AU669220B2 - An improved video head cleaner - Google Patents

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventor: KNOLL SYSTEMS INTERNATIONAL LTD.

DIRK OLBERTZ Address for Service: CULLEN

CO.,

Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Qld. 4000, Australia.

Invention Title: AN IMPROVED VIDEO HEAD CLEANER

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Details of Associated Provisional Application: No. PL5873 filed 16 NOVEMBER 1992 The following statement is a full description of this invention, including the best method of performing it known to us: r i_ 2 THIS INVENTION relates to improved apparatus for cleaning the playing and/or recording 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.

Another example of such VCR head cleaners is i the VH-295 video head cleaner sold in Australia by Kyowa Sonic Co., Ltd.

I However, it has been found that known VCR head i i cleaners are not suitable for all VCRs. In particular, it h1as been found that known VCR head cleaners ar not suitable for some of the new VCRs such as so-called "quick-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 S.a greater extent than its design specifications would 30 normally permit.

SThe operating components of VCRs are very sensitive, and if a spindle or other operating component senses a resistance to rotation greater than a certain level, this will normally activate a shut-off mechanism in the VCR. The use of known cassette cleaners in quickload 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 i ii 3 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 for cleaning a head of a video player/recorder, comprising a cassette housing having a length of cleaning tape mounted therein, the cassette housing being adapted to be inserted in the video player/recorder such that in use the tape is pulled from the housing into contact with the head, characterised in that the tape is resiliently tensioned within the housing and has an effective length of between 220mm and 245mm.

The effective length of the tape is suitably about 233mm.

Typically, the cleaning tape is a chamois q0r 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 a coil spring within the cassette housing, the other end of the coil 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 is 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 cleaning action.

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- L -L I~ "I 3a load machines. This tape length is longer than normal.

4 Whereas the use 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, to have a tension of between 0.75 Newton to 1.2 Newton when fully extended. Typically, the coil spring is selected to provide 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.

The use of a longer cleaning tape renders the cleaning cassette of this invention suitable for use in quick-load or half-load machines, while the use of higher tension in the 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.

,he cleaning tape may suitably be used in "wet" form, i.e. with cleaning fluid applied thereto. A "dry" cleaning tape portion may also be provided for use in conjunction with the "wet" tape.

In order that the invention may be more fully understood and put into practice, a preferred embodiment thereof will now be described by way of example, with e.0: reference to the accompanying drawings in which: Fig. 1 is a diagrammatic plan view of the cleaning cassette of one embodiment of this invention in use, and Fig. 2 is a partial sectional plan view of the cleaning cassette of Fig. 1 when not in use.

As shown in Fig. i, the video head cleaner of one embodiment of this invention comprises a cassette housing 11 having a pair of spools 12, 13 therein.

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 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, 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 peripheral edge 38 which is engaged by a pawl on the end of a pivoted detente arm 39. The spool 12 is thereby prevented from rotating. The detente arm 39 has another arm portion thereof in contact with a pivoted L-shaped flap 40. When the flap 40 is raised, the arm 39 pivots to release the pawl from the toothed edge 38.

There is no need to describe the operation of the VCR in detail as such operation is already well known. However, a brief description of the relevant S 30 operating components of the VCR is given below to assist the understanding of the operation of the head cleaner are typically three magnetic operating 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 video drum with a playing head 32, and an audio head 33.

a, 6 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. i.

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 which fits through the centre of the left spool 12 in a spline fit.

When the cleaning 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 into contact with the heads 31, 32, 33 as shown in Fig.

i. The spool 12 is free to rotate to accommodate the dry S"tape 14 being pulled out of the cassette housing 11. The wet tape 17 however, is pulled out of the housing 11 against the tension of the spring 19. The drive sprocket tell 30 in 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 it will simply rotate against the spring 19 without affecting 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 selfcleaning action.

Ii: j- I- 1 7 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 retains its suitability for use with conventional VCRs.

To accommodate the extra length of tape 17, the spool 13 has a larger diameter than conventional cleaner cassette 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 S' rewound on spool 12 by the rotation of that spool by its associated sprocket. When the housing 11 is ejected from S" S 30 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 in spring 19, the ribbons 14, 17 are held in a retracted position against the front face 16 of the cassette housing 11.

The 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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Claims (9)

1. Apparatus for cleaning a head of a video player/recorder, comprising a cassette housing having a length of cleaning tape mounted therein, the cassette housing being adapted to be inserted in the video player/recorder such that in use the tape is pulled from the housing into contact with the head, characterised in that the tape is resiliently tensioned within the housing and has an effective length [as hereinbefore defined] of between 220mm and 245mm.

2. Apparatus as claimed in claim 1, wherein the effective length of the tape is about 233mm.

3. Apparatus as claimed in claim 1 or 2, wherein the cleaning tape is chamois ribbon having one end secured in a slot in a 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 coil spring being connected to a fixed point in the hoasing.

4. Apparatus as claimed in claim 3, wherein the coil spring is a tension spring having a tension of between 0.75 and 1.2 Newton.

Apparatus as claimed in claim 4, wherein the spring has a tension between 0.8 and 1 Newton.

6. Apparatus as claimed in claim 4 or 5, wherein the tape and/or coil spring pass(es) around a spool Swithin the cassette housing, the spool having a diameter greater than

7. Apparatus as claimed in claim 6, wherein the spool is not rotatably engaged by a drive sprocket in the video player/recorder during use.

8. Apparatus as claimed in claim 3, further comprising a second length of cleaning tape having one end secured in the slot and its other end connected to a second spool in the cassette housing.

9. Apparatus as claimed in claim 8, wherein the cassette housing includes means for securing the second, spool against rotation, said means being disabled when the cassette housing is inserted in a video cassette -v recorder. r 1 i L~ I Apparatus for cleaning a head of a video player/recorder, comprising a cassette housing having a length of cleaning tape mounted therein, the cassette housing being adapted to be inserted in the video player/recorder such that in use the tape is pulled from the housing into contact with the head, characterised in that the tape is resiliently tensioned and its length is greater than 200mm. DATED this tenth day of November 1993 KNOLL SYSTEMS INTERNATIONAL LTD. By their Patent Attorneys Cullen Co. S1 S T- a ~i L ABSTRACT A VCR head cleaning cassette (10) is designed for use with both quick-load (or half-load) VCR machines and conventional VCR machines. The head cleaning cassette (10) comprises a length of cleaning ribbon (17) having one end secured to a slot (15) in the front face (16) of the cassette, and its other end (18) connected to a tensioned coil spring (19) whose other end is secured to a fixed securement (20) within the cassette The resiliently tensioned ribbon (17) has a length greater than 200mm, Lnd preferably between 220mm and 245mm. A second cleaning ribbon (14) has one end secured in the slot (15) and its other end secured to a spool In use, both cleaning ribbons (14, 15) are brought into contact with the playing head (32) of the VCR. I !i py