JPS5911512A - System for feeding recording medium in helical scanning system - Google Patents

Abstract

PURPOSE:To form a recorder/reproducer without uneven running due to stick/ slip compact, by driving intermittently a capstan with a stepping motor for feeding intermittently a recording medium such as magnetic tape. CONSTITUTION:When a contact angle alpha of the magnetic tape 4 is 90 deg. to rotary heads 2a, 2b provided at positions opposite to each other, the stepping motor 15 is turned by one step only in synchronizing with a period when an area of hatched lines of a rotary drum 1 contacts the magnetic tape 4, the magnetic tape 4 is fed for one track's share via the capstan 14, and the magnetic tape 4 is stopped at the next area, i.e., for the period when the magnetic head 2b scans the magnetic tape 4. A signal Sa reproduced and recorded with the magnetic head 2a and a signal Sb recorded and reproduced with the magnetic head 2b are inputted and outputted alternately at an interval of 90 deg. with each other, a pulse P driving the stepping motor 15 has only to be applied in synchronizing with the signal just after the signals Sa, Sb, and it is possible to feed the tape less than 90 deg. at the interval between the signals Sa and Sb, i.e., the area of hatched lines, allowing to extend the recording and reproducing period for the share.

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 rotary head.

PCM (Pulse Code)
A helical scan type magnetic recording/reproducing device using a rotary head has been put into practical use as a method for recording/reproducing digital information by converting it into a modulation signal.

This PCM magnetic recording and reproducing device records and reproduces video signals.
Similar to a VTR for playback, rotating magnetic heads placed at 180 degree intervals on the slanted trunk alternately play audio PCs.
It records (reproduces) M signals and is suitable for high-density recording, but when the recording track width is narrowed to increase the utilization rate of the magnetic tape as a recording medium, the running speed of the magnetic tape naturally decreases. I will do it.

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 the like, 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 the above problem, the present invention makes use of the characteristics of recording and reproducing using PCM signals, and uses a stepping motor to drive the capstan intermittently.

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 J word of the PCM signal and interleaving in units of several words. A memory that can store several words of a PCM signal as one block is used to record the PCM signal on the U memory or reproduce the PCM signal.
Data processing is performed by temporarily storing CM signals and sequentially reading them out.

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

Therefore, in the present invention, paying attention to this point, the magnetic tape is configured to be fed intermittently, thereby eliminating the running unevenness caused by stick-slip as described above.

FIG. 1 shows an embodiment of the present invention, in which 1 is a rotating drum, 2 is a rotating head disposed coaxially with the rotating drum 1, and includes a rotating head 2a for the A trunk and a rotating head 2a for the B trunk. The rotating heads 2b are provided at intervals of 80 degrees. 3 is a cassette half in which the magnetic tape 4 is stored, 5.6 is a supply reel and take-up reel for the magnetic tape 4, and 7.8 is a tape guide ruler.

9.10 is the tape guide provided on the deck side, l
L12 is a magnetic tape 4 attached to the rotating drum 1 at a certain angle.
They are an entry guide ρ-ra and an exit guide p-ra that guide the. It should be noted that on the running path of the magnetic tape 4, a tensioner 7-m, a p-ra for -1 dig/g, etc. are arranged as necessary.

Reference numeral 13 denotes a pinch ruler, which presses the magnetic tape 4 together with the capstan 14 and causes the magnetic stave 4 to travel. The capstan 14 is intermittently driven to rotate by a stepping motor 15 indicated by a dashed line.

In addition, capstan 14. A dual capstan system may be used in which the pinch ρ-ra 13 is also provided on the tape inlet side. Further, as shown by the dotted line, the guide roller 10 is made movable by a tension member 16, and the length of the capstan 140 point and the point where the magnetic tape 4 first contacts the magnetic head are adjusted by a mechanism not shown. You can.

The characteristic feature of Rammei's tape feeding system is that in order to run the magnetic tape 4 intermittently, in the case of two rotating heads 2a and 2b, the angle α at which the magnetic tape 4 contacts the rotating drum 1 is within 180°. The motor that drives the capstan 14 for feeding the magnetic tape 4 is a stepping motor 1 that rotates by one constant angle with a pulse.
This point is considered to be 5.

Figure 2(a) shows a rotating head 2a installed at a 180° position.
, 2b, the contact angle α of the magnetic tape 4 is 90°. In this case, in synchronization with the period in which the hatched area of the rotating drum 1 is in contact with the magnetic tape 4, the stemming motor 15 rotates by one step and transfers the magnetic tape 4 one trunk through the capstan 14. After minute advance, the magnetic tape 4 is kept in a stopped state during the next area, that is, the period during which the magnetic head 2b scans the magnetic tape 4.

FIG. 2(b) shows the recording trunk of the magnetic tape 4 when the tape feeding method is used, and the inclination angle θ of the recording (reproduction) track is determined by the angle of the tape entering the rotating drum 1. A and B tracks having different gamma angles are alternately formed. The width of the recording (playback) track is W,
Assuming that the inclination angle is θ, it can be seen that after scanning the track, the motor becomes a stepping motor, and when θ is small, ΔS=■.

FIG. 3 shows the signal relationship for performing a crawling tape feed. The signal S reproduced (recorded) by the magnetic head 2a and the signal Sb recorded (reproduced) by the magnetic head 2b are shown in FIG. The signals are input (output) alternately at intervals of 90 degrees.

Therefore, the pulse P for driving the stepping motor 15 only needs to be supplied synchronously immediately after the signals S a and sb (and the tape feeding should be completed by the next scanning period).

Therefore, the interval between signals s1 and sb, that is, the second
The shaded area shown in Figure (a) can be made less than 90' if the tape is fed in a short time, and the recording (playback) period can be made that much longer, that is, closer to 180°. will be possible.

FIG. 4 shows an embodiment in which the tape feeding system of the present invention is extended to three heads.

Rotating magnetic heads 21 a, 2 l b, 21
c are spaced 120" apart and have a tape contact angle of 60'
The case is shown below.゛In this case, the tape is fed during the shaded period, and each rotating magnetic head 21a, 21b.

The input/output signals of 21c are supplied at 60° intervals.

In this embodiment as well, if the tape can be fed quickly, it goes without saying that the tape stop range, that is, the scanning period can be set to a range larger than 60' and smaller than 120°.

Note that the rotary head 2 with respect to the track of the magnetic tape 4-
In order to correct the tracking error of a and 2b, the tracking error signal is detected from the reproduced signal so that the detected PCM pulse waveform becomes the maximum, and the tension 7-
The displacement of Al6 may be controlled.

As explained above, the recording medium feeding method in the helical scan method of the present invention utilizes the recording/reproducing characteristics of PCM signals to intermittently feed a recording medium such as a magnetic tape. There is no need for a 7spg control circuit as seen in conventional analog pgservers, and most of the electronic circuits can be constructed with digital ICs.

Furthermore, since a CTL signal is not particularly required, there is an advantage that the recording/reproducing apparatus can be formed compactly.

[Brief explanation of drawings]

2(a) is a diagram for explaining the contact angle between the rotary head and the magnetic tape; FIG.
b) is an explanatory diagram showing the relationship between the recording track of the magnetic tape and the feed amount, FIG. 3 is an e-shaped diagram of the recording (reproducing) signal and the driving pulse of the stepping motor, and FIG. 4 is a diagram showing another embodiment of the present invention. FIG. 3 is an explanatory diagram of a rotating head. In the figure, 1 is a rotating drum, 2a and 2b are rotating heads, and 13
14 represents a pinch ruler, 14 represents a capstan, and 15 represents a stepping motor. Figure 1 1 Figure 2 (a) Figure 2 (b) Figure 4 1c

Claims (1)

[Claims] In a device that records and reproduces 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 determined by the number of rotating heads that are not in contact with the recording medium. A recording medium feeding method in a helical scan method characterized by intermittent feeding for each track.