Note: Descriptions are shown in the official language in which they were submitted.
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THIS. INVENTION relates to improved apparatus
for cleaning the playing and/or recordin~ head(s) of a
video tape player/recorder. In particular, the invention
is directed to an improved VCR (video cassette recorder)
head cleaning cassette.
There are many known devices for cleaning the
heads of video recorders, and examples can be found in
Australian patents nos. 538554, 541655, 545853, 570527
and Australian patent application no. 72022/87. These
VCR head cleaners are normally in the form of a cassette
having a cleaning tape mounted on a pair of spools
therein. When the cassette is inserted into the VCR, the
cleaning tape is brought into contact with the head to be
cleaned. The head is cleaned by virtue of the rotation
of the head surface against the cleaning tape as a
consequence of the actuation of the ~PLAY" command of the
VCR.
Ano~her example of such VCR head cleaners is
the VH-295 vldeo head cleaner sold in Australia by Kyowa
Sonic Co., Ltd.
However, it has been found that known VCR head
cleaners are not suitable for all VCRs. In particular,
it has been found that known VCR head cleaners are not
suitable for some of the new VCRs such as so-called
~quic~-load" or "half-load" VCR machines. When a known
head cleaning cassette, such as the Kyowa VH-295 head
cleaner, is inserted in quick-load or half-load machines,
the cleaning tape is pulled from the cassette housing to
a greater extent than its design specifications would
normally permit.
The operating components of VCRs are very
sensitive, and lf a splndle or other operating component
senses a reslstance to rotation greater than a certain
level, this wlll normally actlvate a shut-off mechanism
in the VCR. The use of known cassette cleaners in quick-
load or half-load machines often causes the VCR to shut
down on the assumption that there is a stuck tape in the
VCR machine. Consequently, the VCR must be taken apart
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and recalibrated.
Cleaning cassettes which are designed
specifically for use with quick-load or half-load
machines are normally not suitable for use with
conventional VCRs.
It is an object of the present invention to
overcome the abovedescribed problem by providing an
improved video cleaning cassette which has universal, or
at least wide, application to VCRs.
In one broad form, the present invention
provides apparatus suitable for cleaning a head of a
video player/recorder, the apparatus comprising a
cassette housing having a length of resiliently tensioned
cleaning tape mounted thereon in a suitable manner,
characterised in that the effective length of the tape is
greater than 200mm, and preferably between 220mm and
245mm.
The~effective length of the tape ls suitably
about 233mm.
Typically, the cleaning tape is a chamois
ribbon having one end secured in a slot in the front face
of the cassette and its other end secured to one end of a
coil spring within the cassette housing, the other end of
the coll spring being connected to a fixed point in the
housing. The cleaning tape passes at least partially
around a spool in the cassette.
The "effective length~ of tape is defined as
that length of tape extending from the fitting by which ;~
it i8 connected to the coil spring, to the slot in the
front face of the cassette housing in which the end of
the tape is secured. This is approximately the length of
tape pulled out of the cassete housing during cleanlng
actlon.
It has been found that the use of a cleaning
tape having a length between 220mm and 245mm, and
preferably 233mm, renders the cleaning cassette
particularly suitable for use with quick-load or half-
load machines. This tape length is longer than normal.
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Whereas the uæ of a longer cleaning tape would normally
lead to problems in using the cassette on conventional
VCRs, the cleaning tape of this invention avoids such
problems by being tensioned lengthwise by the coil
spring. More specifically, the tape is provided with a
higher than normal tension so that when used with
conventional VCRs, the tape will not be pulled out
excessively from its housing. Preferably, the coil
spring is selected, or the tape is otherwise tensioned,
10to have a tension of between 0.75 Newton to 1.2 Newton
when fully extended. Typically, the coil spring is
selected to prov~de a tension of between 0.8 and 1 Newton
in the tape. In the preferred embodiment, the tension
provided in the coil spring is about 0.8N.
15The use of a longer cleaning tape renders the
cleanlng cassette of this invention suitable for use in
quick-load or half-load machines, while the use of higher
tension in t~e tape enables the cleaning cassette to
retain its suitability for use in conventional VCRs. To
accommodate the longer cleaning tape, the diameter of the
spool around which the tape passes is larger than the
conventional spool.
The cleaning tape may suitably be used in ~wet~
form, i.e. with cleaning fluid applied thereto. A "dry
cleaning tape portlon may also be provlded for use ln
con~unctlon with the ~wet" tape.
In order that the lnvention may be more fully
understood and put into practice, a preferred embodiment
thereof will now ~ described by way of example, with
reference to the ~companying drawings in which:
Fig. l ls a diagrammatic plan view of the
cleaning cassette of~one embodiment of this lnvention in
use, and
Fig. 2 ~8 a partlal sectlonal plan view of the
cleaning cassette of Fig. l when not in use.
As shown in Fig. 1, the video head cleaner lO
of one embodiment of this invention comprises a cassette
housing 11 having a pair of spools 12, 13 therein.
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Preferably, no-teeth are provided on the hub of spool 13.
A first length of cleaning tape has one end connected to
spool 12 and its other end held in a slot 15 in the front
face 16 of the cassette housing 11. This first length of
tape 14 is normally intended to be used in "dry" form.
The tape may suitably be a chamois ribbon.
A second length of cleaning tape 17 also has
one end secured in slot 15 on the front face 16 of
cassette housing 11. The other end of tape 17 is
connected to an end fitting 18. A coil spring 19 extends
between the end fitting 18 and a fixed securement 20
within the cassette housing 11. The second length of
tape 17 is normally used in "wet" form, i.e. cleaning
fluid is applied to the operative portion of this tape,
15 for example through an aperture in the cover over the ~;
front face of the cassette. The tape 17 is suitably a
chamois ribbon. ~ ~
Normally, the tapes 14, 17 are retracted as ;
shown in Fig. 2.
The spool 12 has a toothed perlpheral edge 38
which 18 engaged by a pawl on the end of a pivoted
detente arm 39. The spool 12 ls thereby prevented from
rotatlng. The detente arm 39 has another arm portlon
thereof ln contact wlth a plvoted L-shaped flap 40. When
the flap 40 18 ralsed, the arm 39 pivots to release the
pawl from the toothed edge 38.
There 18 no need to describe the operation of i
the VCR in detail as such operation is already well
known. However, a brief descrlption of the relevant
30 operatlng components of the VCR is given below to assist -
the understanding of the operation of the head cleaner
10. ~ '
There are typlcally three magnetlc operatlng
components which either respond to the magnetic signals
on a video tape, alter the magnetic signal on the tape,
or do both. These magnetic operating components are an ~;
erase head 31, a vldeo drum with a playing head 32, and
an audio head 33.
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The VCR also comprises a number of mechanical
components which operate directly on the tape to properly
position the tape in the operating mode, and also to move
the tape along its operating path. These mechanical
components include a capstan 34 and associated pinch
roller 35, guide rollers 36, 37, 46, and moveable guide
members designated 47-52.
In use, the guide members 47-52 engage the back
side of the video tape and move it outwardly of the
cassette housing 11 into the playing position shown in
Fig. 1.
The VCR has a first drive sprocket which fits
into the centre portion of the right spool 13 (but does
not engage the spool 13 as the teeth in the hub of that
spool are preferably removed or omitted), and a second
take-up sprocket whlch fits through the centre of the
left spool 12 in a spline fit.
When the cle~ning tape 10 is first placed in
the cassette socket of the VCR, the tapes 14, 17 are as
shown in Fig. 2. The flap member 40 is lifted by the VCR
to cause detente arm 39 to release the pawl from the
toothed edge 38 and allow spool 12 to rotate.
Once the VCR is placed in PLAY mode, the guide
members 47-52 move the cleaning tapes 14, 17 outwardly
lnto contact wlth the heads 31, 32, 33 as shown ln Flg.
1. The spool 12 18 free to rotate to accommodate the dry
tape 14 belng pulled out of the cassette housing 11. The
wet tape 17 however, i8 pulled out of the housing 11
against the tenslon of the spring 19. The drlve sprocket
ln spool 13 does not drive the spool as the hub teeth are
not present and there is no engagement between sprocket
and spool. (However, if the teeth on the hub of spool 13
are present, the drive sprocket may cause spool 13 to
rotate, but lt wlll simply rotate agalnst the sprlng 19
without affectlng the operation of the tape 17).
The video drum playing head 32 rotates against
both the wet and dry tapes 14, 17 to effect a self-
cleaning action.
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The engagement of the tapes 14, 17 against the
erase head 31, and audio head 33, respectively, also
assists in the cleaning of those heads.
The tape 17 has an effective length of between
220mm and 245mm, and preferably 233mm. The effective
length is measured along the tape 17 from the inner edge
of slot 15 to the connection fitting 18. This is roughly
the length of tape pulled out of the cassette during
cleaning. The longer than normal length of the tape 17
renders it suitable for use with quick-load or half-load
machines.
The spring 19 is selected to provide a tension
of between 0.75 and 1.2 Newtons on the tape 17, and
preferably 0.8 to 1 Newton. Such higher than
conventional tension ensures that the head cleaner 10
retains its suitability for use with conventional VCRs.
To accommodate the extra length of tape 17, the
8pool 13 has a larger diameter than conventional cleaner
ca8sette spools. Whereas a conventional spool is about
25mm in diameter, the spool 13 has a diameter greater
than 50mm. Typically, the diameter of the spool 13 is
62mm.
When the PLAY function is stopped, the guide
members 47-52 move towards the cassette housing 11 to
permit the tapes 14, 17 to be rewound on their respective
spools 12, 13. The tape 17 is rewound automatically on
spool 13 by the spring tension 19. The tape 14 is
rewound on spool 12 by the rotation of that spool by its
associated sprocket. When the housing 11 is e~ected from
the VCR the flap 40 is disengaged, and the pawl on the
end of the detente arm 39 engages the toothed edge 38.
By virtue of such engagement, and the tension ln sprlng
19, the ribbons 14, 17 are held ln a retracted positlon
against the front face 16 of the cassette houslng 11.
~he foregoing describes only one embodiment of
the invention, and modifications which are obvious to
those skilled in the art may be made thereto without
departing from the scope of the invention.
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