GB2115747A

GB2115747A - Making text which is legible on ink ribbons unrecognisable

Info

Publication number: GB2115747A
Application number: GB08223043A
Authority: GB
Inventors: Heinrich Meinhardt
Original assignee: TA Triumph Adler AG
Current assignee: TA Triumph Adler AG
Priority date: 1982-01-22
Filing date: 1982-08-10
Publication date: 1983-09-14
Also published as: SE8203214L; IT8221010A0; FR2520297A1; JPH0250871B2; JPS58128890A; DE3201924C2; DE3201924A1; GB2115747B; FR2520297B1; SE440465B; IT1151554B; CH655464B

Abstract

In order to make text which is legible on an ink ribbon unrecognisable, the ribbon is mechanically deformed between two rollers 4 and 5 which are biased into engagement with each other. One roller 4 is provided with projections 8 and the other roller 5 has corresponding depressions. As a result, the ink ribbon is deformed as it is moved between the rollers and the impression of the characters is destroyed. <IMAGE>

Description

SPECIFICATION Making text which is legible on ink ribbons unrecognisable This invention relates to making text which is legible on ink ribbons unrecognisable.

It is known that the written text remains clearly legible on ink ribbons which are used only once on typewriters and like printing machines.

The legibility results from the removal of ink particles according to the characters selected during the printing or typing operation and also, even if the remaining ink particles are separated from the ink ribbon because the characters of the type carrier leave behind an impression on the ink ribbon so that the written text also remains clearly legible as a result.

Authorities, notary's offices, solicitors' offices etc., in particular, repeatedly impose the requirement that the possibility of a written text being read by unauthorised persons from the ink ribbon of a typewriter should be avoided. This requirement goes so far that some offices have instructed their staff to take the ribbon cassettes out of the typewriter and to lock them in a safe before leaving the office for example in the evening or over the week-end.

A method and an apparatus, for making the text on typewriter ribbons illegible are disclosed in our co-pending Application No. 8200241. This method is only suitable, however, for ink ribbons which have been completely used. Thus the requirement to make the written text illegible on a ribbon which has been only partially used cannot be met.

The present invention provides a method and an apparatus which renders it possible to make text which is legible on an ink ribbon unrecognisable as close as practicably possible after the impression point in the printing machine so that deciphering is impossible. However, it is to be understood that the invention is not so limited and is applicable to making legible text on ribbons unrecognisable after the ribbon has been completely used.

The invention includes a method of making text which is legible on a used ink ribbon unrecognisable comprising after using the ribbon to print characters, deforming the ink ribbon by mechanical action such that the text which is legible through loss of ink from and/or impression of the characters on the ribbon is made unrecognisable.

As will be appreciated, if further ink particles are detached from the ribbon during the mechanical deformation, the contours of a printed character are destroyed. Again if the impression of the printed characters is made unrecognisable by means of the mechanical deformation, the characters will no longer be decipherable. It is particularly advantageous if the mechanical deformation is effected counter to the direction of typing the characters on the ribbon. The destruction of the printed text is further increased as a result.

The invention also includes an apparatus for making text which is legible on a used ink ribbon unrecognisable, comprising two rollers biased into engagement with each other by biasing means for defining a path between the rollers for the used ribbon, and drive means for driving at least one of the rollers, one of the rollers being provided with projections and the other roller being provided with corresponding projections, whereby, in use, a used ribbon which is conveyed between said rollers is deformed by mechanical action such that text which is legible through the loss of ink from and/or impression of the characters on the ribbon is made unrecognisable.

As will be appreciated while the ink ribbon is being conveyed between the two rollers, the projections press nubs into the ribbon as a result of which the characters are made unrecognisable.

For this purpose, the projections may be wart-like in configuration, and such a configuration is recommended in particular, when the ink ribbon consists of a very thin unstable plastics foil. If the ink ribbon has a certain amount of resilience, however, as a result of a thicker carrier foil and/or a certain material, it is advisable that the projections are spike-like in configuration so that the projections not only deform the ink ribbon but also pierce it inside the deformation whereby a kind of small crater is formed. The "crater hole" eliminates the mechanical stress developing inside the deformation so that the resilience of the crater is largely reduced. As a result, any tendency for the deformation to snap-back is avoided.It will be appreciated that the spacing apart of the projections in the axial and peripheral direction should be kept as small as possible so as to produce as fine a pattern as possible of individual deformations.

In order to be able to insert the ink ribbon conveniently between the rollers, one of them may be mounted on a pivotable lever. The rollers may be disposed in the interior of a ribbon cassette.

Where this is not possible, or wanted, the rollers may be mounted on a carrier for a ribbon cassette.

A similar arrangement can, of course, also be used if the ink ribbon is not inserted in a cassette but on spools in the typewriter, printer or the like. This is usual, in particular, with the type-bar typewriters.

In order that the invention may be better understood, an embodiment thereof, which is given by way of example only, will now be described with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows part of a typed ink ribbon illustrated greatly enlarged; Figure 2 shows a section through the ink ribbon after the legible text thereon has been made unrecognisable; Figure 3 shows a pair of rollers for use in making the legible text on the ribbon unrecognisable; Figure 4 shows a partial view of an alternative roller; Figure 5 shows in simplified form, an arrangement in which the rollers are disposed in a ribbon cassette; and Figure 6 shows an arrangement in which the rollers are disposed in a typewriter beside a ribbon cassette.

In the drawings Figure 1 designates an ink ribbon which comprises in known manner of a plastics foil and a layer of detachable ink particles, which may comprise carbon particles. As can be seen from the illustration, the characters 2 are clearly visible and legible. After the ribbon has been mechanically deformed in a manner to be described hereinafter, the ink ribbon 1 is provided with a large number of small deformations 3, situated closely beside one another, which make it possible to read the characters 2. In addition to the deformation 3 there is also a further partial removal of ink.

Figure 3 shows two rollers 4 and 5 with pivot pins 6 and 7. The roller 4 is provided with projections 8 which are wart-like in construction.

In the example shown, the projections 8 are distributed uniformly over the periphery of the roller 4, in axial rows. The projections 8 of one row are staggered axially in relation to those of an adjacent row. As a result, there is a fine pattern of deformations 3 in the ink ribbon 1.

The roller 5 is provided with depressions 9 in the same pattern as the projections 8 and into which depressions, the ink ribbon 1 is pressed when it is moved along a path between the rollers 4 and 5, which are spring biased into engagement with each other, and at least one of which is driven. The rollers 4 and 5 are mounted for rotation by means of the pivot pins 6 and 7.

The projections 8 may alternatively be spikeshaped in configuration as shown in Figure 4.

During the deformation, the points of the spikeshaped projections penetrate through the plastics foil of the ink ribbon 1 and so eliminate mechanical stresses in the material, as a result of which snapping back of the deformations 3 is avoided.

From the above it is clear that a mechanical action is effected on the ink ribbon 1 by means of the two rollers 4 and 5, in a simple manner, so that the characters 2 can no longer be read. It is immaterial where the rollers 4 and 5 are disposed.

Three possible arrangements are described below.

In the first two arrangements shown in Figures 5 and 6 the rollers act to deform the ribbon downstream of the location at which the characters are printed.

According to Figure 5, the rollers 4 and 5 are mounted for rotation and driving in a ribbon cassette 10. The ink ribbon 1 is unwound from the feed spool 11 and wound on the winding spool 12. Between the arms 13 of the cassette 10, the ink ribbon 1 runs past the impression point A.

After the re-entry into the cassette 10, the ink ribbon 1 is guided between the driven rollers 4 and 5 and in the course of this is deformed by the co-operating projections and depressions as described above.

In the embodiment shown in Figure 6, the rollers 4 and 5 are disposed in the typewriter, printer or similar machine with which the ribbon is being used. In this case, disposed on a carrier 14, which serves as a support for the ribbon cassette 1 5, is a housing 1 6 for the rollers which may appropriately be closed by means of a cover (not illustrated) and which has inlet and outlet slots for the ribbon. The roller 5 is mounted for rotation in the housing 1 6. The roller 4 with the projections 8 is mounted on a lever 1 7 which is pivotally mounted at 1 8 and is subject to the action of a spring 1 9. This tends to press the two rollers 4 and 5 against one another.In the example of embodiment shown, the roller 5 is driven by a belt 20 which receives its drive from the ribbon feed mechanism. In any case, care must be taken to ensure that the drive of the rollers 4 and 5 is effected in synchronism with the drive of the winding spool 21 in the ribbon cassette 15 then in order to prevent unwanted loop formation of the ink ribbon 1 from occurring between the rollers 4 and 5 and the winding spool 21. The inK ribbon runs from the feed spool 22 to the impression point A and then back into the ribbon cassette 1 5.

At the side, the ink ribbon 1 is again conveyed out of the cassette 1 5 and into the housing 1 6. In the course of this it must be taken round guide means 23 and in between the two rollers 4 and 5. For this purpose, the roller 4 can be lifted from the roller 5 against the action of the spring 19. Then the ink ribbon 1 runs back into the ribbon cassette 1 5 so as to be able to be wound up by the winding spool 21.

As usual in typewriters and similar machines, the ink ribbon is moved towards the winding spool 12, 21 by a certain amount on each impression of a character 2. Thus the characters 2 arrive between the rollers 4 and 5 only a short distance after the impression point A and are there made illegible. If necessary, after typing a text to be kept secret, after it is finished, some meaningless characters 2 can be typed so as to convey the text to be protected completely past the rollers 4 and 5. It will be appreciated that the rollers 4 and 5 should be disposed as closely as possible to the impression point A to achieve optimum use of the ink ribbon 1.

The housing 1 6 should be able to be closed as tightly as possible so as to prevent ink particles from falling into the interior of the typewriter for example during the mechanical deformation of the ink ribbon 1 and there causing soiling or even blockages.

A similar apparatus to that described in Figure 6 may also be provided for those typewriters in which the ink ribbon 1 is not inserted in a cassette 10, 1 5 but is wound on loose spools. This is generally the case in type-bar typewriters, and in such typewriters it is envisaged that the rollers 4 and 5 may additionally take over the function of feed rollers for the ink ribbon 1.

It is to be understood that if it were acceptable to have the text contained on the ink ribbon 1 made illegible after the ink ribbon 1 has been completely used up, a third arrangement in which the apparatus for mechanically deforming the ribbon is separate from the typewriter or like printing machine and comprises the rollers 4 and 5 mounted in a housing and provided with a drive motor, is possible.

Claims

1. A method of making text which is legible on a used ink ribbon unrecognisable comprising after using the ribbon to print characters, deforming the ink ribbon by mechanical action such that the text which is legible through loss of ink from and/or impression of the characters on the ribbon is made unrecognisable.

2. A method as claimed in claim 1, wherein the deformation of the ink ribbon is effected counter to the direction of printing the characters.

3. A method as claimed in claim 1 or 2, wherein the deformation is carried out downstream of the location at which the characters are printed.

4. An apparatus for making text which is legible on a used ink ribbon unrecognisable, comprising two rollers biased into engagement with each other by biasing means for defining a path between the rollers for the used ribbon, and drive means for driving at least one of the rollers, one of the rollers being provided with projections and the other roller being provided with corresponding projections, whereby, in use, a used ribbon which is conveyed between said rollers is deformed by mechanical a tion such that text which is legible through the loss of ink from and/or impression of the characters on the ribbon is made unrecognisable.

5. An apparatus as claimed in claim 4, wherein the projections are wart-like in configuration.

6. An apparatus as claimed in claim 4, wherein the projections are spike-like in configuration so as to pierce the ribbon.

7. An apparatus as claimed in claim 4, 5 and 6, wherein one of the rollers is mounted on a pivotable lever which is biased by said biasing means to urge said one roller into engagement with the other roller.

8. An apparatus as claimed in any one of claims 4 to 7, wherein the rollers are disposed in the interior of a ribbon cassette.

9. An apparatus as claimed in any one of claims 4 to 7, wherein the rollers are mounted on a carrier for a ribbon cassette such that the ribbon of a cassette mounted on the carrier can be conveyed between said rollers after the ribbon has been used to print characters, and wherein said drive means are arranged to drive the or each roller in synchronism with a feed mechanism for the ink ribbon.

10. An apparatus as claimed in claim 9, wherein the rollers are disposed in a closable housing provided with inlet and outlet slots for the ribbon.

11. A method of making text which is legible on an ink ribbon unrecognisable, substantially as herein described with reference to the accompanying drawings.

1 2. An apparatus for making text which is legible on an ink ribbon unrecognisable, substantially as herein described with reference to Figures 3 to 6 of the accompanying drawings.