Distributor and broadcast signal receiving system using the same

A distributor arranged between a tuner module and an antenna, the tuner module including a first input portion and a second input portion for inputting a satellite broadcast signal transmitted from an artificial satellite and a ground broadcast signal transmitted from a ground base station respectively, and the antenna receiving either one of the broadcast signals. The distributor includes a first connector portion connected to the antenna; a second connector portion connected to the first input portion; a third connector portion connected to the second input portion; and a junction connecting portion distributing the signal inputted to the first connector portion to the second and the third connector portions. A drive voltage of the antenna inputted from the first input portion is outputted to the antenna. The voltage outputted to the antenna is fed back to the second input portion through the junction connecting portion and the third connector portion.

BACKGROUND OF THE INVENTION

The present invention relates to a distributor for distributing a signal received by an antenna to a tuner module having a plurality of input portions, further in details, relates to a distributor preferably used in a case of connecting a single antenna to a tuner module for detecting connection or the antenna by feeding back a drive voltage of the antenna inputted from one input portion to other input portion and a broadcast signal receiving system using the same.

In recent years, there is proposed a satellite radio broadcast by transmitting to broadcast a signal including vocal information from an artificial satellite orbiting an earth orbit. Currently, in the United States, there is proposed such a satellite radio broadcast by XM Satellite Radio Corporation. In the satellite radio broadcast, a signal transmitted from an artificial satellite can be received in a wide area on the earth and therefore, attention is attracted thereto since the satellite radio broadcast is preferable not only for use of receiving and herring the broadcast by installing a receiver at a fixed location of a general household or the like but also for use of receiving and herring the broadcast by mounting a receiver to a moving body (for example, a vehicle body) or, for example, an automobile or the like.

In a vehicle-mounted receiving system for receiving satellite radio broadcast, both of satellite radio broadcast and ground radio broadcast which has conventionally been used widely are received by a single tuner module for the purpose of reducing a number of parts to achieve low cost.

According to such a vehicle-mounted receiving system, as shown inFIG. 5, a tuner module101having a first input portion110connected to a satellite wave antenna for receiving satellite radio broadcast, a second input portion111connected to a ground wave antenna for receiving ground radio broadcast and input/output terminals112connected to respective portions on a side of the receiver100are provided in a receiver100which is mounted to a vehicle. Further, the tuner module101includes an antenna detecting circuit113for detecting that the respective antennas are connected by inputting a drive voltage of an antenna120inputted from the first input portion110is fed back through the antenna to input from the second input portion111.

According to the related tuner module101, in a state that a satellite wave antenna and a ground wave antenna are respectively connected to the first input portion110and the second input portion111, a drive voltage (drive power) inputted from the input/output terminals112is outputted to the respective antennas Via the first input portion110to be fed back from the respective antennas to the second input portion111. Further, the antenna detecting circuit113detects that the respective antennas are normally connected, thereby the tuner module101is normally operated under the state (for example, see JP-A-2003-151377).

The related tuner module101is normally operated as described above when the satellite wave antenna and the ground wave antenna are respectively connected to the tuner module101in a state that the antenna module having both of the satellite wave antenna and the ground wave antenna is connected to the tuner module101, for example, as shown inFIG. 5. However, when a single antenna for receiving only either one of a satellite wave or a ground wave is connected to the tuner module101, a voltage is not applied to a side of the antenna detecting circuit113and therefore, connection of the antenna is not detected and the tuner module101cannot be operated normally. When a single antenna is used, there is a case in which a tuner module in correspondence with the single antenna needs to use to bring about an increase in fabrication cost.

SUMMARY OF THE INVENTION

Hence, the invention has been carried out in view of the above-described actual situation and it is an object thereof to provide a distributor capable of normally operating a tuner module even when a single antenna is connected to the tuner module including two routes of input portions and constituted by a structure of detecting connection of the antenna by feeding back a drive voltage at the respective input portions and a broadcast signal receiving system using the same.

In order to achieve the above object, according to the present invention, there is provided a distributor arranged between a tuner module and an antenna, the tuner module including a first input portion for inputting one of a satellite broadcast signal transmitted from an artificial satellite and a ground broadcast signal transmitted from a ground base station and a second input portion for inputting other of the satellite broadcast signal and the ground broadcast signal, and the antenna receiving either one of the satellite broadcast signal and the ground broadcast signal, the distributor, comprising:

a first connector portion, connected to the antenna;

a second connector portion, connected to the first input portion;

a third connector portion, connected to the second input portion; and

a junction connecting portion, distributing the signal inputted to the first connector portion to the second and the third connector portions,

wherein a drive voltage of the antenna inputted from the first input portion through the second connector portion is supplied to the antenna through the first connector portion; and

wherein the voltage outputted to the antenna is fed back to the second input portion through the junction connecting portion and the third connector portion.

According to the present invention, there is also provided a distributor arranged between a tuner module and an antenna, the tuner module including a first input portion for inputting one of a satellite broadcast signal transmitted from an artificial satellite and a ground broadcast signal transmitted from a ground base station and a second input portion for inputting other of the satellite broadcast signal and the ground broadcast signal, and the antenna receiving either one of the satellite broadcast signal and the ground broadcast signal, the distributor, comprising:

a first connector portion, connected to the antenna;

a second connector portion, connected to the first input portion;

a third connector portion, connected to the second input portion;

a junction connecting portion, distributing the signal inputted to the first connector portion to the second and the third connector portions; and

a signal level compensating portion, compensating a signal loss at the junction connecting portion, and provided between the first connector portion and the junction connecting portion.

According to the present invention, there is also provided a broadcast signal receiving system, comprising;

a tuner module, including:a first input portion, inputting one of a satellite broadcast signal transmitted from an artificial satellite and a ground broadcast signal transmitted from a ground base station; anda second input portion, inputting other of the satellite broadcast signal and the ground broadcast signal;

an antenna, receiving either one of the satellite broadcast signal and the ground broadcast signal;

a distributor, arranged between the tuner module and the antenna, and including:a first connector portion, connected to the antenna;a second connector portion, connected to the first input portion;a third connector portion, connected to the second input portion;a junction connecting portion, distributing the signal inputted to the first connector portion to the second and the third connector portions; and

a signal level compensating portion, compensating a signal loss at the junction connecting portion, the signal level compensating portion being provided between the first connector portion and the junction connecting portion,

wherein the tuner module includes an antenna connection detector which detects whether the antenna is connected to the tuner module through the divider;

wherein a drive voltage of the antenna inputted from the second connector portion is supplied to the antenna; and

wherein the drive voltage supplied to the antenna is fed back to the second input portion through the junction connecting portion and the third connector portion so that the voltage is supplied to the antenna connection detector in the tuner module.

According to the distributor and the broadcast signal receiving system of the invention, the tuner module can normally be operated even when a single antenna is connected to the tuner module which needs two inputs. Thereby, the tuner module including two routes of the input portions can commonly be used for a case of connecting two antennas and a case of connecting a single antenna to be able to contribute to a reduction in a product cost.

Further, by providing the low noise amplifier before distributing the signal, the amplifier which has been needed to the two routes after distribution in the background art may be provided only to one route to be able to reduce cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A detailed explanation will be given of an embodiment of the invention in reference to the drawings as follows. In the following, an explanation will be given by exemplifying a receiving system10shown inFIG. 1as a receiving system having a distributor according to the invention. Further, although the receiving system10is used for a so-to-speak vehicle-mounted radio broadcast receiving system which is mounted on a vehicle of an automobile or the like, the invention is not limited to the vehicle-mounted radio broadcast receiving system. For example, this invention is applied to a mobile radio broadcast receiving apparatus.

As shown inFIG. 1, a receiving system1is arranged with a tuner module11having a first input portion12connected to a satellite wave antenna for receiving satellite radio broadcast, a second input portion13connected to a ground wave antenna for receiving ground radio broadcast, and a tuner module11having input/output terminals14connected to respective portions on a side of the receiver10mounted to a vehicle. Further, the tuner module11includes an antenna detecting circuit is for detecting that the respective antennas are connected by feeding back a drive voltage of the antenna inputted from the first input portion12via the second input portion13.

According to the tuner module11, in a state that the satellite wave antenna and the ground wave antenna are respectively connected to the first input portion12and the second input portion13, a drive voltage (drive power) inputted from the input/output terminals14is outputted to the respective antennas via the first input portion12and is fed back from the respective antennas via the second input portion13. Further, under the state, the antenna detecting circuit15detects that the respective antennas are normally connected and the tuner module15is normally operated by the drive voltage inputted from the second input portion13.

As shown inFIG. 1, when, for example, an antenna module20having only the satellite wave antenna is connected to the tuner module11, a signal distributor30according to the invention is arranged between the tuner module11and the antenna module20.

Further, although according to the embodiment, an explanation will be given by assuming a case in which the antenna module20is provided only with the satellite wave antenna, operation and effect similar to those in the following explanation are naturally achieved even in a case in which the antenna module20is provided only with the ground wave antenna.

As shown inFIG. 2, the distributor30includes a main body case31containing a voltage feedback circuit and a signal level compensating circuit, a first connector portion32connected to the antenna module20, a second connector portion33connected to the first input portion12of the tuner module11, and a third connector portion34connected to the second input portion13of the tuner module11. Further, a first signal cable35and a second signal cable36respectively connect intervals between the main body case31and the second connector portion33as well as the third connector portion34.

Next, an example of circuit configurations of the voltage feedback circuit and the signal level compensating circuit contained in the main body case31will be explained in reference toFIG. 3.

The distributor30includes a circuit in which the first to third connectors32,33,34are electrically connected by a junction connecting portion A as shown in, for example,FIG. 3. Further, a first capacitor40, a first attenuator41, a low noise amplifier (LNA)42, a second attenuator43, and a second capacitor44are arranged between the first connector32and the junction connecting portion A, in the order from a side of the first connector32. A terminal or the first capacitor40on a side of the first connector32is connected also to the junction connecting portion A via a first coil45and a second coil46. Further, LNA42is connected also to the junction connecting portion A via a third coil47and the second coil46.

According to the distributor30having the above-described circuit constitution, a signal outputted from the antenna module20is inputted to the first connector portion32. The inputted signal is outputted to the second connector portion33. Further, a signal level of a signal distributed at the junction connecting portion A is amplified so as to compensate about 3 dB (about ½ of input signal level) of an amount of a signal level loss in distributing the signal as well as a contact loss (in correspondence with about 1 dB) at the first to the third connector portions32,33,34by LNA42provided at a prestage of the junction connecting point A.

Further, the signal level may be amplified by compensating for cable loss by, for example, the cable connecting the interval between the main body case31and the antenna module20or the tuner module11in addition to the loss by shunting and distributing the signal. Further, when a sufficient amplifying characteristic can be ensured, other various amplifiers may be used instead of LNA42.

The LNA42is provided at the prestage of the junction connecting portion A and amplifies the signal before distributing the signal. Thereby, although amplifiers need to provide normally for respective two routes after distribution, LNA42may be provided only to one route and the cost can be reduced.

Further, a drive voltage inputted from the second connector portion33is distributed at the junction connecting portion A and is outputted to the antenna module20from the first connector portion32via the second coil46end the first coil45. Further, the drive voltage distributed by the junction connecting portion A is outputted to the third connector portion34. Further, a portion of the drive voltage distributed by the junction connecting portion A and outputted to the antenna module20is inputted to LNA42via the third coil47.

Since the distributor30has the circuit having the constitution shown inFIG. 3, the circuit serves as the distributing circuit electrically connected to the first connector portion32, the second connector portion33, and the third connector portion34as a whole, further, the distributor30serves also as a voltage return circuit for outputting the drive voltage inputted from the first input portion12via the second connector portion33and outputting the drive voltage to the second input portion13via the third connector portion34.

Therefore, even when a single antenna (antenna module20) is connected to a tuner module (tuner module11) which includes two routes of input portions and the detecting circuit for detecting connection of an antenna by feeding back a drive voltage at the respective input portions, the tuner module can normally be operated. Thereby, the tuner module having two routes of the input portions can commonly be used for a case of connecting two antennas and a case of connecting a single antenna to be able to contribute to a reduction in product cost.

Next, a second embodiment of a divider according to the invention will be explained below in reference toFIG. 4. Further, a circuit of the divider shown inFIG. 4is substantially similar to the circuit constitution shown inFIG. 3, also operation and effect achieved by the constitution are similar to those of the constitution shown inFIG. 3and therefore, in the following, only a point of difference from the circuit constitution shown inFIG. 3will be explained.

According to the second embodiment shown inFIG. 4, a third and a fourth capacitor50,51are arranged respectively between the second coil46and the junction connecting portion A as well as between the junction connecting portion A and the third connector portion34. Further, the second connector portion33and the third connector portion34are short-circuited via a switching diode52.

According to the distributor30of the second embodiment, the switching diode52serves as a so-to-speakbypass circuit, and when the drive voltage inputted from the first connector portion33is fed-back to the second connector portion34, a level of the voltage to be fed back can be variably changed.

Although the invention has been illustrated and described for the particular preferred embodiments, it is apparent to a person skilled in the art that various changes and modifications can be made on the basis of the teachings of the invention. It is apparent that such changes and modifications are within the spirit, scope, and intention of the invention as defined by the appended claims.

The present application is based on Japan Patent Application No. 2004-002938 filed on Jan. 8, 2004, the contents of which are incorporated herein for reference.