Abstract:
A portable graphic computer apparatus is comprised of a tablet for inputting coordinates data, a detecting circuit for detecting the coordinates data inputted by the tablet, a video image data forming circuit for forming video image data corresponding to input coordinates based on coordinates data by an output signal from the detecting circuit, a memory for storing the video image data, a video signal generating circuit for generating a video signal from the video image data, an output circuit connected to the video signal generating circuit for outputting the video signal, a cabinet for accommodating therein the above elements, and a plurality of color selecting buttons formed on the tablet for selecting color informations of the video image data, wherein the video image forming circuit identifies the designation of the color selecting buttons and for forming the video image data on the basis of the designated color.

Description:
This is a continuation of application Ser. No. 07/560,783 filed Jul. 31, 1990 is now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to image forming apparatus and, more particularly, is directed to a portable graphic computer apparatus suitably used by children to draw a picture. 
     2. Description of the Prior Art 
     When drawing a picture, children used to draw a picture on a drawing paper with crayons and colored pencils, in which case a mistake on the picture could not be corrected with ease. Also, the children could not express their ideas freely by drawing pictures because the number of drawing papers is restricted. 
     Therefore, an image forming apparatus has been proposed, in which a tablet having, for example, a coordinates detecting apparatus, a personal computer having a software for processing inputted coordinates and a television monitor for displaying a video signal generated from the personal computer are combined to display a locus drawn on the tablet on a picture screen of the television monitor. In this case, the picture displayed on the monitor can be corrected with great ease, and the user can draw pictures freely over and over. 
     An electronic picture drawing apparatus is disclosed, for example, in U.S. Pat. No. 4,764,763. In this picture drawing apparatus, coordinates are inputted by moving a cursor on a display panel by turning right and left knobs. Accordingly, the fundamental idea of this apparatus is different from that of the present invention. 
     However, since the tablet having the coordinates detecting apparatus and the personal computer having the predetermined software are independently provided as described above, the overall arrangement of the apparatus becomes large in size and the interconnection thereof becomes complicated. There is then the disadvantage that children cannot use this apparatus with ease. 
     Furthermore, in order to realize the above-mentioned portable graphic computer apparatus in actual practice, colors of, for example, a picture displayed on the picture screen of the television monitor must be changed in a version of, for example, 10 different colors, and various functions such as an eraser function and the like must be provided additionally. This needs many more operation buttons for designating colors and functions. If mechanical switch buttons are increased in this way, the mechanical portion thereof becomes complicated in arrangement and the manufacturing cost is increased. 
     Moreover since electronic, relatively expensive image forming apparatus is utilized, it is desirable that other more sophisticated functions than the drawing are also provided. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide an improved portable graphic computer apparatus which can eliminate the aforenoted shortcomings and disadvantages encountered with the prior art. 
     More specifically, it is an object of the present invention to provide a portable graphic computer apparatus in which an overall arrangement is accommodated within a cabinet and is simplified so that this graphic computer can be suitably used by children. 
     Another object of the present invention is to provide a portable graphic computer apparatus in which the mechanical portion can be simplified in arrangement and other functions can be extended additionally. 
     Still another object of the present invention is to provide a portable graphic computer apparatus in which, if a display device is mounted on a cabinet as an output device, the overall arrangement can be more simplified, and a coordinate portion and a video image display portion are provided close to each other, thus making this graphic computer apparatus more useful. 
     A further object of the present invention is to provide a portable graphic computer apparatus in which an alarm sound is emanated so that the user can be prevented from leaving a power switch in its ON state inadvertently. 
     Still a further object of the present invention is to provide a portable graphic computer apparatus in which demonstration video data is formed after a predetermined period of time so that this graphic computer apparatus is suitably exhibited at shop front for demonstration. 
     Still a further object of the present invention is to provide a portable graphic computer apparatus in which a tracing sheet can be provided on a tablet with ease. 
     Yet a further object of the present invention is to provide a portable graphic computer apparatus in which a tracing sheet mounted on a tablet is used by the children to do a kind of learning so that this graphic computer apparatus becomes more convenient. 
     As a first aspect of the present invention, a portable graphic computer apparatus is comprised of a tablet for inputting coordinates data, a detecting device for detecting the coordinates data inputted by the tablet, a video image data forming device for forming video image data corresponding to input coordinates based on coordinates data by an output signal from the detecting device, a memory for storing the video image data, a video signal generating device for generating a video signal from the video image data, an output device connected to the video signal generating device for outputting the video signal, a cabinet for accommodating therein elements from the tablet to the video signal generating device, and a plurality of color selecting buttons formed on the tablet for selecting color informations of the video image data, wherein the video image forming device identifies the designation of the color selecting buttons and forms the video image data on the basis of the designated color. 
     As a second aspect of the present invention, a portable graphic computer apparatus is comprised of a tablet for inputting coordinates data, a detecting device for detecting the coordinates data inputted by the tablet, a video image data forming device for forming video image data corresponding to input coordinates based on coordinates data by an output signal from the detecting device, a memory for storing the video image data, video signal generating device for generating a video signal from the video image data, output device connected to the video signal generating device for outputting the video signal, a cabinet for accommodating therein elements from the tablet to the video signal generating device, and a plurality of tool selecting buttons formed on the tablet for selecting the output form of the video image data, wherein the video image forming device identifies the designation of the tool selecting buttons and for forming the video image data on the basis of the designated tool. 
     As a third aspect of the present invention, a portable graphic computer apparatus is comprised of a tablet for inputting coordinates data, a detecting device for detecting the coordinates data inputted by the tablet, a video image data forming device for forming video image data corresponding to input coordinates based on coordinates data by an output signal from the detecting device, a memory for storing the video image data, a video signal generating device for generating a video signal from the video image data, an output device connected to the video signal generating device for outputting the video signal, a cabinet for accommodating therein elements from the tablet to the video signal generating device, and a device for mounting on peripheral portions of the tablet in the cabinet a tracing sheet for tracing the tablet. 
     As a fourth aspect of this invention, a portable graphic computer apparatus is comprised of a tablet for inputting coordinates data, a detecting device for detecting the coordinates data inputted by the tablet, a video image data forming device for forming video image data corresponding to input coordinates based on coordinates data by an output signal from the detecting device, a memory for storing the video image data, a video signal generating device for generating a video signal from the video image data, an output device connected to the video signal generating device for outputting the video signal, a cabinet for accommodating therein elements from the tablet to the video signal generating device, and a tracing sheet mounted on the tablet, wherein the tablet has formed at its peripheral portions on the cabinet slots for mounting the tracing sheet, and the tracing sheet has formed thereon insertion portions which are inserted into the slots. 
     As a fifth aspect of the present invention, a tracing sheet is mounted on a tablet of a portable graphic computer apparatus which is comprised of a tablet for inputting coordinates data, a cabinet for accommodating therein the tablet and slots formed on peripheral portions of the tablet in the cabinet. This sheet is characterized by insertion portions which are inserted into the grooves formed at the peripheral portions of the tablet. 
     As a sixth aspect of the present invention, a portable graphic computer apparatus is comprised of a tablet for inputting coordinates data, a detecting device for detecting the coordinates data inputted by the tablet, a video image data forming device for forming video image data corresponding to input coordinates based on coordinates data by an output signal from the detecting device, a memory for storing the video image data, a video signal generating device for generating a video signal from the video image data, a time detecting device for detecting a time interval measured from a timing point at which data is inputted to the tablet last, a sound emanating device for emanating an alarm sound on the basis of the time interval, an output device connected to the video signal generating device for outputting the video signal, and a cabinet for accommodating therein elements from the tablet to the sound emanating device. 
     As a seventh aspect of this invention, a portable graphic computer apparatus is comprised of a tablet for inputting coordinates data, a detecting device for detecting the coordinates data inputted by the tablet, a video image data forming device for forming video image data corresponding to input coordinates based on coordinates data by an output signal from the detecting device, a program memory involved in the video image data forming device and in which a program for forming demonstration video image data for a predetermined time is stored, a time detecting device for detecting a timing point at which the formation of the demonstration video image data is finished or a timing point at which the coordinates data are last inputted to the tablet, a video signal generating device for generating a video signal from the video image data, a time detecting device for detecting a time interval from a timing point at which data is last inputted to the tablet, a sound emanating device for emanating an alarm sound on the basis of the time interval, an output device connected to the video signal generating device for outputting the video signal, and a cabinet for accommodating therein elements from the tablet to the time detecting device, wherein the formation of the demonstration video image data is automatically started on the basis of the time interval. 
     The above and other objects, features and advantages of the present invention will be apparent in the following detailed description of the preferred embodiments to be read in conjunction with the accompanying drawings, in which like reference numerals are used to identify the same or similar parts in the several views. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view illustrating a system arrangement of an embodiment of a portable graphic computer apparatus according to the present invention; 
     FIG. 2 is a plan view illustrating a portable graphic computer according to the embodiment of the present invention; 
     FIGS. 3 and 4 are exploded, perspective views illustrating the portable graphic computer of the embodiment of the present invention, respectively; 
     FIG. 5 is a block circuit diagram of the portable graphic computer of the present invention; 
     FIGS. 6 to  10  are schematic diagrams used to explain an operation of this embodiment, respectively; and 
     FIGS. 11 and 12 are perspective views illustrating other embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will hereinafter be described with reference to the accompanying drawings. In this embodiment, the present invention is applied to a portable graphic computer apparatus which can be used by the children to draw a picture. 
     FIG. 1 shows the arrangement of an overall system of a first embodiment. In FIG. 1, reference numeral  1  generally represents a graphic computer, and  2  a monitor having a video signal input terminal. A video signal output terminal (which will be described later) of the graphic computer  1  and the video signal input terminal of the monitor  2  are coupled via a video cable  3 . The cabinet of the graphic computer  1  is formed of an upper casing  4  and a lower casing  5 . A power switch  6 , a clear button  7 , a sound emanating portion  9  which covers a speaker are provided on the right end portion of the upper casing  4 , and executing buttons  8 A and  8 B are provided on the two side end portions of the upper casing  4 . These power switch  6 , clear button  7 , and executing buttons  8 A,  8 B are respectively independent mechanical switches. 
     Further, a rectangular cut-away portion  4   a  is formed through the center portion of the upper casing  4 , and a tablet  10  is provided beneath the cut-away portion  4   a  as a coordinate input surface of a pressure sensitive type position sensing apparatus. Slots  4   b,    4   c,    4   d  and  4   e  are formed through the recess portion  4   a  at portions where the cut-away portion contacts with the tablet  10 , as shown in FIG.  1 . As will be described later, these slots  4   b  to  4   e  are used to attach a tracing sheet to the tablet  10 . 
     Reference numeral  11  represents an attachment or accessory pen made of a plastic material, and a fundamental operation thereof will be described. When the user draws a locus by slightly touching the tablet  10  with the attachment pen  11  or with the fingertip while pushing the executing button  8 A or  8 B, a pen-shaped cursor  21  is displayed on a picture screen  2   a  of the monitor  2 , and the cursor  21  moves in tandem with the locus of the fingertip or the like to display the locus as an image. Accordingly, the cursor  21  is displayed only during a period in which the user touches the tablet  10  with the accessory pen  11  or with the fingertip. In this case, the executing buttons  8 A,  8 B are provided at both sides of the tablet  10  so that even left-handed children can operate this graphic computer with ease. Further, a clear button  7  is depressed, the video image on the picture screen  2   a  will be erased completely and the graphic computer stands by, in the picture drawing mode. 
     The coordinates input surface of the tablet  10  is, as shown in FIG. 2, divided into a picture-drawing area  10   a  and a menu selecting area  10   c,  and a portion (hatched area) encircled by a bracket and represented by solid circles at a predetermined pitch in the picture-drawing area  10   a  is a picture-making area  10   b.  The aspect ratio of the picture-making area  10   b  is made coincident with the aspect ratio (3:4) of the picture screen of a standard monitor. A pixel ratio that is a ratio between resolution in the longitudinal direction (Y-direction) and resolution in the lateral direction (X-direction) of the input coordinates of the tablet  10  is made coincident with the ratio of pixels of the standard monitor. Therefore, in this embodiment, there is the advantage that, if the user draws a locus of a circle on the picture-making area  10   b  precisely, a picture of a circle is also accurately displayed on the picture screen  2   a  of the monitor  2 . 
     The menu selecting area  10   c  of the tablet  10  is further divided to provide a color selecting area  12  and a tool selecting area  13 . The upper casing  4  has twelve round bores or openings  14  at the color selecting area  12 , and the upper casing  4  also has six openings or slots  15  to  20  at the tool selecting area  13 . If the user slightly touches the tablet  10  through the twelve round opening  14  with the attachment pen  11  or the like, twelve kinds of colors (black/blue/green/yellow/red/white, etc,) will be designated. If the user slightly touches the tablet  10  through the six slots  15  to  20 , then five kinds of tools (fine line, bold line, brush, eraser, stamp) and a cancel function will be designated, respectively. The selected opening in those twelve round openings  14  and six slots  15  to  20  can be discriminated on the basis of the input coordinates to the tablet  10 . 
     As described above, according to this embodiment, color, tool and cancel function are identified on the basis of the input coordinates, and thus the mechanical portion can be simplified. Further there is the advantage that other various functions can be additionally provided only by subdividing or extending the menu selecting area  10   c.  For convenience of explanation, those twelve round openings  14  will be referred to as color selecting buttons  14  and those six slots  15  to  20  will be referred called to a fine line button  15 , a bold line button  16 , a brush button  17 , an eraser button  18 , a stamp button  19  and a cancel button  20 , hereinafter respectively. Functions of these buttons  15  to  20  are as follows: 
     1 fine line button  15  . . . to draw a free curve in fine line of 2×2 dots 
     2 bold line button  16  . . . to draw a free curve by 6×6 columnar dots 
     3 brush button  17  . . . to cause the cursor  21  within the picture screen  2   a  of the monitor  2  to be shaped as a brush to paint the closed area in a designated color 
     4 eraser button  18  . . . to cause the cursor  21  within the picture screen  2   a  of the monitor  2  to be shaped as an eraser to erase a figure drawn 
     5 stamp button  19  . . . to form a video image of a pattern, each being formed of 16×16 dots, selected from 28 kinds of stamps at a desired position 
     6 cancel button  20  . . . to return to the picture of just one procedure before. One procedure means a process which is finished during the depression of the executing button  8 A. 
     The inside structure of the graphic computer  1  of the example shown in FIG. 1 is represented in FIGS. 3 and 4 (illustrating the same in a more enlarged scale than FIG.  3 ). The upper and lower casings,  4  and  5  have sandwiched therebetween a pressure sensitive position sensing apparatus  23  including the tablet  10  and a printed circuit board  22 . The lower case  5  accommodates therein a battery cell or a rechargeable battery as a power source, and reference numeral  5   a  represents a battery cover. The graphic computer  1  of this embodiment may be driven by an AC power source adapter or the like. 
     The arrangement of the pressure sensitive position sensing apparatus  23  will be described with reference to FIG.  4 . Referring to FIG. 4, thin strip electrodes  25  are formed on a first insulating substrate  24  at a pitch Py, and a first pressure sensitive conductive sheet  26  made of a pressure sensitive conductive rubber, a conductive plate  27 , a second pressure sensitive conductive sheet  28  made of a pressure sensitive conductive rubber, and a second insulating substrate  29  having formed on a bottom surface thereof thin strip electrodes  30  at a pitch Px are sequentially laminated on the first insulating substrate  24 . The tablet  10  is mounted on the second insulating substrate  29 . These conductive plate  27 , second insulating substrate  29  and the tablet  10  are respectively made flexible. Px, assumes resolution in the X-direction of the input coordinates of this embodiment, and Py assumes resolution in the Y-direction thereof. A ratio, Px Py is determined to be the same as the pixel ratio of the minimum pixels of a picture screen of a standard monitor. The values of resolutions Px, Py are, for example, about 0.3 mm. 
     The thin strip electrode  30  at one end side in the lateral direction of the second insulating substrate  29  is grounded through a switch circuit  31 , while the thin strip electrode  30  of the other end side is connected to a dc voltage source having a voltage E 1  through a switch circuit  32 . Those thin strip electrodes  30  are connected sequentially with resistors  33  having the same resistance value. Similarly, the thin strip electrode  25  at one end side in the longitudinal direction of the second insulating substrate  24  is grounded through a switch circuit  34 , while the thin strip electrode  25  at the other end side is connected to a dc voltage source having a voltage E 2  through a switch circuit  35 . Those thin strip electrodes  25  are connected sequentially with resistors  36  having the same resistance value. When the user pushes the tablet  10  at a certain position, the pressure sensitive conductive sheets  26  and  28  at that position are conducted. Thus, when the pair of switch circuits  31  and  32  are closed, the conductive plate  27  derives a voltage corresponding to the coordinate of the X-direction, whereas when the pair of switch circuits  34  and  35  are closed, the conductive plate  27  derives a voltage corresponding to the coordinate of the Y-direction. Reference numeral  37  represents a coordinate detecting section. When the pair of switch circuits  31 ,  32  or the pair of switch circuits  34 ,  35  are alternately closed and the voltages generated at the conductive plate  27  are held, the coordinate detecting section  37  generates voltages (Vx, Vy) corresponding to the input coordinates (X, Y) of the tablet  10 . 
     A further detailed arrangement of the pressure sensitive position sensing apparatus  23  shown in the example of FIG. 4 and a modified example thereof are described in Japanese Patent Laid-Open Gazette No. 58-90235. However, the coordinates detecting device of the present invention is not limited to the pressure sensitive type. 
     FIG. 5 shows a circuit arrangement of the graphic computer  1  of this embodiment. In FIG. 5, reference numeral  38  represents a central processing unit (hereinafter referred to as a CPU),  39  a system bus for the CPU  38  and which is comprised of a data bus, an address bus and a control bus,  42  represents a ROM for storing therein a program of the CPU  38  and video data in the demonstration-mode that will be described later, and  43  a RAM. These ROM  42  and RAM  43  are connected to the system bus  39 . Reference numeral  40  represents an analog-to-digital (A/D) converting section, and the CPU  38  is supplied with the voltages (Vx, Vy) corresponding to the input coordinates (X, Y) from the coordinates detecting section  37  via the A/D converting section  40 . If the voltages (Vx, VY) correspond to the coordinates (X, Y) in the picture-making area  10   b  of the tablet  10 , the coordinates (X, Y) are written into the RAM  43 . If the voltages (Vx, Vy) correspond to the coordinates (X, Y) in the menu selecting area  10   c  (see FIG. 2) of the tablet  10 , the CPU  38  identifies the depressed button from the buttons  14 ,  15  to  20  on the basis of the coordinates (X, Y). Color data or tool data corresponding to the identified button is written into the RAM  43 . When the tool buttons  15  to  20  are selected, the CPU  38  will perform the operations corresponding to those tools. Reference numeral  41  represents an input/output (I/O) interface circuit, and the CPU  38  always watches through the I/O interface circuit  41  whether the mechanical switches (the clear button  7  and the executing button  8 A,  8 B in FIG. 1) are operated or not. 
     Reference numeral  44  represents a video processor (hereinafter, referred to as a VDP) connected to the system bus  39 ,  45  a video RAM (VRAM) having a capacity of 2 frames (2 pages), and  46  an NTSC encoder  46 . The VDP  44  reads out data of the input coordinates (X, Y) and color data from the RAM  43  on the basis of commands from the CPU  38  and writes color video data into the VRAM  45  at its corresponding address. Also, it reads out color video data of 1 frame from the VRAM  45  periodically, and supplies the same to the NTSC encoder  46 . The NTSC encoder  46  converts the color video data supplied thereto into a composite video signal CV and supplies the same to a video signal output terminal  47 . In this embodiment, since the VRAM  45  has a storage capacity of 2 pages, in a certain procedure (one procedure means a process carried out during the period in which the executing button  8 A or  8 B is operated as mentioned above), the VDP  44  writes and reads video data in the region of, for example, the first page. In the next procedure, after moving the video data of the first page into the region of second page completely, the VDP  44  writes and reads video data in the region of the second page. If the CPU  38  issues a cancel command to the VDP  44  when the cancel button  20  of the tool selecting area  13  in the tablet  10  is pushed, the VDP  44  again reads the video data in the first page region of the VRAM  45 , and writes the video data into the first page region when the CPU  38  is supplied with coordinates input. This means the picture in the picture screen  2   a  of the monitor  2  returns to a picture of one procedure before by operating the cancel button  20 . There is then the advantage that, when the user draws a wrong picture in the picture drawing mode, the original picture can be recovered in a one-touch fashion. 
     In FIG. 5, reference numeral  48  represents a counter,  49  an alarm circuit, and  50  a speaker provided for the sound emanating section  9  (see FIG.  1 ). The counter  48  keeps counting the clock pulse from the CPU  38  and can clear the count value at any time by a clear pulse from the CPU  38 . When the count value of the counter  48  reaches the value of 5 minutes, i.e. the clear pulse has not been supplied to the counter  48  from the CPU  38  for five minutes, the counter  48  supplies an alarm signal AL to the CPU  38 . During the normal drawing mode, the CPU  38  supplies an alarm operation signal to the alarm circuit  49  through the I/O interface circuit  41  in response to the alarm signal AL. The alarm circuit  49  is comprised of a timer, an oscillator, a synthesizer, a power amplifier or the like, and supplies a signal corresponding to predetermined sound, melody, or a message to the speaker  50  for only two minutes in response to the alarm operation command from the CPU  38 . These counter  48 , alarm circuit  49  and speaker  50  are mainly provided in order to generate an alarm sound by which the user can be protected from leaving the power switch in its ON state. 
     Further, in this embodiment, the alarm circuit  49  is not limited to the alarm operation and is utilized in the normal sound emanating operation via the interface circuit  41 . For example, if the user selects the color selecting button  14  and the tool selecting buttons  15  to  20  and the like, then the alarm circuit  49  is operated so that the speaker  50  emanates a predetermined touch-sound. 
     When the graphic computer  1  of this embodiment is used, the video signal output terminal of the graphic computer  1  is just coupled to the video signal input terminal of the monitor  2  via the video cable  3 . When the user turns ON the power switch  6  by moving a slidable contact, the picture screen  2   a  of the monitor  2  displays thereon for a predetermined period of time a demonstration display which teaches the user an example of how to use the graphic computer  1  of the embodiment. More specifically, a pen as a cursor is displayed on the picture screen  2   a  to draw a predetermined picture or an eraser as a cursor is displayed thereon to erase the picture, whereby the user can understand how to use the graphic computer. 
     A demonstration display program is written in the ROM  42  and includes color data, tool data and a series of data of the input coordinates (X, Y) or the like. The CPU  38  sequentially reads these data and moves the same to the RAM  43  and the VDP  44  produces video data corresponding to the data of the RAM  43 , whereby the demonstration display is carried out as though the operator draws a locus on the tablet  10  in actual practice. 
     There is then the substantial advantage that the capacity that the demonstration display program shares in the ROM  42  can be relatively reduced. 
     If the user operates the clear button  7  or if the user operates the executing button  8 A or  8 B or if the user inputs coordinates to the tablet  10  (including the menu selecting area  10   c ) during the demonstration display mode, then the graphic computer  1  of this embodiment is set in “picture drawing model”, whereby the picture displayed on the picture screen  2   a  of the monitor  2  is thoroughly erased and the graphic computer is set in the standby mode awaiting the user&#39;s input. After the user designates the tool by pushing the color button  14  the fine line button  15  or the bold line button  16  with the accessory pen  11  or the fingertip and the like, if the user freely draws a locus by slightly touching the picture making area  10   b  with the accessory pen  11  under the condition that the executing button  8 A or  8 B is depressed, a figure similar to the locus with designated color and thickness can be drawn on the picture screen  2   a  of the monitor  2  by the cursor  21 . In this case, if the executing button  8 A or  8 B is not depressed, the cursor  21  will move in the background of the previously-drawn picture on the picture screen  2   a.  Thus, the locus of the cursor  21  is not displayed as a picture until the executing button  8 A or  8 B is operated. Accordingly, the position of the cursor can be determined precisely when the user moves from a certain step, for example, of the drawing to the next stop. 
     If the user depresses the brush button  17  in the menu selecting area  10   c,  the cursor  21  is shaped as a brush so that, when the user slightly touches the picture making area  10   b  with the accessory pen  11  or the like, the user can paint in a designated color the inside of a closed figure (circle, rectangle or the like) near the locus of the brush-shaped cursor within the previously-drawn picture. 
     If the user depresses the eraser button  18  in the menu selecting area  10   c  and slightly touches the picture-making area  10   b  with the accessory pen  11  or the like, an eraser-shaped cursor  21   a  is displayed in the background of the previously drawn picture on the picture screen  2   a  of the monitor  2  as shown in FIG. 6A so that, when the user depresses the executing button  8 A or  8 B while moving the attachment pen  11  or the like, the previously-drawn picture can be erased partly. If the picture is erased too much, the picture screen  2   a  can be returned to the previous picture, produced before, by depressing the cancel button  20  in the menu selecting area  10   c  as shown in FIG.  6 B. 
     If the user depresses the stamp button  19  in the menu selecting area  10   c,  as shown in FIG. 7, several kinds of stamp characters  51  are displayed in the upper portion of the picture screen  2   a  of the monitor  2 . For example, if the user pushes the tablet  10  at a portion corresponding to a desired character in the stamp characters  51 , then that character is selected as a cursor. If the user depresses the executing button  8 A or  8 B while slightly touching the tablet  10  with the accessory pen  11  or the like, then a desired stamp character will be displayed on the picture screen at its portion designated by the depression of the executing button  8 A or  8 B. Further, the stamp character can be superimposed upon the previously-drawn picture. 
     As described above, in the graphic computer  1  of this embodiment, the pressure sensitive type position sensing apparatus  23  involving the tablet  10 , the CPU  38 , the VDP  44 , the VRAM  45 , and the NTSC encoder  46  or the like are formed as one body and the picture is formed with ease only by connecting the graphic computer  1  and the monitor  2  via the video cable  3 . Therefore, the arrangement of this system can be simplified and children can use this graphic computer with ease. Thus, the system of this embodiment is suitable for the children to draw a picture. 
     On picture-making area  10   b  of the tablet  10  of the graphic computer  1  in this embodiment, there can be loaded a play card  52  that is a flexible sheet in which a predetermined character  53  is printed on one or both surfaces thereof as shown in FIG.  8 . This play card  52  is substantially rectangular, in which two protruding portions (inserting portions)  52   b,    52   c  are formed on an upper side portion thereof while two protruding portions (inserting portions)  52   d ,  52   e  are formed on a lower side portion thereof and a semicircular notch  52   a  for ejecting the play card is formed on a left side portion thereof, respectively. 
     When the play card  52  is loaded on the graphic computer  1  of this embodiment, the inserting portions  52   b  and  52   c  of the upper side portion of the play card  52  are respectively inserted into the slots  4   b  and  4   c  adjacent to the tablet  10  on the upper casing  4  of the graphic computer  1  while the play card  52  is slightly deformed as shown in FIG.  9 . Then, the inserting portions  52   d  and  52   e  of the lower side portion of the play card  52  are respectively inserted into the slots  4   d  and  4   e  of the upper casing  4  (see FIG.  1 ), whereby the play card  52  is stably loaded on the tablet  10  as shown in FIG.  10 . 
     As a method for using the play card  52 , there might be considered “tracing” and “puzzle game” or the like. If the user selects the “tracing”, the respective portions of the character  53  of the play card  52  shown in FIG. 8 are marked with, for example, numerals such as 1′, 2′, 3′, . . . . In some case, the user traces the respective portions of the character  53  in the order of 1′, 3′, 5′, 8′, . . . . In other case, the user traces the respective portions of the character  53  in the order of 1′, 2′, 4′, 7′, . . . so that, for example, different animal characters are respectively displayed on the picture screen  2   a  of the monitor  2 . In other words, a kind of a hidden picture search play becomes possible. 
     In the case of “puzzle game”, words having ciphers are printed on the play card  52  in advance and the user writes words while guessing the ciphers. 
     As described above, if the play card  52  of this embodiment is used, the system in the example of FIG. 1 can be applied not only to the picture drawing but also to a sophisticated play or to a kind of learning. In this case, since the play card  52  of this embodiment is provided with the inserting portions  52   b  to  52   e  while the slots  4   b  to  4   e  are formed on the portion in which the upper case  4  of the graphic computer  1  contacts with the tablet  10  the play card  52  can be loaded on the graphic computer with ease. Moreover, since the play card  52  is provided with the notch  52   a  for ejecting the play card the play card  52  can be ejected from the graphic computer  1  with ease. 
     Instead of forming the grooves  4   b  to  4   e  on the upper casing  4 , a leaf spring may be provided on the edge portion of the recess  4   a  of the upper casing  4  in order to fix the peripheral section of the play card  52 . In that case, the inserting portions  52   b  to  52   e  can be removed from the play card  52 . 
     Operations of the counter  48  and the alarm circuit  49  in this embodiment will be described. In the normal picture drawing mode, the counter  48  keeps counting the clock pulse from the CPU  38 . Each time the coordinates data (involving the menu selecting area  10   c ) are inputted on the tablet  10  or the clear button  7  is depressed or the executing button  8 A or  8 B is depressed, the CPU  38  causes the counter  48  to clear the count value. When the demonstration display is carried out after the graphic computer is powered, the CPU  38  holds the condition of the counter  48  in which the count value of the counter  48  is cleared. In the normal picture drawing mode, if the user has neither touched the tablet  10  nor the user has depressed any mechanical switch for five minutes, such as when the power switch is not turned OFF inadvertently (including the case in which the user has not carried out any operation for five minutes after the completion of the demonstration display), then the count value of the counter  48  reaches the value equivalent to five minutes so that the counter  48  supplies the alarm signal AL to the CPU  38 . 
     When receiving the alarm signal AL, the CPU  38  causes the alarm circuit  49  to perform the alarm operation through the I/O interface circuit  41 , thereby alarm sound, such as predetermined sound, melody, message etc., being emanated from the speaker  50  for two minutes. Thus, the user can be protected from leaving the power switch in its ON state, inadvertently. If the power switch  6  is not turned OFF during a time period of two minutes while the speaker  50  emanating sound, the CPU  38  holds the condition of the counter  48  in which the count value of the counter  48  is cleared. 
     The graphic computer  1  of this embodiment has programmed therein a demonstration mode (shop display mode) in addition to the above-described normal mode. The demonstration mode is utilized to display the system shown in FIG. 1 so that a customer can freely operate this system at the shop window of the shop. When the graphic computer is set in the demonstration mode, the user slides the slidable contact to turn ON the power switch  6  while depressing the clear button  7 . In the demonstration mode, the demonstration display begins after the graphic computer is powered. During the demonstration mode, if the user depresses the clear button  7 , the executing button  8 A or  8 B or if the user inputs coordinate data into the tablet  10 , then the displayed picture is cleared and the graphic computer is set in the picture drawing mode, in which mode the user can draw a picture freely, similarly to the normal mode. 
     In this demonstration mode, the program is made so that if the user does not operate the graphic computer for five minutes until the demonstration display is ended after the power switch is turned ON, or if the user does not operate the graphic computer for 5 minutes during the picture drawing mode after the demonstration display is ended, the picture displayed on the picture screen  2   a  of the monitor  2  is cleared completely and the demonstration display is started once again. More specifically, the CPU  38 , supplied with the alarm signal AL from the counter  48  when the demonstration mode is set, executes the demonstration display program once again without operating the alarm circuit  48 . If the user operates the graphic computer during the demonstration display mode, the picture displayed on the picture screen is cleared and the graphic computer is set in the drawing mode. This means that, if the graphic computer is not operated at all for five minutes after the customer freely draws a picture when the system in the example of FIG. 1 is exhibited at a shop window, the picture drawn by the customer is automatically erased and the demonstration display is started once again. Therefore, according to this demonstration mode, when the graphic computer is exhibited at the shop front, the salesman need not clear the picture drawn by the customer, thus making the graphic computer easy to handle. 
     The graphic computer  1  may incorporate therein a color or monochromatic printer (dot printer, printer-plotter, etc.) as shown in FIG. 11, so that the user can print a desired picture  54  at any time. In order to complement the ROM  42  in FIG. 5, an IC card in which an application software is written or a voice IC card as a pulse signal generator or an FM sound source, etc., may be provided as an attachable/detachable card  55 . Alternatively, the graphic computer may incorporate therein a disk driving apparatus for a 2-inch or 3.5-inch floppy disk. 
     While in the above embodiment, the graphic computer  1  and the monitor  2  are provided independently, as shown in FIG. 12, the monitor  2  may be replaced with a liquid crystal display  56 . This liquid crystal display  56  may be mounted on the cabinet of the graphic computer  1  so as to become freely rotatable. If the graphic computer  1  and the liquid crystal display  56  are unitarily formed in this way, the overall arrangement can be more simplified, and the graphic computer can be used conveniently because the coordinates input section and the image display section are located close to each other. Further, the liquid crystal display  56  may be replaced with an EL panel. 
     While in the above described embodiment, the composite video signal CV of the graphic computer  1  is supplied to the monitor  2  or the like, the composite video signal CV may be directly supplied to a video tape recorder or to an electronic camera, whereby the signal may be recorded in a video tape, a floppy disk or the like. 
     Further, a predetermined melody and message may be emanated from the speaker while the demonstration picture is displayed on the picture screen of the television monitor. 
     According to the present invention, constituent parts except for the output device are accommodated in the cabinet and made unitary so that the overall arrangement of the apparatus can be miniaturized. Also, the apparatus can be used only by connecting the video signal forming circuit to the output device through, for example, the video cable. Thus, children can use this graphic computer with ease. 
     Further, since not only the coordinates are inputted by the coordinates detecting device but also the tool selecting button and the color selecting button on the tablet are designated by the coordinates detecting device, the mechanical portion of the present invention can be simplified and the functions thereof can be extended. 
     If the display device is attached to the cabinet as the output device, then the overall arrangement of the invention can be simplified more. Also, the coordinates portion and the video image display portion are provided close to each other so that the portable graphic computer apparatus can be made easier to handle. 
     If no data is inputted to the tablet during a certain period of time continuously or if the graphic computer apparatus is not operated at all after the demonstration display mode is ended, then the alarm sound is emanated from the speaker so that the user can be prevented from inadvertently leaving the power switch in its ON state. 
     Further, if a predetermined time is passed after the formation of the demonstration display mode video image data is ended or if a predetermined time is passed from a time point in which data are inputted to the tablet last, the formation of the demonstration display mode video image data is started so that the user need not carry out the operation for the demonstration display mode or the like. Therefore, the portable graphic computer apparatus of the invention is suitably exhibited at the shop front or the like for demonstration. 
     The overall arrangement of the portable graphic computer apparatus of the invention can be made compact in size and can be utilized by the children with ease. Further, since the tracing paper is fixedly mounted on the tablet and the tracing sheet is utilized as a kind of teaching material. There is then the advantage that this portable graphic computer apparatus can be made more useful. 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments and that various modifications and variations could be effected by one skilled in the art without departing from the spirit or scope of the novel concepts of the invention as defined in the appended claims.