JPS5850668Y2 - Television equipment for communal viewing and viewing - Google Patents

Description

[Detailed description of the invention] This invention relates to a television device for communal viewing and viewing in which power supply voltage is applied to the amplifier only while broadcasting is being performed in a communal viewing television facility. .

FIG. 1 is a schematic block diagram of a general communal viewing television facility, in which a signal received by an antenna 2 is amplified by a head amplifier 4, and further by an intermediate line amplifier 6L62.
... is amplified and supplied to the output terminal 8 to which a television receiver is connected.

10 is a power supply device, and the power supply voltage supplies an operating voltage to the head amplifier 4, intermediate line amplifiers 61, 62, . . . through a signal path.

However, in the past, operating voltage was supplied to each amplifier regardless of the presence or absence of broadcasting, which resulted in high power consumption and short lifespan of each amplifier.

This invention solves the above-mentioned deficiencies of the prior art by supplying operating voltage to the intermediate line amplifier only when radio waves are received and operating voltage is applied to the head amplifier.

This invention will be described in detail below with reference to the embodiments shown in FIGS. 2 to 4.

Referring to FIG. 2, the output signal of head amplifier 4 is supplied to intermediate line amplifier 6 via coupling capacitors 12 and 14, and the signal amplified by intermediate line amplifier 6 appears at output terminal 8 via coupling capacitor 16.

A television receiver (not shown) is connected to the output terminal 8 via a coupling capacitor 17.

Further, an AC power supply 18 for supplying operating voltage to the amplifiers 4 and 6 is connected to the output terminal 8.

A power supply switching circuit 20 is provided in association with the head amplifier 4.

The power supply switching circuit 20 includes a broadcast detection sub-amplifier 22 for detecting the presence or absence of broadcast radio waves, a relay 24 driven by the sub-amplifier 22, a transformer 26 connected to the 81 contact side of the relay 24, and a bridge. A full-wave rectifying and smoothing circuit consisting of a full-wave rectifying circuit 28 and a constant voltage circuit 30, and a half-wave rectifying and smoothing circuit consisting of a resistor 32, a diode 34, and a capacitor 36 connected to the A2 contact side are provided. .

The diode 38 is a block diode for separating the half-wave rectifying and smoothing circuit from the head amplifier 4.

A switching contact a3 of the relay 24 is coupled to a signal line 44 through a low-pass filter consisting of a choke coil 40 and a capacitor 42.

Also associated with the intermediate line amplifier 6 is a power supply switching circuit 46.
is provided.

The power supply switching circuit 46 includes a DC component detection circuit 50 connected to the secondary winding 48b of the transformer 48 via a capacitor 49.
, a relay 52 driven by the DC component detection circuit, a transformer 54 connected to the b1 contact side of the relay 52, a full-wave rectifying and smoothing circuit including a bridge-type full-wave rectifying circuit 56, and a constant voltage circuit 58. and a resistor 6 connected to the b2 contact side.
0, a diode 62, and a half-wave rectifying and smoothing circuit consisting of a capacitor 64.

A diode 66 connects the half-wave rectifying and smoothing circuit to the intermediate amplifier 6.
Blocks for separation.

It is a diode.

The primary winding 48a of the transformer 48 is coupled to the output terminal 72 of the signal line 44 via a low pass filter consisting of a choke coil 68 and a capacitor 70.

The switching contact b3 of the relay 52 is connected to a signal line 78 for transmitting the output signal of the amplifier 6 via a low-pass filter also composed of a choke coil 74 and a capacitor 76.

In the above device, when there is no broadcast signal, relay 2
The switching contact a3 of the relay 52 and the switching contact b3 of the relay 52 are both connected to the contact a2. It is assumed that it is connected to the b2 side.

At this time, the AC supplied from the operating AC power supply 18 is
Signal line 78, choke coil 74, primary winding M48a1 choke coil 68 of transformer 48, choke coil 40
, a contact a2 and a resistor 32 to a half-wave rectifying and smoothing circuit including a diode 34 and a capacitor 36.

As a result, only the sub-amplifier 22 becomes operational, and no operating voltage is supplied to the head amplifier 4.

On the other hand, in this state, only a half wave of the operating AC voltage flows through the primary winding 48a of the transformer 48 of the power supply switching circuit 46, so the DC component detection circuit 50 is connected to the capacitor 49 from the secondary winding 48b. A half-wave voltage is supplied through the

As a result, the DC component detection circuit 50 detects the DC component,
The relay 52 is driven to the state where the contact b2 is closed as described above.

Now, when the sub-amplifier 22 in operation receives a radio wave of a certain strength or higher, it drives the relay 24 and closes the switching contact a.
3 to the contact al side as shown by the solid line.

As a result, the full-wave rectifier circuit 28 and the constant voltage circuit 30 operate, and an operating voltage is supplied to the head amplifier 4, so that the head amplifier 4 becomes in an operating state.

Width amplifier 22 is also kept in operation by the operating voltage provided through diode 38.

When the power supply switching circuit 20 operates in a full-wave rectification state, a full-wave current flows through the transformer 48 of the power supply switching circuit 46, so its positive and negative magnitudes are equal, and the DC component detection circuit 50 does not detect the DC component. .

As a result, the switching contact b3 of the relay 52 is switched to the contact bl side as shown by the solid line, the full-wave rectifier circuit 56 and the constant voltage circuit 58 are operated, and the intermediate line amplifier 6 is put into an operating state.

The DC component detection circuit 50 continues to operate due to the operating voltage supplied through the diode 66.

As mentioned above, when there is a broadcast, the head amplifier 4 button and the intermediate line amplifier 6 are activated, and the amplified broadcast signal is sent from the output terminal 8 to each television.

When there is no broadcasting, the output of the sub-amplifier 22 is at a low level as described above, and the contact of the relay 24 is a2 as shown by the dotted line.
It returns to the closed state and the head amplifier 4 stops operating.

Further, the DC component detection circuit 50 detects the DC component, and the relay 5
Similarly, the contact point 2 is returned to the closed state of b2 as shown by the dotted line.
The operation of the intermediate line amplifier 6 is stopped.

In this way, according to the device of this invention, the residual voltage is supplied to the amplifier that consumes power only when there is a broadcast, so there is no wasted power consumption, and energy costs can be saved.

In addition, even when two or more stages of intermediate line amplifiers are provided in the signal line, the presence or absence of broadcasting can be determined by providing a power supply switching circuit equipped with the same circuit as the above-mentioned DC component detection circuit 50 in relation to each amplifier. Needless to say, it is possible to automatically switch between supplying and cutting off power according to the situation.

If necessary, one power supply switching circuit 46 can be shared by all intermediate line amplifiers.

FIG. 3 shows the configuration of the sub-amplifier 22 in more detail. The signal sent from the antenna 2 is amplified by the amplifier circuit 23, detected by the detection circuit 25, and compared with the comparison voltage Vc by the comparison circuit 27. , the relay 27 is activated when the detected voltage is greater than Vc.

The comparison voltage Vc is created by appropriately dividing the voltage of the capacitor 36 shown in FIG. 2, for example, and is set in consideration of the noise level of the detection circuit.

FIG. 4 is a circuit example of the DC component detection circuit 50, in which the voltage supplied from the secondary winding 48b of the transformer 48 via the capacitor 49 is connected in series with diodes 51a, 51b, capacitors 53a, 53b1, resistor 55a. , 55b compares the positive and negative magnitudes, and the voltage representing the comparison result is supplied to the relay 52 via a low-pass filter 59 and a transistor amplifier circuit 61.

When no increased voltage is applied to the head amplifier 4, a half-wave current flows through the transformer 48, so the positive/negative voltage comparator circuit 57 generates, for example, a positive voltage, and this voltage is applied to the filter 5.
9 to the amplifier 61, which puts the relay 52 in the first state (in the embodiment, contact b2 is closed), and when the operating voltage is applied to the head amplifier 4, a full-wave current is supplied to the transformer 48. flows, the output voltage of the positive and negative voltage comparison circuit 57 is O, and the relay 52 is set to the second state (contact b1 is closed).
Drive.

As described above, according to the communal viewing and viewing television apparatus of this invention, the intermediate line amplifier, which consumes a large amount of power, is supplied with operating voltage only when there is a broadcast. The additional power supply switching circuit 46 may be a simple circuit with extremely low power consumption, and the overall power consumption can be kept low.

Furthermore, since the power supply switching circuit connected to each intermediate line amplifier uses the superimposed operating current as a power supply switching signal, one broadcast wave detection circuit (sub-amplifier 22) is required regardless of the number of intermediate line amplifiers. be.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram of a conventional communal viewing television facility, Fig. 2 is a schematic block diagram of an embodiment of a communal viewing television system according to this invention, and Fig. 3 is a block diagram of a conventional communal viewing television facility. A block diagram showing the sub-amplifier 22 in further detail.
FIG. 4 is a circuit diagram showing an example of the DC component detection circuit 50 also shown in FIG. 4... Head amplifier, 6... Intermediate line amplifier, 1
8... Operating power supply, 20... Head amplifier power supply switching circuit, 24... Relay, 28... Full wave rectifier circuit,
34... Half-wave rectifier circuit, 44.78... Signal source, 4
6... Intermediate line amplifier power supply switching circuit, 48...
Transformer, 50... DC component detection circuit, 52... Relay 56... Full wave rectifier circuit.

Claims (1)

[Claims for Utility Model Registration] A head amplifier that amplifies a signal received by an antenna;
1 at least one intermediate line amplifier that amplifies the output of the head amplifier; an operating AC power supply that supplies an operating voltage to each amplifier via a signal path through which the amplified signal is transmitted; The DC voltage generated by full-wave rectification of the AC voltage supplied from the power supply is supplied to the head amplifier to operate it only when there is broadcasting, and when there is no broadcasting, the AC voltage is and a broadcast wave detection type head amplifier power supply switching circuit that continues to operate with a DC voltage generated by half-wave rectification of the head amplifier and stops supplying the DC voltage to the head amplifier. An intermediate line amplifier power switching circuit is provided in connection with the intermediate line amplifier, and the intermediate line amplifier power switching circuit is configured to perform half-wave rectification by the head amplifier power switching circuit. a detection circuit that detects whether full-wave rectification is being performed by the presence or absence of a positive/negative unbalanced state of the operating voltage sent through the signal path; a rectifier circuit that rectifies the AC voltage supplied from the power source and supplies the obtained DC voltage to the intermediate line amplifier as an operating voltage to bring it into an operating state. It is characterized by the presence of The above communal viewing and viewing television equipment.