Electrophotography – Internal machine environment – Particle or contaminant control
Reexamination Certificate
2002-03-26
2004-08-10
Chen, Sophia S. (Department: 2852)
Electrophotography
Internal machine environment
Particle or contaminant control
C156S073100, C399S103000
Reexamination Certificate
active
06775493
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a sealing film for toner cartridge ensuring the formation of an opening with a substantially constant width after tearing a central longitudinal portion of said sealing film.
THE PRIOR ART
Up to now many researches have been made in order to find a sealing film for sealing a toner cartridge, which is flexible and which after longitudinal tearing, is suitable for defining an opening with a substantially constant width.
Prestel et al (U.S. Pat. No. 5,110,646) discloses a sealing member not having a preferred tearing direction, which is provided with a series of adjacent perforations. Such perforations cause leakage of toner particles, whereby the use of such sealing member has not be considered as useful by the man skilled in the art.
Films having a preferred tearing linear direction are nowadays used extensively for sealing toner container. However, even with means for lowering the initial tearing force, the opening formed after tearing a central strip is reduced most of the time, some times increased, from the initial tearing end up to the terminal tearing end.
For ensuring a substantially constant width of the opening formed after tearing a central strip from the sealing film, EP-0 788 033 (Canon) has proposed to use a sealing film comprising a base layer having a tearing directionality, a guide layer having a tearing guide portion formed by a laser processing, and a laser barrier layer provided between said base layer and said guide layer. Such a film is expensive and the risk to have an undesired tearing is high as the base layer and barrier layer can induce an undesired tearing.
U.S. Pat. No. 5,523,828 (Canon) discloses a sealing film provided with a flexible tape, a first portion of which attached to the film defines the strip to be torn out, while the other portion of which acts as pulling means. The aim of the first portion of the flexible strip which extends on one surface of the sealing film (i.e. from one free end of the film up to the opposite free end of the film) is to ensure a minimum width of the strip to be torn so as to define an opening or passage for the toner with a minimum width.
Tests made by Applicant have shown that when a film with a tearing directionality is provided with two grooves parallel to the preferred tearing direction, a constant width of the opening formed after tearing the central strip could not be ensured.
It has now been observed that when making cuts or grooves perpendicular to the preferred tearing direction of the film and when tearing the strip in a direction perpendicular to the preferred tearing direction, it was possible to obtain an opening with a substantially constant width.
It has also been observed by Applicant that by selecting the correct material for the sealing member, it was possible to avoid the problem of contamination of the toner with fibrous material.
It has further been observed that when using a too thin film for making an one piece material comprising:
the sealing film provided with cuts or grooves perpendicular to the preferred tearing direction, and
the pulling means,
a risk exists that the pulling means is broken, especially at the place where the pulling means is bent over the sealing film. The present invention has thus for aim to further solve this problem.
SUMMARY OF THE INVENTION
The invention relates to a sealing film for toner cartridge, said film having a longitudinal portion to be torn out between a first end and a second end, said longitudinal portion extending between a first line and a second line and adapted to be torn between a first end and a second end, wherein said sealing film comprises a layer with a thickness comprised between 20 &mgr;m and 1 mm and with at least one preferred substantially linear tearing direction, said layer being provided with at least:
a first longitudinal surface element selected from the group consisting of cuts, grooves, recesses and combinations thereof and extending along the first line, and
a second longitudinal surface element selected from the group consisting of cuts, grooves, recesses and combinations thereof and extending along the second line,
whereby said longitudinal surface elements extend in a direction of at least 5° with respect to the preferred substantially linear tearing direction,
in which the substantially longitudinal portion to be torn out is associated to a pulling means having a portion intended to extend at least partly over one face of the film before the tearing of said portion,
whereby at least the portion of the pulling means adjacent to the first end of the portion to be torn out has a sufficient tearing resistance for preventing a separation between the pulling means and the substantially longitudinal portion to be torn out during at least the tearing of the first end of the substantially longitudinal portion of the film to be torn out.
Advantageously, at least the portion of the pulling means intended to extend at least partly over one face of the film before the tearing of the substantially longitudinal portion of the film has a sufficient tearing resistance for preventing a separation between the pulling means and the first end of the substantially longitudinal portion to be torn out during the tearing of the substantially longitudinal portion of the film to be torn out from its first end up to its second end.
According to an embodiment, the substantially longitudinal portion to be torn out is associated to a pulling means having a portion intended to extend at least partly over one face of the film before the tearing of said portion, whereby at least the portion of the pulling means is intended to be bent before the tearing of the substantially longitudinal portion, so that the pulling means extends at least partly over one face of the film before the tearing of the substantially longitudinal portion of the film. The pulling means has a sufficient tearing resistance for preventing a separation between the pulling means and the first end of the substantially longitudinal portion to be torn out during the tearing of the substantially longitudinal portion of the film to be torn out from its first end up to its second end.
According to a preferred embodiment, the pulling means is made in a material having a sufficient tearing resistance for preventing a rupture of the pulling means during the tearing of the substantially longitudinal portion from its first end up to its second end. Such a pulling means is for example a longitudinally oriented film (for example a film having for example a preferred tearing direction perpendicular to the preferred tearing direction of the sealing film), film comprising a mat of fibres, thicker flexible film, films made in a material having a high tearing resistance, film with a high stretching resistance, semi rigid supports, semi rigid plates or strips, laminated material, etc.
According to a detail of a preferred embodiment, the film and pulling means are made at least partly from one single flexible sheet material with a thickness of at least 40 &mgr;m, preferably of at least 100 &mgr;m, most preferably 125 &mgr;m or more. The film is for example a multilayered film, i.e. comprising at least one layer having a preferred tearing direction and another layer providing tearing resistance, such a non oriented layer, a reinforced layer, etc. In this case, the grooves for defining the first and second lines extend in the thickness of the other layer(s) and partly in the thickness of the layer having a preferred tearing direction.
According to a detail, the longitudinal surface elements (grooves, recesses, etc.) are preferably associated with a means for lowering the initial tearing force.
Preferably, the elements are located on a face of the film intended to be directed towards the toner cartridge. Possibly said elements are located on a face of the film not intended to be directed towards the toner cartridge. According to a possible specific embodiment, the two opposite faces of the film are provided with one or more surface elements.
For example, the
De Kesel Jan
Van Betsbrugge Alexander
CF Technologies
Chen Sophia S.
Darby & Darby
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