DE1227511B - Magnetic tape recorder - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

Gilb

German KL: 21 al-37/22

Number: 1227511

File number: R 36339IX c / 21 al

Filing date: October 16, 1963

Opening day: October 27, 1966

The invention relates to a magnetic tape recorder for storing large bandwidth signals with am Circumference of a rotating head wheel arranged magnetic heads, which the magnetic tape in transverse or Smear obliquely to its longitudinal direction traces, and with a tape guide, which the Magnetic tape of the path of the head tracks and the one slot running along these tracks has into which the magnetic tape is pressed under elastic deformation by the head tips will.

In such a device, the magnetic tape is usually by a curved guide, the so-called head shoe, adapted to the path of the magnetic head. The guide points in the way of the Magnetic head has a slot, so that the contact pressure between the magnetic tape and the magnetic head by the tension and the physical properties of the magnetic tape, by the width of the slot and the amount of deformation of the magnetic tape caused by the magnetic head is determined. In known devices of this type are the slot, the properties and the voltage of the Magnetic tape stuck, while the radius of the magnetic head due to wear and tear during its life is steadily decreasing. With a new, not yet worn magnetic head, the contact pressure is between the magnetic tape and the magnetic head is greatest and therefore also the rate of wear and tear high. Over the course of the operating time, the radius of the magnetic head becomes smaller and therefore it decreases also the rate of wear and tear. Obviously, this is a disadvantage because, with minimal wear and tear, the Life of the magnetic head would be much longer.

It has already been proposed to maintain a constant contact pressure between the magnetic head and the magnetic tape by a radial displacement of the head shoe. Such an arrangement has the disadvantage that timing errors can easily occur in the recorded or reproduced signals.

It has also already been proposed to reduce the contact pressure between the magnetic tape and the magnetic head to compensate for changes in the head radius to vary in that of the magnetic tape the recorded signals to the same time as in the recorded signals. The for However, the change in the contact pressure required for this purpose increases the wear rate of the Magnetic heads.

In accordance with the present invention, in a magnetic tape recorder of the type described, the width becomes Magnetic tape recorder

Applicant: ■ -

Rank-Bush Murphy Limited, London

Representative:

Dr.-Ing. W. Lampert, patent attorney,
Stuttgart W, Breitscheidstr. 4th

Named as inventor:

John Lewis Edwin Baldwin, Croydon, Surrey;

Peter William Blaxtan,

Bromley, Kent (UK)

Claimed priority:

Great Britain October 17, 1962 (39 271)

of the slot in the tape guide perpendicular to the head track is chosen so large that the ratio of the Anas pressure between tape and head tips at the beginning and at the end of the service life of the magnetic heads is less than 2.5.

In one embodiment of the device according to the invention, the width of the slot is in the head shoe much larger than with the known devices. This ensures that the change in the contact pressure is significantly reduced in the course of the service life of the magnetic heads.

In another embodiment of the magnetic tape device according to the invention, the wide slot in the head shoe decreased during the operating time of the magnetic head and thereby the change the contact pressure between the magnetic head and the magnetic tape during the operating time of the magnetic head decreased.

In a further embodiment of the magnetic tape device according to the invention, the tape tension increased in the course of the service life of the magnetic head, in this way the change in the contact pressure during the service life of the magnetic head.

The invention will now be described in more detail with reference to the figures, which follow represent:

Fig. 1 shows schematically the effect of wear of the magnetic head in a known one Magnetic tape recorder;

609 70 & / 265

Claims (1)

3 4 Fig. 2 shows the same parts as in Fig. 1, the magnetic head is now only two and a half times as large which are designed according to the invention; like the minimum contact pressure at the end of 3 shows the same for a different drive duration of the magnetic head. management form of the magnetic tape according to the invention in the embodiment shown in FIG device; 5 of the magnetic tape device according to the invention are located Fig. 4 is a further embodiment according to itself - the - guide parts - 1 and Γ in the same the invention. . radial distance from the axis of rotation of the Fig. 1 shows a tape guide in cross section with magnetic head 4 as in the known embodiment the parts 1, 1 ', which are separated by the slot 2 according to FIG. 1. The distance between the guide parts I ₅ Γ in. The magnetic tape 3 lies on the guide in the direction of the axis of rotation, however, is between parts 1, 1 ' and is pushed into the slot 2 by the magnetic head 4 at a maximum value for a new magnetic head. The penetration depth of the magnetic (guide parts 1, Γ and magnetic head 4 in dashed head 4 in the slot 2 varies during the bed lines) and a minimum value for the operating time of the magnetic head. It is the largest, used magnetic head {guide parts 1 ", Γ" and if the magnetic head is new and not yet worn 15 gnetkopf 4 in solid lines) changed. The width of the slot becomes larger and smaller in the course of the service life, as a result of the wear and tear of the magnetic head. If the ratio to the width of the magnetic head is selected, the position of the magnetic head and the magnetic tape can be achieved in such a way that the deflection angle α of the broken line 5 relates to a new magnetic tape for a new magnetic head and the magnetic head, the representation in solid lines 6 20 angle β for a worn magnetic head equal to a magnetic head at the end of its life, is large. The range of variation of the slot width can, for the sake of clarity, be significantly greater than or smaller than this optimum amount, and it is exaggerated. In the known illustrated in Fig. 1 there is a certain advantage of the pray device behaves.sich, the angle α, around which the tape was written. In the embodiment of the invention according to angle β for a "worn magnetic head about Fig. 4, the distance between the guide parts 1, Γ and 6: 1 remains. So that the width of the slot 2 in the course of viewing the material, the pressure that is unchanged by the material on the operating time of the magnetic head 4, so that the object is exerted which causes the deflection of the deflection angle α for a new magnetic bending, approximately proportional to the 30 head (dashed lines) to the angle β for a deflection angle can be assumed, worn magnetic head (solid lines) this indicates that the pressure between the magnetic changes in the ratio 2: 1. However, the chip tape and the magnetic head During the operating time of the magnetic tape, which are also varied by the transport of the magnetic head in a ratio of 6: 1, 8.8 'on the tape and the supply reel (not iert. Since the tape dzug in the known magnetic tape recorder 35) is exercised while the operating time is constant, this must be selected so large that the duration of the magnetic head is changed and on this also on a heavily worn magnetic head on the way the change of the contact pressure between the end of its operating life from the magnetic tape on - Magnetic head 4 and magnetic tape reduced. The changing the pressure is exerted. Therefore, the pressure exerted by the tape tension is preferably applied in a new magnetic head to such an extent that the pressure six times as great as would be required per se, the pressure of the magnetic tape on the magnetic head and the rate of wear is thereby substantially increased the service life of the magnetic head increases it substantially and the life of the magnetic head remains constant. You can also shorten this unnecessarily. Way, the ratio of the maximum to the minimum In the embodiment of the 45 according to the invention, substantially reduce the contact pressure so that e.g. Magnetic tape device in F i g. 2 are the parts that are not greater than 1.5: 1. The tape guide 1,1 'is much further apart from one another. It is also possible to use the farther than in the known embodiment according to FIG. 1, the described embodiments to be so that the slot is two to three times as wide as turning, e.g. B. can the movement of the guide parts in the known device. The guide 1, 1 'is also 50 to change the slot width with a corresponding in the radial direction against the axis of rotation for the variation of the belt tension. Magnetic head 4 moved so far that the smallest Angle β is about the same as in the known claims:
Device according to FIG. 1. In this way, the same 1st magnetic tape device is obtained for the storage of minimal contact pressure between the magnetic head and 55 gnalen of a large bandwidth with a constant tape tension on the circumference of a magnetic tape. While rotating head wheel arranged magnetic trend of the slot in the other devices of this type heads, which the magnetic tape in transversely or not larger than 0.125 inches (about 3.1 mm), it will run obliquely to its longitudinal direction in the embodiment of the invention after tracks coat, and with a tape guide, Fig. 2 to 0.25 to 0.3 inches (about 6.2 to 7.5 mm) 60 which increases the magnetic tape of the path of the head tips, together with a corresponding adapter and the one along this path reducing the radius of the guide. In this way running slot, in which the magnet is achieved that the change of the angle and tape is pressed under elastic deformation by the thus the contact pressure between the magnetic head and head tips, thereby geMagnetic tape is significantly reduced, e.g. from 65, that the width of the slot 6: 1 to 2.5: 1, whereby a substantial demand in the tape guide perpendicular to the head track so tion of the life of the magnetic head is achieved large is chosen that the ratio of the application, since the maximum contact pressure with a new pressure between the tape and tips of the head on At the beginning and at the end of the service life of the magnetic heads is less than 2.5. 2. Magnetic tape recorder according to claim 1 for storing television signals with four in equal angular distances on a head wheel with S magnetic heads about 50 mm in diameter and a band guide concentrically surrounding the head wheel over part of its circumference, characterized in that the width of the slot in the tape guide is substantial larger, preferably two to three times as large as the previously usual slot width (approx 3 mm). 3. Magnetic tape device according to claim 1, characterized by means which the width of the Slot in the tape guide as the magnetic heads wear out in the course of their Reduce the service life so that the deflection angle («, /?) Of the magnetic tape approximates remains constant. Considered publications: German Auslegeschrift No. 1049 904;
Telecommunications, 9 (1959), issue 4, p. 181
186. 1 sheet of drawings 609 70a / 265 10.66 © Bundesdruckerei Berlin