CASSETTE CONTAINING A RECORDING CARRIER IN TAPE FORM

Abstract: Cassette (20) containing a recording carrier (23) in tape form, together with means for transporting the recording carrier along a member forming part of the means for reading and/or writing and/or erasing the recording carrier. The cassette is of hermetically sealed construc­ tion and is filled with a gas which does not react chemically with the surface of the tape or with the surface of the guide means, if the matter exists.

Description: The invention relates to a cassette containing a recording carier in tape form, together with means for transporting the recording carrier along a member forming part of the means for reading and/or writing and/or erasing the recording carrier. A cassette of this kind, particularly one con­ taining an optical recording carrier in tape form, is known from Dutch Preliminary Published Patent Applica­ tion 79.07289. The means for transporting the recording carrier consist in this case of two reels together with a reflector member over which the optical tape is guided during its transport from one reel to the other, in such a manner that the tape is brought into a defined position with respect to a window through which the light beam of an optical read/write head can reach the optical tape. Although the present application relates in par­ ticular to a cassette containing an optical recording carrier in tape form, the problems described below also occur in cassettes containing magnetic recording car­ riers in tape form, such as audio and video cassettes. One problem which occurs in particular in the transporting of the information carrier tape in a cas­ sette is the fact that the tape, viewed on a microscopic scale, does not run at a monotonous speed, but moves in jerks and jumps along the aforesaid window, so that the read or write process is impaired. Another problem is that the tightness of the winding of the tape on the reels varies, so that there is no fixed relationship between the macroscopic posi­ tion of the tape and the position of the reels, even with uniform tractive force on the tape. The invention now seeks to indicate measures by which these disadvantages are eliminated or at least substantially reduced, and by which smooth, uniform transport of the tape can be achieved. This aim is attained with a cassette of the type first defined above in that the cassette is of hermetic­ ally sealed construction and is filled with a gas which does not react chemically with the surface of the tape or with the surface of the guide means, if the latter exists. In particular, a dry non-reactive gas is used. The uneven movement of the band may be due to so-called stick-slip phenomena resulting from chemical reactions on the surface of the tape and/or the surface of the guide member, if the latter exists; these phenomena are effectively avoided by the measures according to the in­ vention. It has been found that as the result of these measures the tape runs considerably more uniformly. It is in particular preferable for the non-reac­ tive gas used to be an inert gas. Good results are ob­ tained with hydrogen gas and helium. It is in addition preferable for the gas in the cassette to be under a low or very low pressure, in other words for a vacuum to be produced in the cassette, in a manner of speaking, and for the residual gas to consist of the non-reactive gas. It has been found that in this way a still further improvement can be achieved in respect of uniform movement of the tape, while the abovementioned problem of uneven tightness of winding on the reels is to a great extent overcome by this means. When gas is present in the cassette, gas inclu­ sions probably occur between the windings on a reel. By forming a vacuum in the cassette, or by bringing the gas in the cassette to a pressure lower than 0.05 MPa, and preferably lower than 0.01 MPa, the influence of these gas inclusions is eliminated. In one form of construction of the cassette the recording carrier tape is provided with a magnetizable recording medium, and the aforesaid member consists of at least one magnetic head mounted in the cassette, while hermetically sealing electric lead-in means con­ nected to the head are disposed in the wall of the cas­ sette. In another embodiment the recording carrier tape is provided with an optical read/write recording medium and the aforesaid member is composed of an optically transparent window in the cassette wall. The invention relates not only to a cassette con­ taining a recording carrier in tape form, but also to a cassette which is intended to contain a recording car­ rier tape and then to be hermetically sealed and filled with a non-reactive gas. The scope of the protection applied for then also extends to the still empty cas­ sette especially intended for this purpose. The drawing shows very schematically a section of a holder containing an optical information carrier in tape form in accordance with the invention. The hol­ der 20 is shown in section, and therefore only the side walls through which the section is taken can be seen in the drawing. It will however be clear that the holder is also provided with top and bottom walls fastened her­ metically sealingly to the closed side wall. In the holder two shafts 26 and 27 are for example fastened to the bottom plate of the cassette. The reels 21 and 22 are mounted for rotation about these shafts. The opti­ cal information carrier tape 23 runs off the reel 21 via a pressure member 24 to the other reel 22. The pressure member 24 is located in front of a translucent window 25 which is provided in the wall of the cassette 20 and is hermetically sealed therein. That part of the optical information carrier tape 23 which is located on the pressure member 24 can be seen through this window by an optical read/write head. The pressure member 24 may be in the form of a rotatably mounted wheel, or else in the form of a non-rotatable sliding member.

Claims: 1. Cassette containing a recording carrier in tape form, together with means for transporting the recording carrier along a member forming part of the means for reading and/or writing and/or erasing the recording car­ rier, characterized in that the cassette is of hermetic­ ally sealed construction and is filled with a gas which does not react chemically with the surface of the tape or with the surface of the guide means, if the matter exists. 2. Cassette according to Claim 1, characterized in that the gas is a dry gas. 3. Cassette according to Claim 1 or 2, characterized in that the gas consists of an inert gas. 4. Cassette according to one of the preceding claims, characterized in that the gas consists of hydro­ gen gas. 5. Cassette according to one of Claims 1 to 3, char­ acterized in that the gas consists of helium. 6" Cassette according to one of the preceding claims, characterized in that the gas present is under a pressure lower than 0.05MPa and preferably lower than 0.01 MPa. 7. Cassette according to one of the preceding claims, characterized in that the recording carrier tape is provided with a magnetizable recording medium, and that the aforesaid member consists of at least one mag­ netic head mounted in the cassette, and that hermetical­ ly sealing electric lead-in means connected to the head are disposed in the wall of the cassette. 8. Cassette according to one of the preceding claims, characterized in that the recording carrier tape is pro­ vided with an optical read/write recording medium and that the aforesaid member consists of an optically transparent window in the cassette wall. 9. Cassette intended to contain a recording carrier in tape form, to be sealed hermetically and to be filled with a non-reactive gas in order to provide a combina­ tion as described in one of the preceding claims.

Inventors: BEAUJEAN, JOSEPH MARIE ELISE
Applicants: DOCDATA N.V.
Application year: 1986
Main classification: G11B23
IPC codes: G11B7, G11B23