PRINTING RIBBON CARTRIDGE

Abstract: The present ribbon cartridge (1) contains a continuous web of inked ribbon (2) for a printing machine and includes the printing platen (5) as a part of the cartridge. The com­ bined ribbon cartridge and platen is made of molded plastic and greatly reduces the overall cost of the printer mechan­ ism by eliminating the expensive platen member as a separate element. Longer ribbon life and lower noise levels of operation are also provided by forming the platen mem­ ber in this fashion.

Description: PRINTING RIBBON CARTRIDGE This invention relates to serial or line impact printers and mechanisms in general and specifically to ribbon cartridges and platen elements for use in such machines. Numerous ribbon cartridges are known in the art. These generally fall into two categories. In the first category, ribbon is wound from reel to reel within the cartridge by engagement of one of.' the reels with a power drive source external to the cartridge. Such ribbons are generally caused to traverse a printing area to supply a fresh inked surface between an impact printer and a markable medium such as a sheet of paper positioned over an appropriate platen which is an integral part of the printing machine. A second category of prior art ribbon cartridges are designed to house a continuous loop of ribbon. The ribbon may or may not have a twist in it to create a MOEBIUS loop and is contained within a cassette body; means are provided either within the cassette or in the printing machine for withdrawing the ribbon from the cassette, feeding it past the printing area between a platen and an impact member and returning it to the cassette via a drive means for stuffing it compactly in a random or serpentine fashion within the body of the cassette. Both of the known prior art ribbon cassette categories contemplate an inked ribbon or web or one which is suitably coated with carbon film or the like. Additionally, both categories utilize platens which are an integral part of the printing machine. The ribbon must be drawn from the cassette and exposed to impact between an impact member and a platen during a portion of its journey external to the body of the cassette. Such ribbons or webs are subject to continuous wear when the printer is in use and are often replaced during the life of a printing machine. A typical ribbon may have a useful life of only two to six million character impacts. The printing machines in which they are employed. typically have a finely finished, costly metal bar or resilient carefully formed roller platen or the like which serves as the impact resisting element in the printer for the life thereof. Where wire matrix printers are employed, the platen element is often a metal bar or strip which is carefully machined and must last for the life of the printer. This is a fairly expensive component to manufacture. It also requires that the framewbrk and structure of the pr-inter be very carefully aligned with the impact member or print elements to maintain an even printing character intensity. The expense of this accurate assembly and/or provision for adjustment also adds a considerable portion of cost to the machine. In addition, where hard, wear resistant surfaces are used for the platen material, the repeated impact of the impact member creates a significant noise level which can be objectionable in many circumstances. While resilient surfaces may be applied to the metal platen by a coating of elastomeric material or the like to reduce noise, this material is more subject to wear and leads to a more frequent replacement of the expensive platen element. In light of the foregoing known deficiencies of the prior art ribbon cassettes and platens, it is an object of the present invention to provide an improved replaceable cassette and platen assembly that avoids the difficulties mentioned for designs in which these elements are separate. Yet another object of the present invention is to provide an improved ribbon cassette and platen assembly having reduced noise generation characteristics. The foregoing and still other unenumerated objects of the present invention are met by providing a ribbon cassette in which the platen member is, formed as an integral part thereof. Cassettes are typically made of molded plastic which, according to the durometer of material employed, may be either relatively hard and/or brittle or soft and resilient. Making the cassette of normal injection molded thermoplastic materials is relatively commonplace in the art, but employing such material as a platen integral with the cassette itself represents an improvement. Not only is the high cost of the usual separate platen which is a part of the printing machine eliminated, but the platen need only last as long as the ribbon material instead of for the life of the printing machine. Additionally, since the plastic material is substantially the same resiliency as an elastomeric coated hardened platen, noise reduction is significant. While the platen surfaces may wear out much sooner than a normal platen, it is only required to last for the life of the ribbon and is replaced when the cassette is replaced for the purpose of presenting a fresh ink supply. The platen is thus an integral part and of the same material as the cassette body. Means are provided for guiding the ribbon from an exit point in the cassette body across the surface thereof which is utilized as a platen and back into the cassette in the usual manner. The cassette is modified in design to provide a space between the ribbon and the platen portion of the cassette into which a printing paper may be introduced where front printing is desired. For multiple copy printing or high impact forces, the face of the platen portion may have an integrally molded metal insert which is inserted into the injection mold for the plastic cassette to provide a harder more wear resistant surface to the platen portion of the cassette body. Means for locating the cartridge and platen in accurate registration with the printing element so that the printing line is parallel to the path of the printing element is also provided. Locating holes that cooperate with locating pins fix to the precise location required on the printing machine provide this function. The invention will now be described with reference to a preferred embodiment thereof as depicted in the drawings, in which Figure 1 illustrates a top view of a typical ribbon cassette and platen unit according to the present invention and having its top cover or wall partially broken away to showthe interior. Figure 2 illustrates a cross-sectional view horizontal elevation of the combined cassette and platen depicted in Figure 1. Figure:3 illustrates an enlarged partial section of a modification of the preferred embodiment shown in Figures 1 and 2 and further depicting the locating means for accurate registra tion of the platen surface and the printing machine. Turning to Figure 1, a plan view of a preferred embodiment of the present invention is illustrated. The cassette body 1 is preferably made of injection molded thermoplastic in the conventional manner well known to those of skill in the art. The inked ribbon 2 is illustrated as a continuous or serpentine, randomly stuffed loop which is contained primarily in the body of the cassette 1. Guide arms or fingers 3 extend from the main body portion of the cassette 1 to support the ribbon 2 spaced apart from the platen surface 5 which is a portion of the outer wall of cassette 1. This permits paper to be inserted between the ribbon 2 and the platen surface 5 for printing thereon and maintains alignment between the ribbon 2 and surface 5 in both the horizontal and vertical directions. Guide pin locating holes 4 are also illustrated. These holes cooperate with fixed location guide pins rigidly affixed in a printer mechanism (not shown), to accurately position the platen surface 5 and the cassette 1 relative to the intended printing line for accurate registration with an impact printing means (also not shown). An internally contained drive and pressure roller set 6 are shown in Figure I and will be understood by those of skill in the art to comprise the usual stuffing rollers for drawing ribbon 2 into the body of cassette 1. The ribbon exits from the cassette 1 through an aperture (not shown) near the other end of the cassette. Details of this are well known td those of skill in the art and form no part of the present invention. While the stuffing roller form of cassette embodiment is illustrated, this is not an element of the present invention and it will be understood by those of skill in the art that reel-to-reel cassette ribbons systems may be equally employed. It is the structure of the cassette case and its cooperation with the ribbon and printer with the cassette forming the platen as well that is of importance in this invention. Turning to Figure 2, a horizontal cross-section elevation view taken through the structure depicted in Figure 1 is shown. As may be seen in Figure 2, a cassette body 1 has a hollow interior portion 7 for containing reels or a randomly folded or serpentine stuffed ribbon as depicted in Figure 1. Ribbon 2 is supported on the guide arms or fingers 3 at either end of the cassette as shown in Figure 1 and a small gap or space 9, through which the paper center line 8 passes, is shown. The paper which is to be printed upon is passed between the backside of ribbon 2 and the front surface of the platen 5 and can be impacted by an impacting means driving against the opposite face of the printing ribbon. The center line for the locating pin holes 4 is also shown and it will be understood by those of skill in the art that accurate registration between the front surface of the platen 5 and the center lines of the locating holes 4 will cooperate with precisely located pins within the printing machine to accurately place the platen 5 in a position parallel to the printing line and to the printing head (not shown). As will be instantly appreciated, the platen surface 5 is a directly exposed portion of the wall of the cassette 1 and is formed of the same material, namely injection molded thermoplastic. Such a material is more resilient than hardened or machined steel or similar metal platens normally employed and will therefore experience a greater degree of wear. However, in the present invention, this greater degree of wear of the platen is unimportant since the platen need only last for the life of the ribbon rather than for the life of the printing machine. The resilience of the platen surface greatly reduces the impact noise of printing' which is an additional benefit. Testing has shown that such plastic cassette surfaces function quite well as platens and are.not subject to exceptional wear prior to the time that the ribbon has expired. However, if extremely small dots such as four fine, high resolution matrix printing are required, the impact and penetration forces may be relatively greater and a hardened surface may be applied to the platen 5. This may also be necessary in the case where multiple copies are desired since generally higher print forces are encountered. The plastic cassette, however, still functions to partially reduce noise by resiliently absorbing forces transmitted from the hardened surface. Turning to Figure 3, an enlarged partial view of a modification of the cartridge as depicted in Figure 2 is shown. In Figure 3, the printing elemet 10 is schematically shown as impacting hammer or dot matrix element positioned along the printing center line adjacent to the opposite surface of ribbon 2 from which the platen surface 5 is positioned. Platen surface 5 as depicted in Figure 3 is shown to be a metallic insert 11 which is normally put in place within the injection mold when the plastic 1 is injected to form the cassette body. The metal surface 5 enables the higher printing forces to be withstood and adds no significant cost to the overall cassette. Typically a thin piece of cold rolled sheet steel or the like is sufficient to harden the platen surface for these conditions sufficiently to last the life of a ribbon 2. Also shown are the guide fingers 3 and the aperture 9 through which paper along center line 8 can be inserted. The locating pin apertures 4 with their, center line are also indicated as is the hollow central body cavity 7 for the cassette. . . , The overall action and cooperation of the elements of the present invention may now be clearly understood. The locating holes 4 are accurately and precisely positioned with respect to the platen surface 5 on the surface of the cassette 1 and cooperate with precision locating pins in the printing machine to accurately position the platen surface in registration with the printing line and print elements. The resilient nature of the platen reduces impact printing noise as has been pointed out and, due to its manufacture by injection molding with the cassette, eliminates the cost of an entire separate element in the overall printer structure in the form of a separate platen as is usually employed. The fact that the platen is made of the same thermoplastic material and is formed on a surface of a cassette entails hardly any additional cost whatsoever and is therefore of great benefit in producing an economical and quiet operating printer. The use of cassette surface as the platen element is not limited to the specific embodiment shown since reel-to-reel type ribbon cassettes may be similarly employed. Also, it is not necessary to insert the paper between the ribbon and the platen surface since back printing can be performed with the paper positioned between the impact element and the front surface of the ribbon 2 if desired. In such an operation, as will be readily understood by those of skill in the art, character inversion may occur and hence, the font of the printing element may similarly have to be inverted. If serial dot matrix printing is employed, electronic character reversals are necessary from time to time as appropriate in this type of printing. The registration or locating means in the form of the locating apertures, 4 are positioned in precise relation to the platen surface 5 which is a portion of the surface of the cassette 1. Together they function to create an accurately positioned platen in the printing machine and also serve to accurately position the ribbon with respect to the intended line of printing. Hence, the overall integral structure of ribbon, guide fingers, platen and cassette body is a compact, low cost, quiet operating and easily replaced subassembly for use in a variety of impact printers.

Claims: CLAIMS 1. Printing ribbon cartridge and platen including Åahousing (1) having a generally hollow interior space (4) and a supply of web form marking media (2) contained therein, and entry and exit means in said housing for allowing portions of said media'to enter and exit therefrom, characterized in that it comprises guide means (3) integral with an outer portion of the surface of said cartridge housing to guide a portion of said media across a portion of the exterior surface of said cartridge housing, said portion o exterior surface of said housing adjacent said media (2) and between said guide means (3) comprising an impact resisting platen (5). 2. Ribbon cartridge as described in Claim 1, wherein said guide means (3) comprises projecting wall portions in the form of guide fingers defining the path of said media across the face of said cartridge whereon said platen is located, and extends sufficiently to position the path of said media in a spaced apart relationship from said platen surface to permit paper to be inserted between said media and said platen surface. 3. Print ribbon cartridge including means (1) for storing a supply of pre-inked ribbon (2) or similar marking media in the form of an elongated web, characterized in that it comprises means (3) defining a pathway for at least a portion of said elongated web across an outer surface of said cassette and, coextensive with at least a portion of said path, a printer platen (5) integral with a wall portion of said cartridge. 4. Ribbon cartridge as described in claim 1 or 2 or 3, wherein said platen means has a hard, wear-resistant facing (11) attached thereto.

Inventors: MCADAMS, RONALD PRESTLY, MCCRAY, CHARLES MARTIN
Applicants: INTERNATIONAL BUSINESS MACHINES CORPORATION
Application year: 1982
Main classification: B41J35
IPC codes: B41J11, B41J32