JP2008311706A - Optical network terminating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical network terminating device capable of transmitting both of the analog broadcast waves of an VHF band inputted as electric signals and the digital broadcast waves of an UHF band inputted as optical signals. <P>SOLUTION: A protector 1 is provided with an optical signal input part 11 to which the optical signals are inputted, an electric signal input part 12 to which the electric signals are inputted, a signal mixing part 13 for mixing the signals inputted to the optical signal input part 11 and the signals inputted to the electric signal input part 12, and a signal output part 14 for outputting the signals mixed by the signal mixing part 13. The optical signal input part 11 is provided with a photoelectric conversion part 111 for converting the optical signals into the electric signals. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical network termination device that converts a received optical signal into an electrical signal and outputs the electrical signal to a TV receiver or the like.

  In recent years, in the TV (Television) broadcasting system, a shift from an analog system that uses radio waves in the VHF (Very High Frequency) band to a digital system that uses radio waves in the UHF (Ultra High Frequency) band is underway. In the end, although all TV broadcasts are planned to be transferred to the digital system, in order to secure the period required for the maintenance of broadcasting facilities such as transmitting stations and relay stations, and the spread of digital-compatible receivers, A transition period in which an analog method and a digital method coexist is set.

  By the way, conventionally, when a TV wave is interrupted by a building such as a high-rise condominium, if a radio wave interference occurs around the building, an appropriate TV broadcast wave is transmitted to the surrounding housing where the radio wave interference has occurred. In some cases, a radio wave interference countermeasure facility was established. This radio wave interference countermeasure facility transmits a TV broadcast wave by a coaxial cable from an antenna installed at a position where a sufficiently strong TV broadcast wave can be received to a house that is the target of the radio wave interference countermeasure. In each house, a coaxial cable for transmitting a TV broadcast wave is drawn into each house through a protector for interrupting an abnormal voltage caused by a lightning strike or the like. (For example, refer to Patent Document 1).

JP 2000-115994 A

  Here, in the transition period in which the analog system and the digital system of TV broadcasting coexist, it is required that both types of TV broadcasting waves can be transmitted to each house using the radio wave interference countermeasure facility. .

  However, the conventional radio wave interference countermeasure facility has a problem that the UHF band digital broadcast wave is attenuated by the transmission loss of the coaxial cable, and a sufficient signal level is not maintained.

  On the other hand, the digital broadcast wave received by the antenna of the radio interference countermeasure facility is converted into an optical signal, and then the optical signal is transmitted to the surrounding houses through an optical cable, and is optically transmitted by an optical network termination device provided in each house. By converting the signal into an electrical signal, it is possible to receive digital broadcast waves in each house. However, in an optical network broadcast system, there is a possibility that an analog broadcast wave is not included in an optical signal because an equipment for receiving an analog broadcast is not provided for the convenience of the optical transmitter. In that case, it is necessary to draw two different systems, digital and analog, into the house and wire them in each room, and it is necessary to consider privacy protection. It was.

  The present invention has been made in view of the above, and is an optical network termination capable of transmitting both VHF band analog broadcast waves input as electrical signals and UHF band digital broadcast waves input as optical signals. An object is to provide an apparatus.

  In order to solve the above-described problems and achieve the object, an optical network termination device according to claim 1 includes a first system to which an optical signal is input, a second system to which an electrical signal is input, A signal mixing unit that mixes a signal input to the first system and a signal input to the second system; and a third system that outputs a signal mixed by the signal mixing unit. The first system includes photoelectric conversion means for converting an optical signal into an electric signal.

  The optical network termination device according to claim 2 is the optical network termination device according to claim 1, wherein the electrical signal transmission means is configured to apply a voltage of a predetermined value or more to the electrical signal transmission means. And a protection means for cutting off a current generated with the voltage.

  An optical network termination device according to claim 3 is the optical network termination device according to claim 1 or 2, wherein the signal mixing means includes a high-pass filter and a low-pass filter.

  An optical network termination device according to claim 4 is the optical network termination device according to any one of claims 1 to 3, wherein a broadcast signal in the UHF band is input to the first system as an optical signal. The second system is characterized in that a VHF band broadcast signal is input as an electrical signal.

  The optical network termination device according to claim 5 is the optical network termination device according to any one of claims 1 to 4, wherein the photoelectric conversion means is a photodiode that performs photoelectric conversion in a solar cell mode. And a capacitor for extracting only the AC component of the signal output from the photodiode, and an output terminal for outputting the AC component signal extracted via the capacitor.

  According to the first aspect of the present invention, an optical signal is input to the first system and an electric signal is input to the second system, whereby the signal input as the optical signal and the electric signal are input. A signal obtained by mixing the received signal can be output from the third system. Thereby, since the optical signal can be transmitted to the house where the optical network termination device is installed by the optical cable, the optical signal can be transmitted to the house while maintaining the signal level at a sufficient level. In addition, an electrical signal transmitted by a coaxial cable can be transmitted to the house. Also, even if the content of the broadcast signal is changed in the future, such as when the TV broadcast system will be digital only, it can be easily handled by changing the connection configuration in the optical network termination device, which facilitates maintenance work. Become.

  Further, according to the present invention of claim 2, since the protection means is provided, when a surge voltage is applied to the optical network termination device due to a lightning strike or the like, the optical network termination device is placed downstream. It is possible to prevent dielectric breakdown of connected electronic devices.

  According to the third aspect of the present invention, since the signals are mixed using the high-pass filter and the low-pass filter, the signal that interferes with each other of the mixed signals is removed, and then the signal is Can be mixed without causing any loss.

  According to the present invention, the UHF band digital broadcast signal is input to the first system as an optical signal, and the VHF band analog broadcast signal is supplied to the second system as an electrical signal. By inputting the signal, a signal obtained by mixing the digital broadcast signal and the analog broadcast signal can be output from the signal output unit. As a result, the UHF band digital broadcast wave transmitted from the radio wave interference prevention facility by the optical cable to the house where the optical network termination device is installed is transmitted to the house with the signal level maintained at a sufficient level. Can do. In addition, analog broadcast waves in the VHF band transmitted from the radio wave interference prevention facility through coaxial cables can be transmitted to the house as before.

  According to the fifth aspect of the present invention, by operating the photoelectric conversion means with no voltage applied, it is not necessary to supply power to the optical network termination device, and a digital broadcast signal and an analog broadcast signal are transmitted. be able to.

  Embodiments of an opening / closing system according to the present invention will be described below in detail with reference to the accompanying drawings. [I] First, the basic concept of each embodiment will be described, then [II] the specific contents of each embodiment will be described, and [III] Finally, modifications to each embodiment will be described. However, the present invention is not limited to each embodiment.

[I] Basic concept of each embodiment First, a basic concept common to each embodiment will be described. The optical network termination device according to each embodiment converts a UHF band digital broadcast wave input as an optical signal into an electrical signal and transmits it in a house, and a VHF band analog input as an electrical signal. The purpose is to transmit broadcast waves into the house. The specific configuration of the optical network termination device is arbitrary, but in the following, a case where the optical network termination device is configured as a protector for interrupting an abnormal voltage due to a lightning strike will be described as an example.

  One of the features of the protector according to each embodiment is that a first system in which a UHF band digital broadcast wave is input via an optical cable and a VHF band analog broadcast wave are input through a coaxial cable. There are two input systems with the second system, and a third system for mixing and outputting signals input to the two input systems. As a result, the UHF band digital broadcast wave input as an optical signal through the optical cable can be transmitted into the house, and the VHF band analog broadcast wave input through the coaxial cable can be transmitted into the house as before. Can be transmitted.

[II] Specific Contents of Each Embodiment Next, specific contents of each embodiment according to the present invention will be described.

[Embodiment 1]
First, the first embodiment will be described. This form is a basic form that includes first, second, and third systems and includes signal mixing means and photoelectric conversion means.

(Configuration of protector)
First, the configuration of the protector will be described. FIG. 1 is a schematic diagram showing an installation example of a protector, FIG. 2 is an external view of the protector, and FIG. 3 is a block diagram functionally conceptually showing the electrical configuration of the protector. As shown in FIG. 1, the protector 1 is installed outdoors or indoors in a house 2. An optical cable 4 and a coaxial cable 5 are connected to the protector 1 from the radio wave interference countermeasure facility 3 to each house 2 that uses the radio wave interference countermeasure facility 3. The protector 1 and the indoor TV receiver 6 are connected by a coaxial cable 5. Here, the optical cable 4 transmits a UHF band digital broadcast wave, and the coaxial cable 5 transmits a VHF band analog broadcast wave.

  The protector 1 includes a substantially cylindrical casing 10 as shown in FIG. The housing 10 includes a base plate 10a that forms one end surface of the housing 10 and a cover 10b that forms the other end surface and a peripheral surface. An optical connector 110 and a coaxial connector 120 described later are disposed on the base plate 10a. The base plate 10a is provided with a substantially L-shaped mounting bracket 10c, and the housing 10 can be fixed to the wall surface of the house 2 or the like via the mounting bracket 10c. Thus, when the housing | casing 10 is fixed to a wall surface, the base board 10a becomes the end surface of the vertical direction lower side in the housing | casing 10. FIG. Therefore, since the connector arranged on the base plate 10a can be protected from raindrops and the like by the cover 10b positioned above the base plate 10a, the protector 1 can be installed outdoors. is there.

  As shown in FIG. 3, the protector 1 includes an optical signal input unit 11, an electric signal input unit 12, a signal mixing unit 13, and a signal output unit 14 inside the housing 10.

(Structure of protector-optical signal input unit 11)
The optical signal input unit 11 is a part to which a UHF band digital broadcast signal transmitted by the optical cable 4 is input, and corresponds to the first system in the claims. The optical signal input unit 11 includes an optical connector 110 and a photoelectric conversion unit 111. The optical connector 110 is a connection means to which the optical cable 4 is connected, and an optical signal is input from the optical cable 4 through the optical connector 110. The photoelectric conversion unit 111 converts an optical signal input via the optical connector 110 into an electrical signal, and corresponds to the photoelectric conversion means in the claims.

  FIG. 4 shows a circuit diagram of the photoelectric conversion unit 111. The photoelectric conversion unit 111 performs impedance matching with a PD (Photo Diode) 112 for converting an optical signal into an electric signal, a resistor 113 for reducing the inter-terminal capacitance of the PD 112, and a subsequent device of the photoelectric conversion unit 111. Resistor 114, AC coupling capacitor 116 and capacitor 117, a coil 118 for circulating the DC component of the current of PD 112 to PD 112 and minimizing the DC component, and an output terminal for outputting the converted electric signal 115. The photoelectric conversion unit 111 can perform photoelectric conversion without applying a reverse voltage to the PD 112 from an external power source. That is, the PD 112 can be operated in a so-called solar cell mode. Specifically, when light energy exceeding the energy band gap is incident on the PD 112, the light energy is absorbed by the depletion layer at the junction of the PD 112, and generation and drift of conduction electrons and holes are performed. Thus, an electromotive force proportional to the light intensity is generated. Only the AC component of this electromotive force is output to the output terminal 115 when the DC component is dropped by AC coupling by the capacitor 116 and the capacitor 117. Therefore, an electric signal can be taken out from the output terminal 115 and supplied to the subsequent stage side.

(Structure of protector-electric signal input unit 12)
The electric signal input unit 12 is a portion to which a VHF band analog broadcast signal transmitted by the coaxial cable 5 is input, and corresponds to the second system in the claims. The electrical signal input unit 12 includes a coaxial connector 120 and a lightning protection circuit 121. The coaxial connector 120 is a connection means to which the coaxial cable 5 is connected, and an electrical signal is input from the coaxial cable 5 through the coaxial connector 120.

  When a surge voltage is generated in the radio wave interference countermeasure facility 3 due to a lightning strike or the like, the surge voltage is applied to the electrical signal input unit 12 via the coaxial cable 5 connected to the coaxial connector 120. The lightning protection circuit 121 cuts off the current generated with the surge voltage applied to the electrical signal input unit 12 from the circuit subsequent to the lightning protection circuit 121, and corresponds to the protection means in the claims. ing. The specific configuration of the lightning protection circuit 121 is well known and will not be described here. For example, a current generated with a surge voltage can be supplied to the ground line.

(Structure of protector-signal mixing unit 13)
The signal mixing unit 13 is for mixing the electric signal converted and output from the optical signal by the photoelectric conversion unit 111 and the electric signal input via the coaxial connector 120. The signal in the claims It corresponds to the mixing means. The signal mixing unit 13 includes a high-pass filter (not shown) and a low-pass filter (not shown). The high-pass filter removes a noise component on the lower frequency side than the frequency band of the digital broadcast signal in the digital broadcast signal output from the photoelectric conversion unit 111 and passes only a signal component on the high frequency side including the digital broadcast signal. . The low-pass filter removes noise components on the higher frequency side than the frequency band of the analog broadcast signal in the analog broadcast signal input via the coaxial connector 120, and passes only the signal component on the lower frequency side including the analog broadcast signal. Let By synthesizing the electric signals that have passed through the high-pass filter and the low-pass filter, the UHF band digital broadcast signal and the VHF band analog broadcast signal can be mixed without causing loss.

(Configuration of protector-signal output unit 14)
The signal output unit 14 is for outputting the UHF band digital broadcast signal and the VHF band analog broadcast signal mixed by the signal mixing unit 13, and corresponds to the third system in the claims. . The signal output unit 14 includes a coaxial connector 140 to which the coaxial cable 5 is connected. From the coaxial connector 140, a UHF band digital broadcast signal and a VHF band analog broadcast signal are output to the TV receiver 6 or the like of the house 2 through the coaxial cable 5 connected to the coaxial connector 140.

(Effect of Embodiment 1)
As described above, according to the first embodiment, the UHF band digital broadcast signal is input to the optical signal input unit 11 as an optical signal, and the VHF band analog broadcast signal is input to the electric signal input unit 12 as an electric signal. Thus, the signal output unit 14 can output a signal obtained by mixing the digital broadcast signal and the analog broadcast signal. As a result, the digital broadcast wave in the UHF band can be transmitted from the radio wave interference countermeasure facility 3 to the house 2 in which the protector 1 is installed by the optical cable 4, so that the signal level of the digital broadcast wave is maintained at a sufficient level. Can be transmitted to the inside of the house 2. Also, analog broadcast waves in the VHF band transmitted from the radio wave interference countermeasure facility 3 through the coaxial cable 5 can be transmitted to the house 2 as in the past. Further, both the digital broadcast signal and the analog broadcast signal can be taken into the house 2 with a simple connection configuration. Furthermore, when analog broadcasting stops in the future, the coaxial cable 5 connected to the coaxial connector 120 of the electric signal input unit 12 may be removed and the termination process of the coaxial connector 120 may be performed. The corresponding connection can be easily performed.

  In addition, since it is not necessary to apply a reverse voltage to the PD 112 of the photoelectric conversion unit 111, it is not necessary to supply the power of the protector 1. Therefore, no power source is required, and it is easy to perform installation work in each house 2.

  In addition, since the lightning protection circuit 121 is provided, when a surge voltage is applied to the protector 1 due to lightning or the like, it is possible to prevent dielectric breakdown of an electronic device connected downstream from the protector 1. can do. In addition, since the protector 1 is often installed outdoors, it is possible to perform maintenance work without entering indoors according to changes in broadcast contents.

  Moreover, since the UHF band digital broadcast signal and the VHF band analog broadcast signal are mixed using a high pass filter and a low pass filter, noise that may interfere with each signal is removed, and signal loss is lost. It is possible to mix without generating.

[Embodiment 2]
Next, a second embodiment will be described. In this form, a reverse voltage is applied to the PD.

  The configuration of the second embodiment is substantially the same as the configuration of the first embodiment except where otherwise specified, and the same configuration as that of the first embodiment is used in the first embodiment. The same reference numerals and / or names are attached as necessary, and the description thereof is omitted.

  FIG. 5 is a circuit diagram of the photoelectric conversion unit 111 according to the second embodiment. As illustrated in FIG. 5, the photoelectric conversion unit 111 includes a resistor 114, a resistor 150, and a capacitor 116. Since a reverse voltage of + Vcc is applied to PD 112, a depletion layer is formed at the junction of PD 112. In this state, when light energy exceeding the energy band gap is incident from the outside of the PD 112, this light energy is absorbed by the depletion layer at the junction of the PD 112, and generation and drift of conduction electrons and holes are performed. Thus, a current (reverse current) proportional to the light intensity flows and photoelectric conversion can be performed. Thus, the AC component in the signal output from the PD 112 can be extracted by AC coupling by the capacitor 116 and supplied to the subsequent stage side. In addition, the electric power for applying a reverse voltage to PD112 can be supplied from the power supply etc. which are not shown in the house 2, for example.

(Effect of Embodiment 2)
As described above, according to the second embodiment, in addition to the basic effects in the first embodiment, since a reverse voltage is applied to the PD 112, high-quality signal transmission excellent in signal high-speed performance and distortion performance is achieved. Can be performed.

[III] Modifications to Each Embodiment While each embodiment according to the present invention has been described above, the specific configuration and means of the present invention are the same as the technical idea of each invention described in the claims. Modifications and improvements can be arbitrarily made within the range. Hereinafter, such a modification will be described.

(About problems to be solved and effects of the invention)
First, the problems to be solved by the invention and the effects of the invention are not limited to the above-described contents, and the present invention solves the problems not described above or has the effects not described above. There are also cases where only some of the described problems are solved or only some of the described effects are achieved. For example, even when a UHF band digital broadcast signal and a VHF band analog broadcast signal cannot be mixed and transmitted simultaneously in a house, a UHF band digital broadcast signal as an optical signal or an electric signal When an analog broadcast signal in the VHF band is input to the optical network termination device, it can be said that the object of the present invention has been achieved as long as any signal can be transmitted into the house.

(About optical network termination equipment)
The optical network termination device according to the present invention is not limited to a radio wave interference countermeasure facility, and can be applied to a termination portion of an arbitrary transmission network that transmits a signal using an optical cable and a coaxial cable.

  The optical network termination device according to the present invention can be applied to an optical network termination device that converts a received optical signal into an electrical signal and outputs the electrical signal to a TV receiver or the like. This is useful for an optical network terminator capable of transmitting both UHF band digital broadcast waves input as optical signals.

It is the schematic which showed the example of installation of a protector. It is an external view of a protector. It is the block diagram which showed the electrical structure of the protector functionally. 3 is a circuit diagram of a photoelectric conversion unit 111. FIG. 3 is a circuit diagram of a photoelectric conversion unit 111. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Protector 2 Housing 3 Facility for radio wave interference 4 Optical cable 5 Coaxial cable 6 TV receiver 10 Housing 10a Base plate 10b Cover 10c Mounting bracket 11 Optical signal input unit 12 Electric signal input unit 13 Signal mixing unit 14 Signal output unit 110 Light Connector 111 Photoelectric converter 112 PD
113, 114, 150 Resistance 115 Output terminal 116, 117 Capacitor 118 Coil 120, 140 Coaxial connector 121 Lightning protection circuit

Claims (5)

A first system to which an optical signal is input;
A second system to which an electrical signal is input;
Signal mixing means for mixing the signal input to the first system and the signal input to the second system;
A third system for outputting the signal mixed by the signal mixing means,
The first system includes photoelectric conversion means for converting an optical signal into an electrical signal;
An optical network termination device. The electrical signal transmission means includes a protection means for cutting off a current generated with the voltage when a voltage of a predetermined value or more is applied to the electrical signal transmission means.
The optical network termination device according to claim 1. The signal mixing means comprises a high-pass filter and a low-pass filter;
The optical network termination device according to claim 1 or 2. A UHF band broadcast signal is input as an optical signal to the first system, and a VHF band broadcast signal is input as an electrical signal to the second system.
The optical network termination device according to any one of claims 1 to 3. The photoelectric conversion means includes
A photodiode that performs photoelectric conversion in solar cell mode;
A capacitor that extracts only the AC component of the signal output from the photodiode;
An output terminal for outputting an AC component signal taken out through the capacitor;
The optical network termination device according to any one of claims 1 to 4, wherein:

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