JPH0546386Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a modulator with a switch, and more particularly to a modulator with a switch having a switch capable of switching between a normal television signal and a scrambled television signal.

2. Description of the Related Art Generally, a video tape recorder (VTR) includes a modulator that converts the video and audio signals of the video tape recorder into the television broadcast signal band of an empty channel so that they can be connected to the antenna terminal of a normal television receiver and played back. (RF modulator) is provided. Further, the modulator is usually provided with a high frequency switch so that the signal from the antenna and the signal from the modulator can be appropriately switched and output to the television receiver.

In addition, in recent years, paid broadcasting such as cable television (CATV) has been introduced, but in such broadcasting, subscribers who have subscribed to a signal that can be viewed directly on a regular TV receiver can view the program. A scrambled television signal is usually broadcast so that non-subscribers cannot view it. The scrambled television signal is unscrambled by a descrambler such as a CATV receiving unit owned by the subscriber and returned to a clean television signal before being scrambled, so that a normal image can be seen on the television receiver. It becomes possible to view and record on a video tape recorder.

Here, when considering a system using CATV, VTR, and television receiver, a conventional modulator with a switch can be considered as a system as shown in FIG. 3. The system shown in Figure 3A starts from terminal 33.
CATV broadcasting companies supply scrambled normal television signals and scrambled television signals. If you want to record these broadcasts on a VTR or watch them on a TV receiver, the scrambled and unscrambled normal television signals can be supplied as is to the VTR 32, but the scrambled television signals need to be fed to the CATV receiver. 30, a normal image cannot be obtained unless descrambled, and the CATV receiving unit 3
0 to the VTR 32, the signal is distributed by the distributor 29, and the A/B switch 31 switches which television signal to select.

In addition, in the case of the system shown in Figure 3B, terminal 38
CATV is supplied with scrambled television signals from a CATV broadcasting supplier.
The receiving unit 34 unscrambles the A/B
The signal is supplied to one terminal (for example, the B terminal) of the switch 36. On the other hand, a normal television broadcast signal is input from the antenna 35, and the A/B switch 36
is supplied to the other terminal (for example, the A terminal). Therefore, by switching the A/B switch 36, normal television and CATV broadcasts can be converted to VTR.
You can record it on your 37 or watch it on your TV.

Problems to be Solved by the Invention However, when recording CATV broadcasts or outputting to a television receiver with a conventional VTR equipped with a modulator with a switch, A/B switches 31, 3
6, it is necessary to switch between a scrambled television signal and a scrambled television signal, and since the A/B switches 31 and 36 are usually provided independently, operability is poor; Further, when the configuration is as shown in FIG. 3A, a distributor 29 is required, which causes problems such as large insertion loss.

The present invention has been developed in view of the above points, and includes a switch that allows switching between scrambled television signals and unscrambled television signals without the need for separate distributors or A/B switches. The purpose is to provide a modulator.

Means for Solving the Problems The present invention provides a switch equipped with a high frequency switch that switches between an input broadcast signal and a signal from a modulator that modulates a video signal and an audio signal into a high frequency signal that can be input to the antenna terminal of a television receiver. The modulator includes: a first switching means for switching between supplying the input broadcast signal to the high frequency switch and outputting it to an externally provided decoder; and a first switching means for switching the input broadcast signal to the high frequency switch. A second switching means is turned off when the first switching means outputs the input broadcast signal to the outside, and is turned on to supply the broadcast signal decoded from the decoder to the high frequency switch. means, the first switching means and the second switching means are housed integrally with the modulator and the high frequency switch in a shield case, and a broadcast signal input to which the input broadcast signal is input. a broadcast signal output terminal for supplying the input broadcast signal to the decoder, a decode signal input terminal for inputting the decoded signal from the decoder, and a terminal for transmitting the output signal of the high frequency switch to the antenna terminal of the television receiver. The configuration is such that connection with external equipment is made via the TV output terminal supplied to the TV.

Function: The first switching means switches between supplying the first input broadcast signal to the high frequency switch and outputting it to the outside. The second switching means operates in conjunction with the first switching means such that the first switching means supplies the first input broadcast signal to the high frequency switch OFF, and the first switching means supplies the first input broadcast signal to the high frequency switch. Turns on when outputting a signal to the outside. Therefore, when the first input broadcast signal is being supplied to the high frequency switch, the second switching means is turned off, the second input broadcast signal is no longer supplied to the high frequency switch, and the first input broadcast signal is not supplied to the outside. When the signal is output, the second switching means is turned on and the second input broadcast signal is supplied to the high frequency switch.

The high frequency switch and the first and second switching means are integrally housed in a shield case as a modulator, and are connected to an external device via an input broadcast input terminal, an input broadcast output terminal, a decoded signal input terminal, and a TV output terminal. Since the switches are integrated with the modulator in the shield case, it is easy to install VCRs, etc.

Embodiment FIG. 1 shows a block diagram of an embodiment of the present invention. In the figure, 1 is a video tape recorder and 2 is a video tape recorder.
CATV receiving unit, 3 indicates the shield case.

A modulator (MOD) 13 is enclosed in a shield case 3 and built in the video tape recorder 1. The modulator 13 supplies the reproduction signal of the video tape recorder 1 to the antenna terminal of the television receiver, and converts it into an RF signal in the television broadcast band of an empty channel so that it can be reproduced.
The CATV receiving unit 2 is a device that converts a scrambled television signal into a television signal that can be viewed on a normal television receiver in order to prevent unauthorized viewing.

Inside the shield case 3 are switches 10, 11,
12 and a modulator 13 are included. The switch 12 is a switch for switching between supplying a television broadcast signal to the antenna terminal of the television receiver or supplying a video playback signal frequency-converted to a television signal of an empty channel by a modulator 13. The switch 10, which is the first switching means, and the switch 11, which is the second switching means, are interlocked, and when the switch 10 is connected to the terminal 14, the switch 11 is turned off, and the switch 10 is connected to the terminal 15. When the switch 11 is turned on, the switch 11 is turned on.

When the switch 10 is connected to the terminal 14 side, the television signal input to the terminal 4 is supplied from the terminal 8 to the video tuner in the video tape recorder 1, and at this time the switch 12 is connected to the terminal 16 side.
If it is connected to the side, it will also be supplied to the television receiver. Also, when the switch 10 is connected to the terminal 15 side, the television signal input from the terminal 4 (at this time, it is a CATV broadcast signal) is transmitted to the terminal 6.
The signal is output from the CATV receiving unit 2, where the CATV broadcast signal is descrambled and supplied to the terminal 7.

The CATV broadcast signal supplied to terminal 7 is supplied to the video tuner from terminal 8 via switch 11, and at this time, switch 12 switches to terminal 16.
If it is connected to the side, it is also supplied to the television receiver from terminal 9.

As described above, according to this embodiment, it is possible to selectively supply a CATV broadcast signal and a normal television broadcast signal to a television receiver or a video tuner without using a distributor. In addition, in this embodiment, switch 1
Although 0 and 11 are configured with high frequency switches, they can also be configured with electronic switches.

FIG. 2 shows a circuit diagram in the case of an electronic switch. In the figure, 18 and 19 indicate electronic switches. Next, its operation will be explained. A voltage is constantly applied to the terminal 20, and the electronic switch 18
A divided voltage by resistors R ₁ and R ₂ is applied to the electronic switch 19, and a divided voltage by resistors R ₃ and R ₄ is applied to the electronic switch 19.

The electronic switches 18 and 19 are controlled to be turned on or off depending on whether a voltage is applied to the terminal 22 or not. When no voltage is applied to the terminal 22, the divided voltage of the resistors R ₁ and R ₂ causes the diodes D ₁ to _{D 3 to}
A forward voltage is applied to it, turning it on, and
Since a reverse voltage is applied to the diodes D ₄ to D ₆ by the resistor R ₅ , the diodes D 4 to D 6 are turned off. Therefore, the television signal input to the terminal 21 is connected to the capacitor C ₃ , the diodes D ₁ to D ₃ , and the capacitor C ₁
is output to the video tuner in the video tape recorder via the terminal 23, and is also output to the video tuner in the video tape recorder via the switch 24.
When the signal is connected to the terminal 25 side, the signal is also supplied to the television receiver from the terminal 26.

On the other hand, when a predetermined voltage is applied to the terminal 22, a forward voltage is applied to the diodes _D4 to _D6 , which turn them on, and the diodes D1 _{to D6} are turned on.
A voltage in the opposite direction is applied to D ₃ to turn them off. Therefore, the television signal input to the terminal 21 is sent from the terminal 27 to the CATV receiving unit (not shown) via the circuits consisting of the diodes _D4 to _D6 , the capacitor C, and the coil _L3 .
Here, the CATV broadcast signal is descrambled, converted into a signal that can be viewed on a normal television receiver, and then supplied to the terminal 28.

When voltage is applied to terminal 22, the resistance
When the divided voltage of R ₃ and R ₄ is less than the voltage applied to terminal 22,
Since a forward voltage is applied to the diodes D ₇ -D ₉ , they are in the on state, and the signal supplied to the terminal 28 is connected to the capacitor C ₆ , the diodes D ₇ -D ₉ ,
The signal is output from the terminal 23 to the video tuner via the capacitor _C8 , and when the switch 24 is connected to the terminal 25 side, the signal is supplied from the terminal 26 to the television receiver.

Note that the capacitors C ₁ , C ₃ , C ₅ , C ₆ ,
C ₈ and coils L ₃ and L ₄ are for cutting DC components caused by bias voltage and the like. Further, the coils L ₁ and L ₂ connected to the terminal 22 are choke coils that block high frequency signals, and prevent the high frequency signal from the terminal 21 from flowing into the electronic switch 19 and the high frequency signal from the terminal 28 from flowing into the electronic switch 18 side. That's what I do. Furthermore, capacitor C ₂ ,
_C7 is inserted to provide circuit isolation.

Further, according to this embodiment, since the scrambled television signal and the scrambled television signal can be switched only by a switch without using a distributor, insertion loss can be kept low. Furthermore, by using an electronic switch or the like, it is possible to record programs over both scrambled broadcasts and scrambled broadcasts.

Additionally, the switches 10, 11, and 12 are integrally housed in the shield case 3 together with the modulator 13, and connections with external devices are made via terminals 5 to 9. Since the switches 10, 11, 12 and the modulator 13 have been assembled, assembly into the VTR 1 or the like can be easily performed.

Effects of the invention As described above, according to the invention, by switching the first switching means and the second switching means in conjunction with each other, it is possible to switch the input broadcast signal between the high frequency switch and the outside, and to switch the input broadcast signal to the high frequency switch. Since it is possible to switch between the input broadcast signal and the decoded signal, there is no need for a distributor to distribute the broadcast signal between the high frequency switch and the outside, and this also reduces signal loss. has.

In addition, since the switches and the modulator are housed together in the shield case, it has the advantage of being easy to assemble into equipment such as a VTR.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the circuit of the present invention.
FIG. 2 shows a circuit diagram of another embodiment, and FIG. 3 shows a block diagram of a system using a conventional modulator with a switch. 1...Video tape recorder, 2...CATV
Receiving unit, 3... Shield case, 10, 1
1, 12...Switch, 13...Modulator.

Claims (1)

[Claims for Utility Model Registration] A modulator with a switch that has a high-frequency switch that switches between an input broadcast signal and a signal from a modulator that modulates a video signal and an audio signal into a high-frequency signal that can be input to an antenna terminal of a television receiver, a first switching means for switching between supplying the input broadcast signal to the high frequency switch or outputting it to an externally provided decoder; and when the first switching means supplies the input broadcast signal to the high frequency switch; and a second switching means that is turned off when the first switching means outputs the input broadcast signal to the outside, thereby supplying the broadcast signal decoded from the decoder to the high frequency switch. The first switching means and the second switching means are housed integrally with the modulator and the high frequency switch in a shield case, and a broadcast signal input terminal to which the input broadcast signal is input; a broadcast signal output terminal for supplying an input broadcast signal to the decoder; a decode signal input terminal for receiving the decoded signal from the decoder; and a television for supplying the output signal of the high frequency switch to the antenna terminal of the television receiver. A modulator with a switch configured to connect to external equipment via the output terminal.