JPS62264783A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a variable speed reproducing picture without noise by using a means switching at least one set of double azimuth head pairs at high speed depending on the detection of an output level and obtaining a continuous reproducing signal and a picture storage device for one field. CONSTITUTION:When a CH1 is traced on a magnetic tape, a signal SW 30 goes to a low level and when a CH2 is traced, the switch SW 30 goes to a high level. The channel is selected by the operation of a chageover switch 9. The outputs of heads 1,2 are amplified by preamplifiers 4, 5 in the operation of the channel CH 1, and fed to a changeover switch 8. A head switching control circuit 7 detects an envelope of an output of the preamplifiers 4, 5 to generate a switching signal for the head selection. In the CH2 period next, the changeover switch 9 is operated and a signal being the result obtained by amplifying the output of a head 3 by a preamplifier 6 is selected. A TV signal demodulated by a signal processing circuit 10 is fed to an A/D converter 11 of the next stage, where the signal is converted into a digital signal and a picture for one field is stored in a memory 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording and reproducing device using memory,
In particular, the present invention relates to a control method suitable for obtaining good reproduced images during variable speed reproduction.

[Prior Art] In a helical scan type magnetic recording/reproducing device, in a variable speed playback mode in which the magnetic tape is run at a speed different from that during recording, the trace pattern of the magnetic head is different from that during recording, so generally the trace pattern on the screen is different from that during recording. Noise occurs. In the conventional apparatus, a screen with little noise was obtained by various means. For example, a method for obtaining a good image in a high-speed reproduction state is described in Japanese Patent Laid-Open No. 58-83490. This is a head pair consisting of two magnetic heads with different azimuth angles (hereinafter referred to as a double azimuth head pair).
By using two sets of magnetic heads and selecting the head with the highest reproduction output from among the four magnetic heads in a high-speed reproduction state, a noise-free image can be obtained.

Next, this prior art will be specifically explained using drawings.

FIG. 5 is an example of a rotating cylinder configured to improve high speed reproduction images. Both the C84 side and CH2 side are each composed of a pair of double azimuth heads, with 17
is the CHI side + azimuth head, 18 is the CHI side - azimuth head, 19 is C1 (2 side + azimuth head, 20 is C) (2 side - azimuth head.Here, head 17
and head 20 are used for normal recording and playback in standard mode,
Het I I! , head 17 is 58 μm, head 20
is 40 μm. Head 18 and head 19 are used for normal recording and playback in long-time mode, and both head widths are 30 mm.
It is μm. Further, the heads 17 and 20, as well as the heads 18 and 19, are each mounted at a position of 180@jL, and the interval between the two heads of the double azimuth head pair is set to 370 μm. Figure 6 is
5 shows a track pattern of a magnetic tape recorded using the cylinder of FIG. (a) is a recording pattern in standard mode, and (b) is a recording pattern in long-time mode. Now, when the magnetic tape is run at a higher speed than during recording, the slope of the head running trajectory changes from that during recording, and the head travels across a number of tracks corresponding to the speed. At this time, if you play back using the same head that was used for recording, since the magnetic tape is recorded alternately with + and - azimuths, the playback signal will only be obtained intermittently, and the screen will appear on the screen. , some bar noise will occur. (b) In the case of long-time recording mode as shown in the figure,
Since the head width is wider than the track width, only thin bar noise appears, but in the standard recording mode shown in (a), the head width is narrower than the track width of 58 μm, and there is a non-recording band (girt band) on the pattern. Because of this, a wide bar noise appears on the screen.

The prior art improves high-speed reproduction images in the standard mode.For example, when a magnetic tape is run at three times the speed in the forward direction, the trajectory of the magnetic head is shown in FIG. A pair of double azimuth heads run on the magnetic tape.
Every half rotation of the rotating cylinder, the switches alternate between CHl and CH2, but when CHI, the head 17, 18, .
At the time of CH2, it is possible to obtain a continuous reproduction signal by selecting and outputting the head with a larger reproduction output among the heads 19 and 20. This situation is shown in FIG. (a) is the +azimuth head output envelope,
(+) indicates the envelope of the −azimuth head output. In this way, (,) and (b) have a complementary relationship, so by performing envelope detection and selecting the head with the larger output, a continuous signal as shown in (c) can be obtained. be.

Although it is possible to obtain a continuous signal during high-speed reproduction using the above principle, the running speed of the magnetic tape is limited to an odd number multiple speed during normal reproduction. This is due to the misalignment of the two heads in the double azimuth head pair. In other words, the head 18 outputs a signal temporally advanced by one horizontal scanning period (IH) to the head 17. this is,
The same applies to head 19.20. Therefore, among the reproduced outputs shown in FIG. 8(c), the C11l-azimuth head output and the C112+azimuth head output output images that are shifted by 111 minutes. However, when the magnetic tape speed is an odd number multiple of the normal speed, the 114 deviated portion as shown in No. 81;11(r,) is at almost the same position as CHI and CI (2? An image with no interlayers can be obtained.If CHI and CH2 output LH shifted signals, it will appear as a vertical shift on one screen, and that part will be vertically blurred. It looks like this.

[Problems to be Solved by the Invention] In the prior art described above, two double azimuth pairs are required to improve high-speed reproduction images in the standard mode. Such rotating cylinders have a complicated structure and the number of parts increases, and not only do they have to maintain an accurate spacing between the two heads in a double azimuth head pair, with the opposing heads each mounted at an index position of 180@. There were also manufacturing problems, such as the need for Furthermore, as mentioned above, there are also problems such as the limited running speed of the magnetic tape and the occurrence of thin bar noise in high-speed reproduction images in long-time mode.

An object of the present invention is to solve the above problems by using an image storage device for l fields.

[Means for Solving the Problems] Item 11 above is based on a rotary cylinder having at least one pair of double azimuth heads, and in a field where the pair of double azimuth heads traces a magnetic tape.
This is achieved by configuring a means for obtaining continuous reproduction signals by switching two heads at high speed using output level detection, etc., and a 1-field video signal storage device that can be constructed from a semiconductor memory or the like. be done.

[Function] When performing variable speed playback such as high-speed search using a rotary cylinder having a pair of double azimuth heads, in the field where this pair of heads traces the magnetic tape, continuous video signals are This can be obtained by head switching means.

Here, in this field, the video signal is output as is, and at the same time, in the field where the azimuth head pair does not trace the magnetic tape, the video storage device is switched to the read state. A continuous video signal before the field is output. As a result, the video output is always continuous, and it is possible to obtain a good variable speed reproduction image without noise.

[Example] Hereinafter, an example of the present invention will be described using the drawings. Here, we will use a VH8 helical scan type VTR as an example.
I will explain.

FIG. 1 is a block diagram showing an example of the system configuration of the present invention, and FIG. 2 shows the system configuration of FIG. 1.

An example of the cylinder head arrangement is shown. Here, l
is the +azimuth head on the CH1 side, 2 is the C) (one azimuth head on the l side, and 3 is the one azimuth head on the CH2 side.Heads 1 and 3 are normally used for recording and reproduction, and the head width is 30μ+n. The head 2 is used only in the variable speed playback mode and has a head width of 58 μm.Furthermore, the distance between the heads 1 and 2 is set to the recording wavelength of 370 μin for one horizontal scanning period on the magnetic tape.Furthermore, 4.
5.6 is a preamplifier, 7 is a head switching control circuit, 8, 9
．． 13 is a changeover switch, 10 is a signal processing circuit, 11 is A
/D converter, 12 is a memory circuit, 14 is a D/A converter,
15 is the SW30 signal input terminal.

16 is a video signal output terminal.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 and 4. FIG. 3 shows a track pattern on a magnetic tape recorded using heads 1 and 3 of the rotating cylinder shown in FIG. (,) is the standard recording mode pattern,
(b) is a pattern for long-time recording mode. This embodiment removes bar noise in standard recording mode.

Here, the operation will be explained by taking as an example the case of triple speed in the forward direction in FIG. (a) shows the trace pattern of the head, (b) shows the 5W30 signal, and (b) shows the reproduction envelope signal. Here, the SW30 signal indicates the phase of the - rotation cylinder, and the period during which the CHI side traces the 6 magnetic tapes generated in synchronization with the rotation is 120W, and the CH
The period during which the second side traces is HIG)1. This channel selection is performed by operating the changeover switch 9. First, regarding the operation during the CHI period, the output of the head 1.2 is amplified by the preamplifiers 4 and 5 and then applied to the changeover switch 8. The head switching control circuit 7 detects the envelope of the output of the preamplifier 4.5 and generates a switching signal that selects the head with a large envelope. , a continuous signal can be obtained. Next CH2
During this period, the signal obtained by amplifying the output of the head 3 with the preamplifier 6 is selected by operating the changeover switch 9. As a result, the output of the changeover switch 9 is as shown in Fig. 4-(b)-(b).
The signal that is partially missing on the CH2 side is applied to the signal processing circuit 10 and demodulated into a TV signal. The demodulated TV signal is applied to the next A/D converter 11 and converted into a digital ha signal.
The data is stored in the memory circuit 12.

The memory circuit 12 has the ability to store one field of image as a digital value, and the writing and reading of the memory circuit 11 is controlled by the SW30 signal input.

During the period when the 5W30 signal is LOW, that is, during the CHI period,
The memory circuit 12 performs a write operation, and the memory circuit 12 performs a write operation.
The continuous reproduction signal obtained by the switching operation in step 2 is held in the memory as stored information.

During the period when the SW30 signal is HIGH, that is, during the CH2 period, the memory circuit 12 performs a read operation and one field of image signal data held in the memory is output. Furthermore, the selector switch 13 is also S.
W 30 (switches at No. 8, CH
During the L period, the output of the )\/D converter 11 is directly converted to D/
Applied to the A converter.

In other words, from the output of the changeover switch 13, during the CHI period, the continuous video signal from head 1.2 is output in real time, and during the CH2 period, the video signal from the C11 period before the ■ field is output again. Become. This signal is D
/A conversion and becomes an analog TV signal again, so that a continuous video signal without bar noise is output to the video signal output terminal 16. The image obtained in this way is updated every two fields, so
The movement on the screen will be rough, but since high-speed playback is originally used for the purpose of inspecting the contents of magnetic tape, and the image movement itself is very fast, it is hardly noticeable. . Furthermore, since images reproduced by the same head are output for both CH1 and C112, the mounting of the two heads of the double azimuth head pair causes vertical image blur due to positional deviation (recording wavelength for one horizontal scanning period). In order to prevent this from occurring, even if you set the running speed of the magnetic tape arbitrarily, vertical shake,
It has the characteristic of being able to obtain good images without noise.

The above is in standard mode. An embodiment regarding the removal of bar noise during variable speed playback has been described. Next, an example of a head configuration that also makes it possible to remove thin bar noise that occurs during long-time playback will be described. FIG. 5 shows an example of such a head configuration. Here, FIG. 5 shows the head configuration itself as explained in the conventional example.

Next, the actual operation will be explained. First, in the case of standard mode, during variable speed playback, the head output on the CI (2 side) is switched and output in real time, and on the CHl side, the signal of one field played on the CI2 side is stored. The output is now "°C" again. Through this operation, it is possible to obtain continuity (no. An image with a good ratio can be obtained.Next is the long-time mode, but in the second case, switch the I\SoD output on the C11l side and output it in real time, and then on the CI2 side.

By outputting the one-field reproduction signal again on the CH1 side, it becomes possible to obtain a good variable speed reproduction image.

In other words, the recording track width in long-time mode is 19 μm.
If a wide head such as 58 μm is used, it will pick up signals from adjacent tracks that cannot be removed by the azimuth angle, resulting in image deterioration. The above problem is solved by using a head.

In other words, in emblem mode and long time mode, variable speed playback
By choosing the double azimuth head pair to be used, it is possible to obtain good images in both modes.

Although the present invention has been described above with reference to two embodiments, the present invention is of course not limited thereto. In other words, the present invention can be implemented as long as there are at least 111 pairs of double azimuth heads, so various head configurations can be considered.

[Effects of the Invention] According to the present invention, it is possible to improve high-speed reproduction images in the standard mode by simply using one pair of double azimuth heads, and furthermore, by using a pair of 2FFI double azimuth heads, it is possible to improve high-speed reproduction images in the long-time mode. It is also possible to improve the

Furthermore, it is effective because images without vertical blur can be obtained no matter what speed the magnetic tape is run at.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
FIG. 3 is a diagram showing an example of the head configuration in FIG. 1, FIG. 3 is a track pattern of a magnetic tape in the head configuration shown in FIG. 2, FIG. 11 is a diagram showing the operating principle of the present invention, and FIG. 5 is a conventional example. This figure is also an example of another head configuration included in the embodiment of the present invention. FIG. 6 is a track pattern of a magnetic tape in the head configuration of FIG. 5, and FIGS. 7 and 8 are diagrams showing the operating principle of the conventional example. 1.2.3...Magnetic head, 7...Head switching control circuit, 11...A/D converter, 12...Memory circuit. 14... D/A converter Akira 2 Ward man: 5 same place 4 Figure (LI CHI CH2 [6) ■ Easy 5I2] 1st bar ft CHl c/-/2 CHI CH2 Procedural amendment (method) % formula % 2 name Name of the person who corrects the magnetic recording and reproducing device + if relationship Patent applicant name Name '5lot Co., Ltd.
Hitachi Production Orisari Hitosho's Object Diagram

Claims (1)

[Claims] a rotating cylinder having at least one magnetic head pair consisting of two magnetic heads having different azimuth angles; A magnetic recording and reproducing device comprising means for selectively switching heads and a storage device for storing one field of signals, characterized in that information stored in the storage device is updated in a field in which the pair of magnetic heads traces a magnetic tape. magnetic recording and reproducing device.