JP2966259B2 - AC / DC power supply type amplifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplifier operable with either an AC power supply or a DC power supply, and is particularly suitable for use in a CATV booster installed either indoors or outdoors. .

[0002]

2. Description of the Related Art Recently, a cable television system capable of avoiding radio interference such as ghosts and transmitting image signals such as television broadcasts and movies in an area where radio interference is present, in an apartment house or in an urban area. (CA
TV). In order to subscribe to the CATV and receive television broadcasts, movies, and the like, it is necessary to branch a signal from the CATV line that has been set up and lead a transmission line indoors.

In this case, for example, in a strong electric field area, the electric field of a TV signal propagating in space may be stronger than the electric field received from a CATV line. A ghost is caused by a signal to be received originally. Further, since the line is further branched from the line drawn indoors from the CATV line and connected to a plurality of TV receivers or the like, the electric field received from the CATV line becomes insufficient and noise may be generated on the screen. . Therefore, C
2. Description of the Related Art Conventionally, a signal from an ATV line is amplified before being drawn indoors, thereby preventing a front ghost or noise.

[0004] This pattern will be described with reference to FIGS. 4 and 5. FIG. 4 shows a case where the booster 102 is installed outdoors, and FIG. 5 shows a case where the booster 108 is installed indoors. Booster 1 as shown in FIG.
02 is installed outdoors, the outlet is generally not provided outdoors.
2 must be powered. Therefore, it has been considered to supply power to the booster 102 from indoors.

That is, power is supplied as follows. Branch device 1 inserted from CATV line 100
The signal branched by 01 is supplied to the booster 102 via the protector 103. The signal amplified by the booster 102 is led indoors along the lead-in line 104 and input to the power supply unit 105. This power supply unit 105
Is supplied with a commercial power supply of AC 100 V, and converts the step-down AC power supply (for example, AC 30 V) into the above-described lead-in line 10.
4 to the booster 102.

[0006] As described above, the AC power supplied to the booster 102 is converted into DC by the rectifying / smoothing means provided in the booster 102 and supplied to the amplifier in the booster 102. The signal from the CATV line 100 amplified by the amplifier in the booster 102 passes through the drop-in line 104 and the power supply unit 105 as described above, and is input to the home terminal 106 provided indoors. From this home terminal 106
A signal is supplied to the V receiver 107. Note that the protector 103 is provided to prevent a TV receiver or the like installed indoors from receiving the influence of lightning or the like guided to the CATV line 100. This protector 103 is generally constituted by an arrester.

Next, FIG. 5 shows a case where the booster 108 is installed indoors. In this case, as a matter of course, power is supplied to the booster 108 using a commercial power outlet provided indoors. That is, the signal from the CATV line 100 is branched by the branching device 101 and drawn indoors via the security device 103. Then, the signal is amplified by a booster 108 installed indoors and input to the home terminal 106. The booster 108 is supplied with AC 100 V from an outlet provided indoors.

[0008] Therefore, the power supply circuit provided in the booster 108 reduces, rectifies and smoothes the supplied AC 100 V and supplies it to the amplifier provided in the booster 108. The home terminal 106
Is supplied to the TV receiver 107 and transmitted on the CATV line 100, and is displayed on the screen of the TV receiver 107.

[0009]

As shown in FIGS. 4 and 5, power supply methods are different between a case where the booster is installed outdoors and a case where the booster is installed indoors. Must be prepared as a product with different specifications,
There has been a problem that an increase in the number of parts causes an increase in cost. Accordingly, an object of the present invention is to provide an AC / DC power supply type amplifier that can be used with either an AC power supply or a DC power supply.

[0010]

In order to achieve the above object, the present invention provides an AC power supply for stepping down and rectifying and smoothing AC100V which is a commercial power supply, and a DC power supply transmitted from a room via a signal line. A DC power supply unit that can be switched is provided in the booster so that the DC power supply is automatically detected when the DC power supply is supplied, and the DC power supply is supplied.

[0011]

According to the present invention, since it is possible to use either an AC power supply or a DC power supply, there is no need to increase the number of products, and the cost can be reduced by the effect of mass production. In addition, since the supply of DC power is automatically detected and switched, erroneous use due to a difference in power can be prevented.

[0012]

FIG. 1 shows a configuration of a booster according to a first embodiment which is an AC / DC power supply-use amplifier according to the present invention. The booster 20 shown in FIG, 8 is an input terminal to which a signal from the CATV line is input, a signal input from the input terminal 8 is inputted to the amplifier 1 via the coupling capacitor C _1, an amplifier 1 Amplified and coupled capacitor C ₂
And output from the output terminal 9 via the. Power is supplied to the amplifier 1 from a power supply line.

First, a description will be given of a case where the booster 20 is installed indoors. When the booster 20 is installed indoors, the commercial power supply AC100V is applied to the transformer 3, and a low AC voltage that is transformed by the transformer 3 and reduced to the secondary side is output. This AC voltage is full-wave rectified by the full-wave rectifier _{4 and} smoothed by the capacitor C4.
Further, the voltage between both ends of the capacitor C ₄ is stabilized by the regulator 5 and supplied to the amplifier 1 via the power supply line. Capacitor C ₃ connected to the output side of the regulator 5 is a capacitor for stabilizing the DC voltage. At this time, the contact 22 of the relay 2 is open, and the smoothed voltage is not output from the output terminal 9.

Next, a case where the booster 20 is installed outdoors will be described. When the booster 20 is installed outdoors, the AC 100 V commercial AC power supplied to the power supply unit 10 from an outlet provided indoors is supplied to the power supply unit 10.
The voltage is reduced, rectified and smoothed, converted into a DC voltage, and supplied to the output terminal 9 of the booster 20 via the line 11. The DC voltage supplied to the output terminal 9 is applied to the relay coil 21 of the relay 2 via the choke coil 6. Then, the relay coil 21
Is energized by this DC voltage, and the relay 2
Contact 22 is closed. Therefore, the DC voltage applied to the output terminal 9 is supplied to the regulator 5 via the contact 22 and is stabilized before being supplied to the amplifier 1. In this case, the DC voltage connected to the input side of the regulator 5 is cut off by the full-wave rectifier 4 and is not applied to the transformer 3.

The line 11 is a line 11 through which an amplified signal output from the output terminal 9 is transmitted. The signal is supplied to a TV or the like through the power supply unit 10. Further, a signal may be supplied to the TV via the home terminal. The choke coil 6 prevents the signal amplified by the amplifier 1 from being transmitted to the power supply, utilizing the fact that the impedance of the inductance is high at high frequencies. Further, the capacitor C ₂
Is to prevent the DC voltage supplied to the output terminal 9 from being applied to the amplifier 1 by utilizing the fact that DC does not pass. The lightning arrester 7 is made up of an arrester or the like, and drops lightning transmitted on the line 11 to ground as the name implies.

In the AC / DC power supply type amplifier shown in FIG. 1, when the booster 20 is operated by supplying DC power from the power supply unit 10 provided indoors, the commercial power supply AC 100 V is erroneously supplied to the booster. When supplied, the AC voltage induced on the secondary side of the transformer 3 is full-wave rectified by the rectifier _{4 and} smoothed by the capacitor C ₄ . The smoothed voltage is applied to the relay coil 21 via the contact 22 of the relay 2 and is output from the output terminal 9 via the choke coil 6.

For this reason, even if the power supply unit 10 is cut off, the operation of the relay 2 is continued, so that the state where the DC voltage is output to the output terminal 9 is maintained. In this case, when the output terminal 9 is short-circuited for some reason, the output terminal 9 is short-circuited.
, The current is not supplied to the relay coil 21 and the relay 2 returns but an excessive short-circuit current flows through the transformer 3 and the rectifier 4 until the relay 2 returns. Therefore, an embodiment of an AC / DC power supply amplifier which does not cause this defect will be described below.

FIG. 2 shows an AC / DC power supply type amplifier according to a second embodiment of the present invention. The AC / DC power supply type amplifier shown in FIG. 2 is further provided with a second relay contact 23 on the relay 2 in addition to the one shown in FIG. 1, and this second relay contact 23 is connected to one output of the transformer 3. , And the rectifier 4. However, the second relay contact 23 is a contact that is closed when the relay 2 is not operating. As described above, when the second relay contact 23 is connected, the relay 2 operates when DC power is applied to the output terminal 9 to close the contact 22 provided on the relay 2 as described above, Is opened. Therefore, the DC power supply is
, The input side of the rectifier 4 is cut off by the second relay contact 23 connected between the rectifier 4 and the transformer 3.

Therefore, even if the AC power is supplied by mistake while the DC power is being applied to the output terminal 9, this AC power is not applied to the rectifier 4, and the output of the rectifier 4 Output to the output terminal 9 is prevented. When only the AC power is applied, the second relay contact 23 is closed. Therefore, the AC power is supplied to the rectifier 4, smoothed, and then stabilized by the regulator 5. The second embodiment of the present invention shown in FIG. 2 is similar in configuration and operation to the first embodiment of the present invention shown in FIG.
The description of the other parts is omitted.

Next, a third embodiment of the AC / DC power supply type amplifier of the present invention is shown in FIG. The third embodiment is different from the second embodiment in that only one contact is required for the contact of the relay, and a low-cost general-purpose relay can be used. is there. This figure 3
The AC / DC power supply type amplifier shown in FIG. 1 has a relay contact 24 of one circuit instead of the relay contact 22 and the relay contact 23 of the relay 2 shown in FIG. The movable contact a and the fixed contact c of the relay contact 24
Is provided between the output of the rectifier 4 and the regulator 5, and the fixed contact b and the movable contact a are provided between the choke coil 6 and the regulator 5. However, the movable contact a and the fixed contact c of the relay contact 24 are normally closed contacts that are closed when the relay 2 is not operating, and the fixed contact b and the movable contact a are not operated by the relay 2 It is a normally open contact that is sometimes open.

As described above, when the relay contact 24 is connected, the relay 2 operates when a current is supplied to the relay coil 21 when DC power is applied to the output terminal 9 as described above. The movable contact a and the fixed contact b are closed, and the movable contact a and the fixed contact c are opened. Therefore, the DC power supplied to the output terminal 9 is applied to the input of the regulator 5, and the rectifier 4 is connected to the movable contact a and the fixed contact c of the relay contact 24 connected between the rectifier 4 and the regulator 5. Is shut off.

Therefore, even if the AC power is erroneously supplied to the transformer 3 when the DC power is applied to the output terminal 9, the voltage obtained by rectifying the AC power by the rectifier 4 is not applied to the regulator 5. The output of the rectifier 4 can be prevented from being output to the relay coil 21 and the output terminal 9. When only the AC power is applied, since the movable contact a and the fixed contact c of the relay contact 24 are closed, the AC power is supplied to the rectifier 4, smoothed, and then supplied to the regulator 5. Be stabilized. The third embodiment of the present invention shown in FIG. 3 is similar in configuration and operation to the first embodiment of the present invention shown in FIG. 1 except for the points described above. And

As described above, according to the present invention, since the DC power is supplied to the amplifier 1 using the relay 2, there is almost no voltage drop as compared with the case where an electronic switch is used. Can be. Further, the relay 2 has high reliability, is strong in surge, and has no polarity, so that the handling becomes easy. Further, since the relay 2 does not require a circuit for driving the relay 2 in particular, it is not necessary to provide a drive circuit unlike an electronic switch. However, depending on the application, an electronic switch can be used instead of the relay 2.

In the above description, the present invention has been described as relating to a CATV amplifier. However, the present invention is not limited to this, and can be applied to a general amplifier installed outdoors or indoors. is there. Further, it is preferable to use a coaxial cable for a line for supplying a signal to the booster 20 and a line for outputting a signal shown in FIG.

[0025]

Since the AC / DC power supply type amplifier of the present invention is constructed as described above, it is possible to use either an AC power supply or a DC power supply, and it is necessary to prepare two types of products for AC and DC. Disappears. Therefore, the cost can be reduced due to the mass production effect. Further, since the supply of the DC power is automatically detected and switched to the DC power, it is possible to prevent a different power from being supplied to the amplifier by mistake. Further, if a relay is used for switching the DC power supply, the voltage drop of the switch can be made almost zero, and the power supply can be used effectively.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment of an AC / DC power supply type amplifier according to the present invention.

FIG. 2 is a circuit diagram of a second embodiment of an AC / DC power supply type amplifier according to the present invention.

FIG. 3 is a circuit diagram of a third embodiment of an AC / DC power supply type amplifier according to the present invention.

FIG. 4 is a diagram illustrating a power supply method when a conventional booster is installed outdoors.

FIG. 5 is a diagram illustrating a power supply method when a conventional booster is installed indoors.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 amplifier 2 relay 3 transformer 4 rectifier 5 regulator 6 choke coil 7 lightning arrester 8 input terminal 9 output terminal 10, 105 power supply unit 11 line 21 relay coil 22, 23, 24 contact 100 CATV line 101 branch 102, 108 booster 103 protector 104 Drop-in line 106 Home terminal 107 TV receiver C ₁ , C ₂ coupling capacitor C ₃ Stabilization capacitor C ₄ Smoothing capacitor

Claims (5)

(57) [Claims] An input terminal and an output terminal are respectively connected to a signal line, and an amplifier inserted in series with the signal line; a power supply circuit for rectifying and smoothing an AC power supply and converting the AC power supply to a DC power supply; And a relay operated by a DC power supplied from one of the inserted signal lines. When the AC power is supplied, the AC power is rectified and
Smoothing and supplying power to the amplifier from the power supply circuit,
When the DC power is supplied, by operating the relay, the DC power is supplied to the amplifier through the power circuit through the contact point of the relay, and the AC / DC power supply is used. Type amplifier. 2. The AC / DC power supply type amplifier according to claim 1, wherein a relay coil of said relay is connected to said signal line via a choke coil. 3. The constant voltage circuit according to claim 1, wherein the power supply circuit comprises a rectifying / smoothing circuit and a constant voltage circuit, and a contact on an output side of the relay is connected to an input side of the constant voltage circuit. Or the AC / DC power supply type amplifier described in 2. 4. A relay having a second contact, the second contact being connected to the input side of the rectifying / smoothing circuit, and the input side of the rectifying / smoothing circuit being cut off when the DC power is supplied. 4. The method according to claim 1, wherein
The AC / DC power supply type amplifier according to any one of the above. 5. The relay is provided with a contact of one circuit consisting of a normally closed contact and a normally open contact, power is supplied from the AC power supply through the normally closed contact, and power is supplied from the DC power supply through the normally open contact. The AC / DC power supply type amplifier according to any one of claims 1 to 3, wherein power is supplied to the amplifier.