JP4683560B2 - Method for concealing drawing object in electronic blackboard system and electronic blackboard system - Google Patents

Description

  The present invention relates to a concealment processing method and system for automatically identifying a character object to be concealed and concealing it using a concealment object in an electronic blackboard system.

Conventionally, an operation screen of a drawing object generated by a screen generation device composed of a personal computer is input to a display screen projection device, and the operation screen is projected and displayed on a large electronic blackboard by this display screen projection device. An electronic blackboard system that draws drawing objects such as characters and figures on an operation screen is known.
In this electronic blackboard system, it is possible to perform screen processing and various operations using an electronic pen on a projection screen on the electronic blackboard. A drawing object drawn with an electronic pen has a drawing tool written on a screen projected on the electronic blackboard, like a blackboard on a blackboard.

In recent years, class forms that incorporate an electronic blackboard system are attracting attention in schools and other educational settings. By projecting the screen of the personal computer onto the electronic blackboard, many students can share the operation screen of the personal computer operated by the teacher. In addition, the teacher can use the electronic pen and write a drawing object on the electronic blackboard so that the teacher can perform a lesson that is the same as when using the blackboard.
In a lesson using this electronic blackboard system, for example, like a calculation problem, there may be a mix of drawing objects that you want to show on the screen and you want to hide the answer parts that you want to show the calculation formula to students but hide the answer part. sell. As means for hiding the drawing object to be hidden, an application has been devised that moves a rectangular image equivalent to the screen size vertically and horizontally. This application is realized by moving the rectangular image to a position that covers the area to be hidden.

However, in the above application, you can hide a certain area on the top, bottom, left, and right, but if the area you want to hide is mixed on the screen, move the rectangular image to a position that covers all the areas you want to hide, and cover the area you want to show. There is a problem.
Further, as a technique for displaying only necessary data on a screen by concealing unnecessary data, there is one described in Patent Document 1 below.

  Patent Document 1 wants to hide even if the data to be displayed and the data to be hidden are mixed by the concealment setting button for adding the concealment attribute to the data under the cursor and the concealment enable setting button for concealing all the data having the concealment attribute. It is intended to hide only the data. Also, when the data with concealment attribute is hidden and the concealment enable setting button is pressed, if there is data with valid concealment setting, it is changed from valid to invalid, and the data with concealment attribute is displayed again to hide it. I want to show / hide the data I want.

Japanese Patent Laid-Open No. 07-110747

However, in the technique disclosed in Patent Document 1, in order to hide data, it is necessary to manually perform an operation of first selecting data to be hidden and then changing the concealment setting of the data. The amount of operation increases as the amount of data to be hidden increases.
In lessons using the electronic blackboard system, it is desirable that the amount of concealment processing be small so that the lessons can proceed smoothly. The technique of Patent Document 1 has a problem that the amount of operation increases according to the amount of data to be hidden, and there is a problem that it is difficult to use in an electronic blackboard system used for classes and the like.

  An object of the present invention is to provide a drawing object concealment processing method and an electronic blackboard system in an electronic blackboard system that can easily hide a drawing object to be concealed without performing complicated operations.

In order to achieve the above object, the present invention provides a screen generation device that generates an operation screen for drawing a drawing object such as a character, and a projection that displays the generated operation screen on a projection plane of an electronic blackboard. A drawing object such as a character is drawn on the operation screen projected and displayed on the apparatus, and a position coordinate data group having a continuous drawing trajectory is input to the screen generation apparatus and stored in the storage means in the screen generation apparatus as a drawing object. In an electronic blackboard system consisting of an electronic pen to be memorized,
The screen generator is
First means for setting and storing a concealment target attribute designated by the operation of the electronic pen for the drawing object stored in the storage means, and whether each drawing object stored in the storage means is a character object A second object for identifying whether the character object is read from the storage unit among the drawing objects stored in the storage unit, and the concealment target attribute of the character object is set to be valid, A concealed object having a size corresponding to the circumscribed rectangle of the character object is generated, a third means for associating with the character object and stored in the storage means, a drawing object stored in the storage means is read, and the drawing object If it is a character object, the concealment option corresponding to the character object Reads object from said storage means, characterized by comprising a fourth means for concealing the display to display overlaid the concealed object corresponding character object.
Further, the third means includes fifth means for randomly generating a concealment object for a character object for which the concealment target attribute is set to be effective and storing the concealment object in association with the character object. It is characterized by.
Whether or not to perform the random hidden object generation process by the fifth means is specified by an electronic pen indicating a predetermined button displayed on the electronic blackboard.

In addition, a screen generation device that generates an operation screen for drawing a drawing object such as a character, a projection device that projects and displays the generated operation screen on a projection surface of an electronic blackboard, and a projection operation screen An electronic blackboard system comprising an electronic pen that draws a drawing object such as a character and inputs a position coordinate data group having a continuous drawing trajectory to the screen generation device and stores it as a drawing object in storage means in the screen generation device A drawing object concealment processing method in FIG.
The screen generator is
A first step of setting and storing a concealment target attribute designated by operation of the electronic pen for the drawing object stored in the storage unit; and whether each drawing object stored in the storage unit is a character object A second step for identifying whether or not the character object is read from the storage means among the drawing objects stored in the storage means, and the concealment target attribute of the character object is set to be valid, Generating a concealed object having a size corresponding to the circumscribed rectangle of the character object, and storing it in the storage means in association with the character object; and reading out the drawing object stored in the storage means; If it is a character object, A hidden object to be read from the storage means, and the hidden object is displayed on the electronic blackboard by hiding and displaying the hidden object overlaid on the corresponding character object. It is characterized by.

According to the present invention, it is possible to easily hide only an area to be hidden in a screen in which an area to be shown and an area to be hidden are mixed by automatic recognition of character objects and random concealment processing.
In addition, concealment and display can be switched by a simple operation with an electronic pen. Therefore, it can be used smoothly in an environment where questions and answers are displayed on the same screen as in a school lesson using an electronic blackboard system.

Hereinafter, an embodiment for carrying out the present invention will be specifically described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of the entire system according to an embodiment of the present invention.
An electronic blackboard system 1 shown in FIG. 1A projects a control computer 2, a display screen projection device 3 such as a projector connected to the control computer 2, and a projection image from the display screen projection device 3. An electronic blackboard 4, an electronic pen 5 as an input device, and a coordinate reading device 6 that detects input coordinates from the input device are provided.
The operation screen generated by the control computer 2 is projected onto the electronic blackboard 4, and the operator 7 operates the control computer 2 using the electronic pen 5 on the operation screen of the electronic blackboard 5. The observer 8 browses the operation performed by the operator 7 on the electronic blackboard 4.
The electronic pen 5 is provided with a switch 9 as shown in FIG.
The switch 9 is turned on by pressing the tip of the electronic pen 5 against the surface of the electronic blackboard 4. When pressed twice in succession, the control computer 2 identifies as a double click operation.
The coordinate position when the tip of the electronic pen 5 is pressed against the surface position of the electronic blackboard 4 is detected by the coordinate reader 6. The detected coordinate position data is transmitted to the control computer 2 via a connection cable.
The control computer 2 identifies which drawing object has been selected based on the input press coordinate data of the electronic pen 2. Drawing objects such as characters are stored in the storage means of the control computer 2 as a pressed position coordinate data group having a continuous drawing trajectory.

FIG. 2 is a block diagram showing a schematic configuration of the drawing tool according to the embodiment of the present invention.
The drawing tool 200 includes a drawing area 201 that accepts input from the electronic pen 5 and a toolbar 202 that switches functions of the drawing tool 200.
The electronic pen 5 can hide the drawing object 203 by performing an operation in the drawing area 201. Further, by switching functions using the toolbar 202, it is possible to write the drawing object 203 in the drawing area 201 and change the concealment target attribute of the drawing object 203. The written drawing object 203 can be visually hidden by the hidden object 204.
Here, the drawing object is a collection of points input continuously by the electronic pen 5 within a predetermined time. The hidden object is a rectangular object whose area is filled.

FIG. 3 is a block diagram showing a schematic configuration of the drawing object concealment function provided in the control computer 2 of the electronic blackboard system 1 according to the embodiment of the present invention.
As shown in FIG. 3, the drawing object hiding basic function 300 includes a character string drawing object identifying unit 301, a hiding target object size measuring unit 302, a random hiding processing unit 303, a hiding object creating unit 304, and a hiding object. A display unit 305, a concealment target setting unit 306, a drawing object storage unit 307, and a concealment object storage unit 308 are included.
The drawing object hiding function 310 includes a drawing object hiding / display switching unit 311, a random drawing object hiding unit 312, and an electronic pen operation hiding unit 313. Each means of the drawing object hiding function 310 is composed of each means of the drawing object hiding basic function 300. The processing procedure of each means of the drawing object concealment function 310 will be described later.
Each means of the drawing object hiding basic function 300 and the drawing object hiding function 310 is specifically realized by a program stored in the memory of the control computer 2.

The character string drawing object identifying unit 301 identifies a character object among the drawing objects in the drawing area 201 of FIG. 2, and validates the concealment target attribute for the identified character object. Character objects can be identified by using character and graphic recognition techniques for handwritten input data disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-139281, and detailed description thereof will be omitted. A drawing object that is not identified as a character object is a graphic object.
The concealment target object size measuring unit 302 measures a circumscribed rectangle of a drawing object to be concealed. In the measurement method, the horizontal is the difference between the rightmost X coordinate value of the points constituting the drawing object and the leftmost X coordinate value, and the vertical is the difference between the uppermost Y coordinate value and the Y coordinate value of the lowermost point. .
The random concealment processing unit 303 randomly determines whether or not the drawing object to be concealed is to be concealed as it is. The determination process for determining whether or not to conceal is performed by generating a random number and determining whether or not the random number is an even number. If the random number is an even number, the drawing object is set as a concealment target. If the random number is an odd number, it is not set as a concealment target. When it is determined not to be a concealment target, even if the concealment target attribute is valid, no concealment object is created for this drawing object.

The hidden object creating unit 304 creates a hidden object having the same size as the circumscribed rectangle of the target drawing object. The hidden object is set not to be valid / invalid as a hidden object attribute but to have a setting value of “hidden object”.
The hidden object display means 305 displays the hidden object so as to be superimposed on the target drawing object. The hidden object is displayed at a position where the coordinates of the upper left point of the hidden object are the (X coordinate of the leftmost end point, Y coordinate of the uppermost end point) of the target drawing object. By displaying the concealment object at this position, the target drawing object is concealed.
The concealment target setting unit 306 switches the concealment target attribute of the selected drawing object. The concealment target setting has four states: “not set”, “invalid”, “valid”, and “hidden object”. The concealment target setting at the time of drawing object input is “not set”.
The concealment target setting unit 306 switches the concealment target setting from “not set” to “invalid”, “invalid” to “valid”, and “valid” to “invalid”.
When the concealment target setting is “concealment object”, the concealment target setting is not switched.
The drawing object storage unit 307 stores object information of all drawing objects.
The drawing object information includes a drawing object number for uniquely identifying the drawing object, coordinate data of points constituting each object, and a concealment target attribute. When the drawing object is input by the electronic pen 5, the drawing object is stored in the drawing object storage unit 307 provided in the storage device of the control computer 2. At the time of this storage, a concealment target attribute is added and stored. The concealment target attribute includes the character object identified by the character string rendering object identifying unit 301, the rendering object randomly determined by the random concealment processing unit 303, and the rendering object selected by the concealment target setting unit 306. Added.
The hidden object storage unit 308 stores object information of all created hidden objects. The hidden object information includes the drawing object number of the target drawing object.
The drawing object concealment / display switching unit 311 switches between concealment and display for the drawing objects in the drawing area 201 of the drawing tool 200 according to the concealment target setting. When there is a drawing object whose concealment target setting is valid and not concealed, the drawing object is concealed. If all the drawing objects for which the concealment target setting is valid are hidden, all the drawing objects are displayed.
The random drawing object concealment unit 312 uses the random concealment processing unit 303 to randomly conceal the drawing object in the drawing area 201 of the drawing tool 200. However, the character object whose concealment target attribute is invalidated by the concealment target setting means 306 and the graphic object whose concealment target attribute is valid are excluded from random determination because the user explicitly changes the concealment target attribute. It is.
The electronic pen operation concealment unit 313 switches between concealment and display of the drawing object in the drawing area 201 of the drawing tool 200 by a double click operation by the switch 9 of the electronic pen 5. When a drawing object exists at the position where the double-click operation has been performed, concealment and display are switched only for the drawing object. When there is no drawing object at the position where the double-click operation has been performed, the concealment / display switching means 314 is executed.

FIG. 4 is a flowchart showing a processing procedure of the drawing object hiding / display switching means 311 according to the embodiment of the present invention.
The drawing object hiding / display switching unit 311 refers to the drawing object storage function 307 (that is, reads the drawing objects), and acquires the total number of drawing objects (step S401).
Based on the total number of drawing objects, the subsequent processing is sequentially performed on the drawing objects corresponding to the drawing object numbers (step S402).
First, it is determined whether the concealment target attribute of the drawing object n is valid (step S403), and it is determined whether there is a concealment object corresponding to the drawing object n (step S404). Thereby, it is searched whether there is a drawing object in which the hidden object is not displayed even if the hidden object attribute is valid. If there is no drawing object that satisfies this condition, the number of searches n is equal to the total number N of drawing objects (step S405).
When the number of searches n is not equal to the total number N of drawing objects, there is a drawing object that is valid even though the concealment target attribute is valid, and therefore concealment processing is performed on all drawing objects for which the concealment target attribute is valid ( Step S406). The detailed processing procedure of step S406 is shown in FIG.

When the search count n is equal to the total number N of drawing objects, all the drawing objects hidden by the hidden objects are displayed. Again, based on the total number of drawing objects, the subsequent processing is sequentially performed on the drawing objects corresponding to the drawing object numbers (step S407).
When there is a hidden object corresponding to the drawing object n (step S408), the drawing object hidden by hiding the hidden object is displayed (step S409).
By performing the processing from step S408 to step S409 on all the drawing objects, all the drawing objects hidden by the hiding object are displayed.

FIG. 5 is a flowchart showing the drawing object concealment processing procedure in the processing procedure of the drawing object concealment / display switching means 311 according to the embodiment of the present invention.
In the drawing object hiding process in the processing procedure of the drawing object hiding / display switching unit 311 of the drawing object hiding function 310, the total number N of drawing objects stored in the drawing object storage unit 307 is acquired (step S501).
Next, based on the total number N of drawing objects, the subsequent processing is sequentially performed on the drawing objects corresponding to the drawing object numbers (step S502).
First, referring to the drawing object storage function 307, the character string drawing object identification unit 301 identifies whether the drawing object with the drawing object number n is a character object (step S503).
If the drawing object n is identified as a character object, it is determined whether the concealment target attribute is invalid (step S504). In this step, it is determined whether or not the concealment target attribute is explicitly set to be invalid. The character object is not concealed if it is explicitly set to invalid, and concealment processing is performed if it is not set or is valid.

  If the drawing object n is identified as a graphic object, it is determined whether the concealment target attribute is valid (step S505). The graphic object is subjected to concealment processing when it is explicitly enabled by the concealment target setting means 306, and is not concealed when it is not set or disabled.

When performing the concealment process, the concealment object storage unit 308 is referred to (that is, the concealment object is read), and it is determined whether there is a concealment object corresponding to the drawing object n (step S506). If there is a hidden object whose target drawing object is the drawing object n among the hidden objects stored in the hidden object storage unit 308, an unnecessary hidden object is not created because the hidden object has been created.
If the hidden object does not exist, the circumscribed rectangle size of the drawing object n is measured by the hiding object size measuring unit 302 with reference to the drawing object storage unit 307 (step S507).

Next, a hidden object having a circumscribed rectangle size equivalent to the circumscribed rectangle size measured by the hidden object creating unit 304 is created (step S508). The information of the hidden object created at this time is stored in the hidden object storage means 308.
The created concealment object is displayed by the concealment object display unit 305 at a position that is a circumscribed rectangle of the target drawing object (step S509).

  As described above, the processing from step 502 to step 509 is performed on all the drawing objects, thereby identifying the character object and hiding all the drawing objects to be hidden according to the setting of the concealment target attribute in the minimum necessary area. Is possible.

FIG. 6 is a flowchart showing a processing procedure of the random drawing object concealing means 312 according to the embodiment of the present invention.
The random drawing object concealment means 312 is almost the same as the drawing object concealment processing procedure shown in FIG. 5, and the procedure is the same up to step S506. After step S506, it is determined at random whether the concealment processing is performed on the drawing object n by the random concealment processing unit 303 (step 601).
If it is determined not to perform the concealment process, the concealment process is not performed even if the concealment target attribute is valid, and the process proceeds to the next drawing object process.

When it is determined that the concealment process is to be performed, the concealed object creating unit 304 creates a concealed object, and the concealed object display unit 305 displays the concealed object so as to overlap the drawing object (step S602). Step S602 is the same as steps S507 to S509 in FIG.
The random drawing object concealing means 312 can randomly hide the drawing object having the concealment target attribute.

FIG. 7 is a flowchart showing a processing procedure of the electronic pen operation concealment unit 313 according to the embodiment of the present invention.
The display and concealment of the drawing object are switched by a double click operation by the switch 9 of the electronic pen 5.
First, it is determined whether it is a double click operation by the switch 9 of the electronic pen 5 (step S701).
Next, it is determined whether a drawing object exists at the position where the double-click operation has been performed (S 602).
If no drawing object exists, it is determined whether to display or hide all drawing objects in the drawing area 201 according to the concealment target attribute (step S703). This processing procedure is the same as that of the drawing object hiding / display switching means 311 shown in FIG.

  If there is a drawing object at the position where the double-click operation has been performed, it is determined whether the drawing object is a hidden object (step S704). In the case of the hidden object, the drawing object hidden by hiding the hidden object is displayed (step S705). At this time, the target hidden object is deleted from the hidden objects stored in the hidden object storage unit 308.

If the drawing object present at the double-tapped position is not a concealment object, it is first determined whether the concealment target attribute of the drawing object at the position where the double-click operation has been performed is valid (step S706). If the concealment target attribute is not valid (invalid), it is validated (step 707).
Next, a hidden object is created and the hidden object is displayed so as to overlap the drawing object (step 602).
As described above, it is possible to switch between display and concealment for each drawing object or for all drawing objects in the drawing area by a double click operation of the electronic pen 5.

FIG. 8 is a diagram illustrating an example of the drawing tool 200 in the electronic blackboard system 1 according to the embodiment of the present invention.
The drawing tool 200 has a user interface 810 for preparing a teacher before showing it to a student who will be a listener in the class, and a user interface 820 for listening to the student to actually show the student.
The toolbar 811 of the teacher preparation user interface 810 and the student listening user interface 820 includes a random concealment button 812 and a concealment target attribute change button 813.
The random hiding button 812 causes the random drawing object hiding means 312 to be executed after the switch 9 is pressed by the tip of the electronic pen 5. By using the random concealment button 812, it becomes easy to create a problem in which a part of the calculation problem is concealed, such as a worm-eaten problem. In addition, since the drawing objects to be concealed are random, the types of problems can be easily increased.
The concealment target attribute change button 813 causes the concealment target setting unit 306 to be executed for a selected drawing object by selecting the target drawing object with the electronic pen 5 and then pressing it with the tip of the electronic pen 5.

The concealment target attribute change button 813 is pressed when the concealment target attribute of the selected drawing object is valid, and is not depressed when it is invalid. A drawing object for which the concealment target attribute is not set changes the concealment target attribute to invalid when the drawing object is selected. Therefore, even if a drawing object for which the concealment target attribute is not set is selected, the concealment target attribute change button 813 is not pressed.
In the teacher-prepared user interface 810, the circumscribed rectangle of the drawing object whose concealment target attribute is valid is displayed in an identifiable color (dotted rectangle in the figure). As a result, it is possible to identify the entire drawing object whose concealment target attribute is currently set to be effective.
In the student interface 820, the circumscribed rectangle of the drawing object whose concealment target attribute is valid is not displayed in an identifiable color. In the student viewing user interface 820, there is a possibility that the drawing object itself is “to be concealed” itself.

FIG. 9 is an explanatory diagram showing an operation example in the user interface 810 for teacher preparation according to the embodiment of the present invention.
FIG. 9A shows a calculation formula and a figure input by pen input with the electronic pen 5.
FIG. 9B shows a state when a double-click operation is performed with the electronic pen 5 in an area without a drawing object after (a). A drawing object to be concealed is identified and concealed. All drawing objects to be concealed are concealed.
FIG. 9C shows a state when a double-click operation with the electronic pen 5 is performed again in an area where there is no drawing object after (b). Since all the drawing objects to be concealed are concealed, all the concealed drawing objects are displayed.
FIG. 9D shows a state when a double-click operation is performed with the electronic pen 5 at a position where the drawing object is located after (a). Since the drawing object at the position where the double-click operation has been performed is not hidden by the hidden object, a hidden object is generated and hidden.
FIG. 9E shows a state when a double-click operation with the electronic pen 5 is performed again at a position where the drawing object exists after (d). Since the drawing object at the position where the double click operation is performed is hidden by the hidden object, the hidden object is deleted and the hidden drawing object is displayed. Further, since the concealment target attribute is valid for this drawing object, a circumscribed rectangle is displayed in a color for identification.

FIG. 10 is an explanatory diagram showing an operation example of the tool bar 811 of the teacher preparation user interface 810 according to the embodiment of the present invention.
FIG. 10A shows a calculation formula and a figure input by pen input with the electronic pen 5.
FIG. 10B shows a state after the random concealment button 812 is pressed after (a). Randomly conceal the character object to be concealed.
FIG. 10C shows a state after the drawing object 101 is selected and the concealment target attribute change button 813 is pressed after (a). When the selection is made, the concealment target attribute of the drawing object 101 is changed from unset to invalid, and the concealment target attribute becomes valid when the concealment target attribute change button 813 is pressed, and the concealment target attribute change button 813 is pressed.
FIG. 10D shows a state after selecting the same drawing object 101 again after (b). The concealment target attribute of the selected drawing object 101 is changed from valid to invalid. The concealment target attribute change button 813 is not pressed.

As described above, in the present embodiment, a concealment target attribute is added to a drawing object and stored, and the concealment target attribute can be switched between valid and invalid by operating the electronic pen 5, and the concealment target attribute is valid. For the character object that is, it is configured to generate a concealment object that conceals the character object, so that it can be easily concealed without complicated operations, such as in the class It is extremely effective when using.
In addition, an operation for designating a character object to be concealed can be further facilitated by a function of concealing at random.

It is a figure showing a schematic structure of an electronic blackboard system which is one embodiment of the present invention. It is a figure which shows schematic structure of the drawing tool which is one embodiment of this invention. It is a block diagram which shows schematic structure of a drawing object concealment function. It is a flowchart which shows the process sequence of a drawing object concealment / display switching means. It is a flowchart which shows the drawing object concealment processing procedure of a drawing object concealment / display switching means. It is a flowchart which shows the process sequence of a random drawing object concealment means. It is a flowchart which shows the process sequence of an electronic pen operation concealment means. It is a figure which shows an example of the drawing tool which is one embodiment of this invention. It is a figure which shows one operation example of the user interface for teacher preparation. It is a figure which shows one operation example of the tool bar of the user interface for teacher preparation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic blackboard system, 2 ... Control computer, 3 ... Display screen projector, 4 ... Electronic blackboard, 5 ... Electronic pen, 6 ... Coordinate reading device, 7 ... Operator, 8 ... Hearer, 9 ... Switch, 200 DESCRIPTION OF SYMBOLS: Drawing tool, 201 ... Drawing area, 202 ... Toolbar, 203 ... Drawing object, 204 ... Concealment object, 812 ... Random concealment button, 813 ... Concealment object attribute change button

Claims (3)

A screen generation device that generates an operation screen for drawing a drawing object including characters and figures, a projection device that projects and displays the generated operation screen on the projection surface of the electronic blackboard, and a projected operation screen An electronic pen comprising an electronic pen that draws a drawing object including a character and a figure and inputs a position coordinate data group having a continuous drawing trajectory to the screen generation device and stores it as a drawing object in storage means in the screen generation device In the blackboard system,
The screen generator is
First means for setting and storing a concealment target attribute designated by the operation of the electronic pen for the drawing object stored in the storage means;
When the drawing object stored in the storage unit is read and the concealment target attribute of the drawing object is set to be valid, a concealment object having a size corresponding to the circumscribed rectangle of the drawing object is generated, and the drawing object Second means for associating and storing in the storage means;
Reading out the concealed object stored in the storage means, and displaying the concealed object on the corresponding drawing object so as to conceal and display,
The second means randomly determines whether or not a drawing object for which a concealment target attribute is set to be effective is to be a concealment target, generates a concealment object only for the drawing object determined to be a concealment target, and generates The electronic blackboard system according to claim 1, further comprising a fourth means for storing the hidden object in association with the drawing object in the storage means.   2. The method according to claim 1, wherein whether or not to perform the random hidden object generation process by the fourth means is specified by an electronic pen on a predetermined button displayed on the electronic blackboard. Electronic blackboard system. A screen generation device that generates an operation screen for drawing a drawing object including characters and figures, a projection device that projects and displays the generated operation screen on the projection surface of the electronic blackboard, and a projected operation screen An electronic pen comprising an electronic pen that draws a drawing object including a character and a figure and inputs a position coordinate data group having a continuous drawing trajectory to the screen generation device and stores it as a drawing object in storage means in the screen generation device A method for hiding a drawing object in a blackboard system,
The screen generator is
A first step of setting and storing a concealment target attribute designated by an operation of the electronic pen for the drawing object stored in the storage unit;
When each drawing object stored in the storage unit is read and the concealment target attribute of the drawing object is set to be valid, a concealment object having a size corresponding to a circumscribed rectangle of the drawing object is generated, and the drawing object A second step of storing in the storage means in association with
A third step of reading out the concealed object stored in the storage unit from the storage unit and displaying the concealed object on the corresponding drawing object in a concealed manner;
The second step randomly determines whether or not a drawing object for which a concealment target attribute is set to be effective is to be a concealment target, generates a concealment object only for the drawing object determined to be a concealment target, and generates For the hidden object, the fourth step of storing in the storage means in association with the drawing object is executed, and the drawing object displayed on the electronic blackboard is hidden and displayed. Object hiding method.

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