JPS58154986A - Magnetic video recorder and reproducer - Google Patents

Abstract

PURPOSE:To improve the isolation between a recording signal and a reproducing signal and to attain a specified performance for the control of height of a video head at recording, by incorporating a reproducing amplifier to amplify a reproduced output of the video head in a rotary cylinder. CONSTITUTION:At reproduction, all switchs 8 are connected in the opposite position in figure. The reproducing signal from the video head 10 is amplified at the reproducing amplifier 12 incorporated in a rotary clinder the same as the video head and connected with the head with very short leads, and outputted to an output terminal 13 via a rotary transformer 9. The reproducing signal is split corresponding to the position on a magnetic tape of the video head 10 and given to a processing circuit of each signal. When the video head 10 is positioned on a blank part 5 at the preceding recording, only the channel is reproduced and the flow of the reproducing signal for the case is the same as that at the reproduction. Thus, the isolation is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus (hereinafter abbreviated as VTR).

As is well known, general VTRs are mainly of the two-head helical scan type, in which two video heads mounted on a rotating cylinder alternately scan a magnetic tape wound around the cylinder at an approximate 18° angle. and record and play back the signal. Furthermore, signals are exchanged between the rotating video head and the recording/reproducing signal processing circuit via a rotary transformer, and there is no signal processing circuit on the rotating cylinder.

Recently, newly developed recording technology and video head tracking technology are being applied to VTRs, and while these technologies bring great advantages, they also create new problems. First, I will briefly discuss these.

One of these is a technique in which an audio signal is frequency multiplexed with an FM modulated signal and a recording number 10 of a blank video and recorded on the same video track by a video head. (A known example is Japanese Patent Publication No. 39-9565.) This is less susceptible to mechanical wow and flutter, provides good reproduced sound with little frequency fluctuation, and provides rich reproduced sound with a wide transmission frequency band. On the other hand, this is due to dropouts in the playback signal. There are problems in that instantaneous noise is likely to occur, and post-recording (re-recording only the audio signal while leaving the video signal unchanged) is not possible.

In addition, the magnetic tape is wound around a rotating cylinder 200 to 2200 times, and an overlap section is provided on the extension of the video track, which is formed during the period when two video heads scan the magnetic tape at the same time. There is also a proposal to record the audio signal with a video head. Since this overlapping portion exists discontinuously in time, the signal must be compressed once in the time axis. (A known example is Japanese Patent Publication No. 53-2724.) In this case, since the signal is recorded at a location different from that of the video signal, dubbing becomes possible. Of course, I thought this was only for dubbing, and the previous F
It is also possible to coexist with M modulation multiplex recording.

In order to improve the tracking accuracy of the video head, this is mounted on an electrostrictive element such as a bimorph plate, and during playback, control No. 1g is applied to the electrostrictive element so that the video head accurately traces over the recording track. A technique has also been developed.The control signal is also obtained from a pilot signal frequency multiplexed to the video track, but since it is already well known, the details will be omitted. (A well-known example is the Philips VTR V-2000 model.) Furthermore, there is a proposal to control the height of the video head using this electrostrictive element also during recording.

In other words, adjusting the heights of two video heads simply by adjusting the screws is a difficult task, and the heights of the two video heads may become distorted over time. Therefore, an attempt is made to control the recording time so that it always matches.

Specifically, each track formed diagonally on a magnetic tape records only a signal of a specific frequency for a length of about 1 to 2 thousand cycles of the video signal, and then When one video head is recording an adjacent track, when it comes to a position adjacent to the recording area of the signal, the signal circuit system of that channel is switched to the playback mode, and the signal from the adjacent track is recorded. After reproducing the signal, the circuit system is immediately switched to the recording mode, and a recording portion of the signal is also formed for 1 to 2 thousand cycles on the track being formed. (In addition,
The timing of recording and reproduction is reversed depending on how the track is formed. ) By repeating this operation and applying a control voltage to the electrostrictive element so that the playback output of No. 16 of both video heads is equal (or both are zero), the height of the two video heads can be reduced. Although it is convenient that the height can be adjusted each time recording is performed, there are two major problems with this height control during recording. One is F, which is multiplexed onto the video track.
This is interference to the M-modulated audio signal. There is no recording of video, audio, etc. not only in the portion where the signal circuit is switched to the instantaneous reproduction mode but also in the height control signal recording portion. Therefore, if this portion is in a portion where a video signal and a FIVI modulated audio signal are multiplexed and recorded, these pieces of information will repeatedly undergo a momentary dropout phenomenon during playback.

For video signals, it is possible to prevent them from appearing on the TV screen by placing them in a vertical blank period, but such measures are not possible for audio signals, and significant noise may occur in the reproduced sound. There is a problem in that it causes

The second problem is as follows. I mentioned that one video head performs a momentary playback operation during recording, but
It is not always possible for the other video head to perform the reproducing operation at the same time. In other words, as mentioned above, there are currently some video heads that perform overlapping recording by wrapping the magnetic tape over 180 degrees around a co-rotating cylinder. In this case, two video heads may be on the magnetic tape, and if they are played back at the same time, a completely meaningless dropout period will be created in areas other than the height control signal recording portion. The other video head must therefore continue recording. Toko,
(Generally, the reproduced signal is about 80 dB smaller than the recorded signal.) If these exist at the same time, the reproduced signal will be severely disturbed and will not be able to perform its original function. In order to achieve isolation of 5 OrlB or more between two electrical systems, careful consideration must be given to their arrangement, but in this case, it is only 80rlB that allows the playback signal and recording signal leakage to be equal. However, the problem is that it is difficult to fully achieve the intended purpose.The purpose of the present invention is to An object of the present invention is to provide a method and means for solving problems in performing height control, eliminating interference with audio signals caused by this, and eliminating interference caused by height control signals during playback from a practical point of view. In other words, by first recording and reproducing the height control signal at a position other than the part where the video signal and the audio signal as an FM modulated wave are recorded, interference to the audio signal is eliminated, and the recording and reproducing signal circuit is By incorporating at least a regenerative amplifier into the rotating cylinder to amplify the reproducing output of the video head, it is possible to improve the isolation between the recording signal and the reproducing signal, and to control the height of the video head during recording. The aim is to make it possible to perform according to the performance of the period.

Next, embodiments of the present invention will be described with reference to the drawings. 1st
FIG. 2 illustrates a part of the recording pattern that remains on the magnetic tape when the present invention is implemented. 1 is a magnetic tape, and 2 is a video trunk in which a video signal and an FM modulated audio signal are frequency-multiplexed recorded. 3 is hereinafter referred to as an overlap track. This is a track that is an extension of the video track 2 and is created by winding the magnetic tape 1 around a rotating cylinder more than 180 times.
For example, digitized audio signals are recorded. Reference numeral 4 indicates a recording portion of a signal for controlling the height of the video head during recording, and reference numeral 5 indicates a blank portion generated by reproducing this height control signal by the m-video head during recording.

The first problem mentioned above, that is, interference with the FM modulated audio signal by recording and reproducing the height control signal, is achieved by making the recording turns on the magnetic tape as shown in Figures 1 and 2. This can be solved by That is, the recorded portion of the height control signal 4. In other words, the blank portion 5 can be positioned either inside the lap track 3 (Fig. 1) or adjacent to the boundary between this and the video track 2 (Fig. 2).In other words, the video track 2 It would be better to locate it somewhere else. Of course, you can set this location as you like. Also, since overlap track 6 originally records No. 16, which has been compressed on the time axis, there is no problem at all even if part of it is occupied by numbers 4 and 5, and interference can be prevented by changing the compression method. You can essentially avoid being affected. -Next, I will explain how to solve the second problem, which is that it is difficult to instantaneously reproduce the height control signal of the video head due to the problem of isolation from the recording signal applied to one video head. First, let's consider why isolation deteriorates.

The isolation between the two video heads in current VTRs is partly due to circuit elements, but it is more essentially due to the wires and rotary transformers that connect the video head and the signal recording/reproducing circuit. 0, that is, electromagnetic coupling between the wires and magnetic coupling between both channels of the rotary transformer. However, the former can be improved by making the wires shorter, especially the wires between the video head and the regenerative amplifier. (There is a rotary transformer for inch VTRs) This can be improved from the current situation 0 If the problem becomes serious because the playback signal level is originally much lower than the recording signal level, as in the example above, the playback signal should be changed to the recording signal level. If the signal is amplified to approximately the same level as the signal and then passed through the rotary transformer, there will be no problem at all.

Therefore, in the present invention, in the signal recording and reproducing circuit, at least a reproducing amplifier for amplifying the reproduced signal from the video head is built into the rotary cylinder. The wire can be made extremely short, and the weak reproduction signal is amplified by the reproduction amplifier and then applied to the rotary transformer, so the above-mentioned isolation problem is eliminated and the height of the video head can be stably controlled during recording.

FIG. 6 is a circuit block diagram showing an embodiment of the present invention described above, in which 6 is an input terminal, 7 is a recording amplifier, 8 is a recording/reproduction changeover switch, 9 is a rotary transformer, 10 is a video head, and 11 is a magnetic 12 is a reproducing amplifier, and 13 is an output terminal.

During recording, different types of signals are input to the input terminal 6 depending on the position of the video head 10 on the magnetic tape 11. That is, when the video head 10a is at the position of the height control signal recording portion 4 of the video head among the overlap tracks 3 shown in FIGS. 1 and 2, the signal is For example, a digitized audio signal is input from the input terminal 6a. When located at the video track, a frequency multiplexed signal of a video signal and an FM modulated audio signal is input from the input terminal 6a. The relationship between the position of the video head iob and the input signal of the input terminal 6b is also the same.
and recording amplifier 7. Switch 8. rotary transformer 9
is connected to the video head 10 via a magnetic r-op 11.
The information is recorded as shown in FIGS. 1 and 2 above.

On the other hand, during playback, all the switches 8 are connected in the opposite direction to that shown. The playback signal from the video head 10 is
A regenerative amplifier 1 is built on a rotating cylinder like the video head and connected to it via an extremely short wire.
After being amplified by step 2, the signal is output to output terminal 15 via rotary transformer 9. After this, the playback signal is
Needless to say, the signal is divided according to the position of 0 on the magnetic tape and sent to each signal processing circuit. Figure 1 at the time of the previous recording.

When the video head 10 is located in the blank area 5 in FIG. 2, only that channel is reproduced, but the flow of the reproduced signal at this time is the same as in the above-mentioned reproduction.

It will be clear that if this is done, the above-mentioned iso-unique problem will disappear.

Although the electrostrictive cable on which the video head 10 is mounted is omitted in FIG. 3, the present invention is based on the presence of this cable.

Similarly, in Fig. 6, the case where only the reproducing amplifier circuit (or a part of this circuit) is built into the rotary cylinder is explained as an example, but if necessary, a recording amplifier or other signal processing circuits may also be built in along with it. In this case as well, the same effect as in the above embodiment can be achieved.

Furthermore, FIG. 4 shows another embodiment different from that shown in FIG.

Here is the rotary transformer 14. The components other than the regenerative amplifier 15 at the rear stage may be the same as those shown in FIG. In other words, if the recording system and playback system are further separated and a 4-channel rotary transformer 14 is used, only two selector switches 8 are required. This is added when the signal processing circuit is insufficient to operate satisfactorily. If it is unnecessary, it can be omitted, and the gain of the regenerative amplifier 12 can be further increased.
It is also possible to have this function.

As explained above, the present invention provides a signal for controlling the height of a video head mounted on an electrostrictive element during recording.
The idea is to record and reproduce information using a video head at a position other than the video track, and to incorporate at least a reproduction amplifier in the recording and reproduction signal circuit into a rotary cylinder.

Therefore, interference of the height control signal with respect to the FM modulated audio signal recorded on the video track can be completely eliminated. Further, when the height control signal is instantaneously reproduced, the interference of other signals to the reproduced signal can be much reduced compared to the conventional method, and there are effects such as excellent video head height control.

[Brief explanation of the drawing]

1 and 2 are recording pattern diagrams on a magnetic tape when the present invention is implemented, FIG. 3 is a circuit block diagram showing an embodiment of the present invention, and FIG. 4 is a diagram showing another embodiment of the present invention. It is a circuit block diagram showing. 2... Video track 3... Omni lap track 4... Height control signal recording section 5... Blank section 9... Rotary transformer 10... Video head 1'2... Reproduction amplifier 1.11...Magnetic tape 14...Rotary transformer sound 1 diagram! Droplet 2

Claims (1)

[Claims] A video head records at least a video signal and an audio signal as an FM modulated wave on a video track of a magnetic recording medium, and the video head records, for example, time-base compressed and digitized audio on a track extending from the video track. The video head is mounted on an electrostrictive element so that the height position of the video head can be controlled, and there is also a control system for optimizing the height position of the video head during recording. In a magnetic recording and reproducing device that records a video signal at any position of the track with a video head, the video signal and the VCF M modulated wave are used as the signals for controlling the height position of the video head. A reproducing amplifier or a part thereof for recording and reproducing at a position other than the video track where the audio signal is recorded and at least amplifying the reproduced signal from the video head is built into the rotating cylinder on which the video head is mounted. A magnetic recording and reproducing device with a % characteristic.