Patent Publication Number: US-6341906-B2

Title: Cassette containing magnetically affixable printing tape and tape printer which use the cassette

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to cassettes which contain a magnetically affixable printing tape and tape printers which print data on the printing tape. 
     Conventionally, tape printers are widely used which print a character string on a printing tape and which cut a printed portion from the printing tape to produce a label. 
     Tape cassettes used in the printers contain a pair of reels around which a printing tape and an ink ribbon are wound, respectively. The printing tape includes a printing layer of a resin film with an adhesive layer coated on its side and a separable paper strip adhered to the printing layer through the adhesive layer. The tape cassette is set on the tape printer and feeds the printing tape and the ink ribbon to a printing section. 
     The label produced by the tape printer can be pasted on a desired object by separating its separable paper piece therefrom. Once pasted on the object, the label cannot be easily separated from the object because it strongly adheres to the object. 
     A magnet sheet is known, from which a smaller sheet piece of a desire it size is obtained. Appropriate characters are handwritten on the smaller sheet piece, which is then affixed magnetically, for example, to a white board of steel or another magnetic object for use. 
     However, the conventional magnet sheet is not composed in consideration of printing in the tape printer and is not suitable for printing. Thus, tape-like magnet materials are desired from which labels are obtained on the tape printer. The inventors have made a series of studies to put to a practical use magnetically affixable printing tapes on which characters/images are printable by the tape printer. 
     First, in order that the magnetically affixable printing tape may be used in the tape printer like the conventional printing tape with, an adhesive on its side, a magnetically affixable printing tape consisting of a printing layer and a magnetic layer pasted to the printing layer is required to be wound around a reel, and a resulting roll of the printing tape is required to be accommodated within a cassette. Since the printing tape is wound repeatedly around the reel in a superimposing manner, there may occur a trouble, for example, with conveyance of the tape depending on a magnetic pole arrangement pattern formed on the tape, as we have found. For example, a magnet sheet has magnetized lines along which the S and N poles of a particular width alternately arranged extend. A magnetically affixable tape is required to be produced appropriately from the magnet sheet by paying careful attention to the, magnetized lines. Otherwise trouble would occur when a roll of such tape is accommodated within the tape cassette and characters/images are then printed on a tape portion fed out from the cassette. 
     More specifically, when a magnetic tape is magnetized lengthwise or in a direction of its conveyance, S and N poles are alternately formed so as to be arranged widthwise in the tape and to extend lengthwise of the tape. When such magnetized printing tape is wound repeatedly around a reel in superimposing manner, magnetic poles of the same polarity of adjacent turns of the tape can be superimposed. Thus, a repelling force would occur between those poles and hence their adjacent turns of the tape. Thus, one of those adjacent turns would shift widthwise of the tape relative to the other of the tape turns. Since such repelling force is applied perpendicular to the direction of tape conveyance, the tape is likely to meander when it is conveyed to the printing section to thereby hinder appropriate printing. 
     When the printing tape is wound around a holding reel, a magnetic layer of one turn of the tape is brought into contact with a back of a printing layer of the adjacent turn. In this case, small particles or grains of the magnetic layer, which contains a mixture of a synthetic resin or synthetic rubber and magnetic powder, would shift to a surface of the printing tape to soil the same, as we found. A printer of this type generally employs a heat-transfer printing system. When inks of the conventional ink ribbon are not supposed as being toed to pint characters on the printing tape, characters/images printed on the tape would be blurred, which is a new problem. 
     The ink ribbon consists generally of a base film of capacitor paper, glassine or a resin film of polyester or a polyimide resin, and an ink layer coated on the base film. The ink layer includes a mixture of a wax or resin and a coloring agent such as a pigment. When an ink of the ink layer is transferred to the printing medium, a luster occurs on a surface of the ink-transferred to the printing medium, especially in the heat transfer system. In order to suppress this luster, a luster suppressing additive is added into the ink layer or a luster control layer is provided between the base film and the ink layer. 
     In many cases, a pigment added as a coloring agent to the ink layer is, for example, carbon black or an iron oxide in the case of a black ink. Similarly, the luster control layer contains an iron oxide pigment for delustering. 
     We also have found in a test for putting the tape to practical use that the “blurs” of the characters printed on the printing tape are due to exertion of the magnetic drawing force of the magnetic layer on the iron oxide pigment contained in the ink layer/luster control layer. 
     When once a label produced from the magnetic tape is affixed magnetically to a magnetic object, it is difficult to separate the former from, the latter. 
     When the magnetically affixable printing tape contained in the tape cassette is used substantially up to As end, a small end portion of the tape is likely to remain in, be drawn against, the printer and enter a space in the printer and is difficult to remove. 
     In color printing by the tape printer the printing tape is reciprocated so as to assume the same printing start position to thereby perform superimposing print in yellow, magenta and cyan inks. In the conventional tape printer, control of quantities of reciprocation of the tape is provided by sensing with an optical sensor a plurality of marks printed at equal intervals lengthwise on the back of the tape and then counting the sensed number of marks. 
     However, the surface of the magnetic layer generally has a dark color such as brown. In this case, if a plurality of position marks are printed in white at equal intervals such that they can be easily sensed by the optical sensor, they are required to be more or less thick. Thus, irregularities would be produced on the surface of the magnetic layer due to the presence of the marks printed on the surface of the magnetic layer which is brought into contact with the object. Those irregularities would produce gaps between the magnetic layer and the object to thereby reduce the magnetic drawing force of the magnetic layer. 
     SUMMARY OF THE INVENTION 
     It is therefore a first object of the present invention to provide a cassette which contains a magnetically affixable printing tape on which a magnetic pole arrangement pattern is formed to enable the tape printer to approximately print characters/images on the tape without causing trouble, for example, with the tape conveyance. 
     Another object of the present invention is to provide a cassette which contains a magnetically affixable tape in which no parts of the magnetic layer shift to a surface of the printing layer even when the printing layer is wound repeatedly along with the tape around a reel. 
     Still another object of the present invention is to provide a cassette which contains in combination an ink ribbon and a magnetically affixable printing tape by which no blurs occur when characters/images are printed on the tape in a heat transfer system. 
     A further object of the present invention is to provide a cassette which contains a magnetically affixable printing tape including a magnetic layer which provides a label which, even if it is once magnetically affixed to the object, can be easily separated from its object. 
     A still further object of the present invention is to provide a cassette which contains a magnetically affixable printing tape which even when it is used substantially up to its end, no small end portion, of the tape remains within the tape printer and hence no troubles occur. 
     A still further object of the present invention is to provide a tape printer which even when no marks for controlling a quantity of conveyance of a magnetically affixable printing tape are provided on the tape, is capable of controlling the quantity of conveyance of the tape for reciprocating purposes in color printing. 
     In order to achieve the; above objects, the present invention provides a cassette comprising a holding reel around which a magnetically affixable printing tape is wound, the cassette being settable in a tape printer which includes conveying means for conveying the tape of the cassette and printing means for printing characters/images on the tape, 
     the tape comprising a printing layer on which characters/images are printed by the tape printer and a magnetic layer containing magnetic powder magnetized widthwise of the tape and pasted at a side to the printing layer. 
     In a lengthwise magnetized magnetic layer, N and S poles which extend lengthwise the magnetic layer. Thus, when the magnetic tape is wound repeatedly around the reel, a magnetic pole of a polarity of one turn of the tape layer can be superimposed on another pole of the same type of an adjacent turn of the tape layer such that a repelling force occurs between those adjacent poles and those tape turns move widthwise relative to each other. According to the inventive tape, no such repelling force occurs and the tape is appropriately conveyed to the printing section to thereby provide appropriate printing. 
     In the cassette, a side of the magnetic layer pasted to the printing layer preferably has a coated fluororesin layer for preventing small particles or grains of the magnetic layer from moving to the printing layer when the magnetic layer comes into contact with the printing layer due to the magnetic layer and the printing layer being wound around the holding reel. 
     The side of the magnetic layer pasted to the pining layer may comprise a wrinkled one. 
     The ink of the printing ink ribbon accommodated along with the magnetically affixable in the cassette preferably contains a non-magnetic substance ink. By heat-transfer printing characters or images on the tape, using the ink ribbon, no ink transferred to the tape is magnetically drawn, and hence no printed characters/figures are blurred. 
     The magnetic layer has a non-magnetic area formed along at least one edge of the tape. Since a label produced from such magnetically affixable printing tape has the non-magnetized area a, it can be separated at one of those areas even when it is affixed magnetically to a ferromagnet such as steel. 
     The cassette preferably comprises an auxiliary non-magnetic tape provided at a trailing end of the magnetically affixable printing tape and bonded to the holding reel to such a degree that the auxiliary tape is separated, or is not separated, from the holding reel of the tape printer by a conveying force exerted by e convey means as the case maybe. By doing so, even when the tape is substantially used up, leaving its small end portion, which remains within the tape printer, it can be easily taken out because the auxiliary tape is attached to the printing tape end. 
     The present invention also provides a tape printer comprising: 
     a magnetically affixable printing tape comprising a printing layer on which characters/images are to be printed, and a magnetic layer of magnetic powder pasted to the printing layer and magnetized such that N and S poles are alternately arranged longitudinally of the magnetic layer; 
     conveying means for reciprocating the tape a plurality of times along a conveyance path in one and the other directions; 
     printing means for printing characters/images on the tape in a plurality of color inks sequentially in superimposing relationship when the tape is conveyed in the one direction by said conveying means; 
     detecting means for detecting changes of magnetic poles of the tape which passes a predetermined position along the conveyance path when the tape is reciprocated in the conveyance path by said conveying means; and 
     conveyance control means for counting the number of changes of magnetic poles of the tape detected by the detecting means to control a quantity of conveyance of the tape by said conveying means such that a quantity of conveyance of the printing tape in the one direction becomes equal to a quantity of conveyance of the tape in the other direction. 
     According to this tape printer, the changes of magnetic poles of the magnetically affixable tape which passes the predetermined position along the conveyance path is detected by the detecting means in the tape conveyance and the quantity of reciprocation of the tape is controlled based on the number of detected changes of the magnetic poles. Thus, even if there are no conveyance quantity control marks formed on the tape, the quantity of reciprocation of the tape is controlled appropriately. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a tape printer with a cassette which contains a magnetically affixable printing tape as one embodiment of the present invention being shown separated from the printer; 
     FIG. 2 is a plan view of the cassette; 
     FIG. 3 illustrates the tape cassette set in the tape printer; 
     FIG. 4 illustrates the composition of a color ink ribbon contained in the cassette; 
     FIG. 5 is an enlarged cross-sectional view of the magnetically affixable printing tape contained in the tape cassette; 
     FIG. 6 is an enlarged cross-sectional view of another magnetically affixable printing tape contained in the cassette; 
     FIG. 7 schematically illustrates forming wrinkles with rolls on the magnetic tape; 
     FIG. 8 intelligibly illustrates in cross section only three of turns of a magnetically affixable printing tape wound around a reel; 
     FIG. 9 illustrates a principle of occurrence of a trouble in the case of FIG. 8; 
     FIG. 10 illustrates axial shifts of all the respective turns of a tape roll of FIG. 9; 
     FIG. 11 is a perspective view of the cassette; 
     FIG. 12 illustrates the compositions of a magnetically affixable printing tape and especially its magnetic layer according to the present invention accommodated in the cassette of FIG. 11; 
     FIG. 13 illustrates connection of the magnetically affixable printing tape to the reel through an auxiliary tape; 
     FIG. 14 illustrates another magnetically affixable printing tape according to the present invention; 
     FIG. 15 is a plan view of a driving mechanism for the tape printer; 
     FIG. 16 is a side view of the driving mechanism; 
     FIG. 17 is another side view of the driving mechanism; 
     FIG. 18 is a block diagram of an electronic circuit of the tape printer; 
     FIG. 19 shows the composition of a tape position detector coupled to a tape position sensor; and 
     FIG. 20 is a flowchart of a color printing process performed by the tape printer. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will be described next with reference to the accompanying drawings. 
     Referring to FIG. 1, a cassette  24  which contains a magnetically affixable printing tape according to the present invention is shown taken out above a tape printer  10 . As shown in FIG. 1, the tape printer  10  has a key-in unit  12  which includes a plurality of keys  13  to be depressed; that is, character input keys, cursor keys, a form setting key, a print key, a cancel key, function keys, a font magnification key, an enter key  13 , etc., within one half of its housing  11 . 
     A liquid crystal display unit  14  and a tape cassette accommodating section  15  are provided within the other half of the housing  11 . A cover for the tape cassette accommodating section  15  is removed away such that its inside can be seen well. The tape cassette accommodating section  15  contains a swingable thermal head  16  on which a line of heaters (not shown) is arranged; and a platen roller  17  disposed opposite to the thermal head  16 . 
     A guide plate  18 , a tape winding shaft  19 , an ink ribbon winding shaft  21 , and a tape cutter  22  ( 22   a ,  22   b ) are disposed so as to surround the thermal head  16 . A tape discharge exit  23  is formed to the right of the tape cutter  22 . 
     The tape cassette  24  has a cassette case  25  composed of an upper case portion  25   a  and a lower case portion  25   b . The cassette case  25 , contains a holding reel  27  around which a magnetically affixable printing tape  26  is wound repeatedly, a ribbon holding reel  29  around which an ink ribbon  28  of a non-magnetic ink layer is wound repeatedly, and a ribbon winding reel  30  which rewinds a used potion, of the ink ribbon  28 . 
     The tape cassette  24 , tape holding reel  27 , ribbon holding reel  29 . and ribbon winding reel  30  are made of a non-magnetic material such as a synthetic resin. 
     The cassette case  25  has a cut  31  which receives the thermal head  16  to which the printing tape  26  and the ink ribbon  28  are fed from the cassette case  25 . 
     As shown in FIG. 2, the cassette case  25  has a groove  32  for identifying the kind of the cassette. The tape cassette accommodating section  15  has a microswitch (not shown) to get information on the kind of the cassette represented by the groove  32 . 
     FIG. 3 illustrates the tape cassette  24 , which contains the printing tape  26 , set within the tape cassette accommodating section  15 . In FIG. 3, the upper case portion  25   a  is removed away such that the inside of the lower case Portion  25   b  can be seen well. 
     As shown in FIG. 3, when the tape cassette  24  is set in the tape cassette accommodating section  15 , the tape winding shaft  19  is inserted into a hole  27   a  in the holding reel  27  around which the magnetic tape  26  is wound, and the ink ribbon winding shaft  21  is inserted into a hole  30   a  in the ribbon winding reel  30 . 
     As described above, the thermal head  16  is disposed within the cut  31  in the tape cassette  24 . The platen roller  17  is disposed opposite to the thermal head  16  outside the cut  31 . Thus, the tape  26  and ink ribbon  28  are fed in superimposed relationship to between the thermal head  16 , and platen roller  17 . 
     No magnetic metal powder is mixed with the ink and binder in the ink ribbon  28 . Also, in order to prevent a luster from occurring on the ink transferred to the tape, the ink ribbon used in the past generally uses an iron oxide (magnetic substance) pigment. In order to avoid blurs in the print in the present embodiment, a mixture of a non-magnetic coloring agent, an ink and a binder is used without using a magnetic pigment such as iron oxygen. Even when a luster appears more or less on the transferred ink on a magnetically affixable printing tape in the embodiment in the use of the tape, for example, magnetic affixation of the printed label to a white, board of steel, there are no visual problems. It is experienced in a test that the addition of a non-magnetic coloring agent to the ink and binder provides a dear printed image compared to a delustered print. Of course, if necessary, dyes or non-magnetic additives may be added to the ink and binder for delustering purposes, instead of the iron oxide pigment. 
     The ink ribbons contained in the tape cassettes  24  include ones having a base material coated with a black ink for monochromatic printing and a base material coated with yellow, magenta and cyan color inks for color printing. 
     FIG. 4 shows a color pining ink ribbon  28  which has a width corresponding to that of the printing tape  26  and head indicating marks M 1 -M 3  each disposed between the yellow (Y), magenta and cyan (C) inks for indicating the respective heads of the inks. The marks M 1 -M 3  differ in width such that each of them represents two adjacent colors bordering that mark. 
     FIGS. 5 and 6 are enlarged cross-sectional views of different magnetically affixable printing tapes  26   a  and  26   b  each contained in the tape cassette  24 . The printing tape  26   a  of FIG. 5 includes a printing layer  35  and a magnetic layer  36  pasted through an adhesive layer  37  to the printing layer  35 . The printing tape  26   a  of FIG.  5  and the ink ribbon  28  are fed to the printing section of the tape printer  10  such that the printing layer  15  is superimposed on the ink ribbon  28  to thermally print characters/images on the printing layer  35 . The printing layer  35  has a polyester layer  35   b  coated on a film, for example, of a PET resin about 40 μm thick to improve its printability (ink receptivity). 
     The magnetic layer  36  is made of a sheet-like magnetic substance layer  36   a  100-300 μm thick and a fluorine layer  36   b  coated on the layer  36   a . The materials of the magnetic layer  36  include a mixture of a resin such as a polyethylene chloride or a rubbed macromolecule such as natural rubber, neoprene, isopreme, NBR (nitro butadiene rubber) or SBR (styrene butadiene rubber) and ferromagnetic powder, for example, of magnetite, ferrite or a cobalt oxide. 
     The layers  35  and  36  are bonded through an acrylic adhesive layer  37  such that the respective surface layers  35   b  and  36   b  face outward. The half-finished product is then magnetized in a strong magnetic field to complete the magnetically affixable printing tape  26   a.    
     Alternatively, the magnetic layer  36  itself may be cut away from a magnetic substance sheet and then pasted through an acrylic adhesive layer  37  to a back of the resin film  35   a . For example, resin magnetic tapes include composite resin magnet materials which contain as a binding agent a thermoplastic resin such as nylon polypropylene, polyethylene, polyethylene, chloride or vinyl acetate. One of those materials is thermally pressed with a press roller to make uniform thy magnetizing directions of grains of ferromagnetic powder contained in the material perpendicular to a surface of the sheet to thereby form a magnetic tape. The ferromagnetic powder includes Ba or Sr ferrite powder, Alnico magnet (Se-Cr-Co). powder, rare earth cobalt magnet powder and rare earth iron magnet powder, as well known. 
     More specifically, for example, a mixture of a polyamide resin having a melting viscosity of 30-50 Poise at 200° C. and 80-90 weight % of barium ferrite powder and 0.1-1 weight % of zinc stearate or polyethylene wax is kneaded at a temperature of 150-180° C., and then pressed so as to have a thickness of 0.1-0.5 mm. The resulting half-finished product is immediately put in an orienting magnetic field of 10,000 Oersted by a magnetizer, and then cooled to provide a magnet sheet, which has, 700-1600 G(Gauss) as a surface magnetic Ax density, which is usable as the printing tape in the present invention. 
     The magnetically affixable printing tape  26   b  of FIG. 6 is the same in composition as the tape  26   a  of FIG. 5 in that they include PET resin film  35   a , its surface layer  35   b , acrylic adhesive layer  37 , and magnetic substance layer  36   a , excluding a wrinkled surface layer  36   c  formed on the magnetic substance layer  36   a  instead of a coated fluorine layer. 
     As shown in FIG. 7, the preproduced tape  26   c  composed of PET resin film  35   a , its surface layer  35   b , acrylic adhesive layer  37 , and magnetic substance layer  36   a  is passed through a pair of press rollers  38 , one of which (in this example,  38   a ) has a wrinkled surface, and pressed such that a smooth surface  39  of the tape  26   c  is changed to a wrinkled surface  36   c . The tape  26   b , thus obtained, is wound around a holding reel  27  and accommodated in a cassette case  25 , as shown in FIG.  3 . 
     Alternatively, without pressing the preproduced tape  26   c  with the pair of rollers, the tape may be wrinkled in the finishing step subsequent to the pasting step or a magnetic substance sheet (magnetic substance layer  36   a ) only may be previously wrinkled and then pasted to other layers, as shown in FIG.  6 . 
     The wrinkling is not only performed by the above pressing step. For example, a surface of the magnetic substance layer  36   a  may be processed with appropriate chemicals so as to form a coarse surface. 
     The reason why the surface of the magnetic substance layer  36   a  is coated with fluorine or wrinkled, as shown in FIG. 5 or  6 , is to prevent “blocking” which would otherwise occur after the magnetic substance layer  36   a , thus obtained, is wound around the holding reel  27  and then put in the tape cassette  24 , as shown in FIG. 3, as clarified experimentally. 
     The “blocking” implies that as the printing tape  26  is wound around the holding reel  27 , grains of magnetic powder contained in a dispersive manner in the magnetic. substance layer  36   a  are combined with, and shift to, a printing surface (of an improved ink-receptivity surface layer  35   b ) which is wound sequentially along with the magnetic layer  36   a  to be brought into contact with the magnetic substance layer  36   a . Once such blocking occurs, the printing tape surface would be soiled, an appropriate print image could not be formed, and its image quality would be deteriorated. 
     According to the present invention, by coating a surface of the magnetic substance layer  36   a  with fluorine to confine, the magnetic powder, to within the magnetic layer  36   a , as described above, the occurrence of the blocking is prevented with high reliability. 
     Only by forming wrinkles on the surface of the magnetic layer  36   a  instead of coating the same with fluorine, blocking is prevented from occurring, as we formed. It has also been found that irregularities of a surface of the magnetic layer  36   a  due to the wrinkling step are preferably coarser than those of the surface of the improved ink-receptivity surface layer  35   b  as the printing surface to prevent the occurrence of the blocking. 
     When the printing tape is produced, first a magnet sheet (magnetic substance sheet) is produced or a commercially available magnet sheet is gotten and worked so as to provide a tape. The magnet sheet has magnetized lines along which magnetic poles S and N arranged alternately extend. 
     Unless a tape is produced from the magnet sheet by paying appropriate attention to the magnetized lines, the following trouble would occur substantially when a part of the finished magnetically affixable printing tape  26  is wound around the holding reel  27  and then accommodated within the tape cassette  24 . 
     FIG. 8 illustrates in cross section only three taken-out (n-1)th, nth and (n+1)th turns of an experimentally produced magnetically affixable printing tape  40  which is wound: around the holding reel  27 . FIGS. 9 and 10 show a trouble which may occur in this case. As shown in FIG. 10, in this example, the whole tape is magnetized such that the directions of the magnetizing lines on the magnet sheet coincide with the longitudinal line of the printing tape  40 . 
     When the tape  40  is wound around the holding reel  27 , as shown in FIG. 8, the same poles, for example, S or N poles, of the respective turns of the tape are, arranged in overlapping manner. Thus, those poles repel with each other and the respective tape turns shift widthwise as shown in FIG. 9, or widthwise from the reel  27 , as shown by arrows B and C in FIG.  10 . Thus, the tape is difficult to handle and the tape is not fed appropriately to the thermal head  16 . 
     However, this trouble is solved by the present invention which will be described next. FIG. 11 is a perspective view of the tape cassette with its upper case so portion being removed away to illustrate the magnetically affixable printing tape accommodated within the tape cassette. FIG. 12 illustrates the composition of the magnetic layer (magnetic substance layer) of the magnetically affixable printing tape to be accommodated within the tape cassette of FIG.  11 . 
     Since the tape of FIG. 12 is the same in composition as that of FIG. 5, excluding the magnetic substance layer, the corresponding elements of FIGS. 12 and 5 are identified by the same reference numeral. Similarly, since the tape cassette of FIG. 11 is the same in composition as that of FIG. the corresponding elements of FIGS. 11 and 3 are identified by the same reference numeral. 
     As shown in FIG. 11, the tape  26  is magnetized widthwise such that N and S poles are alternately formed lengthwise of the tape on the magnetized surface  41  of the magnetic substance layer  36   a , each pole having a length equal to the tape width and a width of 2 mm. In this case, the magnetizing lines  50  coincide with the direction of the tape width. Thus, when the tape  26  is wound so as to take the form if a pancake, the diameters of turn of the respective wound layers sequentially increase. Thus, the poles of the same polarity of the adjacent turns of the tape seldom overlap, as shown in FIG.  8 . If any, the repelling force is produced longitudinally of the tape or radially of the turns of the, tape and not widthwise of the tape as shown in FIG.  9 . 
     Thus, when the tape  26  which is wound around the holding reel  27  and accommodated within the tape cassette  24  is fed out along with the ink ribbon  28  from the tape cassette  24  as shown in FIG. 11 to the printer section, and characters/images are printed on the tape with the aid of the ink ribbon  28 , the respective turns of the tape in the form of a pancake will not shift axially to thereby take the form of, for example, a cone as shown in, FIG. 10 ,. 
     As shown in FIG. 13, the tape  26  is fixed at an end to one end  42   a  of an auxiliary tape  42  with an adhesive. The auxiliary tape  42  is temporarily fixed at the other end to the holding reel  27  with a weak adhesive agent or tape to such a degree that when the tape  26  is driven by the platen roller  17  in a pressed state between the platen roller  17  and the thermal head  16 , the tape  26  is separated from the auxiliary tape  42 . The auxiliary tape  42  is made of a non-magnetic synthetic resin. Preferably, the length of the auxiliary tape  41  exceeds at least the distance between the thermal head  16  and the cutter  22  or at least the distance between the thermal head  16  and the tape discharge exit  23  such that even when the tape  26  is used substantially up to its end with an end portion of the tape  26  remaining within the printer due to the cutting operation, the tape end portion is easy to take, out from the tape printer because the tape end potion is fixed to the auxiliary tape  42 . 
     Alternatively, the auxiliary tape  42  may be bonded at its other end  42   b  strongly to the tape holding reel  27  to such a degree that the auxiliary tape  42  is not separated from the reel  27  by the tape conveying force applied by the platen roller  17  thereto. In that case, the length of the auxiliary tape  42  preferably exceeds at least the distance between the holding reel  27  and the cutter  22  or at least the distance between the reel  27  and the tape discharge exit  23  in a state where the tape cassette  24  is set within the tape cassette accommodating section  15 . 
     By doing so, finally, since the end portion of the tape  26  can be taken necessarily out of the tape printer in a state is pasted to the auxiliary tape  42 , it does not enter the printing mechanism. 
     Alternatively, only a printing-layer  35  may be provided at the end of the magnetically affixable printing tape  26 , and pasted to the tape holding reel  27  without providing the auxiliary tape  42  and the magnetic layer  36 . 
     FIG. 14 shows a part of a back (magnetized surface) of a magnetically affixable printing tape of another example. In FIG. 14, reference numeral  46  denotes a magnetized area where magnetic poles S and N of a width L are formed alternately longitudinally of the tape, as shown in FIG.  12 . Reference numerals  47   a  and  47   b  each denote a non-magnetized edge. 
     Only the magnetized area of a width L can be formed by a strong magnetic field or by forming a magnetic substance containing polymer material on a portion of the base film having the width L. The non-magnetized area may be provided at one of the side edges  47   a  and  47   b . In either of both the cases, when a magnetically affixable printing tape, for example, affixed magnetically to a white board of steel is to be separated from same, a side edge of the tape is easily picked up by fingers. 
     A driving mechanism of the tape printer of FIGS. 1 and 3 will be described next. FIGS. 15-17 show the driving mechanism for the elements of the tape printer of FIG. 1 and 3. FIG. 15 is a plan view of the driving mechanism, and PIGS.  18  and  17  are each a side view of the driving mechanism. The driving mechanism of FIGS. 15-17 is arranged below the bottom, or in the vicinity of, the tape cassette accommodating section  15  in the FIG. 1 housing A FIGS. 15-17 show the thermal head  16 , platen roller  17 , tape winding shaft  19  and ink ribbon winding shaft  21  of FIG. 1 in order to illustrate the positional relationship between each, of those elements and the driving mechanism. 
     The thermal head  16  and a head arm,  61  compose an L-like member which is pivoted at a point  62  in the vicinity of its corner. The head arm  61  has an elongated slot  63  in which a cam pin (not shown) is slidablly received. The head arm  61  is biased counterclockwise by a tension spring  64  which extends between a free end of the head arm  61  and a housing frame. A tension spring  65  is provided between the vicinity of the corner of the L-like member and the housing frame so as to bias the head arm  61  clockwise. 
     As the cam (not shown) is driven so as to leftward move its pin received slidably in the slot  63 , the head arm  61  and hence the thermal head  16  are turned clockwise around the pivot  62 , and the thermal head  16  is moved to a non-printing position. When the cam is driven so as to rightward move the pin in the slot  63 , the thermal head  16  is turned counterclockwise around the pivot  62  such that the thermal head  16  is pressed at its printing unit (a heater array) provided at its free end against the platen roller  17  through the printing tape  26  and ink ribbon  28 . 
     The tape winding shaft  19  is engaged with a gear  66  which is coupled to a drive system (not shown), and rotated only when the tape is returned back to its print starting position in the color printing operation. The ink ribbon winding shaft  21  is engaged with a gear  67  which is coupled to a drive system (not shown), and rotated. 
     The platen roller  17  includes a platen gear  68  which is engaged with a smaller gear of a speed changing gear unit  69 , which has a larger gear meshing with a drive gear  72  of a tape feed motor  71 . 
     A tape cut driving mechanism is provided, which includes a DC motor  73  which has a drive shaft fixed to a worm  74  which meshes with a worm wheel  75 . A smaller gear integral with the worm wheel  75  meshes with a spur gear  79  integral with a bevel gear  78 , which meshes with another bevel gear  81 . Thus, the rotations of the bevel gear  78  driven by the DC motor  73  in a horizontal plane are converted to those of the bevel gear  81  in a vertical plane. A cutter cam  82  is coaxially coupled to the bevel gear  81 . A micro switch  83  is provided on a printer frame in contact with the periphery of the cutter cam  82 . The micro switch  83  detects the initial position of the cutter cam  82  based on a recess provided at a predetermined position on the periphery of the cutter cam  82  and delivers its detection signal to a controller  90  to be described later. 
     A pin  84  provided on a periphery of the cam  82  to assume its lowest position when the cutter cam  82  is at its initial position is slidably received in a slot  86  in a turning arm  85  integral with a movable blade edge  22   a  of the tape cutter  22  with a free end of the pin  84  which extends through the slot  86  being bent outside the slot  86  such that the pin is not disengaged from the slot  86 . As described above, when the cutter cam  82  is rotated counterclockwise via the worm  74 , worm wheel  75 , smaller gear  76 , reduction gear  77 , spur gear  79 , and bevel gears  78  and  81 , the turning arm  85  of the tape cutter  22  is turned counterclockwise and then, clockwise by the pin  84  in a vertical plane around the pivot  87  to thereby dose/open the movable blade edge  22   a  against/from away the fixed blade edge  22   b  of the tape cutter  22  to cut a tape portion away. 
     Referring to FIG. 18, the controller  90  includes a CPU which is connected to the display unit  14  and the key-in unit  12  shown in FIG.  1 . The CPU is connected to a ROM  91 , a RAM  92 , a counter  93 , an image reader  94 , a cassette groove detector  95 , a tape position sensor  96 , an ink ribbon sensor  97 , a head driver  98 , a step motor driver  99 , a pressing mechanism driver  100  and a DC motor driver  101 . 
     ROM  91  contains programs which control the operation of the tape printer  10 . The controller  90  controls the, operation of the respective elements of the printer based on a program read from ROM  91 . 
     RAM  92  contains an image data area, a print data area, a flag area, a register area, a counter area, a work area, etc., (not shown), which temporarily store predetermined data under control of the controller  90 . 
     The counter  93  sequentially increments is initial set value to generate serial numbers when characters/image are printed. 
     The image reader  94  includes a scanner composed of a CCD (charge coupled device). It reads and outputs an image, for example, of a face photograph for label printing. The cassette groove sensor  102  senses a cassette identification groove  32  formed in the tape cassette  24  which contains the printing tape  26 , and provides a corresponding sensed signal to the cassette groove detector  95 , which receives the sensed signal and delivers it to the controller  90 . 
     Referring to FIG. 19, the tape position detector  96  is connected to a tape position sensor  103  includes a magnetic sensor. The tape position detector  96  includes an AM converter  106  and a binarizing unit  107 . The magnetic sensor  103  is composed of a magnetic resistance element and disposed at predetermined position along the tape conveyance path in the tape printer  10 . 
     The N and S poles are alternately formed lengthwise on the tape  26 . Thus, when the tape  26  passes by the tape position sensor  103 , the strength of the magnetic field applied from the tape  26  to the tape position sensor  103  and hence the resistance value of the magnetic resistance element or tape jot don sensor  103  change. The tape position sensor  103  outputs an analog signal depending on the strength of the magnetic field. This signal is converted by an A/D converter  106  to a digital signal, which is then binarized by the binarizing unit  107  and provided for the controller  90 . The magnetic sensor  103  senses magnetic characteristics of the magnetically affixable printing tape  26  changing as the tape  26  is conveyed. The controller  90  detects a position of the tape  26  in the conveying path by counting the number of changes of the polarities of the magnetic poles of the tape. 
     Returning back to FIG. 18, the ink ribbon detector  97  is connected to the ribbon position sensor  104 , which include an optical sensor. This optical sensor senses a print starting position for each of yellow, magenta and cyan of a color ink ribbon in the full color printing, and outputs a corresponding sensed signal. The ink ribbon detector  97  delivers this signal to the controller  90 . The ribbon Position sensor  104  senses, for example, marks M 1 -M 3  in the example of FIG.  4 . 
     The head driver  98  is connected to the thermal head to heat same under control of the controller  90 . 
     The motor driver  99  drives the tape feed or step motor  71  to thereby drive the platen roller  17 , tape winding shaft  19  and ribbon winding shaft  21  through a gear chain and a clutch mechanism (not shown). 
     The pressing mechanism driver  100  is connected to a head pressing mechanism  105  comprised of a motor or a solenoid. The pressing mechanism driver  100  drives the head pressing mechanism  105  forwardly or backwardly. In printing, it turns and presses the thermal head  16  to and against the platen roller  17 . When the printing tape  26  is fed backwardly to superimpose three prime colors in the full color printing or the printing is terminated, the pressing mechanism driver  100  turns the thermal head  16  away from the platen roller  17 . 
     The DC motor driver  101  drives the DC motor  73  to operate the cutter  22 . 
     Operation of the tape printer  10  in color printing will be described next with respect to FIG. 20 which is a flowchart of a printing process performed by the tape printer. This operation is started by depressing the print key of the key-in unit  12  (step A 1 ). 
     When the printing section prints data stored in the RAM  92  in colors, first, the head of an yellow ink Y contained in the ink ribbon  28  is detected (step A 2 ). More specifically, the ink ribbon winding shaft  21  and the platen roller  17  are rotated by the step motor  71  to convey the ink ribbon  28  and the printing tape  26  together. The ribbon position sensor  104  senses a head indicating mark M 1  of the ink ribbon  28  to thereby terminate this process. In this process, a quantity of conveyance of the magnetically affixable printing tape  26  and the ink ribbon  28  is counted based on the output from the tape position sensor  103 . As described above, when the tape  26  passes by the tape position sensor  103  placed at a fixed position, a signal representing its pole changing appears on the output of the tape position sensor. Thus, a conveyance quantity counter (not shown) provided M 1  the RAM  92  counts the number of times of pole changing. 
     After the head of the Y ink is detected, the thermal head  16  is released from the platen roller  17 , the tape winding shaft  19  is rotated, and only the tape  26  is conveyed backwardly through a distance (step A 3 ) which corresponds to the conveyance quantity counter in the RAM  92  counting down from its present count to zero based on the output signals from the tape position sensor  103 . 
     The thermal head  16  is then pressed against the platen roller  17  through the ink ribbon  28  and the printing tape  26 . In this state, the thermal head driver  98  causes the heaters, of the thermal head  16  to produce heat in accordance with print data stored in the RAM  92  to thereby transfer the Y ink of the ink ribbon  28  thermally to the printing tape  26 . The step motor driver  99  then drives the step motor  71  to rotate the platen roller  17  and the ink ribbon winding shaft  21  to thereby convey the ink ribbon  28  and the tape  26  downstream to the next printing position. In this way, the printing of one line by the thermal head  16  and downward conveyance of the ink ribbon  28  and the printing tape  26  are repeated until an image is printed in the Y ink lengthwise on the tape  26 . The quantity of conveyance of the tape  26  is counted up based on the output from the tape position sensor  103  in this Y ink printing, and stored in the conveyance quantity counter (step A 4 ). $Subsequently to the termination of the image printing in Y ink color, the tape  26  and the ink ribbon  28  are Other conveyed downstream while the head of the magenta ink is being detected. Also in this case, the quantity of conveyance of the tape  26  is counted up based on the output from the tape position sensor  103 , the count, thus obtained, is added to the count produced in the Y ink printing, and the resulting count is then stored in the conveyance quantity counter (step A 5 ). 
     Then, the thermal head  16  is released from the platen roller  17 , the ribbon winding shaft  19  is rotated, and only the printing tape  26  is conveyed backwardly through a distance (step A 6 ) which corresponds to the conveyance quantity counter in the RAM  92  counting down from its present count to zero based on the output signals from the tape position sensor  103 . 
     The thermal head  16  is then pressed against the platen roller  17  through the ink ribbon  28  and the printing tape  26  for one line printing. In this state, the thermal head driver  98  causes the heaters of the thermal head  16  to produce heat in accordance with print data stored in the RAM  92  to thereby transfer the M ink of the ink, ribbon  28  to the printing tape  26 . The step motor driver  99  then drives the step motor  71  to rotate the platen roller  17  and the ink ribbon winding shaft  21  to thereby convey the ink ribbon  28  and the tape  26  downstream to the next one-line printing position. In this way, the printing of one line by the thermal load  16  and downward conveyance of the ink ribbon  28  and the printing tape  26  are repeated such that the M color print data is printed lengthwise in the Y ink printed area on the tape  26  in superimposed relationship (step A 7 ). 
     Subsequently, the head of the cyan C ink is detected (step A 8 ). The tape  26  is backwardly conveyed upstream by the same quantity as the tape  26  was conveyed downstream in the Y and M ink printing processes (step A 9 ). 
     The cyan ink print data is also printed in the same printing area of the tape  26  in superimposing relationship to, the yellow and magenta ink print data in a manner similar to those in which those data were printed (step A 10 ). 
     When the cyan ink print data has been printed in superimposing manner, the step motor driver,  99  drives the step motor  71  to convey the tape  26  to thereby discharge its printed tape potion out of the printer (step A 11 ). The DC motor driver  101  drives the DC motor  73  in this state to actuate the cutter  22  to cut the printed tape portion from the tape  26  (step A 12 ). 
     While in the embodiment the printing tape  26  is, illustrated as having a plurality of N and S poles of a particular width alternately arranged longitudinally of the tape  26 , the N and S poles are not required to be arranged regularly in an alternating manner. A single magnet may be provided instead whose. N or S pole has a strength changing over its length. 
     While in the embodiment the thermal transfer printer which uses a color ink ribbon has been illustrated, the present invention is also applicable to ink jet type color printers. 
     Since the tape printer senses changes in the magnetic characteristic of the printing tape to control the distance through which the printing tape is conveyed, print marks used for control of the conveyance distance may not be provided on the printing tape.