JP2997810B2 - amplifier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an amplifier used to amplify a television signal received by an antenna and send it to a television receiver.

(Prior Art) An amplifier of this type is arranged near an antenna and has two types of amplifier circuits, and a power supply unit is arranged near a receiver and supplies power to the amplifier. The television signal from the amplification unit is received by the television receiver via the power supply unit (for example, Japanese Utility Model Publication No. 61-4329).
No. 8).

The amplifier is configured to operate by applying an alternating current from a power supply unit to two types of amplification circuits and two types of variable attenuation circuits provided in the amplification unit.

(Problems to be Solved by the Invention) The conventional amplifier has a configuration in which one of the two types of amplifier circuits operates at a positive voltage and the other operates at a negative voltage. In this case, when the amplifier section of the amplifier is mounted, the first amplifier circuit, which is one of the amplifier circuits, and the second amplifier circuit, which is the other amplifier circuit, have different configurations. Is complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to make it possible to apply voltages of the same polarity to all the amplifier circuits of an amplifier so as to be convenient for design and mounting. It is to provide an amplifier.

(Means for Solving the Problems) In order to solve the above problems, the invention of the present application has taken measures as described in the claims, and the operation is as follows.

(Operation) The power supply unit is installed near the television receiver, and the amplification unit is installed near the outdoor antenna.

In the power supply unit, the voltage of the positive half-wave of AC is adjusted by the first voltage adjustment circuit in order to adjust the output level of the amplification unit of the first television signal. Further, in order to adjust the output level of the amplifying section of the second television signal, the voltage of the negative half-wave of AC is adjusted by the second voltage adjusting circuit. The alternating current in which the positive half-wave and the negative half-wave are respectively adjusted in voltage is applied to the amplifier from the power supply unit through the power supply line. In the amplifier, the AC from the power supply unit is converted into a DC voltage of either positive or negative polarity by a power supply circuit, and the first
And the second amplifier circuit. The positive half wave of the alternating current is applied to a first variable attenuation circuit through a polarity discrimination circuit, and the negative half wave is applied to a second variable attenuation circuit through a polarity discrimination circuit. The first television signal is attenuated by a first variable attenuator with an attenuation amount corresponding to the voltage value of the positive half wave,
The signal is amplified by the first amplifier circuit to reach the mixing circuit. On the other hand, the second television signal is attenuated by the second variable attenuator with an attenuation corresponding to the voltage value of the negative half-wave, amplified by the second amplifier, and reaches the mixing circuit. The first and second television signals are mixed in a mixing circuit, sent out to a power supply line, reach a power supply unit, and sent from there to a television receiver for reception.

(Embodiment) Drawings showing an embodiment of the present application will be described below.

FIG. 1 shows a system diagram of a television receiving system using an amplifier. 1 is VH as the first TV signal
A first antenna 2 for receiving an F television signal and a second antenna 2 for receiving a UHF television signal as a second television signal, respectively. Reference numeral 3 denotes an amplification unit of the amplifier, the configuration of which will be described later. 3a indicates a first input terminal, 3b indicates a second input terminal, and 3c indicates an output terminal. The first input terminal 3a is connected to the first antenna 1 by the feeder line 4 and to the second antenna
Are connected to the second antenna 2 by the feeder line 5, respectively. As the feed lines 4 and 5, for example, coaxial cables are used. Reference numeral 6 denotes a power supply unit, the configuration of which will be described later. 6A indicates an input terminal, and 6B indicates an output terminal. Reference numeral 7a denotes a first operation knob for adjusting the level of a VHF television signal. Reference numeral 7b denotes a second operation knob for adjusting the level of a UHF television signal. Reference numeral 8 denotes a power supply line for connecting the amplifying unit 3 and the power supply unit 6, and for example, a coaxial cable is used. Reference numeral 9 denotes a series unit interposed on the feeder line 8, and 9A
Indicates an input terminal, 9B indicates an output terminal, and 9C indicates a television terminal. Incidentally, as this series unit 9, between the input terminal 9A and the output terminal 9B, in addition to the television signal, the power supply AC also passes.
A so-called current passing type is used. Reference numerals 10 and 11 denote television receivers, respectively. Reference numerals 12 and 13 denote feed lines, for example, coaxial cables are used. 14 is a building, and a power supply unit 6 as shown in the figure.
Is installed near the television receiver 11 in this building 14, and the amplification unit 3 is installed outside the building 14, for example, on a roof.

Next, FIG. 2 is a circuit diagram showing the amplification unit 3 in a partial block. Reference numeral 15 denotes a first band pass filter, which passes a VHF television signal. 16 is a second bandpass filter,
Pass UHF television signals. Reference numeral 17 denotes a first preamplifier for amplifying a VHF television signal, and is provided as necessary. Reference numeral 18 denotes a second preamplifier for amplifying a UHF television signal, and is provided as necessary. Reference numeral 19 denotes a first amplifier circuit, which amplifies a VHF television signal in a wide band. Reference numeral 20 denotes a second amplifier circuit for amplifying a UHF television signal in a wide band. The first preamplifier 17 and the first amplifying circuit 19, and the second preamplifier 18 and the second amplifying circuit 20, are circuits operating at voltages of the same polarity, for example, positive voltages. It has a configuration. In this example, the first preamplifier is used.
17 and the first amplifier circuit 19 use the VHF band television signal, and the second preamplifier 18 and the second amplifier circuit 20 use the UHF band signal, respectively.
An amplifier having F low band and VHF high band, or a single channel and all channels may be used. Reference numeral 21 denotes a first variable attenuation circuit for attenuating a VHF television signal in a wide band. L1a and L2a are coils that block high frequency television signals but allow low frequency AC and DC to pass, D1a is a PIN diode, and ZD1a is a zener diode. R1a is a resistor provided to allow a predetermined bias current to flow through the Zener diode ZD1a to obtain a predetermined Zener voltage, and R2a is a resistor provided to limit the current flowing through the diode D1a and protect the diode D1a. Shown respectively. COa indicates a smoothing capacitor. Next, reference numeral 22 denotes a second variable attenuation circuit for attenuating a UHF television signal in a wide band. The second variable attenuation circuit 22 is configured to operate with a negative power supply while the first variable attenuation circuit 21 operates with a positive power supply. Therefore, the parts considered to be the same in terms of function are denoted by reference numerals a instead of b,
A duplicate description will be omitted. Reference numeral 23 denotes a rectifying diode for providing a positive polarity voltage to the first variable attenuation circuit 21 as a polarity determination circuit, and reference numeral 24 denotes a rectification diode for providing a negative polarity voltage to the second variable attenuation circuit 22 as a polarity determination circuit. Shown respectively. Reference numeral 25 denotes a power supply circuit which extracts a positive voltage for operating the amplifiers 17 and 18 and the amplifier circuits 19 and 20 from an output terminal 25B from an alternating current applied to the input terminal 25A, and a detailed circuit configuration thereof will be described later. Reference numeral 26 denotes a constant voltage circuit using a three-terminal regulator or the like. Reference numeral 27 denotes a mixing circuit, which is configured by combining a low-pass filter for passing a VHF television signal and a high-pass filter for passing a UHF television signal. Reference numeral 28 denotes a power supply separation filter. In the above configuration, the signals handled by the first band-pass filter 15, the second band-pass filter 16, the first variable attenuation circuit 21, the second variable attenuation circuit 22, and the mixing circuit 27 Can be variously changed according to the band of the signal amplified by the first amplifier circuit 19 and the second amplifier 20 described above.

Next, FIG. 3 is a circuit diagram partially showing the power supply unit 6 in a block diagram. For 30, a commercial AC 100V is applied to the power plug.
Reference numeral 31 denotes a power transformer for reducing the voltage of a 100 V AC to 20 to 30 V. Reference numeral 32 denotes a first voltage adjusting circuit for adjusting a positive half wave of alternating current. On the other hand, reference numeral 33 denotes a second voltage adjusting circuit for adjusting a negative half wave of AC. VR1a and VR1b indicate variable resistors, respectively, and the variable resistor V
R1a is the same as the above-mentioned first operation knob 7a and also the variable resistor VR1.
b is connected to the second operation knob 7b described above. D3a and D3b indicate rectifying diodes, respectively. Reference numeral 34 denotes a power supply separation filter.

In the above-mentioned configuration, the power supply unit 6 has a first operation knob 7a for adjusting the level of the VHF television signal.
But also to adjust the level of the UHF television signal
Are operated, respectively. As a result, the variable resistors VR1a and VR1b each indicate a resistance value corresponding to the operation.
The commercial AC applied to the power plug 30 is stepped down by the power transformer 31. Then, the positive half-wave becomes an alternating current indicating a voltage value corresponding to the resistance value of the variable resistor VR1a, and the negative half-wave becomes an alternating current indicating a voltage value corresponding to the resistance value of the variable resistor VR1b. It joins the feed line 8.

The alternating current described above is applied to the output terminal 3c of the amplifying unit 3, is separated by the power supply separation filter 28, and is applied to the power supply circuit 25. Here, after being set to the positive voltage, the voltage is set to a constant positive voltage by the constant voltage circuit 26, and the first and second preamplifiers 17, 18
And supplied to the first and second amplifier circuits 19 and 20, respectively. The positive half wave of the alternating current separated by the power supply separation filter 28 passes through the diode 23 and is applied to the first variable attenuation circuit 21. In the first variable attenuation circuit 21, a current flows through the Zener diode ZD1a via the resistor VR1a to generate a constant voltage. A current having a magnitude corresponding to the voltage value of the positive half-wave also flows through the circuit including the resistor R1a, the coil L1a, the PIN diode D1a, the coil L2a, and the Zener diode ZD1a. The PIN diode exhibits a high-frequency resistance value according to the magnitude of the current.
Therefore, the first variable attenuating circuit 21 has an amount of attenuation corresponding thereto.

On the other hand, on the side of the diode 24 and the second variable attenuator 22, the same operation as that of the diode 23 and the first variable attenuator 21 is performed, except that the polarity is different.

When the power supply unit 6 and the amplification unit 3 operate in this manner, the first
The VHF television signal received by the antenna 1 is applied to the first input terminal 3a. And the first bandpass filter 1
5, passes through the first preamplifier 17, is attenuated by the first attenuating circuit 21 with an attenuation amount corresponding to the voltage value of the positive half-wave, and then is attenuated by the first amplifying circuit 19. It is amplified and enters the mixing circuit 27. The UHF television signal received by the second antenna 2 is applied to a second input terminal 3b. Then, the signal passes through the second band-pass filter 16 and the second preamplifier 18 and is attenuated by the second attenuating circuit 22 with an amount of attenuation corresponding to the voltage value of the negative half-wave. The signal is amplified by the amplifier circuit 20 and is added to the mixing circuit 27. The VHF and UHF television signals mixed by the mixing circuit 27 pass through the power supply separation filter 28 and are sent to the power supply line 8 from the output terminal 3c. These television signals pass through the input terminal 6A of the power supply unit 6, pass through the power supply separation filter 34, and the output terminal 6B, and are sent to the television receiver 11.

Here, when the resistance value of the variable resistor VR1a is changed to increase the voltage value of the positive half wave appearing at the input terminal 6A, the voltage value applied to the diode 23 in the amplifier 3 also increases. Then, the bias current flowing through the PIN diode D1a also increases, the high-frequency resistance decreases, and the attenuation of the first variable attenuation circuit 21 decreases. Conversely, when the voltage value of the positive half wave is reduced, the attenuation of the first variable attenuation circuit 21 increases. Therefore, if the first operation knob 7a is operated to change the resistance value of the variable resistor VR1a, the output level of the VHF television signal in the amplifier 3 can be changed.

Similarly, by operating the second operation knob 7b to change the resistance value of the variable resistor VR1b, the voltage value of the negative half-wave appearing at the input terminal 6A is changed, and the attenuation of the second variable attenuation circuit 22 is reduced. Can be increased or decreased. Therefore, in the amplification unit 3
The output level of the UHF television signal can be changed.

When adjusting the above-described variable resistors VR1a and VR1b, the amplifiers 17 and 1 are supplied from the power supply circuit 25 regardless of the resistance value.
Needless to say, the variable ranges of the variable resistors VR1a and VR1b are set so that the voltages necessary for the normal operation of the amplifier 8 and the amplifier circuits 19 and 20 are supplied.

As for the circuit configuration of the amplifier 3, the first variable attenuator 21 is provided on the subsequent stage of the first amplifier 19, and the second variable attenuator 22 is provided on the subsequent stage of the second amplifier 20. May be obtained.

Next, the circuit configuration of the power supply circuit 25 will be described. FIG. 4 is a circuit diagram showing an example of the power supply circuit 25. T1 indicates a power transformer, and the winding ratio of the primary winding L3 to the secondary winding L4 is 1: 1.
Or something more than that is used. D4, D5,
D6 and D7 are rectifying diodes, and these four diodes constitute a full-wave rectifier circuit. C1 indicates a smoothing capacitor. In the configuration shown in FIG. 4, when a power supply circuit is used, both a positive half-wave and a negative half-wave can be used as a power supply voltage, so that power supply efficiency is high. Also, since the ripple content can be reduced, it is suitable for amplifying a television signal with less hum modulation.

Next, FIG. 5 is a circuit diagram showing a power supply circuit having a different configuration. Elements having the same or equivalent functions as those in the previous figure are denoted by the same reference numerals with the letter e added thereto, and redundant description will be omitted. C2 and C3 indicate capacitors, and D8 and D9 indicate diodes. In the power supply circuit having this configuration, even if the voltage applied to the input terminal 25Ae is low, the voltage supplied from the output terminal 25Be to each of the amplifier circuits 19 and 20 can be increased. This means that the variable range of the above-described variable resistors VR1a and VR1b can be made wider than in the case of the previous example, and as a result, the output level adjustment range of the amplifier 3 can be expanded.

(Effect of the Invention) As described above, in the present application, the first amplifier circuit and the second amplifier circuit
The polarity of the supply voltage of the amplifier circuit can be unified, and the circuit design becomes easy.

In addition, since the first and second amplifier circuits can use components common to both circuits, it is economical in terms of component management.

[Brief description of the drawings]

The drawings relate to an embodiment of the present application. FIG. 1 is a system diagram of a television receiving system using an amplifier, FIG. 2 is a circuit diagram partially showing an amplification unit, and FIG. FIG. 4 is a circuit diagram showing an example of a power supply circuit, and FIG. 5 is a circuit diagram showing a different configuration of the power supply circuit. 3 amplifying section, 6 power supply section, 7a first operation knob, 7b second operation knob, 8 power supply line, 11
TV receiver, 19 first amplifier circuit, 20 second amplifier circuit, 21 first variable attenuation circuit, 22 second variable attenuation circuit, 23, 24 polarity discriminating circuit , 25 ... Power supply circuit, 2
7 a mixing circuit, 28 a power supply separation filter, 31 a power supply transformer, 32 a first voltage adjustment circuit, 32 a second voltage adjustment circuit, 34 a power supply separation filter.

Claims (1)

(57) [Claims] 1. An amplifier comprising an amplifier for amplifying a first television signal and a second television signal and transmitting the amplified signal to a power supply line, and a power supply for transmitting an alternating current to the amplifier.
The power supply unit includes a first voltage adjustment circuit that adjusts a voltage value of a positive half-wave in the alternating current to be sent to the amplification unit, and a second voltage adjustment circuit that adjusts a voltage value of a negative half-wave in the alternating current. A first variable attenuation circuit and a first amplification circuit processed by the first amplification circuit.
And a mixing circuit that mixes the television signal with the second television signal processed by the second variable attenuating circuit and the second amplifying circuit of the television signal and sends the mixed signal to the power supply line. And a polarity discriminating circuit for supplying the negative half-wave to the second variable attenuating circuit, and the negative half-wave to the second variable attenuating circuit. An amplifier characterized in that AC is converted into a DC voltage of the same polarity by a power supply circuit and supplied to the first and second amplifier circuits.