A method implemented by a computer

Abstract

To determine a new logical area and allocate a pen position, even when a logical area for allocating the pen position is not determined when the pen position is detected.SOLUTION: Provided is a method for outputting a touch position which is a position in a touch surface where a finger contacts, and a pen position which is a position in the touch surface where a pen contacts, by an absolute coordinate expressed by a coordinate system on the touch surface. The method includes: determining whether or not a logical area has already been determined when it is determined that the pen position has been detected; and converting an absolute coordinate indicating the pen position expressed by the coordinate system on the touch surface into an absolute coordinate expressed by the coordinate system of the determined logical area when it is determined that the logical area has already been determined, and on the other hand, determining the logical area on the basis of a window area or the like focused by an operating system and storing the logical area in a memory when it is determined that the logical area has not yet been determined.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a system for a touch pad, and more particularly to a system for a touch pad that enables input operations to a computer using both a finger and a pen. [Background technology]

[0002] There is known an input system that detects the contact positions of a pen and a finger on a display surface in a time-division manner using a group of sensor electrodes arranged in a superimposed manner on a display device, and supplies the detected positions to an operating system. Patent Document 1 discloses an example of such an input system. The positions supplied to the operating system are used for controlling cursor movement and inputting line drawings to a drawing application.

[0003] The data actually supplied from this type of input system to the operating system is usually coordinates expressed in the coordinate system of the display surface. For example, two-dimensional coordinates (x, y) determined by using the long side of the rectangular display surface as the x-axis and the short side as the y-axis are supplied to the operating system as the contact position of the pen or finger. Hereinafter, coordinates expressed in this way in the coordinate system of a certain surface are referred to as "absolute coordinates."

[0004] Some laptop computers and the like have an input system called a touchpad. A touchpad is a device that has a flat surface (hereinafter referred to as a "touch surface") on which a user can slide his or her finger, and is configured to detect the contact position of a finger on this touch surface (hereinafter referred to as a "touch position") and provide the detected position to an operating system. Patent Document 2 discloses an example of such a touchpad.

[0005] The data that a touchpad actually provides to an operating system is usually data indicating the distance and direction of the touch position. For example, the touch position (x N ,y N ) is the end point, and the touch position detected just before it (x O,y O ) is the coordinate that indicates the vector starting from N -x O ,y N -y O ) is supplied to the operating system as data indicating the touch position of the finger. Hereinafter, data indicating the distance and direction of movement of the touch position is referred to as "relative coordinates." Note that if there are no starting coordinates (i.e., immediately after the finger touches the touch surface), no data is supplied to the operating system. Using relative coordinates, the user can move the cursor over the entire relatively large display surface by repeatedly tracing the same area on the relatively small touch surface with his or her finger. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6473554 [Patent Document 2] U.S. Patent No. 9,207,801 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, the inventors of the present application are considering configuring a touchpad so that it is possible to detect not only the touch position but also the contact position of a pen on the touch surface (hereinafter referred to as the "pen position").

[0008] However, the inventors of the present application conducted detailed studies to realize such a touchpad and found that even if a touchpad allows pen input, it is difficult to input line drawings correctly. In other words, when inputting line drawings, positions on the touch surface and positions on the display surface must correspond one-to-one, but such a relationship does not hold in the relative coordinates used for output from the touchpad, making it impossible to input line drawings correctly.

[0009] If the data supplied from the touchpad to the operating system is changed from relative coordinates to the above-mentioned absolute coordinates (in this case, coordinates expressed in the coordinate system of the touch surface), it becomes possible to input line drawings with a pen. However, since the touch surface is generally much smaller than the display surface, even with this configuration, it is difficult to input fine line drawings. In addition, if the data supplied from the touchpad to the operating system is changed to absolute coordinates, the above-mentioned advantages of relative coordinates are lost, which causes problems in controlling the movement of the cursor with a finger.

[0010] Therefore, one object of the present invention is to provide a touch pad system that can suitably realize both cursor control with a finger and line drawing input with a pen. [Means for solving the problem]

[0011] A touchpad system according to the present invention is a system for a touchpad that enables input operations to a computer using both a finger and a pen, the system including a group of sensor electrodes, an integrated circuit, and a device driver executed on the computer, the group of sensor electrodes being arranged superimposed on a touch surface which is an area separate from the display surface of the computer, the integrated circuit being configured to use the group of sensor electrodes to detect a touch position which is a position on the touch surface where the finger is in contact with the touch surface and a pen position which is a position on the touch surface where the pen is in contact with the touch surface, and to supply the detected touch position and pen position to the device driver in absolute coordinates expressed in the coordinate system of the touch surface, the device driver being configured, when supplied with the touch position from the integrated circuit, to convert the touch position into relative coordinates indicating the distance and direction of movement of the touch position and output the relative coordinates, and when supplied with the pen position from the integrated circuit, to convert the pen position into absolute coordinates expressed in the coordinate system of the logical area held at the time the pen position was supplied, and output the absolute coordinates. This is a system for a touchpad. Effect of the Invention

[0012] According to the present invention, the device driver converts coordinates in different ways depending on the type of contact position (touch position or pen position) supplied from the integrated circuit, making it possible to effectively realize both cursor control with a finger and line drawing input with a pen. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a notebook computer 1 according to a first embodiment of the present invention. [Diagram 2] 2 is a diagram showing the internal configuration and functional blocks of the notebook computer 1 shown in FIG. [Diagram 3] 3 is a time-series diagram illustrating the position detection performed by the integrated circuit 31 shown in FIG. 2. [Figure 4] 3 is a flow chart showing details of a process performed by the device driver 20 shown in FIG. 2. [Diagram 5] FIG. 5 is an explanatory diagram of the determination of a logic area performed in step S4 of FIG. [Figure 6] 5(a) is an explanatory diagram of the conversion performed in step S5 of FIG. 4, and (b) is an explanatory diagram of the conversion performed in step S10 of FIG. [Figure 7] FIG. 1A is a diagram showing a method for determining a logical area according to a first variant of the first embodiment of the present invention, and FIG. 1B is a diagram showing a method for determining a logical area according to a second variant of the first embodiment of the present invention. [Figure 8] FIG. 4 shows a touch pad 3 according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0015] Fig. 1 is a diagram showing a notebook computer 1 according to a first embodiment of the present invention. As shown in the figure, the notebook computer 1 is a portable computer, and is configured to include a housing 2, a touchpad 3 having a touch surface T, a right click button 4, a left click button 5, a keyboard 6, and a display 7 having a display surface H. In the example of Fig. 1, the right click button 4 and the left click button 5 are provided separately from the touch surface T, but it is also possible to configure the touch surface T itself as a click button.

[0016] 2 is a diagram showing the internal configuration and functional blocks of the notebook computer 1. As shown in the figure, the notebook computer 1 is configured to have an input / output circuit 11, a CPU 12, and a memory 13 interconnected via a bus 14.

[0017] The CPU 12 is the central processing unit of the notebook computer 1, and is responsible for reading and executing programs stored in the memory 13. The programs thus executed include the operating system of the notebook computer 1, various applications such as a drawing application, device drivers for various hardware, etc. Of these, only the device driver 20 for the touchpad 3 is illustrated in FIG.

[0018] 1 shows a state in which a cursor C and a contract 100 having a signature field 101 are displayed on the display surface H of the display 7. The cursor C is displayed by the CPU 12 executing an operating system, and the contract 100 is displayed by the CPU 12 executing a word processing application.

[0019] 2, the memory 13 is a storage device including a main storage device such as a dynamic random access memory (DRAM) and an auxiliary storage device such as a hard disk. Such memory 13 stores various programs executed by the CPU 12 and various data referenced, generated, and updated by the various programs.

[0020] The input / output circuit 11 is a circuit that functions as an interface for connecting various hardware installed inside and outside the notebook computer 1 to the CPU 12. Specifically, it may be configured with a circuit compatible with the USB (Universal Serial Bus) standard. The hardware connected to the CPU 12 by the input / output circuit 11 includes a touch pad 3, a right click button 4, a left click button 5, a keyboard 6, and a display 7, as shown in FIG. 2.

[0021] The right click button 4 and the left click button 5 are each a push button switch configured so that the user who presses them feels a click, and are used to input a click operation. The keyboard 6 is configured to include various keys including multiple character keys, multiple symbol keys, and multiple function keys. Information that the right click button 4, the left click button 5, and various keys in the keyboard 6 have been pressed is notified to the CPU 12 via the input / output circuit 11.

[0022] The display 7 is a display device configured by, for example, a liquid crystal display or an organic EL display. The display 7 plays a role of displaying characters and images on the display surface H shown in FIG. 1 in response to drawing data supplied from the CPU 12 via the input / output circuit 11.

[0023] The touch pad 3 is configured to include a touch panel 30 and an integrated circuit 31. The touch panel 30 is a capacitive touch panel, and is configured with a touch surface T (see FIG. 1), which is a separate area from the display surface H of the notebook computer 1, and a group of sensor electrodes arranged directly below the touch surface T.

[0024] The touch surface T is formed of a flat surface suitable for a user to slide his / her finger F and pen P shown in Fig. 1 along it. The specific structure of the touch surface T may be a simple flat plate having no particular electrical function, or may be a structure in which the trajectory of the pen P is visualized on the touch surface T, such as a so-called Boogie Board (registered trademark). The latter structure will be described in detail in the second embodiment.

[0025] In one example, the sensor electrode group is composed of a plurality of linear electrodes (hereinafter referred to as "X electrodes") each extending in the short side direction of the rectangular touch surface T, and a plurality of linear electrodes (hereinafter referred to as "Y electrodes") each extending in the long side direction of the rectangular touch surface T. The X electrodes are arranged at equal intervals along the long side direction of the touch surface T, and the Y electrodes are arranged at equal intervals along the short side direction of the touch surface T. However, the configuration of the sensor electrode group is not limited to this, and for example, the sensor electrode group can be composed of a plurality of island-shaped electrodes arranged in a matrix.

[0026] The integrated circuit 31 performs a process of detecting a touch position, which is a position on the touch surface T where the finger F is in contact, and a pen position, which is a position on the touch surface T where the pen P is in contact, using the above-mentioned sensor electrode group. Although a specific method of position detection is not particularly limited, it is preferable to adopt a detection method in which, for example, detection of the touch position by a capacitive method and detection of the pen position by an active electrostatic method are performed in a time-division manner. The touch position and the pen position detected by the integrated circuit 31 are supplied to the device driver 20 via the input / output circuit 11. In this case, the data actually supplied from the integrated circuit 31 to the device driver 20 are absolute coordinates expressed in the coordinate system of the touch surface T.

[0027] 3 is a diagram illustrating, in time series, the position detection executed by the integrated circuit 31. As shown in the figure, the integrated circuit 31 is configured to detect the touch position and the pen position in a time-division manner.

[0028] Figure 3 shows an example in which a user moves cursor C into signature field 101 shown in Figure 1 and gives focus to signature field 101 between time t1 and then writes his or her own name in signature field 101 between time t2 and time t3.

[0029] In this example, the user first slides finger F over touch surface T to move cursor C into signature field 101. Then, the user presses left-click button 5 shown in Fig. 1 to give focus to signature field 101 (up to time t1). During this time, only the touch position is continuously output from integrated circuit 31, and the pen position is not output.

[0030] Thereafter, the user holds the pen P in his / her hand and inputs his / her name on the touch surface T (time t2 to time t3). During this time, only the pen position is continuously output from the integrated circuit 31, and the touch position is not output.

[0031] Returning to FIG. 2, the device driver 20 is a functional unit that constitutes a system for a touchpad together with the sensor electrodes in the touch panel 30 and the integrated circuit 31, and is functionally configured to include a touch position conversion processing unit 21 and a pen position conversion processing unit 22. The touch position conversion processing unit 21 plays a role in converting the coordinates indicating the touch position supplied from the integrated circuit 31 (absolute coordinates expressed in the coordinate system of the touch surface T) into relative coordinates indicating the distance and direction of movement of the touch position, and outputting the relative coordinates. On the other hand, the pen position conversion processing unit 22 plays a role in converting the coordinates indicating the pen position supplied from the integrated circuit 31 (absolute coordinates expressed in the coordinate system of the touch surface T) into absolute coordinates expressed in the coordinate system of a logical area (any area in the display surface H set by a user operation; details will be described later) held at the time of receiving the supply of the pen position, and outputting the absolute coordinates.

[0032] 4 is a flow diagram showing the details of the processing performed by the device driver 20. The processing performed by the device driver 20 will be described in detail below with reference to the diagram.

[0033] 4, the device driver 20 first monitors the occurrence of an interrupt from the touchpad 3 (step S1). When an interrupt from the touchpad 3 occurs, the device driver 20 determines whether the data supplied from the touchpad 3 is a pen position or a touch position (step S2).

[0034] If it is determined in step S2 that the position is the pen position, the device driver 20 determines whether or not the logical area has been determined (step S3). If it is determined that the logical area has not been determined, the device driver 20 determines the logical area based on the window area focused by the operating system (step S4). The logical area determined in step S4 is held in the memory 13 shown in FIG. 2 by the device driver 20.

[0035] 5 is an explanatory diagram of the determination of the logical area performed in step S4. The diagram shows an example in which the operating system displays a window area W1 including a sub-window area W2 on the display 7. The sub-window area W2 is, for example, the signature field 101 shown in FIG.

[0036] If the sub-window area W2 is focused by a user operation, the device driver 20 determines the logical area R so that the entire sub-window area W2 is included. More specifically, the device driver 20 determines, as the logical area R, one of the two logical areas R1 and R2, namely, logical area R1 having a long side the same as the long side of the rectangular sub-window area W2, and having the same aspect ratio and orientation as the touch surface T, and logical area R2 having a short side the same as the short side of the rectangular sub-window area W2, and having the same aspect ratio and orientation as the touch surface T, which will include the entire sub-window area W2 when aligned at the center of the sub-window area W2 (logical area R1 in FIG. 5). However, when the aspect ratios do not need to be equal (i.e., when it does not matter if a line drawing drawn on the touch surface T is stretched vertically or horizontally on the display surface H), the sub-window area W2 itself may be determined as the logical area.

[0037] Returning to Fig. 4, when the logic area is determined in step S4, or when it is determined in step S3 that the logic area has already been determined, the device driver 20 converts the pen position supplied from the integrated circuit 31 into absolute coordinates expressed in the coordinate system of the determined logic area, and outputs the converted value (step S5).

[0038] 6(a) is an explanatory diagram of the conversion performed in step S5. As shown in the figure, when the touch surface T is in the range of x=0 to x M , y=0~y M The logical region R is X=0 to X M , Y=0~Y M If the area is such that: the absolute coordinates (X, Y) output in step S5 are expressed by the following equation (1). (X,Y)=(x×X M / x M ,y×Y M / y M ) ···(1)

[0039] Returning to FIG. 4, the device driver 20, which has output the absolute coordinates in step S5, returns to step S1 and monitors the occurrence of an interrupt from the touch pad 3. Here, while performing this monitoring, the device driver 20 measures the time that has passed since the previous supply of the pen position. Then, if the logic area determined in step S4 is still held in the memory 13 after the predetermined time has elapsed, the logic area is released (steps S6 and S7). In other words, it is deleted from the memory 13. After this, the judgment result in step S3 returns to "not determined."

[0040] Next, when it is determined in step S2 that the touch position is present, if a logic area is held in the memory 13 at that time, the device driver 20 releases the logic area in the same manner as in step S10 (step S8), and then acquires the touch position or pen position supplied immediately before the current touch position (step S9).Then, the touch position supplied this time is converted into relative coordinates indicating the distance and direction from the position acquired in step S7, and output (step S10).

[0041] FIG. 6(b) is an explanatory diagram of the conversion performed in step S10. Point P O is the position obtained in step S7, and point P N is the position provided in step S1. Also, the illustrated vector V is the point P O Starting point is point P N The relative coordinates obtained as a result of the transformation in step S8 are the x-component V of this vector V x and the y-component V y Using (V x ,V y )

[0042] Returning to Fig. 4, after outputting the relative coordinates in step S10, the device driver 20 returns to step S1 and monitors the occurrence of an interrupt from the touchpad 3. After that, the above-mentioned processing is repeated.

[0043] As described above, according to the touchpad system of this embodiment, the device driver 20 converts coordinates in different ways depending on the type of contact position (touch position or pen position) supplied from the integrated circuit 31, making it possible to effectively realize both cursor control with the finger F and line drawing input with the pen P.

[0044] Furthermore, according to the touchpad system of this embodiment, the touch position is output using relative coordinates indicating the distance and direction the touch position has moved, making it possible to achieve cursor control using finger F in the same way as with a conventional touchpad.

[0045] Furthermore, according to the touchpad system of this embodiment, the pen position is output in absolute coordinates expressed in the coordinate system of the logical area held by the device driver 20 at the time the pen position is received, making it possible to suitably input line drawings into any area on the display surface using the pen P.

[0046] Furthermore, according to the touchpad system of this embodiment, when a touch position is detected following a pen position, relative coordinates are detected with the pen position as the starting point, making it possible to move the cursor from the position on the display surface H last specified with the pen P.

[0047] In the above embodiment, an example has been described in which the logical area is determined based on the window area focused by the operating system, but the device driver 20 can also determine the logical area in other ways. Two such examples will be described below.

[0048] FIG. 7(a) is a diagram showing a method of determining a logic area according to a first modified example of the present embodiment. The device driver 20 according to this modified example is configured to determine a logic area based on a window area including a cursor C of the notebook computer 1. In the example of FIG. 7(a), two window areas W1 and W2 are displayed on the display surface H, and the cursor C is included in the window area W1, which is relatively in the background. Therefore, in step S4 of FIG. 4, the device driver 20 determines the logic area R based on the window area W1. This makes it possible to determine the logic area R based on the window area (unfocused window area) in the background as well.

[0049] 7(a), part of the logical area R overlaps with the window area W2, but even in such an area, the device driver 20 can output absolute coordinates indicating the pen position as usual. The operating system or application that receives the absolute coordinates from the device driver 20 can appropriately decide whether or not to enable display of a line drawing in the window area W2.

[0050] Fig. 7(b) is a diagram showing a method of determining a logic area according to a second modified example of the present embodiment. The device driver 20 according to this modified example is configured to determine a logic area based on an area set on the display surface H by a user operation or an application. In the example of Fig. 7(b), an area U (area surrounded by a dashed line) is set by a user operation or an application in a window area W1 displayed by an application, and the device driver 20 according to this modified example is configured to determine a logic area R based on this area U in step S4 of Fig. 4. This makes it possible to determine a logic area R based on any area that is not a window area.

[0051] There is no particular limitation on the specific method of setting the area U. In one example, the user may set the area U by moving the cursor diagonally with the application in a logical area setting mode, or may set the area U by specifying the vertical length, horizontal length, and position with numerical values ​​on the menu screen of the application.

[0052] Next, a touchpad system according to a second embodiment of the present invention will be described. The touchpad system according to this embodiment differs from the touchpad system according to the first embodiment in that the touch surface T is configured with a structure that visualizes the trajectory of the pen P on the touch surface T. Since the other points are the same as those of the touchpad system according to the first embodiment, the same components are given the same reference numerals, and the following description will focus on the differences from the touchpad system according to the first embodiment.

[0053] 8 is a diagram showing a touchpad 3 according to the present embodiment. As shown in the figure, the touchpad 3 according to the present embodiment differs from the touchpad 3 according to the first embodiment in that the touch panel 30 has a pressure-sensitive display 30A and a sensor electrode group 30B, and in that the right click button 4 and the left click button 5, which are also described in the first embodiment, are included as components within the touchpad 3.

[0054] The touch surface T according to the present embodiment is constituted by the display surface of the pressure-sensitive display 30A. The pressure-sensitive display 30A is a display configured so that when the display surface is pressed with a pressure equal to or greater than a predetermined threshold, the color of that portion changes. The pressure threshold that causes the color change is set to a value that is smaller than the pressure applied to the touch surface T by the pen P and larger than the pressure applied to the touch surface T by the finger F. Thus, the pressure-sensitive display 30A is configured to be able to selectively display the trajectory of the pen P on the touch surface T.

[0055] In addition, the pressure-sensitive display 30A is configured to be able to reset the display by applying a predetermined current to a predetermined terminal. The color of the display surface of the reset pressure-sensitive display 30A returns to the color it had before it was pressed with a pressure equal to or greater than a predetermined threshold. This allows the user to use the pen P to write something new on the blank touch surface T.

[0056] The sensor electrode group 30B has the same configuration as the sensor electrode group described in the first embodiment. The right click button 4 and the left click button 5 have the same configuration and role as those described in the first embodiment. However, the right click button 4 and the left click button 5 in this embodiment are connected to the input / output circuit 11 via the integrated circuit 31.

[0057] In addition to having the functions described in the first embodiment, the integrated circuit 31 is configured to supply information indicating that the right click button 4 or the left click button 5 is pressed to the input / output circuit 11 and to cause the predetermined current to flow into the predetermined terminal of the pressure-sensitive display 30A when the right click button 4 or the left click button 5 is pressed. Therefore, the right click button 4 and the left click button 5 according to this embodiment also function as a collective clear button for collectively clearing the display of the pressure-sensitive display 30A.

[0058] As described above, according to this embodiment, the trajectory of the pen P is displayed on the touch surface T. Therefore, input with the pen P can be continued while visually checking the written content on the touch surface T, so that pen input on the touch surface T can be performed more comfortably.

[0059] Furthermore, since the pressure-sensitive display 30A is used, it is possible to display the trajectory of the pen P on the touch surface T with a simpler configuration than when a liquid crystal display or the like is used.

[0060] In this embodiment, an example has been described in which the right click button 4 and the left click button 5 also serve as the all-clear button, but only one of the right click button 4 and the left click button 5 may also serve as the all-clear button, or an all-clear button may be provided separately from the right click button 4 and the left click button 5.

[0061] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be embodied in various forms without departing from the spirit of the present invention.

[0062] For example, in each of the above embodiments, an example has been described in which the present invention is applied to a touchpad of a notebook computer, but the present invention can also be widely applied to touchpads provided in devices other than notebook computers.

[0063] In addition, in each of the above embodiments, the method of coordinate conversion performed by the device driver 20 is changed depending on the type of contact position, but the method of coordinate conversion performed by the device driver 20 may be changed by user settings in any application or operating system. In this way, it becomes possible to input a line drawing with the finger F or control the cursor with the pen P at the user's request.

[0064] In addition, in each of the above embodiments, the device driver 20 executed by the CPU 12 performs the coordinate conversion, but this conversion may be performed within the integrated circuit 31. In this case, it is preferable that the device driver 20 supplies information regarding the logic area to the integrated circuit 31. [Explanation of symbols]

[0065] 1. Laptop 2. Chassis 3. Touchpad 4 Right-click button 5 Left click button 6 Keyboard 7. Display 11 Input / Output Circuit 12 CPU 13. Memory 14 Bus 20 Device Drivers 21 Touch position conversion processing unit 22 Pen position conversion processing section 30 Touch Panel 31 Integrated Circuits 100 Contract 101 Signature C Cursor F finger H Display surface P-Pen R logical area T Touch Surface W1 Window Area W2 Subwindow Area

Claims

1. 1. A computer-implemented method comprising: determining whether a touch position, which is a position on the touch surface that is in contact with a finger, or a pen position, which is a position on the touch surface that is in contact with a pen, has been detected; When it is determined that the touch position has been detected, converting absolute coordinates indicating the touch position expressed in a coordinate system of the touch surface into relative coordinates indicating a distance and a direction of movement of the touch position; When it is determined that the pen position has been detected, it is determined whether or not a logical area has been determined, and when it is determined that the logical area has been determined, absolute coordinates indicating the pen position expressed in the coordinate system of the touch surface are converted into absolute coordinates expressed in the coordinate system of the determined logical area, while when it is determined that the logical area has not been determined, the logical area is determined based on a window area focused on by the operating system, a window area containing the cursor, or an area set by a user operation or an application, and is retained in memory. method.

2. deleting the logic area from the memory when the detection of the pen position has stopped for a predetermined period of time; The method of claim 1.

3. deleting the logic area from the memory when it is determined that the touch position has been detected; The method of claim 2.

4. when it is determined that the touch position is detected following the pen position, the relative coordinates are detected with the pen position as a starting point; 4. The method according to claim 1 .

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