JPH0110028Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a broadcast signal switching device for supplying a converted signal obtained by converting the frequency of a satellite broadcast signal by a converter and a general television signal to an indoor unit through a single transmission line.

Conventionally, indoor units include the following: In other words, a demodulator or converter converts the converted signal from the converter into a signal that can be received by the television receiver.
The signal is processed by a processing circuit such as an RF converter, and the signal from this processing circuit and a general television amplified signal amplified by a booster are supplied to one receiver using a changeover switch. Generally, as the name suggests, such an indoor unit is placed indoors at home, and the converter and booster are attached to a pole or the like that supports the antenna outdoors. Therefore, two long coaxial cables are required to connect the indoor unit to the converter or booster, which is uneconomical and requires troublesome wiring.

The object of this invention is to provide a broadcast signal switching device that can transmit an amplified signal from a booster and a converted signal from a converter to an indoor unit using a single coaxial cable. Therefore, this idea is 1
The amplified signal from the booster and the converted signal from the converter are switched and supplied to the main coaxial cable.In particular, this switching is used to supply the operating current to the booster or converter by superimposing it on the coaxial cable. In contrast, AC current is supplied to the second booster as the operating current in consideration of economic efficiency.
In order to obtain clear image quality, the converter is supplied with a direct current as an operating current, and detects whether the current superimposed on the coaxial cable is alternating current or direct current.

Hereinafter, this invention will be explained in detail based on one embodiment shown in the drawings. In the figure, reference numeral 2 denotes a general broadcast receiving antenna, and the general broadcast signal received by this antenna is amplified by a booster 4. Note that the booster 4 includes an internal rectifier circuit that converts the alternating current supplied to the output side into direct current and supplies the direct current to each component. Reference numeral 6 denotes a satellite broadcast receiving antenna, and the satellite broadcast signal received by this antenna is frequency-converted by a converter 8. This converter 8 operates by taking in the DC current supplied to its output side. The amplified signal from booster 4 and the converted signal from converter 8 are supplied to broadcast signal switching device 10 according to this invention.

Broadcast signal switching device 10 includes a relay 16 that includes relay contacts 12 and a relay drive circuit 14 .
A contact 12a of the relay contact 112 is connected to the output side of the converter 8, and a contact 12b of the relay contact 12 is connected to the output side of the converter 8.
is connected to the output side of the booster 4. The contact piece 12bc of the relay contact 12 is connected to the contact 12a while no current is flowing through the relay drive circuit 14,
While current is flowing through the relay drive circuit 14, it is connected to the contact 12b. A series circuit of a high frequency blocking coil 18, a diode 20, a current limiting resistor 22, and a relay drive circuit 14 is connected between the contact piece 12c and the reference potential point. diode 2
0 is connected in a direction that is reverse biased when a positive current is supplied to the contact piece 12c, that is, the cathode is connected to the high frequency blocking coil 18 side, and the arc is connected to the current limiting resistor 22 side. . Note that 24 is a smoothing capacitor.

The contact piece 12c is connected to a contact 30a of a changeover switch 30 in the indoor unit 28 via one coaxial cable 26. The contact 30b of the changeover switch 30 is connected to the input side of the demodulator 34 via the superimposition circuit 32, and is also connected to the input side of the demodulator 34 via the superposition circuit 32.
It is connected to a DC power supply 36 via. In addition,
The DC power supply 36 supplies a positive DC current, and also supplies operating current to the demodulator 34 and the RF converter 38. The output side of the demodulator 34 is connected to the input side of the RF converter 38, and the output side of the RF converter 38 is connected to the contact 40 of the changeover switch 40.
It is connected to b.

The contact 30c of the changeover switch 30 is connected to the superimposition circuit 42.
It is connected to the contact 40c of the changeover switch 40 via the switch 40, and is also connected to the AC power source 44 via the superimposition circuit 42. A contact 40a of the changeover switch 40 is connected to a television receiver 46. The changeover switches 30 and 40 are configured to interlock, and when the contact 30a of the changeover switch 30 is connected to the contact 30b, the contact 40a of the changeover switch 40 is connected to the contact 40b.
In addition, the contact 30a of the changeover switch 30 is
When connected to c, the contact 40 of the changeover switch 40
a is connected to contact 40c.

When the television receiver 46 receives a satellite broadcast signal using the signal switching device 10 configured as described above, the contacts 3 of the changeover switches 30 and 40
What is necessary is to switch 0a and 40a to the contacts 30b and 40b. As a result, a positive DC current is supplied from the DC power supply 36 to the signal switching device 10 via the superimposing circuit 32, the changeover switch 30, and the coaxial cable 26. At this time, the diode 20 is reverse biased, so no current flows through the relay drive circuit 14, and the contact piece 12c of the relay contact 12 remains connected to the contact 12a. Therefore, the positive DC current is supplied to converter 8, and converter 8 operates. As a result, the satellite broadcast signal is frequency-converted, and the converted signal is supplied to the demodulator 32 via the coaxial cable 26, the changeover switch 30, and the superimposition circuit 32, processed by the demodulator 34 and the RF converter 38, and then sent to the changeover switch. 40 to a television receiver 46.

Further, when receiving a general broadcast signal, the contacts 30a and 40a of the changeover switches 30 and 40 may be switched to the contacts 30c and 40c, respectively. As a result, the alternating current is transferred from the alternating current power source 44 to the superimposing circuit 3.
2. The signal is supplied to the signal switching device 10 via the changeover switch 30 and the coaxial cable 26. At this time, the alternating current is converted to direct current by the diode 20 and the smoothing capacitor 24, and this direct current is converted to the direct current by the relay drive circuit 14.
flows to As a result, contact piece 12 of the relay contact
c switches from the contact 12a to the contact 12b, an alternating current flows to the booster 4, and the booster 4 operates. The booster 4 amplifies a general television broadcast signal, and the amplified signal is sent to a television receiver 46 via a relay contact 12, a coaxial cable 26, a changeover switch 30, a superimposition circuit 42, and a changeover switch 40.
is supplied to

In the signal switching device 10 according to this invention, the current superimposed on the coaxial cable 26 is split between alternating current and direct current.
By utilizing this fact, the relay 16 is operated only when an alternating current is superimposed on the coaxial cable, and the coaxial cable 26 connected to the converter 8 side is connected to the booster 4 when a direct current is superimposed on the coaxial cable. Since the signals are switched, the general broadcast signal and the satellite broadcast signal can be transmitted to the indoor unit 28 using only one coaxial cable 26. Therefore, wiring becomes simple and economical.

Note that the indoor unit 28 shown in the above embodiment
Then, even when the amplified signal from the booster 4 is being supplied to the television receiver 46, the demodulator 34,
The RF converter 38 will operate, but a new changeover switch is provided between the connection point 48 shown in the figure and the DC power source 36, and the changeover switch that operates in conjunction with the changeover switches 30 and 40 is connected to the contact piece 30 of the changeover switch 30 and 40.
The DC power source 36 and the connection point 48 may be connected only when the contacts 30b, 40b are connected to the contacts 30b, 40b. Furthermore, although the DC power supply 36 is shown as one that supplies positive DC current, it may also be one that supplies negative DC current. However, in that case, the directionality of the diode 20 must be reversed from that shown in the figure.

[Brief explanation of drawings]

The figure is a block diagram of a broadcast receiving device using the broadcast signal switching device according to this invention. 4...Booster, 8...Converter, 12...
Relay contact, 12a...first contact, 12b...second contact, 12c...contact piece, 14...relay drive circuit, 20...diode, 26...coaxial cable (signal transmission path).

Claims (1)

[Scope of utility model registration request] The contact piece of the relay contact is connected to the other end of the signal transmission path, where the AC current for the booster that amplifies the general television signal and the DC current for the converter that converts the frequency of the satellite broadcasting signal are switched from one end. , a first contact of the relay contact is connected to the output side of the converter, a second contact of the relay contact is connected to the output side of the booster, and the contact piece is connected to the second contact only while current is flowing. Broadcasting signal switching comprising connecting a series circuit of a relay drive circuit and a diode to be connected between the signal transmission path and a reference potential point, and connecting the diode in a direction that is reverse biased by the direct current. Device.