JPH04147404A - Magnetic recorder and reproducer - Google Patents

Abstract

PURPOSE:To judge a recording characteristic fitted for a magnetic tape in a period when a reproduced picture is not affected and to select the recording characteristic during a regular recording by inserting a reference signal into the specific vertical blanking period of an input video signal. CONSTITUTION:The input video signal (a) is supplied to one terminal 2a of an input switching circuit 2 and the reference signal RS from a reference signal generation circuit 4 is supplied to the other terminal 2b. In this case, the input switching circuit 2 changes over a switch to the terminal 2b side in synchronizing with a switch signal for recording (b) supplied to a control input terminal and supplies reference signal RS to a recording characteristic variable circuit 7 only in the harizontal scanning period of the specific vertical blanking period. Thus, the recording characteristic fitted for the magnetic tape is selected by using the reference signal inserted into the vertical blanking period when the reproduced picture of the video signal is not affected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic recording/reproducing device that can record video signals with recording characteristics suitable for the magnetic tape used.

(Prior Art) Magnetic tapes generally have different magnetic properties depending on their material, composition, and manufacturing method. Therefore, if recording is performed with constant recording characteristics regardless of the type of magnetic tape, the characteristics of the magnetic tape may not be fully exploited.

Therefore, some cassette tape recorders are equipped with a tape selector function so that recording can be performed in accordance with the magnetic characteristics of the tape. This tape selector function is designed to maximize the capabilities of the magnetic tape by measuring the recording characteristics of the magnetic tape in advance and recording with the recording characteristics that match the tape.

The block diagram of FIG. 5 shows the configuration of a conventional tape selector function used in a cassette tape recorder.

In this figure, a reference signal output from a reference signal generation circuit 20 is supplied to a recording characteristic variable circuit 21, and the reference signal whose recording characteristic has been changed by this recording characteristic variable circuit 21 is transferred onto a magnetic tape by a recording head 22. recorded. The reference signal recorded on the magnetic tape is immediately reproduced by the reproducing head 23, and the reproduced output signal is supplied to the characteristic determining circuit 24, where the recording characteristic is determined.

In the recording characteristic variable port #I21, the recording characteristic of the reference signal is sequentially changed as many times as the characteristic can be changed, so that the characteristic determining circuit 24 repeats the recording characteristic determination for the number of times to determine the optimum recording characteristic. It can be done.

Once the optimum recording characteristics are determined, signals are recorded on the magnetic tape using these recording characteristics.

(Problems to be Solved by the Invention) By the way, if a video tape recorder has a recording head and a reproducing head independently, it is possible to determine the recording characteristics of a magnetic tape using a method similar to the tape selector method described above.

However, with the conventional tape selector method, the reference signal remains on the magnetic tape after the recording characteristics have been determined, so it is necessary to erase the reference signal by rewinding the tape to the recording start position. What we do is a matter of time.

The present invention has been proposed to solve the above problems, and an object of the present invention is to provide a magnetic recording and reproducing apparatus equipped with a tape selector system that can judge the recording characteristics of a magnetic tape while recording a normal signal. Be self-aware.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, a magnetic recording and reproducing apparatus according to the present invention includes a reference signal generation circuit that generates a reference signal, and an input video signal that receives the reference signal output from the reference signal generation circuit. A switch circuit inserted into a specific vertical blanking period of a signal, a recording characteristic variable circuit that changes the recording characteristic of a reference signal portion of a video signal output from this switch circuit, and a video signal output from this recording characteristic variable circuit. A recording head that records video signals onto a magnetic tape, a playback head that immediately plays back the video signal recorded on the magnetic tape, and the recording characteristics of the reference signal in the playback video signal output from the playback head are the magnetic characteristics of the magnetic tape. The characteristics of the recording characteristics variable circuit are sequentially varied, and when the optimum recording characteristics are selected based on the judgment output signal of the characteristics judgment circuit, and a control circuit that controls the recording characteristic variable circuit so that the input video signal is recorded on the magnetic tape with a recording characteristic.

(Function) According to the above-described configuration, a reference signal is inserted into the vertical blanking period of an input video signal, the recording characteristics of this reference signal are changed to record a video signal on a magnetic tape, and this video signal is immediately played back. The recording characteristics of the reference signal are judged using the reference signal, and the recording characteristics suitable for the magnetic tape are selected using the reference signal inserted during the vertical blanking period that does not affect the reproduced image of the video signal. I can do it.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The block diagram of FIG. 1 shows an embodiment of a magnetic recording/reproducing apparatus according to the present invention.

In this figure, an input video signal a that enters an input terminal 1 is supplied to one terminal 2 a of an input switching circuit 2 and also to a switching signal generation circuit 3 . The other terminal 2b of this input switching circuit 2 is supplied with a reference signal R3 from a reference signal generating circuit 4.

In the switching signal generation circuit 3, a vertical synchronizing signal vS is detected from the input video signal a shown in FIG. b)) and the reproduction switching signal e (see Fig. 2 (
e) Reference> is created. The recording switching signal outputted from the switching signal generating circuit 3 is supplied to the control input terminal of the input switching circuit B2, and is also supplied to the detection control circuit 5. Further, the reproduction switching signal e is supplied to the detection control circuit 5 and the characteristic determination circuit 6. Here, the input switching circuit 2 and the switching signal generation circuit 3 constitute a switch circuit.

In the input switching circuit 2, the switch is switched to the terminal 2b side in synchronization with the recording switching signal S supplied to the control input terminal, and the reference signal R3 is switched to the recording characteristic variable circuit 7 only during the horizontal scanning period of a specific vertical blanking period. be supplied to Note that if the recording switching signal is not input,
Normally, it is switched to the terminal 2a side, and the input video signal a is supplied to the recording characteristic variable circuit 7. With this operation,
Reference signal R3 is inserted into the horizontal scanning period of a specific vertical blanking period of input video signal a.

On the other hand, the detection control circuit 5 generates a characteristic selection signal SC in synchronization with the input recording switching signal S, and supplies it to the recording characteristic variable circuit 7. This allows recording characteristics to be varied 87 times.
Then, the recording characteristics of only the reference signal R3 portion are changed in synchronization with the input of the characteristic selection signal SC. Therefore, the recording characteristics of the input video signal other than the reference signal R3 are not changed, and pass through the recording characteristics variable circuit 7 with the standard recording characteristics.

As a result, the recording characteristic variable circuit 7 outputs to the recording head 8 a recording signal C (see FIG. 2 (C)) having the reference signal R3 with changed recording characteristics in the horizontal scanning period of a specific vertical blanking period. , the signal C is recorded onto the magnetic tape 9 by this recording head 8.

The signal recorded on the magnetic tape 9 by the recording head 8 is immediately reproduced by the reproducing head 10. here,
3 shows the recording head 8 and the reproducing head 10 provided on the rotary cylinder 11, and FIG. 4 shows the recording head trace 13 and the reproducing head trace 14 on the recording track 12 of the magnetic tape 9.

The reproduction signal d shown in FIG. 2(d) outputted from the reproduction head 10 is supplied to a characteristic determination circuit 86.

In this characteristic determination circuit 6, the characteristic of the reference signal R8 in the reproduction signal d is determined at the timing of the reproduction switching signal e indicating the portion where the reference signal R3 is written, and the determination output signal D
O is supplied to the detection control circuit 5.

The detection control circuit 5 determines whether the recording characteristics of the reference signal R8 in the recording signal e are appropriate based on the determination output signal DO, and sequentially changes the characteristic selection signal SC until the appropriate recording characteristics are obtained. It is output to the recording characteristic variable circuit 7. As a result, characteristic detection is repeatedly performed in the detection control circuit 5 until the optimum recording characteristic is obtained.

Once the optimum recording characteristics suitable for the magnetic tape 9 have been determined, the recording characteristics variable circuit 7 is controlled so that portions other than the reference signal R3 can be changed to the same recording characteristics, and the input signal is changed according to the recording characteristics suitable for the magnetic tape 9. Video signal a is recorded.

Note that when determining whether the recording characteristics are appropriate or not in the characteristic determining circuit 6, if an abnormality of the magnetic tape such as a dropout occurs, the determination result is discarded and a new reference signal R8 is generated.
The characteristic determination circuit 6 and the detection control circuit 5 may be provided with a function that can prevent erroneous detection due to dropout or the like by performing characteristic determination without recording.

Further, after the optimum recording characteristic is selected, the recording characteristic variable circuit 7 records the input video signal a with this recording characteristic.
By gradually changing the recording characteristics when changing the characteristics, it is possible to prevent sudden changes in the playback screen from occurring.

〔Effect of the invention〕

As explained above, according to the present invention, recording characteristics suitable for a magnetic tape can be determined during the vertical blanking period that does not affect the reproduced image. There is no need to erase the recording characteristics, and recording characteristics can be selected during normal recording.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus according to the present invention, FIG. 2 is a waveform diagram showing the operation of the magnetic recording/reproducing apparatus of FIG. 1, and FIG. 3 is a diagram showing the operation of the magnetic recording/reproducing apparatus of FIG. FIG. 4 is a diagram showing the arrangement position of a reproducing head, FIG. 4 is a diagram showing a recording head and a race, a reproducing head and a race on a magnetic tape, and FIG. 5 is a block diagram showing the configuration of a conventional tape selector function. 2...Input switching circuit 3...Switching signal generation circuit 4
... Reference signal generation circuit 5 ... Detection control circuit 6 ... Characteristic judgment circuit 7 ...
- Recording characteristic variable circuit 8... Recording head 9... Magnetic tape 10...
・Reproduction head 11...Rotating cylinder 12...
Recording track 13... Recording head trace 14...
...Playback head trace a...Input video signal b...Recording switching signal C.
...Recording signal d...Reproduction signal e...Reproduction switching signal vS...Vertical synchronization signal R3...Reference signal SC...Characteristic selection signal DO...Characteristic judgment signal

Claims (1)

[Claims] A reference signal generation circuit that generates a reference signal; a switch circuit that inserts the reference signal output from the reference signal generation circuit into a specific vertical blanking period of an input video signal; A recording characteristics variable circuit that changes the recording characteristics of the reference signal portion of the output video signal; a recording head that records the video signal output from the recording characteristics variable circuit onto a magnetic tape; and a recording head that records the video signal output from the recording characteristics variable circuit onto a magnetic tape; a playback head for immediate playback; a property determination circuit for determining whether the recording characteristics of the reference signal in the playback video signal output from the playback head are compatible with the magnetic properties of the magnetic tape; and the recording property variable circuit. The recording characteristics are sequentially varied so that when the optimum recording characteristic is selected based on the judgment output signal of the characteristic judgment circuit, the input video signal is recorded on the magnetic tape using this optimum recording characteristic. A magnetic recording/reproducing device comprising: a control circuit that controls a variable circuit.