Multicolor ink ribbon

Abstract: In the multicolor ink ribbon (10)) in accordance with the present invention, since the middle barrier layer (12) prevents the penetration of inks from the ink layers (11) printing head (1) or printing wires (1b) are not soiled by ink even if various colors are printed repeatedly. Even though they are soiled, the penetration of adhered inks will be prevented from penetrating into the printing surface side of the ribbon (10). Accordingly, in either case, a superb printing performance can be obtained. Also, since the protective layer (13) on the printing head side is protected from impact in printing, the function of the middle barrier layer (12) is not damaged and maintained in good condition for a long time.

Description: The present invention relates to an ink ribbon for multicolor, dot impact printing. In the past, various developments have been made with regard to a multicolor ribbon for a dot impact printer. For example, the invention disclosed in US-A-4526487 is one of them. In this disclosure, an ink ribbon for multicolor, dot impact printing comprises a fabric ink layer. A character or a picture image is formed in color by means of causing a printing head to strike individual colors or combinations of colors on a multicolor ink ribbon, provided with three color stripes of yellow, magenta, and cyan, or four color stripes of yellow, magenta, cyan and black, and which is contained in a cartridge equipped with a means to recirculate the ribbon. However, the prior multicolor ink ribbon employed in a dot impact printer to perform color printing was made of a ribbon of single layer fabric in which three or four colors were impregnated in stripes, and therefore, the tip section of the printing head, or printing wire, was soiled black due to the subtractive color mixture effects of the different inks which adhered to the tip or the wire when those colors were repeatedly printed. This was a problem due to the fact that, when a printing wire struck in that condition the yellow ink stripe, which was a bright color stripe, it badly soiled the yellow ink stripe of the ink ribbon so that the image created by repeated striking of the yellow ink stripe is deteriorated. A solution to this problem is proposed in JP-A-61022979. However, this involves a modified ink ribbon cartridge. It is an object of the present invention to provide an ink ribbon for multicolor printing which can prevent the printing surface from being soiled by contamination on the tip section of the printing head or the printing wire caused by the subtractive color mixture effect, so that a superior image output can be obtained. According to the present invention there is provided an ink ribbon such as disclosed in US-A-4526487, characterized by a protective layer and a barrier layer sandwiched between the protective layer and the ink layer, wherein, during dot impact printing, the barrier layer is impervious to ink from the ink layer and the protective layer protects the barrier layer from physical deterioration. Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross section view of the multicolor ink ribbon in accordance with the present invention; Figure 2 is a plane view of the multicolor printing mechanism which employs a re-inking type ink ribbon cartridge containing the ink ribbons in accordance with the present invention; Figure 3 is a plane view showing the printing state of the multicolor printing mechanism which employs the multicolor ink ribbon in accordance with the present invention; Figure 4 is a front view of a multicolor ink ribbon; and Figure 5 is an oblique exterior view of a re-inking type ink ribbon cartridge showing the second embodiment. Hereinafter, the first preferred embodiment of the present invention is explained in detail, referring to the drawings. Now then, identical symbols are assigned to common components among the respective drawings. Figure 1 is a cross section view of the multicolor ink ribbon in accordance with the present invention. In Figure 1, multicolor ink ribbon 10 in accordance with the present invention is constructed in at least three layers consisting of ink layer 11 on the printing surface side, middle barrier layer 12 which prevents ink penetration, and protective layer 13 which is on the printing head side and protects this middle barrier layer 12. Ink layer 11 consists of, for example, a nylon ribbon produced in a thinner form than prior ink ribbons. In this ribbon 11, four colors of, for example, black, cyan, magenta, and yellow are impregnated in stripes in the same manner as in prior ink ribbons, as is shown in Figure 4. Middle barrier layer 12 is formed of urethane rubber, silicon rubber, nylon, or a film of resin such as polyester, and in some cases, it is formed of a non-porous film obtained by melting the surface of the nylon fabric base of ink ribbon 11. Furthermore, protective layer 13 protects middle barrier layer 12 from the impacts during printing process. The minimum requirement for protective layer 13 is for it to function as a protective layer, and therefore, even a plain ribbon, not coated with any ink, is sufficient, or it is possible to employ a ribbon coated with four color inks in the same manner as ink layer 11 on the printing surface side, or a ribbon coated with a lubricant oil for printing wire 1b of printing head 1. Because of the function of this protective layer 13, printing wire 1b does not damage barrier layer 12 located between ink layer 11 and protective layer 13, as is shown in Figure 3. Thus, barrier layer 12 can maintain a satisfactory condition for a long time without having its function impaired, even though printing wire 1b impacts against the ribbon during printing. Now then, in the event a ribbon coated with four inks is employed as protective layer 13 in the same manner as ink layer 11, the present invention can still display its characteristic function, but its appearance becomes exactly the same as the prior ink ribbon, and in the event a ribbon coated with a lubricant is employed, it becomes possible for this ribbon to contribute to the long term sustenance of the performance of printing head 1. Figure 2 is a plane view of a printing mechanism employing ribbon cartridge 20 of the re-inking type in which is contained multicolor ink ribbon 10 in accordance with the present invention. In ribbon cartridge 20 in accordance with the present invention, the multicolor ink ribbon 10 contained in cartridge case 21 is sandwiched between and fed by two transfer rollers 22. These transfer rollers 22 are supplied with ink by absorbent ink storage 23 through wick 24. The ink led to transfer rollers 22 is transferred to ink layer 11 of the multicolor ink ribbon 10 (refer to Figure 1). As was stated above, multicolor ink ribbon 10 is constructed in multiple layers, wherein barrier layer 12, which prevents ink penetration, is provided between ink layer 11 and protective layer 13. There are two types of for this protective layer 13; a protective layer consisting of an ink ribbon, and a protective layer consisting of material other than the ink ribbon. In the event protective layer 13 is made of an ink ribbon, tip section 1a of printing head 1 or printing wire 1b is contaminated and turns black due to the subtractive color mixture effect, but this contamination is prevented from penetrating to the printing surface side by the presence of middle barrier layer 12, and in the event protective layer 13 consists of a material other than the ink ribbon, tip section 1a of printing head 1 or printing wire 1b is not soiled by the ink, whereby it becomes possible to offer a superb printing performance even if multiple colors are repeatedly printed. Also, in the event ribbon cartridge 20 employs a re-inking system, since the amount of ink consumed by printing is supplied through wick 24 from absorbent ink storage 23 to the printing surface side of ink layer 11 of multicolor ink ribbon 10, the printing density can be maintained so as to be constant during printing, and therefore, even more superb printing performance can be delivered by the synergistic effect between this system and the function of barrier layer 12, which is one of the characteristics of the present invention. According to the first embodiment, since all of the color stripes are formed in a multiple layers, whereby the contamination on the printing head side is prevented from penetrating into the ink layer on the printing surface side by the barrier layer, all characters or picture images to be created by an individual strike or compound strikes can be printed in colors without contamination. Figure 5 is an oblique exterior view of a re-inking type ribbon cartridge showing the second embodiment. Independent ink ribbons 31 to 34 are positioned in tiers in the order of black, cyan, magenta, and yellow from the top in cartridge case 21. Among these ribbons, the ink ribbon which has the multiple layer structure in accordance with the present invention is yellow ink ribbon 34, and the respective ribbons 31 to 33 of black, cyan, and magenta have the same single layer structure as the ribbons based on prior technology. When the ribbon cartridge configured in this manner is used for printing, printing is performed with proper impacts without losing the printing force, since ink ribbons 31 to 33 have a single layer structure. On the other hand, ink ribbon 34 has a multiple layer structure, which is thicker compared to ink ribbons 31 to 33, and has a cushioning effect, softening the force of impact. Therefore, there is a tendency that the yellow color is dimly printed due to the weakened force of impact, but since magenta, cyan, and black are printed with the proper force of impact, they are not dimly printed. Incidentally, since yellow is a light color which is difficult to see when it is independently printed, it is not used alone, and instead, is used to create orange and green by being printed in combination with magenta and cyan, respectively. Since magenta and cyan are not dimly printed, the orange and the green created by printing the combination of yellow and respective two colors are also not dimly printed. In addition, since yellow ink ribbon 34 has a multiple layer structure, the contamination on the tip of the printing head or the printing wire does not penetrate into the ink layer of ink ribbon 34, and therefore, the orange and the green created by combination of these colors do not come out to be contaminated colors. Therefore, the dim printing is effectively eliminated, as a whole, compared to the first embodiment. In the case of the multicolor ribbon in accordance with the present invention, since the middle barrier layer positioned between the ink ribbon and the protective layer does not allow ink penetration, the tip section of the printing head or the printing wire is not going to be soiled by the ink even if multiple colors are repeatedly printed, and even if they happened to be soiled, this contamination is blocked by the middle barrier layer, being unable to reach the printing surface side of the ribbon. Therefore, a superb printing performance can be delivered in either case. Furthermore, since the protective layer on the printing head side protects the middle barrier layer from the impacts during printing, the middle barrier layer can be maintained for a long time without having its function impaired. Incidentally, a case in which the present invention was applied to a multicolor ribbon with four colors was explained in the above mentioned preferred embodiments, but the present invention is not restricted to a ribbon with four colors. It may be embodied in a different system in which ink ribbons of various colors are contained in the same cartridge case in place of a single multicolor ink ribbon and are individually driven. Furthermore, in the preferred embodiment presented above, an explanation was given in the case of a multicolor ribbon having a structure consisting of three layers having different functions. However, each of these functional layers may be produced by means of a plurality of sub-layers. For example, barrier layer 12 or protective layer 13 may comprise two sub-layers so that their functions are further enhanced.

Claims: An ink ribbon for multicolor, dot impact printing comprising a fabric ink layer (11) characterised by a protective layer (13) and a barrier layer (12) sandwiched between the protective layer (13) and the ink layer (11), wherein, during dot impact printing, the barrier layer (12) is impervious to ink from the ink layer (11) and the protective layer (13) protects the barrier layer (13) from physical deterioration. An ink ribbon according to claim 1, wherein the ink layer (11) is impregnated with yellow ink. An ink ribbon according to claim 1, wherein the ink layer (11) is impregenated with a plurality of differently colored inks in longitudinal stripes. An ink ribbon according to claim 1, 2 or 3, wherein the ink layer (11) is made of a nylon fabric and the barrier layer (12) has been formed as a non-porous nylon film by melting said nylon fabric. An ink ribbon cartridge including a plurality of independent ink ribbons according to claim 1 impregnated with different colored ink respectively. An ink ribbon cartridge including an ink ribbon according to claims 2, 3 or 4.

Inventors: MAEKAWA MASANORI OKI ELECTRIC, MIZUTANI MINORU OKI ELECTRIC I, MAEKAWA, MASANORI, OKI ELECTRIC INDUSTRY CO.,LTD., MIZUTANI, MINORU, OKI ELECTRIC INDUSTRY CO.,LTD.
Applicants: OKI ELECTRIC IND CO LTD, OKI ELECTRIC INDUSTRY CO., LTD.
Application year: 1992
Main classification: B41J31
IPC codes: B41J31