JPS6037925B2 - Scanning method of electronic whiteboard system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning method for an electronic blackboard system, and more particularly, the present invention relates to a scanning method for an electronic blackboard system, and more particularly, the present invention relates to a scanning method for an electronic blackboard system, and in particular, the coordinates of a writing point such as a character written with a writing smell such as chalk on a blackboard on which matrix electrodes are arranged can be displayed on a cathode ray tube display or the like. The present invention relates to a scanning method for an electronic blackboard system that transmits images of characters and the like corresponding to handwritten content to a display device of the electronic whiteboard system and reproduces images of characters and the like corresponding to handwritten content.

This electronic blackboard system transmits the coordinates of the pressure point of a character written with a writing instrument such as chalk to a remote location via a telephone line, and displays images of characters on a display device such as a cathode ray tube display. It is to be displayed.

By the way, if we assume the size of the Kurosaka to be used is about 1 in length and 1.3 in width, and the resolution is 2 in width, and taking into account the retrace time during scanning, the number of electrodes is about 490 in length and 1 in width. It becomes necessary.

If the writing speed is about 40 skins/S, scanning the pixels on the 2nd side on the blackboard requires 2 skins/4 skins/S = 5m.
Just scan with S. Therefore, it is difficult to scan all pixels. ≠56・Misaki Z scanning frequency is required.

However, the circuit configuration of a device using such a high scanning frequency is extremely difficult.

In addition, since the blackboard is wide, it has the disadvantage that the pen pressure cannot be accurately tracked using a simple tracking operation. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a scanning method for an electronic whiteboard system that can be realized with a simple circuit configuration and can track pen pressure with high accuracy.

In order to achieve such an object, the present invention sets a frame including the coordinates of the first pen pressure point in the area where the coordinates of the pen pressure point are detected, and estimates the frame based on the vector of the coordinates of the pen pressure point. This is to move it in the direction that it will move. Hereinafter, the present invention will be explained in detail using the drawings. FIG. 1 is a top view of a blackboard used in an embodiment of the present invention, and FIG. 2 is a cross-sectional view.

In the figure, 1 and 2 are a horizontal electrode group and a vertical electrode group arranged in a matrix, and an elastic conductor sheet 3 is inserted between these electrode groups. The elastic conductor sheet 3 is a composite material in which uniform conductive fibers (acicular carbon fibers) 3b are embedded in a sheet-like silicone rubber 3a, which is an insulator, as shown in a cross-sectional view in FIG. When pressure is applied as shown by the arrow, the silicone rubber 3a deforms and the carbon fibers protrude and are pressed against both sides of the sheet, changing the resistance value. In FIG. 2, when the choke 4 is pressed down, the resistance value of the elastic conductor sheet 3 changes, and this change is applied from the horizontal electrode group 1 and the vertical electrode group 2.

In this case, the distance d between adjacent electrodes is the resolution limit.

FIG. 4 is a block diagram showing an embodiment of the present invention, which is a pressure sensor type blackboard having the structure shown in FIGS. 1 and 2. FIG.

The vertical electrode group 2 of this blackboard 10 is an x-coordinate switch circuit 11
The horizontal electrode group 1 is connected to a y-coordinate switch circuit 12. And these x coordinate switch circuits 1
1 and the y-coordinate switch circuit 12 perform scanning according to a control signal from the scan control circuit 13, and when the point to which pen pressure is applied is scanned, the x-coordinate switch circuit 11 outputs a detection signal. The output of the x-coordinate switch circuit 11 is supplied to the maximum pen pressure point detection circuit 15 via an analog-to-digital conversion section (hereinafter referred to as A/○ conversion section) 14, and the output of this maximum pen pressure detection circuit 15 is It is supplied to the computer 6. A control logic 17 decodes signals from the microcomputer 16 to control the scan control circuit 13 or the memory circuit control section 18. On the other hand, the memory circuits 19 and 20 have a scan control circuit 13
, various types of information are supplied from the microcomputer 16, and reading and reading of the information is performed under the control of the storage circuit control section 18.

Note that 21 is a transmitter that converts the signal sent from the microcomputer 6 into a signal suitable for transmission over the telephone line L, and 22 is a display unit 23 that converts the signal sent from the microcomputer 6 into a signal suitable for transmission over the telephone line L.
This is a receiving section that converts the signal into a signal that is compatible with the standard. The operation of the electronic whiteboard system according to the present invention configured as described above is as follows.

Before going into detailed explanation, first, in order to facilitate understanding of the present invention, the general operation will be explained with reference to the circuit diagrams shown in FIGS. 5 and 6. Note that each magazine issue is the same as in Figure 4. When no pen pressure is applied on the blackboard 10, the fifth
As shown in the figure, scanning is performed in which all the y-coordinate switch circuits 12 are turned on, and the x-coordinate switch circuits 11 are sequentially turned on one by one.

When pen pressure is applied to the point at coordinates (Xo, Yo) at a certain point, a detection signal is obtained from the x-coordinate switch circuit 11 at the time when the x-coordinate switch circuit 11 scans x=Xo.

When this detection signal is obtained, the x coordinate switch circuit is set to x:
It is fixed at Xo, and the y-coordinate switch circuit 12 is sequentially scanned as shown in FIG. Then, when the y-coordinate switch circuit 12 scans y=Yo, a detection signal is again obtained from the x-coordinate switch circuit 11. Now that the initial writing pressure point coordinates x=Xo, y=Yo have been detected, next, based on this point, only the electrodes in a predetermined range are scanned one pixel at a time in the horizontal and vertical directions.

This allows detailed partial scanning around x=Xo, y=Yo. In this case, for example, if a range of ±8 pixels is scanned around x=Xo, y=Yo, and the scanning speed of one pixel is hS, the scanning frequency will be as follows. Shunshu 7
: Pentapod HZ This value is the scanning frequency of 56.0 when scanning one pixel at a time. 3. The signal corresponding to the pen pressure point coordinates obtained by this scanning frequency, which is approximately 1/I000 of the wound MHZ, is Transmission over telephone lines with a limited bandwidth of 2 days is easily possible with current transmission technology.

In this specification, the state until the first pen pressure point coordinates are detected, that is, the scanning state in which the length of one side of the blackboard 10 is used as a unit, is defined as line scanning, and the first pen pressure point coordinates are detected. The latter state, that is, the scanning state in which only a predetermined range is scanned pixel by pixel is defined as partial scanning. Once the initial pen pressure point coordinates are detected and a predetermined scanning range is set, the pen pressure point can be tracked by performing partial scanning while moving the predetermined scanning range in the direction in which the coordinate signal changes. I can go.

Then, when the pen pressure point cannot be detected, the partial scanning returns to the line scanning and the entire blackboard 10 is scanned. In this case, when writing a broken line, etc., the writing pressure is temporarily removed from the blackboard 10. Therefore, if there is no pen pressure, you can reduce the number of line scans by checking that there is no pen pressure in that area even after scanning several frames of the last partial scan, and then moving to line scan. It is possible to detect minute ranges with high precision. Note that it takes 5.5 seconds to sequentially scan all pixels at 57.8 KH2, which is the same as partial scanning of the blackboard 10 with 490 x 581 pixels;
．． If line scanning is performed even at the frequency of HZ, the time to scan one frame will be as follows.

5.5 x carp ±20 skin S Therefore, the coordinates of the pen pressure point applied on the blackboard 10 can be detected within 2 plates S, and a practically sufficient performance can be obtained.

Next, the block diagram of FIG. 4 will be explained in detail.

Scanning of the blackboard 10 is performed according to the flowchart shown in FIG. 7, and when no pen pressure is applied to the blackboard 10', the microcomputer 16 causes the control logic 17 to turn on all the y-coordinate switch circuits 12 and scan the x-coordinate. A signal is supplied to turn on one switch among the switch circuits 11. For this reason, the control logic 17
decodes this signal and controls the scanning control circuit 13 to the state shown in FIG. 7B in accordance with the signal from the microcomputer 16. At this time, if no pen pressure is applied to the blackboard 10, no coordinate signal is output from the x-coordinate switch circuit 11, so the microcomputer 6 selects a new adjacent x-coordinate switch in place of the currently on x-coordinate switch. Control logic 1 sets the signal to turn on.
Send on 7. As a result, the control logic 17 turns on the adjacent switch of the x-coordinate switch circuit 11, which has been in the normal state, while keeping all the y-coordinate switch circuits on. Also at this time, x coordinate switch circuit 1
If no detection signal is output from the x-coordinate switch circuit 11, the microcomputer 16 sequentially transfers the ON switches of the x-coordinate switch circuit 11 to adjacent electrodes until a detection signal is obtained from the x-coordinate switch circuit 11. Repeat this action. Here, when pen pressure is applied to the blackboard 10, a detection signal is output from the x-coordinate switch circuit 11, so this signal is sent to the microcomputer via the A/○ converter 14 and the maximum pen pressure point detection circuit 15. 16th V
The state shown in FIG. 5 is reached.

Then, the microcomputer 16 fixes the x-coordinate switch circuit 11 to a switch that outputs a detection signal, and supplies the control logic 17 with a signal that turns on one switch among the y-coordinate switch circuits 12. Therefore, the control logic 17 decodes this signal and controls the scanning control circuit 13 in accordance with the signal from the microcomputer 6, resulting in the state shown in FIG. 7D. In this case, if no detection signal is obtained from the x-coordinate switch circuit 11, the microcomputer 16
In the same way as when scanning 1, the scanning points are sequentially transferred to adjacent switches. As the y-coordinate switch circuit 12 is sequentially scanned, the pen pressure point on the blackboard 10 is reached and a detection signal is output from the x-coordinate switch circuit 11, resulting in the state shown in FIG. 7E.

At this time, the scan control circuit 13 also applies to the memory circuits 19 and 20.
From x coordinate switch circuit 11 and y coordinate switch circuit 12
A control signal is supplied, and this control signal is the coordinates of the pen pressure point. For this reason, the microcomputer 1
6 supplies a signal to the control logic 17 to store the control signal as pen pressure point coordinates, so the control logic 17 decodes this signal and stores the control signal in the storage circuit control section 1.
Control 8. Therefore, storage circuits 19 and 20'
The one designated by the storage circuit control unit 18 stores the control signal. The two memory circuits 19 and 20 are provided because this electronic whiteboard system operates in real time, and even when coordinate signals are being stored, the microcomputer 16 is not performing processing for transmission. Is going. For this reason, two circuits are used so that while writing is being performed in one memory circuit, reading can be performed in the other. When the storage of the control signal as a coordinate signal is completed, the microcomputer 16 sets a predetermined range frame for partial scanning based on the location where the detection signal is generated, and controls the scanning of the x-coordinate switch circuit 11 and the y-coordinate switch circuit 12. The process starts and the state shown in FIG. 7F is reached.

Therefore, the pen pressure point on the blackboard 10 can be scanned in detail, and this 0 coordinate data is sent to the A/D converter 14 and the maximum pen pressure point detection circuit 15.
The signal is supplied to the microcomputer 16 via. The microcomputer 16 sends the input data to the transmitter 2.
1 to the receiving unit 22. By the way, blackboard 10
Since the coordinates of the pen pressure point applied generally change over time, it is necessary to constantly track this pen pressure point and move the range in which the frame is set as necessary.

Therefore, when the frame is scanned, if the coordinates of the pen pressure point detected first are different from those one frame before, a new frame is set again based on the new pen pressure point coordinates. In this way, as shown in FIG. 8, the frame moves from A to 8 to C to D along with the movement of the pen pressure point, making it possible to track the pen pressure. In this case, each time a new pen pressure point coordinate was detected within the scanning range, the frame was moved based on the new pen pressure point coordinate, but if the limit point of the frame was scanned, the pen pressure point coordinate It may be moved when there is no pen pressure point, or it may be moved in a direction estimated by the vector of pen pressure point coordinates.

Further, as described above, after the coordinates of the pen pressure point are no longer detected within the frame, by performing useless scanning for several frames, it is possible to accurately detect a minute range. The frame is set based on the pen pressure point coordinates, and in the present invention, the frame is set based on the coordinates corresponding to the maximum pen pressure point among the pen pressure point coordinates.

This means that when pressure is applied to the blackboard 101,
1.Since the elastic conductor sheet used has elasticity,
Even if the tip of chalk or the like that comes into contact with the blackboard 10 is sufficiently smaller than the resolution range, pen pressure is also applied to the area around the contact area between the chalk and the blackboard 10. For this reason, the setting range of the frame changes depending on how the pen pressure point is selected, so to prevent this, the frame is set based on the maximum pen pressure point. Furthermore, if all pen pressure point coordinates are transmitted to the receiving side, the lines on the display screen will become thicker, and a large amount of information must be sent.

For this reason, the present invention uses the pen pressure point coordinates of the maximum pen pressure point, but it is also possible to use other pen pressure points with a predetermined pen pressure or higher as the pen pressure point coordinates within a range that does not interfere with display. For example, the degree of redundancy increases, so there is an advantage that coordinate loss due to noise is less likely to occur. This maximum writing pressure point detection is performed, for example, with a configuration as shown in FIG.

In the figure, 24 is an input terminal, which is connected to the x-coordinate switch circuit 11 of FIG. and input terminal 24
The detection signal supplied to the analog comparator 25 is input to one input terminal of the analog comparator 25. Since the other input terminal of this analog comparator 25 is supplied with a voltage that determines the threshold level of pen pressure sensitivity, only when the value of the detection signal is greater than this threshold level, the analog comparator 25 2
5 supplies the output signal to the control end of an analog-to-digital converter (hereinafter referred to as A/D converter) 26. Since the input terminal 24 is also connected to the input terminal of the A/D converter 26, the A/D converter 26 converts the analog signal into a digital signal when the output signal of the analog comparator 25 is supplied, and converts the analog signal into a digital signal. Generates a completion pulse when the conversion is completed.

Then, this completion pulse and digital signal are supplied to the writing pressure maximum point detection circuit 15. The maximum pen pressure point detection circuit 15 is composed of a digital comparator, which temporarily holds the input digital signal, compares it with the next input digital signal, stores the larger value, and outputs it. It is something to do. By comparing the magnitudes of the coordinate signals in this way, it is possible to detect the maximum pen pressure point where the applied pen pressure is the maximum, so this output signal is sent from the output terminal 27 to the microcomputer 16 shown in FIG. do.

The analog comparator 25 is provided in order to reduce the processing time of the microcomputer 16 by not operating the A/D converter 26 when the writing pressure is below a predetermined value. In addition to this, there is a method called coordinate midpoint detection as a method for detecting the maximum pen pressure point.

This is because the surrounding points of the maximum pen pressure point are symmetrical with respect to the maximum pen pressure point, so the maximum and minimum coordinate values are determined separately in the vertical and horizontal directions. value)/2
The average coordinate value of is set as the point of maximum pen pressure. Furthermore, in the present invention, white characters or figures are displayed on the display screen based on the detected pen pressure point coordinates, so when erasing, black is set and the displayed white part is erased.

In this embodiment, the scanning frequency is 57. Although the frequency is set to 2, it is not limited to this frequency, and although the frame is set in a rectangular shape, other shapes such as a circle may also be used.

As explained above, the scanning method of the electronic whiteboard system according to the present invention sets a frame including the coordinates of the first pen pressure point in the area where the coordinates of the pen pressure point are detected, and sets the frame including the coordinates of the pen pressure point. Since the pen is moved in a direction estimated by a vector, it can be realized with a simple circuit configuration, and it has an excellent effect that the pen pressure can be tracked even if the pen pressure point moves quickly.

[Brief explanation of the drawing]

1 and 2 are a top view and a sectional view of a blackboard used in an embodiment of the present invention, FIG. 3 is a sectional view showing the structure of an elastic conductor sheet used in the blackboard, and FIG. A block diagram showing an embodiment of the invention, FIGS. 5 and 6 are circuit diagrams of the blackboard and the x-coordinate and y-coordinate switch circuits,
FIG. 7 is a flowchart, FIG. 8 is a front view of the blackboard showing the frame moving on the blackboard, and FIG. 9 is a block diagram showing the A/D converter and the maximum pen pressure point detection circuit. 1...Horizontal electrode group, 2...Vertical electrode group, 3
......Elastic conductor sheet, 4...Choke, 1
0...Satoita, 11...x coordinate switch circuit, 12...y coordinate switch circuit, 13...
...Scanning control circuit, 15... Maximum writing pressure point detection circuit, 16... Microcomputer, 19,2
0... Memory circuit. Figure 1 Figure 2 Figure 3 Figure 5 Figure 4 Figure 8 Figure 9 Figure 6 Figure 7

Claims (1)

[Claims] 1 After horizontally and vertically scanning an image transmission screen consisting of a group of electrodes arranged in a matrix to detect pen pressure point coordinates, and setting a frame in a predetermined range including the area where the first pen pressure point coordinates were detected, 1. A scanning method for an electronic whiteboard system that scans an area within the frame, wherein the frame is moved in a direction estimated by a vector of pen pressure point coordinates.