JPH0453103Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a converter device for receiving CATV signals used in combination with a television receiver.

(b) Conventional technology When receiving a CATV signal transmitted via a cable, a converter device capable of receiving the CATV band is generally provided, and the frequency of the received CATV signal is converted into a signal of an appropriate empty channel by this converter device. It is designed to be supplied to the RF input terminal of a television receiver.

FIG. 2 shows one such converter device specifically for receiving scrambled CATV signals. In the figure, 1 is a converter device, which includes a tuner section 2 into which a CATV signal is introduced into an input terminal 2, and a control section 3 that controls channel selection and descrambling operations of this tuner section. , and an operation section 4 for operating this control section. Reference numeral 5 denotes a television receiver in which CATV frequency-converted by this converter device is input to an RF (high frequency) input terminal 6. Only two large blocks of the supply section 8 are shown.

The tuner unit 2 introduces the CATV signals of each channel (scrambled) that have passed through the splitter 9 and the bandpass filter 10 into a double-conversion type frequency conversion circuit 11, where they are converted into three-channel signals. The frequency is converted and sent to a descrambler circuit 13 through a 3-channel filter 12, and the descrambled 3-channel signal is supplied to the television receiver 5 through another 3-channel filter 14.

On the other hand, the control unit 3 receives and demodulates the FSK signal frequency-multiplexed with the CATV signal described above using the FSK receiver 15, extracts channel data for each channel, addressable data for each subscriber, etc. Each data and a control signal from a function key 16 including a tuning key etc. provided on the operation section 4 is obtained by the CPU 17, and this CPU receives a control signal from the PLL circuit 18 for controlling the local oscillation frequency of the frequency conversion circuit 11 and The operation of the descramble pulse generating circuit 19 is controlled.
At this time, channel data and address ensemble data, which serve as a reference for this control, are stored in advance in the electrically rewritable EAROM 20. In addition,
21 is a demodulation circuit for extracting a reference pulse for creating a descramble pulse which is AM-modulated on the audio carrier wave of the CATV signal.

Further, when the CPU 17 receives an ON control signal from the operation ON/OFF key 22 provided in the operation section 4, it operates the switch control circuit 23 to close the switches 25 and 26 and reverse the operation. When the off control signal is received, the switch 25,
26 are all opened. In each of the above-mentioned circuits in the converter device 1,
Regardless of whether the key 22 is on or off, power is always supplied from the power supply section 27 for the following reason.

That is, in order to be able to receive emergency broadcasts at any time in the event of an emergency, as described above, power is constantly supplied to the converter device 1 to put it in a standby state, and instead of that, by using the above-mentioned operation ON/OFF key 22,
When switched to the off side, the 3-channel CATV signal output from converter device 1 is switched to switch 2.
5, and the other switch 26 cuts off the AC power supplied to the receiver 5 via a power outlet 28 provided in the converter device 1. Therefore, when an emergency broadcast signal is received by the converter device 1 during the standby state, the CPU 17 detects it, turns on both the switches 25 and 26, and the receiver 5 receives the emergency broadcast. It is.

Note that turning on and off the power of the television receiver in this way on the converter device side is described in, for example, Japanese Patent Laid-Open No. 196679/1983.

(c) Problems to be solved by the invention By the way, in the above-mentioned conventional device, there is no problem if the power for the television receiver 5 is obtained from the outlet 28 as described above, but when the power is obtained from the outlet 28 of the television receiver 5, is directly plugged into a building outlet, switching to the off side with the on/off key 22 will not turn off the power to the receiver 5, but the CATV signal from the converter device 1 will not be turned off by the switch 25. Since the signal is blocked, the receiver 5 receives an empty channel (3 channels), which causes noise on the screen, which is inconvenient. In addition, two switches 25 and 26 such as relays are required, and one of the switches 25 must be used for high frequencies, resulting in an increase in cost.

Therefore, the present invention was devised in consideration of these points, and it is possible to put the television receiver into the same state as when it is off by operating the keys on the converter device side, and it has a very simple configuration. The aim is to achieve this.

(d) Means for solving the problem In this invention, the converter device is turned on and off.
When the converter is turned off using the off key, a control section within the device detects this and controls a tuner section within the converter so that an unmodulated carrier transmission channel is received.

(e) Effect According to the above configuration, when the key is turned off, an unmodulated carrier signal is input to the television receiver, so that the demodulated output of this signal, that is, corresponds to the pedestal level of the video signal. A direct current voltage is applied to the picture tube, and the picture tube is cut off and nothing is displayed.

(F) Example Figure 1 shows an example of the present invention, and Figure 2 shows an example of the present invention.
The parts with the same figure numbers as the conventional example shown in the drawings have the same configuration, but the following parts are different. That is, in the converter device 1 of this embodiment, the switches 25 and 26 shown in FIG.
The output line of CPU 1 is directly connected to the output terminal 31, and the power outlet 28 is directly connected to the AC input line 32.
7 detects this, and the tuner unit 2 selects an unmodulated carrier signal transmission channel (a channel that is currently transmitting an unmodulated carrier signal).

To explain the above channel selection operation in detail,
In addition to the addressable data for each subscriber mentioned above, the EAROM 20 also stores frequency division ratios for each channel to be applied to the variable frequency divider circuit in the PLL circuit 18. When the control signal is detected, the EAROM20
Frequency division ratio data and the like regarding the non-modulated carrier signal transmission channel are read out from , and preset in the variable frequency division circuit. As a result, the unmodulated carrier signals of the channels are converted and derived from the frequency conversion circuit 11 into signals of three channels, and these signals are sent to the television receiver 5.

The signal processing unit 7 in the television receiver 5 operates normally even for the unmodulated carrier signal inputted in this manner, and the unmodulated carrier signal is demodulated. The demodulated output at this time becomes a constant DC voltage corresponding to the pedestal level of the video signal, but this DC voltage, that is, the pedestal level is cut off at the cutoff of the picture tube 33 by the DC clamp circuit in the signal processing section 7. Since the light is clamped to the level, nothing appears on the picture tube 33 in this case. Also, at this time, since the audio demodulation output from the signal processing section 7 also becomes a constant voltage, the speaker 34
There is no generation of noise etc. Therefore, the receiver 5
appears to be in an off state.

In a CATV system, at least one or two channels of non-broadcasting are selected in order to avoid noise appearing on the screen or coming from the speakers when a channel that is not broadcasting is accidentally received. Some channels send unmodulated carrier signals, so
The CPU 17 reads the frequency division ratio data of one of the non-modulated carrier signal transmission channels from the EAROM 20 during the above-mentioned off operation.
It is pre-programmed in the program ROM in 17.

(g) Effects of the invention According to the converter device of the present invention, when the converter device is turned off, the supply of CATV signals and power to the television receiver is cut off on the converter device side, thereby reducing the operation of the television receiver. Even if the television receiver is powered directly from the outlet, the receiver can be put on standby for emergency broadcasts in almost the same state as when it is off, and the relay is not configured to stop the receiver. Since there is no need for separate switching means such as the above and their control circuits, the present invention can be realized at low cost without increasing costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment in which the converter device of the present invention is used in combination with a television receiver, and FIG. 2 is a block diagram similarly showing the case in which a conventional converter device is used. 1...Converter device, 2...Tuner section, 3
...Control unit, 4...Operation unit, 5...Television receiver, 22...Operation ON/OFF key.

Claims (1)

[Scope of utility model registration request] The tuner includes a tuner section that receives a CATV signal on which a non-modulated carrier transmission channel is transmitted, a control section that controls the channel selection operation of the tuner section, and an operation section that operates the control section. In the converter device which frequency-converts the CATV signal received by the unit and supplies it to the television receiver, the operation unit is provided with a key for turning on and off the operation independent of the power source of the converter device, The controller is configured to operate the control unit so that the tuner unit receives the unmodulated carrier transmission channel only when the tuner is turned off, and outputs the unmodulated carrier transmission channel to the television receiver. A converter device for CATV reception.