JPS58125956A - Driving system of antenna switch - Google Patents

Abstract

PURPOSE:To eliminate apparent ill effect exerted on a picture due to switching action of an antenna switch, by switching the antenna switch synchronously with a video synchronizing signal supplied from a tuner circuit. CONSTITUTION:A signal A turned on by a control circuit 10 is fed to a D type FF circuit 14 when an external control switch 13 is operated and then stored in the circuit 14 with a vertical synchronizing signal SP. Then a signal B led out of the circuit 14 is turned on and off and applied to a delaying circuit 15 to be delayed. This delayed ON output signal C is applied to an antenna switch 6. The delay time of the circuit 15 is set so that the switching time point of the switch 6 is identical with a time point which is approximate to the next signal SP. Therefore, even if noise arises at the switching time point, the noise is limited at a masked area of the CRT of a picture receiver, so that no visual problem is produced. The case when the signal A fed from the circuit is changed to OFF from ON is referred to the same.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving an antenna switch of an image receiving, recording and reproducing apparatus such as a video tape recorder.

In recent years, home video, so-called video tape recorders (hereinafter referred to as VTRs), have become widespread. Generally, a VTR is equipped with a 9-way divider and an antenna switcher, and can receive high-frequency signals (television signals) from an antenna or public listening equipment, and can record and play back programs on its own. If you put it on the TV side, it becomes a distributor.
A high-frequency signal is also supplied to the external receiver through the antenna switcher, allowing the external receiver to receive programs on alternate programs. Also, by flipping the antenna switch to the video side, you can copy the program being recorded to an external receiver, and even record recorded images! 4
1! Of course, you can also play it back and watch it on an external receiver. In such a VTR, the input and output impedance of the distributor is matched when the antenna switch is placed on the TV side, but when the antenna switch is placed on the video side, one output end of the distributor is matched. If it becomes open, impedance matching cannot be achieved, which may disturb the phase of the video signal recorded on the recording/reproducing device and cause fluctuations in level. In addition, in conventional VTRs, the antenna switcher switches from the TV side to the video side at an arbitrary time, which sometimes causes unsightly noise in the center of the image, and sometimes affects the synchronization signal, making it difficult to synchronize. There was a drawback that the phenomenon of disturbance occurred. This phenomenon is particularly noticeable when a contact switch such as a relay or slide switch, which has a long period of unstable on/off operation, is used as an antenna switch.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the conventional VTR, and to improve the switching operation of the antenna switcher by
2) To provide a driving method for an antenna switching device that does not cause sharp shadows on images and does not disturb synchronization.

In order to achieve the above object, the antenna switching device driving method of the present invention performs switching operation of the antenna switching device in synchronization with a video synchronization signal included in a high frequency signal from a tuner circuit.

The present invention will be explained in detail below with reference to an embodiment shown in one drawing.

Figure 1 shows a conventional VTR that is the premise for implementing this invention.
FIG. 2 is a circuit block diagram of FIG.

In the figure, high frequency signals from antennas 1 to V are applied to a distributor 4 via an input terminal 3 of a VTR 2. The high frequency signal applied to the distributor 4 is divided into two outputs, one of which is led to the tuner circuit 5, and the other to the external output terminal 7 via the TV side terminal 6a and common terminal 6b of the antenna switch 6. It has become. tuner circuit 5
The high frequency signal input to is converted to a target frequency (for example, a designated counter program channel) and is applied to an amplification/separation circuit 8. The amplification/separation circuit 8 separates the signal into a video signal, an audio signal, and a synchronization signal. These video signals, audio signals, and synchronization signals are applied to the recording/reproducing circuit 9 and recorded. The synchronization signal is also applied to the control circuit 10 and used for controlling the speed of the recording head in the recording/reproducing circuit 9 during recording.

The recording/reproducing circuit 9 is connected to the RF converter 11, and the reproduction signal read out from the recording/reproducing circuit 9 during reproduction is R
The F converter 11 converts the signal into a high-frequency signal of an appropriate frequency, outputs the signal, and outputs it to the external output terminal 7 via the video side terminal 6c of the antenna switch 6 and the common terminal 6b. External output terminal 7 is connected to external receiver 12 .

Further, the antenna switch 6 is constituted by a relay, and is configured to be driven to switch from the terminal 6a to the terminal 6C or vice versa when an operation signal from the external operation switch 13 is applied via the control circuit 10.

In the circuit shown in FIG. 1, when, for example, the external receiver 12 receives a main program and the recording/reproducing circuit 9 records a subprogram, the antenna switch 6 is turned to the TV side, that is, the terminal 6a, and the tuner circuit 5 The alternate program to be recorded is selected. The high frequency signal of the scheduled program received by the antenna 1 is applied to the external receiver 12 via the input terminal 6 - distributor 4 -> antenna switch 6 -> external output terminal 7 and is received. On the other hand, a high-frequency signal of a counterprogram received by the antenna 1 is recorded in the recording/reproducing circuit 9 via the input terminal 6 - the distributor 4 - the tuner circuit 5 - the amplification/separation circuit 8 . Under this condition, that is, if you want to display the video signal being recorded as an image on the external receiver 12 while watching the other program, operate the external operation switch 13 to switch the antenna switch 6,
Flip it to the video side, that is, to the terminal 6c side. Antenna switcher 6
When the is turned to the 6C side, the video signal of the program being recorded in the recording/playback circuit 9 is transferred from the RF converter 11 to the antenna switch 6.
→It is added to the external receiver 12 via the path of the external output terminal tare and is projected as an image. Also, when reproducing the video signal recorded in the recording/reproducing circuit 9 and displaying it on the external receiver 12, the video signal is applied to the external receiver 12 through the same route as when displaying the entire video signal during recording.

In the above circuit, the external operation switch 13 is operated at an arbitrary timing, and the antenna switch 6 is driven according to that timing, so depending on the timing,
Synchronization may be disrupted due to V noise occurring in the center of the video signal to be recorded, the synchronization signal being skipped, or unnecessary parnu occurring.

In order to solve the above problems, the embodiment of the present invention provides some additional circuits to the circuit shown in FIG. FIG. 2 shows the main parts of a circuit according to an embodiment of the present invention.

In FIG. 2, the same numerals as those shown in FIG. 1 indicate the same circuit parts, and other parts not shown have the same connection configuration as shown in FIG. 1. The feature of this embodiment is that the vertical synchronizing signal SPi from the amplification/separation circuit 8 is added to the control circuit 10, and the D-type flip-flop circuit 14
This is something I try to add to the list as well. When the control circuit 10 applies a signal A from the external operation switch 13 to the D-type flip-flop circuit 14, the D-type flip-flop circuit 14 stores this signal A and derives an output signal B based on the vertical synchronization signal SP. Furthermore, the output B of the D-type flip-flop circuit 14 is applied to an on/off delay circuit 15, and the on/off delay circuit 15 derives an output signal C, and this signal C is used to output an antenna switch 6'ff: It is designed to perform a driving or switching operation.

Next, the operation of the circuit shown in FIG. 2 will be explained with reference to the timing waveform diagram of each part of the circuit shown in FIG.

First, when the external operation switch 13 is operated to switch the antenna switch 6, the signal A (at time t1) turned on by the control circuit 10 is inputted to the D-type flip-flop circuit 14, and this signal A is determined by the vertical synchronizing signal SP (at time t2), which is discussed after the rise of signal A υ.
The data is stored in the flip-flop circuit 14. And output signal B' (i7 derived.

This signal is applied to the input of the on/off delay circuit 15. Then, the on/off delay circuit 15 outputs the on output signal C (at time t3) after the delay time of TD. This signal C is applied to the antenna switch 6 as a signal for driving the relay of the antenna switch 6. Antenna switching unit 5 and 6 are operated after the time TD required for relay operation (at time 44)
The switching operation from terminal 6a to terminal 60 is performed at . The sixth diagram shows a state in which the antenna switch 6 is switched from the terminal 6a to the terminal 6C at time t4. Here, the delay time TD is 4 at the 9th time point considering the relay operation time TO, that is, the switching operation time point of the antenna switching device 6 is the 9th vertical synchronization signal s.
The time point is selected to be close to p (time t5). If the switching operation point is close to the vertical synchronization signal SP, even if noise occurs, it will occur at the lower end of the brown color of the receiver, that is, at the masked area.

There is no visual problem. Furthermore, since the switch is made at a position slightly different from the synchronizing signal, it does not affect the synchronizing signal.

Also, when the signal A from the control circuit 10 turns from on to off, the off signal 7) is read by the next vertical synchronization signal SP (time t7) at time q, and the signal B is turned off from that point on. Then, after a delay time TD from this point, the output C of the delay circuit 15 becomes low at time C (t8).

Subsequently, after the operating time TO of the relay has elapsed, the switching operation of the antenna switch B is performed, and the terminal 6C side is switched to the terminal 6a side (at time t9). This time t9 is also close to the time t10 at which the next vertical synchronization signal SP is applied.

In the above embodiment, since a relay is used as the antenna switching device 6, the operating time TO
However, if a diode switch or the like having a relatively quick operation time is used as the antenna switch, this may be ignored and the delay time TD may be lengthened by that time.

Further, when a diode switch or the like is used as the antenna switch, the antenna switch may be operated in synchronization with a horizontal synchronization signal instead of a vertical synchronization signal.

Further, in the above embodiment, a delay time TD is provided to perform the switching operation near before the synchronization signal is generated.
If the switching operation is performed in the vicinity after the synchronization signal is generated, there is no need to provide any particular delay time TD.

Furthermore, in the above embodiment, as a VTR, a distributor,
Although the description has been made assuming that the tuner circuit and the recording/reproducing circuit are configured in one case, the tuner circuit and the recording/reproducing circuit may be configured in separate cases.

Furthermore, although the above embodiment has been described in connection with Example H, the present invention is not limited thereto; it goes without saying that it can also be applied to an image receiving, recording and reproducing apparatus similar to a VTR, such as a video disk apparatus.

As described above, according to the driving method of the antenna switching device of the present invention, the switching operation of the antenna switching device is performed in synchronization with the video synchronization signal included in the high frequency signal from the tuner circuit. By appropriately selecting the timing shift of the operation, even if noise occurs in the image, it will appear at the edge of the screen where the mask is applied, making it possible to obtain an image with virtually no shadows. Furthermore, since the synchronization is not disrupted when switching antennas, the screen will not be distorted due to synchronization disruption during playback.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram of a VTR which is a premise for implementing this invention, and Fig. 2 is a VTR showing an embodiment of this invention.
FIG. 3 is a timing waveform diagram of each part of the circuit for explaining the operation of the embodiment circuit shown in FIG. 2. 1: 7 antenna, 2: VTR, 5: input m. 4: Distributor, 5: Tuner circuit, 6: Antenna switch, 7: Output terminal, 8: Amplification/separation circuit, 9: Recording/reproducing circuit, 10: Control circuit, 11: RF converter, 12: External receiver, 13: External operation switch, 14: D-type flip-flop 1 circuit, 15:
On/off delay circuit. Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Shigeru Nakamura

Claims (1)

[Claims] (1) An input terminal that receives high-frequency signals from the outside. A divider that distributes the high frequency signal, a device that receives one of the divided high frequency signals through a tuner circuit, records and reproduces a video signal included in this high frequency signal, and a terminal that outputs the high frequency signal to an external receiver. a high-frequency converter that outputs the video signal from the recording/reproducing device by including it in a high-order e-converter; and a high-frequency converter that switches the other high-frequency signal distributed by the distributor and the high-frequency signal from the high-frequency converter to the output terminal. In an image receiving, recording and reproducing device comprising an antenna switching device connected to a. A driving method for an antenna switching device, characterized in that a switching operation of the antenna switching device is performed in synchronization with a video synchronization signal included in a high frequency signal from the tuner circuit.