WO2008148307A1 - Method for identifying multiple touch points on an infrared touch screen - Google Patents

Abstract

A method for identifying multiple touch points on an infrared touch screen. The method including: getting a plurality of possible touch points by using grid-shaped scanning firstly, and then eliminating the pseudo-touch point from the possible touch points by using off-axis scanning, finally getting the coordinate of the accurate touch points. The method achieves a goal that detects multiple touch points without changing the structure of the current infrared touch screen.

Description

 Method for identifying multi-touch point of infrared touch screen

 The present invention relates to the field of touch devices, and in particular, to a method for identifying a multi-touch of an infrared touch screen. Background technique

 As a branch of computer touch screen, infrared touch screen is widely used in various fields due to its advantages of convenient installation, maintenance-free, high explosion resistance and high reliability. Although after more than 20 years of development, there are numerous technical improvements, such as those published in Chinese patents or applications with application numbers 95105303.5, 00121462.4. However, the basic technical solutions of the infrared touch screen are still limited to the technical contents disclosed in the patents of U.S. Patent Nos. 3,764,813, 3,775,560, 3,860,754. However, these technical contents are far from the level of technology that infrared touch screens can achieve. All touch detections can only detect a single touch point. With the advancement of computer hardware and software technology, computers have more and more powerful functions, and they are increasingly used in almost any field that we can imagine. Sometimes, for different application fields, sometimes multi-touch technology can better It makes it easier for users to operate the computer, or for specific software, multi-touch technology is more efficient. However, this requires the touch screen to support multi-touch and be able to detect more than one touch point.

At present, for the detection technology of multiple touch points of the infrared touch screen, in the Chinese patent publication CN101071356A, the content of multi-touch point positioning corresponding to two sets of infrared receiving scanning circuits by an infrared emission scanning circuit is disclosed. The patented technology is The multi-touch point positioning is changed by changing the structure of the existing infrared touch screen, which is not compatible with the infrared touch screen in the prior art, and the recognition technology has no practical application prospect; in addition, the patent disclosed in WO2008039006A1 It is disclosed that the content of multi-touch is judged by measuring the maximum acceptable light level when the tube is unblocked by measuring the infrared emission receiving, and the infrared emission in the form of a tube due to the infrared touch screen Receiving the tube, therefore, it is easy to get when measuring the infrared light that is blocked False touch points, the patented technology will produce a large error recognition rate;

JP2007065767, JP2006011568, US2008097991AK US2008088593A1 Patent application and the like disclose several technical solutions for multi-touch recognition, but none of these technical solutions can be applied to an infrared touch screen. Summary of the invention

 In view of the deficiencies of the existing infrared touch screen, the object of the present invention is to provide a method for recognizing a multi-touch on an infrared touch screen, the method being applied to an infrared touch screen, the infrared touch screen comprising: arranging along the periphery of the touch area An infrared transmitting and receiving pair of tube arrays, an auxiliary circuit for turning on the infrared transmitting tube and the receiving tube, and a microcontroller system for controlling the circuit and storing, calculating, and transmitting the detected data, the method comprising the steps of:

 A: Start the infrared touch screen, select each pair of infrared emission and receiving tubes in sequence, and scan the entire touch area;

 B: recording and storing the serial number or address value of the infrared radiation receiving and receiving tube for each infrared ray blocked;

 C: Then judge whether it is single touch or multi-touch, if it is a single touch directly to step E, if it is multi-touch, proceed to the next step D;

 D: selecting an infrared radiation-receiving receiving infrared radiation-receiving pair of transmitting and receiving tubes adjacent to or near the spatial position of the tube but having different axes of the optical axis for off-axis scanning;

 E: according to the recorded and stored infrared emission receiving the serial number or address value of the tube, calculating the coordinate value of the touch point;

 F: Output the coordinate value of the real touch point to the device on which the infrared touch screen is mounted. The off-axis scanning infrared transmitting and receiving tube is selected in the step D as follows: the infrared transmitting and receiving tubes adjacent to the tube are selected with the serial number or address as the center of the infrared transmitting and receiving tube which is blocked by the light.

Before step D, the method further comprises the steps of: combining each of the possible touch points obtained according to the sequenced or address values of the blocked infrared transmitting and receiving tubes recorded in step B. The method for performing the off-axis scanning infrared transmitting and receiving tube in step D may be: selecting at least one straight line that does not intersect with other possible touch points, centering on each possible touch point, and selecting the straight line The transmitting and receiving tubes, which are mounted on the opposite sides of the touch screen and are separated from the light by the infrared radiation, are adjacent to or adjacent to the tube in a spatial position.

 The off-axis scan described in step D includes the following steps:

 S1: centering on the i-th infrared receiving tube corresponding to the blocked i-th infrared transmitting tube, sequentially serializing the serial number or address as im, i-m+1 i- 2, i-1, i, i+ 1. The receiving tube of the serial number or address in the infrared receiving tube of i+2 i+ml and i+m receives the infrared light emitted by the ith infrared transmitting tube; or, instead, sequentially connects the serial number or address to Im, i-m+1, i-2, il, i, i+l, i+2, ......, i+ml, i+m, the serial number or address of the infrared transmitting tube in the infrared transmitting tube, by the first i only the infrared receiving tube receives the infrared ray emitted by the sequentially strobed infrared transmitting tube, wherein m is a set natural number, and i is the serial number or address value of the infrared transmitting receiving tube of the infrared ray blocked in step B;

 S2: detecting step S1 whether infrared rays are blocked during transmission and reception, if no infrared rays are blocked, then returning to step S1; if infrared rays are blocked, proceeding to step S3;

 S3: recording and storing the serial number or address value of the transmitting tube and the receiving tube corresponding to the blocked infrared rays in the vertical direction and the horizontal direction;

 S4: Then return to step S1 until all infrared radiation received by the infrared rays is received to receive the scan of the tube. The natural number m in the step S1 ranges from 10 > m > 2. DRAWINGS

 1 is a schematic diagram of a general principle of multiple touch point recognition of the present invention;

 2 is a flow chart of a main program of multiple touch point recognition of the present invention;

3 is an off-axis scanning mode flow of an embodiment of multiple touch point recognitions of the present invention Cheng Tu

 Figure 4 is a flow chart of the main program of off-axis scanning shown in Figure 3;

 5 is a flow chart of an off-axis scanning method of another embodiment of multiple touch point recognition of the present invention;

 6 is a schematic diagram of the principle of multiple touch point recognitions of the present invention. detailed description

 The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

 Fig. 1 essentially shows the basic mounting structure of the infrared touch screen of the present general structure, and is also the basic mounting structure of the infrared touch screen to which the method of the present invention is applied. As shown, the touch screen is comprised of a rectangular touch screen constructed of an infrared emitter array 102, an infrared receiver tube array 103 mounted around a touch detection area (typically a display area such as a computer display, projector screen) 101. The infrared transmitting and receiving tubes can be the same as the infrared touch screen of the existing structure, and the number is the same, and the infrared transmitting and receiving pair tubes are formed in one-to-one correspondence; the number of the transmitting tubes and the receiving tubes can also be set to be different. However, from the purpose of uniform resolution, it is best to use the same number of tube structures. The following is a description of the implementation of the method of the present invention based on the "on-tube" structure.

It is assumed that there are two touches (solid circles in the figure) 107 and 109 in the scanning detection area of the touch screen of this structure, which are represented by characters B and D, respectively, when the infrared transmitting and receiving tube scans the touch area, There will be at least two pairs of tubes in the lateral and longitudinal directions, respectively (depending on the size of the touch object, more likely there will be more pairs of tubes, here the two principles are assumed to be explained) the infrared light will be blocked. Thus, in the flow of the scanning of the transmitting and receiving tube array as shown in FIG. 2: It is assumed that in the longitudinal direction, the two pairs of tubes whose light is blocked are numbered a and b; in the lateral direction, the number of rays blocked by the two pairs of tubes is ( : and <1. This is equivalent to the internal coordinate system XOY in which the serial number of the transmitting and receiving pairs, or the scanning receiving address of the transmitting and receiving tube in the microcontroller is measured in the coordinate direction, which will appear in the vertical direction and 13 The coordinate values of the two touch objects, the coordinate values of the two touch objects of c and d will appear in the horizontal direction. By combining these four coordinate values, A(c, a), B(c, b), C can be obtained. (d,b) and D(d,a) four touches possible Location, ie four possible touch points. However, the microcontroller inside the touch screen cannot immediately determine which of the four touch points is a pseudo touch point generated by the coordinate combination, and which is the actual touch point, so other methods are needed to remove the pseudo touch point. The actual touch point. In Fig. 1, the pseudo touch points are respectively A. point 106 and point C 108 indicated by a dotted circle. In the figure, the infrared rays emitted from the launch tube are indicated by an arrow line 104, and the infrared rays blocked by the touch object are indicated by an arrow dotted line 105.

 At this point, the core scanning method of the present invention - off-axis scanning - can be initiated. When the method is used to scan and detect the horizontal and vertical directions of the touch screen, the touch object not only blocks at least two pairs of transmitting and receiving infrared rays between the tubes in the longitudinal and lateral directions, but also has an infrared ray of "off-axis" between the tubes. Block. The so-called off-axis scanning is to receive infrared rays from a pair of infrared emission receiving tubes in the tube, and another pair of transmitting and receiving tubes in the receiving tube to receive infrared rays. Since the optical axes of the two pairs of tubes are separated, not the same optical axis, they are defined as off-axis scanning in the present invention. As shown in FIG. 5, the infrared transmitting tubes in the touch screen are generally infrared light emitting diodes, and the infrared rays emitted by the light emitting diodes are not concentrated, but distributed in a conical region centered on the optical axis. Therefore, the receiving tube which deviates from the optical axis of the transmitting tube within a certain range can also receive a sufficient photoelectric signal sufficient to be detected, so off-axis detection (or scanning) is possible. Of course, in this case, there is a certain requirement for the distance and angle between the launch tube and the receiving tube, and the maximum allowable deviation position needs to be determined according to factors such as the product manual, the size of the touch screen, or an experiment. However, for a general-sized touch object and a touch screen, it is generally possible to detect an off-axis photoelectric signal in the case of several tube positions (pipe mounting positions).

Figure 2 shows the flow chart of the entire test, corresponding to the main steps above. Step 201 is a startup step of detecting, entering a detection procedure, and then entering a scanning step 202; determining, by the detection determining step 203, whether or not infrared rays are blocked between the tubes, and if no infrared rays are blocked, returning after completing one scanning cycle Scanning control section, continue to control each transmitting and receiving tube to scan the entire touch area, when an object is detected blocking red When the external line is recorded, the serial number or address value of the infrared radiation receiving tube pair that is blocked by each infrared ray is recorded and stored; then, the determining step 204 is performed, and it is judged that the infrared rays between the pair of tubes in the longitudinal direction and the lateral direction are blocked, if at some In the direction, only the infrared rays between the pair of tubes are blocked, and then it is determined as a single touch; the calculation conversion step 205 is entered, and the internal coordinate calculation of the touch point is converted into the coordinate value of the specified format according to the requirements of the computer system on which the touch screen is installed. Outputting to the computer system through the connection port, and then returning to step 202; if there is a light between more than one pair of tubes blocked in a certain direction, it is considered to be a multi-touch, and then proceeds to step 206, according to the storage of infrared rays The blocked address or serial number of the pair of tubes gives a number of possible coordinate values of the touched point, such as points A, B, C, and D in FIG. Then, proceeding to step 207, the off-axis scanning function is activated. After the result of the off-axis scan is obtained, the determination calculation step 208 is entered to determine which of the internal coordinates of the touch points obtained by the combination are true touch points, and the pseudo touch points are removed. Finally, the coordinate value of the real touch point is processed in the processing manner as described in step 205, and output to the computer system through the connection port. After completing these steps, return to the scan control step 202 to start the next scan detection. In the first embodiment, since the off-axis scanning is started based on the serial number or address i of the transmitting and receiving pair tube blocked by the infrared rays, after the step 204 is judged that the plurality of pairs of tubes are blocked, the steps may be skipped. 206, directly start off-axis scanning, eliminating the step of calculating a plurality of coordinate values. However, in Embodiment 2, since the manner of off-axis scanning is centered on each possible touch point obtained by the combination, the above corresponding steps are necessary.

 Because the working principle of the infrared touch screen is open technology, the above-mentioned technical contents such as detection, judgment, calculation, etc. are all contents of programming and mathematical calculation, so there is no need to elaborate here.

Example 1·.

In an embodiment of the invention, there may be two ways to select off-axis scanning of the transmitting and receiving tubes adjacent or adjacent to the spatial position of the tube by infrared radiation receiving that is blocked by the light. The first type is as shown in the flowchart of FIG. 3, and the infrared light that is separated by the light is selected. The transmitting and receiving tubes that are centered on the tube and whose serial number or address is adjacent to but with different axes of the optical axis are scanned off-axis. Taking the touch point D(a, d) obtained by the combination in Fig. 1 as an example: Assume that in the vertical direction, the serial number or address of the tube blocked by the infrared point D is i, where i=d, then the serial number can be selected separately. Or the transmitting tubes with the addresses il, i, and i+1 emit infrared rays. When each of the above transmitting tubes emits infrared rays, the serial numbers or addresses may be selected as i-2, il, i, i+l, i+2, respectively. Receive tube reception. As can be seen from Fig. 1, since the touch point D is real, the infrared rays from il → i + l, i + l → il are completely blocked; il → i, i + l → i, and i → il The infrared rays of i→i+l are partially blocked. At this point, it can be judged that point D is a real touch point. And point C, because the infrared rays between i→il, i→i+l and il→i+2, i+l→i-2 that should be blocked by point C are not blocked, it means that point C is a Pseudo touch point. This is only detected by the longitudinally arranged transmit and receive pairs, and can also be detected again by using the horizontally arranged transmit and receive pairs to further confirm which is true and which is the pseudo touch point. Other possible touch points A, B, and C are also used to determine the truth. In fact, the geometric basis of this detection method is the solution to the intersection of the linear equations. Since the position of all the transmitting and receiving tubes is known and fixed in the coordinate system XOY over the entire touch screen, the equation for the straight line (infrared) between any one of the transmitting tubes and any one of the receiving tubes is It is known that the coordinate values of all the intersections between these straight lines are well known, and according to the geometric principle, there is an intersection between the lines that are not parallel on the plane. If two or more of these lines are cut together (infrared is blocked), then the blocking point must be the intersection of the two or more lines. If the touch screen has only one direction (for example, the longitudinal direction shown in the figure), the above method can already detect the precise position of the touch point in the Y direction and the approximate position in the X direction; however, the touch screen has another direction. The scanning detection (horizontal shown in the figure) can obtain the approximate position of the touched point in the X direction and the approximate position of the Y direction as described above. In this way, the infrared touch screen can accurately obtain the position of each touch point, not just one touch point. Corresponding to Fig. 3, step 207 in Fig. 2 is replaced by a more specific step 301, which replaces step 208 in Fig. 2, and then returns to scan step 202 in Fig. 2.

 In order to more clearly illustrate the first off-axis scanning implementation method of the present invention, it is first assumed that the maximum number of the transmitting and receiving tubes is N (here only the scanning order of the transmitting or receiving tubes is described by the sequence number from small to large, The transmitting and receiving tube addresses can also be converted into serial numbers; and from the structure of the infrared touch screen, other arrangement rules can also be converted into small to large serial numbers). The working process of the infrared touch screen using the off-axis scanning method of the present embodiment is as follows: The micro-controller sequentially illuminates the infrared transmitting tube in order of small to large numbers to emit infrared rays. After each of the transmitting tubes of the serial number i is selected, the infrared receiving tube on the opposite side of the transmitting tube is centered on the receiving tube paired with the gated transmitting tube, and the microcontroller sequentially strobes continuously The plurality of adjacent coaxial and off-axis receiving tubes adjacent to the receiving tube receive the infrared rays emitted by the transmitting tube. It is assumed that, except for the receiving tube paired with the transmitting tube, the number of the receiving tubes that are sequentially gated is 2 m, and the serial number j of the receiving tubes sequentially gated by the microcontroller is respectively ·. j = im, I-m+1

I-2, il, i, i+l, i+2 i+ml, i+m. Here m is the set natural number, which can be based on the size of the touch screen and the required response time: m value is large, precision is high, scan period is long, response speed is slow, otherwise m is small, scan period is short, response fast. Therefore, generally take m = 2 ~ 10, that is, 10 ≥ m ≥ 2. When the receiving tube paired with the transmitting tube i is located at the edge of the touch area, some of the serial numbers may not exist: for example, when i = 1, it is already the edge of the transmitting or receiving tube, im, i- m+1 i-2, ί-1 These receiving tubes do not actually exist; when i = N, i+l, i+2 i+ml, i+m do not exist, in this case Since it is not necessary to consider any touch points other than the edge of the screen, it is still possible to judge the true one by using half of the number of transmitting and receiving tubes on the i side and according to the aforementioned method and the geometric and mathematical relationship between the transmitting and receiving tubes. Touch the point. In the middle of the scanning process, the terminating tube in one direction and the starting tube in the other direction are also the above cases. During the entire scan detection process, all infrared transmitting and receiving tubes are gated according to the above rules, until i=N, one frame of the touch area is completed. Scan.

 The above-described principle of off-axis scanning mode detection of the present invention will be described in detail below with reference to FIG. Figure 4 shows the flow chart of the program for off-axis scanning. The program flow shown does not completely correspond to the main program of Figure 2, here is only to explain the detection principle of the above-mentioned off-axis scanning, if embedded in Figure 2 In the main program shown, the main program shown in FIG. 2 is directly transferred to step 402, and after completing the off-axis scanning of all the infrared-infrared-emitting infrared radiation receiving tubes, returning to the main program shown in FIG. The modifications and variations made in the main program shown in FIG. 2 to the program shown in FIG. 4 will be understood and implemented by those skilled in the art. Step 401 is a startup step of detecting, entering a detection procedure, and then entering a scanning step 402, selecting an infrared transmitting tube of serial number i in order. Then, proceeding to step 403, sequentially selecting the receiving tube of sequence number j to receive the infrared rays emitted by the transmitting tube according to the serial number i and the set m, completing a receiving small loop for the transmitting tube i, and determining whether by step 404 Light is blocked. If there is infrared light blocked, record the values of i and j. If no infrared rays are blocked, then return to control step 402 to continue selecting the next launch tube i to resume the next round of scan detection. This cycle completes one frame detection. If it is judged that light is blocked, a recording step 405 is performed to record the number of the blocked transmitting tube and the serial number of the receiving tube, i.e., the value of j.

 After the program is executed here, the following steps can be set according to the calculation speed of the microcontroller, the scanning cycle of the touch screen, etc. There are two ways to choose.

The first is a centralized processing method, that is, between two frames of scanning, based on the values of the respective i, j recorded in the memory, a straight line equation is constructed in the manner described above to solve the coordinate values. In FIG. 4, the execution path of this mode is after step 405, and proceeds to decision step 408 to determine whether a set of j values of at least one point in two directions is obtained. If not, then return to step 402 to continue the scan detection; if so, then by step 409, it is further determined whether a frame scan has been completed. If the result of the determination is that one frame scan has been completed, then the calculation step 410 is entered, and the coordinate values of the real touch points are obtained by the method described above, and then return to step 402 to start the scan detection of the next frame. Calculated The coordinate value of the touched point is transferred to the computer system using the touch screen through the data transmission step 411 within the set time. In this way, the advantage is that the computing power of the microcontroller is not high, the processing process is clear and centralized, and the writing is relatively simple; the disadvantage is that the real-time response capability is slightly poor; the quick response is prone to slow response.

 The second is a decentralized approach where some or all of the data is processed during the scan. Another branch after step 405 is shown in Figure 2. After recording the values of a set of i, j, for example, the i, j values are obtained in the lateral direction of the touch screen, and by step 406, a straight line equation for the transmitting and receiving tubes blocked by the light is established, as described above. The intersection point where the straight line intersects is the condition of knowing, and the precise position of the touched point in the X direction and the approximate position in the Y direction are obtained, and then by judging step 407, it is judged whether or not another direction is obtained in the other direction (longitudinal direction). A set of i, j values. If the i, j value is not obtained in another direction, it indicates that the other direction has not been scanned yet, and should return to step 402 to continue the scan detection; if the j direction of the other direction is obtained, proceed directly to step 410. Using the method described above, the coordinate value of the real touch point is solved, and then the process returns to step 402 to continue the cycle of the scan detection. In this way, the advantage is that the real-time response capability is very good, especially for quick operation, and has better use effect. The disadvantage is that the computing power of the microcontroller is relatively high, and the programming of the program is complicated.

 Although two different program flows for detecting and calculating touch points are given above, they can also be mixed in two ways. For example, in the second mode, first, according to i, j, the corresponding light is blocked. Straight line, then wait until the completion of a frame scan, in detail the coordinates of the touch point. From the above description of the specific embodiments with reference to the accompanying drawings, it is understood that there are many combinations of steps.

In addition, the above scanning process can also be implemented by cyclically turning on the transmitting tube and fixing the receiving tube. A brief description is as follows: Sequence serial number or address is im, i-m+1, i-2, il, i, i+l, i+2 i+ml, i+m The transmitting tube in which the serial number or address is actually present in the tube, the infrared radiation emitted by the above-mentioned sequentially strobed infrared transmitting tube is received by the i-th infrared receiving tube, and it is determined which one is the real touch point by detecting which infrared rays are blocked. It is a pseudo touch point. This method is identical to the principle and detection effect of using the plurality of receiving tubes centered on i to receive the infrared rays of the transmitting tube of the serial number or address i as described above, and thus will not be repeated.

Example 2

 Another way of selecting off-axis scanning of the transmitting and receiving tubes adjacent or adjacent to the spatial position of the tube by infrared radiation reception that is blocked by the light is as illustrated in Figure 5: Centering on each possible touch point, making at least one straight line, selecting the emission of the opposite side of the touch screen, which is installed on the opposite sides of the touch screen, adjacent to or near the spatial position of the infrared emission receiving tube that is blocked by the light. Tube and receiver tube. Of course, as previously mentioned, to ensure sufficient intensity of off-axis light, the smaller the angle between the line and the optical axis of the tube to which the light is blocked, the better. Still taking the point D in Fig. 1 as an example, the transmitting tube i-1 and the receiving tube i+1 through which the straight line 110 is connected can be selected to verify whether the point D is a real touch point or a pseudo touch point. Compared with the first method above, this method can confirm the authenticity by simply selecting a pair of suitable transmitting and receiving tubes to scan once. This method requires the equation of this line to be calculated in advance, so the processing time is slightly longer. But now the speed of the microprocessor is very fast, and it is a linear equation, so it should be faster than the scanning method of the first method, which can reduce the scanning period of the whole area and improve the response speed of the touch screen. Of course, you can also use the look-up table method to store each possible line equation in the memory and call it directly when needed. At this time, the system needs to have a relatively large memory. Corresponding to Fig. 5, step 501 is substituted for 301 in Fig. 3. However, it should be noted that this line cannot intersect with the coordinate points obtained by other combinations, otherwise it is impossible to determine which point blocks the light.

 The off-axis scanning main program of this embodiment can be converted from Embodiment 1, and will not be described in detail herein.

The above embodiment gives the case of two touch points, but in the case of more than two touch points, the same method in the embodiment can still be used to detect the processing, including some The connection between the touch points may be parallel to the horizontal or vertical infrared rays (this is easier to handle), so no further explanation is needed.

 The basic technical solutions for achieving the object of the present invention have been highlighted above. However, as a complete application technology solution, the implementation structure explicitly stated above is not unique. For example, the step of calculating the coordinate value of the receiving format of the computer connected to the touch screen may be set to remove the coordinate value corresponding to the point after confirming that the point is a pseudo touch point before the pseudo touch point is removed. For example, in the first off-axis scanning scheme, it is also possible to first connect a selected receiving tube, and then sequentially connect the selected transmitting tubes; after all the selected transmitting tubes have emitted infrared rays, This is achieved by connecting the second selected receiving tube and then sequentially connecting the selected transmitting tubes one by one, reducing the transient process and ensuring that the received photoelectric signal is more stable. Therefore, the design of the improvement, the transplantation, the modification, the deletion, the addition, and the like based on the basic technical solutions given by the present invention are all within the technical scope of the present invention. Industrial applicability

 Through the above description of the invention, it can be seen that the advantages of the present invention are that, without changing the structure of any existing infrared touch screen, the detection can be realized only by changing the execution code in the microcontroller that controls the operation of the touch screen. The purpose of touching points. Therefore, the present invention has the advantages of extremely low application cost and wide applicability; especially for some special applications, the detection of multiple touch points can be realized very easily.

Claims

Claim  What is claimed is: 1. A method of identifying a plurality of touch points on an infrared touch screen, the method being applied to an infrared touch screen, the infrared touch screen being arranged by an infrared transmitting and receiving pair of tubes arranged around the touch area, turning on the infrared transmitting tube and The auxiliary circuit of the receiving tube and the microcontroller system for controlling the circuit and storing, calculating, and transmitting the detected data include the following steps:  A: Start the infrared touch screen, select each pair of infrared emission and receiving tubes in sequence, and scan the entire touch area;  B: recording and storing the serial number or address value of the infrared radiation receiving and receiving tube for each infrared ray blocked;  C: Then judge whether it is single touch or multi-touch, if it is a single touch directly to step E, if it is multi-touch, proceed to the next step D;  D: selecting an infrared radiation-receiving receiving infrared radiation-receiving pair of transmitting and receiving tubes adjacent to or near the spatial position of the tube but having different axes of the optical axis for off-axis scanning;  E: according to the recorded and stored infrared emission receiving the serial number or address value of the tube, calculating the coordinate value of the real existing touch point;  F: Output the coordinate value of the real touch point to the device on which the infrared touch screen is mounted.  2. The method according to claim 1, wherein the method for selecting the off-axis scanning infrared transmitting and receiving tube according to step D is: centering on the infrared transmitting receiving tube that is blocked by the light , select the serial number or address adjacent to the infrared transmitting and receiving tubes.  3. The method according to claim 2, wherein the off-axis scanning in step D comprises the following steps: S1: centering on the i-th infrared receiving tube corresponding to the blocked i-th infrared transmitting tube, sequentially serializing the serial number or address as im, i-m+1, ..., i-2, i-1, i, i+1, i+2 i+ml, i+m, the receiving tube of the serial number or address in the infrared receiving tube, receiving the infrared rays emitted by the ith infrared transmitting tube, or sequentially serializing the serial number or The address is im, The i-m+l, i-2, il, i, i+l, i+2, ......, i+ml, i+m infrared transmitting tubes have serial numbers or addresses in the actual transmitting tube, from the i The infrared receiving tube receives the infrared ray emitted by the sequentially strobed infrared transmitting tube, wherein m is a set natural number, i is a serial number or an address value of the infrared transmitting receiving tube of the infrared ray blocked in step B; S2: detecting Is there any infrared rays blocked during the transmission and reception of step S1, if no infrared rays are blocked, then return to step S1; if there is infrared light blocked, proceed to step S3;  S3: recording and storing the serial number or address value of the transmitting tube and the receiving tube corresponding to the blocked infrared rays in the vertical direction and the horizontal direction;  S4: Then return to step S1 until all infrared radiation received by the infrared rays is received to receive the scan of the tube.  4. The method according to claim 1, wherein before step D, the method further comprises the steps of: combining the blocked infrared transmission and the serial number or address value of the receiving tube recorded in step B; Touch point.  The method according to claim 4, wherein the method for selecting the off-axis scanning infrared transmitting and receiving tube in step D is as follows: at least one of the possible touch points is centered Other possible straight lines where the touch points intersect, 'select the transmitting and receiving tubes that are connected to the opposite sides of the touch screen and are separated from the two sides of the touch screen by infrared radiation receiving the light adjacent to or adjacent to the tube in the spatial position. .  6. The method according to claim 5, wherein the natural number m in the step S1 ranges from 10 > m > 2.