COLOR THERMAL PRINTER

Abstract: A color thermal printer of a type which utilizes any one of ink ribbons (15) of different color combination, which comprises a different identifiers (17A, 18A) provided on and peculiar to each of the different ink ribbons (15) and descriptive of the color combination of the respective ink ribbon; and a detecting system cooperable with any one of the identifiers for detecting, and providing an output signal indicative of, one of the ink ribbons of different color combination which is actually mounted on the printer. The output signal from the detecting means is utilized to instruct the thermal printer that the ink ribbon of the particular color combina­ tion has actually been mounted on the printer.

Description: The following generally relates to a color thermal printer of a type which utilizes a color ink ribbon out of a set of ribbons. Each ink ribbon has areas of at least one color. The following additionally relates to such a set of ink ribbons. A typical set of ink ribbons comprises a monochromatic, e. g. black ink ribbon, a three-color ink ribbon comprising e. g. the colors yellow, magenta and cyan, and a four-color ink ribbon comprising e. g. the colors yellow, magenta, cyan, and black. Each ink ribbon is made of a pair of core members and a pigment carrier strip secured with its ends to a respective one of said core members. GB-A-2 110 045 describes a set of two ink ribbons. One of the ink ribbons has a black pigment carrier strip and a wide diameter of the end part of one of said core members (due to a ring mounted there), and the other ink ribbon has a colored pigment carrier strip and the respective core member is provided with a small instead of a large diameter in its end part. The related color thermal printer comprises a detector for detecting the diameter of the end part of said mentioned core member when said two core members are mounted each in one of two mounting means parts. Patents abstract of Japan, Vol. 10, No. 211 (M-501) [2267], July 24, 1986, describes a set of ink ribbons in which the different ribbons differ in their pigment carrier strips and in the depth of a slit provided in the end part of one of the core members. When mounting this core member, a wind-up means has to be introduced into this slit. Afterwards, the position of the wind-up means will depend on the depth of the slit of the ink ribbon just mounted. The related color thermal printer comprises a detector for detecting said position of the wind-up means. In both printers as described above, a detecter having a rather large stroke of its movable part is required. Additionally the position of the movable part has to be detected rather accurately, especially when not only two types of ink ribbons have to be distinguished, but three or even four types. An additional disadvantage in the second mentioned printer is that the wind-up means has to be correctly introduced into the slit. If this is not the case, the detection of the ribbon type will be wrong. Therefore, it was desired to provide a set of ink ribbons for a color thermal printer in which set each ribbon type can be easily and accurately detected. Additionally it was desired to provide a color thermal printer with a simply constructed and easily working ribbon type detector. In the set of ink ribbons according to a first invention, two types of core members are provided and the different ribbons of the set differ not only in different pigment carrier strips but additionally in the combinations of the types of the two core members. E. g. one core member is black and the other is white or both are white or both are black. Such combinations can be distinguished from each other much more simply and accurately than different values of the stroke of the movable part of a mechanical detector. The color thermal printer according to another invention has not only one detecting means as the conventional printer but it has a detecting means part in each of the two mounting means parts to detect the type of core mounted at the respective mounting means part, and it comprises a logic for determining the type ink ribbon from the combinations of signals as received from said two detecting means parts. Due to this construction, this printer can easily and accurately distinguish between a plurality of different ink ribbons. The objects and features mentioned above will readily be understood from the following description taken in conjunction with the preferred embodiment of the inventions with reference to the accompanying drawings in which: Fig. 1 is a block circuit diagram showing a color thermal printer embodying the present invention; Fig. 2 is a schematic perspective view of one of different types of ink ribbons which can be utilized in the practice of the present invention; and Fig. 3 is a block diagram showing the prior art color thermal printer. DETAILED DESCRIPTION OF THE EMBODIMENT Referring first to Fig. 1 which illustrates a color thermal printer embodying the present invention, the thermal printer shown therein comprises R, G and B light sources 1A, 1B and 1C capable of emitting red, green and blue light beams, respectively, towards a document (not shown); a lighting control circuit 2 adapted to control the R, G and B light sources 1A, 1B and 1C so that the light sources 1A, 1B and 1C can be sequentially and cyclically energized in a time sharing manner to emit the red, green and blue light beams; and a CCD image sensor 3 for sensing the R, G and B light beams which have been sequentially and cyclically reflected from the document and for photoelectrically converting the R, G and B light beams into respective R, G and B read-out signals which are sequentially outputted therefrom. The R, G and B read-out signals emerging from the image sensor 3 are, after having been converted into respective digital R, G and B read-out signals by an analog-to-digital converter 5, supplied to a memory unit 4 having R, G and B memory areas 4A, 4B and 4C for the storage of the digital R, G and B read-out signals, respectively. The memory unit 4 is in turn connected with a color converter 6 operable to perform a color conversion so that the R, G and B colors represented by the associated read-out signals can be converted into yellow, magenta and cyan, or respective signals descriptive of yellow, magenta, cyan and black, respectively, depending on the type of ink ribbon actually mounted on the printer as will be described later. The illustrated printer also comprises a central processing unit 7 to which the lighting control circuit 2, the color converter 6, a page memory 8, a thermal printer head drive control circuit 9, a ribbon take-up control circuit 10, a paper feed control circuit 11 and a detector 12 are connected. The detector 12 is in turn connected with first and second sensors 13 and 14 both utilized to identify a particular one of the different types of ink ribbons that is actually mounted on the printer in a manner which will now be described. Referring now to Fig. 2, each of the different types of ink ribbons generally identified by 15 comprises a strip of pigment carrier 16 secured at its opposite ends to first and second, generally elongated core members 17 and 18. Each of these core members has a length greater than the width of the pigment carrier strip 16 so that the opposite ends thereof can protrude axially outwardly from turns of the pigment carrier strip 16 around the respective core member. As shown, at least one end of each of the core members 17 and 18 has a respective identifier 17A or 18A formed or marked thereon. Each identifier 17A or 18A may be in the form of a layer of paint of a particular color, a knurled surface area, or splined grooves, or a combination thereof, which is formed on the peripheral surface of such one end of the respective core member 17 or 18. The identifier 17A and 18A on the respective core members 17 and 18 may be identical with or different from each other. More specifically, as can be understood from the subsequent description, in accordance with the present invention, a combination of identical or different identifiers 17A and 18A is utilized to identify a particular type of ink ribbon 15. For example, assuming that each identifier 17A and 18A is employed in the form of the paint layer, and if the paint layers on the respective first and second core members 17 and 18 represent a combination of white color, the ink ribbon 15 can be identified as the second type II (four-color ribbon); if the paint layers on the first and second core members 17 and 18 represent a combination of black and white color, the ink ribbon 15 can be identified as the first type I (three-color ribbon); and if they represent a combination of black color, the ink ribbon 15 can be identified as the third type III (monochromatic ribbon). This is tabulated below. Ribbon Type Type II Type I Type III Identifier 17A White Black Black Identifier 18A White White Black So far illustrated in Fig. 2, the first core member 17 is shown to have the identifier 17A in the form of the black paint layer and the second core member 18 is shown to have the identified 18A in the form of the white paint layer, signifying that the illustrated ink ribbon 15 is the first type III of ink ribbon. As hereinbefore discussed, the first type I of ink ribbon is a three-color ink ribbon wherein the pigment carrier strip 16 has cyclically alternating ink areas each including three ink layers of yellow, magenta and cyan deposited over the entire length thereof. The second type II of ink ribbon is a four-color ink ribbon wherein the pigment carrier strip 16 has cyclically alternating ink areas each including four ink layers of yellow, magenta, cyan and black deposited over the entire length thereof. The third III type of ink ribbon is a monochromatic ink ribbon wherein the pigment carrier strip 16 has a monochromatic, for example, black, ink layer deposited over the entire length thereof. In each of these types I and II except for the third type III, each ink layer has a surface area corresponding to one-page sheet of the document. Referring to Figs. 1 and 2, the first sensor 13 is positioned in the vicinity of the identifier 17A on the first core member 17 and includes a light emitter 13A for emitting a beam of light towards the identifier 17A and a light sensing element 13B for sensing the beam of light which has been emitted from the light emitter 13A and subsequently reflected back from the identifier 17A. Similarly, the second sensor 14 is positioned in the vicinity of the identifier 18A on the second core member 18 and includes a light emitter 14A for emitting a beam of light towards the identifier 18A and a light sensing element 14B for sensing the beam of light which has been emitted from the light emitter 14A and subsequently reflected back from the identifier 18A. Outputs from the light sensing elements 13B and 14B are applied to the detector 12 by which the type of ink ribbon actually mounted on the printer can be identified in dependence on a combination of the light sensing elements 13B and 14B and, thus, the combination of colors of the identifiers 17A and 18A. An output from the detector 12 descriptive of the particular type of ink ribbon detected as actually mounted on the printer is in turn supplied to the central processing unit 7 which may be employed in the form of a microcomputer. In response to the output from the detector 12, the central processing unit 7, the central processing unit 7 selects one of a number of color printing modes equal in number to the number of the types of ink ribbons available, for example, three color printing modes so far illustrated, under which the printer can be operated. These color printing modes may include a four-color printing mode, a third-color printing mode and a single color printing mode. The central processing unit 7, after having selected one of the color printing modes under which the printer operates, controls the color converter 6, the page memory 8, the head drive control circuit 9, the ribbon take-up control circuit 10 and the paper feed control circuit 11 to make them operate in a manner appropriate to the selected color printing mode so that, in accordance with a known thermal transfer process, ink deposits of different colors in each ink area, or ink deposits of black color, can be transferred from the pigment carrier strip 16 onto a recording paper. More specifically, where the printer is set under the four-color printing mode, Y (yellow), M (magenta), C (cyan) and B (black) data are successively introduced from the color converter 6 into the central processing unit 7 and the page memory 8. The central processing unit 7 when receiving the Y data instructs the ribbon take-up control 10 to drive one of the core members 17 or 18 of the second type II of ink ribbon to bring the yellow ink layer in one of the ink areas in the pigment carrier strip 16 into alignment with an area of the recording paper which has been brought to a predetermined printing position by the paper feed control 11 in response to a command from the central processing unit 7. At the same time, in response to a similar command from the central processing unit 7, a thermal printing head is energized to transfer yellow ink deposits onto that area of the recording paper. Similar operations take place in response to the subsequent M, C and B data sequentially supplied to the central processing unit 7 from the color converter 6 and, consequently, the Y, M, C and B ink deposits are transferred onto the same area of the recording paper in superimposed relationship with each other to give a desired color. When the printer is set under the three-color printing mode, only the Y, M and C data are outputted from the color converter 6 to the central processing unit 7 and, therefore, the printing of black color does not take place. Similarly, when the printer is set under the single color printing mode, only the B data is outputted from the color converter 6 to the central processing unit 7 and, therefore, the superimposed printing of Y, M and C colors does not take place. Thus, in the color thermal printer embodying the present invention, where the second type II of ink ribbon is actually mounted, the first and second sensors 13 and 14 detects the identifiers 17A and 18A on the first and second core members 17 and 18, respectively, and the detector 12 processes the respective outputs from the first and second sensors 13 and 14 to provide an intelligence signal necessary to inform the central processing unit 7 of the use of the second type II of ink ribbon so that the central processing unit 7 can, in response to the intelligence signal, set the printer under the corresponding four-color printing mode. Where the second type II of ink ribbon is replaced with the first type I of ink ribbon, the first and second sensors 13 and 1 4 detects the identifiers 17A and 18A on the first and second core members 17 and 18, respectively, and the detector 12 processes the respective outputs from the first and second sensors 13 and 14 to provide a different intelligence signal necessary to inform the central processing unit 7 of the use of the first type I of ink ribbon so that the central processing unit 7 can, in response to the different intelligence signal, set the printer under the corresponding three-color printing mode. Similarly, where the third type III of ink ribbon is mounted on the printer, a still different intelligence signal is outputted from the detector 12 to the central processing unit 7 whereby the printer can be set under the single color printing mode. Although the present invention has been fully described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. By way of example, while each of the identifiers 17A and 18A has been shown and described as formed on the end of the associated core member 17 or 18, it may be formed on each side marginal area of the pigment carrier strip 16. Again, although each ink layer in each ink area on the pigment carrier strip 16 of any one of the types I to III has been shown and described as having a surface area corresponding to one-page area of the document, it may not be always limited thereto and may be in the form of a band of substantial width extending widthwise of the pigment carrier strip 16. Accordingly, such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

Claims: A set of ink ribbons for a color thermal printer, each ribbon (15) comprising a pair of core members (17, 18) and a pigment carrier strip (16) secured with its ends to a respective one of said core members, whereby the different ribbons of the set differ in the type of the respective pigment carrier strip, and whereby two types of core members (17, 18) are provided within the set of ribbons, characterized in that the different ribbons of the set differ in combinations of the types of their two core members. A set of ink ribbons according to claim 1, characterized in that the two types of core members (17, 18) differ in their colors within at least a restricted area. A set of ink ribbons according to claim 1. characterized in that the two types of core members differ in their surface structure in at least a restricted area. A set of ink ribbons according to one of the claims 2 or 3, characterized in that said restricted area is the area of at least one free end region of each core, said free end region being existent when the length of the core is longer than the width of the pigmented carrier strip. A color thermal printer comprising two mounting means parts for mounting a respective one of the two core members of an ink ribbon (15) out of a set of ink ribbons; and a detecting means (12 - 14) for detecting the mounted type of ribbon to determine the operation mode of the printer in dependence of the type of the ribbon mounted; characterized in that a detecting means part (13, 14) is present at each mounting means part to detect the type of core mounted at the respective mounting means part; and a logic (7) is provided for detecting the type of ribbon from the combinations of signals as received from said two detecting means parts (13, 14). A color thermal printer according to claim 5, characterized in that each detecting means part comprises a light emitter (13A, 14A) and a light sensing element (13B, 14B), the latter one being arranged to receive light emitted from the allocated light emitter and reflected from the respective mounted core.

Inventors: NAGANO, FUMIKAZU, SASAKI, HIROMU
Applicants: SHARP KABUSHIKI KAISHA
Application year: 1988
Main classification: B41J35
IPC codes: B41J2, B41J35