JPS63157302A - Cylinder drum - Google Patents

Abstract

PURPOSE:To reduce the tap winding angle for the stable drive and a compact design of a cylinder drum by having different rotational faces of a magnetic head for each signal and at the same time having overlapped record tracks. CONSTITUTION:The video heads 4 and 5 and the PCM audio heads 6 and 7 have the same azimuth angle and an upper cylinder drum 3 turns left. Both heads 4/5 and 6/7 revolve on the rotational faces of the same height but have a level difference (h). The general winding angle of a tape 1 is set at 190 deg. degrees and 180 deg. degrees are allocated to the video/audio signals applied to a video track 10a by heads 4 and 5. While rotational angles are overlapped to the track 10a by the heads 6 and 7. Thus the recording/reproducing actions are carried out by an amount equal to 31 deg. at a point behind the video head switching position by (t) deg.. The heads 4 and 7 and heads 5 and 6 from a single continuous track respectively. Thus it is possible to reduce the tape winding angle and then to decrease the drive load with a cylinder drum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a cylinder drum in a VTR (video tape recorder), particularly an 8 mm VTR.

(Prior Art) Various standards have been established for 8 mm VTRs, and the standard shown in FIG. 6 has been established for the tape pattern format for recording on magnetic tape. Figure 5 is the 6th
The tape wrapping around the cylinder drum currently employed to realize the format shown in the figure is illustrative.

A cylinder drum 2 is composed of an upper cylinder drum 3 that rotates once and a lower cylinder drum 8 that is fixed. Two video heads 4 and 5 are attached to the upper cylinder drum 3 at 180 degree positions.
rotates with

A magnetic tape 1 is wound obliquely around a cylinder drum 2, and signals are recorded on a video track 10 by a video head 4.5.

Arrow a indicates the scanning direction of the video head, and arrow s indicates the tape running direction.

The magnetic tape 1 is wound around the cylinder drum 2 by 221 degrees, of which about 30 degrees are allocated for recording PCM audio signals, and 180 degrees are allocated for recording video signals and FM audio signals. .

A PCM audio signal, a video signal, and an FM audio signal are recorded or reproduced by one scan of the video heads 4 and 5.

The disadvantage of the cylinder drum is that the magnetic tape 1 is wound around a large angle of 221 degrees. In the conventional VH8 and Beta standard formats, the magnetic tape 1 is wound at an angle of 190 degrees. As a result of the winding of the magnetic tape 1 having a large angle, the running load due to sliding friction and the like becomes large, which is disadvantageous in terms of stable running of the magnetic tape 1.

Also, when the magnetic tape 1 is wound around a large corner.

As shown in FIG. 5, the magnetic tape 1 wraps around to the rear of the cylinder drum 2, increasing the depth of the magnetic tape 1 running system, which is disadvantageous in terms of downsizing the VTR set.

If we focus only on the miniaturization of VTR sets,
There is also a recording-only machine in which the M audio recording is omitted and the magnetic tape is wound around the cylinder 2 at a 180 degree angle.

(Purpose) The present invention aims at stable running of the magnetic tape by reducing the corners when winding the magnetic tape around the cylinder drum while adhering to the format of the 8mm VTR standard.
The purpose is to realize downsizing of the R set.

(Structure) In the cylinder drum of the present invention, individual magnetic heads are provided for each of several types of signals to be recorded and reproduced, and the rotation plane of each magnetic head is made different, so that the rotation angle of each magnetic head for recording and reproduction is different. duplicate.

Examples will be specifically described below.

FIG. 1 is a diagram showing the arrangement of the magnetic head and the winding of the magnetic tape around the cylinder drum in one embodiment.

The rotating upper cylinder drum 3 has a pair of video heads 4,
It has four heads: 5 and a pair of PCM audio heads 6 and 7. The upper cylinder drum 3 rotates counterclockwise in the figure, and the video head 4 and PCM audio head 7
have the same azimuth angle, and the video head 5 and the PCM audio head 6 have the same azimuth angle. The video head 4 and the video head 5 have a pitch of exactly 180 degrees with respect to the center of the upper cylinder drum 3, and the PCM audio head 6 and the PCM audio head 7 also have a pitch of exactly 180 degrees with respect to the center of the upper cylinder drum 3. It has become a pitch.

Furthermore, the video head 4 and the video head 5 rotate on a rotating surface at the same height, and the PCM audio head 6 and PCM audio head 7 also rotate on a rotating surface at the same height.
The heights of the rotating surfaces of the video heads 4 and 5 and the rotating surfaces of the PCM audio head 6.7 are different, and as shown in FIG. 2, there is a step of h between the heights of the respective rotating surfaces. is attached. Reference numeral 9 denotes a lead portion that guides the lower end of the magnetic tape 1.

FIG. 3 shows the tape pattern and operating principle of the cylinder drum of this embodiment.

The total winding of the magnetic tape 1 onto the cylinder drum 2 has a corner angle of 19.
0 degrees, of which the video head 4
, 5 to the video track lOa and F
Assigned to recording/playback of M audio signals. 11 is P
This is a CM audio track, and the rotation angle is overlapped with that of the video track 10a by the PCM audio head 7.6, and the rotation angle is 31 degrees behind the video head switching position by t degrees.
Record and play back minutes. A video head 4 and a PCM audio head 7 form one track connected to each other, and a video head 5 and a PCM audio head 6 form one track connected to each other.

Video track 10a and PCM audio track 11
In order to align the positions of the video head 4.5 and the PCM audio head 6.7, the level difference between the rotating surface of the video head 4.5 and the rotating surface of the PCM audio head 6.7 must satisfy the following predetermined conditions. This condition will be explained with reference to FIG. In addition, 10
While a is the video track, 10b is the trajectory of the video head 4 when the magnetic tape 1 is stopped, and 11 is the PCM audio trunk, while llb is the trajectory of the video head 4 when the magnetic tape 1 is stopped. This is the trajectory of the PCM audio head 7 when it is running.

Let the angle formed by the axes of the video head 4 and the PCM audio head 7 be α degrees. The pitch Pac in the tape running direction between the point C where the PCM audio head 7 crosses the video head switching position 12 shown by the chain line and the switching point a of the video head 4 which is ahead by α degrees is set to match the track pitch. .

Pac=2n(Vt,/nf) must be. where n is an integer, Vt is the tape speed, and nf is the field frequency.

Further, while the video head 4 rotates by (α+β) degrees, the magnetic tape 1 advances by Pab. Pab is Pab=(α+β
) Vt/180nf. From the above formula, (2n+(α+β)/IJIO) (Vt/n f)
cosθ0=βπD/360, and n that satisfies this formula
, β can be found. here.

D is the diameter of the cylinder drum 2, θ0 is the angle of the lead part 9, and from the PCM audio track 11 β≧
It must be 31 degrees. From this, the head height difference is h = (β/360) πD tan e.

is derived.

The recording/playback start point of the PCM audio head 7 is delayed by T=α"+31@=α0+β'-t' from the video head switching position 12.

By adopting α and steps that satisfy the above conditions,
PCM audio track 11 and video track 10a
The linearity of is maintained.

(Effects) In the cylinder drum of the present invention, an individual magnetic head is provided for each of multiple types of signals recorded on a magnetic tape and reproduced from the magnetic tape. Since the rotation angles for recording and playback are made to overlap, the tape winding angle of the 8mm VTR cylinder drum can be lowered from the conventional 221 degrees to 190 degrees. This reduces the tape running load and also allows the VTR set to be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the cylinder drum and tape path in one embodiment, FIG. 2 is a developed view showing the relationship between the video head and PCM audio head in the same embodiment, and FIG. 3 is a plan view showing the cylinder drum and tape path in the same embodiment. FIG. 4 is a diagram showing the relationship between the tape track pattern and the head trajectory in the same embodiment. FIG. 5 is a plan view showing the conventional cylinder drum and tape path. FIG. 6 is the same diagram. FIG. 2 is a developed view showing the relationship between a cylinder drum and a magnetic tape in a conventional example. 1...Magnetic tape, 2...Cylinder drum. 3...Upper cylinder drum, 4.5...Video head, 6.7...PCM audio head, 8...
...lower cylinder drum. 10a...Video track, 11...PCM audio track.

Claims (1)

[Claims] (1) In the cylinder drum of a magnetic recording/reproducing device, which is equipped with a magnetic head and rotates on a magnetic tape wound at an angle to record and reproduce multiple types of signals on diagonal tracks, individual signals are recorded for each signal. A cylinder drum characterized in that a magnetic head is provided, the rotating surfaces of each magnetic head are different, and the rotation angles for recording and reproduction of each magnetic head are made to overlap.