed capacitance in the manufacturing and use environment may affect the working reliability of the touch screen, and the interference of the display driving signal and other electrical signals may influence the working of the touch screen, and the water drop may also impair the working reliability of the touch screen. In addition, the projected capacitive touch screen has a high requirement for the resistance of the detecting line, such that the detecting line of the projected capacitive touch screen laminated with the display panel in use needs to have not only a low electrical conductivity transparent electrode layer like ITO, but also a high electrical conductivity electrode layer like metal. Therefore, the manufacturing process is complicated, and the cost is high, especially for the large-sized and even ultra large-sized touch screens. 
     As iPhone and Windows 7 operating system have been launched in recent years, people are more interested in multi-point touch. Since each sensing line on a screen, no matter on a resistive touch screen or a capacitive touch screen, is directly connected to multiple sensing units, sensing units are not completely independent of each other. In order to recognize multiple touch points, compared with single-point touch, the scanning mode of detection becomes more complicated and much time is spent on detection, or the judgment procedure after detection becomes complicated and requires strong computing power and large storage space and also consumes a lot of time. By improving the touch screen directly and modifying the detection mode accordingly, the sensing units on the screen can be completely independent and multi-point touch will become easy and natural. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a touch screen having active devices, so that sensing units on the screen are completely independent. 
     The basic operating principle of the active touch system of the present invention is as follows. 
     Sensing electroding units in an array and two groups of intersecting control electrodes and detecting lines are disposed on a touch substrate, and the detecting lines are connected to sensing electrodings through active devices. The control electrodes are used to control on and off of the active devices, and the detecting lines are used to apply touch excitation signals to the sensing electrodings, and detect a leakage current of a sensing electroding to a touch object. When a human finger or other touch object approaches or contacts a sensing electroding unit, a coupling capacitance is formed between the finger or other touch object and the sensing electroding unit, and the touch excitation signal on the sensing electroding unit is leaked out partially through the coupling capacitance. The touch system circuit finds a detecting line with a maximum leakage current or a leakage current exceeding a threshold by detecting a change of a touch signal on each detecting line providing the touch excitation signal to the sensing electroding, and then determines the sensing electroding unit generating the leakage current according to the control electrode line turning on the active device at this time, so as to find a position of the finger or other touch object on the touch substrate. 
     A thin film field effect transistor, namely, thin film transistor (TFT), is a typical representative of active matrix devices, and in the TFT, a gate is connected to a scanning line in a horizontal direction, a source is connected to a data line in a vertical direction, and a drain is connected to a load electrode (herein, the drain and source are defined habitually, and the source level does not refer specially to the level of the source electrode, but refers to the smaller one between the levels of the source electrode and the drain electrode). The active device array arranged in an array enables each load electrode to be configured with a semiconductor switching device which can be gated by pulse, so that the load electrodes are independent of each other. 
     Thin film field effect transistors (TFTs) are grouped into two types: N-channel metal oxide semiconductor (NMOS) and P-channel metal oxide semiconductor (PMOS). Currently, most of TFTs employ an amorphous silicon (a-Si) process, in which a gate insulating layer is SiNx, which captures positive charge easily to form a channel in an a-Si semiconductor layer, the positive charge in SiNx is used to help attract electrons to form the channel, and thus the TFTs using the a-Si process are mostly of the NMOS type. The contents of the specification are described by taking NMOS type TFTs as a representative, and PMOS type TFTs can follow the same principle, and will not be illustrated separately. 
     The following technical solution is provided to solve the technical problems of the present invention. 
     An active touch system is provided, which includes a touch substrate and sensing lines, in which the sensing lines include sensing electrodings, control electrodes, and detecting lines, and the sensing lines are used for detecting a position of a finger of an operator or other touch object on the touch substrate; the touch substrate has active device units arranged in an array, sensing electroding units arranged in an array, and at least two groups of intersecting control electrodes and detecting lines, and each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof; and the sensing electrodings are connected to active devices, and the active devices are connected to the control electrodes and the detecting lines. 
     The following technical solutions are further provided to solve the technical problems of the present invention. 
     In a specific implementation of the present invention, the active device unit in the active device array has one or more active elements. 
     In a specific implementation of the present invention, the active device unit in the active device array is a two-terminal active device or a three-terminal active device. 
     In a specific implementation of the present invention, when the active device unit in the active device array is a two-terminal active device, the control electrode line is connected to the sensing electroding unit through a capacitor, and the sensing electroding unit is further connected to one terminal of the two-terminal active device unit; and the detecting line is connected to the other terminal of the two-terminal active device unit. 
     In a specific implementation of the present invention, when the active device unit in the active device array is a three-terminal active device, the control electrode line and the detecting line are respectively connected to two terminals of the three-terminal active device unit, and another terminal of the three-terminal active device unit is connected to the sensing electroding unit. 
     In a specific implementation of the present invention, the three-terminal active device array is a TFT array, the control electrode lines and the detecting lines are respectively connected to gates and sources of TFTs, and drains of the TFTs are connected to the sensing electroding units. 
     In a specific implementation of the present invention, a single layer or multiple layers of shielding electrodes are disposed on a different layer at all or a part of positions of the touch substrate having the detecting lines, and the shielding electrodes are isolated from the detecting lines and the active device array by insulators. 
     In a specific implementation of the present invention, a single layer or multiple layers of shielding electrodes are disposed on a different layer at positions of the touch substrate having the sensing electroding units, and the shielding electrodes are isolated from the sensing electroding array by insulating layers. 
     In a specific implementation of the present invention, the touch substrate is a flexible or rigid transparent substrate, and the sensing electroding units are transparent electrodes. 
     In a specific implementation of the present invention, the sensing electroding array is disposed on a touch surface or a non-touch surface of the touch substrate 
     In a specific implementation of the present invention, the control electrode lines or the detecting lines have fold lines, and two adjacent linear segments of the fold line form an angle ranging from 20° to 160° 
     In a specific implementation of the present invention, the active touch system shares the same substrate with a flat panel display screen. 
     In a specific implementation of the present invention, an active touch system includes a touch substrate, sensing lines, and a touch system circuit, in which the sensing lines include sensing electrodings, control electrodes, and detecting lines, the touch system circuit has a touch excitation source, a signal detection circuit, and a control circuit, and the sensing lines and the touch system circuit are used for detecting a position of a finger of an operator or other touch object on the touch substrate; the touch substrate has active device units arranged in an array, sensing electroding units arranged in an array, and at least two groups of intersecting control electrodes and detecting lines, each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof; the sensing electrodings are connected to active devices, the active devices are connected to the control electrodes and the detecting lines, the detecting lines are connected to the touch excitation source and the signal detection circuit in the touch system circuit, and the control electrodes are connected to the control circuit in the touch system circuit; the touch system circuit controls on or off of the active device units in the active device array through the control electrodes; and when a part of the active device units are in an on state, all or a part of the detecting lines are used to provide touch signals to the sensing electroding units, and detect changes of the touch signals on the detecting lines in communication with the sensing electroding units, so as to determine a position of a touch point. 
     In a specific implementation of the present invention, the touch signals output by the touch system circuit to the detecting lines in communication with the sensing electroding units are alternate current (AC) signals with a frequency of not less than 10 KHz. 
     In a specific implementation of the present invention, the touch system circuit detects at least one of amplitude, time, phase, frequency signal, and pulse number in detecting the change of the touch signal. 
     In a specific implementation of the present invention, the touch system circuit detects variance of the touch signal or a variation rate of the touch signal in detecting the change of the touch signal. 
     In a specific implementation of the present invention, the active device units in the active device array are two-terminal active devices, row electrodes serving as the control electrodes and column electrodes serving as the detecting line are respectively connected to two terminals of each active device unit in the two-terminal active device array, the sensing electroding units are connected to terminals of the two-terminal active device units connected to row electrode lines; the control circuit in the touch system circuit applies electrical signals to a part of electrode lines in the row electrodes so as to cause active devices connected thereto to be in the on state; and the detection circuit in the touch system circuit further applies touch signals to a part or all of electrode lines in the column electrodes and detects changes of the touch signals on the electrode lines. 
     In a specific implementation of the present invention, the active device units in the active device array are TFTs, row electrodes serving as the control electrodes and column electrodes serving as the detecting line are respectively connected to gates and sources of the TFTs, the sensing electroding units are connected to drains of the TFTs; the control circuit in the touch system circuit applies electrical signals to a part of electrode lines in the row electrodes so as to cause TFTs connected thereto to be in the on state; and the detection circuit in the touch system circuit further applies touch signals to a part or all of electrode lines in the column electrodes and detects changes of the touch signals on the electrode lines. 
     In a specific implementation of the present invention, the touch system circuit positions a touched column electrode line by taking a column electrode line with a change of a touch signal reaching a touch positioning condition detected by the detection circuit as the touched column electrode line; the touch system circuit positions a touched row electrode line by taking a row electrode line with an active device caused by the control circuit to be in the on state upon detecting the column electrode line with the change of the touch signal reaching the touch positioning condition as the touched row electrode line; and a touched point on the touch substrate is a cross position between the touched row electrode line and the touched column electrode line. 
     In a specific implementation of the present invention, the touch positioning condition is: variance of a touch signal or a variation rate of a touch signal is maximum, or variance of a touch signal or a variation rate of a touch signal exceeds a set threshold, or variance of a touch signal or a variation rate of a touch signal is maximum and exceeds a set threshold. 
     In a specific implementation of the present invention, the touch system circuit determines touched positions between the column electrode lines through calculation by detecting a difference between the changes of the touch signals on the column electrode lines; and the touch system circuit determines touched positions between the row electrode lines through calculation by detecting a difference between changes of the touch signal on the same column electrode line at different time points. 
     In a specific implementation of the present invention, the touch system circuit applies the electrical signals to a part of electrode lines in the row electrodes so as to cause the active devices connected thereto to be in the on state by scanning; and the touch system circuit applies the touch signals to all or a part of electrode lines in the column electrodes and detects changes of the touch signals on the electrode lines by scanning or simultaneously. 
     In a specific implementation of the present invention, the touch signal flows in a closed loop, the touch system circuit also selects a part of electrode lines of the touch substrate as touch return-loop electrodes while selecting a part of electrodes as touch excitation electrodes; or touch return-loop electrodes are disposed on a housing of the active touch system; the touch return-loop electrodes refer to sensing lines, when touch signals are applied to touch detecting lines and changes of touch signals flowing there-through are detected, in communication with a second output end of the touch excitation source or another touch excitation source for providing return paths for the touch signals on the detecting lines; and changes of the touch signals on the detecting lines in communication with the sensing electroding units are detected, so as to determine a position of a touch point 
     In a specific implementation of the present invention, the touch return-loop electrodes refer to a part or all of electrode lines not intersecting the touch detecting lines, or a part or all of electrode lines intersecting the touch detecting lines, or a part or all of electrode lines intersecting and not intersecting the touch detecting lines. 
     In a specific implementation of the present invention, the touch return-loop electrodes not intersecting the touch detecting lines are electrode lines adjacent to the touch detecting lines on one or both sides thereof. 
     Compared with the prior art, the present invention has the following beneficial effects. 
     In the present invention, active devices are introduced into a touch screen, so that sensing electroding units on the screen can respectively sense the touch of a touch object completely independently. The hardware sensing stage in the front end of the touch system is improved, the detection of the touched position is digitalized in space, so that the source of the touch signal achieves the precision up to each sensing electroding unit. According to magnitudes of signals of adjacent sensing electroding units or according to the distribution of signals in the area of sensing electroding units having touch signals, the precision of positioning a touched position can be improved so that even a fine position between adjacent sensing electroding units can be positioned. 
     By introducing active devices into the touch screen and improving the method of obtaining touch signals in the hardware sensing stage of the touch system, the judgment procedure after detection is greatly simplified, so that post-processing chip resources can be saved significantly, the detecting becomes quicker and more reliable, and the overall cost may be lower. 
     By introducing active devices into the touch screen, the sensing electroding units on the screen can operate completely independently, the judgment of multi-point touch is realized, and multi-point touch becomes easy and natural. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view illustrating electrical connection of a first embodiment in the present invention; 
         FIG. 2  is a schematic view illustrating electrical connection of a second embodiment in the present invention; 
         FIG. 3  is a schematic view illustrating electrical connection of a third embodiment in the present invention; 
         FIG. 4  is a schematic view illustrating electrical connection of a fourth embodiment in the present invention; 
         FIG. 5  is a schematic view illustrating electrical connection of a fifth embodiment in the present invention; 
         FIG. 6  is a schematic view illustrating electrical connection of a sixth embodiment in the present invention; 
         FIG. 7  is a schematic view illustrating electrical connection of a seventh embodiment in the present invention; and 
         FIG. 8  is a schematic view illustrating electrical connection of an eighth embodiment in the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
     An active touch system  100  as shown in  FIG. 1  includes a touch substrate  110 , an active device array  120 , sensing lines, and a touch system circuit  140 . The three-terminal active device array  120  and the sensing line are disposed on the touch substrate  110 . The sensing lines include a sensing electroding array  131  and two groups of intersecting row control electrodes  132  and column detecting lines  133 . Each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. The touch substrate  110  is a transparent substrate, each sensing electroding unit of the sensing electroding array  131  is a transparent indium tin oxide (ITO) electrode, the sensing electroding array  131 , the row control electrodes  132 , and the column detecting lines  133  are all disposed on a non-touch surface of the touch substrate  110  not facing users, and an insulating and protective outer layer is further disposed on the sensing electroding array  131 , the row control electrodes  132 , and the column detecting lines  133 . The touch system circuit  140  has a touch excitation source  141 , a signal detection circuit  142 , and a control circuit  143 . 
     Each control electrode line and each detecting line of the control electrodes  132  and the detecting lines  133  are respectively connected to two terminals of each active device unit of the three-terminal active device array  120 ; each sensing electroding unit of the sensing electroding array  131  is respectively connected to another terminal of each active device unit; the detecting lines  133  are connected to the touch excitation source  141  and the signal detection circuit  142  in the touch system circuit  140 ; and the control electrodes  132  are connected to the control circuit  143  in the touch system circuit  140 . 
     The touch excitation source  141  of the touch system circuit  140  applies a touch signal to each detecting line of the detecting lines  133  simultaneously. The control circuit  143  of the touch system circuit  140  outputs a turn-on signal to each control electrode line of the control electrodes  132  row by row by scanning, active device units connected to control electrode lines with the turn-on signals are in an on state, and active device units connected to control electrode lines without the turn-on signals are in an off state. As the control circuit  143  causes active device units on each row of control electrode lines to be in the on state, the touch signals on the detecting lines flow into sensing electroding units connected to the row of control electrode lines through the active device units; the signal detection circuit  142  of the touch system circuit  140  detects a change of the touch signal on each detecting line simultaneously or column by column. In this way, as the control circuit  143  outputs the turn-on signal to each control electrode line row by row, the signal detection circuit  142  detects a change of the touch signals on the sensing electroding units connected to the row of control electrode lines through the active device units row by row. 
     When a finger of an operator or other touch object approaches or contacts a sensing electroding unit, a coupling capacitance is formed between the finger or other touch object and the sensing electroding unit, and the touch signal on the sensing electroding unit is leaked out partially through the coupling capacitance; the signal detection circuit  142  can find a detecting line with a maximum leakage current or with a leakage current exceeding a threshold by detecting the change of the touch signal on each detecting line applying the touch signal to the sensing electroding unit; and then according to the control electrode line turning on the active device at this time, the sensing electroding unit generating a leakage current can be determined, so as to find a position of the finger or other touch object on the touch substrate  110 . Thus, the active touch system  100  becomes a touch system capable of detecting the position of a touch point. 
     When multiple fingers of an operator or fingers of multiple operators respectively touch multiple positions of the touch substrate  110 , the signal detection circuit  142  detects that the changes of touch signals exceed a threshold on multiple detecting lines at multiple time points, that is, detects that leakage currents of multiple sensing electroding units exceed a threshold, so as to find the respective positions of the multiple fingers on the touch substrate  110 . Thus, the active touch system  100  becomes a touch system capable of recognizing multiple touch points. 
     Second Embodiment 
     An active touch system  200  as shown in  FIG. 2  includes a touch substrate  210 , a thin film transistor (TFT) array  220 , sensing lines, and a touch system circuit  240 . The TFT array  220  and the sensing lines are disposed on the touch substrate  210 . The sensing lines include a sensing electroding array  231  and two groups of intersecting row control electrodes  232  and column detecting lines  233 , and each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. The touch substrate  210  is a transparent substrate, each sensing electroding unit of the sensing electroding array  231  is a transparent ITO electrode, the sensing electroding array  231 , the row control electrodes  232 , and the column detecting lines  233  are all disposed on a touch surface of the touch substrate  210  facing users, and an insulating and protective outer layer is further disposed on the sensing electroding array  231 , the row control electrodes  232 , and the column detecting lines  233 . The touch system circuit  240  has a touch excitation source  241 , a signal detection circuit  242 , and a control circuit  243 . 
     Each control electrode line and each detecting line of the control electrodes  232  and the detecting lines  233  are respectively connected to a gate and a source of each TFT of the TFT array  220 ; each sensing electroding unit of the sensing electroding array  231  is respectively connected to a drain of each TFT; the detecting lines  233  are connected to the touch excitation source  241  and the signal detection circuit  242  in the touch system circuit  240 ; and the control electrodes  232  are connected to the control circuit  243  in the touch system circuit  240 . 
     The touch excitation source  241  of the touch system circuit  240  applies a touch signal to each detecting line of the detecting lines  233  simultaneously. The control circuit  243  of the touch system circuit  240  outputs a turn-on signal to each control electrode line of the control electrodes  232  row by row by scanning, TFTs connected to control electrode lines with the turn-on signals are in an on state, and TFTs connected to control electrode lines without the turn-on signals are in an off state. As the control circuit  243  causes TFTs on each row of control electrode lines to be in the on state, the touch signals on the detecting lines flow into sensing electroding units connected to the row of control electrode lines through the TFTs; and the signal detection circuit  242  of the touch system circuit  240  detects a change of the touch signal on each detecting line simultaneously or column by column. In this way, as the control circuit  243  outputs the turn-on signal to each control electrode line row by row, the signal detection circuit  242  detects a change of touch signals on the sensing electroding units connected to the row of control electrode lines through the TFTs row by row. 
     When a finger of an operator or other touch object approaches or contacts a sensing electroding unit, a coupling capacitance is formed between the finger or other touch object and the sensing electroding unit, and the touch signal on the sensing electroding unit is leaked out partially through the coupling capacitance; the signal detection circuit  242  can find a detecting line with a maximum leakage current or with a leakage current exceeding a threshold by detecting the change of the touch signal on each detecting line applying the touch signal to the sensing electroding; and then according to the control electrode line turning on the TFT at this time, the sensing electroding unit generating a leakage current can be determined, so as to find a position of the finger or other touch object on the touch substrate  210 . Thus, the active touch system  200  becomes a touch system capable of detecting the position of a touch point. 
     When multiple fingers of an operator or fingers of multiple operators respectively touch multiple positions of the touch substrate  210 , the signal detection circuit  242  detects that changes of touch signals exceed a threshold on multiple detecting lines at multiple time points, that is, detects that leakage currents of multiple sensing electroding units exceeds a threshold, so as to find the respective positions of the multiple fingers on the touch substrate  210 . Thus, the active touch system  200  becomes a touch system capable of recognizing multiple touch points. 
     Third Embodiment 
     An active touch system  300  as shown in  FIG. 3  includes a touch substrate  310 , an active device array  320 , sensing lines, and a touch system circuit  340 . The two-terminal active device array  320  and the sensing lines are disposed on the touch substrate  310 . The sensing lines include a sensing electroding array  331  and two groups of intersecting row control electrodes  332  and column detecting lines  333 . Each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. The touch substrate  310  is a flexible transparent substrate, each sensing electroding unit of the sensing electroding array  331  is a transparent ITO electrode, the sensing electroding array  331 , the row control electrodes  332 , and the column detecting lines  333  are all disposed on a non-touch surface of the touch substrate  310  not facing users. The touch system circuit  340  has a touch excitation source  341 , a signal detection circuit  342 , and a control circuit  343 . 
     Each control electrode line of the control electrodes  332  is respectively connected to each sensing electroding unit of the sensing electroding array  331  through a capacitor, and each sensing electroding unit is further respectively connected to one terminal of each active device unit of the two-terminal active device array  320 ; each detecting line of the detecting lines  333  is respectively connected to the other terminal of each active device unit of the two-terminal active device array  320 ; the detecting lines  333  are connected to the touch excitation source  341  and the signal detection circuit  342  in the touch system circuit  340 ; and the control electrodes  332  are connected to the control circuit  343  in the touch system circuit  340 . 
     The touch excitation source  341  of the touch system circuit  340  applies a touch signal to each detecting line of the detecting lines  333  simultaneously. The control circuit  343  of the touch system circuit  340  outputs a turn-on signal to each control electrode line of the control electrodes  332  row by row by scanning, the turn-on signals causes active device units connected to control electrode lines with the turn-on signals through the capacitors and the sensing electroding units to be in an on state, and active device units connected to control electrode lines without the turn-on signals through the capacitors and the sensing electroding units to be in an off state. As the control circuit  343  causes active device units on each row of control electrode lines to be in the on state, the touch signals on the detecting lines flow into sensing electroding units connected to the row of control electrode lines; the signal detection circuit  342  of the touch system circuit  340  detects a change of the touch signal on each detecting line simultaneously or column by column. In this way, as the control circuit  343  outputs the turn-on signal to each control electrode line row by row, the signal detection circuit  342  detects a change of the touch signals on the sensing electroding units connected to the row of control electrode lines row by row. 
     When a finger of an operator or other touch object approaches or contacts a sensing electroding unit, a coupling capacitance is formed between the finger or other touch object and the sensing electroding unit, and the touch signal on the sensing electroding unit is leaked out partially through the coupling capacitance; the signal detection circuit  342  can find a detecting line with a maximum leakage current or with a leakage current exceeding a threshold by detecting the change of the touch signal on each detecting line applying the touch signal to the sensing electroding unit; and then according to the control electrode line turning on the active device at this time, the sensing electroding unit generating a leakage current can be determined, so as to find a position of the finger or other touch object on the touch substrate  310 . Thus, the active touch system  300  becomes a touch system capable of detecting the position of a touch point. 
     When multiple fingers of an operator or fingers of multiple operators respectively touch multiple positions of the touch substrate  310 , the signal detection circuit  342  detects that the changes of touch signals exceed a threshold on multiple detecting lines at multiple time points, that is, detects that leakage currents of multiple sensing electroding units exceed a threshold, so as to find the respective positions of the multiple fingers on the touch substrate  310 . Thus, the active touch system  300  becomes a touch system capable of recognizing multiple touch points. 
     Fourth Embodiment 
     An active touch system  400  as shown in  FIG. 4  includes a touch substrate  410 , an active device array  420 , sensing lines, and a touch system circuit  440 . The active device unit array  420  and the sensing lines are disposed on the touch substrate  410 . Each active device unit is formed by connecting a diode and a capacitor in series. The sensing lines include a sensing electroding array  431  and two groups of intersecting row control electrodes  432  and column detecting lines  433 . Each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. The touch substrate  410  is a flexible transparent substrate, each sensing electroding unit of the sensing electroding array  431  is a transparent ITO electrode, the sensing electroding array  431 , the row control electrodes  432 , and the column detecting lines  433  are all disposed on a non-touch surface of the touch substrate  410  not facing users. The touch system circuit  440  has a touch excitation source  441 , a signal detection circuit  442 , and a control circuit  443 . 
     Each control electrode line and each detecting line of the control electrodes  432  and the detecting lines  433  are respectively connected to two terminals of each diode-capacitor series connection unit of the active device unit array  420 ; each sensing electroding unit of the sensing electroding array  431  is respectively connected to a connection point between each diode and capacitor; the detecting lines  433  are connected to the touch excitation source  441  and the signal detection circuit  442  in the touch system circuit  440 ; and the control electrodes  432  are connected to the control circuit  443  in the touch system circuit  440 . 
     The touch excitation source  441  of the touch system circuit  440  applies a touch signal to each detecting line of the detecting lines  433  simultaneously. The control circuit  443  of the touch system circuit  440  outputs a turn-on signal to each control electrode line of the control electrodes  432  row by row by scanning, diode-capacitor series connection units connected to control electrode lines with the turn-on signals are in an on state, and diode-capacitor series connection unit units connected to control electrode lines without the turn-on signals are in an off state. As the control circuit  443  causes active device units on each row of control electrode lines to be in the on state, the touch signals on the detecting lines flow into sensing electroding units connected to the row of control electrode lines; the signal detection circuit  442  of the touch system circuit  440  detects a change of the touch signal on each detecting line simultaneously or column by column. In this way, as the control circuit  443  outputs the turn-on signal to each control electrode line row by row, the signal detection circuit  442  detects a change of the touch signals on the sensing electroding units connected to the row of control electrode lines. 
     When a finger of an operator or other touch object approaches or contacts a sensing electroding unit, a coupling capacitance is formed between the finger or other touch object and the sensing electroding unit, and the touch signal on the sensing electroding unit is leaked out partially through the coupling capacitance; the signal detection circuit  442  can find a detecting line with a maximum leakage current or with a leakage current exceeding a threshold by detecting the change of the touch signal on each detecting line applying the touch signal to the sensing electroding unit; and then according to the control electrode line turning on the active device unit at this time, the sensing electroding unit generating a leakage current can be determined, so as to find a position of the finger or other touch object on the touch substrate  410 . Thus, the active touch system  400  becomes a touch system capable of detecting the position of a touch point. 
     When multiple fingers of an operator or fingers of multiple operators respectively touch multiple positions of the touch substrate  410 , the signal detection circuit  442  detects that the changes of touch signals exceed a threshold on multiple detecting lines at multiple time points, that is, detects that leakages current of multiple sensing electroding units exceed a threshold, so as to find the respective positions of the multiple fingers on the touch substrate  410 . Thus, the active touch system  400  becomes a touch system capable of recognizing multiple touch points. 
     Fifth Embodiment 
     An active touch system  500  as shown in  FIG. 5  includes a touch substrate  510 , a TFT array  520 , sensing lines, a touch system circuit  540 , and a display screen. The TFT array  520  and the sensing lines are disposed on the touch substrate  510 . The sensing lines include a sensing electroding array  531  and two groups of intersecting row control electrodes  532  and column detecting lines  533 , and each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. Linear shielding electrodes  534  are disposed on a different layer of the touch substrate  510  facing users at positions of all the column detecting lines  533  to prevent the interaction between a touch object and the detecting lines  533 ; planar shielding electrodes  535  are disposed on a different layer of the touch substrate  510  not facing users to prevent the influence of an electrical signal in the display screen on touch signals on the sensing electroding array  531  and the detecting lines  533 ; and the shielding electrodes  534  and  535  are isolated from the detecting lines  533 , the control electrodes  532 , and the TFT array  520  by insulating layers. The touch substrate  510  is a substrate shared with the display screen, each sensing electroding unit of the sensing electroding array  531  is a transparent ITO electrode, the sensing electroding array  531 , the row control electrodes  532 , and the column detecting lines  533  are all disposed on a touch surface of the touch substrate  510  facing users, and an insulating and protective outer layer is further disposed on the sensing electroding array  531 , the row control electrodes  532 , and the column detecting lines  533 . The touch system circuit  540  has a touch excitation source  541 , a signal detection circuit  542 , and a control circuit  543 . 
     Each control electrode line and each detecting line of the control electrodes  532  and the detecting lines  533  are respectively connected to a gate and a source of each TFT of the TFT array  520 ; each sensing electroding unit of the sensing electroding array  531  is respectively connected to a drain of each TFT; the detecting lines  533  are connected to the touch excitation source  541  and the signal detection circuit  542  in the touch system circuit  540 ; the control electrodes  532  are connected to the control circuit  543  in the touch system circuit  540 ; and the shielding electrodes  534  and  535  are in communication with each other and are connected to a ground terminal of the touch system circuit  540 . 
     The touch excitation source  541  of the touch system circuit  540  applies a touch signal to each detecting line of the detecting lines  533  simultaneously. The control circuit  543  of the touch system circuit  540  outputs a turn-on signal to each control electrode line of the control electrodes  532  row by row by scanning, TFTs connected to control electrode lines with the turn-on signals are in an on state, and TFTs connected to control electrode lines without the turn-on signals are in an off state. As the control circuit  543  causes TFTs on each row of control electrode lines to be in the on state, the touch signals on the detecting lines flow into sensing electroding units connected to the row of control electrode lines through the TFTs; and the signal detection circuit  542  of the touch system circuit  540  detects a change of the touch signal on each detecting line simultaneously or column by column. In this way, as the control circuit  543  outputs the turn-on signal to each control electrode line row by row, the signal detection circuit  542  detects a change of touch signals on the sensing electroding units connected to the row of control electrode lines through the TFTs row by row. 
     When a finger of an operator or other touch object approaches or contacts a sensing electroding unit, a coupling capacitance is formed between the finger or other touch object and the sensing electroding unit, the touch signal on the sensing electroding unit is leaked out partially through the coupling capacitance; since the shielding electrodes  534  and  535  are disposed, the coupling capacitance resulting in a leakage current is not generated between the finger or other touch object and the detecting lines  533 , and the electrical signal in the display does not influence the touch signals on the sensing electroding array  531  and the detecting lines  533 . The signal detection circuit  542  can find a detecting line with a maximum leakage current or with a leakage current exceeding a threshold by detecting the change of the touch signal on each detecting line applying the touch signal to the sensing electroding unit; and then according to the control electrode line turning on the TFT at this time, the sensing electroding unit generating a leakage current can be determined, so as to find a position of the finger or other touch object on the touch substrate  510 . Thus, the active touch system  500  becomes a touch system capable of detecting the position of a touch point. 
     When multiple fingers of an operator or fingers of multiple operators respectively touch multiple positions of the touch substrate  510 , the signal detection circuit  542  detects that the changes of touch signals exceed a threshold on multiple detecting lines at multiple time points, that is, detects that leakage currents of multiple sensing electroding units exceed a threshold, so as to find the respective positions of the multiple fingers on the touch substrate  510 . Thus, the active touch system  500  becomes a touch system capable of recognizing multiple touch points. 
     Sixth Embodiment 
     An active touch system  600  as shown in  FIG. 6  includes a touch substrate  610 , a TFT array  620 , and sensing lines. The TFT array  620  and the sensing lines are disposed on the touch substrate  610 . The sensing lines include a sensing electroding array  631  and two groups of intersecting row control electrodes  632  and column detecting lines  633 , and each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. The touch substrate  610  is a transparent substrate, each sensing electroding unit of the sensing electroding array  631  is a transparent ITO electrode, and the row control electrodes  632  and the column detecting lines  633  are non-transparent metal electrode lines. 
     In order to prevent the influence of the non-transparent row electrode lines and column electrode lines and edges of the transparent sensing electrodings on the display effect when the active touch screen  600  and the display screen are stacked in use, the row electrode lines and the column electrode lines are fold lines in an effective touch area, two adjacent linear segments of the fold line form an angle ranging from 20° to 160°, and the row electrode lines and the column electrode lines intersect without overlapping; and the shape of the edge of the transparent sensing electroding units is a polygon enclosed by two adjacent row electrode lines and two adjacent column electrode lines. The row control electrodes  632  and the column detecting lines  633  are connected through the TFT array  620  and the sensing electroding array  631  at intersections thereof. When the active touch screen  600  is used in combination with the display screen, inclined line segments in the non-transparent row electrodes  632  and the column electrodes  633  do not form diffraction fringes with non-transparent display row and column electrodes in the display screen; and edges of the fold lines of the transparent sensing electrodings  631  do not form interference fringes with transparent display pixel electrodes in the display screen, so as to avoid the influence on the display quality as much as possible. 
     Seventh Embodiment 
     An active touch system  700  as shown in  FIG. 7  includes a touch substrate  710 , an active device array  720 , sensing lines, and a touch system circuit  740 . The three-terminal active device array  720  and the sensing lines are disposed on the touch substrate  710 . The sensing lines include a sensing electroding array  731  and two groups of intersecting row control electrodes  732  and column detecting lines  733 . Each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. The touch substrate  710  is a transparent substrate, each sensing electroding unit of the sensing electroding array  731  is a transparent ITO electrode, the sensing electroding array  731 , the row control electrodes  732 , and the column detecting lines  733  are all disposed on a non-touch surface of the touch substrate  710  not facing users, and an insulating and protective outer layer is further disposed on the sensing electroding array  731 , the row control electrodes  732 , and the column detecting lines  733 . The touch system circuit  740  has a touch excitation source  741 , a signal detection circuit  742 , and a control circuit  743 . The touch excitation source  741  has a first output end  7411  and a second output end  7412 , the signal detection circuit  742  includes a touch sampling element  7421  and a remaining circuit  7422  of the detection circuit formed by circuits such as a buffer, a differential amplifier, a data convert channel, and a data processing and timing controller. 
     Each control electrode line and each detecting line of the control electrodes  732  and the detecting lines  733  are respectively connected to two terminals of each active device unit of the three-terminal active device array  720 ; each sensing electroding unit of the sensing electroding array  731  is respectively connected to another terminal of each active device unit; an electrode line  733   i  in the detecting lines  733  is connected to the first output end  7411  of the touch excitation source through the touch sampling element  7421 , electrode lines  733   i− 1 and  733   i+ 1 in the detecting lines  733  are connected to the second output end  7412  in the touch excitation source, and other electrode lines in the detecting lines  733  are also connected to the first output end  7411  of the touch excitation source, and the first output end  7411  and the second output end  7412  of the touch excitation source are output and input ports for signal return in the same touch excitation source. 
     The touch excitation source  741  of the touch system circuit  740  applies a touch signal to each detecting line of the detecting lines  733  simultaneously. The control circuit  743  of the touch system circuit  740  outputs a turn-on signal to each control electrode line of the control electrodes  732  row by row by scanning, active device units connected to control electrode lines with the turn-on signals are in an on state, and active device units connected to control electrode lines without the turn-on signals are in an off state. As the control circuit  743  causes active device units on each row of control electrode lines to be in the on state, the touch signals on the detecting lines flow into sensing electroding units connected to the row of control electrode lines through the active device units. A coupling capacitance C i−1  is formed between a sensing electroding unit  731   ji  and a sensing electroding unit  731   ji− 1, and a coupling capacitance C i+1  is formed between the sensing electroding unit  731   ji  and a sensing electroding unit  731   ji+ 1; the touch signal forms a closed loop between the touch excitation source  741 , the detecting line  733   i , the sensing electroding unit  731   ji , the coupling capacitance C i−1 , the sensing electroding unit  731   ji− 1, and the detecting line  733   i −1, and also forms a closed loop between the touch excitation source  741 , the detecting line  733   i , the sensing electroding unit  731   ji , the coupling capacitance C i−1 , the sensing electroding unit  731   ji+ 1, and the detecting line  733   i+ 1; the touch signal flowing out of the first output end  7411  of the touch excitation source  741  flows into the detecting line  733   i  through the touch sampling element  7421 , respectively flows into the sensing electroding unit  731   ji− 1 and the sensing electroding unit  731   ji+ 1 through the coupling capacitances C i−1  and C i+1 , and then flows back to the second output end  7412  of the touch excitation source  741  through the detecting lines  733   i− 1 and  733   i+ 1, so that the touch signal flows in a closed touch loop. 
     When a human finger as a touch object approaches or contacts the detecting line  733   i , since the finger has a certain width, the sensing electroding unit  731   ji , the sensing electroding unit  731   ji −1, and the sensing electroding unit  731   ji  are touched at the same time. The dielectric coefficient of the human body is far greater than that of air, so that the values of the coupling capacitances C i−1  and C i+1  increase and the reactance thereof decreases, and the current of the touch signal on the touch loop increases accordingly. When the finger approaches or contacts positions of detecting lines other than  733   i ,  733   i− 1, and  733   i+ 1, although the coupling capacitances between the detecting lines, between the sensing electroding units, and between the sensing electroding unit and the detecting line are changed, since output ends of the touch excitation source  741  in communication with the electrodes are the same output end  7411 , the change of the current in the touch signal flowing through the touch sampling element  7421  is very small. 
     The signal detection circuit  742  can find a detecting line with a maximum current change or with a current change exceeding a threshold by detecting the change of the touch signal on each detecting line applying the touch signal to the sensing electroding unit; and then according to the control electrode line turning on the active device at this time, the touched sensing electroding unit can be determined, so as to find a position of the finger or other touch object on the touch substrate  710 . Thus, the active touch system  700  becomes a touch system capable of detecting the position of a touch point. 
     The detecting lines may also be divided into multiple areas, and touch excitation signals may be added in different areas according to the same principle as above and detection may be performed, so as to enhance the speed of touch detection. When multiple fingers of an operator or fingers of multiple operators respectively touch multiple positions of the touch substrate  710 , the signal detection circuit  742  detects that the changes of touch signals exceed a threshold on multiple detecting lines at multiple time points, that is, detects that current changes of multiple sensing electroding units exceed a threshold, so as to find the respective positions of the multiple fingers on the touch substrate  710 . Thus, the active touch system  700  becomes a touch system capable of recognizing multiple touch points. 
     Eighth Embodiment 
     An active touch system  800  as shown in  FIG. 8  includes a touch substrate  810 , a TFT array  820 , sensing lines, and a touch system circuit  840 . The TFT array  820  and the sensing lines are disposed on the touch substrate  810 . The sensing lines include a sensing electroding array  831  and two groups of intersecting row control electrodes  832  and column detecting lines  833 . Each control electrode line and each detecting line are isolated by an insulating layer at an intersection thereof. The touch substrate  810  is a transparent substrate, each sensing electroding unit of the sensing electroding array  831  is a transparent ITO electrode, the sensing electroding array  831 , the row control electrodes  832 , and the column detecting lines  833  are all disposed on a touch surface of the touch substrate  810  facing users, and an insulating and protective outer layer is further disposed on the sensing electroding array  831 , the row control electrodes  832 , and the column detecting lines  833 . The touch system circuit  840  has a touch excitation source  841 , a signal detection circuit  842 , and a control circuit  843 . The touch excitation source  841  has a first output end  8411  and a second output end  8412  of touch signals, the signal detection circuit  842  has a touch sampling element  8421  and circuits such as a buffer, a differential amplifier, a data convert channel, and a data processing and timing controller. The active touch system has a housing  850 . 
     Each control electrode line and each detecting line of the control electrodes  832  and the detecting lines  833  are respectively connected to a gate and a source of each TFT of the TFT array  820 ; each sensing electroding unit of the sensing electroding array  831  is respectively connected to a drain of each TFT; the detecting lines  833  are connected to the touch excitation source  841  and the signal detection circuit  842  in the touch system circuit  840 ; the control electrodes  832  are connected to the control circuit  843  in the touch system circuit  840 ; and an electrode  851  is disposed on the housing. 
     The first output end  8411  of the touch excitation source  841  of the touch system circuit  840  applies a touch signal to each detecting line of the detecting lines  833  simultaneously. The electrode  851  of the housing is connected to the second output end  8412  of the touch excitation source  841  to serve as a return-loop electrode of touch signals. The control circuit  843  of the touch system circuit  840  outputs a turn-on signal to each control electrode line of the control electrodes  832  row by row by scanning, TFTs connected to control electrode lines with the turn-on signals are in an on state, and TFTs connected to control electrode lines without the turn-on signals are in an off state. As the control circuit  843  causes TFTs on each row of control electrode lines to be in the on state, the touch signals on the detecting lines flow into sensing electroding units connected to the row of control electrode lines through the TFTs; and the signal detection circuit  842  of the touch system circuit  840  detects a change of the touch signal on each detecting line simultaneously or column by column. In this way, as the control circuit  843  outputs the turn-on signal to each control electrode line row by row, the signal detection circuit  842  detects a change of touch signals on the sensing electroding units connected to the row of control electrode lines through the TFTs row by row. 
     When a human finger approaches or contacts a sensing electroding unit  831   ji  connected to an electrode line  833   i  in the detecting lines  833  and an electrode line  832   j  in the control electrodes  832 , a coupling capacitance C i  is generated between the finger and the sensing electroding unit  831   ji , a touch excitation signal output by the first output end  8411  of the touch excitation source  841  to the detecting line  833   i  through the touch sampling element  8421  flows into the sensing electroding unit  831   ji  through the TFT of the turn-on signal, flows into the finger through the coupling capacitance C i , flows into the return-loop electrode  851  on the housing of the product through the hand holding the product, and then flows back to the second output end  8412  of the touch excitation source  841  from the return-loop electrode  851 ; and a touch loop is formed by the touch excitation source, the touch detecting line, the sensing electroding unit, the coupling capacitance between the finger and the sensing electroding unit, and the return-loop electrode on the housing. Alternatively, the control electrode lines without the turn-on signals can also be connected to the first output end of touch signals, so as to prevent cross flow of the touch signals in the touch system. 
     A detecting line with a maximum current change or a current change exceeding a threshold can be found by detecting the change of the current in the touch signal flowing through the touch sampling element  8421  simultaneously or one by one; and then according to the control electrode line turning on the active device at this time, the touched sensing electroding unit can be determined, so as to find a position of the finger or other touch object on the touch substrate  810 . Thus, the active touch system  800  becomes a touch system capable of detecting the position of a touch point. 
     The above descriptions are merely preferred embodiments of the present invention, and are not intended to limit the scope of the invention. It is apparent to those of ordinary skill in the art that, modifications and variations can be made without departing from the spirit of the present invention, which should be covered in the protection scope of the present invention.