Method for controlling the feed of an ink ribbon

Abstract: The provision is made of a firmware (F/W: ROM, RAM) which enables an accurate indexing of an ink sheet (2) so that printing is not performed at the joint (3) portion when an ink sheet having a joint (3) is used. Therefore, an ink sheet (2) having a joint can be used, decreasing running cost of the printer.

Description: This invention relates to a method for controlling the feed of an ink ribbon. A description will be first made to a method for manufacturing a conventional ink ribbon in conjunction with Figs. 9 and 10. Fig. 9 is a view illustrating a method for manufacturing a conventional ink ribbon and Fig. 10 is a view illustrating a conventional ink ribbon. In Fig. 9, 1 is a jumbo roll, 2 is an ink ribbon used in a thermo-transfer printer and 3 is a defect portion thereof. One roll of ink ribbon for use in a thermo-transfer printer is prepared by cutting a roll 1 of ink ribbon called a jumbo roll into sections of a predetermined length corresponding to an ink ribbon roll. When a defect is found in the ribbon section as shown in Fig. 9, one complete section corresponding to one roll is discarded or disposed of and another new section corresponding to one roll is cut from the jumbo roll. Fig. 10 illustrates the section corresponding to one roll. In Fig. 10, it is shown that the ink ribbon 2 is attached to bobbins 4 at the opposite ends and yellow ink (Y) is provided with a Y mark 5, magenta ink (M), cyan ink (C) and black ink (B) are provided with M, C and B marks 6, respectively, and an EOI (End Of Ink) mark is provided at the end of the ink ribbon. Reference numeral 8 is a transparent tape. Now the operation of a conventional thermo-transfer printer wall be described in conjunction with Figs. 11 and 12. Fig. 11 is a flow chart showing the operation of the conventional thermo-transfer printer. Fig. 12 is a diagram illustrating a relative relationship between the conventional ink marks and an ink mark sensor of the conventional thermo-transfer printer. In Fig. 11, in a step S1, the ink ribbon 2 is first started to be wound and the judgement whether or not it is the Y mark 5 is made in a step S2. In a step S3, the Y mark 5 is searched for until time-out when it is not the Y mark 5. In a step S4, when the time-out is reached without finding the Y mark 5, it is judged to be a jam error. On the other hand, in a step S5, the index of the ink ribbon is completed when the Y mark 5 is found. In Fig. 12, in a step S10, the ink mark sensor searches for the Y mark 5. In a step S11, a mark edge is detected. In a step S12, the judgement is achieved at the center of the mark as to the M, C or BK mark 6. In a step 13, the Y mark 5 is again searched for. In a step S14, the mark edge is detected. In a step S15, the judgement is achieved at the center of the mark as to the Y mark 5 to complete the search. With the conventional ink ribbon, the roll must not be broken or separated. Therefore, when a defect is generated during the manufacturing of a roll, that roll is entirely wasted. While the yield of the ink ribbon can be increased by removing the portion with a defect and joining a fresh ink ribbon to form a complete roll when the ink ribbon includes a defect, the ink ribbon cannot be precisely joined together at that portion where the ink mark changes because of the simplicity of the joining operation. Therefore, the ink ribbon must be joined by an adhesive tape. However, the conventional thermo-transfer printer cannot use a color ink ribbon with such a join. Accordingly, it is desirable to provide a color printer in which a color ink ribbon with a join can be used. The present invention, therefore, aims to provide a method for controlling the feed of an ink ribbon in a thermo-transfer color printer by which it is possible to also make use of such ink ribbons which comprise some defect portions (as for example part 3 shown in Fig.1a), wherein these defect portions are cut away, the ribbon subsequently being again connected by means of an adhesive tape (see Fig.1c). If such an ink ribbon would be used for a thermo-transfer color printer as it is known from US-A-4 502 057, the formation of correct images would be impossible. It is therefore the object of the present invention to provide a method for controlling the feed of an ink ribbon by means of which correctly formed images are obtainable even then when an ink ribbon having adhesively connected sections is used. This object, according to the present invention, is solved by the advantageous method steps indicated in claim 1. Hence, according to the present invention, after the detection of a yellow color mark, the ink ribbon is fed in a forward direction in order to search an adhesive tape by means of the mark sensor; if, during that search, no adhesive tape could be detected, the ink ribbon is fed in a reverse direction to the position of the previously detected yellow color mark, whereupon the image formation is started as usual; if, however, an adhesive tape could be detected, the ink ribbon is fed in the forward direction until the next yellow color mark is detected. The unusable portion comprising the adhesive tape is therefore skipped and the image formation can be started with the next set of colors. In US-A-4 502 057, there is suggested to provide a thermo-transfer color printer wherein an ink ribbon is used which is comprised of a plurality of succeeding color sets, each color set being comprised of succeeding sections of yellow, magenta, cyan and black color, wherein each color section has a distinct mark which is different from the marks of the other sections and which is arranged such that the begin of each color section can be detected by means of a mark sensor 19, 21. Any hint as to use ribbons being connected by means of an adhesive tape can however not be gathered from that document. In JP-A-59-140086 , there is disclosed a method for accurately detecting a so-called "seam position" of each color part of an ink ribbon. However, a yellow part 11, a magenta part 12 and a cyan part 13 are all continuously seamed in a predetermined order; it follows that the term "seam" used for this known ribbon does not mean anything else than the normal connection between two adjacent color sections. Consequently, the detection of seam positions mentioned in this document corresponds to the detection of the regular ink marks. The present invention will become more readily apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings, in which: Figs. 1a to 1c are views showing the manufacturing method of an ink ribbon suitable for the present invention; Fig. 2 is a block diagram illustrating the color printer of the present invention; Fig. 3 is a side view of the color printer of the present invention; Fig. 4 is a flow chart showing the operation of the color printer of the present invention; Fig. 5 is a diagram showing the relative relationship between the ink mark and the ink mark sensor of the color printer of the present invention; Fig. 6 is a diagram showing the relative relationship between the ink mark and the ink mark sensor of the color printer of the present invention; Fig. 7 is a view illustrating an ink ribbon suitable for use in the color printer of the present invention; Fig. 8 is a view illustrating an ink ribbon suitable for use in the color printer of the present invention; Fig. 9 is a perspective view of the ink ribbon illustrating a method for manufacturing the ink ribbon used in a conventional thermo-transfer printer; Fig. 10 is a view illustrating the ink ribbon used in the conventional thermo-transfer printer and in the color printer of the present invention; Fig. 11 is a flow chart showing the operation of the conventional thermo-transfer printer; and Fig. 12 is a diagram showing the positional relationship between the ink mark and the ink mark sensor of the conventional thermo-transfer printer. At first, a method for manufacturing an ink ribbon suitable for use with a color printer of the embodiment of the present invention will be described with reference to Fig. 1. The ink ribbon corresponding to one roll suitable for use with the color printer of the present invention is prepared by cutting from the jumbo roll 1. However, when there is the defect portion 3 in an intermediate portion, a particular section of the ink ribbon having one set of colors including the defected portion is removed and disposed of. Then, as shown in Figs. 1(b) and 1(c), one portion of the yellow ink section and one portion of the black ink section is connected together by a light-interrupting black adhesive tape 9 to form an ink ribbon 2 corresponding to one roll. When no defect portion 3 is presented in the intermediate portion, the method is identical to the conventional method for manufacturing an ink ribbon. The construction of a color printer of the embodiment of the present invention will now be described in conjunction with Figs. 2 and 3. Fig. 2 is a block diagram illustrating a color printer of the present invention and Fig. 3 is a schematic side view thereof. Throughout the figures, the same reference numerals designate identical or corresponding components. In Fig. 2, reference numeral 10 is an MPU for managing the control of the entire apparatus, 11 is a ROM connected to the MPU 10 through a bus, 12 is a similarly connected RAM, 13 is an ink ribbon motor drive circuit, 14 is an ink ribbon motor connected to the ink ribbon motor drive circuit 13 for taking up and feeding the ink ribbon 2, 15 is an encoder for counting pulses corresponding to the feed amount of the ink ribbon 2, 16 is an ink mark sensor including, for example, five optical sensors arranged widthwise from an end portion of the ink ribbon 2, 17 is a sensor input circuit connected to the encoder 15 and the ink mark sensor 16, 18 is a platen motor drive circuit, 19 is a platen motor connected to the platen motor drive circuit 18, 20 is a clutch control circuit and 21 is a clutch connected to the clutch control circuit 20. In Fig. 3, reference numeral 22 is a platen driven by the platen motor 19, 23 is a thermal head, 24 is a pinch roller, 25 and 26 are feed rollers and 27 is a print paper. It is to be noted that in the present invention the ink ribbon feed control means in the first embodiment is composed of the MPU 10, the ROM 11, the RAM 12, the ink ribbon motor drive circuit 13, the ink ribbon motor 14, the encoder 15, the sensor input circuit 17, etc. Next, the operation of the above-described color printer will now be described with reference to Figs. 4 to 8. Fig. 4 is a flow chart illustrating the operation of the color printer of the present invention. Figs. 5 and 6 are diagrams illustrating the positional relationship between the ink mark and the ink mark sensor. Figs. 7 and 8 are views illustrating the joined ink ribbon which is suitable for use in the color printer of the present invention. In Fig. 4, in a step S20, the MPU 10 starts winding up the ink ribbon 2 by means of the ink ribbon motor drive circuit 13 and the ink ribbon motor 14. In steps S21 ∼ S23, the ink mark sensor 16 searches for the Y mark 5 for a predetermined period of time (time out: corresponding to the time interval between the Y marks) and, when no Y mark is found within the predetermined time period, it is processed as a jam error (for example, a warning lamp on an operation panel is lit). When found, the process proceeds to a step S24. In steps S24 ∼ S26, the joint mark 9 is searched for for a predetermined time period and, when it is not found, the ink ribbon 2 is taken up in the reverse direction. When the mark is found, the process returns to the step S21 to search the next Y mark. In steps S27 ∼ S29, the original Y mark 5 is searched for for a predetermined time period and, when it is not found within the predetermined time period, this is processed as a jam error. When the mark is found, the process proceeds to a step S30. In steps S30 ∼ S33, it is determined whether or not the ink ribbon 2 has been rewound by a predetermined amount (X1) and, when the rewinding has not been completed within the predetermined time, this is processed as a jam error. When the predetermined amount could be rewound the direction of taking up is changed to return to its original direction. In steps S34 ∼ S37, the Y mark 5 is searched for for a predetermined time period and, when not found within the predetermined time period, this is processed as a jam error. When found, the search for the Y mark is completed in a step S37. The searching operation of the joined sections will now be described with reference to Fig. 5. In a step S40, the ink mark sensor 16 searches for the Y mark 5. In a step S41, a mark edge is detected. In a step S42, a determination is made at the center of the mark that it is the Y mark 5. This is made in order to increase the reliability. In a step S43, the join mark 9 is searched for. In a step S44, the mark edge is detected. In a step S45, a determination is made at the center of the mark that it is the join mark 9. In steps S46 ∼ S49, the next Y mark 5 is searched for. The operation for searching the join-less portion will now be described in conjunction with Fig. 6. In a step S50, the ink mark sensor 16 searches for the Y mark 5. In a step S51, the mark edge is detected. In a step S52, a determination is made at the center of the mark that it is the Y mark 5. In a step S53, the join mark 9 is searched for. When the join mark 9 is not found within the time-out range, i.e., within the predetermined section length, the ink ribbon 2 is rewound in the reverse direction in a step S54 and the Y mark 5 is searched for. In a step S55, the mark edge is detected. In a step S56, a determination is made at the center of the mark that it is the Y mark 5. In a step S57, the pulses at the encoder 15 are counted and the ink ribbon 2 is rewound by a predetermined length. In a step S58, the direction of taking up the ink ribbon 2 is returned to its original direction to search for the Y mark 5. In a step S59, the mark edge is detected. In a step S60, a determination is made that it is the Y mark 5, whereby the index of the Y mark 5 is completed. The ink ribbons 2 with the join illustrated in Figs. 7 and 8 are examples of ribbons in which the portion between the EOI mark 7 and the Y mark 5 is filled with a black tape or the like and in which the portion is not filled with the black tape. The ink mark sensor 16, in one example, is composed of five optical sensors arranged from the upper end in Fig. 7. Therefore, the output from the ink mark sensor 16 is expressed, in binary code, "10110" for the Y mark 5, "10000" for the M, C and BK marks, "11111" for the join mark 9 and "10101" for the EOI mark. A binary code in which "1" and "0" is interchanged can be similarly used. In the color printer of the present invention, as previously described, a firmwear (ROM, RAM) enabling accurate indexing of the ink ribbon 2 so that a printing is not performed at the joint portion when the ink ribbon 2 having a join is employed; thus, an ink ribbon with a join can be used, thereby advantageously decreasing the running cost. In manufacturing the ink ribbon suitable for the color printer of the present invention, the join portion of the ink ribbon 2 is connected by means of black tape to facilitate the manufacture, thereby improving the yield of the ink ribbon 2, furtheron, the manufacturing cost can be advantageously decreased.

Claims: Method for controlling the feed of an ink ribbon in a thermo-transfer color printer, said printer comprising a feed control means (10, 13, 14) for feeding said ink ribbon through an image forming means (22, 23) where a color image is formed on a print paper (27), said ink ribbon being comprised of a plurality of succeeding color sets, each color set being comprised of succeeding sections of yellow (Y), magenta (M), cyan (C) and black (BK) color, each color section having a distinct mark (5, 6) being different from the marks of the other sections and arranged such that the begin of each color section is detectable by means of a mark sensor (16) of said color printer, said ink ribbon further comprising sections which are connected by means of an adhesive tape (9) and are therefore not usable for the formation of an image, said method comprising the steps of : [a] feeding said ink ribbon in a forward direction in order to search an adhesive tape (9) by means of said mark sensor (16) after the detection of a yellow color mark (5), [b] feeding said ink ribbon in a reverse direction to the position of said previously detected yellow color mark (5) when no adhesive tape (9) has been detected, and [c] feeding said ink ribbon in the forward direction until the next yellow color mark (5) is detected when an adhesive tape (9) has been detected. Method according to claim 1, characterized in that said step [a] is performed for a predetermined period of time.

Inventors: HIGASHI KAZUHIKO, KOUZAI FUMIO, TAKAKUWA KIYOSHI, HIGASHI, KAZUHIKO, KOUZAI, FUMIO, TAKAKUWA, KIYOSHI, Higashi, Kazuhiko, c/o Mitsubishi Denki K.K., KOUZAI, FUMIO, C/O MITSUBISHI DENKI K.K., TAKAKUWA, KIYOSHI, C/O MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1993
Main classification: B41J35
IPC codes: B41J35, B41J17, B41J2