JP5536690B2 - Touch drawing display device and operation method thereof - Google Patents

Description

  The present invention relates to a touch drawing display device including a display device and an input device, and more particularly to a touch drawing display device capable of drawing and operating functions other than drawing for a touch operation and an operation method thereof.

  2. Description of the Related Art In recent years, electronic blackboards having various configurations have been put into practical use as electronic blackboards used in meetings and the like, which is one of touch drawing display devices. In particular, an electronic blackboard device configured as a computer system by combining a display device having a large display screen and an input device for detecting two-dimensional position coordinates such as a touch panel is used.

  In general, the electronic blackboard device sequentially reads position coordinate and movement amount information designated by a pen or the like, and displays an input locus on a display device based on the read information. Thereby, the electronic blackboard device realizes operations as an electronic blackboard such as handwritten input.

  Patent Document 1 below discloses a projection-type presentation apparatus that employs a touch operation and can draw on a displayed screen. In order to solve the problem that it becomes difficult to recognize the original image when it is repeatedly written on the same screen, this device draws while continuously touching in the drawing area, and the touch operation in the drawing area is once finished. Then, when a touch operation is detected next in the drawing area, the previous figure is automatically deleted.

Japanese Patent Laid-Open No. 6-175777

  In the electronic blackboard device as described above, when a specific function other than drawing is assigned to a touch operation different from a simple touch operation for drawing, the specific function should be executed during drawing in the drawing mode. It takes a while to determine that the operation is a touch operation. Usually, in the electronic blackboard device, drawing is performed immediately when touched so as not to cause a time delay (time lag) between the touch operation and the drawing. When there is a time lag, the user feels stressed. For this reason, there is a problem that erroneous drawing unintended by the user is performed. For example, a screen scroll operation may be assigned to an operation of flicking (sliding a touch point so as to play) in a state where multi-touch (simultaneously touching a plurality of points) is performed. In this case, when the user performs a multi-touch flick operation to scroll the screen from a state of drawing with a single touch (single point touch), in order to determine the flick operation, It is necessary to observe the locus of the point touched for a predetermined time. As described above, since drawing is performed promptly in response to a touch so as not to cause the user to feel stress, an erroneous drawing that is not intended by the user is made before it is determined that the operation is a multi-touch flick operation. Will be. Further, when scrolling is performed, an image that has been erroneously drawn disappears from the screen, but the drawing information is stored while including the incorrect drawing. Accordingly, when scrolling back to the original is executed, an erroneous drawing is displayed on the screen again. In the case of printing, an erroneous drawing is printed as well.

  This is a problem that occurs not only in the electronic blackboard device but also in a display device that can display drawing by touch, such as a tablet-type terminal device. This problem is not solved even by the above-mentioned Patent Document 1.

  Accordingly, an object of the present invention is to provide a touch drawing display device and its operation method capable of maintaining correct drawing even when a touch operation other than drawing is performed during the drawing mode.

  The above object can be achieved by the following.

  That is, a touch drawing display device according to the present invention includes a display unit for displaying an image, and a detection unit that is arranged so as to be superimposed on the display unit and detects a touched position. When a line corresponding to the trajectory formed by the movement of the image is drawn on the image displayed on the display unit and an operation other than the drawing is specified by the trajectory, the start point and the end point of the specified trajectory are specified. Erase lines drawn up to now.

  Preferably, the trajectory for specifying an operation other than drawing is a trajectory formed by a multi-touch operation of simultaneously touching the detection unit at a plurality of positions.

  More preferably, a line corresponding to only one of the plurality of tracks formed by the multi-touch operation is drawn.

  An operation method of a touch drawing display device according to the present invention is a touch drawing display including a display unit for displaying an image, and a detection unit arranged to be superimposed on the display unit and detecting a touched position. An operation method of the apparatus, wherein a line corresponding to a locus formed by the movement of the detected position is drawn on an image displayed on the display unit, and the locus is executed during the drawing step. A step of determining whether or not an operation other than drawing is specified; and a step of deleting a line drawn from the start point to the end point of the locus specifying the operation when an operation other than drawing is specified by the locus Including.

  According to the present invention, when a touch operation other than drawing is performed during the drawing mode, a drawing intended by the user can be stored without leaving an erroneous drawing made during determination of a touch operation other than drawing. . Therefore, even when the target image is displayed again, an erroneous drawing is not displayed and the intended drawing can be displayed.

It is a block diagram which shows the outline | summary of a structure of the electronic blackboard apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the detection method of a touch input. It is a figure which shows an example of a display screen. It is a flowchart which shows the control structure of the program which implement | achieves deletion of erroneous drawing in the electronic blackboard apparatus shown in FIG. It is a figure which shows the structure of the coordinate data memorize | stored in the case of multi-touch operation. It is a figure which shows scroll operation by multi-touch operation. It is a figure which shows the scroll of a screen.

  In the following embodiments, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  In the following, “touch” means that the input position detection device is in a state in which the position can be detected. When touching and pressing the detection device, touching without pressing, and contact Including the case of close proximity without. As will be described later, the input position detection device is not limited to the contact type, and a non-contact type device can also be used. In the case of a non-contact type detection device, “touch” means a state in which the input position is close to the detection device up to a detectable distance.

  Referring to FIG. 1, an electronic blackboard device 100 according to an embodiment of the present invention includes an arithmetic processing unit (hereinafter referred to as a CPU) 102, a read-only memory (hereinafter referred to as a ROM) 104, a rewritable memory (hereinafter referred to as a CPU). , RAM) 106, recording unit 108, interface unit (hereinafter referred to as IF unit) 110, touch detection unit 112, display unit 114, display control unit 116, video memory (hereinafter referred to as VRAM) 118, and bus 120. The CPU 102 controls the electronic blackboard device 100 as a whole.

  The ROM 104 is a nonvolatile storage device, and stores programs and data necessary for controlling the operation of the electronic blackboard device 100. The RAM 106 is a volatile storage device. The recording unit 108 is a non-volatile storage device that retains data even when power is cut off, and is, for example, a hard disk drive, a flash memory, or the like. The recording unit 108 may be configured to be detachable. The CPU 102 reads a program from the ROM 104 onto the RAM 106 via the bus 120 and executes the program using a part of the RAM 106 as a work area. CPU102 controls each part which comprises the electronic blackboard apparatus 100 according to the program stored in ROM104.

  Connected to the bus 120 are a CPU 102, a ROM 104, a RAM 106, a recording unit 108, an IF unit 110, a touch detection unit 112, a display control unit 116, and a VRAM 118. Data (including control information) is exchanged between the units via the bus 120.

  The IF unit 110 connects to the outside such as a network, and transmits / receives image data to / from a computer connected to the network. Image data received from the outside via the IF unit 110 is recorded in the recording unit 108.

  The display unit 114 is a display panel (liquid crystal panel or the like) for displaying an image. The display control unit 116 includes a drive unit for driving the display unit 114, reads out image data stored in the VRAM 118 at a predetermined timing, generates a signal for display as an image on the display unit 114, and displays it. Output to the unit 114. The image data to be displayed is read from the recording unit 108 by the CPU 102 and transmitted to the VRAM 118.

  The touch detection unit 112 is a touch panel, for example, and detects a touch operation by the user. Detection of a touch operation when a touch panel is used for the touch detection unit 112 will be described with reference to FIG.

  FIG. 2 shows an infrared cut-off detection type touch panel (touch detection unit 112). The touch panel is arranged in a row so as to face the LED rows 200 and 202, and the light emitting diode rows (hereinafter referred to as LED rows) 200 and 202 arranged in a row on two adjacent sides of the rectangular writing surface. The two photodiode arrays (hereinafter referred to as PD arrays) 210 and 212 are provided. Infrared light is emitted from each LED of the LED rows 200 and 202, and each PD of the PD rows 210 and 212 facing each other detects the infrared light. In FIG. 2, infrared rays are indicated by upward and leftward arrows from the LEDs of the LED rows 200 and 202.

  The touch panel includes, for example, a microcomputer (hereinafter referred to as a microcomputer) (an element including a CPU, a memory, an input / output circuit, etc.), and controls the light emission of each LED. Each PD outputs a voltage corresponding to the intensity of the received light. The output voltage of the PD is amplified by an amplifier. Further, since signals are simultaneously output from a plurality of PDs in each of the PD columns 210 and 212, the output signals are temporarily stored in a buffer and then output as serial signals according to the arrangement order of the PDs and transmitted to the microcomputer. The The order of the serial signals output from the PD column 210 represents the X coordinate. The order of the serial signals output from the PD column 212 represents the Y coordinate.

  When the user touches one point on the touch panel with the touch pen 220, infrared rays are blocked by the pen tip of the touch pen 220. Therefore, the output voltage of the PD that has received the infrared light before being cut off decreases. Since the signal portion from the PD corresponding to the touched position (XY coordinate) is decreased, the microcomputer detects the portion where the signal level of the two received serial signals is lowered and obtains the touched position coordinate. . The microcomputer transmits the determined position coordinates to the CPU 102. Since the process of detecting the touch position is repeated at a predetermined detection cycle, if the same point is touched for a longer time than the detection cycle, the same coordinate data is repeatedly output. Even if the touch detection unit 112 is touched with a finger without using the touch pen 220, the touched position can be similarly detected.

  Since the touched position detection technique described above is well known, further description will not be repeated. The touch detection unit 112 may be a touch panel (capacitance method, surface acoustic wave method, resistance film method, or the like) other than the infrared blocking method. In the capacitance method, the position can be detected without contact as long as the sensor is close to the sensor.

  A screen as shown in FIG. 3 is displayed on the display unit 114. The display screen of the display unit 114 is divided into a drawing area 230 and a function button area 240. The drawing area 230 is an area where the user can draw by a touch operation. That is, the touched point and the XY coordinates of the movement locus thereof are transmitted from the touch detection unit 112 to the CPU 102 as described above. The CPU 102 writes a predetermined value to the corresponding memory address on the VRAM 118 according to the received coordinate data. Although the pixel value of the image data on the VRAM 118 may be changed, here, the VRAM 118 includes an area for storing drawing data (hereinafter also referred to as an overlay area) in addition to the area for storing the image data. And In this case, for example, the data of the memory address in which the overlay area is not drawn is set to “0”, and the CPU 102 writes “1” to the memory address corresponding to the drawing position. The display control unit 116 superimposes the image data and the drawing data (overlay area data) and displays them on the display unit 114. That is, the drawing data is displayed (displays a preset color) at a point where there is drawing data (for example, a pixel in which “1” is recorded in the overlay region), and the point where there is no drawing data (eg, “0” in the overlay region). The image data is displayed in the pixel where “is recorded”.

  In the function button area 240, function buttons 242 to which specific functions are assigned are displayed. A page operation area 250 is displayed below the drawing area 230. In this area, a page feed button 252, a page return button 254, and a page number display field 256 are displayed. When touched, the page feed button 252 is a button for sending the displayed page (image data) to the right side and displaying the next page. When touched, the page return button 254 is a button for sending the displayed page to the left and displaying the previous page. The page number display field 256 displays the number of the currently displayed page among a plurality of pages to be displayed. The page operation area 250 has a fixed position and does not move during scrolling. For example, the data for displaying the page operation area 250 on the display unit 114 may be stored in an overlay area different from the overlay area for drawing.

  When the user touches the page feed button 252, the coordinate data of the touched position is transmitted from the touch detection unit 112 to the CPU 102, and the CPU 102 receives the received coordinate data as the position within the area where the page feed button 252 is displayed. It is determined that Then, the CPU 102 transmits image data of the next page to the VRAM 118 and transmits a page feed command to the display control unit 116. In response to this, the display control unit 116 generates a signal for displaying an image in the middle of page feed from the image data corresponding to the currently displayed page on the VRAM 118 and the image data corresponding to the next page. Generate and output to the display unit 114. As a result, an image in the middle of page turning is displayed on the display unit 114. In the middle of page feed, only the frame of the currently displayed image may be displayed on the display screen of the display unit 114.

  Functions assigned to the function buttons 242 include, for example, a drawing function by touch operation (selectable pen type), a function to open a file (image data) stored in the recording unit 108, and an eraser for deleting drawing in a predetermined area. A function, a function of storing the displayed image data in the recording unit 108, a function of printing the displayed image data, and the like. Each function button 242 is displayed as an icon.

  In the following, an operation method of the electronic blackboard device 100, that is, a control structure of a program that realizes processing for preventing erroneous drawing from remaining when a function other than drawing is assigned to a special touch operation will be described. To do. In the following description, it is assumed that the electronic blackboard apparatus 100 is in a mode in which drawing is performed when a function button for drawing is selected on the screen shown in FIG. 3 and the drawing area 230 of the touch detection unit 112 is touched. To do. A special touch operation is an operation of flicking left and right in a multi-touch state with two or more points. A right scroll is assigned to an operation flicking to the right, and a left scroll is assigned to an operation flicking to the left. Suppose that It is assumed that processing other than drawing is not assigned to other multi-touch operations.

  In step 300, the CPU 102 determines whether or not the touch detection unit 112 has been touched. As described above, the CPU 102 determines whether coordinate data has been received from the touch detection unit 112. From the touch detection unit 112, the position coordinates (X coordinate, Y coordinate) of the touched point are output in the touched order. If it is determined that the touch has been made, the process proceeds to step 302. If it is not determined that the touch has been made, the process proceeds to step 306.

  In step 302, the CPU 102 stores the coordinate data (coordinate data of the touched point) received for a predetermined time in the RAM 106 so that the order of reception can be understood. In step 306, the CPU 102 determines whether or not to end. When the end button assigned to one of the function buttons 242 is pressed, the CPU 102 ends the program. Otherwise, the process returns to step 300 and waits for touch.

  In step 304, the CPU 102 determines whether or not the touch detected in step 302 is multi-touch (a state where a plurality of points are touched simultaneously). Specifically, the CPU 102 calculates the distance between the coordinate data received first among the plurality of coordinate data stored in step 302 and the coordinate data received thereafter. If the distance is greater than or equal to a predetermined value, it is determined that the touch is multi-touch, and if it is less than the predetermined value, it is determined that the touch is single touch.

  Since the touch detection cycle is short, and touching each point has a slight time difference, coordinate data is output from the touch detection unit 112 in the touched order even in multi-touch. Therefore, by calculating the distance between the coordinate data received first and several coordinate data received after the second, it is possible to determine whether the touch is single touch or multi-touch. The number of points touched at the same time by multi-touch is not limited to two points, and may be three or more points, so the distance is calculated for a plurality of consecutive points. The distance used as the reference | standard which determines whether it is multi-touch can be set suitably, and should just be larger than the distance which a user moves a touch point normally during a detection period. If it is determined that it is multi-touch, the process proceeds to step 320, and if it is determined that it is not multi-touch, the process proceeds to step 310.

  In step 310, the CPU 102 draws on the image displayed on the display unit 114 according to the movement locus of the touched point. Specifically, the CPU 102 reads a plurality of coordinate data stored in step 302 from the RAM 106, and assigns the predetermined coordinate points to the points on the overlay area of the VRAM 118 and the points on the line segment that sequentially connect these points. Write the data. Thus, as described above, the image data and the drawing data (overlay area data) are combined and displayed on the display unit 114, and displayed as if they were drawn on the image. Since the process of step 312 is repeated as will be described later, the overlay area is overwritten while leaving the existing drawing data.

  In step 312, the CPU 102 temporarily stores the drawing contents in the RAM 106. Any method may be used as long as the drawing can be reproduced, and the method for storing the drawing is arbitrary. For example, in step 302, the coordinate data stored in the RAM 106 is held as it is while maintaining the order. Further, the overlay area data of the VRAM 118 may be stored in the RAM 106 as two-dimensional image data.

  In step 314, the CPU 102 determines whether or not the touch is maintained. That is, the CPU 102 determines whether coordinate data is continuously received from the touch detection unit 112. For example, when the touch pen 220 or the user's finger is removed, coordinate data is not received from the touch detection unit 112. When it is determined that the touch is maintained, the process returns to step 302, and the processes after step 302 are repeated. If it is not determined that the touch is maintained, the process returns to step 300 to wait for the touch again.

  In step 320, the CPU 102 re-stores the coordinate data stored in the RAM 106 in step 302 on the RAM 106 as coordinate data for each multi-touch position, that is, the trajectory. By the process of step 304, coordinate data of a point touched first (hereinafter also referred to as a start point) is determined for each of the plurality of points touched simultaneously. Therefore, it can be determined by the distance from the start point which of the plurality of start points corresponds to the locus of the start point of each of the plurality of coordinate data other than the start point stored in the RAM 106. Depending on the determination result, the coordinate data of the start point and the coordinate data of the point on the trajectory to which the start point has moved are stored in the order in which they are detected as array data. For example, when two points are touched at the same time, the array data 400 shown on the left side of FIG. Of these, the coordinates of (x0, y0) and (x1, y1) are the two points touched first. The point (x0, y0) was touched slightly earlier than the point (x1, y1). In this case, two data arrays as shown on the right side of FIG. 5 are stored in the RAM 106 with the coordinate data 410 of the first start point and the coordinate data 420 of the second start point as the head. The coordinate data 410 of the starting point and the data array 412 following the start coordinate data 410 represent one locus. The starting point coordinate data 420 and the subsequent data array 422 represent another locus. This is also stored in the case of multi-touch with three or more points.

  In step 322, the CPU 102 draws on the image displayed on the display unit 114 in accordance with the locus of the touched point as in step 310. For example, as shown in FIG. 5, drawing is performed using the coordinate data re-stored on the RAM 106. Note that all the trajectories of the points touched at the same time may be drawn, or only a part of the trajectories (for example, the trajectory of the point touched earliest) may be drawn. FIG. 6 illustrates a case where the user 510 performs a flick operation to the right while performing multi-touch with two fingers after the drawing 500 is performed. By this operation, an incorrect drawing 502 is displayed on the image. In FIG. 6, only the drawing corresponding to one of the two tracks is displayed. If step 312 has already been executed and drawing has been performed by single touch, the drawing content by multi-touch is added to the drawing content.

  In step 324, the CPU 102 temporarily stores the contents drawn in step 322 in the RAM 106. A specific method is the same as in step 312. Note that when the coordinate data re-stored in step 320 is held as it is, only the coordinate data representing the locus drawn in step 322 may be held unlike step 312.

  In step 326, the CPU 102 determines whether or not multi-touch is maintained. That is, the CPU 102 continuously receives a plurality of coordinate data from the touch detection unit 112 and determines whether or not they correspond to a plurality of start point trajectories determined in step 320. For example, when the user releases one finger from the state of touching with two fingers, the trajectory by the released finger is interrupted, and the coordinate data received from the touch detection unit 112 is coordinate data representing one trajectory. Become only. It is determined that multi-touch is maintained if at least two simultaneous touches are maintained including the case where three or more points are touched at the same time. If it is determined that multi-touch is maintained, the process proceeds to step 328. When it is determined that multi-touch is not maintained, the process proceeds to step 314, and it is determined whether single touch is maintained as described above.

  In step 328, the CPU 102 determines whether or not the detected multi-touch operation is an operation assigned to scrolling (operation for designating scrolling). Specifically, for each coordinate data array corresponding to the plurality of touch point trajectories stored in step 320, a vector from the start point coordinate data to the last coordinate data is determined, and the vector is longer than a predetermined length. Whether the X-axis is in the positive direction (X component is positive) or not is determined. If the vector is a vector directed in the positive direction of the X axis, it is determined that the detected multi-touch operation is an operation assigned to scroll to the right. When the vector is longer than a predetermined length and is a vector pointing in the negative direction of the X axis (X component is negative), it is determined that the detected multi-touch operation is an operation assigned to scroll left. If it is determined that the operation is assigned to scrolling, the process proceeds to step 330. If it is not determined that the operation is assigned to scrolling, the process returns to step 320. Until the vector reaches a predetermined length, the processing from step 320 onward is repeated.

  In step 330, the CPU 102 deletes the coordinate data representing the locus of the touch point stored in the RAM 106 in step 324. Specifically, the drawing data written after the multi-touch is determined while holding the drawing data (for example, the single touch drawing data) written before the multi-touch is determined on the overlay area. Delete (for example, write data “0”). Accordingly, an erroneous line drawn by the multi-touch operation is erased on the screen of the display unit 114. FIG. 7 is a diagram showing a display screen of the display unit 114 during scrolling. Arrow 520 represents scrolling in the right direction. In FIG. 7, the erroneous drawing 502 disappears while the drawing 500 created by the user displayed in FIG. 6 is maintained. Since FIG. 7 shows a situation where the scrolling to the right has been performed for a while, a part of the upper right drawing portion is not displayed.

  In step 332, the CPU 102 executes scrolling to the right or left according to the determination result in step 328. Before executing scrolling, the CPU 102 saves the drawing contents temporarily stored in the RAM 106 in steps 312 and 324 (the erroneous drawing has been deleted) in the recording unit 108, and the process returns to step 300. By saving the drawing content of the overlay area in the recording unit 108, when a left scroll is instructed later, an image with the drawing 500 intended by the user can be displayed again.

  As described above, when the left and right flick operations are performed in a state where the user is multi-touched by the user, the electronic blackboard device 100 does not leave an erroneous line drawn by multi-touch before scrolling is started. Scrolling can be performed after saving only the intended drawing.

  In the above, the case where an image read from the recording unit 108 is displayed in the background has been described, but the present invention is not limited to this. The background image may be an image of a uniform color (for example, white, black, gray, etc.) as long as it has a function of drawing by a touch operation on the touch detection unit 112.

  In the above description, the case where the special operation by the touch is the left / right scroll operation has been described, but the present invention is not limited to this. Any operation other than drawing may be used. For example, vertical scrolling, diagonal scrolling, page switching without scroll display, and the like may be used. Also, functions (operations) other than drawing assigned to the function buttons may be used. When detecting an operation assigned to scroll in a direction other than left and right, for example, in step 328 in FIG. 4, the scroll direction is not determined only by the X component of the vector, but is also determined by considering the Y component. That's fine.

  In the electronic blackboard apparatus 100, each of a plurality of users can touch a single touch pen or a finger and simultaneously perform a plurality of drawings. In order to distinguish this operation from the operation assigned to the scroll described above, it is determined whether or not the distance between the simultaneously touched points is about the distance between human fingers (for example, several cm or less). do it.

  In addition, the touch operation is not limited to a multi-touch operation, and may be a single touch operation as long as it can be distinguished from a touch operation for drawing that is normally performed. For example, when the locus from the start point to the end point of the single touch operation (a one-stroke drawing figure) is a predetermined figure, an operation other than the assigned drawing may be executed.

  In the above, the case where the CPU 102 determines whether or not the operation is a multi-touch operation has been described, but the present invention is not limited to this. For example, it may be determined whether the microcomputer of the touch detection unit 112 is a multi-touch operation, and the result may be transmitted to the CPU 102.

  Although the electronic blackboard device has been described above, the present invention is not limited to this, and the present invention can be applied to all display devices that can perform drawing and screen operations by touch, such as tablet-type terminal devices.

  The present invention has been described above by describing the embodiment. However, the above-described embodiment is an exemplification, and the present invention is not limited to the above-described embodiment, and is implemented with various modifications. be able to.

100 electronic blackboard device 102 arithmetic processing unit (CPU)
104 Read-only memory (ROM)
106 Rewritable memory (RAM)
108 Recording unit 110 Interface unit (IF unit)
112 Touch detection unit 114 Display unit 116 Display control unit 118 Video memory (VRAM)
120 Bus 200, 202 LED row 210, 212 PD row 220 Touch pen 230 Drawing area 240 Function button area 242 Function button 250 Page operation area 252 Page forward button 254 Page return button 256 Page number display field

Claims (3)

Display means for displaying an image;
A detection means arranged to overlap the display means and detect a touched position ;
Drawing means for drawing a line corresponding to the locus formed by the detected movement of the position on the image displayed on the display means;
An operation other than drawing is assigned to the specified multi-touch operation,
In response to the user performing the predetermined multi-touch operation, the drawing means erases the line drawn by the predetermined multi-touch operation ,
The predetermined multi-touch operation is a flick operation in a predetermined direction with multi-touch,
An operation other than the drawing is an operation for instructing the display means to scroll the image displayed by the display means . The touch drawing display device according to claim 1 , wherein a line corresponding to only one of the plurality of loci formed by the predetermined multi-touch operation is drawn. An operation method of a touch drawing display device, comprising: a display unit for displaying an image; and a detection unit arranged to overlap the display unit and detect a touched position,
An operation other than drawing is assigned to the specified multi-touch operation,
A drawing step of drawing a line corresponding to the locus formed by the detected movement of the position on the image displayed on the display means;
During the drawing step, determining whether the predetermined multi-touch operation is such a user,
The predetermined multi-touch operation in response to the fact that is determined to have been such, saw including a step of erasing the line drawn by a predetermined multi-touch operation,
The predetermined multi-touch operation is a flick operation in a predetermined direction with multi-touch,
An operation method of a touch drawing display device , wherein the operation other than the drawing is an operation of instructing the display means to scroll an image displayed by the display means .

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