JPH0359482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording medium feeding system for recording or reproducing digital information using a helical scan method using a rotating head.

Audio signals etc. are converted to PCM (Pulse Code).
A helical scan type magnetic recording and reproducing device using a rotating head has been put into practical use as a method for recording and reproducing digital information by converting it into a modulation signal.

This PCM magnetic recording and reproducing device records (reproduces) audio PCM signals alternately using rotating magnetic heads arranged at 180 degree intervals on an inclined track, similar to a VTR that records and reproduces video signals.
Although it is suitable for high-density recording, if the recording track width is narrowed in order to increase the utilization rate of the magnetic tape as a recording medium, the running speed of the magnetic tape will naturally decrease.

When the amount of magnetic tape fed within a unit time decreases, the coefficient of friction between the magnetic tape and the guide changes slightly, resulting in stake slip and other problems, resulting in uneven feeding speed. This makes it difficult to servo the capstan in an analog manner as in the past.

In order to solve such problems, this invention
Taking advantage of the recording and playback characteristics of PCM signals,
The capstan is driven intermittently by a stepping motor.

Hereinafter, a mechanism for recording and reproducing audio PCM signals on a recording medium using magnetic tape according to the present invention will be explained.

When converting an audio signal into a PCM signal and recording it on a magnetic tape, processing is usually performed such as attaching an error detection code to each word of the PCM signal and interleaving in units of several words. A memory capable of storing several words of a PCM signal as one block is used, and data processing is performed in which the PCM signal recorded in the memory or the reproduced PCM signal is temporarily stored and sequentially read out.

Therefore, it is not necessary to continuously reproduce or record the PCM signal at a constant speed as seen in video signals.

In view of this, the present invention has a structure in which the magnetic tape is fed intermittently, thereby eliminating the running unevenness caused by staple slips and the like as described above.

FIG. 1 shows one embodiment of this invention.
2 is a rotating drum, and 2 is a rotating head disposed coaxially with the rotating drum 1, including a rotating head 2a for the A track and a rotating head 2b for the B track.
are placed at 180 degree intervals. 3 is magnetic tape 4
5 and 6 are respectively supply reels and take-up reels for the magnetic tape 4, and 7 and 8 are tape guide rollers.

9 and 10 are tape guides provided on the deck side; 11 and 12 are entrance guide rollers that guide the magnetic tape 4 at a constant angle to the rotating drum 1;
and an exit guide roller. It should be noted that a tension arm, a loading roller, and the like are arranged outside the running path of the magnetic tape 4 as necessary.

13 indicates a pinch roller, and a capstan 14
At the same time, the magnetic tape 4 is pressed and the magnetic tape 4 is run. The capstan 14 is intermittently rotated by a stepping motor 15 indicated by a dashed line.

Note that a dual capstan system may be used in which the capstan 14 and the pinch roller 13 are also provided on the tape inlet side. Further, as shown by the dotted line, the guide roller 10 is movable by the tension arm 16, and the point of the capstan 14 is moved by a mechanism (not shown).
The length of the point where the magnetic tape 4 first contacts the magnetic heads 2a, 2b may be adjusted.

As can be seen from the above description, the tape feeding system of the present invention is characterized by the use of two rotary heads 2 in order to intermittently run the magnetic tape 4.
In the case of a and 2b, the magnetic tape 4 is attached to the rotating drum 1.
The angle α at which the magnetic tape 4 touches is set within 180°, and
A stepping motor 15, which rotates by a certain angle with one pulse, is used as the motor for driving the motor. Further, the rotary head 2
Points a and 2b are points on the circumferential surface of the rotary drum 1 that are provided with a step W corresponding to approximately one track.

FIG. 2a is a side view showing the positional relationship between the rotating heads 2a, 2b attached to the rotating drum 1 and the magnetic tape 4.
The two rotary heads 2a and 2b are arranged with a step W of approximately one track on the circumferential surface of the rotary drum 1.

FIG. 2b shows the positional relationship between the rotating heads 2a, 2b and the magnetic tape 4 viewed from above. The case of ゜ is shown. In this case, the area indicated by diagonal lines is the rotary head 2a,
Since both 2b and 2b indicate positions where the magnetic tape 4 is not in contact with the magnetic tape 4, the magnetic tape 4 is
By intermittently feeding the tracks, two recording (reproduction) tracks A,
B can scan the magnetic tape 4 in a stationary state.

FIG. 2c shows the tracks recorded on the magnetic tape 4 when such a tape feeding method is used, and the inclination angle θ of the recording tracks is the same as the second one described above.
It is determined by the angle of the tape entering the rotating drum 1 in figure a.

If the width of the recording (playback) track is W, then the tape feed amount ΔS per time sent by the slapping motor 15 is ΔS = 2W/sinθ, and if θ is small, approximately ΔS = −2W/θ. I know it's good.

Figure 3 shows the signal relationship for performing such tape feeding, and shows the signal S _a recorded (reproduced) by the magnetic head 2a and the signal S a recorded (reproduced) by the magnetic head 2b. The signals S _b are input (output) alternately at intervals of 90 degrees.

The pulse P for driving the stepping motor 15 may be supplied in synchronization immediately after the signal S _b , and the tape feeding may be completed at least before the next signal S _a is recorded (reproduced). Note that the pulse P is the signal S _b
It is also possible to feed the magnetic tape 4 synchronously immediately after the magnetic tape 4. In either case, it is sufficient to feed the magnetic tape 4 by one step, that is, by the length ΔS of two tracks, during one rotation of the rotating drum 1. Become.

Therefore, according to the present invention, it is sufficient to drive the stepping motor 15 in one step with one rotation of the rotary drum 1, so that a synchronous relationship can be easily established.

In addition, in order to correct the tracking error of the circuit heads 2a and 2b with respect to the track of the magnetic tape 4, the displacement of the tension arm 16 described above is controlled so that the PCM pulse waveform detected by the rotary head 2a or 2b becomes maximum. You may also do so.

As explained above, the recording medium feeding method in the helical scan method of this invention is based on the PCM
Utilizing the characteristics of recording and reproducing signals, we have made it possible to intermittently feed a recording medium such as magnetic tape once per revolution of the rotating drum. Since no control circuit is required, most electronic circuits can be constructed from digital ICs. Moreover,
Since a CTL signal is not particularly required, there is an advantage that the recording/reproducing device can be formed compactly.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the recording medium feeding method in the helical scan method of the present invention, and FIG. 2a
2 is an explanatory diagram showing the position of the rotating drum and the rotating head, FIG. 2 b is an explanatory diagram showing the contact angle between the rotating head and the magnetic tape, and FIG. 2 c is an explanatory diagram showing the relationship between the recording track of the magnetic tape and the feed amount. 3A and 3B are waveform diagrams of recording (reproducing) signals and driving pulses of the stepping motor. In the figure, 1 is a rotating drum, 2a and 2b are rotating heads, 13 is a pinch roller, 14 is a capstan,
15 indicates a stepping motor.

Claims (1)

[Scope of Claims] 1. In an apparatus for recording and reproducing digital signals on a recording medium using a helical scan method, the contact angle α of the recording medium wound around a rotating drum is 360°/n or less with respect to the number of rotating heads n. and each of the at least two rotary heads provided at equal intervals,
The recording medium is placed with a step difference of one track, and during the period when each of the rotary heads is not in contact with the recording medium, the recording medium is placed on one of the rotary heads.
A method for feeding a recording medium in a helical scan system, which is characterized by feeding only one step per rotation.