Abstract:
The invention relates to a tape holding case housing a supply of image receiving tape and includes an angled surface to bend the surface of the tape approximately 90°, the angled surface being provided upstream of the printing position of the tape. The tape holding case also includes a casing that is designed to attach the tape holding case to an identically shaped tape holding case.

Description:
This application is a division of application Ser. No. 09/180,502, filed Nov. 12, 1998 now U.S. Pat. No. 6,152,623, which is a 371 of PCT/EP97/05065, filed Sep. 16, 1999. 
    
    
     TECHNICAL FIELD 
     The present invention relates to tape printing apparatus and also to tape holding cases for tape printing apparatus. 
     BACKGROUND ART 
     Known tape printing apparatus of the type with which the present invention is generally concerned are disclosed in EP-A-322918 and EP-A-322919 (Brother Kogyo Kabushiki Kaisha) and EP-A-267890 (Varitronics). These tape printing apparatus each include a cassette receiving bay for receiving a cassette or tape holding case. In EP-A-267890, the tape holding case houses an ink ribbon and a substrate tape, the latter comprising an upper image receiving layer secured to a backing layer by an adhesive. In EP-A-322918 and EP-A-322919, the tape holding case houses an ink ribbon, a transparent image receiving tape and a double-sided adhesive tape which is secured at one of its adhesive coated sides to the image receiving tape after printing and which has a backing layer peelable from its other adhesive coated side. With both these apparatus, the image transfer medium (ink ribbon) and the image receiving tape (substrate) are in the same cassette. 
     The present applicants have developed a different type of tape printing apparatus which is described for example in EP-A-578372, the contents of which are herein incorporated by reference. In this printing apparatus, the substrate tape is similar to that described in EP-A-267890 but is housed in its own tape holding case while the ink ribbon is similarly housed in its own tape holding case. 
     The known tape printing apparatus have input means, for example a keyboard, to allow the user to input an image to be printed. A display is generally also provided to display the input image or messages to the user. A cutting arrangement is provided to separate the image receiving tape on which an image has been printed from the supply of image receiving tape to thereby define a label. 
     In these known tape printing apparatus, the image receiving tape passes in overlap with the ink ribbon through a print zone consisting of a fixed print head and a platen against which the print head can be pressed to cause an image to transfer from the ink ribbon to the image receiving tape. This is usually done by thermal printing where the print head is heated and the heat causes ink from the ink ribbon to be transferred to the image receiving tape. This type of printing is known as thermal transfer printing. Alternatively, the print head may be in direct contact with a thermally sensitive image receiving tape whereby when the print head is heated, an image is printed directly on the image receiving tape. This type of printing is known as direct thermal printing. 
     In EP-A-661163 (Smith Corona), a tape printer is used in combination with a slot-in type cassette. The printhead is privotally fixed to the housing of the tool and interacts with a platen provided in the cassette. Since the printhead is spring biased towards the platen, it is capable of urging the cassette out of the printer, when the latches holding the cassette are released. The motor of this tape printer is located beside the cassette, but in a plane below the cassette, and is connected to the platen provided in the cassette by means of a gear train, parts of which being located below the cassette, as well. 
     EP-A-752321 (Esselte NV) discloses a tape printer in which the motor is located in approximately the same plane as the tape supply, however most parts of the gear train are located below the tape supply. A bevel gear is used for altering the direction of driving torque by 90°. 
     U.S. Pat. No. 5,615,960 (Alps) also discloses a tape printer in which the motor is located beside the tape supply, and most parts of the gear train are located below the tape supply. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a tape printing apparatus having a platen for driving an image receiving tape through a printing zone, and a motor operatively connected to said platen by means of a gear train, wherein said motor and said gear train are approximately located within a plane in which a supply of said image receiving tape accomodated in said tape printing apparatus is arranged, and wherein a pair of gears of said gear train changes the direction of the rotation of the torque driving the platen by 90°, such that the rotational axis of said platen and a driving shaft of said motor include an angle of 90°. 
     It is thus proposed to position the motor and the gear train for driving the platen besides the location in which the tape cassette housing the image receiving tape is accomodated, instead of below the cassette location, as known from the prior art. Thus, a thinner machine can be built. 
     It is proposed that the rotational axis of said platen extends parallel to the plane in which the supply of said image receiving tape accomodated in said tape printing apparatus is arranged. Thus, the case according to this embodiment of the present invention is used in combination with the tape printer according an embodiment of the invention, in which a tape holding case allows due to a 90° bend to have a platen arranged orthogonal with respect to the supply of image receiving tape. This reduces the height required for the driving mechanism of the tape, and a thin tape printer is the advantageous result. 
     There can be provided a tape holding case for use with a tape printing apparatus having a print head for printing an image on an image receiving tape, and a surface, said print head and said surface having a first printing position in which said print head acts against said surface and a second non-printing position in which said print head and said surface are spaced apart, said tape holding case housing a supply of image receiving tape and having an interaction portion for separating the print head and the surface so that the print head and the surface are in the second position during insertion of the tape holding case in the tape printing apparatus, said interaction portion being arranged so that the print head and said surface are in the first position when the tape holding case is received in said tape printing apparatus. 
     By using the tape holding case to separate the print head and the surface, the tape printing apparatus can be simplified in that no mechanism is required to cause the print head to adopt the printing and non-printing positions. The cost of the tape printing apparatus can thereby be reduced. 
     It should be appreciated that in embodiments of the present invention, the surface against which the print head acts may be stationary at all times while the print head moves to cause the first and second positions to be adopted. Alternatively, the print head may be stationary whilst the surface moves to cause the first and second positions to be adopted. It is also possible that both print head and the surface be movable mounted. In the preferred embodiment of the present invention, the surface is substantially stationary while the print head is arranged to move. 
     Preferably, the print head and the surface are normally in the first position and the interaction portion is arranged during insertion to cause the print head and the surface to adopt the second position, said print head and surface being in the first position when the tape holding case is received in said tape printing apparatus. For example, the print head may be biased to the first position so that the interaction portion of the tape holding case acts against the biasing force to move the print head to the second position. 
     Preferably said interaction portion comprises a nose portion or control surface extending generally in the direction of insertion. Thus as the tape holding case is inserted, the interaction portion can cause the print head and the surface to adopt the second position. 
     Preferably said nose portion or control surface has a first surface shaped to gradually move the print head and/or the surface to cause the print head and surface to adopt the second position as the tape holding case is inserted and a second surface shaped to gradually move back the print head and/or the surface to cause the print head and surface to adopt the first position so that when the tape holding case is fully inserted in said tape printing apparatus, said print head and the surface are in the first position. The gradual movement of the print head and/or the surface reduces the possibility of any damage occurring to the print head. 
     Preferably, said first and second surfaces are angled in opposite directions. This permits the print head and/or surface to be eased from the first position to the second position and back to the first position. 
     Preferably a window is provided in said tape holding case adjacent said interaction portion, said image receiving tape being arranged to extend across said window, whereby when the tape holding case is received in said tape printing apparatus, the print head and the surface are in the first position with the print head on one side of the window and the surface against which the print head acts on the other side of the window. 
     Preferably, said print head is mounted on a support member and said interacting portion is arranged to contact said support member during insertion of said tape holding case. By contacting the support member rather than the print head itself, the possibility of damage occurring to the print head can be reduced. 
     Preferably, said interacting portion is arranged to contact said print head support member above and/or below the print head. 
     In one preferred embodiment of the invention, the interaction portion has guide means for guiding said image receiving tape. By using the interaction portion also to provide guide means for the image receiving tape, the risk of tape jamming can be reduced. Tape jamming may occur in conventional tape printing apparatus if the tape gets caught on for example the print head or the platen so that it can not be driven through the tape printing apparatus. This is a problem which may arise during insertion of the cassette in the cassette receiving bay. 
     In one preferred embodiment of the present invention, the guide means is provided by the nose portion. Thus, a single part of the tape holding case provides not only a means by which the print head and the associated surface can be separated but also guide means for the image receiving tape. 
     In some embodiments of the present invention, the tape holding case is provided with reinforcing means for reinforcing the interaction portion. In those embodiments where the interaction portion extends from the main body of the tape holding case, the interaction portion may be relatively weak and susceptible to damage. The reinforcing means reduces the likelihood of damage occurring to the interaction portion. These reinforcing means together with the interaction portion on the main body of the tape holding case may define a recess in which the print head or surface of the tape printing apparatus is receivable. 
     Preferably the tape holding case can be used in combination with a tape printing device. 
     In an embodiment of the invention, there can be provided a tape printing apparatus for printing an image on an image receiving tape and a tape holding case as described above, the tape printing apparatus comprising: 
     receiving means for receiving the tape holding case; 
     a print head for printing an image on said image receiving tape; and 
     a surface against which said print head acts during printing, said print head and said surface having a first printing position in which the print head acts against the surface, wherein when said tape holding case is inserted in said receiving means, said print head and/or said surface are moved by said interaction portion of the tape holding case so that the print head and surface have a second non-printing position in which said surface and said print head are spaced apart and when said tape holding case is received in said receiving means the print head and said surface are in said first position. 
     In an embodiment of the invention, there can be provided a tape printing apparatus for printing an image on image receiving tape, comprising: 
     means for receiving a supply of image receiving tape; 
     a print head for printing an image on said image receiving tape, said print head having a first position in which the print head acts against a surface to print an image on the image receiving tape, a second non-printing position and a third position intermediate said first and second positions; and 
     moving means arranged automatically to move said print head from said third position to said first position when said print head is at the third position. 
     By arranging the moving means automatically to move the print head from the third position to the first position when the print head is at the third position, the need to apply a large external force to cause the print head to adopt the required position is removed. 
     Preferably the moving means comprises biasing means. The biasing means may take the form of a spring. In a preferred embodiment of the present invention, the spring comprises a tension spring which is in a minimum state of tension when in the first and second positions but is in a greater state of tension when in the third position. The increased state of tension of the spring, when in the third position, causes the print head to be moved to the first position. 
     The print head may be mounted on a member, the member having a first portion which co-operates with a supply of image receiving tape as the supply of image receiving tape is inserted in the receiving means, whereby insertion of the supply of image receiving tape causes the print head to move from the second position to the third position. Thus, the insertion of the supply of image receiving tape will cause the print head to be moved from the second to the third position and the moving means will then cause the print head to be moved from the third position to the first position. Thus, embodiments of the invention may permit the displacement which the supply of image receiving tape needs to push the member through to be reduced as compared to other possible arrangements. 
     One advantage of embodiments of the present invention is that the final print head position (i.e. printing position or first position) is unrelated to the final position of the supply of image receiving tape. The final position of the print head should be accurately controlled and generally the number of components which affect it should be minimized. 
     The member may have a second portion arranged below the receiving means, the first portion being supported by said second portion and being in said receiving means. 
     The member may be substantially L-shaped with said print head being mounted on one arm of said L-shape, the first portion of said member being mounted on the other arm of the L-shape and said moving means being coupled to the member. 
     The first portion may have a sloping surface arranged to contact said supply of image receiving tape as it is inserted into the receiving means. Preferably, as the supply of image receiving tape is inserted, the supply of image receiving tape will contact the sloping surface which will gradually move as the supply of image receiving tape is inserted further into the cassette receiving bay. As the first portion moves, so does the part of the member on which the print head is mounted. The first portion may be arranged to push the supply of image receiving tape out of the receiving means as the print head is moved from the first position to the second position. Thus, the supply of image receiving tape may be easily removed from the receiving means, when required. 
     The print head preferably has a fourth position intermediate said first and second positions and the moving means is arranged automatically to move the print head from the fourth position to the second position, when said print head is at said fourth position. The fourth position may be intermediate the third and second positions. 
     Preferably, the moving means comprises an over center mechanism. 
     In an embodiment of the invention, there can be provided a tape printing apparatus for printing on image receiving tape comprising: 
     means for receiving a supply of image receiving tape; 
     a print head for printing an image on said image receiving tape; 
     a surface against which said print head co-operates to print an image on said receiving tape, said surface having a first position in which said surface acts against the print head and a second position in which the said surface is spaced apart from said print head, said surface further having a third position intermediate said first and second positions; and 
     moving means arranged automatically to move said surface from said third to said first position when said surface is at the third position. 
     In an embodiment of the invention, there is provided a tape holding case housing a supply of image receiving tape, wherein a bend of approximately 90° is provided in the tape upstream the printing position of said tape. 
     The tape holding case according to this embodiment offers several advantages. First of all, the printed image receiving tape emerges from the case in plane in which the printed image can be easily seen by the user, since this plane extends (due to the 90° bend) parallel to the plane defined by the case and the supply of image receiving tape within the case. Since the latter is generally located parallel to the keyboard and the display of the tape printer, the emerging printed tape can be easily seen and checked by the user regarding typing errors. The second advantage is associated with the sixth aspect of the present invention: 
     In an embodiment of the invention, there is provided a tape holding case housing a supply of image receiving tape, the tape holding case comprising a casing having means thereon for attaching the tape holding case to a second tape holding case. The proposed tape holding case is thus easily stackable. 
     In an embodiment of the invention, there can further be provided a tape printer in combination with a tape holding case with means for attaching it to a second tape holding case, wherein the tape printer has a zone for receiving the tape holding case, wherein the zone comprises elements interacting with the means of the tape holding case for attaching it to a second tape holding case. 
     Thus, the means for attaching the tape holding case to a second one can further serve to guide and hold the tape holding case in the respective tape printer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a better understanding of the present invention and as to how the same may be carried into effect, reference will now be made by way of example to the accompanying drawings in which: 
     FIG. 1 shows a plan view showing the front of a tape printing apparatus; 
     FIGS. 2 a  to  2   c  show a schematic plan view of a first cassette receiving bay with a first cassette, FIGS. 2 a  to  2   c  showing the three stages during the insertion of the cassette in the cassette receiving bay; 
     FIG. 3 shows a perspective view of the cassette shown in FIGS. 2 a  to  c;    
     FIG. 4 shows a cross-sectional view of part of the cassette shown in FIG. 3 along line A—A; 
     FIG. 5 shows a view from above of a portion of a third cassette receiving bay with no cassette present; 
     FIG. 6 is a cross-sectional view of part of the print head arm of FIG. 5 along line VIII—VIII; 
     FIG. 7 shows a modified version of the cassette of FIG. 3; 
     FIG. 8 shows an enlarged view of the nose portion of the cassette of FIG. 7; 
     FIG. 9 is a simplified block diagram of control circuitry for controlling the tape printing apparatus; 
     FIG. 10 is a view showing a second tape printing apparatus; 
     FIG. 11 shows a top view of a cassette for use in the tape printing apparatus of FIG. 10; 
     FIG. 12 is a side view of the cassette of FIG. 11; 
     FIG. 13 is a perspective view of the cassette of FIG. 11; 
     FIGS. 14 a  to  14   e  show a schematic plan view of the cassette receiving slot of the apparatus of FIG. 10 with the cassette of FIG. 11, FIGS. 14 a  to  14   e  showing five stages during the insertion of the cassette in the cassette receiving slot; 
     FIG. 15 is a view showing the interior of the apparatus of FIG. 10; 
     FIG. 16 is a side view on the apparatus of FIG. 15; 
     FIG. 17 is a schematic plan view of a fifth cassette receiving bay in which a fifth cassette is inserted; and 
     FIG. 18 is a schematic plan view of a sixth cassette receiving bay with a sixth cassette inserted therein. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a plan view of a tape printing apparatus  2 . The tape printing apparatus  2  comprises a keyboard  4 . The keyboard  4  has a plurality of data entry keys such as numbered, lettered and punctuation keys  6  for inputting data to be printed as a label and function keys  8  for editing the input data. The keyboard  4  may also have a print key  10  which is operated when it is desired that a label be printed. Additionally, an on/off key  12  is also provided for switching the tape printing apparatus on and off. 
     The tape printing apparatus  2  has a liquid crystal display (LCD)  14  which displays the data as it is entered. The display  14  allows the user to view all or part of the label to be printed which facilitates the editing of the label prior to its printing. Additionally, the display  14  is driven by a display driver  16  which can be seen in FIG.  9 . 
     Next to the keyboard  4  of the tape printing apparatus  2 , there is a cassette receiving bay  18  which is arranged to receive a cassette  20  housing a supply of image receiving tape  24 . The cassette receiving bay  18  is generally covered by a cassette bay lid  40 . Various embodiments of the cassette receiving bay  18  and the cassettes to be received therein will now be described in relation to FIGS. 2 to  16 . 
     A first embodiment of the present invention will now be described with reference to FIGS. 2 a  to  c ,  3  and  4 . These Figures show the key elements present in the cassette receiving bay  218 . In this embodiment, a print head  222  is mounted on a print head arm  226  which is pivotable about pivot point  228 . The pivot point  228  is arranged at one end of the print head arm  226  while the print head  222  is arranged at the other end thereof. The print head  222  acts against a rotatable platen  234  which is provided in the tape printing apparatus  2 . The print head  222  is biased in a direction towards the platen  234 . The platen  234  rotates in the direction of arrow F to drive the image receiving tape  24  through the tape printing apparatus  202  as an image is printed thereon. 
     In addition to a supply spool  232  of image receiving tape  24 , the cassette  220  includes a nose portion  240  which extends outwardly from the main body  243  of the cassette  220 . The cassette  220  is inserted into the cassette receiving bay  218  in the direction of arrow G, with the nose portion  240  forwardmost. 
     The nose portion  240  will now be described with reference to FIGS. 2 a  to  c  as well as FIGS. 3 and 4. The nose portion  240  comprises a wall  242  extending parallel to the plane of the image receiving tape  24 . This wall  242  is effectively a continuation of one of the walls  245  of the main body  243  of the cassette  220 . A window  244  is defined in this wall  242 . The window  244  is positioned such that when the cassette  220  is in the position shown in FIG. 2 c , that is fully received in the cassette receiving bay  218 , the platen  234  is on one side the window  244  and the print head  222  is on the other side thereof. The window is also sufficiently large so that the print head  222  can be biased against the platen  234  through the window  244  so that an image is printed on the image receiving tape  224  and the image receiving tape  224  is also driven through the tape printing apparatus. 
     Also provided on the wall  242  of the nose portion  240 , which can be seen particularly clearly from FIGS. 2 a  to  2   c  is a bulged portion  246 . The bulged portion  246  is provided directly adjacent the window  244  on the side of the window further from the spool  232  of image receiving tape  24 . The bulged portion  246  extends outwardly from the plane of the wall  242  both on the side of the wall  242  adjacent the print head  222  and the opposite side of the wall  242 . The purpose of this bulged portion  246  is to move the print head  222  away from the platen  234  when the cassette is first inserted (see FIGS. 2 a  and  2   b ) and subsequently to allow the print head  222  to contact platen  234  when the cassette is fully inserted as shown in FIG. 2 c.    
     On the side of the bulged portion  246  adjacent the print head  222 , two sloping sides  248  and  250  are provided. The two sloping sides  248  and  250  slope outwardly in a direction away from the print head  222  from a common point  232 . When the cassette  220  is first inserted in the cassette receiving bay  218  in the direction of arrow G, the print head  222  comes into contact with the first sloped surface  248  which slopes in a direction toward the print head  222  to point  232 . As the cassette  220  continues to be pushed into the cassette receiving bay  218 , the print head  222  is urged by the sloping surface  248  to pivot in a direction away from the platen  234 , about pivot point  228 . As the cassette  230  continues to be inserted, the print head  22  moves into contact with sloping surface  250 , which slopes from point  232  in a direction towards the platen  234 . Finally, when the cassette  220  is fully received in the cassette receiving bay  218  as shown in FIG. 2 c , the print head  222  is over the window  244  and contacts the image receiving tape  24  which extends there across. The print head  222  then acts against the platen  234  such that an image can be printed on the image receiving tape  24  and the image receiving tape  24  is driven through the tape printing apparatus. The reverse process occurs when the cassette  220  is removed from the cassette receiving bay  218  so that the print head  222  is moved out of contact with the platen  234  whilst the cassette  220  is being removed from the cassette receiving bay. 
     It should be appreciated that the bulged portion  246  will generally be arranged to contact the print arm  226  on which the print head is supported rather than the print head  222  itself to thereby avoid damaging the print head  222 . Thus, the bulged portion  246  contacts the print head arm  226  at a location above and/or below the print head  222 . The bulged portion  246  may therefore have a U-shaped cross-section such as shown schematically in FIG.  4 . As can be seen in this embodiment, the two arms  252  and  254  of the U-shaped cross-section contact the print head arm  226  above and below the print head  222 . 
     Reference will now be made to FIGS. 7 and 8 which show a second embodiment, which is a modification of the embodiment shown in FIGS. 2 a  to  c ,  3  and  4 . In the embodiment shown in FIGS. 7 and 8, the cassette  260  has a nose portion  262 . For clarity, the bulged portion has been omitted from the arrangement shown in FIGS. 7 and 8. However, the embodiment shown in FIGS. 7 and 8 would incorporate the bulged portion discussed in relation to the previous embodiment. The nose portion  262  has, as can be clearly seen from FIG. 8, a boxed-shape cross-section  264  which encloses the image receiving tape  265 . As with the embodiment shown in FIGS. 2 to  4 , the nose  262  is provided with a window  266  which permits the print head to act against the platen while an image is being printed on the image receiving tape. The box section  264  has the advantage that the risk of tape jams is considerably reduced. 
     The cassette  260  shown in FIG. 7 has two triangular portions  268  and  270  extending between the nose portion  262  and the main body  272  of the cassette  260 . The triangular regions  268  and  270  are coplanar with the bottom surface of the cassette  260  and the top surface of the cassette  260  respectively. These triangular web portions  268  and  270  reinforce the nose portion to increase the resistance to damage of the nose portion  262 . The print head may be received in the enclosed space defined by the two triangular web portions  268  and  270  along with an inner wall portion of the nose portion  262  and the wall  274  of the cassette body  260 . Alternatively, the arrangement may be such that a platen could be accommodated in that recess. The web portions  268  and  270  may be of any suitable material such as plastics. The embodiment shown in FIGS. 7 and 8, may be modified so that no bulged portion is provided on the nose portion  262 . The nose portion  262  on its own may be sufficient to move apart the print head and the platen against which the print head cooperates. However, it is preferred that the bulged portion be present. This has the advantage that the nose portion does not contact the print head itself avoiding the possibility that the print head might be damaged. 
     Reference will now be made to FIG. 5 which shows a third embodiment of the present invention. In FIG. 5, the position of the print head arm  326 , when closed is shown in solid lines while the position of the print head arm  326  when in the open position is shown in dotted lines. The print head arm  326  comprises a first portion  327  and a second portion  328 . The print head arm portions  327  and  328  together define an L-shaped print head arm  326 . The print head arm  326  is pivotable about pivot point  330  which is arranged at a corner region  331  of the L-shaped print head arm  326 . The second print head arm portion  328  carries the print head  322  itself. The print head is arranged to cooperate with a rotatable platen  334 . 
     A print head spring  336  is attached at one end to a spring anchor point  338  and at the other end to an attachment point  340  on the print head arm  326 . The spring  336  is an extension spring which is arranged to be held under tension. It should be appreciated that the first portion  327  of the print head arm  326  will in use be arranged below the floor of the cassette receiving bay. A wedge  342  is arranged on the first portion  327  of the print head arm  326 . This wedge  342  is arranged to extend above the floor of the cassette receiving bay and is shown in more detail in FIG.  6 . 
     When the cassette receiving bay is empty, the print head arm  326  is in the position shown in dotted lines in FIG. 5. A cassette is arranged to be inserted into the cassette receiving bay in the downward direction, that is in a direction towards the plane of the page containing FIG.  5 . As the cassette is inserted, it engages the wedge, which can be seen in FIG.  6 . As the cassette is moved downwardly, the bottom edge of the cassette engages the wedge  342  at location  343  gradually moving the wedge and hence the first portion  327  of the print head arm  326  in the direction of arrow H. As the print head arm  326  is pivotably movable about pivot point  330 , the second portion  328  of the print head arm  326  moves in the direction of arrow I towards the rotatable platen  334 . As the second part  328  of the print head arm  326  moves towards the rotatable platen  334 , the length of the spring  336  extends slightly until it reaches a maximum length when the print head arm  326  is in a position halfway between those two positions illustrated in FIG.  5 . Once the print head arm has passed this halfway point, the tension in the spring  336  urges the spring to the position shown in solid lines in FIG. 5 so that the print head  322  is in contact with the rotatable platen  334 . 
     In order to remove the cassette, the user moves the print head arm  326  from the position shown in solid lines in FIG. 5 to the position shown in dotted lines. As the print head arm  326  moves towards the position shown in dotted lines, the wedge portion  324  acts against the cassette to push it up out of the cassette receiving bay. The print head arm  326  may be operated by turning a lever or pressing a button. 
     Thus, the print head  322  is mounted on a print head arm  326  on which the cassette acts on, via the wedge  342 , as the cassette is inserted. The spring  336  is arranged to pull the print head  322  into the printing position in which the print head  322  acts against the platen once cassette insertion has caused the print head to move a relatively short distance from the open position (shown in dotted lines). This has the advantage that the cassette itself does not have to oppose the print head force. 
     Reference will now be made to FIG. 9 which generally shows a simplified block diagram of control circuitry which can be used with any of the described embodiments. A drive roller  30  (see FIGS. 15 and 16) and/or the rotatable platen  234  are driven by the motor  42  so that it rotates to drive the image receiving tape  24  in a direction which is parallel to the lengthwise extent of the image receiving tape  24  through a print zone  62  defined between the print head  22 , 122  or  222  and the platen  34  or  234  respectively. In this way, an image can be printed on the image receiving tape  24  as it passes through the print zone  62 . 
     The cutting arrangements described in relation to the fifth and sixth embodiments can be incorporated in any of the embodiments described hereinbefore. 
     The print head  22 ,  122 ,  222  is a thermal print head comprising a column of a plurality of printing elements. The print head is preferably only one element wide and the column extends in a direction perpendicular to the lengthwise extent of the image receiving tape  24 . The height of the column of printing elements is preferably equal to the width of the image receiving tape to be used with the tape printing apparatus  2 . With embodiments of this invention, where more than one width of image receiving tape  24  is used, the print head column will generally have a height suitable for printing on the largest width of tape  24 . An image is printed on the image receiving tape  24  column by column by the print head  22 ,  122 , or  222 . 
     The basic control circuitry illustrated in FIG. 9 comprises a microprocessor chip  64 . The microprocessor chip  64  has a read only memory (ROM)  66 , a microprocessor  68  and random access memory capacity  70  indicated diagrammatically by RAM. The microprocessor  68  is controlled by programming stored in the ROM  66  and when so controlled acts as a controller. The microprocessor chip  64  is connected to receive label data input to and from the keyboard  4 . The microprocessor chip output is connected to drive the display  14  via the display driver chip  16  to display a label to be printed (or a part thereof and/or a message or instructions for the user. It should be appreciated that the display driver  16  may form part of the microprocessor chip  64 . 
     The microprocessor chip  64  also outputs data to drive the print head  22 ,  122 ,  222  to print an image on the receiving tape  24  to form the label. The microprocessor chip  64  also controls the motor  42  for driving the image receiving tape  24  through the tape printing apparatus. The motor  42  may be a dc motor which continuously drives the image receiving tape  24  through the print zone  62  during printing. Alternatively, the motor  42  may be a stepper motor. In this situation, the drive roller  30  or platen  234  rotates stepwise to drive the image receiving tape  24  in steps through the print zone  62  during the printing operation. 
     The microprocessor chip  64  may also control the cutting arrangement  50  or blade  124  to allow lengths of image receiving tape to be cut off after an image has been printed thereon. The cutting arrangement  50  or blade  124  may alternatively be manually operated. 
     A fourth embodiment of the invention is shown in FIGS. 10 to  16 . The tape printer  2  according to this embodiment is generally brick shaped, and has on its upper end a tape cassette  443  inserted into a corresponding slot, the latter being shown more detailed in FIGS. 14 a-e . A keyboard on the front left side of the tape printer is schematically indicated with reference numeral  4 , although the keys as such are for reasons of simplification not shown. The printing mechanism is included into the top part of the tape printer, while the batteries providing the necessary electrical energy are situated inside the lower part of the housing covered with the keyboard  4 . The printed tape emerges from an outlet  426  out of the housing of the tape printer  2 . A display  14  is provided above the keyboard  4 , such that a user can easily see and check his or her inputted data. The cassette  443  has an additional feature (which is not provided in the tools according to the remaining embodiments of the present invention); it provides a bend of 90° in the tape before printing. This will be shown more clearly in FIGS. 11-13. Hence the tape  24  emerges in the plane of the display  14  out of the outlet  426  of the tape printer  2 , thus making it easier for the user to control the printed image. 
     FIG. 11 shows a view into the cassette  443  of the fourth embodiment. It houses a supply spool  32  of image receiving tape  24 . The image receiving tape  24  is guided from the supply spool around a pin  401  extending orthogonally to the plane of the side wall of the cassette  443  on which the supply spool  32  lies. The pin  401  is located at the lower left corner of the cassette  443 , and deflects the tape for 90°, such that it extends rightwards in FIG. 11, after it has passed the pin  401 . Additionally to the deflection performed by pin  401 , the tape is downstream the pin  401  lying on a angled, triangular surface  410 , which encloses an angle (in this embodiment of 45°) with the length axis of the pin  401 . Consequently, the tape  24  is bent by pin  401  and surface  410  such that the image receiving tape  24  extends at the right, downstream end (which is indicated by the dotted line  470 ) of the angled surface  410  in the plane of the drawing. Thus, the angled surface is designed such that its left end adjacent the pin  401  is extending orthogonally to the plane of FIG. 11, and that its right end  470  extends parallel to the plane of FIG.  11 . The right end  470  of surface  410  is located close to the left edge of a window  466  in the housing of the cassette  443 . The window  466  is indicated with two parallel dotted lines and is required in order to let a print head  422  and a platen  434  interact in order to print upon the image receiving tape  24 . Consequently, the window  466  has the same function as the window  244  in FIG.  3  and window  266  in FIG.  7 . At the right end of the cassette  443  an outlet  465  is provided, through which the image receiving tape  24  emerges after it has passed the printing location at window  466 . The outlet  465  is shaped similarly to the nose portion  262  shown in FIG.  8 . Thus, it has a box-shaped cross section enclosing the image receiving tape  24 . This cross section is obtained by a bar  407  extending parallel to the plane of FIG. 11, but having an appropriate distance to the adjacent bottom wall  472  (see FIG. 12) of the cassette  443 . A cutting mechanism (not shown) for separating the printed image receiving tape is located downstream the outlet  465 . 
     On the bottom edge (in FIG. 11) of the cassette  443 , a surface  446  having a lengthwise extension in the direction in which the cassette  443  is inserted into the tape printer  2  is provided. This surface  446  serves to control the position of the printhead  422  with respect to the platen  434  when the cassette  443  is inserted into the tape printer  2 . This will be shown more detailed with reference to FIGS. 14 a-   14   e.    
     The housing of the cassette  443  consists essentially of two moulded parts, one of which being a bottom wall  472 , and the other one being a cover wall  473 , as indicated in FIG.  12 . These walls enclose the tape supply spool  32 , pin  401 , and further parts. FIG. 11 shows a view onto the cover wall  473 . It should be noted that the surface  446  can be provided either on the bottom wall  472 , or on the cover wall  473 , like in the embodiment shown in FIGS. 11-13. 
     The cassette  443  is provided on its bottom wall  472  with an upstanding projection  403  having a rectangular cross section and extending parallel to the lengthwise direction of the surface  446  for controlling the printhead position. This can best be seen in FIG. 12 showing a side view onto the cassette  443  of FIG.  11 . The upstanding projection  403  is located at about ⅓ of the height of the cassette  443 . In the cover wall  473  of the housing of the cassette  443 , a recess  404  is provided which extends parallel to the upstanding projection  103 , and is located at the same height. The cross section of the recess  404  corresponds to the cross section of the upstanding portion  403 . The purpose of upstanding projection  103  and recess  104  is twofold: On one hand, they interact with corresponding parts of the cassette receiving slot  475  in order to provide a guidance for the cassette  443  when it is inserted. On the other hand, they allow to stack two or more cassettes  443  together, without any additional elements, thus making storage of cassettes simpler. 
     FIG. 13 shows a perspective view of the cassette  443 . It is apparent that the distance between surface  446  and the bottom wall  472  varies with increasing distance from the front edge of the cassette  443  which it is inserted in the first place into the tape printer  2 . This is necessary in order to control the position of printhead  422  and platen  434  appropriately. 
     FIGS. 14 a-e  illustrate how cassette  443  and tape printer  2  interact during insertion of the cassette. As shown in FIG. 14 a , a slot  475  is provided in the tape printer  2  into which the cassette is to be inserted for printing upon the image receiving tape  24 . Within the slot  475 , a platen  434  and a print head  422  are provided. The platen  434  is driven by a motor (not shown) and located within a recess in a wall of the slot  475 . The recess protects the platen  434  against unwanted damages. The printhead  422  is mounted on a printhead holder  468 , which is pivotally supported on a pin  469 , and spring biased towards the platen  434 . When no cassette is inserted, the printhead and the platen are thus in touch with each other. A sensing pin  467  is provided on the printhead holder  468  for interacting with the surface  446  of the cassette  443 , and controlling the position of the printhead  422 . In the described embodiment, the print head  422  is a thermal print head, but it could be an ink jet printhead, as well. The axis of the printing elements of the printhead  422  extends parallel to the axis of the platen  434 , and within the plane of the image receiving tape  24 , when it is located at the window  466 , thus enclosing an angle of 90° with the center axis of the tape supply spool  32 . 
     In FIG. 14 a , the cassette  443  has just been inserted into the tape printer  2 . Thus, the cassette  443  is only shifted some millimeters into the slot  475 , and the sensing pin  467  does not touch the surface  446  of the cassette  443 . Consequently, the printhead holder  468  is in its rest position, wherein the printhead  422  is touching the platen  434 . 
     In FIG. 14 b , the cassette  443  is moved somewhat deeper into the slot  475 . The sensing pin  467  is in touch with the surface  446  of the cassette  443 . It is apparent that the position of the sensing pin  467  depends on the distance between the point where it touches the surface  446  and the bottom wall  472  of the cassette housing. With other words, the sensing pin  467  scans the shape of the surface  446 . Since the surface  446  (its cross section shown in FIGS. 14 a-e ) is approximately sinusoidally curved, the surface  446  has caused the sensing pin  467  to move downward, and thus to rotate the printhead holder  468  clockwise. Consequently, the printhead  422  is separated from the platen  434 . This is necessary for introducing the image receiving tape  24  between printhead  422  and platen  434 . 
     In FIG. 14 c , the sensing pin  467  is located near the point of the surface  446  having the largest distance between surface  446  and bottom wall  472 , ie. the sensing pin is near its peak position. The printhead holder  468  has consequently rotated further such that the printhead  422  is as far as possible away from the platen  434 , and nearly touches the wall of the slot  475  opposite to the platen  434 . It is thus easily possible to insert the image receiving tape  24  between platen  434  and printhead  422 . 
     In FIG. 14 d , the cassette  443  is even further shifted into the slot  475 . Since the distance between the surface  446  and the bottom wall  475  is now decreased, the sensing pin  467  has caused the (biased) printhead holder  468  to rotate counterclockwise such that the printhead  422  has moved towards the platen  434 . 
     FIG. 14 e  illustrates the final, operative position of the cassette  443 . The printhead  422  cooperates with the platen  434  through the window  466  in order to print upon the image receiving tape  24 . The printhead holder  468  further arrests the cassette  443  in the operative position since it engages with the window  466 . When the cassette  443  is moved out of the slot  475 , the printhead holder  468  moves in the reverse direction through the positions indicated in FIGS. 14 a-e . The cassette  443  thus provides a surface  446  which interacts with the printing mechanism of the tape printer  2  for allowing easy insertion and removal of the cassette. It should be noted that it would be possible to provide a spring for biasing the printhead  422  towards the platen  434  with a sufficient strong force, such that the user only needs to shift the cassette  443  such far that the sensing pin  467  gets into the peak position (FIG. 14 c ), and can then release it, while the spring moves the cassette into the operative position (FIG. 14 e ) or out of the tape printer (FIG. 14 a ). Thus, an over center mechanism as shown in FIGS. 5 and 6 could be provided in the fourth embodiment of the invention, as well. 
     FIGS. 15 and 16 illustrate another advantage associated with the 90° bend in the image receiving tape  24  within the cassette  443  before (ie. upstream) the printing position. This 90° bend allows to dispense with a gear train for driving the platen  434  behind the cassette  443 . Thus, a thinner tape printer can be achieved. As shown in FIG. 15 and 16, the motor  42  is located below the cassette slot  475 , and within the plane defined by the supply  32  of image receiving tape, and by the cassette  443  housing the supply  32 . A gear train  480  is provided for driving the platen  434 , wherein the gears are situated below the cassette  443 , ie. between motor  42  and platen  434 , and approximately lie within the same plane as the motor  42 . Since the driving shaft of the motor  42  extends horizontally in FIGS. 15 and 16, and the platen  434  rotates around a vertically extending axis, there is a part of the gear train, ie. a pair of gears, provided which alters the rotation direction for 90°. The driving shaft of the motor  42  and the rotational axis of the platen  434  extend parallel to the plane defined by the supply  32  of image receiving tape, ie. within the plane of FIG.  15 . FIGS. 15 and 16 further show the position of batteries  481  in the lower part of the tape printer  2 . 
     Reference will now be made to FIG. 17 which shows a fifth embodiment of a cassette receiving bay  18  with the lid  40  removed. The cassette receiving bay  18  has a thermal print head  22  for printing an image onto a supply of image receiving tape  24 . As will be described in more detail hereinafter, the print head  22  is mounted on a printhead arm  26  which is pivotable about pivot point  28 . A drive roller  30  is driven by a dc motor  42  (see FIG. 9) and rotates in the direction of arrow A in order to drive the image receiving tape  24  through the tape printing apparatus. The cassette  20  housing the supply of image receiving tape  24  is received in the cassette receiving bay  18 . The cassette  20  holds a supply spool  32  of image receiving tape  24 . The image receiving tape  24  may comprise an upper layer for receiving a printed image on one of its surfaces and its other surface coated with an adhesive layer to which is secured a releasable backing layer. The image receiving tape  24  is guided by a guide mechanism (not shown) through the cassette  20 , out of the cassette  20  through an outlet O, past the print head  22  to a cutting location C′. The image receiving tape  24  comprises a thermally sensitive material on which an image is printed when in contact with activated or heated elements of the thermal print head. No ink ribbon is required in order to print an image on the thermally sensitive image receiving tape  24 . Some of the embodiments described herein may be modified so that ink ribbon is also provided in the cassette. In these embodiments the image receiving tape may not be thermally sensitive. An image would then be printed on the image receiving tape via the ink ribbon. 
     A cutting arrangement  50  is provided at the cutting location C′. The cutting arrangement  50  comprises a blade support member  52  which carries a blade  54 . The cutting arrangement  50  also comprises an anvil  56  against which the blade  54  acts. In this way, a portion of the image receiving tape  24  on which an image has been printed can be separated from the supply of image receiving tape to thereby define a label. 
     The cassette  20  has a platen  34  in the form of, for example, a flat substantially planar resilient pad, mounted on the outside of the housing  35  of the cassette  20 . In particular, the housing  35  of the cassette  20  has a side wall  37 , parallel to the axis of rotation of the supply spool  32 , which confronts the print head  22 . The platen  34  is provided on the surface of this wall  37 . This platen  34  may be of any suitable material such as rubber or the like. The platen  34  is arranged so that in use the platen  34  comes into contact with the print head  22  with the image receiving tape  24  therebetween. The print head  22  can then act against the platen  34  during printing to provide a good quality image. 
     An idler roller  36  is also provided in the cassette  20  which cooperates with the drive roller  30  in the tape printing apparatus to drive the image receiving tape  24  through the tape printing apparatus  2 . The idler roller  36  is partially housed in the cassette  20  and partially extends outwardly of the side wall  37  on which the platen  34  is arranged. As the drive roller  30  rotates in the direction of arrow A, the drive roller  30  causes the idler roller  36  to rotate in the direction of arrow B. 
     Both the print head arm  26  and the drive roller  30  are resiliently mounted so as to be biased in a direction towards the cassette  20 . In particular, the print head arm  26  is arranged to urge the print head  22  against the platen  34  when the cassette  20  is inserted in the cassette receiving bay  18 . Likewise, the drive roller  30  is biased so as to be urged against the idler roller  36  so that the image receiving tape  24  can be driven by the rotation of the drive roller  30  through the tape printing apparatus  2 . 
     The cassette  20  is inserted in the cassette receiving bay  18  in the direction of arrow C. The platen  34  on the side wall  37  of the cassette  20  comes into contact with the biased print head  22 , with the image receiving tape  24  being between the platen  34  and the print head  22 . Good contact between the print head  22  and the platen  34  is ensured by the biasing of the print head  22  in the direction towards the platen  34 . The idler roller  36  also comes into contact with the drive roller  30 , again with the image receiving tape  24  therebetween. As a result of the biasing of the drive roller  30 , the drive roller  30  is urged against the idler roller  36  so that the image receiving tape  24  can be driven through the tape printing apparatus  2  as a result of the rotation of the idler roller  36  and the drive roller  30 . 
     The cassette  20  is retained in place by clips  38 . The clips  38  are provided in the cassette receiving bay  18  and clip over the cassette  20  to retain it in place. These clips  38  may be manually operated by the user. In one preferred embodiment, the clips  38  automatically engage the cassette  20 , when the cassette  20  is inserted into the cassette receiving bay  18 . To remove the cassette  20 , the user manually moves the clips  38  out of place. It should be appreciated that any suitable clip or catch member can be used to retain the cassette  20  in place. The clips  38  are arranged to engage the two corners  41  and  43  of the cassette  20  which are further from the print head  26  and the drive roller  30 . The cassette  20  could alternatively be released from the clips  38  by activating a button or lever provided externally of the cassette receiving bay  18 . 
     In a modification to this embodiment, the cassette bay lid  40 , which may be hinged or sliding, is arranged to push the cassette  20  into the operative position as the lid  40  is closed. Members which protrude from the lid  40  into the cassette receiving bay  18  may be used to push the cassette into position. The lid  40  may then itself latch to retain the lid closed and the cassette  20  in position. 
     Reference will now be made to FIG. 18 which shows a modification to the embodiment shown in FIG.  17 . Like parts are indicated by like reference numerals and accordingly only those parts which are different will be described. The cassette  120  is provided with a planar drive surface  136  on the same wall  137  of the cassette  120  on which the platen  34  is defined. This drive surface  136  is of a low friction material and replaces the idler roller  36  of the first embodiment. The drive surface  136  cooperates with the drive roller  30  which is biased towards the drive surface  136  to drive the image receiving tape  24  through the tape printing apparatus. 
     The cassette  120  is provided with a slot  122 . When the cassette is in the cassette receiving bay  118 , a cutter blade  124  is arranged to move into the slot  122  during a cutting operation to thereby separate the image receiving tape  24  on which an image has been printed from the supply  32  of image receiving tape. The cut portion of image receiving tape  24  defines a label and exits the cassette receiving bay  118  through slot  126 . 
     The cassette receiving bay  118  is additionally provided with a pair of arms  138  for retaining the cassette  120  in position. The arms  138  are made of a resilient material and are biased to adopt the position shown in FIG.  18 . The free end  139  of each arm has an angled surface  140 . As the cassette  120  is inserted into the cassette receiving bay  118  in the direction of arrow D, the corners  121  of the cassette  120  adjacent the wall  137  supporting the platen  34  and the drive surface  123  engage the angled surfaces  140  and urge the arms  138  away from each other. The arms  138  are held by the sides  144  of the cassette  120  in this position until the cassette  120  is fully inserted, and the other two corners  141  of the cassette  120  have passed the angled surfaces  140 . The arms  138  move in a direction towards one another so as to be once more in the position shown in FIG.  18 . As mentioned hereinbefore the arms  138  are biased to the position shown in FIG.  18 . The other two corners  141  of the cassette  120  are accommodated in corners  142  defined at the end of each arm  138  between the free end  139  and a main portion  143  of each arm  138 . The cassette  120  is thereby retained in position by the arms  138  with the print head  22  biased against the platen  34  and the drive roller  30  biased against the drive surface  136 . 
     When the cassette  120  is fully received in the cassette receiving bay  118 , the side walls  144  of the cassette  120 , perpendicular to the wall  137  on which the platen  34  and the drive surface  121  are supported, are in contact with protrusions  146  defined on the main portions  143  of the arms  138 . The combination of the protrusions  146  together with the corners  142  of the arms  138  retains the cassette  120  in the cassette receiving bay  118  and prevents significant movement of the cassette  120 . 
     When the cassette  120  is to be removed from the cassette receiving bay  118 , the arms  138  are pushed together by applying an inward pressure at area  135  and in the direction indicated by arrows E. This causes the arms  138  to move about a pivot region defined by the protrusions  146 . The free ends  139  of the arms  138  therefore move in a direction away from each other and the cassette  120  can be removed from the cassette receiving bay  118  as the arms  138  no longer retain the cassette  120  in position. 
     By using a flat platen, as in the fifth and sixth embodiments, which cooperates with the print head rather than a curved roller, as in the prior art, the costs of manufacturing the tape printing apparatus can be reduced. This is because the curved nature of the prior art roller surface imposes tight restrictions on the allowable position of the print line relative to the roller platen. In other words, there is an optimum line on the platen at which contact should be made with the print head. In contrast, with a flat platen, the area of the platen on which contact can be made with the print head to achieve good quality printing is much larger. This leads to lower production costs as the relative position of the print head and platen is not as critical as in the prior art. 
     The above embodiments may be modified so that the cassette receiving bay lid  40  is replaced by a much smaller opening through which the cassette is inserted in the direction of arrow C or arrow D. In particular the cassette is inserted in a direction parallel to the planar surfaces defining the upper and lower surfaces of the cassette. The provision of a relatively large lid cover over the cassette receiving bay may has the disadvantages that the appearance of the product may be compromised and that the large lid is a weak point if the tape printing apparatus is dropped. The use of the relatively small opening may overcome these disadvantages. In particular, the cassette receiving bay may have an opening corresponding to the maximum cross-sectional dimension of the cassette. In contrast, the prior art arrangements require a cassette bay opening at least as large as the maximum planar dimension of the cassette. 
     The above described embodiments may have the advantage that tape jamming resulting from the tape catching on the printing mechanism can be reduced. In particular, in the known arrangements, the tape has to be dropped down between a platen and a print head which are both provided by the tape printing apparatus. During insertion the tape may snag on the edge of the print head or the platen which may lead to subsequent jamming. In the first and second embodiments, the platen is provided on the cassette. Accordingly, the cassette can be inserted in the direction of arrow C or arrow D and the tape is not dropped down into position as in the known arrangements. The tape is thus less likely to snag leading to fewer tape jams.