JPS6318884A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable the special reproducing of a good quality in a device with a pair of magnetic heads azimuthes which are different from each other by executing the slow motion reproducing of the fraction of one by odd number through the use of a picture memory circuit. CONSTITUTION:A slow motion ratio set circuit 22 which enables a selection limiting a slow motion ratio to the fraction of one by odd number, a picture memory circuit 23 which renews and stores the reproduced output of either a head 2a or 2b scanning the maximum reproducing area against a recording track at the time of the slow motion reproducing, a change-over switch 7 which outputs said reproduced picture until the next time of renewing and storing and instead of the reproduced output of the pair of heads, and mode selection circuit 25 which switches the renewed storage of the picture memory circuit 23 into a main mode to equally renew and store the reproduced output of both heads or into a sub-mode to select, renew and store only the reproduced output of one head, are provided. At the same time that the slow motion ratio is limited to the fraction of one by odd number, the picture memory circuit renews and stores the reproduced output at the case that the magnetic head scans the maximum reproducing area at the time of the slow motion reproducing, and outputs the reproduced picture stored in the picture memory circuit, for a time until a next renewing and a storing are executed, and instead of the reproduced output of the magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a magnetic recording and reproducing apparatus that enables high-quality special reproduction by slow motion reproduction using an image memory circuit.

[Prior Art] A household magnetic recording and reproducing device used for recording and reproducing video signals uses a helical scan system in which a pair of magnetic heads with different azimuths scans diagonally across a magnetic tape while recording or reproducing video signals. This is the basic method, but in order to suppress noise generation during special playback such as still image playback and slow motion playback, in addition to a pair of magnetic heads for normal playback, a magnetic head with the same azimuth as one magnetic head is generally used. Many devices have a configuration in which a magnetic head is placed near the other magnetic head, and an image reproduced by one magnetic head and the magnetic head for special reproduction is output during special reproduction. However, this type of conventional magnetic recording and reproducing device requires a magnetic head for special reproduction in addition to the magnetic head for normal reproduction, which inevitably increases the cost. However, it is not possible to completely banish the noise bar that is associated with special playback from the screen.
As the number of magnetic heads increases, the wear of the magnetic tape also increases, which tends to impair durability.

Therefore, by using an image memory circuit that can store video signals for one field, and by using the playback output with the maximum playback envelope obtained from the magnetic head, still image playback can be performed using special playback such as slow motion playback. By doing so, a magnetic recording and reproducing device was proposed that enabled high-quality special reproduction. FIG. 4 shows only the signal reproducing system of the conventional magnetic recording/reproducing apparatus 1 according to this proposal. The magnetic recording/reproducing device 1 shown in the figure also includes a pair of rotating magnetic heads 2 disposed at positions dividing the circumference of a head drum 2 into two.
The video signals a and 2b read out alternately from the magnetic tape 3 are FM-demodulated for the luminance signal in the video reproducing circuit 4, and the color signals are frequency-converted and then mixed together, which is the same as the conventional method. However, in the video reproduction circuit 4, a signal line 5 and an image memory circuit 6 capable of storing video signals for one field are connected in parallel, and the signal line 5 or the image memory circuit selected by the changeover switch 7 is connected in parallel. 6 is connected to the reproduction output terminal 8.

During slow motion playback, the magnetic head 2a
Alternatively, the reproduced output of 2b is updated and stored in the image memory circuit 6 as appropriate, and the reproduced image stored in the image memory circuit 6 is
Until the next update storage is performed, noise is removed by outputting the output instead of the reproduction output of the pair of magnetic heads 2a and 2b.

During the slow motion playback period, the image memory circuit 6 and the changeover switch 7 are controlled by the write control signal and the changeover control signal from the control circuit 9. 4. I/6. , , etc. A slow motion ratio setting circuit 1 having a plurality of selection keys 10a for setting a slow motion ratio of 1/1 of the number of
0, a frequency division circuit 13 that divides the head switching pulse output from the head switching pulse generation circuit 11 that switches between the pair of magnetic heads 2a and 2b according to the slow motion ratio, and A control head 12 for reading control signals is connected thereto.

Now, for example, set 1/2 to the slow motion ratio setting circuit IO.
Assume that when the slow motion ratio is set, the maximum reproduction area is obtained when one of the magnetic heads 2a scans the recording track of the magnetic tape 3 shown in a matte pattern, as shown in FIG. In this case, the maximum reproduction area by the magnetic head 2a will be obtained again in the fifth tracing thereafter. Therefore, the control circuit 9 stores the reproduction output of the magnetic head 2a when the maximum reproduction envelope is obtained, and continues until the next maximum reproduction envelope is obtained.
The changeover switch 7 is switched to the image memory circuit 6 side, and the reproduced image stored in the image memory circuit 6 is output instead of the output of the video reproduction circuit 4.

[Problems to be Solved by the Invention] In the conventional magnetic recording and reproducing device l according to the above proposal, the slow motion ratio during slow motion reproduction is set to one-th of the number of magnetic recording and reproducing devices, so as shown in FIG. Firstly, this is due to the difference in azimuth between the magnetic heads 2a and 2b, and when n is an integer, the reproduction envelope is maximum at the (4n-3)th trace, but at the (4n-1)th trace in the middle. This means that tracing will not produce any playback output at all.

Therefore, the control circuit 9 has no choice but to form a write control signal using a signal obtained by dividing the head switching pulse into 1/2 by the frequency dividing circuit 13, and the control circuit 9 has no choice but to form a write control signal using a signal obtained by dividing the head switching pulse by 1/2 in the frequency dividing circuit 13. .

For example, the reproduction output of one of the magnetic heads 2b is continuously reproduced, but the reproduction output of the other magnetic head 2b is not reproduced, and the video information recorded on the magnetic tape 3 is also reproduced in an even field. Otherwise, the reproduction will be biased toward one side of the odd-numbered field. Therefore, the slow-motion reproduced images of the conventional magnetic recording and reproducing apparatus I lack smoothness of movement and give a somewhat awkward impression.

[Means for Solving the Problems] The present invention solves the above-mentioned problems, and allows a pair of magnetic heads with different azimuths to alternately perform diagonal scanning to record signals on a magnetic tape. A magnetic recording and reproducing device that performs slow motion playback by running a tape at a tape speed multiplied by a slow motion ratio, the slow motion ratio setting being selectable by limiting the slow motion ratio to an odd fraction. an image memory circuit that updates and stores the playback output of a magnetic head that scans a maximum playback area with respect to a recording track during slow motion playback, and a playback image stored in this image memory circuit that is then updated and stored. In the meantime, a changeover switch outputs instead of the playback output of the pair of magnetic heads, and the update memory of the image memory circuit is set to a main mode that updates and stores the playback output of both magnetic heads equally, and one of the magnetic heads. The present invention is characterized in that it is configured by providing a mode selection circuit for switching between two sub-modes in which only the reproduced output is selected and updated and stored.

[Function] This invention limits the slow-motion ratio to one odd number, and updates and stores the reproduction output in the image memory circuit when the magnetic head scans the maximum reproduction area with respect to the recording track during slow-motion reproduction. By outputting the reproduced image stored in this image memory circuit in place of the reproduced output of the pair of magnetic heads until the next updated memory is performed, the image memory circuit can produce a system with no noise at all and high information density. By making slow-motion playback possible and changing the update storage mode of the image memory circuit as needed, the range of compatibility with magnetic tapes recorded by other magnetic recording and playback devices is expanded.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic circuit diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention, and FIGS. 2 and 3 show various parts of the circuit shown in FIG. 1 when magnetic heads with different head widths are used. FIG.

In FIG. 1, a magnetic recording/reproducing device 21 is provided with a slow-motion ratio setting circuit 22 that allows selection of the slow-motion ratio by limiting it to an odd fraction, thereby enabling slow-motion reproduction with high video information density. In order to change the update storage mode of the image memory circuit 23 as necessary and expand the range of compatibility with the magnetic tape 3 recorded by other magnetic recording and reproducing devices, a mode selection circuit 25 is provided in the control circuit 24.
is connected. Slow motion ratio setting circuit 2
2 is a circuit for setting the tape speed to be played back in slow motion at what fraction of the tape speed at the time of recording of the magnetic tape 3, and the slow motion is the tape speed ratio at the time of recording. The ratio is 1/3.115.1/
The selection is limited to odd numbers such as 7. The mode selection circuit 25 selects and stores the update memory of the image memory circuit 23 between a main mode in which the playback outputs of both magnetic heads 2a and 2b are updated equally, and a main mode that updates and stores only the playback output of one magnetic head 2a. The control circuit 24 is a circuit for switching between two sub-modes.
The control operation of is also changed.

The image memory circuit 23 has a storage capacity capable of storing the output of the video reproduction circuit 4 for one field.
When a high-level write enable signal is applied to the write control terminal, the memory contents are rewritten and the memory is updated during the application period. When the main mode is selected, the control circuit 24 outputs the divided output of the head switching pulse from the frequency dividing circuit 13 and the control head! When the control pulses from 2 have a certain phase relationship, a write permission signal is supplied to the write control terminal of the image memory circuit 6, and a switching control signal for switching the changeover switch 7 to the video reproduction circuit 4 side is supplied. . When the sub mode is selected, the image memory circuit 6 is activated only when the head switching pulse from the frequency dividing circuit 13 and the control pulse of one polarity from the control head 12 have a certain phase relationship. A write permission signal is supplied to the write control terminal, and a switching control signal for switching the changeover switch 7 to the video reproduction circuit 4 side is supplied.

Here, regarding the operation when a magnetic tape recorded with a magnetic head whose head width is 1/2 of the track pitch on the format is played back at a slow motion ratio of 1/3,
This will be explained with reference to FIG. In this case, long-term mode (LP
For magnetic tapes recorded in mode or β■ mode),
A guard band having the same width as the recording tracks is formed between adjacent recording tracks. Therefore, in 1/3 slow motion playback where the fourth trace reaches the point where the playback area is maximized for the adjacent track,
After one magnetic head 2a reproduces an odd field, the other magnetic head 2a undergoes incomplete reproduction in which only a part of the recording track is reproduced and reproduction failure due to the difference in azimuth.
b will reproduce the even field.

In this case, when the main mode is selected, the changeover switch 7 is switched to the image memory circuit 23 side during the period of incomplete reproduction and failure, so that when the maximum reproduction envelope is obtained, the magnetic head 2a, 2b is output instead of the output of the video reproduction circuit 4. Therefore, all recording tracks on the magnetic tape 3 are covered by the magnetic heads 2a and 2.
b can be played back alternately, thereby increasing the density of the video information forming the slow-motion playback image, and making it possible to obtain a high-quality playback image with smooth motion and no jittery feeling.

Furthermore, when the sub-mode is selected, the changeover switch 7 is switched to the image memory circuit 23 side not only during periods of incomplete reproduction and failure of reproduction but also during complete reproduction by the magnetic head 2b, so that the maximum reproduction envelope can be obtained. Only the reproduction output of the magnetic head 2a when the video signal is input is output instead of the output of the video reproduction circuit 4. This sub-mode is recorded by other magnetic recording/reproducing devices in which the head widths of the pair of magnetic heads are intentionally made different, or where differences in the indexing process that determines the placement of the pair of magnetic heads cause placement errors. This was provided for the purpose of expanding the range of compatibility when performing slow-motion reproduction of magnetic tape, which has slightly different recording tracks than self-recording. Therefore, only one of the even or odd fields of the recording track on the magnetic tape 3 is reproduced, but it is possible to perform slow-motion reproduction with suppressed noise, even though the magnetic tape produces some noise in the main mode.

Further, the operation when a magnetic tape recorded by a magnetic head whose head width is the same as the track pitch in the format is reproduced at a slow motion ratio of 1/3 is as shown in FIG. As is well known, both magnetic tapes recorded in long-time mode (LP mode or β■ mode) and magnetic tapes recorded in triple mode (EP mode or β old mode) have gaps between adjacent recording tracks. Some guard bands do not exist. However, in this case as well, since the fourth trace reaches the scanning where the reproduction area is maximized for exactly the adjacent track, in the main mode, the magnetic heads 2a and 2b have an error that reproduces only a part of the recording track. Odd and even fields are regenerated with complete regeneration and regeneration failure due to the difference in azimuth in between. In addition, in the sub-mode, only the reproduction output of the magnetic head 2a when the maximum reproduction envelope is obtained is output instead of the output of the video reproduction circuit 4, so that the recording tracks on the magnetic tape 3 are even-numbered or Only one of the odd fields will be played back, but even magnetic tapes that produce some noise in the main mode can be played back in slow motion with reduced noise.

In this way, the magnetic recording/reproducing device 1■ limits the slow-motion ratio to an odd-numbered fraction, and stores the reproduction output when the magnetic head 2a or 2b scans the maximum reproduction area in the image memory during slow-motion reproduction. The circuit 23 updates and stores the reproduced image stored in the image memory circuit 23, and the magnetic head 2a until the next updated storage is performed.
, 2b output in place of the playback output, it is possible to completely eliminate noise bars caused by track crossing during slow-motion playback, which is often seen in conventional two-head machines. By limiting it to 1/2, when selecting the main mode,
The pair of magnetic heads 2a output the reproduction output that maximizes the reproduction envelope obtained from the recording track on the magnetic tape 3.
, 2b evenly and at equal intervals, thereby making it possible to reproduce all the video information recorded on the magnetic tape 3 completely and evenly dividing the even and odd fields. It is possible to provide smooth slow-motion playback images with high video information density.

In addition, when playing back in slow motion a magnetic tape whose recording tracks are slightly different from self-recording, such as magnetic tape recorded by other magnetic recording/playback devices, by selecting the sub-mode, Only the even or odd fields of the recording track on the magnetic tape 3 will be played back, but even magnetic tape that produces some noise in the main mode can be played back in good slow motion with suppressed noise. Become.

[Effects of the Invention] As explained above, the present invention limits the sumi-motion ratio to an odd-numbered fraction and stores the playback output when the magnetic head scans the maximum playback area during slow-motion playback in the image memory. The circuit updates and stores the reproduced image stored in the image memory circuit, and outputs the reproduced image stored in the image memory circuit instead of the magnetic head reproduction output until the next updated memory is performed, which is similar to conventional two-head machines. It is possible to completely eliminate noise bars caused by track crossing during slow-motion playback, and in particular, by limiting the slow-motion ratio to one odd number, the main function is to update and store the playback output of both magnetic heads equally. When the mode is selected, the reproduction output that maximizes the reproduction envelope obtained from the recording track on the magnetic tape can be obtained evenly and at equal intervals from the pair of magnetic heads. All video information
It is possible to reproduce even and odd fields completely and evenly, and to provide smooth slow-motion reproduction images with high video information density. When performing slow-motion playback of a magnetic tape whose recording tracks are slightly different from those of self-recording, such as a magnetic tape with self-recording, a sub-mode in which only the playback output of one magnetic head is selected and updated is stored. By selecting this, only the even or odd fields of the recording track on the magnetic tape will be played back, but even magnetic tape that produces some noise in the main mode can be played back in good slow motion with suppressed noise. It has excellent effects such as making it possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention, and FIGS. 2 and 3 show various parts of the circuit shown in FIG. 1 when magnetic heads with different head widths are used. FIG. 4.5 is a schematic circuit configuration diagram and a signal waveform diagram of each part of the circuit, respectively, showing an example of a conventional magnetic recording/reproducing device. 2a, 2b,..., magnetic head, 311. magnetic tape, 7
．． ,, changeover switch, 21. ,,magnetic recording/reproducing device, 22. ,, slow motion ratio setting circuit, 23. ,,
Image memory circuit, 24. ,. control circuit, 25. ,,mode selection circuit.

Claims (1)

[Claims] Magnetic recording and playback that performs slow-motion playback by running a magnetic tape on which signals are recorded by alternately obliquely scanning a pair of magnetic heads with different azimuths at a tape speed that is the tape speed at the time of recording multiplied by a slow-motion ratio. The device includes a slow-motion ratio setting circuit that makes it possible to select the slow-motion ratio by limiting it to an odd fraction, and a reproduction output of a magnetic head that scans a maximum reproduction area with respect to a recording track during slow-motion reproduction. an image memory circuit for updating and storing the image; a changeover switch for outputting the reproduced image stored in the image memory circuit in place of the reproduction output of the pair of magnetic heads until the next time the image is stored; A mode selection circuit that switches the update storage of the memory circuit between two modes: a main mode in which the playback outputs of both magnetic heads are updated and stored equally, and a submode in which only the playback output of one magnetic head is selected and updated and stored. A magnetic recording/reproducing device comprising: