KR19980067261A - Door video phone signal method using multiple monitors and door video phone adopting the method - Google Patents

Abstract

In the door video phone signal method of connecting and using a plurality of monitors, one of each monitor is selected as a master, the other monitor is selected as a slave, and when the camera is not in use, the master monitor receives a first voltage. The master monitor applies a second voltage higher than the first voltage to the line if the call comes from the camera, and if the monitor responds to the call of the camera, The monitor applies the second voltage to the line, and the camera is a call signal. When the first voltage is applied to the line, the line voltage is temporarily varied, and the second voltage is applied to the line. If so, try temporarily suppressing the FM signal.

Description

Door video phone signal method using multiple monitors and door video phone adopting the method

The present invention relates to a door video phone, and more particularly to a door video phone that can be used by connecting a plurality of monitors in parallel.

The door video phone is a device for installing a camera in the front door of a house or building and installing a monitor in the room to check the visitor with a monitor in the room and then open the door. Conventionally, one monitor is connected to one camera and used in the door video phone.

However, depending on the type of residence, two or more households share a single gate. In this case, if only one monitor is used for one camera, only one household can see visitors, and two cameras can be used. There was a downside to the cost of installation. Therefore, it is conceivable to install and use two or more monitors in one camera in order to solve this disadvantage. However, even in this case, if the visitor who came to the other household and confirmed the visitor visited the other household, he or she should be able to inform the other household, or if the other household responded, the handset would be affected. There are many problems to be solved, such as not having to.

As a solution to this problem, a method of providing an interface unit for each monitor in each camera and connecting a plurality of monitors to the interface unit may be considered. However, when using this method, not only the cost of the camera increases but also the wiring has to be performed for each monitor, which is disadvantageous in that installation is inconvenient.

In addition, in the two-wire system that uses only two wires to connect the monitor and the camera, a single line needs to be used to supply audio signals, video signals, and power. There is.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is possible to connect two or more monitors to one camera in parallel using two wires, as well as to generate noise in sending call signals and response signals. It is an object of the present invention to provide a door video phone to be used by connecting a plurality of monitors.

1 is a schematic block diagram showing a connection between a monitor and a camera in a door video phone according to the present invention;

2 is a circuit diagram of a line interface unit of a camera of a door video phone according to the present invention;

3 is a circuit diagram of a signal receiving portion of a line interface unit of a monitor of a door video phone according to the present invention;

4 is a circuit diagram of a power supply and signal transmission part of a line interface unit of a monitor of a door video phone according to the present invention;

FIG. 5 is a waveform diagram of a line when transistor Q44 is turned on and off in one monitor to prevent operation of another monitor when a monitor responds to a call from a camera.

6 is a waveform diagram of an oscillator output when the transistor Q5 is turned on by a camera;

7 is a flow chart for explaining the operation of the control unit of the master monitor of the door video phone of the present invention;

8 is a flow chart for explaining the operation of the control unit of the slave monitor of the door video phone of the present invention.

Explanation of symbols on the main parts of the drawings

1 control unit 2 selector switch

3 Line Interface Unit (Monitor) 4 Power Supply Unit

5 Line Interface Unit (Camera) 6 FM Modulator

7 Amplifier 8 Band Pass Filter

9 Half-wave rectifier 10 Monitor 1

11 monitors 2 20 cameras

In order to achieve this object, the method of the present invention selects one of the monitors as the master and the other monitor as the slave, and when the camera is not in use, applies a first voltage to the line in the master monitor, and the camera When a call comes from the master monitor, a second voltage higher than the first voltage is applied to the line by the master monitor, and when one monitor responds to the call of the camera, the second monitor is connected to the second monitor. Voltage is applied to the line, and the camera is a call signal, and when the first voltage is applied to the line, the line voltage is temporarily changed, and when the second voltage is applied to the line, FM It is characterized by temporarily suppressing a signal.

In addition, the door video phone of the present invention employing such a method comprises: a selection switch for distinguishing a master and a slave from each of a plurality of monitors; A line voltage supply circuit capable of selectively supplying a first voltage and a second voltage higher than the first voltage; A first sensing circuit for sensing a temporary drop in line voltage; A second sensing circuit for sensing whether a line voltage is maintained at the first voltage or the second voltage; And a third sensing circuit for sensing whether a signal of a specific frequency exists in the line, wherein the camera comprises: a call switch; A first circuit for temporarily lowering the line voltage when the call switch is pressed while the line voltage is maintained at the first voltage; And a second circuit for suppressing the FM oscillation signal when the call switch is pressed while the line voltage is maintained at the second voltage. When the camera is in the standby state, the second circuit is selected from the plurality of monitors. The line voltage supply circuit of the monitor selected as the master by the switch supplies the first voltage to the line, and when the call signal comes from the camera, the line voltage supply circuit of the monitor selected as the master The second voltage is supplied, and the second voltage is supplied from the monitor which has responded when the monitor responds to the call of the camera.

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

1 is a schematic block diagram showing the connection between the monitor and the camera in the door video phone of the present invention, Figure 2 is a circuit diagram of the line interface unit of the camera of the door video phone of the present invention, Figure 3 is a view of the monitor of the door video phone of the present invention 4 is a circuit diagram of a signal receiving portion of the line interface unit. FIG. 4 is a circuit diagram of a power supply and signal transmission portion of the line interface unit of the monitor of the door video phone according to the present invention.

In the door video phone of the present invention, as shown in FIG. 1, two or more monitors 10 and 11 are connected to one camera 20 in parallel. The camera 20 includes a line interface unit 5, an FM modulator 6 for FM modulating the video signal photographed by the camera, and an amplifier 7 for amplifying the FM signal. Each of the monitors 10 and 11 includes a control unit 1, a slave master selection switch 2, a line interface unit 3, and a power supply unit 4.

First, at the time of shipment from the factory or at the installation in the field, the selection switch 2 of only one of the plurality of monitors 10 and 11 is used as the master, and the rest is placed as slaves. In the following description, it is assumed that the monitor 10 is selected as the master.

In the door video phone configured to supply power from the monitors 10 and 11 to the camera, power should be supplied from only one monitor. Therefore, in the present invention, only the monitor 10 selected as the master is configured to supply voltage to the line and other monitors do not supply voltage to the line. In addition, when the camera is not operating, there is no need to apply a voltage high enough to operate the camera, and only a voltage sufficient to receive a call signal from the camera. Hereinafter, the voltage supplied by the master monitor 10 at ordinary times, that is, when the camera 20 is not operating is referred to as a first voltage. At this time, when a voltage higher than the first voltage is applied to the line, the first voltage is supplied through the diode to prevent the reverse flow of current.

As described above, an operation when the call button is pressed in the camera 20 when the first voltage is supplied to the line will be described with reference to FIG. 2. 2 is a circuit diagram of the line interface unit 5 of the camera 20. In this figure, A is connected to a power supply circuit that receives the voltage supplied from the monitor and converts it into a voltage to be used in the camera, and a circuit for processing audio and image signals between the monitor and the camera, but is not related to the present invention. Is omitted. In addition, in the following figures, T1 and T2 represent terminals connected to the line. As described above, the first voltage is applied to the line under normal operation, that is, when the camera is not in operation. Therefore, the potential of the base of the transistor Q1 is increased at the emitter of the transistor Q1 by the zener diode ZD1 having a first voltage applied to A of FIG. 2 and having a zener potential equal to or higher than the first voltage. Since it is not lower than the first voltage, which is the potential of, the transistor Q1 is maintained in the turn-off state. Accordingly, the transistor Q2 also remains turned off, and since the first voltage is connected to the base of the transistor Q3 through the resistor R5, the transistor Q3 remains turned on and thus the transistor Q4. The collectors of R6 and R7 remain connected in parallel. At this time, when the visitor presses the call button SW1, the base of the transistor Q4 is connected to the ground through the resistor R9. Then, since the base voltage of the transistor Q4 is lower than that of the emitter, the transistor Q4 becomes conductive so that the line is connected to ground through a parallel combination of resistors R6 and R7. At this time, the resistance value by the parallel of the resistors R6 and R7 is set to a value low enough to drop the potential of the line. Therefore, the potential of the line drops instantaneously due to the resistance value obtained by the parallel combination of the resistors R6 and R7.

As described above, a method in which the monitor 10 or 11 detects this when the potential of the line falls by pressing the call button during the normal operation will be described with reference to FIG. 3. 3 is a data sensing circuit in the line interface section 3 of the monitors 10 and 11. In FIG. 3, B, C, and D are each connected to a control unit.

In FIG. 3, the filter 8 is configured to pass the video signal transmission modulation frequency in the camera. Since there is no video signal in the line when the camera is not operating normally, nothing appears at the output of the filter 8, so that a low value is applied to the base of the transistor Q22 so that the transistor Q22 remains turned off. have. In addition, since the first voltage is normally applied to T1, when Vcc is lower than or equal to the first voltage, the transistor Q23 maintains the turn-off state, and therefore, low is applied to D.

In this state, when the call button is pressed in the camera 20, the potential of the line temporarily drops as described above, and when the potential of the line temporarily drops, the potential of T1 in FIG. 3 also drops similarly. Then, the potential of the base of the transistor Q23 becomes lower than Vcc so that the transistor Q23 is turned on, so that high is applied to D so that the controller 1 knows that the call button is pressed in the camera 20. . Therefore, the monitors 10 and 11 can take an operation such as ringing chimes in response to a call signal from the camera.

When the call signal comes from the camera 20 as described above, the master monitor 10 applies a second voltage, which is higher than the first voltage, to the line. That is, the transistors Q43 and Q45 are turned on by applying high to E of FIG. 4, and the potential of the negative terminal of the comparator A30 is higher than the potential of the positive terminal by applying a low to F of FIG. 4. The transistor Q44 is turned on by bringing the output of the low) to VDD through the turned-on transistors Q43 and Q44 to form a second voltage.

Thus, the operation | movement when one monitor responds in the state which the 2nd voltage was applied to the line is demonstrated with reference to FIG. 3 and FIG. Since the second voltage is applied to the + terminal of the comparator A23 of FIG. 3 and the first voltage is applied to the − terminal of the second voltage applied to the line, the output C of the comparator A23 is applied. ) Becomes high so that the controller 1 knows that a second voltage is currently applied to the line. At this time, when taking a response operation such as picking up the handset or pressing the response button, the controller 1 applies a high to E of FIG. 4 to turn on the transistor Q43, and applies a low to F of FIG. Turn on). Of course, if the monitored monitor is the master monitor 10, the transistors Q43 and Q44 are already turned on, so this operation is unnecessary. On the other hand, if the responding monitor is the slave monitor 11, the second voltage is temporarily applied to the line from both monitors 10 and 11, but the problem is not caused because the period is short, as will be described later. Subsequently, the controller 1 temporarily turns off the transistor Q44 by temporarily applying high to F. Then, the second voltage applied through the transistor Q44 is momentarily blocked, and the potential drops instantaneously on the line as shown in FIG. 5 (a part). Will rise (part b).

As described above, a circuit for detecting the same when another waveform is displayed on the track as shown in FIG. 5 will be described. Usually, since the potential of the + terminal of the comparator A21 is higher than the potential of the-terminal, the output of the comparator A21 maintains Vdd, and this voltage is applied to the-terminal of the comparator A22. On the other hand, since the voltage of the line is applied to the + terminal of the comparator A22, the potential of the-terminal of the comparator A22 becomes higher than the potential of the + terminal, so that the output of the comparator A22 is low, and thus the transistor Q21. Is turned off, and high is transmitted to the control unit 1 through B. FIG. On the other hand, in the case where the waveform shown in Fig. 5 appears on the line, since the potential of the-terminal of the comparator A22 is still higher than the potential of the + terminal in the portion a, no change occurs in the potential of B, but the portion of the comparator ( A potential higher than the second voltage is applied to the + terminal of A22, the output of the comparator A22 becomes high, and the transistor Q21 is turned on. Therefore, the potential of B becomes ground, so that the low signal is transmitted to the controller 1. If a low signal is displayed on B, monitors other than the one that responded do not take action when the user picks up the handset or presses the answer button (it may cause a call to beep). Do not fall. In addition, if the slave monitor 11 responds to the call from the camera 10, the master monitor 10 applies a low to E of FIG. 4 to turn off the transistor Q43, thereby reducing the second voltage. To prevent it from being applied to the track. That is, from now on, the voltage is applied from the monitor which responded to the line.

Meanwhile, a case in which the call button is pressed again by the camera while the second voltage is applied to the line will be described with reference to FIG. 2. At this time, the second voltage is already applied to the camera and the video signal is loaded on the track, and the speaker of the camera is turned on. When the voltage of the line becomes the second voltage, a second voltage is applied to A of FIG. 2, and a Zener diode ZD1 having a Zener potential between the first voltage and the second voltage causes the transistor Q1 to have a second voltage. The base receives a lower voltage than the second voltage. Accordingly, the transistor Q1 is turned on so that the voltage obtained by dividing the second voltage by the resistors R3 and R4 is applied to the base of the transistor Q2. Accordingly, the transistor Q2 is also turned on so that the base of the transistor Q3 is grounded. Transistor Q3 is turned off. As a result, only the resistor R7 is connected to the collector of the transistor Q4 while the potential of the line is maintained at the second voltage. At this time, if the value of R7 is set high enough so as not to affect the potential of the line, even if the switch SW1 is pressed and the transistor Q4 is turned on, only the resistance R7 is connected to the line so that there is no change in the potential of the line. Therefore, noise and the like do not occur. On the other hand, when the transistor Q4 is turned on by pressing the switch SW1, the potential of the collector of the transistor Q4 is raised to the second voltage which is the potential of the line in the ground state, and this instantaneous potential rise is made through the capacitor C1. Applied to the base of transistor Q5. The transistor Q5 is then turned on so that the line from the FM modulator 6 to the amplifier 7 is pulled down to ground. Therefore, the video signal applied to the line is largely suppressed as shown in part c of FIG.

In this case, the operation of the monitors 10 and 11 will be described with reference to FIG. 3. While the second voltage is applied to the line, the line carries the FM video signal from the camera. The FM video signal is converted into a direct current by the rectifier circuit 9 via the filter 8 of FIG. 3 tuned to its modulation frequency and applied to the base of the transistor Q22. Transistor Q22 is then turned on to pull the potential at the base of transistor Q23 to ground, thus turning transistor Q23 to apply Vcc to D. Therefore, when D changes from low to high, the controller 1 may know that the call signal is received from the camera 20 and take an operation such as ringing a chime. That is, although the speaker of the camera 20 is on while the second voltage is being applied to the line, the camera does not change by changing the DC potential of the line to notify the call of the camera but by suppressing the FM signal from the camera 20. By notifying the call from 20, it is possible to inform the monitors 10 and 11 of the call signal from the camera 20 without generating noise.

In order to perform the same operation as described above, the operation procedure of the control unit 1 of the master and slave monitors 10 and 11 will be described with reference to FIGS. 7 and 8. 7 is a flowchart for explaining the operation of the control unit 1 of the master monitor 10 of the door video phone of the present invention, Figure 8 is a control unit 1 of the slave monitor 11 of the door video phone of the present invention. This is a flowchart for explaining the operation in.

First, the control part 1 of the master monitor 10 monitors whether a call from a camera normally comes as shown in FIG. 7 (step 100). As described above, the master monitor 10 applies the first voltage to the line, and the operation of the call monitoring circuit at this time is as described above. When the call comes from the camera 20, the master monitor 10 applies a second voltage to the line, which is a voltage higher than the first voltage (step 101). The monitor then monitors whether the master monitor 10 responds (step 102) or the other monitor 11 responds (step 106).

In the case where the master monitor 10 responds (YES in step 102), as described above, the master monitor 10 is notified by temporarily applying a low to F of FIG. 4 (step 103). Then, a call is made between the camera 20 and the master monitor 10. The master monitor 10 continuously checks whether or not the call is terminated (step 104) and when the call ends (i.e., hang up the handset or presses the end call button on the master monitor 10), the process goes to step 105 and the E of FIG. Breaking the second voltage by applying a low. As described above, in the master monitor 10, since the first voltage is always connected to the line through the diode, if the second voltage is not applied to the line, the first voltage is automatically applied. Disconnecting the second voltage returns to the initial state (step 100).

On the other hand, if another monitor responds in step 106, the process goes to step 107 and the second power source is turned off. At this time, a call is being made between the other monitor and the camera 20. The master monitor 10 continuously checks whether the call is terminated (step 108), and when the call is terminated (that is, the other monitor 11 ends the call and tracks it. When the second voltage applied to the line is cut off and the first voltage is finally applied to the line), the master monitor 10 detects that C in FIG. 3 goes low and proceeds to the initial step 100.

Next, the operation of the control unit 1 of the slave monitor 11 will be described with reference to FIG. 8. The control unit 1 of the slave monitor 11 continues to monitor whether a call from the camera 20 normally comes (step 200). As described above, the master monitor 10 applies the first voltage to the line at this time, and the operation of the call monitoring circuit at this time is as described above. When a call comes from the camera 20, a second voltage from the master monitor 10 is applied to the track, where the slave monitor 11 responds (step 201) or at another monitor. Monitor for a response (step 205).

If it responds to itself (YES in step 201), a second voltage is applied to the line by applying a high to E of FIG. 4 as described above, and temporarily low to F of FIG. Inform them that they have responded by applying (step 202). Then, a call is made between the camera 20 and the slave monitor 11. The responding monitor 11 continues to check whether the call is terminated (step 203) and when the call ends (i.e., hang up the handset or press the end button), go to step 204 and apply a low to E of FIG. Break the voltage of 2. As described above, in the master monitor 10, since the first voltage is always connected to the line through the diode, if the second voltage is not applied to the line, the first voltage is automatically applied. Disconnecting the second voltage returns to the initial state (step 200).

On the other hand, if the other monitor has responded in step 205, go to step 206 and continue checking whether the call is terminated between the other monitor and the camera 20 (step 206). When the second voltage applied to the line is cut off and the first voltage is applied to the line), the slave monitor 11 detects that C in FIG. 3 goes low and proceeds to the initial step 200. do.

In the above description, the case of two monitors has been described with reference to FIG. 1, but the number of monitors is not limited. However, the number of master monitors should be set to one, and by doing so, the signal method of the door video phone of the present invention and the door video phone employing the method can be realized.

In addition, although the circuit which can implement this invention was shown and demonstrated in the detailed description of this invention, this invention is not limited only to this circuit. That is, the present invention can be realized by various changes or modifications to the configuration of the circuit and the elements used, and when such changes or modifications are obvious to those skilled in the art, It belongs to a category.

As described above, according to the present invention, not only can two or more monitors be connected to one camera in parallel, but also can be connected by using only two wires, so that the installation is simple and easy to maintain, and the signal transmission between the camera and the monitor is performed. It is possible to obtain effects such as no noise generated by the.

Claims (2)

In the door video phone having a camera and a plurality of monitors, Each of the plurality of monitors includes: a selection switch for distinguishing a master from a slave; A line voltage supply circuit capable of selectively supplying a first voltage and a second voltage higher than the first voltage; A first sensing circuit for sensing a temporary drop in line voltage; A second sensing circuit for sensing whether a line voltage is maintained at the first voltage or the second voltage; And a third sensing circuit for detecting whether a signal having a specific frequency exists in the line. The camera comprises a call switch; A first circuit for temporarily lowering the line voltage when the call switch is pressed while the line voltage is maintained at the first voltage; And a second circuit for suppressing the FM oscillation signal when the call switch is pressed while the line voltage is maintained at the second voltage. When the camera is in the standby state, the line voltage supply circuit of the monitor selected as the master by the selection switch among the plurality of monitors supplies the first voltage to the line, and when the call signal from the camera is supplied to the master. Supplying the second voltage to the line in the line voltage supply circuit of the selected monitor, and supplying the second voltage from the monitor that responded when the monitor responds to the call of the camera. Door video phone using a plurality of monitors, characterized in that for connecting. In the signal method of the door video phone to connect a plurality of monitors, Select one of each monitor as master and the other monitor as slave, and if the camera is not in use, apply the first voltage to the line in the master monitor, and if the call comes from the camera, A second voltage higher than the first voltage is applied to the line, and if any monitor responds to the call of the camera, the second voltage is applied to the line from the monitor that made the response; The camera is a call signal that temporarily changes the line voltage when the first voltage is applied to the line, and temporarily suppresses the FM signal when the second voltage is applied to the line. Door video phone signal method for connecting and using a plurality of monitors characterized in that.