KR200253020Y1 - Monitor selective distributer and education system for the same - Google Patents

Abstract

The monitor selection dispenser of the present invention is to send the monitor screen output signal from the teacher's computer to the student monitor when the computer is used for education, but the monitor screen belonging to each student is under the control of the teacher. A first connector (CN1) for receiving a monitor output signal of; A second connector CN2 for receiving a monitor output signal from a computer system other than the manager side; At least one transmission side connector (CN3 or CN4) for transmitting the monitor output signal from the manager side to the connection end; A fifth connector CN5 for outputting a monitor output signal to the monitor of the distributor; A 'lock' signal generator 600 generating a 'lock' signal for outputting the monitor output signal of the manager to each monitor; A signal switching unit (RY1, 200) for connecting the monitor output signal of the first connector to the fifth connector according to the 'lock' signal; And a control unit (300, 400) for detecting the 'lock' signal to drive the signal switching unit, wherein the 'lock' signal is input through a specific pin of the first connector and detected by a corresponding distributor. The 'lock' signal is characterized in that it is configured to be transmitted to the distributor of the next stage through a particular pin of the at least one transmission side connector (CN3 or CN4).

Description

MONITOR SELECTIVE DISTRIBUTER AND EDUCATION SYSTEM FOR THE SAME}

The present invention relates to a router of a computer monitor, and more particularly, to a monitor selection dispenser having a 'lock' operation board for the administrator to selectively control the screen of the entire monitor and an education system using the same.

To display at least two computer outputs on one monitor, divide the monitor screen into two or four screens so that the output of each computer is displayed in each divided area, or output from each computer at different times. There is a way to selectively accept and output to the monitor. The former is by a monitor router and the latter is by a monitor select distributor.

The present invention relates to a monitor selection dispenser and an education system using the same. According to the dispenser according to the present invention, an administrator such as a teacher and a non-administrator such as a student each have their own monitor on one computer output or one computer output. And when it is arranged to be selectively accessible to the computer output of each non-administrator, it is easy to connect and install, and the administrator can control the screen displayed on the non-administrator's monitor by 'LOCK' operation, one type Multiple monitors and computer outputs can be connected to each other with the same adapter, and a monitor selection divider that enables the construction of a system that does not require a separate power supply to each distributor can be constructed with a single power supply and training using the same. It's about the system.

That is, the first object of the present invention is to provide a monitor screen output signal from the teacher computer to the student monitor when the education through the computer, the monitor screen belonging to each student can be selectively used under the teacher's control It provides a monitor divider. In other words, if the teacher hangs' lock 'during the education, only the screen from the teacher's computer body is output on the students' monitor. Therefore, students will not be able to use their computers without permission, thus enhancing the educational effect. On the other hand, when the teacher releases the 'lock' operation, the student can control his monitor selection divider to alternately print the teacher screen and his screen for viewing.

The second object of the present invention is that when connecting several monitors to the teacher's computer with RGB cable, it is possible to connect in various ways such as tree structure or ring method without using constellation topology. It provides a monitor selection distributor that is easy to connect.

It is a third object of the present invention to provide a monitor selection dispenser capable of covering both the teacher-side dispenser and the student-side dispenser with one type of the same dispenser when connecting several monitors.

It is a fourth object of the present invention to provide a monitor selection divider that can be distributed without providing a separate power source to each distributor and that there is almost no change in image quality even when multiple monitors are connected in multiple stages.

Further objects or effects of the present invention will become more apparent from the following detailed description of the invention described with reference to the accompanying drawings.

1 is an external view of a monitor selection dispenser according to the present invention.

Figure 2 is a connection diagram of each distributor in the education system using a monitor selection distributor according to the present invention.

3 is an overall circuit diagram of a portion excluding a control unit and a display unit of the monitor selection distributor according to the present invention;

4 is a circuit diagram of a control unit and a display unit of the monitor selection distributor according to the present invention.

<Description of the symbols for the main parts of the drawings>

100: amplification unit 200: first selection unit

300: relay drive unit 400: 'LOCK' state detection unit

500: 'LOCK' signal amplification unit 600: internal control unit

700: display unit

Monitor selection distributor according to an aspect of the present invention for achieving the above object, the first connector (CN1) for receiving a monitor output signal from the manager side; A second connector CN2 for receiving a monitor output signal from a computer system other than the manager side; At least one transmission side connector (CN3 or CN4) for transmitting the monitor output signal from the manager side to the connection end; A fifth connector CN5 for outputting a monitor output signal to the monitor of the distributor; A 'lock' signal generator 600 generating a 'lock' signal for outputting the monitor output signal of the manager to each monitor; A signal switching unit (RY1, 200) for connecting the monitor output signal of the first connector to the fifth connector according to the 'lock' signal; And a control unit (300, 400) for detecting the 'lock' signal to drive the signal switching unit, wherein the 'lock' signal is input through a specific pin of the first connector and detected by a corresponding distributor. The 'lock' signal is characterized in that it is configured to be transmitted to the distributor of the next stage through a particular pin of the at least one transmission side connector (CN3 or CN4).

Preferably, the signal switching unit is configured to convert one pair of RGB signals of an RGB signal of the first connector CN1 and an RGB signal of the second connector CN2 according to a control signal of the controller. Relay RY1 for connecting to CN5 and any one of a horizontal / vertical signal of the first connector CN1 and a horizontal / vertical signal of the second connector CN2 according to the detection of the lock state of the controller. And a horizontal / vertical signal selector 200 for connecting a pair of horizontal / vertical signals to the fifth connector CN5. More preferably, the controller may include the lock signal. A 'lock' state detection unit 400 for detecting 'high' and 'low' states, and a relay driver 300 for generating a driving signal for driving the relay RY1 according to the 'lock' state. It is characterized by including.

Also preferably, the apparatus further includes a 'lock' signal amplifier 500 for transmitting the 'lock' signal to the next stage without attenuation, or a first specific pin of the first connector CN1 is connected to a reference power terminal. And at the same time a first specific pin of said at least one transmission side connector CN3 or CN4 is also connected to said reference power supply terminal.

On the other hand, the education system using a monitor selection dispenser according to another aspect of the present invention, the monitor selection dispenser is connected to the computer main body of the teacher computer system, the second connector is not connected anywhere, the at least one transmission side The connector CN3 or CN4 is connected to the first connector CN1 of the distributor of the first connection terminal of the student side via a cable, and the signal switching units RY1 and 200 are connected to the fifth connector only by the first connector CN1. (CN5) is fixedly installed so as to connect the monitor selection distributor to the computer body of the student side computer system, the second connector is the computer body 22, 22 ', 32, 32 '), when the' lock 'signal is in the' LOCK 'state, the first connector CN1 is connected to the fifth connector CN5, and the' lock 'signal is' UNLOCK ' In the case of the state, the second connector CN2 is set and installed to be connected to the fifth connector CN5, and at least one transmission side connector CN3 or CN4 of the distributor at the first connection end of the student side. Is configured to be connected via a cable to the first connector (CN1) of the distributor of the subsequent connection end of the student side.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an external view of a monitor selection dispenser according to the present invention, Figure 2 is a connection diagram of each dispenser in the education system using the monitor selection dispenser according to the present invention, Figure 3 is a control unit and display of the monitor selection dispenser according to the present invention 4 is a circuit diagram of the control unit and the display unit of the monitor selection distributor according to the present invention.

First, as shown in Figure 1, the monitor selection distributor 10 according to the present invention, five connectors (for example HD15PIN) (CN1-CN5) is out, one selector switch 11 from the outside Can be connected.

As shown in FIG. 2, the teacher-side distributor 10 first connects the teacher-side PC main body 12 (specifically, VGA) via a cable to the first connector CN1. To the third connector CN3 and the fourth connector CN4, respectively, via the cable to the distributors 20 and 20 'of the first student row and the distributors 30 and 30' of the second student row. ) Is connected. More specifically, the first connector CN1 of the first student side distributor 20 of the first student side row is connected to the third connector CN3 of the teacher side distributor 10, and the first student of the first student side row 10. The first connector CN1 of the second student side distributor 20 ′ of the first student side row is connected to the third connector CN3 of the side distributor 20. Similarly, the first connector CN1 of the first student side divider 30 of the second student side row is connected to the fourth connector CN4 of the teacher side divider 10, and the first student side divider of the second student side row 10 is connected. The first connector CN1 of the second student side distributor 30 'of the second student side row is connected to the third connector CN3 of 30. In the case of a daisy chain connection other than the tree structure, the second student side connection is not necessary.

On the other hand, a monitor is connected to the fifth connector CN5 of the teacher-side distributor 10, and when the remote control is desired, the teacher-side selection switch 11 is connected to the distributor 10. The connection thereof will be described later with reference to FIG. In the case of the teacher-side distributor, since it is the first connection terminal, other devices do not need to be connected to the second connector CN2. Therefore, in the case of the teacher-side distributor, the first connector CN1 functions as an input mode, and the third to fifth connectors CN3-CN5 function as an output mode.

Next, the connection of the first student side distributor 20 of the first student side row will be described. As described above, the first connector of the first student side distributor 20 is connected to the third or fourth connector of the teacher side distributor. Input from the teacher-side computer 12 and distributor 10 is received, and the second connector CN2 is connected to its own computer body 22 (specifically a VGA card), and the third connector is connected to the next stage. It is connected to the student side divider of 20 'is also to pass the output signal of the teacher side computer 12 and the divider 10. The fifth connector CN5 is also connected to its own monitor 23, and if the remote control is also desired, the student side selector switch 21 is connected to the distributor 20. The fourth connector CN4 may or may not be connected as necessary. In other words, if a continuous tree structure is needed, another student side divider may be connected.

On the other hand, in the case of the second student side divider 20 'of the first student side row, the first student side divider 20 is connected to the first connector, and the corresponding student side computer 2' is connected to the second connector. A student side divider (not shown) of the next stage is connected to the three connectors, and a monitor 23 'of the corresponding student side is connected to the fifth connector, and a selection switch 21' may be connected as necessary.

The other student side splitters 30 and 30 'are also the same as the connection of the student side splitters 20 and 20', and thus further detailed description thereof will be omitted.

3 and 4, the internal circuitry of the distributor is now described. In FIG. 3, the positions of the connectors are shown in the order of the first and second connectors CN1 and CN2 from the top of the left, and the third to fifth connectors CN3-CN5 from the top of the right.

For each connector, the HD15PIN connector is taken as an example, in which pins 1 to 3 are connected to RGB signal lines, and pins 13 and 14 are used for horizontal and vertical signal lines. Pins 5-8 and 10 are grounded. Pins 4 and 12 are used for special purposes in this design. In other words, pin 4 is used as a channel for transmitting 'lock' signal, and pin 12 is used for transmitting Vcc power.

First, the case of the teacher-side distributor 10 will be described. At the first installation, the switches SW1 (see Fig. 4) and SW2 are fixed in the direction shown in the dotted line, and the relay RY1 is also indicated by the dotted line in the first connector. CN1 is set in a state where it is connected to the fifth connector CN5.

Therefore, in the case of the first connector CN1. Pins 4 and 12 are also grounded and floating, which does nothing.

The RGB signal lines of pins 1 to 3 of the first connector CN1 are connected to pins 1 to 3 of the third and fourth connectors CN3 and CN4 via the amplifier 100, and at the same time, the relay RY1. Pin 1 is connected to pins 1 to 3 of the fifth connector CN5. More specifically, the RGB signal lines of pins 1 to 3 of the first connector CN1 are connected to the non-inverting input side of the amplifiers Q3 to Q5, respectively, and the outputs of the amplifiers are again connected to the third through connection resistors R10 to R12. Input of the relay RY1 to pins 1 to 3 of the connector CN3 and to pins 1 to 3 of the fourth connector CN4 through the connection resistors R13 to R15 and through the connection resistors R16 to R18. It is connected to one side of the pin. The remaining resistors R1 through R9 are the basic resistance elements for the amplifier. The output terminal of the relay RY1 is connected to pins 1 to 3 of the fifth connector CN5, and the other input of the relay comes from pins 1 to 3 of the second connector CN2.

Horizontal and vertical signal lines 13 and 14 of the first connector CN1 are connected to pins 13 and 14 of the third and fourth connectors CN3 and CN4, and the horizontal / vertical signal selector 200 is simultaneously connected. Via pins 13 and 14 of the fifth connector CN5. More specifically, horizontal and vertical signal lines 13 and 14 of the first connector CN1 are connected to pins 13 and 14 of the third connector CN3 through buffers Q12 and Q13 and through buffers Q15 and Q16. Pins 13 and 14 of the fourth connector CN4 and pins 13 and 14 of the fifth connector CN5 through the buffers Q6 and Q7 of the horizontal / vertical signal selector 100. The other input of pins 13 and 14 of the fifth connector CN5 also comes from pins 13 and 14 of the second connector. That is, the horizontal and vertical signal lines of pins 13 and 14 of the second connector are connected to pins 13 and 14 of the fifth connector CN5 through buffers Q8 and Q9 of the horizontal / vertical signal selector 100.

The relay driver 300 has a collector side connected to Vcc and an emitter side connected to the control point d of the relay RY1, and the base side connected to the 'locked' state sensing unit 400 (c) through the resistor R20. It is configured. Again, the 'lock' signal detection unit 400, the sub-control terminal is connected to the switch SW2A and SW2C (a), the input side to the switch SW2B (e) and the output side (b) through the inverter Q10 relay drive (c) ) Is connected. At this time, the output signal of the buffer Q11 (the input signal of the inverter Q10) (b) is connected to the control points of the buffers Q6 and Q7 of the horizontal / vertical signal selector 200, and the output signal (c) of the inverter Q10 is horizontal / vertical. The control points of the buffers Q8 and Q9 of the signal selector 200 are connected. A resistor R19 connected at one side to Vcc is connected to the emitter of the switching transistor Q1, and resistors R21 to R23 connected at one side are connected to a control point, an output terminal, and an input terminal of the buffer Q11, respectively.

The driving signal d of the relay RY1 is applied by the relay driving unit 300. The generation of the control signal c of the relay driving unit 300 and the selection unit 200 will be described in detail below.

First, the 'lock' state detection unit 400 includes a buffer Q11. In the case of the teacher-side distributor, all of the second switches SW2A-SW2D are blocked (dotted lines), and thus, the buffer Q11 is operated. The lock 'signal a is low and the buffer Q11 is in the connected state. However, the input and output signals b of the buffer remain unchanged in the low state, and the control signal c through the inverter is in the high state. Accordingly, a high voltage is applied to the base terminal of the first switching transistor Q1 of the relay driver 300 through the resistor R20, and eventually, Vcc is continuously applied to the relay driving signal c, and the relay RY1 is applied. Still transmits the RGB signal of the first connector CN1 to the fifth connector CN5 for monitor connection as it is initially fixed, and the first selector 200 also continues to operate the buffers Q6 and Q7. The horizontal / vertical signal of the first connector CN1 is transmitted to the fifth connector CN5 for monitor connection. Therefore, only the output of the teacher-side computer 12 is displayed on the teacher's monitor 13.

On the other hand, the 'lock' signal generator 600 of Figure 4, the clock terminal of the D flip-flop (DF / F) through the inverters Q16 and Q17, the first switch (SW1), one side is connected to Vcc acts as a latch Is entered. The first output terminal Q of the D flip-flop is connected to the switch SW2B (see FIG. 1) through the terminal NET, and the first output ( ) Is connected to the input terminal D to switch the control signal from low to high or from high to low every time the teacher presses the first switch. On the other hand, it may be connected to the connector JC1 for the selection switch 11 in parallel with the switch. Therefore, the same effect can be achieved by pressing the remote selection switch instead of the first switch. A parallel circuit of a resistor R26 and a capacitor C1 having one side grounded is connected to the output terminal of the switch SW1.

On the other hand, when describing the 'lock' signal amplification unit 500, the output connection (NET) (e) of the 'lock' signal generating unit 600 of the 'lock' signal amplification unit 500 through the switch SW2B Connected to the base of the second switching transistor Q2, the collector of the second switching transistor Q2 is connected to Vcc and the emitter is connected to the fourth connector CN3 and the fourth connector CN4 through the resistor R24. It is connected to the number pin f.

Therefore, the teacher may generate the 'lock' signal through the first switch SW1 or the selection switch 11, in which case the output signal e of the 'lock' signal generator 600 is 'high'. ', The first switching transistor Q2 of the' lock 'signal amplifying unit 500 is turned on to apply the Vcc signal to pins 4 of the third and fourth connectors CN3 and CN4. When the output signal e is 'low', the signal values applied to pins 4 of the third and fourth connectors CN3 and CN4 are also in a low state, which is 'unlocked' as described below.

Finally, referring to FIG. 3 and FIG. 4, the input of the relay driver 300 (that is, the output of the 'locked' state detecting unit 400) (c) is connected to the terminal LED1 of FIG. 4. It is connected to the first light emitting diode D1, and displays whether or not the current relay driving unit is operating by chewing gum.

On the other hand, the input terminal (a) of the 'locked' state detection unit 400 is connected through the connection connector LED2 and the connection terminal for the selection switch is directly connected to the second light emitting diode (D2), which is thus 'locked' The status will be displayed. Output terminals of the first and second light emitting diodes D1 and D2 are grounded through a resistor R25.

Pin 12 of the third connector CN3 of FIG. 3 is connected to Vcc through the switch JP1, which transmits the Vcc voltage to pin 12 of the first connector CN1 of the student side divider of the next stage, and switches Since Vcc power is applied to the entire distributor through SW2D, in principle, the monitor selection distributor according to the present invention can operate without a power supply, but if the distributor itself receives Vcc power through a separate adapter (not shown) The switch JP1 may be opened.

Now, the student side dispenser will be described again with reference to FIGS. 3 and 4. The student-side distributor is also the same as the teacher-side distributor, except that the first switches SW2A to SW2D are set in reverse at the first installation, so that all of the second switches in FIG. 3 are connected in the solid line direction.

Therefore, as described above, the 12th pin of the first connector (which is connected via the cable to the 12th pin of the teacher side divider 10 or the third or fourth connectors CN3 and CN4 of the student side divider of the front end) is connected through a cable. Vcc power is supplied through the switch SW2D to supply the Vcc of the student side distributor 20, the student side distributor is operated by no power.

Similarly, to pin 4 of the first connector (which is connected via cable to pin 4 of the teacher-side distributor 10 or the third or fourth connector CN3, CN4 of the student-side distributor at the front end). An applied 'high' or 'low' 'LOCK' signal is applied to the control point a of the inverter Q11 of the 'lock' state detection unit 400 through the switch SW2A. At the same time, the 'lock' signal is applied to the 'lock' signal amplifying unit 500 through the switch SW2C.

First, a state in which the 'lock' signal is 'high' will be described. In this case, it means 'lock' is applied when reducing, and in this case, since the buffer Q11 is in a blocking state, the student himself or herself controls the control signal through the first switch SW1 or the selection switch JC1 of FIG. This does not affect the relay RY1 or the horizontal / vertical signal selector 200 because it is blocked in the buffer Q11. That is, the current state (signal b is low, signal c is high, and relay RY1 connection is dotted) continues, and the monitor signal from the teacher computer 12 is continuously displayed on the monitor. At the same time, the 'high' signal as the 'lock' signal a is applied to the base terminal of the second switching transistor Q2 of the 'lock' signal amplifying unit through the switch SW2C, and the third connector CN3 as described above. Pin 4 of the fourth connector CN4 transmits the lock signal of the Vcc voltage to the divider of the next stage.

On the contrary, when the 'lock' signal applied to the student-side distributor is 'low', it means 'unlocked', and in this case, the driving signal of the buffer Q11 is also 'low', so that the buffer (Q11) is operated, the switch SW2B of the input signal terminal of the buffer is also in the 'on' state through the connection terminal 'NET' and the monitor selection signal generator ('lock' signal generator 600 of FIG. Signal (e)). That is, the student can control the input signal of the buffer Q11 from 'high' to 'low' or vice versa through the first switch SW1 or the remote switch JC1 in the distributor. .

When the control signal e is switched from low to high, the output of the buffer Q11 is also switched from low to high, so the input signal c of the relay driver 300, which is the output of the inverter Q10, becomes low. In response, the drive signal d to the relay RY1 is switched and in response, the relay switches the contact point from the input side of the amplifying unit 100 of the RGB signal of the first connector CN1 corresponding to the monitor output signal of the teacher. It switches to the input side of the RGB signal of the 2nd connector CN2 which receives the monitor output signal from a computer. In addition, the horizontal / vertical signal selector 200 also operates Q8 and Q9 instead of the buffers Q6 and Q7 so that pins 14 and 15 of the second connector CN2 are no. 14 of the fifth connector CN5 for monitor connection. And pin 15.

At the same time, since the low signal a is applied to the base of the second switching transistor Q2 of the 'lock' signal amplifying unit 500, the switch Q2 is turned off and the 'low' to the third and fourth connectors. 'Signal' is applied to the next stage student divider, 'low' signal is continuously applied. That is, the 'lock' is not caught, so students can output the monitor output signal of the teacher to their own monitor by selecting the monitor output signal selection unit (refer to (600) of FIG. 4) or monitor the own computer. You can also output the output signal to your monitor.

Table 1 shows the state of each major element of the teacher-side divider, and Table 2 shows the state of each major element of the student-side divider.

Signal a Q11 Signal b (c) Q1 H / V selection part Signal d relay CN5 connection Signal e CN3 Pin 4 L action L (H) off Q6, Q7 L dotted line CN1 H H L action L (H) off Q6, Q7 L dotted line CN1 L L

Signal a Q11 Signal b (c) Q1 H / V selection part Signal d relay CN5 connection Signal e CN3 Pin 4 H Inaction L (H) off Q6, Q7 L dotted line CN1 - H L action L (H) off Q6, Q7 L dotted line CN1 L L L action H (L) On Q8, Q9 H Switch Switch H L

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, the present invention is not limited thereto, and various modifications are possible within a range easily conceived by those skilled in the art. Therefore, the limitation of the present invention should be limited only by the following utility model registration claims.

As described above, according to the monitor selection dispenser according to the present invention, the monitor screen belonging to each student when the education through the computer can be placed under the control of the teacher so that students can not use their own computer without permission It is possible to enhance the educational effect, and when connecting several monitors, it is possible to connect in various ways such as tree structure or ring method. It is possible to cover both the side divider or the student side divider with the same type of divider, and it is possible to operate about 5 to 10 dispensers without providing a separate power supply to each dispenser, and multiple monitors There is almost no change in image quality even when connected to.

Claims (6)

In the monitor selection dispenser, A first connector CN1 that receives a monitor output signal from the manager side; A second connector CN2 for receiving a monitor output signal from a computer system other than the manager side; At least one transmission side connector (CN3 or CN4) for transmitting the monitor output signal from the manager side to the connection end; A fifth connector CN5 for outputting a monitor output signal to the monitor of the distributor; A 'lock' signal generator 600 generating a 'lock' signal for outputting the monitor output signal of the manager to each monitor; A signal switching unit (RY1, 200) for connecting the monitor output signal of the first connector to the fifth connector according to the 'lock' signal; And It includes a control unit (300, 400) for detecting the 'lock' signal to drive the signal switching unit, The 'lock' signal is input through a specific pin of the first connector and is detected at a corresponding distributor, and the 'lock' signal is connected to a next stage through a specific pin of the at least one transmission side connector CN3 or CN4. A monitor selection dispenser, configured to be sent to the dispenser. The method of claim 1, The signal switching unit connects a pair of RGB signals of an RGB signal of the first connector CN1 and an RGB signal of the second connector CN2 to the fifth connector CN5 according to a control signal of the controller. One of the horizontal and vertical signals of the first connector CN1 and the horizontal and vertical signals of the second connector CN2 according to the detection of the relay RY1 and the lock state of the controller. And a horizontal / vertical signal selector (200) for connecting a vertical / vertical signal to the fifth connector (CN5). The method of claim 2, The controller may include a 'lock' state detection unit 400 for detecting 'high' and 'low' states of the 'lock' signal, and driving to drive the relay RY1 according to the 'lock' state. And a relay driver (300) for emitting a signal. The method according to any one of claims 1 to 3, And a 'lock' signal amplifying unit (500) for transmitting the 'lock' signal to the next stage without attenuation. The method according to any one of claims 1 to 3, A first specific pin of the first connector CN1 is connected to a reference power supply terminal, and at the same time, a first specific pin of the at least one transmission-side connector CN3 or CN4 is also connected to the reference power supply terminal; Monitor Selection Divider. A monitor selection distributor according to any one of claims 1 to 3 is connected to the computer body of the teacher's computer system, wherein the second connector is not connected anywhere, and the at least one transmission side connector (CN3 or CN4). ) Is connected to the first connector (CN1) of the distributor of the first connection terminal on the student side via a cable, the signal switching unit (RY1, 200) is connected only to the fifth connector (CN5) the first connector (CN1) Fixedly installed, A monitor selection distributor according to any one of claims 1 to 3 is connected to a computer body of the student computer system, and the second connector is connected to the computer body 22, 22 ', of the student computer system. 32, 32 ', and when the' lock 'signal is in the' LOCK 'state, the first connector CN1 is connected to the fifth connector CN5, and the' lock 'signal Is set to be able to be connected to the second connector (CN5) when the 'unlock' state, at least one of the distributor of the first connection end of the student side And the transmission side connector (CN3 or CN4) is connected to the first connector (CN1) of the distributor at the subsequent connection end of the student side via a cable.