JP3944139B2 - TV door phone device - Google Patents

Description

  The present invention relates to a television door phone device that allows a householder to confirm visitors by images at a plurality of locations indoors and allows telephone calls between the householder and the visitor.

  In general, as shown in FIG. 8, this type of TV door phone apparatus includes a door phone slave device 10 with a camera disposed at a front door of a house, a door phone master device 20 with a television disposed indoors, and a door phone child. A cable 40 that connects the machine 10 and the doorphone master unit 20, a doorphone sub-master unit 30 with a TV that is arranged in a separate room from the doorphone master unit 20, and the doorphone master unit 20 and the doorphone sub-master unit 30. It is comprised with the cable 50 (for example, refer patent document 1). Here, the door phone slave unit 10 is connected to the connection terminal 219 of the door phone master unit 20 via the cable 40 connected to the connection terminal 112. Further, the connection terminal 312 of the doorphone sub-master device 30 that receives the video signal from the doorphone master device 20 is connected to the connection terminal 220 of the doorphone master device 20 by the cable 50, and the visitor's video is displayed in the doorphone slave device. 10 is sent from the doorphone master unit 20 to the doorphone sub-master unit 30.

  As shown in FIG. 9, the doorphone slave unit 10 includes a camera unit 101 having a television camera that images a visitor, a video signal modulation circuit 102 that modulates a video signal from the camera unit 101, and a doorphone master unit 20 or doorphone. A receiving speaker 103 and a transmitting microphone 105 for making a call with a householder via the sub-master unit 30, a receiving amplifier 104 for driving the receiving speaker 103, and a transmitting for amplifying the sound from the transmitting microphone 105 The amplifier 106, the two-wire / four-wire conversion circuit 107 for handling two signals of the transmission signal and the reception signal by a pair of lines, and the DC power supplied from the doorphone master unit 20 via the cable 40 are stabilized. A power supply circuit 10 that supplies power to the camera unit 101, the video signal modulation circuit 102, the reception amplifier 104, the transmission amplifier 106, and the two-wire / four-wire conversion circuit 107 A push button 109 for calling a householder, a multiplexing circuit 110 for multiplexing video and audio signals into two lines, a terminal 112 for connecting to the door phone master unit 20, and a connection line (cable 40). And a diode bridge 111 for making the connection non-polar.

  On the other hand, as shown in FIG. 10, the doorphone master unit 20 includes a transformer that performs balanced-unbalanced conversion, a band-pass filter, and the like, a video signal receiving circuit 203 that receives a video signal from the doorphone slave unit 10, and a video A video signal demodulating circuit 201 that demodulates the video signal received by the signal receiving circuit 203, a television 202 that displays video based on the video signal demodulated by the video signal demodulating circuit 201, and a video signal that is sent to the doorphone sub-master device 30. Is composed of a buffer amplifier 204, a transformer for performing unbalanced-balance conversion for transmitting a good video signal to the doorphone sub-master device 30, a band-pass filter, and the like, and sends the video signal to the doorphone sub-master device 30. Video signal transmission circuit 205, handset 209 for talking with a visitor on the side of handset 10, handset 2 A receiver amplifier 207 that drives the receiver 209a of the receiver 9, a transmitter amplifier 208 that amplifies the sound from the microphone 209b of the handset 209, and two wires 4 for handling two signals of the transmitter signal and the receiver signal on a pair of lines. Line conversion circuit 206, call switching switch 211 for switching connection of the communication path between doorphone slave unit 10 and doorphone sub-master unit 30, and a call button press detection circuit for recognizing whether or not the call has been called from doorphone slave unit 10 212, and controls the internal circuit of the doorphone master unit 20 such as on / off control of the television 202 based on the signal obtained from the call button press detection circuit 212, and sends a control signal to the doorphone sub-master unit 30. The CPU 213 for sending and the control signal sent to the doorphone sub-master device 30 and the control signal sent from the doorphone sub-master device 30 are modulated. The control signal modulation / demodulation circuit 214 for demodulating the signal, the DC power superimposing circuit 216 for the slave unit for supplying power by superimposing the power to the door phone slave unit 10 on two lines, and the power source for the door phone sub-master unit 30 DC power superimposing circuit 218 for the sub master unit for superimposing power on two lines and supplying the power source and the internal power source of door phone master unit 20 from the commercial power source (AC 100V) connected via the power cord and DC power source for the slave unit The power circuit 217 that supplies power to the superimposing circuit 216 and the sub-master DC power superimposing circuit 218, and the audio signal and the video signal from the doorphone slave unit 10 are separated from the two lines and the doorphone master unit 20 (or the doorphone sub-parent) 2, and the audio signal and control signal from the doorphone sub-master unit 30 are multiplexed with each other. A doorphone sub-master unit multiplexing circuit 215 for multiplexing video signals, audio signals, and control signals from the doorphone master unit 20 to the doorphone sub-master unit 30 on two lines and the doorphone slave unit 10 are separated from the line. And a terminal 220 for connecting to the door phone sub-master device 30.

  Further, as shown in FIG. 11, the intercom sub-master unit 30 includes a transformer that performs balanced-unbalance conversion, a bandpass filter, and the like, and a video signal receiving circuit 301 that receives a video signal transmitted from the intercom master unit 20. A video signal demodulating circuit 302 that demodulates the video signal received by the video signal receiving circuit 301, a television 303 that displays video based on the video signal demodulated by the video signal demodulating circuit 302, and the doorphone slave unit 10 side. A handset 308 for talking to a visitor or another householder on the side of the doorphone master unit 20, a receiver amplifier 306 for driving the receiver 308a of the handset 308, and a transmitter amplifier 307 for amplifying the sound from the microphone 308b of the handset 308; A two-wire four-wire conversion circuit 305 for handling two signals of a transmission signal and a reception signal with a pair of lines, and a door phone Control of the internal circuit of the doorphone sub-master device 30 such as on / off control of the television 303 based on detection of the carrier signal of the video signal from the device 20 or detection of the synchronization signal or detection of the control signal, and the doorphone parent A CPU 310 for sending a control signal to the machine 20, a control signal modulation / demodulation circuit 309 for modulating a control signal sent to the doorphone master 20 and demodulating a control signal sent from the doorphone master 20, and a doorphone parent The power supply circuit 311 that stabilizes the DC voltage supplied from the device 20 and supplies power to the internal circuit of the doorphone sub-master device 30, and the audio signal, video signal, and control signal from the doorphone master device 20 are separated from the two lines. A multiplexing circuit 304 for multiplexing audio signals and control signals from the doorphone sub-master unit 30 to the doorphone master unit 20 in two lines, Ahon and a terminal 312 for connection to the base unit 20.

Next, an example of bus wiring in a dwelling unit of this type of TV door phone apparatus will be described with reference to FIGS. The doorphone slave unit 10 attached to the front door of the dwelling unit A is connected to the doorphone master unit 20 installed in one room in the dwelling unit A via the cable 40. In addition, the wiring from the doorphone master 20 to the plurality of doorphone sub-masters 30 installed in the same floor in the dwelling unit A or other rooms on the upper floor is connected by a bus 50 with one bus wiring system. The end of the wiring is terminated by a termination device 60 composed of a resistor or the like. The termination device 60 is configured by a resistor having a resistance value equal to the characteristic impedance of the cable 50, for example.
Japanese Patent Application Laid-Open No. 7-15724

  By the way, in the conventional TV door phone apparatus, since there is only one indoor bus wiring, when the number of door phone sub-master devices 30 is increased and wiring is performed in a room or a higher floor on the same floor, wiring is performed in the dwelling unit A. It was necessary to draw around, and the workability was very bad.

  The present invention has been made in view of the above reasons, and its purpose is to provide a TV set installed in a room separated from the same floor or a higher floor from a doorphone main unit with a TV without degrading the image quality. An object of the present invention is to provide a television door phone device that can reduce the wiring of the bus wiring to the door phone secondary master unit and can improve the workability.

According to a first aspect of the present invention, there is provided a doorphone slave unit having a television camera for imaging a visitor, a doorphone master unit with a television for projecting an image captured by the television camera, and connected to the doorphone master unit via a cable. A TV door phone device comprising a TV-equipped door phone sub-master device that receives a video signal from the door phone master device and displays a video image , wherein the output impedance of the door phone master device is larger than the characteristic impedance of the cable. the indoor apparatus is amplified video signal amplifier circuit, a output to the collector of the transistor of the emitter grounded amplifier circuit unbalanced video signal having an emitter grounded amplifier circuit including a tiger Njisuta - performing equilibrium conversion a video signal output transformer circuit connected to the transformer primary side, the video signal output in the indoor apparatus Two bus lines connected via a pair of connection terminals directly connected to one sub-master multiplex circuit on the secondary side of the lance circuit are provided, and as the termination device for terminating each of the bus lines, characterized by comprising providing a doorphone sub master unit having a termination device having substantially the same impedance as the characteristic impedance of the cable to the farthest end of each of the bus lines.

According to the present invention, since the video signal is output in a balanced manner by the transformer, it is not easily affected by the common mode noise, and the output impedance of the doorphone master unit is made larger than the characteristic impedance of the cable so that the doorphone master unit can A video signal amplifying circuit having a grounded-emitter amplifier circuit including a transistor and amplifying a video signal, and a primary side of a transformer for output and unbalanced-balanced conversion is connected to a collector of the transistor of the grounded-emitter amplifier circuit. Two systems having a video signal output transformer circuit and connected via a pair of connection terminals directly connected to one secondary master unit multiplexing circuit on the secondary side of the video signal output transformer circuit in the doorphone master unit of the bus lines is provided, the characteristic impedance substantially equal to the cable as a termination device for terminating each said bus line Since the doorphone sub master unit having a termination device for impedance provided in the farthest end of each of the bus lines, it without the line impedance of the cable or cause an impedance mismatch between the termination lowered, the video signal image quality degradation is small or et al reflection, without image degradation can be reduced routing of wiring to doorphone sub master unit, it is possible to improve the workability.

In the present invention, since the video signal is balanced output by the transformer, less susceptible to common-mode noise, also the output impedance of the indoor apparatus is larger than the characteristic impedance of the cable, the indoor unit is a tiger Njisuta A video signal amplifying circuit for amplifying a video signal having a grounded-emitter amplifier circuit, and a video signal in which a primary side of a transformer for unbalance-balance conversion is connected to a collector of a transistor of the grounded-emitter amplifier circuit. Two buses having an output transformer circuit and connected via a pair of connection terminals directly connected to one secondary master unit multiplexing circuit on the secondary side of the video signal output transformer circuit in the door phone master unit wiring provided, is substantially equal in the characteristic impedance of the cable as a termination device for terminating each said bus line Since the doorphone sub master unit having a termination device of Sudan scan provided farthest end of each of the bus lines, it without the line impedance of the cable or cause an impedance mismatch between the termination lowered, the video signal image quality degradation is small or et al reflections, it is possible to reduce the routing of the wiring to the doorphone sub base unit without image quality degradation, there is an effect that it is possible to improve the workability.

  First, a reference example of an embodiment described later will be described, and then the embodiment will be described.

(Reference Example 1)
As shown in FIGS. 4 and 5, in the TV door phone device of this reference example, two systems of bus wiring terminated with an impedance substantially equal to the characteristic impedance of the cable are provided from the door phone master unit 20 to the door phone sub master unit 30. It is characterized by that. The basic configuration of the doorphone slave unit 10, the doorphone master unit 20, and the dohoan sub-master unit 30 is substantially the same as the conventional configuration shown in FIGS. 9, 10, and 11, and the description thereof is omitted.

  A doorphone slave device 10 with a camera that captures an image of the entrance of the dwelling unit A is connected to a doorphone master device 20 with a TV set in the dwelling unit A via a cable 40. Moreover, the doorphone sub-master device 30 with a television set installed in each room on the same floor and the upper floor in the dwelling unit A is connected to the doorphone master device 20 via the cable 50 by bus wiring. Here, in this reference example, the bus wiring to each doorphone sub-master device 30 is wired in two lines from the doorphone master device 20, and the termination of the cable 50 of each system is terminated by a termination device 60. . For this reason, regardless of the output impedance of the video signal from the doorphone master unit 20, image quality deterioration due to reflection of the video signal at the end of each cable does not occur. The termination device 60 is constituted by a resistor having a magnitude equal to the characteristic impedance of the cable, for example.

  In this reference example, since two bus wirings terminated with an impedance substantially equal to the characteristic impedance of the cable 50 are provided from the doorphone master unit 20 to the doorphone sub-master unit 30, the same floor or upper level is maintained without image quality deterioration. Wiring to other rooms on the floor can be reduced and workability can be improved.

(Reference Example 2)
The basic configuration of this reference example is substantially the same as the conventional configuration, and the video signal transmission circuit 205 in the doorphone master unit 20 is configured as shown in FIG. 6, and the bus wiring from the doorphone master unit 20 to the doorphone submaster unit 30 is provided. The difference is that the system can be switched between one system and two systems. The basic configurations of the doorphone slave unit 10 and the Dohoan secondary master unit 30 are substantially the same as the conventional configurations shown in FIGS. Also, in the door phone base unit 20, the same components as those in the conventional configuration are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 6, the video signal transmission circuit 205 in the door phone master unit 20 in this reference example includes a video signal output bandpass filter 221 for removing signals other than the transmission frequency band of the video signal, and a transistor Q _0. An amplification circuit that amplifies the video signal output from the video signal output bandpass filter 221, an unbalance-balance conversion transformer 222 for performing unbalance-balance conversion of the two-wire transmission line, and a video buffer amplifier 204, a terminal 246 for connecting to the sub-master unit multiplexing circuit 215, and a switch 223 for switching on / off depending on whether the bus wiring is one or two systems.

In this reference example, when the characteristic impedance of the cable 50 (two-wire balanced cable) is r ₀ , the resistance value of the resistor R _{0 in} FIG. 6 is set to r ₀ . Further, the choke coil L in FIG. 6 is configured such that the impedance thereof is sufficiently larger (Z ₁ ) than the characteristic impedance r _{0 of the} cable 50 in the transmission frequency band of the video signal.

In this reference example, when the bus wiring in the dwelling unit is one system, the installer operates the switch 223 to turn it on. When the switch 223 is turned on, the output impedance of the video signal transmission circuit 205 becomes the combined impedance of the choke coil L and the resistor R ₀ (a value approximately equal to r ₀ ), and the impedance is substantially equal to the characteristic impedance of the cable 50. be able to.

Incidentally, in the circuit shown in FIG. 6, the resistance value of the resistor R ₀₁ is set to r _0/2 , and the video signal has the amplification factor set to 2 (= R ₀ / R ₀₁ ). However, this is because the signal is halved at the end of the bus wiring terminated by the termination device 60 (impedance r ₀ ).

Further, when the bus wiring in the dwelling unit has two systems, the installer operates the switch 223 to turn it off. When the switch 223 is turned off, the output impedance of the video signal transmitting circuit 205 can be made greater impedance than the characteristic impedance r ₀ of Z _1, and the cable 50.

  Further, the doorphone master unit 20 may be configured to detect whether or not two systems of cables are connected, and to control the switch 223. FIG. 7 shows an example of the configuration. In the doorphone master unit 20 shown in FIG. 7, whether or not the second-system cable 50 is connected to the connection terminal 224 is detected by the two-system connection detection circuit 225, and the CPU 213 detects from the two-system connection detection circuit 225. Based on this detection signal, a control signal for turning on / off the switch 223 is output.

  That is, the door phone base unit 20 is provided with a connection terminal 224 for connecting the second system bus wiring (cable 50) in addition to the connection terminal 220 for connecting the first system bus wiring (cable 50). In addition, a two-system connection detection circuit 225 that detects whether the second-system cable 50 is connected to the connection terminal 224 is provided. Similarly to the connection terminal 220, the connection terminal 224 is connected to the sub-master device multiplexing circuit 215. The two-system connection detection circuit 225 may be configured to detect, for example, that the cable 50 is inserted into the connection terminal 224 with a mechanical switch, or between the lines of the cable 50 connected to the connection terminal 224. The second cable 50 may be electrically detected by measuring the voltage or the like.

  Therefore, in this reference example, the output impedance of the amplifier circuit in the video signal transmission circuit 205 is set to an impedance substantially equal to the characteristic impedance of the cable 50 when the bus wiring in the dwelling unit is one system, and the bus impedance is two systems. By making the impedance larger than the characteristic impedance of the cable 50, it is possible to prevent image quality deterioration due to the reflection of the video signal regardless of whether the bus wiring in the dwelling unit is one system or two systems.

(Embodiment)
FIG. 1 shows a schematic configuration diagram of the television door phone device of the present embodiment. The basic configuration of the doorphone slave unit 10 and the doorphone sub-master unit 30 is the same as the conventional configuration, and thus the description thereof is omitted. The doorphone master device 20 in FIG. 1 has a configuration as shown in FIG. 2. In this embodiment, two systems of bus wiring (cable 50) are connected to the connection terminal 220, and the doorphone sub-master device 30 is connected to each bus wiring. Are connected, and each system is short-circuited by the terminating device 60. Note that the audio circuit 229 in FIG. 1 includes the 2-wire 4-wire conversion circuit 206, the handset 209, the call switch 211, the reception amplifier 207, and the transmission amplifier 208 of FIG. Further, the control circuit 230 in FIG. 1 includes the call button press detection circuit 212, the CPU 213, and the control signal modulation / demodulation circuit 214 in FIG. Further, the power supply circuit 231 in FIG. 1 includes the child device DC power supply superimposing circuit 216, the power supply circuit 217, and the sub master unit DC power superimposing circuit 218 in FIG. Note that the door phone base unit 20 in this embodiment has the same configuration as the conventional configuration except for the video signal detection circuit 70, and therefore, the same reference numerals are given to the same components as those in the conventional configuration, and the description thereof is omitted.

  As shown in FIG. 3, the video signal output circuit 70 includes a video signal amplification circuit 227 that amplifies the video signal that has passed through the video signal bandpass filter 226 and a video signal output transformer circuit 228. The video signal band filter 226 is a filter for passing only the transmission frequency band of the video signal (FM video signal) so as not to emit unnecessary radiation.

Here, a video signal amplifier circuit 227 is composed of an emitter grounded amplifier circuit including a transistor Q _1, and an emitter follower circuit including a transistor Q _2. Grounded emitter amplifier circuit is intended to compensate for the insertion loss of the transformer T ₁ of the power loss and later by outputting a video signal in a high impedance, an emitter follower circuit, the capacitance between the base and emitter of the transistor Q ₁ The impedance conversion circuit is configured to prevent impedance mismatch between the video signal amplifying circuit 227 and the video signal bandpass filter 226 due to a decrease in impedance due to the above.

In the video signal output transformer circuit 228, the secondary side of the transformer T ₁ is connected to the cable 50 via the capacitors C ₂ and C ₃ and the sub-master unit multiplexing circuit 215. Here, as shown in FIG. 1, at least one doorphone sub-master device 30 is connected to the cable 50.

The transformer T ₁ has a primary side connected in series between the resistor R ₄ and the collector of the transistor Q ₁ . Resistor R _4, the voltage difference between the voltage and the collector voltage of the transistor to Q ₁ power supply Vcc is set to be larger than the amplitude of the video signal, the video signal is to set the operating point of the video signal amplifier circuit 227 so as not to saturate Is for.

By the way, the transformer T ₁ is configured such that the inductance value thereof has an impedance Z sufficiently larger than the characteristic impedance Z ₀ of the cable 50 in the frequency band of the video signal. Furthermore, since the impedance Z is the frequency of the video signal f, when the inductance value of the transformer _{T 1} is L, the Z = 2.pi.fL.

Now, the DC gain of the video signal amplifier circuit 227 Gd, and the resistance value of the emitter resistor RE of the transistor _{Q 1} re, the resistance value of the resistor _{R 4} and _{r 4,} the Gd ₌ r 4 / re.

The capacitor C ₁ connected in parallel with the resistor R ₄ has a frequency band of the video signal so that the AC gain G of the video signal amplifier circuit 227 becomes a ratio of the impedance Z on the primary side of the transformer T ₁ and the resistance value re of the emitter resistor RE. in is for bypassing the resistor R _4, having a sufficiently small impedance value in a frequency band of the video signal. Therefore, the AC gain G in the frequency band of the video signal is G = Z / re.

By the way, although each cable 50 is short-circuited by the termination device 60 as described above, the termination device 60 is short-circuited with an impedance equal to the characteristic impedance Z ₀ of the cable 50. On the other hand, the impedance Z described above is a sufficiently large impedance than the impedance Z _0, the impedance Z of the primary side of the transformer T ₁ is a Z ≒ Z _0/2. Therefore, impedance viewed cable 50 side from the video signal output circuit 70 is substantially Z _0/2, and the impedance viewed video signal output circuit 70 side from the cable 50 side sufficiently larger than Z ₀ (for example, 10 times or more) Value.

  Therefore, also in the present embodiment, it is possible to reduce the routing of wiring to other rooms on the same floor or upper floor without deterioration in image quality, and to improve the workability.

Further, in the television door phone apparatus of the present embodiment, when only one bus wiring (cable 50) to which the door phone sub-master unit 30 is connected is wired from the door phone master unit 20, the farthest end of the cable 50 is the characteristic of the cable 50. with terminating in termination device 60 with impedance equal to the impedance Z _0, by connecting an element having the same impedance as the characteristic impedance Z ₀ of the cable 50 also between the output terminal of the indoor apparatus 20 (connecting terminal 220), What is necessary is just to impedance match the both ends of the cable 50. FIG. Therefore, there is no need to switch the circuit of the door phone master unit 20 between the case of one system and the system of two systems as in the reference example 2, and the circuit configuration can be simplified because it can be changed only by detaching the terminal impedance. Cost reduction can be achieved.

It is a schematic block diagram which shows embodiment. It is a block diagram of the door phone main unit in the same as the above. It is a principal part circuit diagram of the door phone main unit in the same as the above. FIG. 7 is a diagram illustrating a reference example 1 and bus wiring in a dwelling unit. It is other explanatory drawing which shows the same as the above and the bus wiring in a dwelling unit. 10 is a block diagram illustrating a video signal transmission circuit used in Reference Example 2. FIG. It is a block diagram which shows the main | base station used for the reference example 2. FIG. It is a block diagram which shows an example of the conventional television door phone apparatus. It is a block diagram which shows an example of the door phone cordless handset used for the same as the above. It is a block diagram which shows an example of the door phone main unit used for the same as the above. It is a block diagram which shows an example of the door phone submaster used for the same as the above. It is explanatory drawing of the bus wiring in a dwelling unit same as the above. It is other explanatory drawing of the bus wiring in a dwelling unit same as the above.

Explanation of symbols

10 doorphone entrance station 20 indoor apparatus 30 doorphone sub master unit 40 Cable 50 Cable 60 termination device 70 a video signal output circuit 227 video signal amplifier circuit 228 video signal output transformer circuit T ₁ trans Q ₁ transistor

Claims (1)

Doorphone slave unit having a TV camera for capturing a visitor, a doorphone master unit with a TV for displaying images captured by the TV camera, and images from the doorphone master unit connected to the doorphone master unit via a cable A TV doorphone device comprising a TV-equipped doorphone sub-master device that receives a signal and displays an image , wherein the output impedance of the doorphone master device is larger than the characteristic impedance of the cable, and the doorphone master device is connecting a primary side of a transformer performing balance conversion - video signal amplifier circuit for amplifying a video signal has a grounded emitter amplifier circuit, the emitters be for output to the collector of the transistor of the amplifier circuit imbalance including tiger Njisuta secondary to have a video signal output transformer circuit, a video signal output transformer circuit in the indoor apparatus One of the bus lines of two systems are connected via a pair of directly connected connection terminal multiplexer for the sub master unit is provided, the characteristic impedance of the cable as a termination device for terminating each said bus line and stands for It is provided with equal impedance doorphone sub master unit having a termination device to the farthest end of each of the bus lines TV door apparatus according to claim.

Images