Patent Publication Number: US-2007098473-A1

Title: Tape printing apparatus and tape cassette

Description:
The present invention relates to a tape printing apparatus, a tape supply for a tape printing apparatus and also to a tape cassette with a tape supply for use in a tape printing apparatus. In particular, the present invention relates to a tape printing apparatus for direct thermal printing, a tape supply comprising a tape of direct thermal media for use with a tape printing apparatus and to a tape cassette housing said tape for use in a tape printing apparatus.  
      Tape printing apparatus utilising direct thermal printing are known in the art. For example, the Casio KP-C10 comprises a printer for use with a PC. This printer has a tape receiving portion for receiving a roll of thermal paper tape, a platen and a thermal print head, wherein, during operation, the platen rotates and the tape passes between the platen and the print head with the print head heating the tape so as to form an image on the tape. However, this printer is only capable of printing black images on a white thermal tape.  
      Tape printing apparatus for colour printing have been suggested. However, these apparatus utilize cassettes having coloured ink ribbons with the coloured ink being transferred from the ink ribbon to a receiving tape using a thermal print head. For different coloured images, multiple ink ribbons of different colours are required. These may be loaded into a printer at the same time which increases the size of the apparatus. Alternatively, printing may be suspended and the ink ribbon replaced with a different colour before continuing printing in order to produce a different coloured image. This arrangement increases the time required to produce different coloured images. Also, these printers do not produce full colour images but rather print in one colour and then print in a different colour.  
      In an alternative arrangement, EP-A-0,641,663 discloses a tape printer capable of forming multi-colour printing utilising a single tape cassette and ink ribbon. The tape cassette is housed in the tape printer and comprises a print tape and an ink ribbon formed from different coloured ink portions at a set pitch in the lengthwise direction of the print tape. The tape printer is constructed so that ink ribbon and the print tape are transportable in a forward direction for printing, the ribbon take-up mechanism stops and the platen is moveable away from the printing section after which the tape transport mechanism reversibly transports the printing tape for over-printing of a different colour whereby a multicoloured image is generated. The single multicoloured ribbon solves the problem of having multiple ribbons. However, exact alignment for over-printing of coloured images to produce a multicoloured image is difficult and misalignment leads to images of poor quality. Furthermore, multiple over-printing, rewinding and/or replacement of ink ribbon cassette can lead to creasing of the ink ribbon or jamming of the ink ribbon and/or print receiving tape within the print mechanism.  
      Embodiments of the present invention aims to address one or more of the above-mentioned problems.  
      Referring to  FIG. 1 , a known direct thermal printing medium in the field of photography comprises a base layer  2 , a print layer  4 , and an overcoat layer  6 . The printer layer  2  comprises an acid  8  (the developer) and a colourless die precursor  10 . No reaction occurs until heat from a thermal print head  12  causes the acid  8  and the dye  10  to react, whereupon a colour is formed. The optical density of the colour increases with increasing temperature and time of heating. Monochromatic images are most commonly black and white. However, monochromatic images can be produced in different colours by using different leuco dyes.  
      Conventional methods for colour thermal imaging such as thermal wax transfer printing and dye diffusion thermal transfer typically involve the use of separate donor and receiver materials. However, recently various direct thermal media have been developed in the field of photography to achieve multicolour direct thermal printing. For example, WO 02/096665 discloses a multicolour imaging system wherein at least two, and preferably three, different image forming layers of a thermal imaging member are addressed at least partially independently by a thermal print head by controlling the temperature of the thermal print head and the time thermal energy is applied to the image-forming layers. Each colour of the thermal imaging member can be printed alone or in a selectable portion to the other colours. That is, the temperature-time domain is divided into regions corresponding to the different colours it is desired to combine in a final print.  FIG. 2  is a graphical representation illustrating the temperature and time parameter features of such a direct thermal media for printing magenta, cyan and yellow. The temperature selected for the colour forming regions generally are in the range of from about 50° C. to about 450° C. The time period for which the thermal energy is applied to the colour forming layers of the imaging member is preferably in the range from about 0.01 to about 100 milliseconds.  
      A number of image-forming techniques may be exploited including thermal diffusion with buried layers, chemical diffusion or dissolution in conjunction with timing layers, melting transitions and chemical thresholds.  
      Referring now to  FIG. 3 , there is seen a pre-colour thermal imaging member that utilises thermal delays to define the printing regions for the colours to be formed. The three colour imaging member  14  includes substrate  16 , cyan, magenta and yellow image-forming layers,  18 ,  20 ,  22 , respectively, and spacer interlayers  24 ,  26 .  
      Where the image member is heated by a thermal print head from above, the cyan image-forming layer  18  will be heated almost immediately by the thermal print head after the heat is applied, but there will be a significant delay before the magenta image-forming layer  20  and the yellow image-forming layer  22  are heated according to the thermal conductivity and thickness of the spacer layers  24 ,  26 . To provide multicoloured printing it is preferable that each image-forming layer is arranged to be activated at a different temperature. This result can be achieved, for example, by arranging the image-forming layers to have different melting temperatures or by incorporating in them different thermal solvents, which will melt at different temperatures and liquefy the image-forming materials. For example, if the activation temperature for the cyan layer is T 1 , the activation temperature for the magenta layer is T 2  and the activation temperature for the yellow image-forming layer is T 3 , then the activation temperatures may be selected such that T 1 &gt;T 2 &gt;T 3 . Accordingly, application of a temperature between T 2  and T 3  for a relatively long time period will produce a yellow colour without any cyan or magenta colour. A relatively short, high temperature heat pulse above T 1  will produce a cyan colour without any magenta or yellow colour. Application of a temperature between T 1  and T 2  for a suitable length of time will produce a magenta colour. Accordingly, by varying the temperature and time of heating, individual colours or mixtures thereof may be produced so as to generate a multicolour image.  
      Various arrangements of layers and suitable materials for forming such layers are disclosed in WO 02/096665 and the documents cited therein.  
      According to the present invention, there is provided a tape supply for use in a tape printing apparatus, said tape supply comprising a roll of direct thermal image tape, said direct thermal image tape comprising a plurality of thermally activated colourants and at least one developer for producing a multi coloured image on said direct thermal image tape when said direct thermal image tape is heated.  
      According to the present invention, there is further provided a tape cassette for use in a tape printing apparatus, said tape cassette comprising a body housing a supply of the above-mentioned direct thermal image tape.  
      According to the present invention, there is further provided a tape printer comprising a tape supply receiving portion for receiving a supply of tape, a print head comprising a plurality of printing elements for printing an image on a tape, a drive means for driving a tape passed the print head and a control means for controlling the plurality of printing elements, wherein the control means is adapted to control the printing elements for producing a multicoloured image on a tape by direct thermal transfer.  
      According to the present invention, there is further provided a method of printing a label comprising driving a direct thermal tape passed a thermal print head and controlling the print head whereby a multicoloured image is produced on the tape by direct thermal transfer in a single pass.  
      Embodiments of the present invention provide a tape printing apparatus and a tape cassette/tape capable of printing monochromatic images of continuously variable optical density and/or full multicoloured images using direct thermal printing. 
    
    
      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 schematic diagram of a prior art arrangement for direct thermal printing.  
       FIG. 2  shows a graphical representation of the temperature-time domain for a prior art photographic medium, the temperature-time domain being divided into regions corresponding to the different colours it is desired to combine in a final print.  
       FIG. 3  shows the prior art photographic medium utilized to produce the divided temperature-time domain indicated in  FIG. 2 .  
       FIG. 4  shows a schematic diagram of an embodiment of a tape printing apparatus according to the present invention;  
       FIG. 5  shows a schematic diagram of an embodiment of a cassette receiving bay of the tape printing apparatus shown in  FIG. 4 ;  
       FIG. 6  shows a schematic diagram of an embodiment of a cassette according to the present invention;  
       FIG. 7  shows a schematic diagram of an alternative embodiment of a direct thermal tape printer according to the present invention in which a roll of direct thermal tape is introduced directly into the tape printer;  
       FIG. 8  shows a schematic diagram of an embodiment of direct thermal tape according to the present invention;  
       FIGS. 9   a  to  9   d  show four different examples of face material embodying the present invention;  
       FIGS. 10   a  and  10   b  show two different examples of label material and how those materials are used in a tape printer;  
       FIGS. 11   a  to  11   d  show various examples of print stations which can be used in embodiments of the present invention;  
       FIG. 12  shows schematically the control of a print head for use in some of the arrangements shown in  FIG. 11 ;  
       FIG. 13   a  to  13   c  show various menus for selecting colours;  
       FIGS. 14   a  to  14   c  show the menus which are displayed for selecting the background of a label;  
       FIG. 15  shows schematically control circuitry for controlling a tape printing device embodying the present invention;  
       FIG. 16  shows a schematic cross sectional view of a tape printer embodying the present invention;  
       FIG. 17  shows an example of two labels separated by a full cut with one of the labels having a partial cut;  
       FIG. 18  shows schematically an arrangement for providing the full cut and partial cut of  FIG. 17 ;  
       FIG. 19  shows a label with background printing;  
       FIG. 20  shows schematically the arrangement for printing a background image on a tape;  
       FIG. 21  shows schematically the arrangement for printing a background image on a die cut label; and  
       FIG. 22  illustrates an method for providing the labels of  FIG. 17 . 
    
    
      FIGS.  1  to  3  indicate prior art and have already been discussed in the pre-amble of this specification.  
       FIG. 4  shows a schematic diagram of an embodiment of a tape printing apparatus  28  according to the present invention. The tape printing apparatus comprises a keyboard  30  and a cassette receiving bay  32 . The keyboard has a plurality of data entry keys  34  such as numbered, lettered and punctuation keys for inputting data to be printed as a label and function keys for editing the input data. The keyboard may also have a print key  36  which is operated when it is desired that a label be printed. Additionally an on/off key  38  is also provided for switching the tape printing apparatus on and off.  
      The tape printing apparatus has a liquid crystal display (LCD)  40  which displays the data as it is entered. The display 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 is driven by a display driver (not shown).  
      Basic circuitry for controlling the tape printing device  1  is shown in  FIG. 15 . There is a microprocessor chip  200  having a read only memory (ROM)  202 , a microprocessor  201  and random access memory capacity indicated diagrammatically by RAM  204 . The microprocessor chip  200  is connected to receive label data input to it from a data input device such as a keyboard  206 . The microprocessor chip  200  outputs data to drive a display  208  via a display driver chip  209  to display a label to be printed (or a part thereof) and/or a message for the user. The display driver alternatively may form part of the microprocessor chip. Additionally, the microprocessor chip  200  also outputs data to drive the print head  216  so that the label data is printed onto the image receiving tape to form a label. Finally, the microprocessor chip  200  also controls the motor  207  for driving the platen. The microprocessor chip  100  may also control the cutting mechanism to allow a length of tape to be cut off. In alternative embodiments at least part of the cutting mechanism may be manually operated.  
      Reference is made to  FIG. 16  which shows in plan view a tape printing device  300  embodying the present invention which has a cassette  306  arranged therein. This cassette can contain a supply of colour direct thermal material as will be discussed in more detail. The cassette  306  is located in a cassette bay  316 . The cassette bay  316  also accommodates at least one thermal print head  304  and a platen  308  which cooperate to define a print zone  302 . Other arrangements for the printing are describe in more detail hereinafter. The print head  3044  is able to pivot about a pivot point  324  so that it can be brought into contact with the platen  308  for printing and moved away from the platen  308  to enable the cassette  306  to be removed and replaced. In the operative position, the platen  308  is rotated to cause the image receiving tape  310  to be driven past the print head  304 .  
      The platen  308  is driven by a DC motor (see  FIG. 15 ) so that it rotates to drive the image receiving tape  310  through the print zone  302  of the tape printing device  301  during printing. In this way, an image is printed on the tape and fed out from the print zone  302 .  
      The image is printed by the print head  304  on the image receiving tape  10  on a column by column basis with the columns being adjacent one another in the direction of movement of the tape  310 . Pixels are selectively activated in each column to construct an image in a manner well known in the art. The DC motor is provided with a shaft encoder for monitoring the speed of rotation of the motor. The control of the speed of the motor is achieved by the microprocessor chip  100  (see  FIG. 15 ) to generate data strobe signals each of which causes a column of pixel data to be printed by the print head  304 .  
      The tape printing device may include at cutting location  320  a cutting mechanism  328  which carries a blade  318 . The blade  318  cuts the image receiving tape  310  then enters a slot  330  located in the cassette  306 .  
      It is understood that other embodiments of the tape printer may be envisaged. For example, the tape printer of the present invention may be a PC printer rather than a stand-alone printer. In such a printer, a keyboard and display means are not essential as the data may be input and displayed on the PC. The PC then acts as an input device for the printer. Alternatively, other apparatus may be used to input data to the printer for printing. For example, in an embodiment of the invention a digital camera may be used to input data to the tape printing device for printing. Images may alternatively be input using a smart card, chip card, memory card or the like.  
       FIG. 5  shows a schematic diagram of a cassette receiving bay  32  in the tape printing apparatus. The cassette receiving bay is arranged to receive a cassette housing a supply of direct thermal tape. The cassette receiving bay is generally covered by a cassette bay lid.  
      The cassette is intended to cooperate with a thermal printing device. The printing device carries a print head  40  and a platen  42 . The print head is moveable between an operating position in which it is in contact with the platen and in which the image receiving tape is pinched between the print head and the platen and an inoperative position in which the tape is released to enable the cassette to be removed. With the print head in the operative position, an image may be formed on the image receiving tape as a result of collectively heating pixels on the thermal print head. In alternative embodiments of the present invention, the print head may be stationery and the platen moves between an inoperative and operative position. Once a message has been printed, the image receiving tape is fed out of the cassette to a cutting apparatus  44 .  
       FIG. 6  shows as schematic diagram of the cassette  50 . The cassette comprises a body  52  housing a supply of direct thermal tape  54 . The direct thermal tape comprises a first side on which a printed image is formed and a second side comprising a releasable backing layer. The structure of the direct thermal tape is described in more detail hereinafter. The direct thermal tape is guided out of the cassette and through the print zone  56  between the platen and the thermal print head.  
      It is understood that other embodiments of the tape printer may be envisaged in which the receiving bay received a roll of direct thermal tape without the need of a cassette as shown in  FIG. 7 . This may reduce the cost of replacing the tape supply. However, the use of a cassette to house the tape ensures that the tape remains in good condition both during storage and when introduced into a printer for use. It is also preferably that the cassette be light tight as excessive exposure of light to some tapes may have an adverse effect. In some embodiments of the invention, the tape is wound on the tape supply roll so that the thermally sensitive surface is inwards of the tape with the backing layer radially outwards.  
      The direct thermal tape for use in the tape printer embodying the present invention comprises direct thermal printing media of the type utilized in the field of photography and discussed in the pre-amble of this specification with reference to FIGS.  1  to  3 . While conventional tape printers capable of colour printing utilize separate donor and receiver tapes, in the present invention the thermally activated chemistry is incorporated into a single tape.  FIG. 8  shows a schematic diagram of direct thermal tape according to an embodiment of the present invention. The tape comprises a removable base layer  70 , an adhesive layer  72 , a substrate layer  16 , a print layer  73 , and an overcoat layer  74 . The print layer comprises a plurality of colourless dye precursors in order to form a direct thermal tape capable of producing a full multicoloured image. In this embodiment the different colourless dye precursors are provided in separate image-forming layers  18 ,  20 ,  22  with spacer interlayers  24 ,  26 . After printing a label, the removable base layer may be removed to expose the adhesive layer for attachment of the printed label to a surface.  
      During printing, the print control means in the form of a processor controls the print head whereby dyes of different colours are selectively reacted to produce a multicoloured image. The criteria for selective reactivity depend on the thicknesses of the tape layers, the thermal conductivity of the layers, the temperature coefficients of reaction for the dye precursors, the heating temperature and the heating time. It is envisaged that a number of image-forming techniques may be exploited including thermal diffusion with buried layers, chemical diffusion or dissolution in conjunction with timing layers, melting transitions and chemical thresholds. Selective light activated reactions may also be utilized in order to achieve multicolour colour printing.  
      During printing, the processor controls the print head and in particular, the temperature of each print head pixel is controlled according to data input from the keyboard, PC or other input device. The temperature or energy of each pixel is continuously variable whereby an image of continuously variable optical density and/or colour may be produced. The processor also controls the print head strobe time, that is the width of a pulse and/or the number of pulses. The control of the heating temperature and the heating time allows a multi-coloured image to be produced on the direct thermal image tape.  
      The printer and the tape are adapted to produce a multicoloured image on the tape by direct thermal transfer in a single pass of the tape, that is no reversing of the tape is required. The processor is adapted to control the printing elements according to data input to the tape printer by a user. For example, a user can select different colour schemes for a label via the keyboard. The processor controls the temperature and the time period each printing element is heated and the temperature of each element is continuously variable. In some embodiments, the energy can be varied in a stepwise fashion rather than continuously.  
      A memory is provided for holding temperature, heating period and colour data which is accessible by the processor to select a temperature and heating period for each printing element according to data input to the printer. The memory may hold temperature, heating period and colour data for different types of direct thermal tape as well as for thermal transfer tapes (which use an ink ribbon). In one embodiment the printer has a detection means for detecting the type of direct thermal tape inserted in the printer (for example, it could be a two colour tape or a full multicolour tape) or if it is a thermal transfer tape and the detecting means sends a signal to the control means whereby the data corresponding to the detected tape type is selected. In this way, a tape printer can be used for several different embodiments of direct thermal image tape. The detection means may be physical e.g. the tape cassette may activate a switch according to the shape of the body of the cassette when introduced into the printer. Alternatively, it may be electrical, optical, RF, magnetic, in the form of markings or may be selected by a user manually.  
      The above-described embodiments enable a method of printing a label in which a multicoloured image is produced on the tape by direct thermal transfer in a single pass of the tape past the print head. In particular, the use of such a method solves the problem of alignment between an ink ribbon and a receiving tape and also solves the problem of ink ribbon creasing. As a result, higher quality colour images are achieved.  
      Reference is now made to  FIG. 9  which shows four examples of face material which can be used in embodiments of the present invention. Some of these embodiments are the same or similar to those embodiments described previously. In the following, those layers which are the same are referenced by the same reference numbers.  
      Reference is made first to  FIG. 9   a.  In this arrangement, there is a clear carrier film  106 . On one side of the clear carrier film is a layer  108  containing cyan dye or the like. Overlying that cyan layer  108  is a bottom over-layer  110 . This is a protective layer which may be a polymeric binder in which small molecules are dissolved or dispersed.  
      On the other side of the clear carrier film is a layer  104  containing magenta dye. On top of that magenta layer is a further layer containing yellow dye  102 . That yellow layer  102  is overlaid by a protective over-layer  100  which is similar to the bottom over layer  110 . This defines a first face material  116   a.    
      Reference is now made to  FIG. 9   c.  This face material construction  116   c  has a similar construction to that shown in  FIG. 9   a.  However, the over-layer  100  has been replaced by a clear protection film  112 . The clear protection film  112  is adhered to the layer containing the yellow dye by an adhesive layer  114 . That adhesive layer is clear. The clear protection film may be a thin transparent layer of polyolefin or polypropylene or any other suitable material, typically having a thickness of a range 3 to 15 micro metres for example. The clear protective film may optionally have a wax coating. The clear protective film may be coated in a friction reducing material.  
      Reference is now made to  FIG. 9   b  which shows a further embodiment of the face material. The face material comprises a clear carrier film  106 . On that clear carrier film  106  is provided a layer  108  containing cyan dye. This has a layer  104  containing magenta placed on top of it. On the magenta layer  104  is a layer  102  containing yellow dye. The layer containing the yellow dye  102  has a protective over-layer  100  placed on top of it.  
       FIG. 9   d  shows a modification of the embodiment shown in  FIG. 9   b.  The over-layer  100  of  FIG. 9   b  has been replaced by a clear protection film  112  which is adhered to the yellow layer  102  by a clear adhesive  114 . This is as already described in relation to  FIG. 9   c.    
      The embodiments shown in  FIG. 9  have a clear carrier film. In some embodiments of the invention, the carrier film may be opaque and coloured. Alternatively the carrier film may be transparent and coloured. The embodiments of  FIG. 9  may be modified to include space layers or the like between the coloured layers. Three coloured layers are shown. In alternative embodiments of the invention, there may be only two or one coloured layer. The adhesive layer may be opaque and/or coloured in alternative embodiments of the invention. The cyan layer is show on a different side of the carrier to the yellow and magenta layers in some embodiments. In alternative embodiments of the invention, the yellow or magenta layers may be provided on the other side of the carrier layer to the other two coloured layers. Embodiments of the invention have shown coloured layers with magenta, cyan and yellow. It should be appreciated that in alternative embodiments of the invention there can be different colours in the layers. Depending on the technology used, it is possible that the dyes or the like can be incorporated in a single layer or two or more colours can be produced from the same layer.  
      Reference is made to  FIG. 10  which now shows various embodiments of the label material and how it is used in label in label printers in preferred embodiments of the present invention.  
      Reference is now made to  FIG. 10   a  which shows an embodiment. In this embodiment, two supplies of material are used. The first supply  128  comprises the face material  116 . To the bottom over-layer or clear carrier film is applied a layer of white ink  118 .  
      The second supply of material comprises a double sided silicon liner  122 . One side of the silicon liner layer  122  is provided a layer of white adhesive  120 . As can be shown seen from  FIG. 10   a,  the first supply  128  is provided on a roll. In use, once a label has been printed, the thin silicon liner layer can be removed. This will leave the white adhesive layer exposed and the label can be stuck to any suitable surface. In alternative embodiments of the present invention, the adhesive layer may not be white.  
      The label material  124  of  FIG. 10   a  may be provided in a roll  124 . Depending on the embodiment of the present invention, the roll may be accommodated in a tape cassette as discussed previously. However, this is not necessary and in alternative embodiments of the present invention, the label material may be provided simply in a roll. The label material is then provided to a print station  126  where printing can be carried out. Various examples of print stations will be described later. The second supply material  130  is also provided in a roll or alternatively in a cassette. In some embodiments of the present invention, a common cassette may be provided for both of the supplies  128  and  130 . The material  130  is provided together with the material  128  to a pair of rollers  132  and  134 . These rollers act together to apply the white adhesive and silicon liner material  130  on one hand to the face material and white ink layer on the other hand, to thereby provide a single label. The white ink layer  118  is adhered to the white adhesive layer  120 .  
      It should be appreciated that one or both of the rollers  132  and  134  may be driven. In alternative embodiments of the present invention, a single roller may be used with that single roller acting against a fixed surface.  
      Reference is now made to  FIG. 10   b  which shows a further embodiment for the label material. The face material  116  is provided as one separate supply. As a different supply is provided a material comprising an adhesive layer  190 . Attached to one side of the adhesive layer  190  is a white film  192 . Attached to the other side of the white film  192  is an adhesive layer  193  which is attached to a double sided silicon liner  194 . Silicon is provided on both sides of the liner. This defines a backing supply  196 . The backing supply  196  and face material  116  can be provided on rolls, in a common cassette, or in separate cassettes. As with the arrangement shown in  FIG. 10   a,  the image is printed on the face material  116  at a print station  126 . After printing, the backing material  196  is applied by a pair of rollers  132  and  134  to the face material  116 .  
      Reference is now made to  FIGS. 11   a  to  d  which show various different constructions of the print station.  
      Reference is made first to  FIG. 11   a.  In  FIG. 11   a,  there are two print heads  140  and  146 . The first print head  140  acts in conjunction with a platen  142 . This first print head  140  is arranged to control the yellow and magenta printing with the material shown in  FIGS. 9   a  and  9   c.  The second print head  146  also operates in conjunction with a platen  144  in the form of a roller. The second print head  146  is arranged to control the printing in the cyan layer  108  in the arrangements of  FIGS. 9   a  and  9   c.  It should be appreciated that this same arrangement may also be used with the embodiments shown in  FIGS. 9   b  or  9   d.  In some alternative embodiments of the present invention, the two print heads  140  and  146  may be arranged to contact the same side of the label material to print the image. In this latter embodiment the two print heads would be preferably but not necessarily arranged to contact the top over-layer or clear protective film depending on the construction of the face material.  
      In the arrangement of  FIG. 11   a,  the print head is fully addressable. This means that the print head contains n printing elements each of which is separately controllable. Effectively, this means that a drive circuit is provided for each printing element so that for any given printing operation the printing element can be controlled to be on or off. In  FIG. 11   a  the print head has a height x which corresponds to the maximum width of label to be used with the tape printer. In general, the text will have a maximum height y which is less than the maximum label height x. The term text is used to refer to any image which is printed over a background image and may be text, symbols, numbers, graphics, drawings or the like. This is because there will generally be a space above and below the characters on a label. It should be appreciated that the term “text height” refers to the height of a line of text where the label contains a single line of text or where the label contains more than one line, the height from the top of the first line to the bottom of the last line.  
      Reference is made to  FIG. 11   b  which shows a modification to the arrangement of  FIG. 11   a.  The arrangement of the  FIG. 11   b  shows two print heads  148  and  154  in conjunction with respective platens  150  and  152  in a similar arrangement to that shown and described in relation to  FIG. 11   a.    
      Reference is made now to  FIG. 12  which shows how the print heads of  FIG. 11   b  are controlled. In  FIG. 12 , six printing elements  180   a - f  are shown. This is highly schematic. In practice many more than six printing elements  180  are provided. These printing elements  180  have together provide a height x which is equal to the maximum width of tape used with the tape printer. Pixels  180   c  and  180   d  together provide the part of the print head will be used to print text and thus have a height y. This means that the two pixels  180   a  and  180   b  above the two pixels  180   c  and  180   d  will be used to provide an image above the text and the two pixels  180   e  and  180   f  will be used to provide the image below the text. Typically this image will be a background colour, background pattern or the like as will be discussed in more detail hereafter. In the embodiment shown in  FIG. 11   d,  the pixels which are used to generate text that is pixels  180   c  and  180   d,  each are provided with their own drive circuit  182   b  and  182   c.  The drive circuits  182   b  and  182   c  are controlled by a controller  184 . Since each of the two pixels  180   c  and  180   d  has their own drive circuit, they are independently and separately controllable. In other words, they can both be on both be off or only one of the two on. However, for the two pixels above the text, that is pixels  180   a  and  180   b,  a single drive circuit  182   a  is provided which is again controlled by the controller  184 . This means that these two pixels will either both be on or both be off. It is not possible to separately control these two pixels.  
      Similarly, for the two pixels below the text, that is pixels  180   e  and  180   f,  again a common drive circuit  182   d,  controlled by the controller  184 , is provided. Again, this means that the two bottom pixels with either both be on or both be off. It is not possible to separately control these pixels.  
      As mentioned previously,  FIG. 12  is schematic in that in practice many more than six pixels are provided. The advantage of the arrangement shown in  FIG. 12  is that the cost of the drive circuitry provides a substantial cost of the print head circuitry. By reducing the number of drive circuits required, the cost of the print head can be significantly reduced.  
      In the arrangements of  FIGS. 11   a  and  11   b,  the two print heads together provide both the background and the text. Thus, the background can have any suitable colour or pattern and the text can have any suitable colour or colours. In both of these embodiments, the two print heads will have the same construction in the respective embodiments.  
      Reference is now made to  FIG. 11   c  and  FIG. 11   d  where the printing process is effectively divided up into two stages. In a first stage the text is printed in the desired colour or colours on the tape and then a background is applied to the tape. In alternative embodiments of the present invention, the background to the text may first be applied and then the image.  
      In the arrangement shown in  FIG. 11   c,  the text is printed on to the tape using a print head  173  in conjunction with a platen  172 . The print head will have the same print head structure as described in relation to  FIG. 11   a.    
      The tape will then be provided to a two print head arrangement comprising a first print head  168  and associated platen  164  and a second print head  160  and associated platen  162 . This arrangement is the same as described in relation to  FIGS. 11   a  and  b.  However, in the arrangement shown in  FIG. 11   c,  the print heads are arranged to provide a colour background. Accordingly, the print head has a very much simpler construction in that all of the printing elements are controlled to be either on or off and if on, the energy level and duration is appropriately controlled dependent on the required colour. It should be appreciated that the print head can in effect be replaced by an element which can be heated up to the required temperature for the required duration. The term print head is intended also to cover any such element.  
       FIG. 11   d  shows a modification to the arrangement of  FIG. 11   c  in that the two print heads are now arranged to be aligned with each other so that the need for the platens can be removed. The two print heads  174  and  176  have the same construction as the print heads  160  and  168  described in relation to  FIG. 11   c.    
      The arrangements shown in  FIGS. 11   c  and  11   d  can be modified so that a single background applicator in the form of a single print head is provided. Thus the arrangements shown in  FIGS. 11   c  and  11   d  can be simplified to provide two print heads. One print head is arranged to provide the text or the like on the label and the other print head is arranged to provide the background colour or image. The position of the print head will be determined by the nature of the material. For example, if the full colour image can be achieved by print heads acting from the same side of the material, then the print heads can be provided side-by-side. Alternatively, if the material is such that printing can be achieved from either side of the material, then the two print heads may be provided in alignment with each other, thus avoiding the need for a platen and also providing a compact arrangement. In other words, the print heads act as a platen for the oppositely positioned print head.  
      It should be appreciated that depending on the structure of the material, the number of print heads used can be one, two or three. It should also be appreciated that embodiments of the present invention can be used with direct thermal materials which provide more limited colour images. For example, embodiments of the present invention can be used with di-chromic or tri-chromic materials. In those cases, the number of print heads and print head control may be simplified.  
      It should be appreciated that tape printers embodying the present invention can be used to provide colour images but can also be used with thermal material to provide a single printing colour with no variability in the background colour. In other words, the tape material will have a predetermined colour and an image can be printed in a single colour usually black.  
      Tape printers embodying the present invention can also be arranged to do thermal transfer printing, that is using an ink ribbon.  FIGS. 11   c  and  11   d  show where the thermal transfer cassette would be used. In particular, the thermal transfer cassette would be positioned so that the image is printed on the tape using the print head where each printing element is individually controllable.  
      Reference will now be made to  FIG. 13  to show how a user is able to select the desired colour. The user would operate a function key or keys in order to access colour options. In one embodiment, a colour function key  210  is actuated to provide the menu shown in  FIG. 13   a.  Using the cursor, the user is able to move between background and text. When background is highlighted, the menu shown in  FIG. 13   b  is shown. In order to get to the menu shown in  FIG. 13   b,  the user would move the cursor until the background option is highlighted. The user would then activate a confirmation key such as an OK key or ENTER key. This would then provide the menu shown in  FIG. 13   b.  The user is able to scroll through the various different colours available to the user. To select a colour, the user would activate a confirmation key such as an OK key or ENTER key. This would then take the user back to the menu shown in  FIG. 13   a.  The user can then move the cursor down to the text option. If the confirmation or OK key is actuated, then the menu shown in  FIG. 13   c  will be displayed. In the same way as described in relation to the background colour, the text colour can be selected. Once the OK key has been pressed, then the user returns to the menu shown in  FIG. 13   a.  A further actuation of the OK or confirmation key will take the user back to the edit screen and the user can input an image to be printed.  
      In one embodiment of the present invention, the menu shown in  FIG. 13   a  may show the currently selected colours for the background and text.  
      In another embodiment of the present invention the user may be able to view the choice of colours available to the user by viewing a printout of the available colours. This may be achieved by selecting a ‘colour palette’ option from a menu or by selecting the appropriate key on the keyboard. When the colour palette option is selected the printer may be arranged to print out the available colours together with the name of each colour, so that the user is able to identify the colours printed out by name. This embodiment of the present invention is particularly useful when a monochrome display is used, or when the display is unable to display the full range of colours available to the user.  
      In another embodiment of the present invention, the display may be a colour display and when the user inputs text, the text will have the selected colour on the display. Likewise, the background of the display will also have the required colour.  
      Alternatively, in a further embodiment of the present invention, the colour display may be arranged to display a grid or ‘matrix’ of colours, each region of the matrix displaying a selectable colour. In this embodiment the matrix of colours may be displayed in place of the menus shown in  FIG. 13   b  and  13   c.  Accordingly, after the user has selected either ‘background’ or ‘text’ from the menu shown in  FIG. 13   a,  the printer may be arranged to display the colour matrix. Using the cursor keys the user may be able to select a colour by placing the cursor on the region of the matrix displaying the desired colour. The printer may be further arranged to also display the name of the colour on which the cursor is placed.  
      It should be appreciated that some displays may only be able to display one or two lines of text. In that case, the menus shown in  FIG. 13   a  would not be displayed but the options would be viewed by the user moving the cursor downwards.  
      In some embodiments of the present invention, the tape printer may be connected to a PC. In those embodiments, the tape printer may not have a keyboard or display. However, in some embodiments the tape printer will additionally have the display and keyboard. In the embodiments where the tape printer is connected to a PC, relatively complicated colour images can be downloaded from the PC to the tape printer for printing. These can be full colour images.  
      Reference is now made to  FIG. 14 .  FIG. 14  shows how the user can select the background for the tape. Using one of the function keys, the user is able to get to a background menu as shown in  FIG. 14   a.  This lists the various options for background. By way of example, the user can have no background, a patterned background, a plain background (i.e. a particular colour) or a text background. Using a cursor, the user is able to select one of these options. As described in relation to  FIG. 13 , the user moves a cursor down to the selected option and actuates a confirmation key or the like. If the user selects pattern as the option, then the menu shown in  FIG. 14   b  is displayed. As can be seen, the user has options such as a shaded background, a dotted background, a background with stars or a background with stripes. This is entirely by way of example only and any other suitable pattern can be used as a background. To select a particular pattern, the user presses the cursor to highlight the selected option and then presses or actuates a confirmation key. If the user selects the text option, then the menu shown in  FIG. 14   c  is shown. In particular, a message to the user is provided such as input text or a blank screen. In either case, the user inputs the text which will be displayed as the background. To confirm the input text, the user will actuate or press the confirmation key.  
      If the user selects the plain background, then the user may be taken to the menu shown in  FIG. 13   a.    
      It should be emphasised that embodiments of the invention are not limited to the examples of the tape materials given in this application. Embodiments of the present invention can be used with full colour direct thermal materials or with direct thermal materials which give a selection of two or more possible colours.  
      Preferred embodiments of the present invention are arranged so that information is automatically provided to or detected by the tape printer about the capabilities of the material. In other words whether the material is full colour, a thermal transfer material, a direct thermal material only providing one colour or a colour direct thermal material providing two or more colour options and if so what those colour options are. This information can be provided in a number of different ways. For example, the tape supply and/or cassette may have an element which provides the necessary information. In alternative embodiments of the present invention, the user may be able to set this from the keyboard. In other words, the user will provide the tape printer with information as to the type of tape material so that the tape printer can be controlled accordingly.  
      In embodiments of the preset invention, when the tape printer has received information that a colour direct thermal material is provided, then it can for example automatically display the colour and background text menu shown in  FIG. 13   a  so that the user can keep the current settings or change those settings.  
      Reference is made to  FIG. 17  which shows two labels  400  and  402 . Label  400  has been heated to provide a first background colour whilst the second label  402  has been heated to provide a different background colour. As indicated by reference  404 , there may be a region between the two labels where the colour is a blend between the two colours or the boundary between the colours is not clear. It may be difficult in practice to achieve a clean line between two colours. To address this problem, the region  404  is bounded on one side by a first cut  406  and on the other side by cut  408 . Both of these cuts may be full cuts, that is the cut extends through the tape and any backing tape in its entirety to fully separate the two labels. In preferred embodiments of the present invention, one of these cuts is a partial cut, that is the cut is made only through part of the tape which is to be adhered to the surface and not the backing layer which is discarded. This partial or tab cut is in itself advantageous in that it is easy to remove the label from the backing tape.  
      In some embodiments of the present invention, the two cuts may be partial cuts. This may be desirable where a strip labels is required to be printed, where the labels are not completely separated. This may make for ease of transport. Each of the labels may be removed from the backing layer, with the region  404  as defined by the cut on either side, remaining on the backing tape for easy disposal.  
      It should be appreciated that when the first label  400  is separated from the second label  402 , the downstream label  402  may also be provided with the partial cut and full cut at its downstream end.  
      In this way, the region where the colour is not well defined will be discarded.  
      In one embodiment of the present invention the printer may be arranged to print on the region  404 . The region  404 , which does not comprise part of the label, may then be used to present information to the user.  
      One example of information that could be printed in region  404  would be to provide an indication of the amount of tape remaining in the cassette. This may be achieved by referring to a memory location either in the microprocessor  200  or in a separate memory storage which may be provided, for example, on a processor or RF tag located on the cassette or in a host computer. The amount of remaining tape may be read from the memory location and printed on region  404  during the printing operation of the label.  
      Further examples of information which may be printed on region  404  include: printing a serial number numbering each label of a series of labels; printing arrows to indicate where the tab cut is located; and printing advertising information, such as a website address.  
      Mechanisms for providing partial and full cuts are known and in this regard reference is made to our earlier patents EP 578372, EP 711670, EP 607027 and EP 711637, which are hereby incorporated by reference.  
       FIG. 18  schematically shows one arrangement for providing a tab cut. The arrangements comprises a common holder  410  which holds a first blade  412  and a second blade  414 . The first blade  412  is arranged to provide the partial cut whilst the second blade  414  is arranged to provide the complete cut. The two blades  412  and  414  act against an anvil  416 . The partial cut blade  412  is arranged so that it does not extend as far down as the blade  414  for providing the complete cut. This is indicated by distance  418 . The difference between the lowest points of the two blades  412  and  414  represents the thickness of the backing layer of the tape. The common mechanism  410  is arranged to move the two blades  412  and  414  downwards so that the blades act against the anvil  416 . A tape will of course be provided between the blades and the anvil  416 . In this way, a full cut and a partial cut may be provided. The mechanism for providing the full and partial cut can be varied as required. Instead of providing an up and down motion to provide the full and partial cut, a rolling motion where the blades carried out rolling motion to bring them into and out of contact with the tape. This is described in our patent number EP 711637.  
      In alternative embodiments of the present invention, the cutting operation can be a two stage operation, with a single blade providing the full cut and the partial cut.  
      Reference is made to  FIG. 22  which shows a detailed example of the implementation of one embodiment of the invention. Shown in  FIG. 22  are the relative positions of a first print head  600  and associated platen  602 . Downstream of the first print head  600  is a second print head  604  and its associated platen  608 . Downstream of the second print head  604  is the tab cut blade  610 . Downstream of the tab cut blade  610  is the full cut blade  612 . The various steps performed are shown with the position of the tape relative to the components shown.  
      In step S 1 , the tape has a tab cut  614  and down stream of the tab cut portion is part of the background  616  used in the previous label.  
      In step S 2 , the tape is reversed so that the first print head can start printing the background image for the next label between the tab cut and end of the label. The tab cut needs to be positioned before the first printing line for the background image.  
      In steps S 3 -S 5 , the background image of the label is printed. When the tape reaches the second print head, the overlying image is printed as shown in step S 5 . The background printing and printing of the overlying image can take place at the same time but on different parts of the tape.  
      In step S 6 , the background image has been completed so the first print head is inactive. The second print head continues to print until the overlying image has been completed.  
      In step S 7 , the label on which both the background image and the overlying image has been printed is fed to the cutting position and the tab cut blade activated.  
      In step S 8 , the tape is reversed slightly and the full cut blade activated. This is because it is difficult to cut on the last line that is printed. The full cut is therefore performed at a distance less than the label length. This means that part of the printing will then be on the tab cut portion.  
      Step S 9  is the same as step S 2  but for the next label.  
      Reference is made to  FIG. 19  which shows a label with background printing (ABC LTD constitutes the background image). For clarity, the image printing on top of the background printing has been omitted. In this embodiment, it can be seen that the background image which can be words, a pattern, a plain colour or the like is arranged to extend across the full width of the tape. Thus when printing across the width of the tape it can be ensured that the background covers the entire width of the printing and does not leave a blank space between the edge of the tape and the printed background image.  
      To ensure that printing occurs across the entire width of the tape, ie the dimension of the tape parallel to the longitudinal axis of the print head it is necessary to ensure that the print head is long enough to extend the entire width of the tape. Where different widths can be printed on, the print head can be controlled to activate only those heating elements which are required to print on the width of tape present. To deal with tolerances in tape position and tape width, the print head may be controlled to print over a length slightly greater than the tape width. This may mean that printing may occur on the platen, with no tape between the platen and print head. This is illustrated in  FIG. 20 . The print head  500  is supported by a print head holder  504 . The print head has a height  502 . The tape  512  has a height  510 . The height  510  of the tape  512  is less than the height  502  of the print head and the number of printing elements of the print head activated to be print a background image having a height at least the same size and preferably slightly larger than the width of the image receiving tape. Also shown in this Figure is the platen  506  and its support  508 . The print head prints against the platen.  
      In embodiments of the invention, applied to die cut labels, the print head may be controlled to print over a length slightly greater than the width of the label. In this embodiment, the print head may simply end up printing on the label liner. This is illustrated in  FIG. 21 . The print head  500 , print head holder  504 , the platen  508  and platen holder  508  are as shown in  FIG. 21 . The height of the print head is  502 , the height of the label is  516  and the height of the label liner  520  is  518 . The print head is controlled to print a background image at least the same height as the label and preferably slightly greater. The height of the image is preferably less than the height  518  of the label liner.  
      It should be appreciated that embodiments of the invention are applicable to continuous tape and also, where appropriate die cut labels arranged on a continuous backing layer.