CN1258063A - Method for non-volatile recording/replay of magnetic recording medium - Google Patents

Abstract

The invention relates to a method for prolonging nonvolatile recording/replay time of magnetic recording medium having limited recording capacity. Wherein three recording/replay methods are provided. The first method is by employing one of a pair of rotary magnetic heads which have different azimuth to intermittently choose input video signal and record the same on tape whose moving speed is slower than standard speed, and by complementing lose field signal to continuously replay the video signal.

Description

Non-volatile recording/the playback method of magnetic recording media

The present invention relates generally to by rotating magnetic head vision signal to be specifically related to a kind of record of magnetic recording media and method that playback duration prolongs made from limited recording capacity to magnetic recording media record or from the method for magnetic recording media playback of video signal.

The boxlike video function writes down vision signal how long in such as the magnetic recording media of video-tape merits attention very much.But, have fixing standard owing to hold the size of the tape cassete of tape reel, so the recording capacity of videocassette is limited.

Therefore, the translational speed of tape is reduced to standard speed (33.35mm/sec) thus half or 1/3rd can Duo 2 or 3 times signal record to tape than the standard recording pattern.In the case, track width be reduced to normal width half or 1/3rd, thereby recording density improved and obtain longer writing time.Following table shows according to the record of the T-120 tape of the VHS pattern of above-mentioned conventional method hour.

Project	The standard speed pattern	The extension play mode
			Writing time	2 hours	6 hours
The tape translational speed	????33.35mm/sec	????11.12mm/sec
			Track width	????58μm	????19.2μm

As above shown in the table, standard speed pattern (after this being called " SP pattern ") can write down 2 hours vision signal in the T-120 magnetic tape cassette.And be reduced in 1/3 the extension play mode (after this being called " EP pattern ") of SP pattern in the tape translational speed, can be with 6 hours vision signal of high density recording.

But, above-mentioned have a defective by reducing the method that the tape translational speed writes down more vision signals, promptly under the condition of same magnetic head width and identical magnetic head switch speed, if be set to the subcritical value for writing down more signal tape translational speed, then adjacent track may be overlapping.

Correspondingly, owing to when resetting the vision signal that writes down in the above described manner, can crosstalk, therefore can't obtain the desired images quality.

An object of the present invention is to provide a kind of recording/reproducing method, can obviously prolong the high-quality that also keep institute's recorded video signal writing time simultaneously.

To achieve these goals, the invention provides a kind of method, it utilizes a magnetic head in the mutually different rotating magnetic head in a pair of position angle, off and on incoming video signal is selected and record its translational speed to be slower than on the tape of standard speed, and it comes playback of video signal continuously by the signal that replenishes the disappearance field.

To achieve these goals, the present invention also provides another kind of method, a magnetic head in a pair of magnetic head on being installed in the head drum that its rotational speed is slower than the standard rotational speed is through magnetic recording media, just a plurality of videos field is recorded its translational speed and be slower than on the magnetic recording media of standard speed, thus the writing time of prolongation progressive video.

To achieve these goals, the present invention also provides another kind of method, its utilization is installed in its rotational speed and is exclusively used in a pair of magnetic head of non-volatile recording/playback faster than being designed on the head drum of standard rotational speed, single video field is recorded its translational speed respectively be slower than in a plurality of video tracks of magnetic recording media of standard speed.

The accompanying drawing that is comprised provides further understanding of the present invention with instructions, has wherein shown the preferred embodiments of the present invention, is used to explain principle of the present invention.

In the accompanying drawings:

Fig. 1 is the schematic block diagram of videocassette recorder;

Fig. 2 A and 2B are the block schemes of signal processor detailed structure in the displayed map 1;

Fig. 3 is the process flow diagram that shows according to the embodiment of the non-volatile recording method that is used for magnetic recording media of the present invention;

Fig. 4 is the process flow diagram that shows corresponding to the playback method of the recording method among Fig. 3;

Fig. 5 shows the track pattern by the record of the non-volatile recording method among Fig. 3;

Fig. 6 shows the track pattern of conventional extension play mode (EP pattern) record;

Fig. 7 shows the vertical flyback interval of the TV signal that is used for odd field and even field;

Fig. 8 A shows according to the non-volatile recording method among Fig. 3, the recording geometry and the waveform of several points in the playback portion of Fig. 2 B;

Fig. 8 B is presented at the track pattern that is write down under the situation about having changed the writing time in the method that Fig. 3 describes;

Fig. 9 is the process flow diagram that shows another embodiment of the non-volatile recording method that is used for magnetic recording media according to the present invention;

Figure 10 is the process flow diagram that shows corresponding to the playback method of the recording method of describing among Fig. 9;

Figure 11 is the detailed schematic block diagram of playback portion of signal processor of Fig. 1 that is used for the playback method of Figure 10;

Figure 12 A shows the track pattern by the non-volatile recording method record of describing among Fig. 9;

Figure 12 B is presented in the method that Fig. 9 describes the track pattern that is write down under the situation of different recording time is set;

Figure 13 is the process flow diagram of another embodiment that is used for the non-volatile recording method of magnetic recording media according to the present invention;

Figure 14 is the process flow diagram that shows the playback method corresponding with the recording method described among Figure 13;

Figure 15 is the schematic block diagram that shows the switch unit detailed structure of the Fig. 1 that realizes the recording method described in Figure 13 and 14 and playback method respectively;

Figure 16 is presented at the example that the position that magnetic head switches takes place in each of vision signal;

Figure 17 A shows the track pattern by the non-volatile recording method record of Figure 13;

Figure 17 B is presented in the method that Figure 13 describes the track pattern that is write down under the situation of different recording time is set.

Below with reference to the accompanying drawings the preferred embodiment that is used for the non-volatile recording/playback method of magnetic recording media according to the present invention is elaborated.

Fig. 1 shows a kind of block scheme of realizing the record/playback apparatus of the inventive method, and comparing with conventional videocassette recorder can be with video signal recording for more time to magnetic recording media.This device comprises: signal processor 30 is used for vision signal is carried out signal Processing with record or replay signal; Switch unit 20 is used for optionally I/O tracer signal or replay signal; VHS pattern magnetic head A and B, its width are 26 μ m, are used for extracting the signal that is write down at SP and EP pattern to tape 10 recorded video signals with from tape 10; Control head CTL; Pulse producer 40 is used to produce magnetic head switch pulse (H/S) and it is loaded on switch unit 20; Driven motor 70 is used to drive tape 10 and moves with constant speed; Servo unit 60 is used to drive driven motor 70 and head wheel motor (not shown); With microprocessor 50, be used to control servo unit 60, the operation of switch unit 20 and signal processor 30.

The recording portion of the signal processor 30 that shows among Fig. 2 A comprises: frequency modulator 31 is used for the composite video signal from the outside input is converted to frequency modulated signal; Balanced device 32 is used for the frequency characteristic of compensating frequency modulation signal; With amplifier 33, the signal that is used for being compensated is amplified to predetermined level.

The playback portion of the signal processor 30 that shows among Fig. 2 B comprises: prime amplifier 34, and the signal that is used for being reset by the magnetic head that uses at logging mode is amplified to predetermined level; Balanced device 35 is used to compensate by the frequency characteristic of preposition amplifying signal to improve its signal to noise ratio (SNR); Luminance signal (after this being called " Y-signal ") and carrier chrominance signal (after this being called " C signal ") detuner 36 and 37 is respectively applied for and will be demodulated into Y-signal and C signal by preposition amplifying signal; Frequency mixer 38 is used for demodulation gained Y-signal and C signal are mixed into composite video signal; A/D converter 44 is used for the composite video signal from frequency mixer 38 outputs is converted to numerical data; Field memory 39 is used for the numerical data that temporary transient storage is changed; Data converter 41 is used to change the field type of the video data of obtaining from field memory 39; D/A converter 42 is used for video data is converted to simulating signal; With signal selector 43, be used for alternately selecting two input signals to set up complete frame of video.

Be elaborated below with reference to Fig. 3 and 4 pairs of first preferred embodiments that are used for the non-volatile recording/playback method of magnetic recording media according to the present invention.

If the user keys in the request (S01) of XP mode record, in this logging mode the tape translational speed be set to standard speed 33.35mm/sec 1/6 so that prolong writing time, microprocessor 50 is controlled the rotational speed of driven motors 70 by servo unit 60, thereby makes the translational speed of the tape 10 that is driven by driven motor 70 become the 5.56mm/sec corresponding with the XP pattern.

If tape 10 begins to move forward and its speed has reached control rate, 30 pairs of input signals of microprocessor 50 enable signal processors are handled (S03), making signal processor 30 handle the composite video signal of importing from the outside and be converted into the signal (S04) that is suitable for being recorded on the tape 10, below is to describe in detail.

When composite video signal was input to frequency modulator 31 signal processor 30 from the outside, the Y-signal of 31 pairs of composite video signals of frequency modulator carried out different modulation with the C signal.That is, Y-signal is by frequency modulation (PFM) to 3.4～4.4MHz frequency range, and the C signal is down converted to the frequency range of 629kHz ± 500Hz.When the Y-signal of being modulated and C signal are loaded on balanced device 32, balanced device 32 plays incentive action to noise according to its characteristic default equalizer curve compensates the frequency characteristic of input signal, and amplifier 33 is amplified to particular level with the signal that is compensated.

Simultaneously, pulse producer 40 produces the magnetic head switch pulse of 30Hz and provides it to switch unit 20, but microprocessor 50 switch units 20 are controlled (S05), only select a magnetic head among magnetic head A and the B so that do not rely on the magnetic head switch pulse that is loaded.The magnetic head of being chosen (for example magnetic head A), the odd field (or even field) of the vision signal that tracer signal amplifier 33 is amplified is with first odd field (odd1) as shown in Figure 5, second odd field (odd2), the 3rd odd field (odd3) ... order carry out record.Therefore, this recording geometry and its tape speed are that the conventional EP pattern of SP pattern tape speed 1/3 is compared different.Figure 6 shows that the formed recording geometry of EP pattern, a pair of magnetic head A that alternately once selected in wherein per 1/60 second and B be according to first odd field (odd1), first even field (even1), second odd field (odd2) ... order come recorded video signal.

Next will illustrate in greater detail the process of carrying out the information record according to track pattern shown in Figure 5.In the process of selected magnetic head A sweep recording tape 10, a field of magnetic head A recorded video signal.On the other hand, at relative magnetic head B through in the process of recording tape 10, because magnetic head B do not link to each other with input signal, so next field of recorded video signal not.After the intact tape 10 of magnetic head A sweep, because tape speed is EP pattern medium velocity half, so the distance that tape moves will become institute's displacement in the EP pattern half.After this, will in the scanning process of magnetic head B, finish second half processing.Therefore, the distance that is moved will become " L " (as shown in Figure 5), and it equals, and rotary head cylinder revolves the distance that tape moved when turning around in the EP pattern.Therefore, by width be next magnetic track of being write down of the magnetic head A of 26 μ m will be not can with last magnetic track overlaid, and will only write down odd number (or even number) as shown in Figure 5.

In addition, field of the every record of control head CTL, just the control magnetic track write head switch pulse (S07) below the video track that is arranged in tape 10.

The width L of formed magnetic track is identical with this parameter value in the EP pattern shown in Figure 6 on the video track with the tape 10 of the low speed tape transport in the XP pattern, i.e. 19 μ m.Continuation is carried out non-volatile recording (close record) to the tape 10 with the constant low speed tape transport of 5.56mm/sec and is handled, and keys in the request (S09) that stops to write down up to the user.Finish if recording operation is performed until tape 10, the tape that then originally can write down two hours vision signals in the SP pattern can record length reach 12 hours vision signal.

When the user keys in the request that the vision signal of utilizing magnetic head A or B to be write down is reset in the XP pattern (S10), microprocessor 50 will be controlled servo unit 60 makes tape 10 with identical with writing speed, and size is the constant speed tape transport (S11) of 5.56mm/sec (SP pattern 1/6).

After this, control head CTL detects frequency from translational speed is the control magnetic track of tape 10 of 5.56mm/sec be the gating pulse (S12) of 30Hz, and it is loaded on the A/D converter 44 as conversion enable signal, microprocessor 50 is also controlled the magnetic head that 20 independent selections of switch unit were used to write down originally simultaneously, as the magnetic head A (S13) in the present embodiment.Finish after this handles, will reset out the selected magnetic head A field signal of (S14) of signal processor 30 is separated into Y-signal and C signal, and with following steps separating obtained signal is carried out demodulation process (S15).

Prime amplifier 34 is with the preposition predetermined level that is amplified to of signal of magnetic head A playback gained, and balanced device 35 then compensates the frequency characteristic of preposition amplification gained signal, to improve its SNR (signal to noise ratio (S/N ratio)).Subsequently, be loaded on Y-signal detuner 36 and the C demodulator of PM signal PM 37 through the vision signal after the over-compensation.Y-signal detuner 36 extracts Y-signal from input signal, and it is demodulated into normal Y-signal in 0～3MHz frequency range, C demodulator of PM signal PM 37 then extracts the C signal from input signal, and it is up-converted to the interior normal C signal of 3.58MHz ± 500KHz frequency range.Y-signal and C signal by 38 pairs of demodulation gained of frequency mixer carries out mixing subsequently, and it is exported to signal selector 43 (S16) as composite video signal.

In frequency is the A/D converter 44 that the high level of the switching signal of 30Hz is energized, and the composite video signal of output as mentioned above is converted to numerical data, subsequently with the data storage of an one field in field memory 39.Because store frequency after the data is that the switching signal of 30Hz will become low level with the de-energisation A/D converter, therefore for next field, before institute's video data stored will can not rewritten by noise.In the 30Hz switching signal keeps the low level time, microprocessor 50 will be searched out the video data of being kept in the field memory 39 and send it to data converter 41.Some data is deleted or inserted to data converter 41 so that the phase place of first equalizing pulse and the phase place of last equalizing pulse are become an another kind of type (S17) in vertical blanking interval.

For example, if the video data of being searched out belongs to odd field, then will delete or insert the data of 0.5H, thereby make odd field signal shown in Fig. 7 the first half (its first and last equalizing pulse respectively with adjacent separately interpulse 1H of being separated with and 0.5H), become the even field signal shown in Fig. 7 the latter half (its first and last equalizing pulse be separated with 0.5H and 1H respectively and separately between adjacent pulse).

It is converted to corresponding simulating signal through the video data that changes by D/A converter 42, microprocessor 50 is then controlled signal selector 43 according to the 30Hz switching signal, with output alternately directly from the odd field vision signal of frequency mixer 38 (among Fig. 8 A

With after storage, change even field vision signal that processing postponed (among Fig. 8 A by the field Therefore, be that generation is first odd field (oddl) in proper order from the result of signal selector 43 selectivity outputting video signals ( Fig. 8 A), first even field (evenl=odd1), the complete video (S18) of second odd field (odd2) or the like.

Continue executive chairman's time replay operations and (wherein alternately export the vision signal of being reset by magnetic head A or B, with the vision signal of resetting and handling through the interlude change afterwards), key in the request (S19) that stops playback up to the user, if and not from user's interrupt request, the tape that then is merely able to write down two hours vision signals in the SP pattern can playback reach 12 hours content.

In addition, the tape speed under the above illustrated XP pattern can be set to by the multiple result of standard speed divided by 6 multiple gained.This just means in the XP pattern can tape speed be set to 1/12,1/18 of SP pattern ... and 1/6.When the tape speed in the XP pattern shown in Fig. 8 B be set to the SP pattern 1/12 the time, per two magnetic head switching signal cycle microprocessors 50 will carry out the record of a vision signal and reset to handle by magnetic head A or B, so that record length is that two hours tape can record length be 24 hours a vision signal in the SP pattern.The record with replay operations in signal Processing identical with processing mentioned above.

Next with reference to Fig. 9 and process flow diagram shown in Figure 10 second preferred embodiment that is used for the non-volatile recording/playback method of magnetic recording media according to the present invention is elaborated.

Realize that the structure of the videograph/replay device of Fig. 9 and method shown in Figure 10 compares with the structure of device shown in Figure 1, except the head gap all identical slightly narrow than first embodiment.That is, the head gap of magnetic head A and B be designed to than the standard head gap of value between 0.3～0.35 μ m half is narrower, be magnetized to the high frequency characteristics of the signal in the tape with raising.If this gap is designed to the EP head gap half, then the relative frequency characteristic between rotating magnetic head and the tape can keep identical with the relative frequency characteristic in the recording/reproducing process under the EP pattern.

Different with Fig. 2 B, the playback portion of signal processor 30 shown in Figure 1 comprises prime amplifier 34 and balanced device 35, and Y-signal detuner 36 and C demodulator of PM signal PM 37, and frequency mixer 38 are to realize Fig. 9 and method shown in Figure 10.

Next with reference to said structure, to being used for second preferred embodiment that magnetic recording media prolongs writing time and being elaborated according to of the present invention shown in Fig. 9 and 10.

If customer requirements writes down to prolong writing time (S21) according to the XP pattern, then microprocessor 50 will be controlled by the rotational speed of 60 pairs of driven motors 70 of servo unit, so that tape 10 is the constant speed tape transport of 5.56mm/sec with the size corresponding to desired XP pattern.In addition, microprocessor 50 is also controlled servo unit 60 and is carried in driving voltage (the 180 ° of magnetic heads in a pair of space are installed on the head drum) on the head wheel motor that is used for the rotating head drum (not shown) with reduction, be reduced to half of standard speed 1800rpm, i.e. 900rpm with rotating speed with head drum.If the rotating speed of head drum is reduced to 900rpm, then for the relative velocity of tape also with drop by half, so the frequency characteristic in the recording process is with variation and not compensation.Therefore, compare, in the present embodiment head gap reduced half with the head gap of routine so that hold the record or the relative frequency characteristic of playback duration, that is, though head drum with the situation of the rotating speed rotation of 900rpm under high fdrequency component can not disappear yet.

Head drum is with the speed rotation of 900rpm if tape speed reaches 5.56mm/sec, then as described in the above-mentioned embodiment, microprocessor 50 will load a control signal and operate (S23) to enable signal processor 30, and the signal processor 30 after enabling will be handled (S24) to the composite video signal of importing from the outside, and be converted into the signal that is suitable for recording on the tape 10.

Meanwhile, microprocessor 50 clamp-pulse generators 40 are with the frequency halving with the magnetic head switching signal, wherein pulse producer 40 is the switching signal of 15Hz with the magnetic head switching signal of 30Hz frequency division again with the frequency that obtains being loaded on the switch unit 20.Therefore, switch unit 20 once comes to choose one by one magnetic head A and the B that is installed on the head drum by second upset of per 1/ (15 * 2).

Replace selected magnetic head A and B scanning tape 10 as mentioned above, per 1/30 second simultaneously just to magnetizing with the tracks corresponding to the tape 10 of the low speed tape transport of XP pattern.Therefore, at a magnetic head A or B scanning tape 10 in the tracks shown in Figure 12 A, with record from two fields of the vision signal that includes an odd field (odd1) and an even field (even1) of amplifier 33 outputs (S25, S26).And two fields of every record (odd field+even field), convenient is the magnetic head switching signal (S27) of 15Hz with control head CTL recording frequency on the control magnetic track below the video track that is positioned at tape 10.

In as the formed track pattern of Figure 12 A, because identical in the width of the magnetic head A that adopted and B and the EP pattern in the present embodiment, the width of magnetic track " B " almost equates with track width in the EP pattern, is 19 μ m.

The tape speed of present embodiment is half in the EP pattern, but owing to two video fields in this XP pattern are recorded on the tracks, so the sweep time of tape 10 is identical with the sweep time of conventional EP pattern.Therefore, because the displacement corresponding to the magnetic head width is equal to each other in every kind of pattern, so the width of the magnetic head in the present embodiment can be identical with the EP magnetic head.

When user in the XP pattern keys in the request that the vision signal that is write down by magnetic head A and B is reset (S30), microprocessor 50 will be controlled servo unit 60, so that the translational speed of tape 10 is identical with writing speed, be 5.56mm/sec (SP pattern 1/6), also the rotating speed of head drum be controlled to be half (S31) of normal speed simultaneously.

After this, detect the gating pulse (S32) that the frequency that is write down is 15Hz in the control magnetic track of control head CTL with the tape 10 of controlled velocity tape transport, and microprocessor 50 receives detected gating pulse, and switch unit 20 is controlled alternately to choose magnetic head A and B (S33) according to impulse level.In the case, when certain the specific magnetic head (as magnetic head A) and the level transitions of 15Hz gating pulse are synchronous and selected, signal processor 30 is separated into Y-signal and C signal with two fields (odd number and an even field) of the vision signal of magnetic head A playback (S34) gained, carry out as the described a series of demodulation process of first embodiment (S35), by frequency mixer 38 Y-signal of demodulation gained is in the same place with the C signal mixing, and its composite video signal as two fields exported (S36, S37).

Continue to carry out the long-time replay operations that wherein video-tape is scanned at every turn two fields (coupling and an even field) of playback of video signal respectively by magnetic head A (or B), stop to carry out playback up to customer requirements, if and not from user's interrupt request, the playback length that then is used to write down the tape of two hours contents in the SP pattern was 12 hours.

In addition, the rotational speed of head drum can be set to the standard speed of the 1800rpm multiple velocity amplitude divided by 2 multiple gained in the XP pattern.For example, if the rotating speed of head drum is set to 450rpm (rated speed 1/4), and the translational speed of tape is reduced to 2.78mm/sec (EP pattern 1/4) simultaneously, then microprocessor 50 is by being that the magnetic head switching signal of 7.5Hz replaces the magnetic head of being chosen according to institute's loading frequency, can go out four fields of the vision signal of its figure shown in Figure 12 B at recording/reproducing in the wall scroll magnetic track, thereby utilizing present embodiment, the tape that can write down 6 hours vision signals in the EP pattern can write down and reach 24 hours content.

Next with reference to Figure 13 and process flow diagram shown in Figure 14 the 3rd preferred embodiment that is used for the non-volatile recording/playback method of magnetic recording media according to the present invention is elaborated.

The structure that is used to realize the videograph/replay device of Figure 13 and method shown in Figure 14 is compared with structure shown in Figure 1, except the former adopted be exclusively used in the XP magnetic head that non-volatile recording/playback handles all identical.The width of these XP magnetic heads is different with the width of the magnetic head that is used for SP or EP pattern.Wherein reduced the width of XP magnetic head, so that be 1/3 of EP pattern track width by the track width that this magnetic head write down, i.e. 6.5 μ m.The width that reduces magnetic head for the width of constriction magnetic track can prevent to produce between the adjacent track and disturb.

Different with Fig. 2 B, the playback portion of signal processor 30 shown in Figure 1 comprises prime amplifier 34, balanced device 35, and Y-signal detuner 36 and C demodulator of PM signal PM 37, and frequency mixer 38 are to realize Figure 13 and method shown in Figure 14.Switch unit 20 shown in Figure 15 comprises: horizontal sync detector 21 is used to detect the horizontal-drive signal from incoming video signal; Frequency multiplier 23, being used for will be from the doubling frequency of the 30Hz magnetic head switching signal of pulse producer 40 input; And magnetic head switch controller 22, be used for by to counting the horizontal synchronization that detects on the precalculated position by horizontal sync detector 21 detected horizontal-drive signals, and will from frequency multiplier 23 through the marginal position of the 60Hz magnetic head switching signal of process of frequency multiplication gained adjust to predeterminated level synchronously within.

Next with reference to said structure,, be used for the preferred embodiment that magnetic recording media prolongs the magnetic recording time and be elaborated shown in Figure 13 and 14.

If user command writes down to prolong writing time (S41) with the XP pattern, then microprocessor 50 will be by the rotational speed of servo unit 60 control driven motors 70, so that tape 10 is with corresponding to required XP pattern, size is the constant speed tape transport of 5.56mm/sec, and the control head drum motor is the twice of standard speed 1800rpm, i.e. 3600rpm so that the rotating speed of head drum increases in addition.

Even under the situation identical of the gap of XP magnetic head with the gap of EP magnetic head, because the rotating speed of head drum is doubled to make that the relative frequency characteristic is improved in recording process, so it still can guarantee higher record quality.

If tape 10 is according to above-mentioned controlled velocity tape transport, then microprocessor 50 is operated enable signal processor 30, is converted to tracer signal with the composite video signal that will be imported, and exports after compensation.

Meanwhile, if microprocessor 50 has loaded the control signal that is used for the non-volatile recording pattern to switch unit 20, then switch unit 20 will be the doubling frequency from the 30Hz magnetic head switching signal of pulse producer 40 input, and alternately selects special-purpose magnetic head XPA and XPB for use according to the level of the 60Hz magnetic head switching signal of frequency multiplication gained.

That is, the frequency that will be produced from pulse producer 40 is that the magnetic head switching signal of 30Hz is loaded on the frequency multiplier 23, is 60Hz by frequency multiplier 23 with the doubling frequency of magnetic head switching signal.

Tracer signal from signal processor 30 is sent to horizontal sync detector 21, so horizontal sync detector 21 is after the 22nd horizontal-drive signal of the beginning of detected representative shown in the first half of Figure 16 end of vertical blanking interval (VBI) and first odd field (odd1), just begin horizontal-drive signal is counted.When count value becomes 119, horizontal sync detector 21 will detect the interval time that the 143rd horizontal synchronization continues.In addition, horizontal sync detector 21 is also carried out similar operations to detect the specific interval corresponding to the horizontal-drive signal of the even field shown in Figure 16 the latter half.The specific interval that will detect for even field be the 406th synchronously.

When detecting so specific interval, and during horizontal sync detector 21 output corresponding intervals pulses, magnetic head switch controller 22 will be adjusted the phase place of 60Hz magnetic head switching signal, so that be positioned within this spacing pulse from the level transition points of the 60Hz magnetic head switching signal of frequency multiplier 23 input.Therefore, switch a magnetic head in the field and just can construct a full screen image, thereby can prevent that vision signal is damaged.Utilize frequency to be used for the magnetic head XPA and the XPB of this kind non-volatile recording for the phase controlled magnetic head switching signal alternate selection of 60Hz, per 1/120 second (half of the time of single video field) carries out record to a tracks on the tape corresponding to the low speed tape transport of XP pattern.

Therefore, arbitrary, for example 1/60 second the odd field (odd1) that is amplified and exported by amplifier 33 is divided on two tracks, thereby by a pair of XP pattern magnetic head XPA and the XPB record of alternately choosing one as mentioned above in per 1/120 second.And per 1/60 second control magnetic track below the video track that is arranged in tape 10 of control head CTL is noted the magnetic head switching signal.

Shown in Figure 17 A, formed track width is 4.75 μ m on the video track of the tape 10 that carries out tape transport with the low speed corresponding to the XP pattern, only compare with the magnetic track (as shown in Figure 6) in the EP pattern for its 1/4.

If the user keys in the request (S50) that the vision signal that is write down is as mentioned above reset, then microprocessor 50 will be controlled servo unit 60 and make tape 10 with identical with the XP pattern, and size is carried out tape transport (S51) for the writing speed of 5.56mm/sec (half of EP pattern).

After this, control head CTL detects the gating pulse (S52) that the frequency that is write down is 60Hz from the control magnetic track with the tape 10 of controlled velocity tape transport, microprocessor 50 then receives detected gating pulse, and control switch unit 20 is alternately to select magnetic head XPA and XPB (S53) for use according to the level of 60Hz control signal.Also will carry out the phase place adjustment in addition, and to be located within the predeterminated level sync interval of playback of video signal, thereby make it in playback procedure, can not produce switching noise (switchingnoise) the tr pt of magnetic head switching signal.Under this playback situation, if with frequency be that the control signal of 60Hz has been chosen magnetic head XPA and XPB synchronously, then signal processor 30 will be by magnetic head XPA and twice scanning of XPB (S54) and an independent video field (first and second moieties (half) of odd field) of playback gained is separated into Y-signal and C signal, carry out subsequently as the described a series of demodulation process of first embodiment (S55), by frequency mixer 38 Y-signal and the C signal of demodulation gained carried out mixing, and with its as complete of of composite video signal export (S56, S57).

In addition, the rotating speed of head drum can be set to the multiple velocity amplitude that standard speed with 1800rpm multiply by 2 multiple gained in the XP pattern.This means can head drum rotating speed be set to 7200rpm (normal speed four times) and 3600rpm.And tape speed is reduced to 2.78mm/sec (EP pattern 1/4), simultaneously the magnetic head width is designed to 1/8 of normal width, to realize reducing of head drum rotating speed.Figure 17 B is depicted as recording geometry under these conditions.

In the case, microprocessor 50 by the magnetic head XPA that alternately chosen according to 120Hz magnetic head switching signal and XPB can be in 4 tracks record/or odd number of therefrom resetting (or an even number), thereby utilize present embodiment, record length is that 2 hours tape can write down 12 hours vision signal in the SP pattern, and still can keep good image quality simultaneously.

Although above disclose multiple preferred embodiment of the present invention for illustrative purposes, but those skilled in the art's be understood that can be carried out various ways ground to the present invention and be revised additional and replacement under the situation that does not deviate from claim spirit and scope of the present invention.

Claims (17)

1. a method that is used for the playback of video signal comprises the steps:

(a) to equal the constant speed movable recording media of writing speed;

(b) from recording medium, detect the signal that is write down;

(c) with detected signal Processing for being the composite video signal of unit with the video field;

(d) composite video signal of temporary transient stores processor gained;

(e) alternately export the composite video signal of processing gained in the described step (c) and the vision signal of being kept in.

2. the method for claim 1, wherein said step (e) is adjusted the vision signal of being kept in, and the vision signal to utilize direct output without storage makes up a complete frame of video, alternately it is exported subsequently.

3. method as claimed in claim 2, wherein said step (e) is adjusted the equalizing pulse between the video field signal.

4. one kind by being installed in the method for a pair of head records vision signal on the rotary head cylinder, comprises the steps:

(a) to be lower than the writing speed movable recording media of EP mode speed;

(b) incoming video signal being treated to the video field is the tracer signal of unit; And

When (c) magnetic head scans recording medium therein, once note a plurality of treated videos field.

5. method as claimed in claim 4, wherein can from the EP mode speed divided by selecting translational speed 2 the multiple gained result, and the number of described a plurality of video field signals is 2 multiple.

6. method as claimed in claim 5, wherein can from rated speed divided by the rotating speed of selecting rotary head cylinder the result of 2 multiple gained.

7. method as claimed in claim 4, the head gap of wherein said a plurality of magnetic heads is taken as half of EP head gap, to remain on available relative frequency characteristic in the EP pattern between magnetic head and recording medium.

8. one kind by the reset method of the vision signal that write down of a pair of rotating magnetic head, comprises the steps:

(a) to equal the speed movable recording media of writing speed;

(b) when one of them the head scanning recording medium that rotates with the speed that is lower than normal speed once, detect a plurality of video fields of being write down;

(c) detected a plurality of videos field is separated into independent video field, and separating obtained video field is treated to composite video signal.

9. method as claimed in claim 8, the head gap of wherein said a plurality of magnetic heads is taken as 1/2 of EP head gap, to keep available relative frequency characteristic in the EP pattern between magnetic head and recording medium.

10. a method of coming recorded video signal by a pair of rotating magnetic head comprises the steps:

(a) to be lower than the speed movable recording media of EP mode record speed;

(b) vision signal of being imported being treated to the video field is the tracer signal of unit; And

(c) tracer signal that will handle a field of gained records in two of recording medium or the plurality of tracks, wherein respectively every tracks is carried out record by the magnetic head of choosing successively.

11. method as claimed in claim 10, the gap of wherein said magnetic head equals the gap of EP pattern magnetic head.

12. method as claimed in claim 10, wherein the width of magnetic head is 6.5 μ m less than the width of EP pattern magnetic head thereby make the width of recording track on the recording medium.

13. method as claimed in claim 10, wherein can from the EP mode speed divided by selecting translational speed 2 the multiple gained result.

14. method as claimed in claim 10, wherein said step (c) is divided into the signal subsection that number is 2 multiple with a field of vision signal, and each signal subsection is recorded in respectively in the independent tracks.

15. method as claimed in claim 14, wherein said step (c) is the magnetic head of 2 multiple of normal rotational speed by a pair of its speed, divides and a field of recorded video signal.

16. one kind by the reset method of the vision signal that write down of a pair of rotating magnetic head, comprises the steps:

(a) to equal the speed movable recording media of writing speed;

(b) come the signal of detection record in many recording tracks by a pair of magnetic head of being chosen successively;

(c) detected signal is configured to the independent field of vision signal; And

(d) the video field that will make up gained is treated to composite video signal.

17. method as claimed in claim 16 is wherein switched selection between this is to magnetic head within the horizontal synchronization of institute's detection signal.

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