JPH0250523B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus that leaves less unerased data when performing splicing and inserting on a home VTR.

Splicing/inserting in a VTR involves erasing the previous signal by overwriting a new signal on the already recorded track, and leaving the previous signal unerased becomes a problem.

As a solution to this problem, broadcast VTRs use a flying erase head that completely erases the previous signal before recording a new signal.
However, the flying erase head is an erase-only head, has poor cost performance, and is suitable for home use.
This had become difficult to use in VTRs.

The purpose of the present invention is to
It is an object of the present invention to provide a magnetic recording and reproducing device which can improve the conventional problem of unerased parts when inserting and enables high-quality reproduction with less unerased parts.

The present invention improves the unerased area during splicing and inserting by increasing the recording current, and suppresses the sideband enhancement due to increased current by suppressing the sideband and increasing the current to prevent the reversal phenomenon. It is characterized by

FIG. 1 shows the characteristics of the erasing signal with respect to frequency. What becomes a problem as unerased signals are low-frequency color components, which appear as interference on the screen. In order to improve this, if the recording current for overwriting is increased, the erasing rate increases as shown in FIG. 2, and therefore, by increasing the recording current, the unerased color component can be greatly improved.

Further, FIG. 3 shows the erasing characteristics of color components when the gap length (track width) of the recording head is changed. Note that this is a case where the recording current and the erasing current are made equal. In this way, by widening the gap length, unerased color components can be improved.

The present invention was invented based on such properties, and will be explained below with reference to Examples.

FIG. 4 shows an embodiment showing the basic configuration of the present invention.

First, normal recording will be explained. A luminance FM signal is input from an input terminal 1 and a color signal is input from an input terminal 2, and these signals are mixed by a Y/C mixer 3. During normal recording, the insert control signal 8 is not input, the changeover switch 7 is connected to contact a, and the recording signal is input directly from the Y/C mixer 3 to the recording amplifier 5. The signal is amplified by a recording amplifier 5, and a recording current flows through a recording head 6. The recording current frequency characteristic during normal recording is shown by the solid line in FIG.

Next, we will explain how to perform continuous shooting and inserting.

The luminance FM signal and color signal mixed by the Y/C mixer 3 are input to a chiral peaking circuit 4. The carrier peaking circuit 4 applies peaking to the FM carrier only around 4MHz, as shown by the dotted line in FIG. 5, and increases the current while suppressing sidebands. At the time of insertion, the insert signal 8 is input and the changeover switch 7 is connected to contact b, so that a recording current with sidebands suppressed is output from the recording amplifier 5 and flows to the recording head 6.

FIG. 6 shows an example of a specific circuit of the carrier peaking circuit 4 and the changeover switch 7. During normal recording, the insert control signal 16 is not input and the transistor 10 is turned off. Therefore, the signal input from the base of transistor 9 is transmitted through resistors 11 and 1.
2 and output. The frequency characteristics at this time are represented by the solid line in FIG.

An insert control signal 16 is input to the overwriting, the transistor 10 is turned on, and emitter peaking is operated by the resistor 13, capacitor 14, and inductance 15. Therefore, the output current frequency characteristic becomes as shown by the dotted line in FIG. 5, and only the current at a specific frequency can be increased. The insert control signal 8 is always kept at a high potential to turn on the transistor 10 during the insert mode, but in the edit mode, it is kept at a high potential only during the first overwriting period, and then the normal recording state is resumed. Return to.

Incidentally, as a side effect of carrier peaking, some S/N deterioration and resolution deterioration occur, but this does not pose a particular problem since it is only for a short period of time in the insert or edit mode.

FIG. 7 shows a track pattern on a tape when the track width T _w (=head width) is narrower than the track pitch T _p . In this case, since the track width T _w is narrower than the track pitch T _p , a guard band of T _p -T _w occurs between the track patterns. 20 indicated by a broken line is a track pattern that has already been recorded, and 21 indicated by a solid line is a track pattern to be overwritten at the time of splicing or inserting. If the overwritten track pattern 21 deviates from the recorded track pattern 20, the previous signal in the shaded area remains and may be reproduced together with the overwritten signal during playback.
This causes a problem in that beats between FMs and chroma signals remain unerased. A specific embodiment of the present invention for improving this problem is shown in FIG. track width
Since T _w is wider than the track pitch T _p , a guard band between track patterns as shown in FIG. 7 does not occur. Therefore, overwriting track pattern 2
4 deviates from the recorded track pattern 23, only the overwritten signal is recorded on the tape, so only the new signal resulting from the overwriting is reproduced.

As described above, by using the present invention, the problem of unerased images during splicing and inserting can be improved by using a simple circuit called a carrier peaking circuit.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the frequency characteristics of previous signal erasure by overwriting, Figure 2 is a characteristic diagram showing the erasing characteristics (color component) of the previous signal when the overwriting recording current is changed, and Figure 3 is a characteristic diagram showing the erasing characteristics (color component) of the previous signal when the overwriting recording current is changed. A characteristic diagram showing the erasing characteristics (color component) when the recording head cap length is changed,
FIG. 4 is a block diagram showing the basic configuration of an embodiment of the present invention, FIG. 5 is a characteristic diagram showing an example of carrier peaking characteristics used in the present invention, and FIG. 6 is a circuit showing a specific example of a carrier peaking circuit. 7 is a plan view showing a recorded pattern on the tape when the track width is narrower than the track pitch, and FIG. 8 is a plan view showing an example of the recorded pattern on the tape when the present invention is used. 3...YC mixer, 4...carrier peaking circuit,
5... Recording amplifier, 6... Recording head, 7... Selector switch.

Claims (1)

[Scope of Claims] 1. Mixing means for mixing a signal obtained by angle modulating a video signal and a signal obtained by converting a video color signal into a low band so that the carrier wave has a frequency lower than the angle modulation band of the video signal; In a helical scan VTR, which is equipped with an amplifying means for amplifying the recorded signal and a magnetic head for recording the recorded signal on a recording track on a magnetic tape, the recording signal is superimposed on the track on the magnetic tape on which the signal has already been recorded. Magnetic recording characterized by comprising a carrier peaking circuit that increases the recording current near the carrier wave of the recording signal compared to the recording current when recording the signal on a magnetic tape on which no signal is recorded. playback device. 2. In claim 1, the recording head is a first head used during non-overlapping recording;
A second magnetic head having a wider recording track width than the first head is provided, and when a recording signal is to be recorded on a track on which a signal has already been recorded on the magnetic tape, the recording signal is recorded by the second head. A magnetic recording/reproducing device characterized in that a recording signal is recorded on the magnetic tape.