JPH02186784A - Picture drawing ordering device - Google Patents

Abstract

PURPOSE:To easily transmit coordinates data by providing communication equipment with plural channels, and transmitting the coordinates data by using all the channels while a remote party side does not perform transmission, and changing a part of the channels into receiving use when the remote party side starts the transmission. CONSTITUTION:A coordinate change detecting part 4 discriminates whether a mouse 1 moved or not according to the change of its coordinates, and when it detects the change of the coordinates, it sends a coordinates change detection signal to a MODEM change-over control part 5, and the control part 5 operates as follows. Now, when the CD signal of a receiving MODEM A 13 is turned OFF during reception by the receiving MODEM A 13 and the transmission by a transmitting MODEM B 14, at the same time as a switch 19 is opened, an RST signal is outputted to the transmitting MODEM A 12, and the transmission is performed by both the channels A, B. Then, when the remote party side starts the transmission, a part of the channels is changed into the receiving use. Thus, the coordinates data can be easily demodulated.

Description

[Detailed description of the invention] [Industrial application field] The present invention includes a drawing input device and a display device.

The present invention relates to a drawing meeting device that allows both a sending side and a receiving side to have a meeting using drawings while talking over a transmission path such as a telephone line.

[Conventional technology]

Traditionally, as a remote gold and silver system using general telephone lines,
As described in Japanese Unexamined Patent Publication No. 62-144455, when a drawn image is input from a drawing input device normally in a call mode, there is a device that shifts to a drawing transmission mode and transmits drawing data. This system returns to call mode when you stop inputting drawn images, but markers and other items remain on the screen (2) so that you can have a meeting in call mode while looking at them.

[1llK@ the invention aims to solve] However, even if you try to send coordinate data by moving your own coordinate input device while the other party is transmitting, you will not be able to send the coordinate data until the other party finishes transmitting. The problem was that I couldn't do it.

Therefore, one possible solution to this problem is to configure two channels, one for transmitting and one for receiving, but since each channel is dedicated to transmitting or receiving, it is wasted when one channel is not used. It ends up. In particular, in meetings and the like, it is unlikely that both parties will send drawing information at the same time, resulting in poor transmission efficiency.

An object of the present invention is to provide a drawing meeting device that solves the problems of the prior art and allows smooth meetings.

[Means to solve the problem]

The above object is a coordinate input means for inputting coordinate data from the drawing input device in a drawing meeting device that has a drawing input device and a display device and conducts meetings by transmitting and receiving drawing data bidirectionally using a telephone line etc. a display means for displaying the position C2 index of the display device indicated by the coordinate data; a communication means having a plurality of channels for transmitting and receiving coordinate data with the other party; communication state identification means for identifying whether the state is reception start or reception end; This is achieved by providing communication switching means for transmitting and receiving respectively.

Preferably, a coordinate data switching means is provided which alternately distributes and transmits the coordinate data to each of the channels at predetermined time intervals.

Further, the above object has a drawing input device and a display device,
In a drawing meeting device that bidirectionally transmits and receives drawing data using a telephone line or the like to conduct a meeting, a coordinate input means inputs coordinate data from a drawing input device, and an index is displayed on a display device at a position indicated by the coordinate data. a communication means having two channels for transmitting and receiving coordinate data to and from the other party; each of the two channels starts transmitting,
communication state identification means for identifying whether the state is transmission end, reception start, or reception end; and depending on the identification result of the communication state identification means, both of the two channels are set for transmission or reception, or This is achieved by providing communication switching means, one for transmission and one for reception.

Preferably, coordinate data switching means is provided that alternately distributes and transmits the coordinate data to the two channels at predetermined time intervals.

[Effect]

The drawing meeting device of the present invention displays a figure or a cursor by the display means at the position on the display device indicated by the coordinate data input by the coordinate input means, and at the same time transmits the coordinate data by the communication means to the other party. The same information is displayed on the display device, and if you start transmission when neither transmitting nor receiving, if the communication status identification means identifies that the other party is not transmitting, the communication switching means All channels of the communication means are switched to transmission and coordinate data is transmitted, and conversely, when the communication state identification means identifies a transmission start signal from the other party when neither transmission nor reception is being performed, the communication switching means switches the coordinate data to the communication means. The coordinate data is received by switching all channels for reception.

In addition, if you want to start transmission while the other party is transmitting, the communication switching means switches some of all channels of the communication means for transmission to send and receive coordinate data, and conversely, all channels When the correspondence identifying means identifies a transmission start signal from the other party while transmitting coordinate data, the communication switching means switches some channels of all channels of the communication means for reception, and transmits and receives the coordinate data. do.

Also, when transmission is completed while transmission and reception are being performed on some channels, the communication switching means switches the channel that was transmitting to reception and receives on all channels, and vice versa. When the reception is completed while the reception is being performed on some channels at a time, the communication switching means switches the channel on which the reception was being performed for transmission, and transmits on all channels.

Further, when transmitting coordinate data, the coordinate data switching means alternately distributes and transmits the coordinate data to some channels of the communication means at predetermined time intervals.

In this way, when the other party is not transmitting, a large amount of information can be transmitted on all channels, and when both parties are transmitting, coordinate data can be transmitted in full duplex on some channels. Moreover, since the coordinate data to be transmitted is alternately distributed to each channel at predetermined intervals, even when switching from some channels to all channels, or from all channels to some channels, special transmission data conversion processing is required. Coordinate data can be transmitted without the need for

〔Example〕

Hereinafter, a first embodiment of the drawing meeting apparatus of the present invention will be described with reference to FIGS. 1, 2, and 3.

FIG. 1 is a block diagram showing the configuration of a drawing meeting device that can transmit drawing data while talking over a single telephone line.

Regarding the first factor, the drawing meeting device of this embodiment has A, B
It has two channels, 1 and 101 are mouse, 2 and 102 are mouse input interfaces, 3 and 10
3 is a transmission data conversion unit, 4 and 104 are coordinate change detection units, 5 and 105 are modem switching control units, 7 and 107 are transmission buffers (B), 8 and 108 are transmission buffers (B), and 11 and 111 are tone sending units. 12 and 112 are transmitting modems (A), 13 and 113 are receiving modems (A), and 14 and 114 are transmitting modems (B)
, 15 and 115 are receiving modems (B), 16 and 1
16 is a tone detection section, 17 and 117 are frequency multiplexing sections, 18 and 118 are telephones, 19 and 119 are switches, 20 and 120 are switches, 21 and 121
is a reception buffer (A), 22 and 122 are reception buffers (B), 23 and 123 are reception data converters, and 24
and 124 are display control units, and 25 and 125 are displays.

FIG. 2 is a flowchart for explaining the operation of the modem switching control section 5 of the drawing meeting apparatus shown in FIG. 1, and FIG. 3 is an auxiliary diagram for explaining the operation of the drawing meeting apparatus shown in FIG.

First, the operation of the main parts will be explained. However, when the other party is not transmitting, it is necessary to transmit not only on one channel but on both channels.

The mouse input interface 2 converts data from the mouse 1 into coordinate data and outputs it to the transmission data converter 3, coordinate change detector 4, and display controller 24. The transmission data conversion unit 5 converts the coordinate data into transmission data, adds an identification signal to the beginning of the transmission data indicating one coordinate, and alternately converts the coordinate data into the transmission buffer (A) 7 and the transmission buffer (B) at predetermined time intervals. Output to 8. At this time, in order to identify which transmission buffer has earlier data, four types of identification symbols are added in order from the earliest in terms of time: 0), Naka), Guu, Ni). The coordinate change detection unit 4 is
It is determined whether the mouse 1 has moved or not based on a change in its coordinates. When a change in coordinates is detected, a coordinate change detection signal is output to the modem switching control section 5. As shown in the flowchart of FIG. 2, the modem switching control section 5 operates as follows depending on the state of the detection signal from the coordinate change detection section 4 and the carrier detection signal (CD signal) from each modem.

When the coordinate change detection signal arrives, the receiving modem (A) 1
When both the CD signals of the receiving modem (B) 3 and the receiving modem (B) 15 are off, the tone sending unit 111 sends out the tone generation start signal for a certain period of time, and then sends a transmission permission signal (RTS signal) to the sending modem (B) 12. It is output to both modem (B) 14 and transmitted on both channels A and 8.

When the tone detection section 16 detects a tone signal from the other party while the coordinate change detection signal from the coordinate change detection section 4 is not coming, that is, it is not being transmitted, the switches 19 and 20 are closed, and the signals A and 8 are not transmitted. Receive on channel.

When the coordinate change detection signal arrives, if the CD signals of the receiving modem unit) 13 and the receiving modem (B) 15 are both on, that is, if the CD signals are being received on both channels, the tone sending unit 11 After outputting the tone generation start signal for a certain period of time, the RTS signal is output only to the transmitting modem (B) 14, and the switch 19 is opened to receive it on the A channel and transmit it on the B channel.

When data is being transmitted on both channels A and 8, when the tone detection unit 16 detects a tone signal from the other party,
At the same time as stopping the R'l'S signal to the transmitting modem (B) 14, the switch 20 is closed and the received data from the receiving modem (B) 15 is transferred to the receiving buffer (B) 22.
channel and receive on the B channel.

Transmit with transmitting modem (A) 12 and receiving modem (B) 15
If the coordinate change detection signal from the coordinate change detection unit 4 stops coming, the R to the transmitting modem (A) 12
At the same time as stopping the 'l'S signal, the switch 19 is closed to transfer the received data from the receiving modem (A) i5 to the receiving buffer (A) 21 and receive it on both channels A and 8.

When the receiving modem (A) 13 is receiving and the transmitting modem (B) 14 is transmitting, if the CD signal of the receiving modem (A) i3 is turned off, opening the switch 19 simultaneously switches the transmitting modem l, A ) 12 and transmits it on both channels A and 8.

The received data converter 23 looks at the identification signals added to the beginning of the received data from the receive buffer (A) 21 and the receive buffer (B) 22, and discriminates which data is earlier in time. For example, identification signals (B) are added to the received data of the reception buffer (A) 21 and (B) to the reception data of the reception buffer (B) 22. If so, it is determined that the received data in the receive buffer (A) 21 is two times earlier. If the received data in the receive buffer 21 (A) and the received data in the receive buffer 7 (B) 22)
If the identification signal is added, the reception buffer (
B) It is determined that the received data of No. 22 is earlier in time.

The frequency multiplexer 17 transmits the voice of the telephone 18, the tone transmitter 11, the transmitting modem (A) 12, and the transmitting modem (B) 14.
The signals are frequency-divided, multiplexed, and output to the telephone line.

This will be explained below using an actual communication example. However, it is assumed that the mice 1 and 101 on the A and B sides in FIG. 1 are both stationary.

First, when the mouse 1 on the instep side is moved, it is converted into coordinate data by the mouse input interface 2 and output to the transmission data conversion section 3, the coordinate change detection section 4, and the display control section 24. The transmission data converter 3 converts the coordinate data in order from the earliest in time (a) l←).

(c), ni) and 4 types of identification signals are added in turn, and the transmission buffer (A) 7 and the transmission buffer (B) are alternately added.
) Output to 8. The coordinate change detection section 4 detects that the coordinate data from the mouse input interface 2 has changed, and outputs a coordinate change detection signal to the modem switching control section 5. On the other hand, the display control unit 24 displays the index at the position on the display 25 indicated by the coordinate data obtained from the mouse input interface 2.

The modem switching control section 5 receives the coordinate change detection signal from the coordinate change detection section 4, and since the CD signals of the reception modem (A) 13 and the reception modem (B) 15 are both off, After outputting the tone generation signal for a certain period of time, the transmitting modem prisoner 12 and the transmitting modem (B) 1
41:R? Outputs S signal.

Upon receiving this, the transmitting modem (A) 12 and the transmitting modem 14 output a transmission permission signal (c'rs signal) to the transmitting buffer (A) 7 and transmitting buffer a3) 8, respectively, and do not receive the transmitted data. frequency multiplexer 17
After frequency multiplexing with the voice of telephone 1B, it is output to the telephone line. This is a drawing of FIG. 3(a) when transmitting on both channels, where the circle mark goes into the sending buffer (false) 7, and the Δ mark goes into the sending buffer (B) 8.

On the other hand, on the second side, the tone detection section 116 detects the tone signal from the first side and outputs a detection signal to the modem switching control section 105. The modem switching control unit 10 that received this
5, since the coordinate change detection signal from the coordinate change detection section 104 is not detected, the switches 119 and 120 are closed.
Receiving modem (A) 113 and receiving modem (B) 1
The data received by 15 is transferred to the reception buffer (A) 12
1 and output to the reception buffer (B) 122. The reception data conversion unit 123 sorts the data from the reception buffer (A) 121 and the reception buffer (B) 122 in order from oldest to oldest based on the identification signal, and outputs the rearranged data as coordinate data to the display control unit 124. Display 12
Displayed on 5.

In this state, when the mouse 101 on the second side is moved, the data is converted into coordinate data by the mouse input interface 7 ace 102 and output to the transmission data conversion section 103, the coordinate change detection section 104, and the display control section 124. Transmission data converter 10
5 is the coordinate data in order from the earliest in time @),
It is output to the transmission buffer (A) 107 and the transmission buffer (B) 108 alternately while adding four types of identification signals (1=), (c), ni). Coordinate change detection unit 104
detects that the coordinate data from the mouse input interface 102 has changed, and outputs a coordinate change detection signal to the modem switching control section 105. - side, display control section 12
4 displays an index at the position on the display 125 indicated by the coordinate data obtained from the mouse input interface 102.

The modem switching control unit 105 that receives the coordinate change detection signal from the coordinate change detection means 104 switches the receiving modem (A) 1
Since the CD signals of 15 and receiving modem (B) 115 are both turned on upon receiving the signal from the instep side, after outputting the tone generation signal to tone sending section 111 for a certain period of time, the CD signal of receiving modem (B) 115 is outputs an RTS signal. The transmitting modem (B) 114 that received this transmits CT'
The J signal is outputted to the transmission buffer (A) 1071m, and the transmitted data is received and modulated, frequency-multiplexed with the voice of the telephone 118 by the frequency multiplexing section 117, and then outputted to the telephone line.

Furthermore, on the A side, the tone signal from the B side is detected by the tone detection section 16, and the detection signal is output to the modem switching control section 5. Upon receiving this, the modem switching control section 5 receives the coordinate change detection signal from the coordinate change detection section 4, and since both the transmission modem (A) 12 and the transmission modem (B) 14 are currently transmitting, the modem switching control section 5 receives the coordinate change detection signal from the coordinate change detection section 4. ) R to 14 only
Stop the TS signal, close the switch 20, and connect the receiving modem (
Transfer the received data from B) 15 to the reception buffer (B) 22. The reception data converter 23 converts the reception buffer (A
) 21 is empty and there is no identification signal, so the data only in the reception buffer (B) 22 is converted into coordinate data and output to the display control section 24, and the index is displayed on the display 25. This is the transmission buffer (
A) Coordinate data of only 7 is transmitted and displayed on both displays 25 and 125.

Here, the party B stops the mouse 101 and the coordinate change detection unit 1
04 notifies the modem switching control unit 105 that the coordinate change has stopped, the modem switching control unit 105 stops sending the RTS signal to the transmitting modem (B) 114 to stop transmission, and closes the switch 120. On the instep side, the receiving modem (B
) 15 is turned off, the modem switching control unit 5 outputs the RTS signal to the transmitting modem (B) 14 again, and at the same time opens the switch 20 to perform transmission on both channels A and B. is the receiving modem (B) 11
Since the CD signal from 5 is turned on, the modem switching control section 105 closes the switch 120, the received data enters the reception buffer (B) 122, and the received data conversion section 1
After passing through 23, it enters the display control section 124 and is displayed on the display 125. The state shown in FIG. 3(a) is again achieved.

In this way, in a drawing meeting device that has two channels, the coordinate data to be transmitted is distributed to each channel alternately at predetermined time intervals, and when one drawing meeting device is transmitting, both channels are used. Transmit high-resolution data, and when both drawing meeting devices are transmitting, one channel is divided into transmission and reception, and the thinned out data is transmitted, and both channels are sent to one channel, or one channel Even if the coordinate data is switched from ζ to both channels, the coordinate data can be transmitted to the other party without loss. Also, when both parties are not communicating (2. There is a possibility that tone signals are sent out at the same time, in this case, the tone frequency is determined by the calling side and the responding side, and one side sends out the tone. This can be solved by starting transmission on both channels if there is no tone from the other party for a predetermined period of time, and transmitting and receiving on one channel at a time if a tone is received from the other party within the predetermined period.

Next, a second embodiment (two embodiments) of the drawing meeting apparatus of the present invention will be described with reference to FIGS. 4 and 5.

FIG. 4 is a block diagram showing the configuration of a drawing meeting device capable of transmitting drawing data while talking over a single telephone line.

In Figure 4, the same symbols as in Figure 1 indicate the same names,
60 and 130 are attenuators, and 51 and January are error detection units.

FIG. 5 is a flowchart illustrating the operation of the modem switching control section 5 of the drawing meeting apparatus shown in FIG. 4, and the basic operation is the same as in the first embodiment.

This will be explained below using an actual communication example. However, it is assumed that the mice 1 and 101 on the A side and the B side in Fig. 4 are both stationary, the attenuators 30 and 130 have approximately the same amount of attenuation as the telephone line, and both are on the same channel. It is assumed that the words are arranged so that they will be incorrect if they are sent simultaneously.

First, when the mouse 1 on the instep side is moved, coordinate data is converted by the mouse input interface 2 and output to the transmission data conversion section 3, the coordinate change detection section 4, and the display control section 24. The transmission data converter 3 converts the coordinate data in order of time (a) and (b) from earliest to earliest.

(c), ni) and 4 food identification signals are added in turn (2 transmission buffers (A) 7 and 2 transmission buffers (A) 7 and 4 food identification signals).
B) Output to 8. The coordinate change detection section 4 detects that the coordinate data from the mouse input interface 2 has changed, and outputs a coordinate change detection signal to the modem switching control section 5. On the other hand, the display control unit 24 displays the index at the position on the display 25 indicated by the coordinate data obtained from the mouse input interface 2.

The modem switching control unit 5 receives the coordinate change detection signal from the coordinate change detection unit 4, and since the CD signals of the receiving modem (A) 13 and the receiving modem (B) 15 are both off, ) 12 and transmitting modem (B) 1
al: Outputs an RTS signal. The transmitting modem (A) 12 and transmitting modem (B) 14 that have received this output the CTS signal to the transmitting buffer body) 7 and the transmitting buffer (B) 8, respectively, receive and receive the transmitted data, modulate it, and frequency The multiplexer 17 frequency-multiplexes the audio with the voice of the telephone 18 and then outputs it to the telephone line.

On the other hand, on the second side, when the CD signals of the receiving modem (A) 115 and the receiving modem (B) 115 are both turned on, the modem switching control section 105 receives the coordinate change detection signal from the coordinate change detection section 104. Since there is no signal, close switches 119 and 120 and connect the receiving modem (
A) The data received by the receiving modem (B) 115 is output to the receiving buffer (A) 121 and the receiving buffer (B) 122. The reception data conversion unit 123 rearranges the data from the reception buffer (A) 121 and the reception buffer CB) 122 from oldest to oldest based on the identification signal, and outputs it to the display control unit 124 as seated image data. and displays it on the display 125.

In this state, when the mouse 101 on the user's side is moved, the data is converted into seated image data by the mouse input interface 102 and output to the transmission data converter 103, seat change detector 104, and display control fls124. The transmission data conversion unit 106 sends the coordinate data to the transmission buffer (A) 107 in order from the earliest in time (A), (B), (-→, NI) while adding identification signals of four woodcutter types. and output to the transmission buffer (B) 10B. Coordinate change detection section 10
4 detects that the coordinate data from the mouse input interface 102 has changed, and outputs a coordinate change detection signal to the modem switching control section 105.

On the other hand, the display control unit 124 displays an index at a position on the display 125 indicated by the seated image data obtained from the mouse input interface 102.

The modem switching control unit 105 that receives the coordinate change detection means from the coordinate change detection means 104 switches the receiving modem (A) 1
Since the CD signals of 13 and receiving modem (B) 115 are both turned on in response to the signal from the instep side, the R'1''S signal is output only to transmitting modem (g) 114.

The transmitting modem (B) 114 that receives the signal outputs the CTS signal to the transmitting buffer (A) 107, receives and modulates the transmitted data, and after frequency multiplexing it with the voice of the telephone 118 in the frequency multiplexing section 117, transmits the CTS signal to the transmitting buffer (A) 107. Output to line.

In this state, the transmission modem (B) 14 on the Party A side and the transmission modem (B) 114 on the Party B side are both in a state of transmission failure, so the transmission data of the transmission modem (B) 14 on the Party A side is monitored. The received modem (B) 15 generates an error and outputs an error detection signal to the error detection section 31. The error detection section 31 detects the amount of errors, and outputs a detection signal to the modem switching control section 5 when the number of errors is greater than a predetermined set value. Upon receiving this, the modem switching control section 5 switches the transmitting modem (B) to the transmitting modem (B).
Stop the RTS signal to 14 to stop transmission, switch 2
0 is closed and the received data from the transmitting modem) 15 is transferred to the receiving buffer 22. Since the data in the reception buffer 21 is empty and there is no identification signal, the reception data conversion unit 25 converts the data in the reception buffer 22 only into coordinate data, outputs it to the display control unit 24, and displays the index on the display 25. .

Here, the party B stops the mouse 101 and the coordinate change detection unit 1
04 notifies the modem switching control section 105 that the coordinate change has stopped, the modem switching control section 105 stops sending the R'L'S signal to the transmitting modem (B) 114 to stop transmission, and closes the switch 120. On the Party A side, since the CD signal from the receiving modem (13) 15 is turned off, the modem switching control section 5 outputs the RTS signal to the transmitting modem (13) 14 again, and simultaneously opens the switch 20 and switches both A and B. The receiving modem (B) on the Party B side that transmits on the channel
Since the CD signal from 115 is turned on, the modem switching control section 105 closes the switch 120, and the received data enters the reception buffer (B) 122, passes through the reception data conversion section 123, and then enters the display control section 124. displayed on the display 125.

In this way, in a drawing meeting device that has two channels, the coordinate data to be transmitted is divided into two channels alternately at predetermined intervals, and when one drawing meeting device is transmitting, both channels are used. High-resolution data is transmitted, and when both drawing meeting devices are transmitting, one channel is divided into transmission and reception and thinned data is transmitted, and from both channels to one channel,
Alternatively, even if the coordinate data is switched from one channel to both channels, the coordinate data can be transmitted to the other party without loss.

Although each of the above embodiments uses a communication means having two channels, the number of channels is not limited to two, and may have two or more channels.

〔Effect of the invention〕

As explained above, the present invention has a drawing input device and a display device on both the sending side and the receiving side, and has multiple channels in a drawing meeting device configured to conduct a meeting while talking over a single telephone line. A communication means is provided so that when the other party is not transmitting, coordinate data is transmitted using all channels, and when the other party starts transmitting, some channels are switched to reception. Furthermore, by distributing drawing data to each channel alternately in time, even when switching from all channels to some channels, or from negative channels to all channels, there is no need for special data conversion. This has the advantage that coordinate data can be easily demodulated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a drawing meeting device according to the first embodiment of the present invention, which can transmit drawing data while talking over a single telephone line, and FIG. 2 shows the drawing meeting shown in FIG. A flowchart for explaining the operation of the modem switching control section of the device, FIG. 5 is an auxiliary diagram for explaining the drawing meeting device of FIG. 1, and FIG. 4 is a flow chart for explaining the operation of the modem switching control section of the device. FIG. 5 is a block diagram showing the configuration of a drawing meeting device according to a second embodiment of the present invention that can transmit data.
This figure is a flowchart for explaining the operation of the modem switching control section of the drawing meeting apparatus of FIG. 4. 1.101...Mouse. 2.102...Mouse input interface, 5.10
5... Transmission data conversion section, 4.104... Coordinate change detection section, 5.105... Modem switching control section, 7.107.
...Transmission buffer (A), 8.108... Transmission buffer (B). 11.111... Tone sending unit, 12.112... Transmitting modem prisoner, 15.115... Receiving modem (A), i'4, 11
4...Transmission modem (B). 15.115...Receiving modem (B), 16.116.
...Tone detection section. 17.117... Frequency multiplexing section. 18.118...Telephone. 19.20,119,120...Switch-21,1
21...Reception buffer (A). 22.1 23.1 24.1 25.1 30.1 31.1 22...Reception buffer (J3), 23...Reception data conversion section 24...Display control section, 25...Display. 30... Attenuator, 31... Error detection section. No. 111￥1 2nd Ca (α) β Risen Yanner Kenshikai Time (b) One Channel Nenom” 9th Kanji No.

Claims (1)

[Scope of Claims] 1. In a drawing meeting device that has a drawing input device and a display device and uses a transmission line such as a telephone line to send and receive drawing data in both directions for a meeting, A coordinate input means for inputting data, a display means for displaying an index at the position of the display device indicated by the coordinate data, a communication means having a plurality of channels for transmitting and receiving coordinate data with the other party, and each of the plurality of channels Communication state identification means for identifying whether the state is transmission start, transmission end, reception start, or reception end, and all of the plurality of channels are used for transmission or reception depending on the identification result of the communication state identification means. 1. A drawing meeting device, characterized in that it is provided with a communication switching means that makes one part for transmission and one part for reception. 2. The drawing meeting apparatus according to claim 1, further comprising coordinate data switching means for alternately allocating and transmitting the seated image data to the partial channels at predetermined time intervals. 3. The communication means having two channels for transmitting and receiving coordinate data to and from the other party, and the communication for identifying whether each of the two channels is in a state of transmission start, transmission end, reception start, or reception end. A state identification means and the communication switching means are provided for making both of the two channels for transmission or reception, or for making one each for transmission and reception, depending on the identification result of the communication state identification means. The drawing meeting apparatus according to claim 1, characterized in that: 4. The drawing meeting apparatus according to claim 3, further comprising coordinate data switching means for alternately distributing and transmitting coordinate data to the two channels at predetermined time intervals.