JP2572990B2 - Satellite broadcast receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to solve the following problems.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite broadcast receiving apparatus capable of receiving a satellite broadcast, and more particularly, to a television receiver which can be connected to an antenna for receiving a television broadcast. The present invention relates to a satellite broadcast receiving device.

(Prior Art) In a satellite broadcast receiving apparatus of this type, a satellite broadcast receiving antenna having an active portion that receives power for operating a device and operates to output a reception signal, A terminal device for transmitting power for use and receiving a received signal, a first input terminal connected to an active portion of the satellite broadcast receiving antenna, a second input terminal for connecting a television receiving antenna, and A first input terminal and an output terminal, and a second input terminal and an output terminal of the mixer, wherein the first input terminal and the output terminal are connected to the terminal device. In the structure in which the power for operating the device is passed to the input terminal and the reception signal is passed from the first and second input terminals to the output terminal, a power-free antenna is connected to the second input terminal. Connected As a result, when the second input terminal is short-circuited, an excessive current flows there, causing a voltage drop, making it impossible to receive satellite broadcasts and causing a problem of damaging the power supply unit in the terminal device. .

(Problems to be solved by the invention) Except for the above-mentioned conventional problems, the present invention can prevent an excessive current from flowing even when the second input terminal is short-circuited, and can normally receive satellite broadcasting. It is an object of the present invention to provide a satellite broadcast receiving apparatus capable of maintaining a state and preventing damage to a power supply unit in a terminal device.

 The configuration of the present invention is as follows.

(Means for Solving the Problems) The present invention employs the means described in the claims, and the operation thereof is as follows.

(Operation) The electric power for operating the equipment sent from the terminal device passes through the output terminal and the first input terminal of the mixer, reaches the active portion of the satellite broadcast receiving antenna, and operates. By the operation, the reception signal output from the active section reaches the terminal device via the first input terminal and the output terminal of the mixer. On the other hand, when a television receiving antenna with a power using device is connected to the second input terminal of the mixer, the power for operating the device is transmitted from the output terminal to the power using device of the TV receiving antenna via the second input terminal. , It works. By the operation, the received signal output from the power using device reaches the terminal device via the second input terminal and the output terminal of the mixer. On the other hand, when a power-free television receiving antenna is connected to the second input terminal and short-circuited there, a positive temperature coefficient thermistor interposed in a connection circuit between the output terminal and the second input terminal Increases the current flowing from the output terminal to the second input terminal.

(Embodiment) Drawings showing an embodiment of the present application will be described below. First
In the figure, 1 is a satellite broadcast receiving antenna, 3 is a mixer, 4 is a television receiving antenna with power-consuming equipment, 5 is a television receiving antenna without power, and these are generally installed outdoors. . On the other hand, 2 indicates a terminal device, which is generally installed indoors.

The satellite broadcast receiving antenna 1 is a well-known parabolic antenna, and includes a reflector 10, a converter 11, a primary radiator 12, and the like. The converter 11 is an active part of a satellite broadcast receiving antenna, operates by receiving electric power for operating a device, and outputs a received signal.

Next, in the terminal device 2, reference numeral 14 denotes a satellite broadcast receiving tuner, which has a power supply circuit for operating the device therein and can output the power for operating the device from a converter connection terminal 15 provided therein. It has become. In addition, it is configured to select a received signal coming into the terminal 15 from the satellite broadcast receiving antenna 1 and extract an audio signal and a video signal therefrom, and output them from the audio output terminal 16 and the video output terminal 17, respectively. Have been. 18
A well-known AV television receiver is provided with an audio input terminal 19, a video input terminal 20, a UHF antenna terminal 21, a VHF antenna terminal 22, and the like. Reference numeral 23 denotes a duplexer for splitting an intermediate frequency signal of a received signal of a satellite broadcast and UHF and VHF television signals. Reference numeral 24 denotes a known UV demultiplexer. Next, in the mixer 3, a first input terminal 26 is connected to the converter 11 of the satellite broadcast receiving antenna 1 using a transmission line 32, for example, a coaxial cable. 27 is the second input terminal,
An output terminal 28 is connected to the duplexer 23 of the terminal device 2 using a transmission line 33, for example, a coaxial cable. 29 is a connection circuit between the first input terminal 26 and the output terminal 28, 30 is the second input terminal
27 shows a connection circuit between the output terminal 28 and the output terminal 28. They pass electric power for operating the device from the output terminal 28 to the first and second input terminals 26 and 27, and connect the power to the first and second input terminals 26 and 27. The output signal is passed to the output terminal 28. 31 is the connection circuit
A positive-characteristic thermistor interposed at 30 keeps the current passing to the power using equipment normal, and when an excessive current due to short circuit flows to the connection circuit 30, its own resistance increases and the output terminal
It has the characteristic of limiting the current from 28 to the second input terminal 27 to a small value.

Next, in the television receiving antenna 4 with a power using device, 35 is an amplifier exemplified as a power using device, and has a VHF input terminal 36, a UHF input terminal 37, and an output terminal 38,
It is configured to operate by inputting power for operating the device, for example, 15 V DC from the output terminal 38. 39 is
A VHF antenna 40 is a UHF antenna, which is connected to the input terminals 36 and 37, respectively, as shown.

Next, as the TV antenna 5 which does not use power,
For example, there is a well-known VHF television receiving antenna.

In the above configuration, electric power for operating the device (for example, DC 15 V) is transmitted from the tuner 14 to the output terminal 28 of the mixer 3 via the duplexer 23 and the transmission line 33 as indicated by the dashed arrow. Can be The power is supplied to the first input terminal through the connection circuit 29.
26, and is sent to the converter 11 via the transmission line 32 from there. As a result, converter 11 operates. In this operating state, satellite broadcast radio waves arriving from a broadcast satellite are reflected by the reflector 10 and received by the primary radiator 12. The received signal is converted to an intermediate frequency by converter 11 and output. The output intermediate frequency signal of the received satellite broadcast signal is transmitted through the transmission line 32 to the mixer 3 as shown by the solid arrow.
To the first input terminal 26. Further, the signal is output from the output terminal 28 through the connection circuit 19 and reaches the duplexer 23 of the terminal device 2 through the transmission line 33. The above-mentioned signal reaches the terminal 15 of the tuner 14 from the duplexer 23. Then, an audio signal and a video signal are output from the tuner 14 from respective output terminals 16 and 17, and the signals reach the receiver 18.

Next, when it is desired to use the television receiving antenna 4 with the power-consuming equipment, the output terminal 38 of the amplifier 35 is connected to the second input terminal 27 of the mixer 3 by a transmission line 41, for example, a coaxial cable. In this connection state, the power for operating the device arriving at the output terminal 28 is supplied to the second circuit through the connection circuit 30.
Output from the input terminal 27. Its power is coaxial cable 41
, And is sent from the output terminal 38 to the amplifier 35. As a result, the amplifier 35 operates. As a result of the operation, the reception signal (television signal) received by the VHF antenna 39 or the UHF antenna 40 is amplified by the amplifier 35 and output from the output terminal 38. As shown by the dashed line arrow,
The signal reaches the second input terminal 27 of the mixer 3 via the transmission line 41. Further, the signal is output from the output terminal 28 via the connection circuit 30. The output signal reaches the branching filter 23 of the terminal device 2 via the transmission line 33. Further, the above signal is sent from the duplexer 23 to the television receiver 18 via the UV duplexer 24.

On the other hand, when the power-free television receiving antenna 5 is used, the antenna 5 is connected to the second input terminal 27 of the mixer 3 using a transmission line 42 such as a coaxial cable. In this state, generally, the second input terminal 27 of the mixer 3 is short-circuited (directly) to the power for operating the device via the internal circuit of the antenna 5. However, mixer 3
Since the positive characteristic thermistor 31 is interposed in the connection circuit 30, the thermistor 31 generates heat when an excessive current due to the short circuit flows therethrough, and its resistance value becomes extremely high.
As a result, the current of the device operating power flowing through the connection circuit 30 is limited to a small value. Therefore, the voltage value of the electrons for operating the device at the output terminal 28 does not drop, and the operating state of the converter 11 by supplying the power to the converter 11 as described above is maintained normally. In this state, the television reception signal received by the antenna 5 reaches the second input terminal 27 of the mixer 3 via the transmission line 42, and is output from the output terminal 28 via the connection circuit 30. The signal is transmitted to the television receiver 18 as in the case of the antenna 4.

Next, FIG. 2 shows an example of a specific circuit of the mixer 3. In the figure, a signal in an intermediate frequency band (1035 to 1335 MHz) of a satellite broadcast received signal is input to a first input terminal 26. The second input terminal 27 receives a television reception signal (76 to 770 MHz) in the FM, VHF or UHF band. The output terminal 28 outputs a television reception signal (broadcast wave) in the FM or VHF or UHF band and a signal in the intermediate frequency band of the satellite broadcast without mutual influence. Reference numeral 45 denotes a bypass filter provided as necessary in the connection circuit 29, for example, 1035 to 1335 MHz.
It has a pass band for passing the signal of z. Reference numeral 46 denotes a current passing circuit which is connected in parallel with the high-pass filter 45 when the high-pass filter 45 is used. Then 47
Is a low-pass filter interposed as necessary in the connection circuit 30. The low-pass filter has an inductor (coil) in a series arm, and its pass band is, for example, 10 to 770 MHz. The low-pass filter 47 uses an inductor (coil) in a series arm in order to allow passage of current (current of electric power for operating the device). Reference numeral 48 denotes a capacitor connected in parallel to the positive characteristic thermistor 31, which is used as needed when the high frequency signal passing characteristic of the thermistor 31 is poor, and is used to pass the high frequency signal well. Note that the high-pass filter 45 and the low-pass filter 47 are connected to the signals in the intermediate frequency band of the satellite broadcast and the FM, VHF, UHF
It is used to eliminate mutual influence with the signal of the band,
If means for performing the same function as the high-pass filter 45 is built in the converter 11 and means for performing the same function as the low-pass filter 47 are built in the amplifier 35, they are unnecessary.

Next, FIG. 3 shows an example of a circuit of the television receiving antenna 5 (VHF antenna). In the figure, 50 indicates an antenna element. 51 is a trap coil, 52 is 30
Matching device to convert 0Ω to 75Ω impedance, 53
Are output terminals, which are housed in the antenna feed box.

When the output terminal 53 of such an antenna is connected to the second input terminal 27 in FIG. 2 using, for example, a coaxial cable, the second input terminal 27 is connected to the matching device 52 in the antenna for operating the device, as is apparent from FIG. Power (DC)
A short circuit occurs. However, as shown in FIG. 2, since the positive characteristic thermistor 31 is interposed in the junction circuit 30 of the mixer, the current flowing through the connection circuit 30 is limited as described above.

Next, FIG. 4 shows an example of the characteristics of the positive-characteristic thermistor 31. When a normal power-consuming device is connected to the second input terminal 27, the power supply of the tuner 14 is When the power is turned on and the electric power for operating the device is sent out, a current of a normal value, for example, about 100 mA flows through the positive characteristic thermistor 31 of the connection circuit 30 through the above-described path as indicated by A. On the other hand, when the second input terminal is in a short-circuit state, a large current flows instantaneously as shown by B after the switch is turned on, and as a result, the positive temperature coefficient thermistor 31 generates heat. Due to the heat generated, the resistance value of the thermistor 31 rapidly increases, and as a result, the current rapidly decreases as shown in FIG. The current value is, for example, about 20 mA.

Next, FIG. 5 shows a different example of the current-free television receiving antenna, in which the UHF and VHF mixer 55 and the third
This shows an example in which a VHF receiving antenna 54 similar to the figure is combined. In the mixer 55, reference numeral 56 denotes a VHF input terminal to which an output terminal 53 of an antenna 54 is connected using a transmission line 61. 57 is a UHF input terminal to which a well-known UHF antenna is connected. An output terminal 58 is connected to the second input terminal 27 of the mixer 3 using the transmission line 42. Reference numeral 59 denotes a known low-pass filter, and reference numeral 60 denotes a known high-pass filter.

Even in such a configuration, when the output terminal 58 is connected to the second input terminal 27 of the mixer 3, the second input terminal
27 is short-circuited to the power for operating the device via the low-pass filter 59 and the matching device 52. However, also in this case, as described above, the PTC thermistor 31 prevents an excessive current from flowing due to a short circuit.

Parts that are functionally considered to be the same as or equivalent to those in the preceding figure are given the same reference numerals as in the preceding figure, and redundant description is omitted.

(Effects of the Invention) As described above, according to the present invention, when it is desired to receive satellite broadcasting, power for operating the device is received by the active unit 11 of the antenna 1 for receiving satellite broadcasting from the terminal device 2 to operate it. In addition to transmitting a received signal to the terminal device 2 to receive a satellite broadcast, it is possible to receive a television broadcast by connecting a television receiving antenna to the second input terminal 27 of the mixer 3. Even if the antenna 4 is used with a device to be used, the second input terminal
27, it is possible to receive the power for operating the device from the terminal device 2 to the power use device 35 in the antenna 4 and operate it, transmit the received signal to the terminal device 2, and receive the television broadcast. .

In addition, even if the second television receiver antenna is of a power-free type and the second input terminal 27 capable of supplying electric power is short-circuited due to the connection of the antenna 5, even if the second input terminal 27 is short-circuited, (2) Since the positive characteristic thermistor 31 is provided in the connection circuit 30 between the input terminal 27 and the output terminal 28, when an excessive current due to a short circuit flows through the circuit 30, the resistance value of the thermistor 31 increases. There is a feature that the current flowing to the two input terminals 27 can be limited to a small value. This prevents the voltage drop due to the short circuit and prevents the power supply to the active portion of the satellite broadcast receiving antenna from being continued without any trouble, has the effect of maintaining the normal reception of the satellite broadcast, and causes an excessive current to flow. There is also an effect that damage to the power supply unit of the terminal device 2 can be prevented.

[Brief description of the drawings]

The drawings show an embodiment of the present application. FIG. 1 is a block circuit diagram of a satellite broadcast receiver, FIG. 2 is a circuit diagram showing an example of a mixer circuit, and FIG. 3 is a VHF television receiving antenna. FIG. 4 is a circuit diagram, FIG. 4 is a graph showing operating characteristics of a positive temperature coefficient thermistor, and FIG. 5 is a circuit diagram showing a different embodiment. 1 ... antenna for receiving satellite broadcasting, 11 ... active part, 2 ...
Terminal device, 3 ... Mixer, 26 ... First input terminal, 27 ...
2nd input terminal, 28 ... output terminal, 31 ... positive characteristic thermistor.

Claims (1)

(57) [Claims] 1. An antenna for receiving a satellite broadcast having an active portion which operates to receive a power for operating a device and outputs a reception signal, and transmits power for operating the device and receives a reception signal. And a first input terminal connected to the active portion of the satellite broadcast receiving antenna, a second input terminal for connecting a television receiving antenna, and an output terminal connected to the terminal device. And a first input terminal and an output terminal, and a second input terminal and an output terminal of the mixer, wherein electric power for operating the device is passed from the output terminal to the first and second input terminals. , A satellite broadcast receiver connected to the first and second input terminals to output terminals so as to pass a received signal, wherein a power supply is provided in a connection circuit between the second input terminal and the output terminal in the mixer. Machine used The normal characteristic thermistor which keeps the current passing normally, and increases the resistance value of itself when an excessive current flows due to a short circuit to limit the current from the output terminal to the second input terminal to a small value is interposed. A satellite broadcast receiving apparatus.