Electronic blackboard apparatus

Abstract

An electronic blackboard apparatus comprises an electronic blackboard unit, a writing instrument, a position-detecting control unit, and an output section. When video information such as characters and figures is depicted on a writing surface by means of the writing instrument, a magnetic bias with a locus corresponding to the video information is simultaneously applied to a position-detecting tablet of the electronic blackboard unit. Position coordinates thereof are computed by the position-detecting control unit and converted into electric signals. Similarly, when the video information on the writing surface is erased by means of the eraser, a magnetic bias with a locus corresponding to the erased video information is simultaneously applied to the position-detecting tablet. Position coordinates thereof are calculated by the position-detecting control unit and converted into electric signals. On the basis of these electric signals, the video information on the writing surface is output from the output section as a hard-copy image or as a display image.

What is claimed is: 
     
       1. An electronic blackboard apparatus, comprising: an electronic blackboard unit having a surface plate made of a non-magnet material, the surface of which is formed as a writing surface capable of being used repeatedly, and a position-detecting tablet for detecting position coordinates of a local magnetic bias applied via said surface plate;   a writing instrument having a core member for displaying video information including characters and figure on said writing surface and a magnetism generator for applying a magnetic bias to said position-detecting tablet when said core member is in contact with said writing surface;   an eraser having an erasing member for erasing said video information including said characters and figure on said writing surface and a magnetism generator for applying a magnetic bias to said position-detecting tablet when said erasing member is in contact within said writing surface;   a position detecting control unit for driving said position-detecting tablet and for computing the position coordinates of said writing instrument and said eraser; and   an output section for outputting said video information of said writing surface.   
     
     
       2. An electronic blackboard apparatus according to claim 1, wherein said position-detecting tablet is comprised of: first magnetostrictive transmission medium elements constituting an assembly of a plurality of magnetostrictive transmission medium elements, each of which is located on the rear side of said surface plate, is arranged in parallel with each other, and constitutes a first array layer substantially parallel with said writing surface on said rear side of said surface plate;   second magnetostrictive transmission medium elements having an arrangement equivalent to that of said first magnetostrictive transmission medium elements and constituting a second array layer superposed on said first array layer, each of said second magnetostrictive transmission medium elements being substantially perpendicular to said first magnetostrictive transmission medium elements;   exciting coils constituted by a set of coils wound around each end of said first magnetostrictive transmission medium elements and adapted to commonly excite said each end and a coil wound around each end of said second magnetostrictive transmission medium elements and adapted to commonly excite said each end; and   detection coils constituted by a set of coils respectively wound around each of said first magnetostrictive transmission medium elements over the entire length thereof and adapted to fetch induced voltages based on magnetostrictive vibration waves in said first magnetostrictive transmission medium elements and coils respectively wound around each of said second magnetostrictive transmission medium elements over the entire length thereof and adapted to fetch induced voltages based on magnetostrictive vibration waves in said second magnetostrictive transmission medium elements; and said position-detecting control unit is comprised of:   a pulse oscillator for supplying a pulse current to said exciting coils at an appropriate timing; and   a computing unit for measuring a time from the time of said excitation until the time of fluctuations in said induced voltages of said detection coils on the basis of said fluctuations at the time when said magneto-vibration waves generated from said each end of said first or second magnetostrictive transmission medium elements reach the position of contact of said writing instrument at the time of said excitation.   
     
     
       3. An eraser for use with an electronic blackboard in which each position in a writing region is defined by X coordinates and Y coordinates using each one end of said writing region in the X- and Y-directions as reference positions and reaching each other end thereof, a writing position is indicated with the use of a writing instrument, and a written image is processed electronically, said eraser comprising: position-indicating means provided at the vicinity of opposite end portions of the surfaces of an erasing member contacting a writing surface and adapted to indicate first and second positions; and   inclination-discriminating means for discriminating to which side a straight line connecting said first and second positions is inclined using an X-axis or a Y-axis on said writing surface as a reference line.   
     
     
       4. An eraser for use with an electronic blackboard in which each position in a writing region is defined by X coordinates and Y coordinates using each one end of said writing region in the X- and Y-directions as reference positions and reaching each other end thereof, a writing position is indicated with the use of a writing instrument, and a written image is processed electronically, said eraser comprising: position-indicating means provided at the vicinity of opposite end portions of the surfaces of an erasing member contacting a writing surface and adapted to indicate first and second positions;   inclination-discriminating means for discriminating to which side a straight line connecting said first and second positions is inclined using an X-axis or a Y-axis on said writing surface as a reference line; and   at least two switches actuating when said erasing member comes into contact with said writing surface and adapted to indicate an erasing position by a combination with an indication of said position-indicating means.   
     
     
       5. An eraser for an electronic blackboard according to claim 4, wherein a switch for obtaining a signal corresponding to a pressing force is used to enlarge or reduce the region of an erasing portion in correspondence with said pressing force. .Iadd. 
     
     
       6.  An eraser for removing a line from a display surface on which the line is written while signalling the location of the eraser to a position detector for an implement, the detector establishing magnetic fields for position detection, comprising a housing, the housing including: an exterior eraser surface for enabling the line to be erased from the display surface,   a structure positioned behind and in proximity to the eraser surface for deriving a field that interacts with the position detector to enable the position detector to derive signals for indicating the eraser position on the display surface, and   switch means activated in response to the eraser surface being in an erase position on the display surface for causing a response to be coupled from the housing to the detector to indicate the presence of the eraser surface on the display surface. .Iaddend. .Iadd.7. The eraser of claim 6 wherein the structure is not powered by an electric power supply. .Iaddend. .Iadd.8. The eraser of claim 7 wherein a pair of said structures are provided in proximity to opposite ends of the eraser surface, each of said structures deriving a separate field that separately interacts with the detector to provide an indication of the region spanned by the eraser surface between the opposite ends thereof. .Iaddend. .Iadd.9. The eraser of claim 8 wherein a separate pressure responsive switch is associated with each of said structures, said switches being arranged so that (a) both of said switches are activated to a first state in response to the eraser surface between the structures being pressed flat against the display surface, and (b) only the switch in proximity to one of said ends is activated to the first state in response to said end being pressed against the display surface to the exclusion of the other of said ends. .Iaddend. .Iadd.10. The eraser of claim 6 wherein a pair of said structures are provided in proximity to opposite ends of the eraser surface, each of said structures deriving a separate field that separately interacts with the detector to provide an indication of the region spanned by the eraser surface between the opposite ends thereof. .Iaddend. .Iadd.11. In combination, a writable and erasable display surface on which lines can be mechanically written and erased, a two coordinate position detector for an implement positioned on the display surface, said detector including means for establishing position detecting magnetic fields in the two coordinate directions,   a pen for inscribing a line on the display surface, the pen including: a marker material for enabling a line to be drawn on the display surface,   a first structure for deriving a first field that interacts with the detector to enable the position detector to derive signals indicative of the pen position on the display surface, and   first switch means activated in response to the marker material being in a write position on the display surface for causing a response to be coupled from the pen to the detector to indicate the presence of the marker material on the display surface;     an eraser including: an eraser surface for enabling the line to be erased from the display surface,   a structure positioned behind and in proximity to the eraser surface for deriving a second field that interacts with the position detector to enable the position detector to derive signals for indicating the eraser position on the display surface,   second switch means activated in response to the eraser surface being in an erase position on the display surface for causing a response to be coupled from the housing to the detector to indicate the presence of the eraser surface on the display surface, and   means responsive to the signals for deriving an output signal indicative of the position of the line mechanically written on the display surface as modified by the position of the eraser surface on the display surface. .Iaddend. .Iadd.12. The combination of claim 11 further including a two-coordinate display responsive to the output signal for displaying the line written on and erased from the display surface. .Iaddend. .Iadd.13. The combination of claim 11 wherein said structures in the pen and eraser are not powered by an electric power supply. .Iaddend. .Iadd.14. The combination of claim 11 wherein said eraser includes a pair of said structures in proximity to opposite ends of the eraser surface, each of said structures deriving a separate field that separately interacts with the detector to provide an indication of the region spanned by the eraser surface between the opposite ends thereof, said detector and signal deriving means being responsive to the separate fields so the output signal is indicative of the span of the eraser surface between the opposite ends thereof. .Iaddend. .Iadd.15. The combination of claim 14 wherein said eraser includes a separate pressure responsive switch associated with each of said structures, said switches being arranged so that (a) both of said switches are activated to a first state in response to the eraser surface between the structures being pressed flat against the display surface, and (b) only the switch in proximity to one of said ends is activated to the first state in response to said end being pressed against the display surface to the exclusion of the other of said ends, said detector and signal deriving means being responsive to separate responses derived in response to different combinations of the switches being activated to the first state. .Iaddend. .Iadd.16. The combination of claim 14 further including a two-coordinate display responsive to the output signal for displaying the line written on and erased from the display surface. .Iaddend. .Iadd.17. The combination of claim 11 further including a display for forming an image of a replica of the drawn and erased line in response to the output signal. .Iaddend. .Iadd.18. A method of drawing and erasing a line on a display surface and for deriving a signal indicative of the drawn line image as affected by the erasing operation, a field sensing two-coordinate position detector being associated with the display surface, comprising the steps of     (1) drawing the line with a pen having (a) a marker for the surface (b) a first magnetic field affecting structure, and (c) a first pressure responsive switch,   (2) erasing at least a portion of the drawn line with an eraser for the line drawn by the marker on the display surface, the eraser including a second magnetic field affecting structure and a second pressure responsive switch,   (3) activating the first switch to a first state during step (1) so that a first response is derived as the magnetic field of the first structure is interacting with the field sensing detector,   (4) activating the second switch to a first state during step (2) so that a second response is derived as the magnetic field of the second structure is interacting with the field sensing detector, and   (5) responding to the first and second responses and the interaction of the magnetic fields of the first and second structures with the field sensed by the position detector to derive the signal. .Iaddend. .Iadd.19. The method of claim 18 wherein the eraser includes a pair of said structures in proximity to opposite ends of the eraser surface, responding to separate interactions between said pair of structures and the field sensors of the position detector while said eraser surface is pressed against the display surface to activate the switch means of the eraser to modify the signal to indicate that the distance spanned by the eraser between the ends thereof is not part of the line. .Iaddend. .Iadd.20. The method of claim 18 further comprising sequentially energizing magnetic fields in said coordinate directions, the structures interacting with the magnetic fields to modify the magnetic fields as a function of the pen and eraser positions, the signal being derived in response to the modified magnetic fields. .Iaddend. .Iadd.21. The method of claim 18 further including displaying a replica of the drawn and erased line in response to the signal. .Iaddend. .Iadd.22. An eraser comprising a housing, the housing including:   an exterior eraser surface for erasing a line drawn with a marker from a display surface,   a pair of magnetic field affecting structures in proximity to opposite ends of the eraser surface, and   a switch associated with each of said structures, said switches being arranged so that (a) both of said switches are activated to a first state in response to the eraser surface between the structures being pressed flat against the display surface, and (b) only the switch in proximity to one of said ends is activated to the first state in response to said end being pressed against the display surface to the exclusion of the other of said ends. .Iaddend. .Iadd.23. The eraser of claim 22 further including means responsive to different combinations of the switches being activated to the first state for deriving different responses indicative of the different combinations of the switches. .Iaddend. .Iadd.24. An implement for mechanically inscribing or mechanically erasing a line on a display surface while simultaneously enabling the position of the implement to be signalled to a tablet including two coordinate direction magnetic field responsive elements, the implement comprising a housing, the housing including:   a first structure at one region of the housing adapted to bear against the display surface for mechanically changing an image on the display surface while the one region bears against the display surface,   a second structure in proximity to the one region for affecting the magnetic field responsive elements of the tablet while the one region bears against the display surface, and a pressure responsive switch coupled with said one region so that the switch is activated from a normal state to another state in response to the one region bearing against the display surface. .Iaddend. .Iadd.25. The implement of claim 24 wherein the housing is formed as a pen and the first structure includes material for mechanically marking the display surface. .Iaddend. .Iadd.26. The implement of claim 24 wherein the housing is formed as an eraser and the first structure includes material for mechanically erasing a mechanical image from the display surface. .Iaddend. .Iadd.27. The implement of claim 26 wherein a pair of said first structures are provided in proximity to opposite ends of the eraser surface, each of said structures deriving a separate field that separately interacts with the detector to provide an indication of the region spanned by the eraser surface between the opposite ends thereof. .Iaddend. .Iadd.28. The implement of claim 27 wherein a separate pressure responsive switch is associated with each of said structures, said switches being arranged so that (a) both of said switches are activated to a first state in response to the eraser surface between the structures being pressed flat against the display surface, and (b) only the switch in proximity to one of said ends is activated to the first state in response to said end being pressed against the display surface to the exclusion of the other of said ends. .Iaddend. .Iadd.29. The implement of claim 24 wherein the second structure is not powered by an electric power supply. .Iaddend. .Iadd.30. The implement of claim 29 wherein the second structure supplies a magnetic field to the magnetic   
     
     
        field responsive elements of the tablet. .Iaddend. .Iadd.31.  The combination of claim 11 wherein said two coordinate position detector includes means for deriving a magnetic field, said eraser and pen including structures for modifying the magnetic field derived by the position detector, the position detector including means for sensing the modified magnetic field and for deriving a signal indicative of the location of the modified magnetic field. .Iaddend. .Iadd.32. The combination of claim 31 wherein said magnetic field deriving means includes, for each coordinate direction, plural magnetostrictive transmission lines and means for inducing an AC magnetic field in each of said lines. .Iaddend. .Iadd.33. The combination of claim 32 wherein the magnetostrictive lines for each separate coordinate direction are parallel to each other, the lines for the two directions being at right angles to each other. .Iaddend. .Iadd.34. The combination of claim 32 wherein the means for inducing includes an exciting coil at one end of each of said lines. .Iaddend. .Iadd.35. The combination of claim 34 wherein the same exciting coil is wound on each of said lines in each of said coordinate directions so as to commonly excite the different lines in each of said coordinate directions. .Iaddend. .Iadd.36. The combination of claim 35 further including a bias magnet for each of said lines. .Iaddend. .Iadd.37. The combination of claim 32 wherein the means for sensing the modified magnetic field includes a detecting coil on each of said lines. .Iaddend. .Iadd.38. A method of causing a line to be written on and erased from a display in response to signals derived from movement relative to a tablet of first and second implements associated with writing and erasing on the display, a field sensing two-coordinate position detector being associated with the tablet, the first and second implements respectively having first and second magnetic field affecting structures and first and second switches comprising the steps of: activating the first switch to a first state as the first implement is being moved in proximity to the tablet so that a first response is derived as the magnetic field affecting structure of the first implement is interacting with the field sensing detector,   activating the second switch to a first state as the second implement is being moved in proximity to the tablet so that a second response is derived as the magnetic field affecting structure of the second implement is interacting with the field sensing detector,   responding to the first and second responses to derive the signals, and   responding to the signals to reproduce on the display a replica of the movement of the first implement as modified by movement of the second implement such that movement of the first implement is displayed on the display as a written image and movement of the second implement results in eraser of the written image at positions of the second implement overlapping positions of the first implement while the first and second switches are activated to the first state. .Iaddend. .Iadd.39. In combination,   a two-coordinate display on which lines can be written and erased,   a tablet including a two-coordinate position detector for implements positioned in proximity to the tablet, said detector including means for establishing position detecting magnetic fields in the two coordinate directions,   a first implement associated with writing an image on the display, the first implement including: a first switch adapted to be activated while the first implement is in proximity to the tablet, and   a first structure affecting the detector position detecting magnetic fields while the first implement is in proximity to the tablet;   a second implement associated with erasing an image from the display, the second implement including a second switch adapted to be activated while the second embodiment is in proximity to the tablet;     a second structure affecting the detector position detecting magnetic fields while the second implement is in proximity to the tablet; and   means responsive to magnetic field responses from the detector while the implements are moved in proximity to the tablet and while the switches are closed for activating the display so that a replica of the movement of the first implement in proximity to the tablet while the first switch is activated is written as an image on the display and the written image is erased from a portion of the display corresponding with the second implement overlapping the first implement while the second switch is activated in response to movement of the second implement in proximity to the tablet while the second switch is activated. .Iaddend. .Iadd.40. The combination of claim 39 wherein the first and second implements are cordless. .Iaddend.