JPS58104584A - Video signal recorder and reproducer - Google Patents

Abstract

PURPOSE:To attain a reproduced picture without noise, by selecting larger output signal out of the signals of two rotary magnetic heads at the selection of a special reproduction mode. CONSTITUTION:Outputs of rotary magnetic heads 1, 2 are applied to a changeover switch circuit 5 via amplifiers 3, 4. The output of the circuit 5 is applied to a coding circuit 7, a storage device 8 and a comparator 9 through a reproducing signal processing circuit 6. The comparator 9 inputs a signal of the circuit 6 in synchronizing with the polarity of a switching signal A and selects a larger signal inputted during positive and negative period. When the positive signal A ios selected, a timing control circuit 10 stores the output of the circuit 7 to the storage device 8 during this period and outputs the output of the circuit 6 via a changeover switch 13. The data of the circuit 8 stored during the positive period is outputted via the switch 13 at the negative period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal recording and reproducing apparatus (hereinafter referred to as VTR) using a tilt azimuth recording method.

During conventional VTRd steel playback and slow motion playback using two-magnetic head helical scanning with an inclined azimuth recording method, the rotating magnetic head traces across 52 adjacent recording tracks, causing noise at the seam of the screen. There was a problem that occurred.

Furthermore, in order to solve the above problem, there is a method in which a playback head dedicated to still playback is provided between the rotary heads for the Eirin signal, and the dedicated playback head is used to trace the recording track during still playback.

Also, the position of the playback head on the head cylinder,
There is a control method in which the reproducing head tracks and traces one recording track.

The purpose of the present invention is to provide a video signal recording and reproducing device for FI and VTRs that uses electrical means, rather than mechanical processing means, to generate noise on the screen, which is different from the above. .

The present invention will be explained below using examples.

Figure 1 shows an embodiment of the present invention! It is a lock diagram.

#I1 In the diagram, 1 and 2 are rotary magnetic heads for recording and reproducing video signals, and the gap angles of the rotary magnetic heads 1 and 2 are set at 6 to 7 degrees in different inclination directions, respectively. The device is configured to perform oblique azimuth recording. Preamplifiers 3 and 4 amplify the output signals of the rotary magnetic heads 1 and 2, respectively. Reference numeral 5 denotes a changeover switch circuit for switching the outputs of the preamplifiers 3 and 4. The selector switch circuit 5 is alternately switched, for example, by a 30 Hz switching signal A supplied from the head cylinder closing circuit. The output from the changeover switch circuit 5 is reproduced by a reproduction signal processing circuit 6 and output as a video signal. The rotating magnetic heads 1 and 2, preamplifiers 3 and 4, selector switch circuit 5, and reproduction signal processing circuit 6 are constructed in the same manner as in the case of a normal two-rotating magnetic head helical scan type VTR.

The output of the reproduced signal processing circuit 6 is stored in a storage device 8 through an encoding circuit 7 that converts the output into PCM. on the other hand,
The output of the reproduced signal processing circuit 6 is configured to be input to a comparator 9 which compares the level of the Eirin signal of each channel in synchronization with the switching signal A to select the channel with the higher input level. be.

On the other hand, 10 is a timing control circuit, which inputs the output of the comparator 9 and the switching signal A, and controls the period of the switching signal A corresponding to the channel selected by the comparator 9.
The output of the encoding circuit 7 is sequentially stored in the channel, and the contents of the storage device 8 are read out sequentially during the period of the switching signal A corresponding to the channel not selected by the comparator 9. Reference numeral 11 denotes a decoding circuit having an A-74 filter at the output stage, which decodes the data read from the storage device 8 and returns it to the Eirin signal.13 indicates the output Eirin signal of the reproduction signal processing circuit 6 and the still reproduction signal. This is a changeover switch circuit which receives as input the output signal of the decoding circuit 11 through the switch circuit 12 which is turned on during special playback such as slow-motion playback. The changeover switch circuit 13 receives the timing control circuit 1°O signal which is not selected by the comparator 9 and is outputted during the period of the switching signal A of the 9th channel, and the decoding circuit 11 which is outputted via the switch circuit 12t. The configuration is such that the output is selected and output.

In the nine embodiments constructed as described above, the switch circuit 12 is in the OFF state during standard moderate playback, and the selector switch circuit 13 is switched to the position shown in FIG. The changeover switch circuit 5 is alternately switched by the changeover signal M), and the preamplifiers 3 and 4 amplify the output signals of the nine-rotation magnetic heads L and 2, respectively, as playback signals! Alternately output to the 6-ring circuit 6. Playback signal processing WAl
&@ is input through the changeover switch circuit 5, and the output signals of the nine device amplifiers 3 and 4 are regenerated into a video signal and outputted through the changeover switch circuit 13.

Next, a case where the playback mode is changed to still playback KfJ will be explained.

When switching to steel regeneration, the magnetic wheel stops running. Further, the switch Iljl1m is in the on state since the special playback mode is selected. However, although the inclination of the recording track on a magnetic tape changes as the grasshopper tension changes, the rotating magnetic heads 1 and 2 run on the magnetic tape in the same way as during recording, and the traveling locus of the rotating magnetic head and the recording track change. The relationship between
As shown in FIG. 1, the inclination angles are different, and as shown in FIG. 2, the traveling locus of the rotating magnetic head straddles two recording tracks.

In Figure 2 (,), 1□ and 1. indicates the recording track by the rotary magnetic head IVC, 2□ and 21 indicate the recording track by the rotary magnetic head 2, and the broken line 20 indicates the traveling locus of the rotary magnetic head 1 and 20 during steel reproduction.

As is well known, the broken line 20 and the recording track IA
The recording signal in the portion B where the broken line 20 overlaps with the recording track 21 is sufficiently picked up by the rotating magnetic head 1, but the recording signal in the portion C where the broken line 20 and the recording track 21 overlap is picked up by the rotating magnetic head 1 due to azimuth loss. Similarly, the recorded signal in portion C is sufficiently picked up by the rotating magnetic head 2, but the recorded signal in portion B is not sufficiently picked up by the rotating magnetic head 2.

On the other hand, the position at which the magnetic tape stops running according to the still play command is not uniquely determined, and the areas of the portions B and C are usually different. Now, hypothetically, the area of part B is part C.
Assume that the area is larger than the area of .

FIG. 2(b) is a reprint of the switching signal A. During the positive period of the switching signal A, the output of the preamplifier 3 which amplified the output signal of the rotating magnetic head 1 is selected, and the negative It is assumed that during the period , the output of the preamplifier 4 which amplified the output signal of the rotating magnetic head 2 is selected and outputted from the changeover switch circuit 5.

Therefore, the comparator 9 inputs a signal obtained by sampling and holding the output level of the reproduction signal processing circuit 6 during the positive period of the switching signal A in synchronization with the rising edge of the switching signal A, and synchronizing with the falling edge of the switching signal A. A signal obtained by sample-holding the output level of the reproduced signal processing circuit 6 during the negative period of the switching signal A is inputted, and the magnitude of the input is compared to select the one corresponding to the user. Since it is assumed that the area of portion B is large as described above, the positive period of the switching signal A is selected by the comparator 9. The tying control circuit 10 encodes the output signal of the reproduced signal processing circuit 6 during the positive period of the sand switching signal A according to the output of the comparator 9, and stores the output of the friend encoding circuit 7 in the storage device 8. , selector switch 1
3 to the contact position shown in FIG. 1 to select the output of the reproduction processing circuit 6. Further, during the subsequent negative period of the switching signal A, the timing control circuit 10 outputs the contents of the storage device 8, and also outputs the contents of the storage device 8 during the negative period of the switching signal A. The output from 11 is selected and output.

Therefore, during the positive period of the switching signal A, the output signal of the rotating magnetic head 1 is amplified, and the output of the reproduction signal processing circuit 6 based on the good signal is outputted via the changeover switch 13, and during the negative period of the switching signal A, The data stored in the encoding circuit during the positive period of the previous switching signal A is decoded by the decoding circuit 11, and the signal that becomes the Eirin signal is sent to the changeover switch circuit 1.
3, and one frame of screen is formed by both outputs. In order to repeat the above steps in the same way during the still playback period, the image is projected without noise on the screen, and even in the case of fast-moving images, the image does not appear blurry.・Although the above description has been made for the case where the area of portion B is larger than the area of portion C, the same applies when the area of portion l is smaller than the area of portion C. In this case, the above-mentioned rotating magnetic head Instead of the output of the rotary magnetic head 1, the output of the rotary magnetic head 2 is amplified and a signal reproduced by the reproduction signal processing circuit 6 is output during the switching signal period, and the same signal is output from the decoding circuit 11 as the switching signal. will be output during subsequent positive periods of the period.

In addition, the comparator 9 compares the output level of the reproduced signal processing circuit 6 during the positive period and the negative period of the switching signal M, and compares the size of the area of the portion 10 and the area of the portion C. The positive period or negative period of the switching signal M corresponding to the larger one is selected, and 1. (
1 field + jl +...) and time t, (tm, t...)
), and in this case, Figure 2(a) K
As shown, the dashed line 0. The areas of portions B and C after the point in time when the rotary head 1.2 passes through the direct hit portion shown in FIG.

In addition, the time τ is increased and the one-point chain binding is shown in Figure 3 and Figure 4.
Parts B and C after the rotating heads 1 and 2 pass through the rose part
You can also compare the areas of

Furthermore, during a period in which the special playback mode is not selected, the switch circuit 12 is turned off, so that the encoding circuit 7, the storage device 8, the comparator 9, the timing control circuit 10, and the decoding circuit 11 is irrelevant, and the changeover switch circuit 13 is switched to the output end side of the reproduction signal processing circuit 6, so that it does not affect the standard speed reproduction.

The above description takes the case of steel regeneration as an example, and the same applies to the case of slow motion regeneration.

Note that although the storage device 8, the encoding circuit 7, and the decoding circuit 11 are used in the above embodiment, a similar configuration can be made by using a delay means in place of these.

As explained above, according to the present invention, noise is not superimposed on -1 during special playback such as motion playback using a helical scanning method using a two-rotation magnetic head.
Since the -1's that make up the frame are the same, there is no chance that the -1's will be blurred.Also, since the screen of both odd and even fields can be seen, detailed still slow motion images can be seen. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2(a) and (Koji are schematic diagrams showing recording tracks and traveling trajectories of a rotating magnetic head and switching signal waveform diagrams for explaining the operation of an embodiment of the present invention. 1 and 2... Rotating magnetic head , 3 and 4... preamplifier, 5 and 13... changeover switch circuit, 6.
... Reproduction signal processing circuit, )... Encoding circuit, 8...
Storage device, 9... Comparator, 10... Timing control circuit, 11... Decoding circuit, 12... Switch circuit. Nobuo Sunako, Patent Attorney, Patent Attorney, Patent Applicant, Leading Company, Trio

Claims (1)

[Claims] In a video signal recording and reproducing apparatus that has first and second rotating magnetic heads and uses a magnetic head helical scanning inclined azimuth recording method, when a special playback mode is selected, the output signal of the first rotating magnetic head is The reproduced video signal is outputted and the video signal is stored, and when the output signal of the second rotary magnetic head is reproduced, the output signal of the second rotary magnetic head is stored in place of the reproduced video signal. 1. A video signal recording/reproducing device characterized in that the video signal recording and reproducing device is configured to output a video signal obtained by reproducing an output signal of a first rotating magnetic head.