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1. * GB780101 (A)
Description: GB780101 (A) ? 1957-07-31
Improvements in or relating to magnetic tape record carriers pressed against
a magnet head by spring blades
Description of GB780101 (A)
PATENT SPECIFICTION
Date of Application and filing Complete
Specification: April 25, 1955.
780,101 No. 11869/55.
] fApplication made in Netherlands on April 28, 1954.
/V Complete Specification Published: July 31, 1957.
Index at acceptance:-Class 40(2), D3(A2:r.1AJG1 B).
I nteunationai Classification:-Gl0j.
COMPLETE SPECIFICATION
Improvements in or relating to Magnetic Tape Record Carriers pressed
against a Magnet Head by Spring Blades We, PHiLiPs ELECTRICAL
INDUSTRIES LInITED, of Spencer House, South Place, Finsbury, London,
E.C.2, a British Company, do hereby declare the invention, for which
we pray that a patent may be granted to us, and the method by which it
is to be performed, to be particularly described in and by the
following statement:-
The invention relates to a magnetic tape record carrier and resilient
means therefor, comprising spring blades, pressing the carrier against
a magnet head.
It is already known to have such resilient means constituted by a
spring blade which exerts pressure on the carrier by way of a body,
for example of felt. Such a construction has the advantage that the
distance of the carrier from the gap of the magnet head remains
constant to a greater extent, which is of great importance for the
recording and reproducing process.
Moreover, the pressure may be utilized for keeping the carrier taut by
disposing the contact area of the resilient member with the carrier on
the opposite side of the magnet head gap from that of the driving
reel. If, in this case, the carrier travels with a certain curvature

2. over the magnet head, the tension of the carrier thus obtained will be
favourable to the recording and reproducing process owing to the
constancy of the distance between carrier and gap.
During operation the carrier will be drawn along the body of soft
material, for example felt. This material is provided between the
carrier and the resilient member in order to avoid damage to the
carrier, the resilient member being, usually, made of spring metal.
Under certain conditions, for example if the carrier is very dry, a
series of discontinuities are produced in the friction between carrier
and the body of soft material, which may give rise to vibration
resonance of the body. Such a resonating body may produce not only
acoustical energy in the form of a [Price 3/6] whistle, but also a
magnetic recording of such frequencies on the carrier. It will be
obvious that both these phenomena are to be regarded as disadvantages
in the recording and reproduction of the magnetic records. 50 In order
to mitigate these disadvantages, according to the invention vibration
damping is provided between the spring blades.
Although the use of the vibration damping properties of certain
materials is known for 55 avoiding the resonance of bodies, the
invention is based on the recognition of the fact that it is found to
be possible to obviate the frequent occurrence of relaxation
oscillations, which is a typical difficulty with magnetic 60 recording
and reproduction, by increasing the number of spring blades and by
interconnecting them with damping material.
In a particular embodiment of the resilient member according to the
invention the 65 spring blades extend parallel to one another and are
secured at one end to a common supporting body.
The invention will be described with reference to two embodiments
shown in the 70 accompanying drawing; Fig. 1 shows a resilient member
according to the invention, in which two spring blades disposed side
by side, across the width of the carrier exert pressure in the same
plane 75 against the carrier to press it against the magnet head andl;
Fig. 2 shows a sectional view of the spring blades taken on the line
T-1TI of Fig. 1.
Fig. 3 shows a further embodiment, in 80 which the two spring blades
disposed in the same plane as the carrier are placed one above the
other and are secured to one another by means of damping material.
Fig. 1 shows a resilient member according 85 to the invention urging a
magnetic tape record carrier 1 against the magnet head 2 of an
apparatus associated with the carrier.
The head is shown in a front view together with the gap. The resilient
member corm- 9 780,101 prises two spring blades 3 and 4, between which
vibration damping material 5, for example polyvinyl chloride, is
provided (see also Fig. 2). The spring blades 3 and 4 are parallel to

3. and integral with one another and are secured at one end to a common
supporting body 6, which body is secured to the housing (not shown) of
the apparatus. At the other end of the spring blades provision is made
of felt, not shown but the view of which is indicated by dotted lines
which provides a sliding contact between the metal spring blades, of
for example brass, and the carrier, on both sides of the gap. It is,
of course, as an alternative, possible to secure the two spring blades
separately to the apparatus.
Fig. 3 shows a further embodiment of a resilient member according to
the invention in a lateral view. The resilient member comprises two
spring blades 7 and 8, which are secured to one another on their flat
surfaces by an intervening vibration damping layer 9. At one end of
the spring blade 8 provision is made of a block of felt 10,25 through
which the resilient member exerts the pressure on the carrier, not
shown. At 11 the resilient member is clamped to the apparatus.
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