JPS58143677A - Monitor device - Google Patents

Abstract

PURPOSE:To switch automatically the receiving channel of a monitor device by the output of a channel discriminating circuit provided on an RF unput signal path. CONSTITUTION:The RF output of a CATV converter, a VTR, a VDR, or the like is supplied to an amplifying circuit 2 through an input terminal 1. A channel discriminating circuit 3 is connected to the amplifying cirucit 2, and the amplification output is discriminated to give a switching control signal to a channel switching circuit 4. A receiving part 6 of a monitor device 5 is set to the state, where a prescribed channel is received, by this switching control signal. Thus, a receiver 7 can perform monitoring on the channel corresponding to the input signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a monitor device coupled to video equipment. For more details, please refer to CATV converter, VT
Connect a video device such as an R (video tape recorder) or a VDB (video disk recorder) that has at least two channels as an RP output channel to a monitor device, and set the receiving channel of this monitor device to the output channel of the video device. It is also equipped with an automatic switching function.

Conventionally, in this type of monitor device, the reception channel has to be manually selected in accordance with the output channel of the video equipment, which has the drawback that the operation is complicated and mistakes are easily made.

The present invention has been made with the aim of solving these conventional drawbacks, and it uses a channel discrimination circuit to discriminate an input video signal, and a channel selection signal from a channel switching circuit based on the discriminated output signal. output,
This channel selection signal is used to select a target channel in the receiving section of the monitor device, and automatically sends the target video signal from the video equipment to the receiver side of the monitor device.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the block diagram of FIG. 1, (1) is an RF signal input terminal from a video device, (2) is an amplifier circuit, (3) is a channel discrimination circuit, and (4) is a channel switching circuit. (5) is a monitor device, which includes a receiver (6) and a receiver (7).
It is made up of.

The specific circuits of the channel discrimination circuit (3) and channel switching circuit (4) are shown in FIG. In this Figure 2, the channel discrimination circuit (3) is an IC (8) for AFC (automatic frequency control circuit) of a general TV receiver, since the CATV converter outputs in America, Canada, etc. are channels 2 and 3. is used, and other coils (9) αυaz1 capacitors (1:l (14)
The channel switching circuit (4) is composed of a transistor an@1) and a resistor (23Q324nH). 1B and -B are power supply terminals, respectively.

Next, the present invention will be explained in detail.

If the RF multiplied signal is not input because no video equipment is connected to the input terminal (1), the voltages shown in Figures 4 and 5 are applied to the 7th and 8th bins of the IC (8), respectively. (■,) is output. At this time, the pace voltage of the transistor (to) of the channel switching circuit (4) is obtained by dividing the potential difference between the voltage (■.) and the power supply voltage (-B) with a resistor @ (c), and the voltage that cuts off the transistor gate. is maintained. The same applies to the other transistor 01).

Therefore, no channel selection signal is sent to the receiving section (6) of the monitor device (5).

Next, it is assumed that a video device is connected to the input terminal (1) and a low channel signal (fLv%fLs) is applied, for example. Here, fLV is the video carrier frequency of the lower of the two channels, fL&
is also the audio carrier frequency. Also, fHV is the video carrier frequency % of the higher channel among the three channels, fHV is the audio carrier frequency, and fc is fL
& indicates the intermediate frequency of fHV. These fL
V, fL&'Q, fHV, and fH8 are shown in FIG. 3 as frequency characteristics when the input BP flaw signal is passed through a bandpass filter (not shown).

By adding the above fLV%fL8, AF
For C) The hinge bin of C (8) has f as shown in Figure 4.
A voltage (Vl) is generated between LV and fL&. This voltage (Vυ) increases the base voltage of the transistor, making it conductive. Therefore, the emitter of transistor (2) has the voltage (VB
) is generated, which becomes a channel selection signal and is applied to the receiving section (6). Then, the receiving section (6) of this monitor device (5) automatically switches to the receiving state of the lower channel, and the image is displayed on the image receiving section 11 (7).

Similarly, when a high channel signal (fHv%fas) is applied, the receiving section (6) of the monitor device (5)
Then, the reception state is automatically switched to the higher channel, and the image is displayed on the receiver (7).

In the above embodiment, the case of two channels is shown, but the present invention is not limited to this.

As described above, in the present invention, the RP input signal from the video equipment is discriminated by the channel discrimination circuit, the channel switching circuit outputs the channel selection signal, and the monitor device switches to the receiving state of the corresponding channel. , the desired channel is automatically switched to the desired channel without having to do so manually as in the prior art, thus eliminating the complexity and mistakes of operation. In addition, since it is only a simple configuration added to a conventional device, there is almost no cost increase.Furthermore, if the AFC IC of a television receiver is used as a channel discrimination circuit, it is small and operates accurately. .

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a monitor device according to the present invention, Fig. 2 is a specific electric circuit diagram of the main parts of the same, Fig. 3 is a frequency characteristic diagram of a bandpass filter, and Fig. 4 is an AFCJ9J
Output characteristics diagram of IC bin 7 and channel switching circuit,
FIG. S is an output characteristic diagram of the third bin of the AFC IC and the channel switching circuit. (ri...RF signal input terminal, (2)...amplifier circuit,
(3)...Channel discrimination circuit, (4)...Channel switching circuit, (5)...Monitor device, (6)...Receiving unit, (7)...Receiver, (
8)...AFCpAIC0 Patent Applicant General Co., Ltd. Figure 1 Figure 2 0 / Figure 3

Claims (3)

[Claims] (1) A video device having at least two channel outputs is coupled to a monitor device, and the video output signal from the video device is switched to the receiving channel in accordance with the output channel of the video device. a channel discrimination circuit that discriminates the frequency according to the frequency and outputs it as a signal of a predetermined voltage; a channel switching circuit that outputs a channel selection signal corresponding to each channel based on the output of the channel discrimination circuit; 1. A monitor device comprising: a receiver for selecting a target channel based on the channel selection signal and transmitting a target video signal to a receiver. (2) The channel discrimination circuit is the AvC of the television receiver.
A monitor device according to claim 1, which uses an IC. (3) The monitor device according to claim 1, wherein the channel switching circuit includes transistors that are respectively opened and closed by output signals corresponding to reception channels of the channel discrimination circuit.