JP6034686B2 - Optical receiver - Google Patents

Description

  The present invention relates to an optical receiver, and more particularly to an optical receiver for CATV that receives a television broadcast, a notification broadcast, or the like from a center through an optical transmission line, converts it into an electrical signal, and outputs the electrical signal.

  Conventionally, optical transmission systems using optical cables have become widespread. According to this optical transmission system, relayless transmission of about several tens of kilometers can be performed, so that the transmission system can be easily widened. This optical transmission system generally includes an optical transmitter arranged on the sender side and an optical receiver (ONU: Optical Network Unit) arranged on the receiver side for a long distance constituted by an optical cable. Are connected via an optical transmission line. Then, the TV signal is mixed on the transmitter side, the mixed electric signal is converted into an optical signal by the optical transmitter, and the optical signal is transmitted to the optical receiver via the optical transmission path. In this optical receiver, the optical signal is converted into an electrical signal and output to the television receiver. Specifically, this optical receiver incorporates a photoelectric conversion circuit including a PD (Photo Diode) for converting an optical signal into an electric signal. By applying a reverse voltage to this PD, the PD A current (reverse current) proportional to a change in light intensity of light energy incident on the light flows, and photoelectric conversion can be performed. Then, an AC component in the electric signal converted by the PD is extracted by AC coupling using a capacitor and is output to an output terminal (see, for example, Patent Document 1).

  Also, in recent cable TV optical receivers, it is necessary to supply power so that various signals such as TV broadcast signals and security broadcast signals transmitted from the center can be supplied to the receiver users even during power outages. There is a so-called non-feed type optical receiver that can output a signal photoelectrically / electrically converted by a photoelectric conversion circuit capable of photoelectric conversion to an external device. Since the parasitic optical receiver does not have a power source, it does not include a high-frequency amplifier that requires a power source. For this reason, the output signal of the photoelectric conversion circuit is not amplified but is output to an external device. (For example, refer to Patent Document 2).

JP 2006-174221 A JP 2009-033405 A

  In such an optical receiver, when an optical signal having a higher level than the limit value is input to the photoelectric conversion circuit including the PD, distortion occurs in the electric signal output from the photoelectric conversion circuit. In particular, a digital terrestrial broadcast signal using an OFDM signal is easily affected by distortion, and there is a problem that a broadcast cannot be displayed on a television receiver. For this reason, the level of the optical signal input to the photoelectric conversion circuit is regulated to input a signal having a level within a predetermined limited range so that distortion or the like does not occur. Since the parasitic optical receiver does not include a high-frequency amplifier, it is desired to output the signal from the photoelectric conversion circuit as high as possible. To that end, it is desirable to input an optical input level as high as possible to the photoelectric conversion circuit. . On the other hand, however, there is a problem that the higher the input level, the more susceptible to the S / N ratio of the output signal and the nonlinear distortion.

  As an example of measures to prevent the influence of nonlinear distortion even when a high-level optical signal exceeding the limit value is input to the photoelectric conversion circuit, an attenuator is inserted before the photoelectric conversion circuit. Although the input level may be attenuated, it simply results in signal loss and is inefficient as an energy transmission method.

  The present invention has been made in view of the above, and even when a high-level optical signal is input to the photoelectric conversion unit, generation of nonlinear distortion can be prevented and a signal of a desired output level can be output. An object is to provide an optical receiver.

In order to solve the above-described problems and achieve the object, an optical receiver according to claim 1 is an optical receiver for CATV that receives an optical signal and converts the optical signal into an electrical signal. Optical signal branching means for branching into a plurality of optical signals and outputting the branched optical signals through a plurality of optical transmission lines, and connected to the optical signal branching means and the plurality of optical transmission lines A plurality of photoelectric conversion means, a plurality of photoelectric conversion means for converting an optical signal branched by the optical signal branching means into an electrical signal, and each of the plurality of photoelectric conversion means and a plurality of transmission lines An electrical signal synthesis unit connected to the electrical signal synthesis unit for synthesizing the plurality of electrical signals converted by the plurality of photoelectric conversion units, and the plurality of electrical signals are synthesized by the electrical signal synthesis unit. The phases of the multiple electrical signals In so that, a phase adjusting means for adjusting at least part of the phase of at least part of the phase, or the plurality of electric signals of the plurality of optical signals, the phase adjusting means, the plurality of light Including a transmission line and the plurality of transmission lines, the plurality of optical transmission lines being formed to have substantially the same length, and connecting the optical signal branching unit and the plurality of photoelectric conversion units by a non-shortest path. The plurality of transmission lines are formed to have substantially the same length as each other, connect the plurality of photoelectric conversion means and the electric signal combining means through a non-shortest path, and only the optical signal as signal light is An optical signal branching means is inputted to branch to the plurality of optical signals without polarization, and the branched optical signals are inputted to the plurality of photoelectric conversion means without polarization to be converted into the plurality of electrical signals. Convert the converted multiple The air signal combining to by said electrical signal synthesizing means for outputting an optical receiver.

The optical receiver according to claim 2 is the optical receiver according to claim 1, wherein each of the plurality of photoelectric conversion means can be driven without supplying power.

An optical receiver according to a third aspect is the optical receiver according to the first or second aspect , wherein the plurality of photoelectric conversion means are connected in parallel to each other.

According to the optical receiver of claim 1, after the optical signal is branched into a plurality of optical transmission lines, the optical signal is converted into an electric signal by a plurality of photoelectric conversion means, and the plurality of electric signals are synthesized by the electric signal synthesizing means. In addition, at the time of synthesizing by the electric signal synthesizing means, at least part of the phase of the plurality of optical signals or at least part of the plurality of electric signals so that the phases of the plurality of electric signals are synchronized. Since the phase adjusting means for adjusting the phase is provided, it is possible to suppress the phase shift of the plurality of electric signals input to the electric signal synthesizing means, and to adjust the level of the electric signal synthesized by the electric signal synthesizing means. It can be maintained at a predetermined level. Therefore, the TV signal included in the electric signal can be transmitted to the television receiver while suppressing the influence of distortion.
Further, since the phase adjusting means includes a plurality of transmission lines formed to have substantially the same length as each other, a special component for suppressing a phase shift of the plurality of electric signals input to the electric signal synthesizing means is provided. It is no longer necessary to provide this, and the manufacturing cost of the optical receiver can be reduced.
In addition, since the phase adjusting means includes a plurality of optical transmission lines formed to have substantially the same length as each other, the phase adjusting means includes a special component for suppressing a phase shift of the optical signal input to each photoelectric conversion means. This is unnecessary, and the manufacturing cost of the optical receiver can be reduced.

Further, according to the optical receiver of the third aspect , since the plurality of photoelectric conversion means are connected in parallel to each other, it is built in the optical receiver as compared with the case where the plurality of photoelectric conversion means are connected in series to each other. The level of current flowing through the circuit board can be increased.

1 is a schematic diagram illustrating an optical receiver according to a first embodiment. 1 is a block diagram illustrating a configuration of an optical receiver according to a first embodiment.

  Embodiments of an optical receiver according to the present invention will be described below in detail with reference to the accompanying drawings. First, the configuration of the optical receiver will be described, then the operation of the optical receiver will be described, and finally, a modification to the embodiment will be described. However, the present invention is not limited by these embodiments. In addition, although the installation target and application object of the optical receiver which concerns on embodiment are arbitrary, below, the case where it applies to the optical receiver installed in the outdoor of a dwelling unit is demonstrated as an example.

[Embodiment 1]
First, the first embodiment will be described. In this embodiment, an optical signal including television broadcast is received from a cable television center device via an optical transmission path, branched into a plurality of optical transmission paths, and photoelectric conversion means provided in each optical transmission path is used for photoelectric conversion. This is an optical receiver that synthesizes electric signals after conversion, and has a configuration in which the phase adjustment of each electric signal is made into a plurality of transmission lines and a plurality of optical transmission lines formed to a predetermined length.

(Constitution)
FIG. 1 is a schematic diagram illustrating an optical receiver according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of the optical receiver according to the first embodiment. In the following description, the X direction in FIG. 1 is the left-right direction (or width direction), the Y direction in FIG. 1 is the front-rear direction, and the Z direction in FIG. 1 is the up-down direction (or height direction). The optical receiver 1 is a device that is housed in a housing (not shown) installed on an outdoor wall surface of a general house or the like and is connected to an optical communication network. Specifically, the optical receiver 1 is an optical transmitter (not shown) and an optical transmission line 11 (specifically, an optical fiber or the like) outside the housing 20 shown in FIG. 1 and the second optical transmission lines 16a to 16d), and a television receiver (not shown) and a transmission line 40 (specifically, a coaxial cable). , Signal lines on a circuit board, etc. Note that the same applies to first transmission lines 32a to 32d and second transmission line 34 described later. The optical receiver 1 includes an optical transmission line system 10 and a circuit board 30.

(Configuration-optical transmission line system)
The optical transmission line system 10 is a system that performs transmission processing for transmitting an optical signal transmitted from an optical transmitter to the optical receiver 1. Specifically, as shown in FIGS. 1 and 2, the optical transmission line system 10 is disposed outside the housing 20 shown in FIG. 1, and includes an optical input terminal 13, a first optical transmission line 14, and the like. The optical branching coupler 15 includes second optical transmission lines 16a to 16d and optical connectors 17a to 17d.

  The optical input terminal 13 is a terminal that receives an input of an optical signal output from the optical output terminal 12 connected to the optical transmission line 11. Specifically, as shown in FIGS. 1 and 2, the optical input terminal 13 is configured by, for example, a known male optical input terminal, and the optical output terminal 12 (for example, a known male optical output terminal). ) And a female connector via a female connector, and is also connected to the first optical transmission line 14.

  The first optical transmission line 14 is an optical transmission line that transmits the optical signal input from the optical input terminal 13 to the optical branching coupler 15.

  The optical branching coupler 15 branches the optical signal transmitted through the first optical transmission line 14 into a plurality of optical signals (in this embodiment, branches into four optical signals), and the branched optical signals are Optical signal branching means for outputting via the second optical transmission lines 16a to 16d. Specifically, as shown in FIGS. 1 and 2, the optical branching coupler 15 is constituted by, for example, a known optical branching coupler, is connected to the first optical transmission line 14, and is connected to the second optical fiber. The transmission lines 16a to 16d are also connected, and the optical signal received by the first optical transmission line 14 is equally branched to the second optical transmission lines 16a to 16d.

  The second optical transmission lines 16a to 16d are optical transmission lines that transmit a plurality of optical signals branched by the optical branching coupler 15 to the optical connectors 17a to 17d, and all have the same line length.

  The optical connectors 17a to 17d are terminals that output optical signals transmitted through the second optical transmission lines 16a to 16d. Specifically, each of the optical connectors 17a to 17d is configured by, for example, a known male optical connector, and is connected to any one of the corresponding second optical transmission lines 16a to 16d. The optical input terminal 13, the first optical transmission line 14, the optical branching coupler 15, the second optical transmission lines 16a to 16d, and the optical connectors 17a to 17d are preferably integrated to eliminate variations in optical transmission loss. Good.

(Configuration-housing)
The housing 20 is a protective means that arranges optical connectors 17a to 17d and a detachable connector and protects the circuit board 30 from the outside. Specifically, as shown in FIGS. 1 and 2, the housing 20 is formed by deforming a metal plate, for example, and has a substantially box shape with one side surface (for example, the upper surface of the housing 20 or the like) open. A base portion 21 and a cover portion 22 that substantially covers the base portion 21 from its open surface side are provided. Further, the cover portion 22 is fixed to the base portion 21 with a fixture or the like.

  Further, a terminal hole 23 is formed on the front side surface of the base portion 21, and an output terminal 35 that is a coaxial connector of a circuit board 30 to be described later is connected to the outside of the housing 20 through the terminal hole 23. Is exposed. Thereby, the transmission line 40 which is a coaxial cable can be easily connected to the output terminal 35.

  Further, the cover portion 22 is provided with optical connectors 24a to 24d in a line. The optical connectors 24 a to 24 d are optical connector terminals that receive an input of an optical signal transmitted from the optical transmission line system 10. Specifically, as shown in FIG. 1, the optical connectors 24 a to 24 d are configured by, for example, known female optical connectors, and are arranged in a state exposed to the outside of the housing 20, and the cover portion 22. It is fixed with a fixture or the like. Each of the optical connectors 24a to 24d is detachably connected to any one of the optical connectors 17a to 17d of the corresponding optical transmission line system 10, and the first photoelectric conversion of the circuit board 30 to be described later. Among the circuits 31a to 31d, the corresponding one of the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d and an opening (not shown) provided in the cover unit 22 are provided. It is connected. The optical connectors 24a to 24d and the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d may be connected via an optical fiber, or the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d. The optical connectors 24a to 24d may be an integral part.

(Configuration-circuit board)
The circuit board 30 is a board on which an electric circuit (not shown) for realizing various functions of the optical receiver 1 is mounted. Specifically, the circuit board 30 is accommodated in the housing 20 and is fixed to the base portion 21 by a fixture, a fitting structure, or the like. As shown in FIG. 2, the circuit board 30 is mounted with known electronic components similar to those used in a conventional optical receiver, and the first photoelectric conversion circuits 31a to 4th. A photoelectric conversion circuit 31d, first transmission lines 32a to 32d, an electric signal synthesis unit 33, a second transmission line 34, and an output terminal 35 are mounted.

  The first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d are photoelectric conversion means that photoelectrically convert an optical signal output from any one of the corresponding optical connectors 24a to 24d into an electrical signal. Specifically, the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d are configured by, for example, a known photoelectric conversion circuit, and can be driven without a power supply including a PD, It is used in a non-bias mode (for example, a solar cell mode) in which no reverse voltage is applied so that photoelectric conversion can be performed without applying a reverse voltage. For example, the anode and cathode of the PD can be short-circuited with a coil to circulate the DC component, and connected to the output terminal in series with the PD via a capacitor, so that a photoelectric conversion can be performed without bias and a television signal can be output from the output terminal. It consists of a circuit.

  Since the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d need to have the same photoelectric conversion characteristics, they are configured with the same circuit configuration and output electrical signals. The first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d are disposed on the circuit board 30 and connected to the circuit board 30 by soldering. As shown in FIG. 2, each of the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d is electrically connected to any one of the corresponding first transmission lines 32a to 32d. Yes. As a result, the first photoelectric conversion circuit 31 a to the fourth photoelectric conversion circuit 31 d are connected in parallel between the optical branching coupler 15 and the electric signal combining unit 33.

  The first transmission lines 32 a to 32 d are transmission lines that transmit the electric signals photoelectrically converted by the first photoelectric conversion circuit 31 a to the fourth photoelectric conversion circuit 31 d to the electric signal combining unit 33. Specifically, the first transmission lines 32a to 32d are mounted on the circuit board 30 as known printed wiring (the same applies to the second transmission line 34). The first transmission lines 32a to 32d have the same line length.

  The electric signal combining unit 33 is an electric signal combining unit that combines a plurality of electric signals transmitted through the first transmission lines 32a to 32d. Specifically, the electric signal synthesizer 33 is composed of, for example, a known mixed circuit, is disposed on the circuit board 30, and is connected to the circuit board 30 by soldering. In addition, as shown in FIG. 2, the electrical signal synthesis unit 33 is electrically connected to the first transmission lines 32 a to 32 d and is also electrically connected to the second transmission line 34.

  The second transmission line 34 is a transmission line that transmits the electrical signal synthesized by the electrical signal synthesis unit 33 to the output terminal 35.

  The output terminal 35 is a terminal that outputs an electrical signal transmitted through the second transmission line 34 to the television receiver via the transmission line 40. Specifically, the output terminal 35 is a coaxial connector.

(Configuration-configuration of second optical transmission line and first transmission line)
Here, in the configurations of the second optical transmission lines 16a to 16d and the first transmission lines 32a to 32d, the following devices are applied.

  As described above, the first photoelectric conversion circuit 31 a to the fourth photoelectric conversion circuit 31 d are connected in parallel between the optical branching coupler 15 and the electric signal combining unit 33. Here, for example, the transmission distance (for example, the first photoelectric conversion circuit 31a) corresponding to each of the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d from the optical branching coupler 15 to the electric signal combining unit 33. In the case where the length of the second optical transmission line 16a is different from the total length of the first transmission line 32a), the phase of the electric signal input to the electric signal combining unit 33 May cause a drop in the level of the electrical signal synthesized by the electrical signal synthesis unit 33, and the TV signal included in the electrical signal may not be correctly transmitted to the television receiver. Therefore, in the first embodiment, the second optical transmission lines 16a to 16d and the first transmission lines 32a to 32d are phase-adjusted for suppressing a phase shift of the electric signal input to the electric signal combining unit 33. It is configured as a means.

  Specifically, as shown in FIG. 2, the configurations of the second optical transmission lines 16 a to 16 d are formed so as to have substantially the same length. Thereby, the phase of the optical signal input from the optical branching coupler 15 to the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d via the second optical transmission lines 16a to 16d can be tuned. Further, the optical receiver 1 may not include a special component for tuning the phases of these optical signals.

  Further, as shown in FIG. 2, the first transmission lines 32a to 32d are formed so that the lengths of the first transmission lines 32a to 32d on the printed circuit board are substantially equal to each other. ing. For example, when the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d are arranged in a horizontal row as shown in FIG. 1 and the electric signal synthesis unit 33 on the circuit board is provided near the center of the board, Temporarily, the 2nd photoelectric conversion circuit 31b and the electric signal synthetic | combination part 33 are linearly connected by the 1st transmission line 32b, and the 3rd photoelectric conversion circuit 31c and the electric signal synthetic | combination part 33 are the 1st transmission line. When connected linearly by 32c, the first transmission line 32a becomes a wiring pattern that goes around the outside of the wiring of the first transmission line 32b, and the first transmission line 32d becomes the wiring pattern of the first transmission line 32c. Since the wiring pattern goes around the outside of the wiring, the lengths of the first transmission lines 32a and 32d are longer than those of the first transmission lines 32b and 32c. Therefore, in the present embodiment, a plurality of first transmission lines 32b and 32c are folded back so that the line lengths from the first transmission lines 32a to 32d to the electric signal combining unit 33 are substantially the same. It is formed as a detoured line pattern. Thereby, the phase of the electrical signal input to the electrical signal combining unit 33 from the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d via the first transmission lines 32a to 32d can be tuned. Further, the optical receiver 1 may not include a special component for tuning the phase of these electric signals.

(Operation of optical receiver)
Next, the operation of the optical receiver 1 configured as described above will be described.

  First, an optical signal including a television signal transmitted from an optical transmitter on the CATV center side is input to the optical input terminal 13 via the optical transmission path 11 and the optical output terminal 12. Next, the optical signal input to the optical input terminal 13 is output to the optical branching coupler 15 via the first optical transmission line 14.

  Next, the optical signal input to the optical branching coupler 15 is branched into four optical signals by the optical branching coupler 15, and the four branched optical signals are routed through the second optical transmission lines 16a to 16d. Are output to the corresponding optical connectors 17a to 17d, respectively. For example, one of the optical signals branched by the optical branching coupler 15 is output to the optical connector 17a via the second optical transmission line 16a. In this case, since the second optical transmission lines 16a to 16d are formed with substantially the same length, the phases of the four optical signals output to the optical connectors 17a to 17d are tuned.

  Next, each optical signal input to the optical connectors 17a to 17d is sent to any one of the corresponding first photoelectric conversion circuit 31a to fourth photoelectric conversion circuit 31d via any one of the corresponding optical connectors 24a to 24d. Is output as one. For example, an optical signal input to the optical connector 17a is output to the first photoelectric conversion circuit 31a via the optical connector 24a.

  Next, each optical signal input to the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d is transmitted by any one of the corresponding first photoelectric conversion circuit 31a to fourth photoelectric conversion circuit 31d. It is photoelectrically converted into an electrical signal. Since the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d have the same circuit configuration, they are converted into electric signals with the same photoelectric conversion characteristics. The photoelectrically converted electric signals are output to the electric signal synthesizer 33 via the corresponding first transmission lines 32a to 32d. For example, when a predetermined amount of light energy is incident on the first photoelectric conversion circuit 31a to which no reverse voltage is applied from the optical branching coupler 15 via the optical connector 24a, this light energy is absorbed by the depletion layer. Then, generation and drift of conduction electrons and holes are performed, so that an electromotive force proportional to the light intensity is generated. And a television signal flows into the electric signal synthetic | combination part 33 via the 1st transmission line 32a by the electromotive force which generate | occur | produced in the 1st photoelectric conversion circuit 31a. In this case, since the first transmission lines 32a to 32d are formed with substantially the same length, the phases of the four electric signals output to the electric signal combining unit 33 are tuned.

  Subsequently, the four electrical signals input to the electrical signal synthesis unit 33 are synthesized by the electrical signal synthesis unit 33. The synthesized electrical signal is output to the television receiver via the second transmission line 34 and the output terminal 35.

  By such an operation, the level of the optical signal transmitted from the optical transmitter can be made higher than in the case of a single photoelectric conversion circuit (specifically, in the case of a single photoelectric conversion circuit) In contrast, in the case of the 4-branch of the first embodiment, the level of the optical signal can be increased by about 6 dB), and a high-level electric signal is output from the output terminal 35 to the television receiver while suppressing the influence of distortion. (Specifically, the level of the electric signal can be increased by about 4 times compared to the case of a single photoelectric conversion circuit).

(effect)
As described above, according to the first embodiment, an optical signal level higher than that of an optical receiver including a conventional single photoelectric conversion unit is input to the optical receiver, and the optical signal is branched into a plurality of transmission paths. Each photoelectric conversion means is configured to output each of the electrical signals by combining each electrical signal after suppressing the photoelectric signal level to a predetermined level that does not cause distortion, and increasing the signal level. It is possible to output a signal at a signal level higher than that of an electrical signal output by the photoelectric conversion element. Further, in order to prevent the phase shift of each electrical signal, the phase adjusting means is formed to have substantially the same length as the second optical transmission lines 16a to 16d formed so as to have substantially the same length. Since the first transmission lines 32a to 32d are used, the electricity input from the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d to the electric signal combining unit 33 via the first transmission lines 32a to 32d. The phase of the signal can be tuned, and the TV signal included in the electrical signal synthesized by the electrical signal synthesis unit 33 can be correctly transmitted to the television receiver at a high level. Moreover, it is not necessary to provide special parts for tuning the phases of these electric signals.

  In addition, since the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d are connected in parallel to each other, compared to the case where the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d are connected in series to each other. The level of current flowing through the circuit board 30 can be increased.

[Modifications to Embodiment]
Although the embodiments of the present invention have been described above, the specific configuration and means of the present invention can be arbitrarily modified and improved within the scope of the technical idea of each invention described in the claims. Can do. 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 the phase adjusting unit cannot accurately tune the phases of the plurality of electric signals output to the electric signal combining unit 33 via the first transmission lines 32a to 32d, the plurality of electric signals When the signal phase tuning can be achieved in the same way as in the prior art by a technique different from the prior art, the problem of the present invention is solved.

(Installation of optical receiver)
In Embodiment 1 described above, the optical receiver is described as being installed outside the dwelling unit. However, for example, the optical receiver may be installed indoors in the dwelling unit.

(About optical transmission line system)
In the first embodiment, it has been described that the optical transmission line system 10 is arranged outside the housing 20 as shown in FIG. It may be housed inside. Specifically, among the constituent elements of the optical transmission line system 10, constituent elements other than the first optical transmission line 14 may be accommodated in the housing 20.

(About the usage state of the photoelectric conversion circuit)
In Embodiment 1 described above, the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d have been described as being used in the no-bias mode without application of a reverse voltage. It may be used with a reverse voltage applied.

(About the number of photoelectric conversion circuits)
In Embodiment 1 described above, the circuit board 30 is described as including the first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d. However, the present invention is not limited to this. For example, the circuit board 30 may include a number of photoelectric conversion circuits corresponding to the level of the optical signal transmitted from the optical transmitter. Specifically, in the first embodiment, when the level of the optical signal transmitted from the optical transmitter is lower than a predetermined level, the circuit board 30 includes two or three photoelectric conversion circuits. (It is preferable to reduce the number of photoelectric conversion circuits in consideration of the suppression of the level loss that occurs when the optical signal is branched by the optical branching coupler 15 or mixed by the electric signal combining unit 33). Alternatively, when the level of the optical signal transmitted from the optical transmitter is higher than a predetermined level, the circuit board 30 may include four or more photoelectric conversion circuits. In these cases, the numbers of the second optical transmission line and the first transmission line are also changed according to the number of photoelectric conversion circuits.

(About phase adjustment means)
In the first embodiment, it has been described that the first transmission lines 32a to 32d are folded back in order to make all of the first transmission lines 32a to 32d have the same line length. The first photoelectric conversion circuit 31a to the fourth photoelectric conversion circuit 31d as shown in FIG. 1 are not arranged in a single line on the left and right, but the first photoelectric conversion circuit 31a and the fourth photoelectric conversion circuit that form wiring patterns on the outside. The conversion circuit 31d may be arranged closer to the electric signal synthesis unit 33 than the second photoelectric conversion circuit 31b or the third photoelectric conversion circuit 31c. The first transmission lines 32b and 32c may all be configured to have the same line length as a straight line pattern.
In addition, as a configuration in which a plurality of photoelectric conversion circuits are arranged around the electric signal synthesis unit 33, the first transmission lines 32a to 32d may all have the same line length.

(About phase adjustment means)
Moreover, in the said Embodiment 1, although the structure which makes all the 1st transmission lines 32a-32d the same line length and tunes a phase was shown, not only this but on 1st transmission lines 32a-32d Alternatively, a known phase adjuster may be inserted to adjust the circuit so that the mutual phases are tuned. For example, a phase adjuster may be inserted into the first transmission lines 32b and 32c in which the line pattern is shortened so that the phases of the electrical signals of the first transmission lines 32a and 32d having a long line length are matched. When the phase is tuned by inserting a phase adjuster, even if the line lengths of all the wiring patterns are different, adjustment can be made by appropriately inserting the phase adjuster.
[Appendix]
The optical receiver of Supplementary Note 1 is an optical receiver that receives an optical signal and converts it into an electrical signal, branches the optical signal into a plurality of optical signals, and transmits the branched optical signals to a plurality of optical transmissions. Optical signal branching means for outputting via a path, and a plurality of photoelectric conversion means connected to the optical signal branching means via the plurality of optical transmission paths, wherein the light branched by the optical signal branching means A plurality of photoelectric conversion means for converting a signal into an electrical signal; and an electric signal combining means connected to each of the plurality of photoelectric conversion means via a plurality of transmission lines, wherein the conversion is performed by the plurality of photoelectric conversion means. An electric signal combining unit configured to combine the plurality of electric signals; and when the plurality of electric signals are combined by the electric signal combining unit, the phases of the plurality of electric signals are synchronized. The phase of at least a part of the optical signal or the plurality And a, a phase adjusting means for adjusting at least part of the phase of the electrical signal.
Further, the optical receiver according to appendix 2 is the optical receiver according to appendix 1, wherein the phase adjusting means includes the plurality of transmission lines formed to have substantially the same length.
Further, the optical receiver according to appendix 3 is the optical receiver according to appendix 1 or 2, wherein the phase adjusting means includes the plurality of optical transmission lines formed to have substantially the same length.
Further, the optical receiver according to appendix 4 is the optical receiver according to any one of appendices 1 to 3, wherein the phase adjusting means includes at least a part of the plurality of electrical signals among the plurality of transmission lines. Including a phase adjuster for adjusting the phase of the electrical signal transmitted through the transmission line.
Further, the optical receiver according to appendix 5 is the optical receiver according to any one of appendices 1 to 4, wherein the plurality of photoelectric conversion means are connected in parallel to each other.
[Advantageous effects]
According to the optical receiver described in appendix 1, an optical signal is branched into a plurality of optical transmission lines, then converted into an electrical signal by a plurality of photoelectric conversion means, and a plurality of electrical signals are synthesized by an electrical signal synthesis means. The phase of at least a part of the plurality of optical signals or the phase of at least a part of the plurality of electrical signals so that the phases of the plurality of electrical signals are tuned when being configured by the electrical signal synthesis means Since the phase adjustment means for adjusting the phase of the electric signal is provided, the phase shift of the plurality of electric signals input to the electric signal synthesizing means can be suppressed, and the level of the electric signal synthesized by the electric signal synthesizing means is predetermined. Can be maintained at a level. Therefore, the TV signal included in the electric signal can be transmitted to the television receiver while suppressing the influence of distortion.
Further, according to the optical receiver described in appendix 2, the phase adjusting unit includes a plurality of transmission lines formed to have substantially the same length, and thus a plurality of electric signals input to the electric signal combining unit. Therefore, it is not necessary to provide a special part for suppressing the phase shift of the optical receiver, and the manufacturing cost of the optical receiver can be suppressed.
Further, according to the optical receiver described in appendix 3, the phase adjusting unit includes a plurality of optical transmission paths formed to have substantially the same length, so that the optical signal input to each photoelectric conversion unit It is not necessary to provide special parts for suppressing the phase shift, and the manufacturing cost of the optical receiver can be suppressed.
Further, according to the optical receiver described in Appendix 4, the phase adjusting unit adjusts the phase of the electrical signal transmitted by the transmission line that transmits at least a part of the plurality of electrical signals among the plurality of transmission lines. Since the phase adjuster is included, the phase shift of the electric signal output to the electric signal synthesizing means via the plurality of transmission lines can be accurately suppressed as compared with the case where the phase adjusting means is formed by a plurality of transmission lines. And the level of the electric signal synthesized by the electric signal synthesizing means can be stably maintained at a predetermined level.
Further, according to the optical receiver described in Appendix 5, since the plurality of photoelectric conversion means are connected to each other in parallel, the plurality of photoelectric conversion means are built in the optical receiver as compared with the case where the plurality of photoelectric conversion means are connected to each other in series. The level of current flowing through the circuit board can be increased.

DESCRIPTION OF SYMBOLS 1, Optical receiver 10 Optical transmission line system 11 Optical transmission line 12 Optical output terminal 13 Optical input terminal 14 1st optical transmission line 15 Optical branching coupler 16a, 16b, 16c, 16d 2nd optical transmission line 17a, 17b, 17c, 17d, 24a, 24b, 24c, 24d Optical connector 20 Housing 21 Base part 22 Cover part 23 Terminal hole 30 Circuit board 31a First photoelectric conversion circuit 31b Second photoelectric conversion circuit 31c Third photoelectric conversion circuit 31d 4th photoelectric conversion circuit 32a, 32b, 32c, 32d 1st transmission line 33 Electric signal synthetic | combination part 34 2nd transmission line 35 Output terminal 40 Transmission line

Claims (3)

An optical receiver for CATV that receives an optical signal and converts it into an electrical signal,
Optical signal branching means for branching the optical signal into a plurality of optical signals, and outputting the branched optical signals via a plurality of optical transmission lines;
A plurality of photoelectric conversion means connected to the optical signal branching means via the plurality of optical transmission lines, wherein the photoelectric conversion means converts the optical signal branched by the optical signal branching means into an electrical signal. When,
Electrical signal synthesis means connected to each of the plurality of photoelectric conversion means via a plurality of transmission lines, the electrical signal synthesis means for synthesizing a plurality of electrical signals converted by the plurality of photoelectric conversion means; ,
At least a part of the phases of the plurality of optical signals, or the plurality of electrical signals so that the phases of the plurality of electrical signals are synchronized when the plurality of electrical signals are synthesized by the electrical signal synthesizing unit. and a phase adjusting means for adjusting at least part of the phase,
The phase adjusting means includes the plurality of optical transmission lines and the plurality of transmission lines,
The plurality of optical transmission lines are formed to have substantially the same length, and the optical signal branching unit and the plurality of photoelectric conversion units are connected by a non-shortest path,
The plurality of transmission lines are formed to have substantially the same length as each other, and connect the plurality of photoelectric conversion means and the electric signal combining means by a non-shortest path,
Only the optical signal as signal light is input to the optical signal branching means and branched to the plurality of optical signals without polarization, and the plurality of photoelectric conversion means without polarization of the branched optical signals Is converted into the plurality of electrical signals, and the plurality of converted electrical signals are synthesized by the electrical signal synthesis means and output.
Optical receiver. Each of the plurality of photoelectric conversion means can be driven without power supply.
The optical receiver according to claim 1. The plurality of photoelectric conversion means are connected in parallel to each other.
The optical receiver according to claim 1 or 2.

Images