Title of Invention

A RIBBON CASSETTE FOR THE DOT MATRIX PRINTER OF A COMPUTER

Abstract

A ribbon cassette for the dot matrix printer of a computer, comprising a pre-inked ribbon accommodated in the shell of the cassette, said shell being provided with a removable top cover; a drive gear meshing with a follower gear disposed inside the shell, with the ribbon passing between the gears for enabling the ribbon to be moved along the front face of the cassette, between the print-head and the platen of the printer, characterised in that a recess is provided on the rear face of the cassette and a removable cartridge form s a push-fit in the recess, said cartridge having an ink reservoir and an ink transfer strip in contact with the reservoir, the transfer strip being also in contact with the drive gear whereby ink from the reservoir, permeating through the transfer strip, is continuously transferred to the drive gear, and thence to the ribbon, during movement of the ribbon in the cassette.

Full Text

This invention relates to a ribbon cassette for the dot matrix printer of a computer. The known ribbon cassette for computer printers contains an endless ribbon accommodated inside the cassette and is usually of 136 column or 80 column size depending upon the size of the printer. The ribbon is pre-inked and after sufficient use, the user replaces it by a fresh pre-inked endless ribbon, commonly known as a "refill. Alternatively, the user has a choice of replacing the cassette itself with a new cassette, which is more expensive than replacing the ribbon alone with a refill. There is another smaller form of the known ribbon cassette which has a facility for re-inking the ribbon by means of an ink reservoir which keeps constantly touching the drive gears of the cassette through a transfer medium. However, in this arrangement, the ink reservoir is encapsulated in the cassette and cannot be removed or replaced. Consequently, when the ribbon has been under sufficient use, it has to be replaced by a refill. The ink reservoir now serves no purpose. Alternatively, the cassette itself has to be replaced by a fresh cassette. The life of such known cassettes is poor, calculated in terms of millions of characters. In the known cassettes referred to above, the ribbon is replaced by a refill, by opening the top cover of the cassette, removing the used ribbon, inserting the refill into the cassette and closing the top cover, thereafter. Usually, the typical ribbon cassette of the known kind has the following basic components: Bottom Cover Top Cover Drive Gear Follower Gear Leaf Spring (for imparting the necessary exit tension to the ribbon) Ribbon In heavy printing centers, such as, department stores, banks, hotels and other business establishments, used ribbons have to be frequently replaced with refills, rendering the procedure cumbersome, time consuming and expensive, especially considering the downtime. Several refill packs available in the market, to meet the demand, do not conform to acceptable standards of quality, so much so that the use of such refill packs can result in damage to the printer mechanism or adversely affect the printer performance. This invention therefore proposes a ribbon cassette in which the ribbon will continuously be hiked inside the cassette itself, by means of a removable "plug in" cartridge without requiring replacement of the ribbon with a refill until the ribbon itself is worn out One of the salient advantages of this invention is that, after die cartridge has been used completely, all that is required to be done is to remove the used cartridge and plug in a new cartridge. This procedure hardly takes a few seconds. There is no downtime, no tedious replacement of the ribbon with ft refill and no question of replacement of the cassette itself with a new cassette. Another salient advantage of this invention is that the performance life is much higher than that of the known ribbon cassettes. Various other advantages of this invention will be apparent from its further description given below. The ribbon cassette for a computer printer, according to this invention, comprises a pre-inked ribbon accommodated in the shell of the cassette, said shell being provided with ft removable top cover; & drive gear meshing with a follower gear disposed inside the shell, with the ribbon passing between the gears for enabling the ribbon to be moved along the front face of the cassette, between the print-head and the platen of the printer, characterized in that a recess is provided on the rear face of the cassette and a removable cartridge forms a push-fit in the recess, said cartridge having an ink reservoir and an ink transfer strip in contact with the reservoir, the transfer strip being also in contact with the drive gear whereby ink from the reservoir, permeating through the transfer strip, is continuously transferred to the drive gear, and thence to the ribbon, during movement of the ribbon in the cassette. This invention will now be described in greater detail by referring to the accompanying drawings which illustrate, by way of example, and not by way of limitation, one of possible embodiments of the ribbon cassette proposed herein, Fig. 1 illustrating an exploded view of the ribbon cassette and the cartridge of the embodiment Fig. 2 illustrating an exploded view of the cartridge alone of the embodiment and Fig. 3 illustrating a sectional plan view of the cassette and cartridge assembly of the embodiment. The embodiment illustrated has die following basic components: Bottom portion of the cassette, provided with a recessed rear face Top Cover of the cassette Drive Gear Follower Gear Leaf Spring (for imparting the necessary exit tension to the ribbon) Ribbon Cartridge housing the reservoir felt in a casing Cover for the casing Leaf spring (for imparting the necessary tension to the transfer strip and reservoir felt) A pre-inked ribbon R of a material such as nylon is accommodated in the shell of the cassette. The shell has a removable cover T at its top and is provided with a leaf spring W. A drive gear D and a follower gear F, meshing with each other, are disposed inside the shell. The ribbon passes between the gears and is thus driven along the front face of the cassette between the print-head and the platen of the printer. A recess A is provided on the rear face of the cassette. A removable cartridge C forms a snug push-fit such as a snap fit is the recess. The cartridge has an ink reservoir E accommodated is a casing G. The ink reservoir consists of a pre-inked felt pad H. A transfer strip of felt J is maintained in contact with the reservoir felt H within the casing. The purpose of the reservoir felt H is to hold and deliver the ink to the transfer strip J. In turn, the transfer strip delivers the ink to the drive gear D as the drive gear D tubs against the said strip J. The drive gear in tarn delivers the ink to the ribbon R as it moves between the drive gear and the follower gear F. The reservoir felt that is used is, preferably, the standard SAE F- 10 felt which holds the ink and supplies the same, when required. The transfer strip, which is of higher density than that of the reservoir felt, serves the purpose of controlled delivery of the ink from the reservoir to the drive gear with which the transfer strip is in contact. The transfer strip his two different sides: a rough side which is always in contact with the reservoir felt and through which the ink permeates in a regulated manner to the other side, a soft side, which helps in delivering the ink to the driver gear. Other materia] which has the same or similar characteristics can be used in the place of felt for the ink reservoir as well as for the transfer strip. The cartridge C forms a push-fit into the recess, such as, a snap-fit With such fit the cartridge is removable and replaceable, quickly. The ends of the cartridge are provided with two resilient ribs M and the ends of the recess are provided with mating slots for achieving the snap-fit The sides of the cartridge have two serrated grips K for manually engaging and disengaging the cartridge with respect to the recess. The cover L provided for the casing serves the purpose of enclosing the ink reservoir and a part of the transfer strip, leaving only the other part of the transfer strip exposed for being retained in contact with the drive gear, whenever the cartridge is inserted into the recess. The cover L of the casing is preferably welded to the bottom part N to prevent loss of ink though evaporation or leakage. A leaf spring Q is located within the casing to apply a continuous pressure on the transfer strip such that it always touches the drive gear, whenever the cartridge is snapped on to the cassette. The terms and expressions in this specification are of description and not of limitation, there being no intention to exclude any equivalents of the features illustrated and described, but it is understood that various other embodiments of the ribbon cassette proposed herein are possible without departing from the scope and ambit of mis invention. We Claim: 1. A ribbon cassette for the dot matrix printer of a computer, comprising a pre-inked ribbon accommodated in the shell of the cassette, said shell being provided with a removable top cover; a drive gear meshing with a follower gear disposed inside the shell, with the ribbon passing between the gears for enabling the ribbon to be moved along the front face of the cassette, between the print-head and the platen of the printer, characterised in that a recess is provided on the rear face of the cassette and a removable cartridge forms a push-fit in the recess, said cartridge having an ink reservoir and an ink transfer strip in contact with the reservoir, the transfer strip being also in contact with the drive gear whereby ink from the reservoir, permeating through the transfer strip, is continuously transferred to the drive gear, and thence to the ribbon, during movement of the ribbon in the cassette. 2. A ribbon cassette as claimed in Claim 1 wherein the cartridge forms a snap-fit in the recess. 3. A ribbon cassette as claimed in Claim 1 wherein the ink reservoir consists of material capable of holding and delivering ink to the transfer strip. 4. A ribbon cassette as claimed in Claim 3 wherein the material is felt. 5. A ribbon cassette as claimed in any one of the preceding Claims wherein the transfer strip is made of a material capable of transferring ink from the ink reservoir to the drive gear in a controlled manner. 6. A ribbon cassette as claimed in Claim S wherein the material is felt. 7. A ribbon cassette as claimed in Claim 7 wherein the transfer strip has two different sides, namely, a rough side which is always in contact with the reservoir felt and through which the ink permeates in a regulated manner to the other side, a soft side, which helps in delivering the ink to the driver gear. 8, A ribbon cassette as claimed in any one of the preceding Claims wherein the ends of the cartridge are provided with two resilient ribs and the ends of the recess are provided with mating slots for achieving a snap-fit 9. A ribbon cassette as claimed in any one of the preceding Claims wherein the cartridge has two serrated grips for manually engaging and disengaging the cartridge with respect to the recess. 10.A ribbon cassette as claimed in any one of the preceding Claims wherein the casing is provided with a removable cover for enclosing the ink reservoir along with apart of the transfer strip, leaving only the other part of the transfer strip exposed for being retained in contact with the drive gear. 11. A ribbon cassette as claimed in any one of the preceding Claims wherein a removable leaf spring is located within the casing for ensuring that the transfer strip is always in contact with the drive gear. 12. A ribbon cassette for the dot matrix printer of a computer substantially as herein described and illustrated in the accompanying drawings.

Documents:

0241-mas-2002-abstract.pdf

0241-mas-2002-claims-duplicate.pdf

0241-mas-2002-claims.pdf

0241-mas-2002-correspondence-others.pdf

0241-mas-2002-correspondence-po.pdf

0241-mas-2002-description-(complete)-duplicate.pdf

0241-mas-2002-description-(complete).pdf

0241-mas-2002-drawings.pdf

0241-mas-2002-form-1.pdf

0241-mas-2002-form-19.pdf

0241-mas-2002-form-26.pdf