JPS5942617A - Magnetic recording and reproducing system - Google Patents

Abstract

PURPOSE:To record/reproduce easily two kinds of binary information or single ternary information in and from a single recording track, by making a differential pulse reproduced from a magnetic head correspond to information which is different in polarity. CONSTITUTION:When recording is executed by a saw tooth current which becomes a waveform (a) ''skip edge'' of a skip edge whose rise and fall are gentle and steep, respectively, reproducing voltage of a waveform (b) in which a pulse of negative polarity is formed in accordance with the skip edge in the fall direction is outputted from a magnetic head. On the other hand, when recording is executed by a saw tooth current whose rise shows a waveform a' having a steep skip edge and whose fall is gentle, a reproducing voltage waveform b' in which a pulse of positive polarity is formed in accordance with a skip edge in the rise direction is obtained. Therefore, when these waveforms (a), a' are combined suitably, or the like, and recording is executed by a recording current of a waveform which makes a direction of the skip edge of the waveform correspond to different kinds of information, respectively, it is outputted as a differential pulse of positive polarity and negative polarity, respectively, at the time of reproducing, therefore, two kinds of information can be discriminated and separated easily by the polarity of these differential pulses.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a recording/reproducing method for magnetically recording/reproducing digital information, and particularly relates to a recording/reproducing method for magnetically recording/reproducing digital information, and in particular to recording/reproducing information on a magnetic recording medium through a magnetic head that moves relative to the same medium. The present invention also relates to a magnetic recording and reproducing method for reproducing data from the same medium.

[Technical background of the invention]

Conventionally, when recording digital information on a magnetic tape via a magnetic head and reproducing it from the tape, a rectangular wave recording current as shown in FIG. In this case, the reproducing voltage obtained from the magnetic head during reproduction is a waveform obtained by differentiating the recording current waveform, as shown in Figure tb), and the rising and falling edges of the recording current are respectively Correspondingly, pulses of positive and negative polarity are generated. In order to reproduce the recorded information using the force 3, it is necessary to reproduce the recorded waveform using the above-mentioned differential curve of positive and negative polarity.

Therefore, in the above method, a single binary information is used.
It was not possible to record/reproduce the two types of 2 (straight 4 green reports) on a single recording track.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording/reproducing method that can easily record/reproduce two types of binary information or a single ternary information on a single recording track.

[Summary of the invention]

The present invention makes differential pulses reproduced by a magnetic head correspond to different information depending on the polarity, and uses a time-series combination wave of a sawtooth wave and a rectangular wave or a sawtooth wave as a recording signal, and the recording signal wave The jump edges in different directions are recorded so that they correspond to different digital value information, and during reproduction, the magnetic head obtains a differential output of the recorded signal and extracts the jump edges in different directions as pulses with different polarities. The present invention is characterized in that the above-mentioned digital value information is discriminately detected based on the above-mentioned information.

[Embodiments of the invention]

First, Figure 2 (at, (bl) and Figure 3 (at,
(A detailed description of the present invention will be given with reference to bl.

As shown in Figure 2 (&), the sawtooth wave current has a jump edge with a gradual rise and a steep fall (such a steep rise or fall edge is called a "jump edge"). When recording is performed, the magnetic head outputs a reproducing voltage having a waveform in which pulses of negative polarity are formed corresponding to the jump edges in the falling direction, as shown in FIG. 2(b). At this time, the gradual rising edge of the recording waveform causes a slight deviation in the reproduced waveform from the baseline depending on the magnitude of its slope, but this is a sufficiently small value compared to the differential pulse caused by the jumping edge.

In addition, when recording is performed with a sawtooth wave current that has a steep rise as shown in Figure 3 (at) and a sawtooth wave current that has a circular edge and a gentle fall, the jump in the rise direction as shown in Figure 3 (BL). A reproduced voltage waveform is obtained in which pulses of positive polarity are formed corresponding to the edges.

Therefore, by appropriately combining the waveforms in Figures 2 (,) and 3 (al), it is possible to record the waveform distribution current with the direction of the jump edge of the waveform corresponding to different types of information. During reproduction, one information is output as a positive differential pulse and the other information is output as a negative differential pulse, so the two types of information can be easily distinguished and separated based on the polarity of these differential pulses.

The first embodiment of the present invention based on such a principle is, so to speak, a theoretical embodiment, and FIGS. 4 (al to (r)) show its operating waveforms, and FIG. 5 shows the realization of the same embodiment. The main parts of the configuration for each are shown below.

Figure 4 (as shown in al., the digital values 11° and 101
The first input signal consists of binary digital information, and as shown in FIG. An example will be explained in which a second input signal consisting of binary digital information of IO and A recording current waveform is created by associating jump edges so that the information of the second input signal can be obtained as a negative pulse voltage as a pulse voltage.The recording current waveform is thus shown in the figure [el].

The recording current having the waveform shown in FIG. 4 (cl) can be produced with the configuration shown in FIG. 5.

The first and second input signals are input to a control signal generator 11 . The control signal generator 11 generates a switching control signal to operate the switch 12. When the first input signal is 11'', the control signal generator 11 determines the state of the second input signal and outputs a corresponding switching control signal to the switch 12. In other words, if the first input signal is °1 and the second input signal is °01, the switch 12 is set to side a in the figure.
If the input signal is @ll@, switch to the side shown in the figure and
This state is maintained until the input signal becomes 11° again. In other words, the time t0 of the first input signal in FIG.
sample the second input signal with pulses of '0
Since it is @, a control signal to select the a side is given to the switch 12 and held as it is until time 1. The second input signal is turned on again with the pulse (first input signal), and since it is °l'', a control signal for selecting the b side is given to the switch 12 and held as it is until time t!. The second input signal is sampled using the pulse of the first input signal, and a control signal is applied to the switch 12 according to the sample value.On the other hand, the first pattern generator 13 has a steep rise in synchronization with the first input signal. The second pattern generator 14 is synchronized with the second input signal and generates a sawtooth wave that forms a sharp jumping edge and has a slow fall.
A rectangular wave is generated that forms a rising jump edge at the same timing as the rise of the output of and a falling jump edge at the middle of the jump edge (at or near the midpoint). The output of the first pattern generator 13 supplies the above-mentioned sawtooth wave to the a-side fixed terminal of the switch 12, and the output of the second pattern generator 14 supplies the above-mentioned rectangular wave to the h-side fixed terminal of the switch 12. By controlling the switching of the switch 12 with the output of the control signal generator 11, a wave consisting of a time-series combination of the sawtooth wave and the rectangular wave is generated as shown in FIG. A recording current is obtained.

When a recording medium, such as a magnetic tape, recorded with a recording current of FIG. 4 (cl) consisting of the above-mentioned combined waves is reproduced by a magnetic head, a reproduction voltage as shown in FIG. 4 (dl) is obtained due to its differential equality.

The first and second separated signals shown in (el) and (4) of the same figure are obtained.As is clear from the figure, the first separated signal of (el) of the same figure (el) The second separated signal in the figure (fl) corresponds to the second input signal in the figure (bl).

Next, a second embodiment as an application example of the present invention will be described.

In this second embodiment, address information for each frame is recorded in a control track of a VTR (video tape recorder) on which conventionally only control signals for tracking control have been recorded, together with controller No. Ai for tracking control. The address information is used for program searches, image searches, etc.

FIGS. 6(at to 6e) show operating waveforms of the second embodiment. In this embodiment, one 8-bit word is generated within two cycles of the vertical synchronizing signal, that is, one cycle of the control signal every l frame. This is for inserting address information.

That is, the first input signal of the two types of information input to be recorded on the control track of the VTR is inserted every period corresponding to two periods of the vertical synchronization signal shown in FIG. This address code information is one of the vertical synchronization signals as shown in the figure.
It is given as serial digital data whose timing is such that 8 bits of one word are completely contained between every other pulse. In addition, the second input signal is synchronized with the rotation of the video head as shown in the figure (el).
This is a control signal consisting of a pulse train. In other words, this control signal corresponds to one pulse of the vertical synchronizing signal. In conventional devices, only positive polarity pulses of the reproduced waveform are used as control signals. Therefore, complete compatibility with conventional devices can be maintained by recording so that the control signal is reproduced as a positive pulse voltage and the information based on the address code is reproduced as a negative pulse voltage during reproduction. Therefore, the same figure (b
) and the control signal shown in FIG. 3(e), a recording current for the control head as shown in FIG.

That is, the control signal shown in the figure (el) is 11'
”, the waveform generator that generates a sawtooth wave pulse like C8 shown in the same figure (cl) is selected, and at the same time as C0 falls, the same figure (e ), select the waveform generator that generates the sawtooth wave as shown in A, and select the waveform generator co again using the next control signal 11'1, and repeat the same operation to obtain the waveform generator shown in the same figure (el). Create a sawtooth recording current as shown in .

If such a recording current is reproduced using the same control head used during recording, a reproduction voltage as shown in the figure (dt) can be obtained. From this reproduction voltage, a positive polarity pulse and a negative polarity pulse are separated, and a positive polarity pulse is generated. The pulse is used as a control signal for tracking control as in the past.Furthermore, the negative polarity pulse is used to restore the original address code based on this and is used for program search and image search.

In order to restore the address code from the negative pulse of the reproduction voltage mentioned above, for example, a clock signal for bit extraction with a period corresponding to each bit of the address code is created in synchronization with the control signal, and this is used to easily address the address code. You can restore the code. In this case, since the address code component is inserted between the control signals, there is also the advantage that there is no need to insert or extract a synchronization signal for word discrimination.

FIGS. 7(a) to (el) are operational waveform diagrams showing other specific examples of this embodiment in which the control head recording current waveforms are different from those described above; FIGS. Even if a recording current as shown in Fig. 7 (cl) is used, a reproduction voltage as shown in Fig. 6 (dl) can be obtained;
It can be implemented in almost the same way as in the case of at~(el).

FIG. 8 shows the configuration of an example of an automatic program search device for a VTR constructed by applying the second embodiment.

An outline of this application example will be explained, focusing on its function and configuration.

First, recording in the NTSC system will be explained.

Switches 21 and 22 are set to the REC side in the figure, and a tape drive system such as a capstan mechanism (not shown) sends the tape T to the right in the figure, simultaneously rotating the rotating drum 23. A video signal and a synchronization signal are recorded on the tape T by the second video head 24°25. The tape T is wound around a rotating drum 23 and fed, and the recording is performed for two tracks, that is, one frame per rotation of the rotating drum 23. A rotational position detector 26 is provided opposite the rotating drum 23, and detects a 6 II Hz pulse by detecting, for example, a 2@ magnet attached to a corresponding location on the rotating drum 23. This pulse is flip 70 knob 27
is converted into a 30 Hz square wave by

Accurately synchronizes the rotation of the rotating drum 23 with two cycles of the vertical synchronization signal of the video input signal (one rotation per two cycles of the vertical synchronization signal)
The rotating drum 23, that is, the video head 24.
The 30 Hz rectangular wave synchronized with the rotation of the speed control circuit 25 is applied to a phase detection control circuit 28, where the phase is compared with the vertical synchronization signal applied via the switch 22, and its output is sent to the speed control circuit. Given to 29. The speed control circuit 29 drives and controls the drum motor 30 for driving the rotating drum 23 in accordance with the output of the phase detection control circuit 28 . Further, the 30 Hz square wave synchronized with the rotation of the video head 24, 25 is also applied from the flip 70 knob 27 to the monostable multivibrator 31,
The output is input to the recording current generator 32. The recording current generator 32 generates a recording current as shown in FIG. 6(c) using a control signal such as, for example, el in FIG. This recording current is applied to the control head 33 via the switch 21.

In this way, recording on the control track of the tape T is performed.

Next, a case will be described in which a program search is performed using address information based on the address code when reproducing a tape on which recording has been performed on the video track, control track, etc. as described above.

First, start with the address corresponding to the desired program (hereinafter referred to as "
"selected address". ) and input it to the address comparison circuit 34, and switch 21 and 22 to 5EARCI.
(side).The reel motor control circuit 35 operates in response to an access start signal given from an operation unit (not shown), and the reel motor 36 on the supply reel side and the reel motor 31 on the winding 1 noll side are activated. For example, in the forward direction (increasing direction of address value), the address value is set so that the address value increases sequentially every l frame in the forward direction.
It is assumed that this has been set in advance. ), the control head 33 reproduces the control track, and the address signal extraction circuit 38 extracts the address signal. The address signal read out in this way (the address at that time) is compared with the selected address in the address comparison circuit 34, and if the value of the selected address is larger, the signal is run in the forward direction until the two match, and the selected address is If the value is smaller, the traveling direction is immediately reversed and a search is performed in the opposite direction. When the read address matches the preset selected address, the address comparison circuit 34 sends the reel motor control circuit 3 to the reel motor control circuit 3.
A stop signal is given to 5, and tape feeding is stopped. At this time, if the tape T has gone too far, it is corrected by a circuit not shown and the search is completed. If normal playback is performed in this state, playback will start from the specified address.

In this way, even in a VTR that does not have a dedicated track for program search, the control track and control head can be used to record/record absolute addresses for program search in correspondence with the video signal without affecting the control signal. Can be played. Therefore, it is possible to quickly and accurately access a desired program using the absolute address information while maintaining complete compatibility with conventional VTRs. Furthermore, since the control signal component can be used as a synchronization signal for address signal extraction, address extraction can be performed easily and reliably.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

For example, in each of the above embodiments, a case has been described in which two types of binary information, that is, information of "1", '0° and information of "t/@, I□°" are recorded/reproduced on the same track. It is also possible to record/reproduce information consisting of 3-value information of 1°19°'O@, J71.In other words, in that case, it is necessary to make 11I correspond to the positive polarity pulse @1'° and the negative polarity pulse l. Preferably, such ternary digital information has a substantially higher information density than binary information (higher density recording can be realized).

〔Effect of the invention〕

According to the present invention, it is possible to provide a magnetic recording/reproducing method that can easily record/reproduce two types of binary information or a single ternary information on a single recording track.

[Brief explanation of the drawing]

Figure 1 (al, (bl) is an operation waveform diagram for explaining the prior art, Figure 2 (fal, (bl) and Figure 3 (
at, (bl is a waveform diagram for explaining the present invention in detail, FIG. 4 is an operation waveform diagram for explaining the first embodiment of the present invention, and FIG. 5 is a waveform diagram for explaining the first embodiment of the present invention. Block diagram showing an example of a configuration for creating a recording current, No. 6
Figures (a) to (el) are operation waveform diagrams for explaining the second embodiment of the present invention, and Figures 7 (a) to (e) are examples of different recording current waveforms in the same embodiment. FIG. 8 is a schematic block diagram showing the configuration of a specific application example using the same embodiment. 11... Control signal generator, 12, 21. 22. ...Switch, 13.14...Pattern generator, 23...
Rotating drum, 24.25...video head, z6...
- Rotational position detector, 27. ...Flip-flop, 28
... Phase detection control circuit, 29 ... Speed control circuit, 3
0... Drum motor, 3I... Monostable multivibrator, 32... Recording current generator, 33... Control head, 34... Address comparison circuit, 35...
- Reel motor control circuit, 36. 37... Reel motor, 38... Address signal extraction circuit. Applicant's agent Patent attorney Takehiko Suzue, Commissioner of the Patent Office
Kazuo Wakasugi 1. Indication of the case Japanese Patent Application No. 57-151225 2 Name of the invention Magnetic recording and reproducing method 3 Person making the amendment Relationship to the case Patent applicant (240) Sansui Denki Co., Ltd. No change) 101-

Claims (1)

[Claims] When recording to and reproducing from a nuclear magnetic recording medium via a magnetic head that moves relative to the magnetic recording medium, a time-series combination wave of a sawtooth wave and a rectangular wave or a sawtooth wave is used as a recording signal. The jump edges in different directions of the recording signal wave are recorded in correspondence with different digital value information, respectively, and during reproduction, a differential output of the recording signal is obtained from the magnetic head to record the jump edges in different directions. The above-mentioned digital value information is extracted as positive and angular pulses respectively, and the above-mentioned digital value information is discriminately detected based on these signals, and digital information consisting of ternary information or two types of binary information is recorded/reproduced on a single recording track. A magnetic recording and reproducing method featuring: