Tape cartridges

Abstract: Even when any of tape cartridges accommodating tapes having different hardnesses, thicknesses or widths are exchangeably mounted in the same printing apparatus, excellent printing can be obtained. In a platen (12) provided in a tape cartridge (10), the harder, thicker or wider the tape (T) accommodated in the tape cartridge (10), the softer a platen rubber. The reason why such a platen rubber (14) having a hardness corresponding to the properties of the tape (T) is used is to obtain an excellent contact state between a printing head and the tape (T) regardless of the properties of the tape (T) when the tape cartridge (10) is mounted in a tape writer. Accordingly, the tape (T) can be excellently conveyed by the platen (12) and a tape guide pin (26) regardless of its properties, and can be brought into contact with a printing head through an ink ribbon (R) in the same contact state. Consequently, excellent printing by the printing head can be obtained.

Description: The present invention relates to tape cartridges which can be mounted in and removed from a printing apparatus include a printing tape and a platen for nipping the printing tape in cooperation with a printing head of the printing apparatus. Printing apparatus for printing a desired string of characters on the front surface of an adhesive tape with an adhesive coated on the rear surface thereof beforehand have been known. Such printing apparatus enable the user to readily and neatly print, for example, a headline or a title on the surface of a tape, the printed tape being easily adhered on the spine or cover of a document file or on the spine of a video tape thereafter. Such printing apparatus are very handy and thus extensively used in industrial fields and households. It is well known that some major objectives in designs of such printing apparatus are reduced size and/or weight, and various attempts have been made to achieve these objectives. One crucial means for achieving these objectives is an improvement in a printing section which mechanically requires large space for installation, and thus printing apparatus, having a structure in which a platen for enabling printing on a tape in cooperation with a printing head is provided in a tape cartridge, have been proposed. During printing, the printing head nips a printing tape in cooperation with the platen. The above-described structure enables the tape cartridge to be readily replaced with a new one only by retracting the printing head. Tape cartridges which accommodate various types of tapes which differ in material, width and color and ink ribbons used for printing on such tapes are commercially available. For use, the user selects a tape cartridge which accommodates the type of tape suited to the user's object from among various types of tape cartridges, and mounts it on the printing apparatus. However, such tape cartridges which accommodate different types of tapes therein have a problem in that excellent printing may not be obtained depending on some combinations of printing apparatus and types of tapes. That is, a desired contact state between the printing head and the tape cannot be obtained when a tape cartridge which accommodates, for example, a thick tape is mounted in a printing apparatus originally designed to employ a thin tape or conversely when a tape cartridge which accommodates a thin tape is mounted in a printing apparatus originally designed to employ a thick tape, thus making achievement of excellent printing impossible. To solve the above problem, it has been considered to provide in the printing apparatus a mechanism for adjusting the position of the printing head in accordance with the thickness of the tape. However, the use of this method makes the entire structure of the apparatus complicated. Further, in this method when the user mounts a tape cartridge on the printing apparatus, the user must check whether the adjusting mechanism of the printing apparatus is in a state corresponding to the thickness of the tape accommodated in the mounted tape cartridge, and, if the mechanism is not in that state, must operate the adjusting mechanism, making the use of such a printing apparatus troublesome. The above-described problems occur not only with respect to the thickness of tape accommodated in the tape cartridge but also regarding the width and hardness of the tape as well as regarding the width of an ink ribbon. The tape cartridges which accommodate different types of tapes also suffer from a problem involving smear of the tape with the ink of an ink ribbon, depending on some combinations of ink ribbons and platens accommodated in the tape cartridges. This problem also makes the provision of excellent printing impossible. When the tape cartridge is mounted in the printing apparatus, the tape and the ink ribbon are pressed against the platen by the printing head. If the width of the tape and ink ribbon is larger than the width of the printing head and if the platen is made of a relatively soft material, the platen is greatly deformed by the pressing of the printing head, thus firmly pressing the tape and ink ribbon against the edges of the end portions of the printing head. In a case of an ink ribbon of the type in which ink is attached to the tape when firmly pressed, the ink is undesirably attached to the tape when the tape and the ink ribbon are pressed against the edges of the end portions of the printing head. The document EP-A-0 593 269 discloses printing apparatus using a tape cartridge that includes a printing tape, an ink ribbon and a platen. The platen is a hollow member covered with a platen rubber. Different tape cartridges includes tapes of different widths and the width of the platen rubber is adapted to that of the tape. US-A-4,517,573 discloses a thermal ink transfer printing apparatus having a platen roller whose circumferential face is made from rubber having a hardness (JIS hardness) ranging from 25° to 40°. As described in this document, when rubber having a hardness of 55° is used and the thermal head is pressed with small force against the platen roller, only a linear contact is established between the recording sheet and the ink ribbon, resulting in inferior transfer-printing. In order to solve this problem and to allow the row of heating elements on the thermal head to uniformly press the recording sheet against the platen roller with the ink ribbon interposed, rubber having a hardness of 24°- 40° is employed for the platen roller, thus enabling all of dots to be finely transfer-printed and causing no inferior transfer-printing. JP-A-60-151077 discloses for a printing apparatus a platen which has a polygonal cross-sectional shape. Rubber surfaces differing in hardness within the range of 40° to 98° are provided on the peripheral surfaces. The platen can be manually rotated to select that one of the rubber surfaces whose hardness is best suited to the currently installed the kind of print head or the type of paper to print on. It is an object of the present invention is to provide a set of tape cartridges which can eliminate the above-described problems and ensure excellent printing regardless of the type of tape and ink ribbon. This object is achieved with a set of tape cartridges as claimed in claim 1 and a method of manufacturing them as claimed in claim 2. According to the present invention, the harder the printing tape, the softer the rubber provided on the surface of the platen. Accordingly, the pressed state of the printing tape pressed against the platen by the printing head can be made uniform by the platen regardless of the hardness of the printing tape. Consequently, excellent printing can be obtained regardless of the hardness of the printing tape. Fig. 1 is a plan view of a tape writer 1 in which tape cartridges according to the present invention can be mounted; Fig. 2 is a side elevational view of the tape writer 1 of Fig. 1; Fig. 3 is a plan view illustrating a tape cartridge 10 according to an embodiment of the present invention; Fig. 4 is a bottom view of the tape cartridge 10 of Fig. 3; Fig. 5 is an end view illustrating the tape cartridge 10 and taken in a direction indicated by arrows A-A of Fig. 3; Fig. 6 is a section taken along the line which passes the center of a tape cartridge 10a, the center of an ink ribbon core 22, the center of a ribbon take-up core 24 and the center of a platen 12; Fig. 7 is a view similar to Fig. 6, illustrating a tape cartridge 10b; Fig. 8 is an enlarged view illustrating a section of the printing apparatus in which a tape T and an ink ribbon R are held by the platen 12 and a printing head 60; Fig. 9 is a graphic representation showing the relation between the hardness of the tape T and the hardness of a platen rubber 14; Fig. 10 is a graphic representation showing the relation between the thickness of the tape T and the hardness of the platen rubber 14; Fig. 11 is a graphic representation showing the relation between the width of the tape T and the hardness of the platen rubber 14; Fig. 12 is an enlarged cross-sectional view of the platen rubber 14; Fig. 13 is a perspective view illustrating a structure for restricting free rotation of the ink ribbon core 22; Fig. 14 illustrates the tape T and the ink ribbon R which are in a state wherein printing can be performed thereon by the printing head 60; Fig. 15 is a perspective view of a cartridge mounting section 50A; Fig. 16 is a perspective view illustrating a gear train and a mechanism for moving the printing head 60 between a retracted position and a printing position; Fig. 17 is an exploded perspective view of the printing head 60; Fig. 18 is a block diagram of a structure controlled under a CPU 110; Fig. 19 illustrates a key array of an input section 50C; Fig. 20 illustrates a display section 50D; Fig. 21 is a flowchart showing an outline of the processing performed by the tape writer 1; Figs. 22 (a), 22(b), 22(c) and 22(d) illustrate adjustment of the hardness of the platen 12 by both an outer diameter of the shaft 13 and a thickness of the platen rubber 14; Fig. 23 is a cross-sectional view illustrating a state wherein an ink ribbon R having a width greater than the width of a heating member HT and less than the width of a head body 65 and the tape T are held by a platen 12G and the printing head 60; Fig. 24 is a cross-sectional view illustrating a state wherein the ink ribbon R and the tape T are held by a platen 12H having a width greater than the width of the heating member HT and less than the width of the head body 65 and the printing head 60; Fig. 25 is a cross-sectional view illustrating a state wherein the ink ribbon R and the tape T are held by a printing head 160 having members 165a provided at two end portions of a head body 165 and the platen 12; and Fig. 26 is a cross-sectional view illustrating a state wherein the ink ribbon R and the tape T are held by a printing head 160 in which corners ED of two end portions of a head body 165 are machined and the platen 12. To further clarify the structure and function of the present invention, a tape cartridge, which is a preferred embodiment of the present invention, and a tape writer for detachably incorporating the tape cartridge to conduct printing on the tape will now be described . Fig. 1 is a plan view illustrating a tape writer 1 which is in a state wherein a body cover 50K is opened. Fig. 2 is a right side view illustrating the tape writer 1 with the body cover 50K closed. Fig. 3 is a plan view illustrating assembly of a tape cartridge 10 which is to be mounted on the tape writer 1. In this embodiment, a cartridge for accommodating both an ink ribbon and a tape on which printing is conducted using the ink ribbon is employed. Thereinafter, the cartridge, which is not only a tape cartridge but also an ink ribbon cartridge, is called a tape cartridge. As shown in Fig. 1, the tape writer 1 includes a body case 50H for accommodating various parts, an input section 50C having 61 input keys, a body cover 50K which can be opened and closed, a display section 50D provided below the cover 50K in such a manner that the user can look at a string of characters or other data displayed thereon, a cartridge mounting section 50A provided at the left upper portion of the body in which a tape cartridge 10 is detachably mounted, and a power source switch 50J. The body cover 50K has a window 50L through which the user can confirm the mounting of the tape cartridge 10, and a window 50M through which the user can look at the display section 50D, as shown by alternate long and two short dashes line in Fig. 1. A transparent plastic plate member is fitted in each of the two windows 50L and 50M. Opening and closing of the body cover 50K are detected by an opening/closing detection switch 55 which is not shown in Fig. 1. When the tape writer 1 is to be used, the body cover 50K is opened first, and then a head moving lever 63C is turned counterclockwise as viewed in Fig. 1 by 90 degrees. Thereafter, the tape cartridge 10 is mounted in the cartridge mounting section 50A. In the state wherein the head moving lever 63C is turned, a printing head 60, which will be described later, is moved into a head case 60C to a retracted position so as to allow the tape cartridge 10 to be readily mounted in the cartridge mounting section 50A. Thereafter, the head moving lever 63C is turned clockwise to a position shown in Fig. 1. In that state, although the printing head 60 is located at a printable position, the head moving lever 63C obstructs removal of the tape cartridge 10. Thus, removal of the tape cartridge 10 is prohibited, thus preventing damage to the printing head 60 or tape cartridge 10. After the tape cartridge 10 has been mounted, the body cover 50K is closed. In a state wherein the head moving lever 63C is turned, i.e., the printing head 60 is retracted into the head case 60C, the head moving lever 63C prohibits closing of the body cover 50K, thus prohibiting a printing operation. After the body cover 50K has been closed, the printing apparatus is switched on by operation of the power source switch 50J. In that state, the user inputs characters to be printed from the input section 50C and performs Kanji and Kana conversion on the input character string if necessary. When the user instructs printing by operating a predetermined key, printing is performed on a tape T supplied by the tape cartridge 10 with a heat transfer type printer section 50B which will be described later. The tape T on which printing is performed is discharged from a tape outlet 10A provided on the left side of the tape writer 1. The tape T employed in this embodiment has a printing surface which assures excellent attachment of ink in heat transfer printing. A release tape is adhered to the sticky rear surface of the tape T. Thus, the user can paste the tape T on which characters or symbols are printed to a desired site by cutting the tape with a built-in cutter and by peeling the release tape off the rear surface thereof. Although not shown, a battery accommodating section is provided in the rear surface of the tape writer 1. The battery accommodating section is capable of accommodating six UM-3 dry cells as the power source of the entire apparatus. Power supply can also be obtained by connection of an AC adaptor (not shown) to a socket 50N provided on the right side of the apparatus body. The structure and function of the tape cartridge 10 will now be described with reference to Figs. 3, 4 and 5. The tape cartridge 10 is capable of accommodating a tape T which differs in thickness, width and material from the tapes accommodated in other tape cartridges 10. These tape cartridges 10 have a similar configuration. Regarding the shape and material of the tape T to be accommodated in the tape cartridge, there are two types of tape thicknesses, 100 µm and 200 µm, in this embodiment. With respect to the tape width, tapes of five widths, 6 mm, 9 mm, 12 mm, 18 mm and 24 mm, are available. As for the tape material, the embodiment offers four types of tapes, i.e., a tape having a printing surface made of polyester and coated with a release tape made of paper (hereinafter referred to as a "polyester (paper)" tape, a polyester (polyester) tape, a vinyl chloride (paper) tape and a paper (paper) tape. In the tape having a printing surface made of polyester or vinyl chloride (hereinafter referred to as "a plastic tape"), there are four types of colors for the printing surface, transparency, white, yellow and sky blue. In the tape having a printing surface made of paper (hereinafter referred to as a "paper tape"), the printing surface has three colors, white, yellow and sky blue. The ink ribbon R to be accommodated in the tape cartridge 10 together with the tape T has four colors, black, red, blue and green. Thus, in each of three types of plastic tapes, there are total of 160 different types (2 x 5 x 4 x 4) of tapes which differ from each other in the thickness, width and color of the tape and in the color of the ink ribbon R. There are 120 different types (2 x 5 x 1 x 3 x 4) of paper tapes which differ from each other in the thickness, width and color of the tape and in the color of the ink ribbon R. That is, a total of 600 types (3 x 160 + 120) of tapes are available in this embodiment. A list of such tape cartridges 10 is shown in Table 1. Type of tape cartridge Plastic tape Paper tape Material Polyester (paper) Polyester (polyester) Vinyl chloride (paper) Paper (paper) Thickness (µm) 100, 200 100, 200 Width (mm) 6, 9, 12, 18, 24 6, 9, 12, 18, 24 Color of tape Transparency, White, Yellow, Sky blue White, Yellow, Sky blue Color of ink ribbon Black, Red, Blue, Green Black, Red, Blue, Green The platen 12 employed for printing is a hollow cylindrical member. In order to assure excellent contact between the tapes T having different thicknesses, widths and materials and ink ribbons B and the printing head 60 and thereby obtain excellent printing, a platen rubber 14 corresponding to the type of tape T is fitted on the outer peripheral surface of the platen 12. The platen rubber 14 is made of silicon rubber. In this embodiment, a total of 32 types of platen rubbers 14 are available. That is, regarding the thickness of the platen rubber, there are two types, 1.9 mm and 2.0 mm, in response to the types of tape thicknesses. Regarding the width of the platen rubber, there are two types, 12 mm to be used for the tape widths of 6 mm, 9mm and 12 mm, and 18 mm to be used for the tape widths of 18 mm and 24 mm. Regarding the hardness of the platen rubber, three types of hardnesses, 60 degrees, 65 degrees and 70 degrees, are available in the platen rubber having a width of 12 mm. In the platen rubber width 18 mm, five types of platen rubber hardnesses, 40 degrees, 45 degrees, 50 degrees, 55 degrees and 60 degrees, are available. Regarding the surface roughness of the platen rubber 14, there are two types, a rough one (300 µm) and a smooth one (500 µm), in response to the materials of the release tape. The unit "degree" of the hardness of the platen rubber represents the hardness of rubber, measured by the rubber hardness meter conforming to JIS-K6301. The greater the numeral, the harder the rubber. The adjustment of the hardness of the platen rubber 14 is performed on the basis of the results of an actual printing test. A hardness which assures excellent printing quality and printing strength in an actual test is made an optimum hardness. The unit of the surface roughness of the platen rubber is µm (Note the term "surface roughness" as used in this text refers to the maximum height Rmax as defined in JIS-B0601). Table 2 is a list of platen rubbers 14 to be mounted in the tape cartridge. Type of platen rubber Width (mm) 12 18 Thickness (mm) 1.9, 2.0 1.9, 2.0 Hardness (degree) 60, 65, 70 40, 45, 50, 55, 60 Roughness (µm) 300, 500 300, 500 Figs. 6 and 7 illustrate examples of tape cartridges in which the width of the platen rubber is varied according to the tape width. Fig. 6 is a sectional view of a tape cartridge 10a in which a paper tape having a thickness of 100 µm and a width of 6 mm is accommodated, taken along a line which passes through the center of an ink ribbon core 22, the center of a ribbon take-up core 24 and the center of the platen 12. Fig. 7 is a view similar to Fig. 6 illustrating a tape cartridge 10b in which a paper tape having a thickness of 100 µm and a width of 24 mm is accommodated. To simplify illustration, the reference numerals in Fig. 7 are omitted. Further, in order to illustrate a mounting state of the tape cartridge on the tape writer 1, part of the printing head 60 is also shown in Figs. 6 and 7. As shown in Figs. 6 and 7, when a platen rubber 14 having a width corresponding to the tape width is used, the tape T can be conveyed in an excellent state. The reasons why the thickness of the platen rubber is varied according to the tape thickness are to allow the platen 12 and a tape guide pin 26 to reliably convey the tape T regardless of the thickness thereof and to allow the platen 12 and the printing head 60 to press and nip the tape T under a fixed pressure. Fig. 8 is an enlarged view illustrating a state wherein the tape T and the ink ribbon R are held by the platen 12 and the printing head 60. A solid line in Fig. 8 indicates a platen rubber 14A and the tape T having a thickness of 100 µm. A broken line indicates a platen rubber 14B and the tape T having a thickness of 200 µm. As shown in Figs. 6 and 7, when a platen rubber 14 having a thickness corresponding to the thickness of the tape is used, the gap between the platen 12 and the tape guide pin 26 can be made to correspond to the thickness of the tape T, thus enabling the tape T to be fed reliably. The gap between the platen 12 and the printing head 60 can also be made to correspond to the tape thickness T, thus enabling the tape T and the ink ribbon R to be pressed in an excellent state during printing. Thus, excellent printing can be achieved regardless of the thickness of the tape T. Table 3 shows an example of how to vary the hardness of the platen rubber 14 in response to changes in the hardness, thickness and width of the tape T. In the example shown in Table 3, there are a total of twelve different types of soft tapes T, that is, two types of materials, polyester (polyester) and paper (paper), two types of thicknesses, 100 µm and 200 µm, and three types of widths, 9 mm, 18 mm and 24 mm. Table 3 also lists a total of nine different types of hard tapes, i.e., three types of materials, paper (paper), polyester (paper and vinyl chloride (paper), three types of thicknesses, 100 µm for the paper (paper) tape, 200 µm for the polyester (paper) tape and 200 µm for the vinyl chloride (paper), and three types of widths, 9 mm, 18 mm and 24 mm. The column for the hardness of the platen rubber 14 shown in Table 3 indicates the hardness range which assures excellent printing relative to a corresponding tape T with the hardness value which assures the best printing in that range as a central value. As shown in Table 3, under a condition that the hardness and thickness of the tape T are the same, the wider the tape, the softer the platen rubber 14 in order to assure excellent printing on the tape T. Under a condition that the hardness and width of the tape T are the same, the thicker the tape, the softer the platen rubber 14. Under a condition that the thickness and width of the tape T are the same, the harder the tape, the softer the platen rubber 14. The pressing force of the printing head 60, obtained when the tape cartridge is mounted in the tape writer 1, is determined by a spring which presses the printing head 60 toward the platen and is fixed regardless of the width of the tape T. Thus, if a wide tape T is used, the pressing force of the printing head 60 per unit area is reduced, making a contact state between the printing head 60 and the tape T shifted from an excellent state and making excellent printing impossible. In order to compensate for this, a soft platen rubber 14 is employed to assure excellent contact state between the printing head 60 and the tape T, and the wider the tape T, the softer the platen rubber 14. The reason why a softer platen rubber 14 is employed as the thickness or hardness of the tape T increases is also to obtain an excellent contact state between the printing head 60 and the tape T, as in the case of the tape width. Figs. 9, 10 and 11 are respectively graphic representations showing the relations between the hardness, thickness and width of the tape T and the hardness of the platen rubber 14 which assures excellent printing. It is thus possible to obtain a platen rubber 14 having a hardness suited to the tape T having arbitrary properties from a quaternary map of relations between the hardness, thickness and width of the tape T and the hardness of the platen rubber 14 which assures excellent printing under various conditions. In this embodiment, when the tape T having a release tape made of paper is used, a platen rubber 14 having a smooth surface (500 µm) is used. When the release tape is made of polyester, a platen rubber 14 having a rough surface (300 µm) is used. The reason why a platen rubber 14 having a rough surface is used when the release tape is made of polyester is as follows: since the platen rubber 14 is made of silicon rubber, if the surface of the platen rubber 14 is smooth and if the tape cartridge 10 has been mounted in the tape writer 1 for a long time, the platen rubber 14 may lightly adhere to the release tape. When printing is performed in that adhered state, the tape T may not be discharged smoothly from the tape outlet 10A and jammed in the tape cartridge 10. Hence, a platen rubber 14 having a rough surface is employed so as to prevent adherence of the platen rubber 14 to the release tape or so as to allow the adhered release tape to be readily peeled off the platen rubber 14. Thus, the surface roughness of the platen rubber 14 is determined by both the material and surface roughness of the release tape of the tape T. Fig. 12 is a section taken along the plane which lies along the axis of the platen rubber 14 having an outer diameter of 9 mm and a width of 12 mm. As shown in Fig. 2, the platen rubber 14 has a barrel shape whose central portion 14b has an outer diameter of 9.2 mm and whose two end portions 14a have an outer diameter of 9.0 mm. In a platen rubber 14 whose two end portions 14a have an outer diameter greater than the outer diameter of the central portion 14b, the conveyed tape T or the ink ribbon R may shift from the central portion 14b thereof to one of the end portions 14a, making stable convey impossible. Such a problem can be eliminated if the outer diameter of the central portion 14b is larger than the outer diameter of the two end portions 14a. Manufacture of a platen rubber 14 whose central portion 14b has the same outer diameter as the two end portions 14a may also be considered. However, it may result in the manufacture of a platen rubber whose central portion 14b has an outer diameter slightly smaller than that of the two end portions 14a due to variations in the manufactured products. Such a platen rubber 14 also suffers from the above-described problem. A platen rubber 14 having a barrel shape can also eliminate the problems caused by variations in the manufactured products. In this embodiment, the outer diameter of the central portion 14b of the platen rubber 14 is greater by 0.2 mm than the outer diameter of the two end portions 14a. It is desired that the outer diameter of the central portion 14b be larger than that of the two end portions 14a by 1 to 3 %. If the outer diameter of the central portion 14b is larger than that of the two end portions 14a by more than 3 %, the force with which the two end portions 14a presses the tape T against the printing head 60 becomes too small, generating printing failure, such as faint characters. A platen rubber 14 having a width of 18 mm also has the same barrel shape. The upper and lower end portions of the platen 12 on which the above-described platen rubber 14 is fitted have a diameter slightly smaller than that of the other portion of the platen 12. These small-diameter portions are loosely and pivotally fitted into engagement holes 16A and 18A formed in a ceiling wall 16 and a bottom wall 18 of the tape cartridge 10, respectively, whereby the platen 12 is made pivotal. The engagement holes 16A and 18A have a substantially elliptical form, as shown in Figs. 3 and 4. The platen 12 provided upright in the tape cartridge 10 in the manner described above can be mounted on and removed from a platen driving shaft provided in the tape writer 1. The platen driving shaft will be described later. In order to allow the rotational driving force of the platen driving shaft to be transmitted to the platen 12 in a state wherein the platen 12 is in engagement therewith, six engaging grooves 12A are formed on the inner peripheral surface of the hollow portion of the platen 12 equiangularly in the direction of the rotational axis of the platen, as shown in Figs. 4 and 6. In addition, the tape cartridge 10 has the tape core 20, the ink ribbon core 22 and the ribbon take-up core 24 raised thereon for compactly winding up and storing the elongate tape T and ink ribbon R. Further, the tape cartridge 10 is formed with an inserting hole 32 through which a printing head to be described later is inserted. A guide wall 34 is formed on the periphery of the inserting hole 32. The tape core 20 is formed as a hollow cylindrical reel having a relatively large diameter so that a tape T having a great length may be taken up and stored into a relatively small thickness. Accordingly, the angular speed of rotation of the tape core 20 in drawing out the tape T located on the outermost circumference (indicated by "a" in Fig.3) is not largely different from the angular speed of rotation of the tape core 20 when the tape T located on the innermost circumference (indicated by "b" in Fig.3) is drawn out at the same rate. Further, since the curvature at the time of winding up for storage is small, storing is possible without an excessive strain even if the material of the tape T is vulnerable to bending stress. As shown in Fig.5, the tape core 20 has a shaft hole 20B formed at the center thereof so as to be rotatably fitted onto a shaft body 18B which is raised from the bottom wall 18 of the tape cartridge 10. Circular thin films 20A are pasted to upper and lower ends axially of the tape core 20, their surface toward the tape T being formed as an adhesive layer. Each film 20A serves as a flange for the tape T. Since each has an adhesive layer on the side toward tape T, the butt ends of tape T are lightly adhered to the films 20A. Accordingly, even when the tape T is drawn out by a rotation of the platen 12 to cause a following rotation of the tape core 20, the tape T on the core will not be loosened. The tape T wound and stored around the tape core 20 reaches the platen 12 via a tape guide pin 26 which is raised from the bottom wall 18 of the tape cartridge 10 and is drawn to the outside from the tape outlet 10A of the tape cartridge 10. A guide portion 10B is formed in a predetermined length at the portion of the tape outlet 10A along the transporting direction of tape T. In the state where the tape cartridge 10 is mounted on the cartridge mounting section 50A, the printing head 60 is located in the inserting hole 32. In this state, the tape T is nipped between the printing head 60 and the platen 12, transportation of the tape T being effected by a rotation of the platen 12. At this time, since the thickness of the platen rubber 14 attached to the platen 12 corresponds to the thickness of tape T, the tape T is brought into the same contacting state, irrespective of its thickness, with the printing head 60 through the ink ribbon R. Since the engagement holes 16A, 18A into which the upper and lower end portions of the platen 12 are fitted are formed as having an elliptical cross section as already described, the platen 12 may be moved along the longitudinal axes of the engagement holes 16A, 18A when the tape cartridge 10 exists by itself as a single unit. Accordingly, if an attempt is made to pushed the tape T into the tape cartridge 10 from the outside of the tape cartridge 10, the platen 12 is moved along the transporting path of the tape T by the movement of the tape T. Upon the movement of the platen 12, the platen rubber 14 of the platen 12 abuts against the outer periphery of the tape guide pin 26 and nips the tape T between it and the tape guide pin 26. As a result, the tape T cannot be moved any more and the tape T will not be pushed into the tape cartridge 10. The ink ribbon core 22 is constructed by a smaller-diameter hollow cylindrical member as shown in Figs.6 and 7, the outer circumference of the upper and lower end portions thereof being slightly reduced in diameter. On the end surface of the reduced-diameter lower end portion, equidistant six grooves are formed in the axial direction thereof as shown in Figs.3 and 4, so as to constitute an engaging portion 22A. This reduced-diameter portion toward the lower end is loosely fitted into a circular fitting hole portion 18C formed on the bottom wall 18 of the tape cartridge 10. Further, an upper end hollow portion of the ink ribbon core 22 is loosely fitted onto a circular cylindrical guide projection 16C protruding from the ceiling wall 16 of the tape cartridge 10. Accordingly, in this state, the ink ribbon core 22 is held in a manner rotatable following a drawing out of the ink ribbon R. It should be noted that a circular ring washer 23 is placed as shown in Fig.13 between a lid body forming the ceiling wall 16 of the tape cartridge 10 and the ink ribbon core 22. A free rotation of the ink ribbon core 22 is regulated as the ink ribbon core 22 is pressed toward the bottom wall 18 by a deformation of the circular ring washer 23. Further, as shown in Figs.3 and 4, a slender and generally L-shaped engaging piece 18D is formed on the bottom wall 18 of the tape cartridge 10 in the vicinity of the bottom portions of the ink ribbon core 22 and the ribbon take-up core 24 which will be described later. The engaging piece 18D is formed by boring through a portion of the bottom wall 18 (hatch portion X as shown in Fig.3) of the tape cartridge 10. Accordingly, the terminal end portion of the engaging piece 18D is movable along the plane of the bottom wall 18 about the base end portion 18E which is continued from the bottom wall 18 by means of the elasticity of the member constituting the bottom wall 18. In the state where no force is acting upon the engaging piece 18D, since the movable end portion thereof is positioned within the outer circumference of the fitting hole portion 18C, it engages one of the six engaging portions 22A formed on an end portion of the ink ribbon core 22 which is loosely fitted into the fitting hole portion 18C as described above, preventing rotation of the ink ribbon core 22. The ink ribbon R to be supplied as wound and stored around the ink ribbon core 22 is laid upon the above described tape T and reaches the platen 12 as guided by a ribbon guide roller 30. Further, it reaches the ribbon take-up core 24 via a guide wall 34 formed on a peripheral surface of the inserting hole 32 through which the printing head enters. The pulled around state of the ink ribbon R in the unused state of the tape cartridge 10, i.e., when only the starting end of the ink ribbon R is wound around the ribbon take-up core 24 is indicated by "c" in Fig.3, while the state at the time when all the ink ribbon has been taken up to the ribbon take-up core 24 is indicated by "d". As shown, the ribbon take-up core 24 is constituted by a hollow circular cylindrical member of substantially the same type as the ink ribbon core 22. Further, the circumferences of the upper and lower end portions thereof are also slightly reduced in diameter in a similar manner as the ink ribbon core 22. Six engaging portions 24A are indented at equal intervals on an end surface of the reduced-diameter lower end portion. On the other hand, six engaging stripes 24B are equidistantly formed on the ribbon take-up core 24 in the axial direction on the inner circumferential of its hollow portion, so that it may be driven to be rotated in a similar manner as the platen 12 by engaging a ribbon take-up core driving shaft to be described later provided on the tape writer 1. The ribbon take-up core 24 constructed in this manner is raised in a rotatable manner as loosely fitted at its reduced diameter portions formed at the upper and lower ends thereof into circular fitting hole portions 16G, 18G formed on the bottom wall 18 and the ceiling wall 16, respectively, of the tape cartridge 10. Further, in order to prevent an accidental rotation of the ribbon take-up core 24, a slender and generally L-shaped engaging piece 18H having an end portion thereof located within the outer circumference of the fitting hole portion 18G is formed in a similar manner as described above on the bottom wall 18 of the tape cartridge 10. That is, the engaging piece 18H is formed by boring through a portion of the bottom wall 18 (hatch portion Y in Fig.3) of the tape cartridge 10. In the state where the tape cartridge 10 stands alone, the end portion of the engaging piece 18H engages one of the six engaging portions 24A formed at an end portion of the ribbon take-up core 24, whereby a rotation of the ribbon take-up core 24 is prevented. Since the terminal ends of the engaging pieces 18D, 18H respectively face the engaging portions 22A, 24A in an oblique, as opposed to perpendicular, direction, it is possible for the ink ribbon core 22 and the ribbon take-up core 24 to be rotated counterclockwise. Such engagement between the engaging portion 22A of the ink ribbon core 22 and the engaging piece 18D and the engagement between the engaging portion 24A of the ribbon take-up core 24 and the engaging piece 18H are both released upon mounting of the tape cartridge 10 onto the cartridge mounting section 50A. The operation thereof will be described later together with the structure of the cartridge mounting section 50A. The ink ribbon R to be taken up by such ribbon take-up core 24 is a ribbon of the thermal transfer type, several kinds of dimension for its width being provided corresponding to the width of the tape T to be printed. In the present embodiment, the ink ribbon R is provided in three kinds: an ink ribbon of 12-mm wide as shown in Fig. 6 for the tape widths of 6, 9, 12 mm; an ink ribbon of 18-mm wide (not shown) for the tape width of 18 mm; and an ink ribbon of 24-mm wide as shown in Fig.7 for the tape width of 24 mm. If the ribbon width of the ink ribbon R is equal to the height of the tape cartridge 10 (see Fig.7), the ink ribbon R is guided by the ceiling wall 16 and the bottom wall 18 and no flange portion is formed on the outer circumference of the ribbon take-up core 24. For a tape cartridge 10 with a narrow ribbon width, however, a flange portion 24C suitable for the width of the wound and stored ink ribbon R is formed on the outer circumference of the ribbon take-up core 24 so that the ink ribbon R may be stably supplied to the platen 12. The ink ribbon R is guided by the flange portion 24C (see Fig.6). In the present embodiment, the platen rubbers 14 of the respective hardness are used to correspond to the three kinds of ink ribbons R differing in their width. An example of platen rubbers 14 of the hardness corresponding to the widths of the ink ribbon R is shown in Table 4. In Table 4, the thickness, width and material of the tape T are constant to facilitate understanding of the relation between the width of ink ribbon R and the hardness of platen rubber 14. That is, a paper tape (paper (paper)) having a thickness of 100 µm and a width of 18 mm and a plastic tape (polyester (paper)) having a thickness of 200 µm and a width of 18 mm are used as the tape T. For these tapes, the median and range are shown of the hardness of the platen rubber 14 capable of an excellent printing when the width of the ink ribbon R is 12 mm, 18 mm or 24 mm. Width of ink ribbon and hardness of platen rubber Material of Tape Thickness (µm) Width (mm) Width of ink ribbon (mm) 12 mm 18 mm 24 mm Paper (paper) 100 18 65±10 60±10 55±10 Polyester (paper) 100 18 55±10 50±10 45±10 As shown in Table 4, the larger the width of ink ribbon R, the softer the platen rubber 14. The reason for this is as follows. As shown in Fig.14 representing the state where printing by the printing head 60 is possible, the ink ribbon R is guided by the ribbon guide roller 30 from the ink ribbon core 22 of which the rotation is regulated by the circular ring washer 23 and is nipped between the platen 12 and the printing head 60 together with the tape T. It furthermore reaches the ribbon take-up core 24 via the guide wall 34 formed on the peripheral surface of the head case 60C. To obtain an excellent print by the ink ribbon R, a certain tension, i.e., a predetermined range of tensile force per unit width (for example, 1.1 gf/mm to 1.7 gf/mm (11 x 10 -3 N/mm to 17 x 10 -3 N/mm)) is required in the direction of its length. Such tensile force may be obtained by causing a frictional force which acts in the direction opposite to the rotation of the ink ribbon core 22 as the circular ring washer 23 in the form of a curved thin plate is pressed between the ink ribbon core 22 and the ceiling wall 16. Its magnitude may be adjusted by the degree of curving of the circular ring washer 23 or by the thickness of the circular ring washer 23. Since the ink ribbon R requires a predetermined tensile force per unit width, the tensile force is increased as the width of the ink ribbon R is increased. In the state where printing by the printing head 60 is possible, the printing head 60 pushes the ink ribbon R indicated by a broken line in the figure up to the position of the platen 12. At this time, since a force in the direction opposite to the direction for pressing the platen 12 (direction of the arrow as shown in the figure) due to the tensile force of the ink ribbon R acts upon the printing head 60, the pressing force against the platen 12 is reduced by an amount corresponding to such force. Since, as described, the circular ring washer 23 is adjusted so that the tensile force per unit width of the ink ribbon R falls in a predetermined range, the pressing force of the printing head 60 against the platen 12 is decreased as the width of ink ribbon R is increased. Accordingly, if the platen rubbers 14 of the same hardness are used for the ink ribbons R that are different in width, the extent of deformation of the platen rubber 14 is smaller as the width of ink ribbon R is larger, since the pressing force of the printing head 60 against the platen 12 is decreased as the width of ink ribbon R is increased. As a result, the position of balance between printing head 60 and platen 12 is moved toward the printing head 60, whereby transporting amount per unit time of the tape T by the platen 12 is increased and an excellent printing cannot be performed. Therefore, by using a softer platen rubber 14 as the width of ink ribbon R is increased, a constant level irrespective of the width of ink ribbon R is achieved for the amount of deformation of platen rubber 14 with respect to the pressing force of the printing head 60 toward the platen 12 which is smaller as the width of ink ribbon R is larger. The same position is thus maintained as the position of balance between the printing head 60 and the platen 12. As a result a uniform transporting amount of the tape T is obtained and an excellent printing becomes possible. In the present embodiment, 600 types of the tape cartridge 10 are resulted if all the combinations are counted based on the thickness, width and material of the stored tape T and colors of the ink ribbon R as described. Since the area which may be printed differs when the width of tape T is different, it becomes necessary to detect the width of a tape cartridge 10. In the tape cartridge 10 of the embodiment, three detecting holes 18Ka, 18Kb, 18Kc are provided on the bottom wall 18 of the cartridge to enable discrimination of each type of tape cartridge 10. That is, the detecting holes 18Ka, 18Kb, 18Kc are formed to have different depth corresponding to the width of the wound and stored tape T. Accordingly, by providing a sensor for detecting depth of the detecting holes 18K, a maximum of seven different tape widths of the cartridge 10 may be discriminated from each another. The tape cartridge 10 as described in detail above is mounted onto the cartridge mounting section 50A of the tape writer 1. Each of the mechanical constructional portions of the tape writer 1 will be described below in a sequential order. Fig.15 is perspective view schematically illustrating the construction in the vicinity of the cartridge mounting section 50A, being a perspective view where a cutter button 96 for cutting a printed tape T is represented by a broken line. Fig.16 is a perspective view where the construction of certain portions of the drive mechanism 50P for driving such as the platen 12 by the power of a stepping motor 80 is represented by the solid line while a turning frame 62 which is turned about the head rotary shaft 64 by a turning operation of the head moving lever 63C is represented by the broken line. The cartridge mounting section 50A is disposed at the back side of the input section 50C on the left side of the display section 50D, i.e., the back side toward the left of the body of the tape writer 1. As shown in Fig.15, it is formed as a mounting space suitable for the shape of the above described tape cartridge 10. Raised in this mounting space are the shafts for engaging the respective hollow portions of the ribbon take-up core 24 and platen 12, and the printing head 60. Further, a base board 61 is attached by means of screw to the lower portion of the cartridge mounting section 50A. Disposed on the base board 61 are the drive mechanism 50P as shown in Fig.16 for transmitting rotation of the stepping motor 80 to such as the platen 12 and the tape cutter 90 as shown in Fig.15. However, in its normal state, the base board 61 is partitioned by the case of the cartridge mounting section 50A and such as the drive mechanism 50P will not be directly viewed by merely opening the body cover 50K. Fig.16 is an illustration where the case is removed and the drive mechanism 50P is depicted. Further, in Fig.16, represented by the broken line are the turning frame 62 and the cam member 63A for moving the head body 65 to its printing position or retracted position in accordance with an operation of the head moving lever 63C. Mounting or replacing of the tape cartridge 10 at the cartridge mounting section 50A is performed by opening the body cover 50K. Engagement between the body cover 50K and the body is released when a slide button 52 (see Fig.1) provided in front of the cartridge mounting section 50A is slid to the right. The body cover 50K may be opened as it is turned about a cover hinge 54 at the rear portion of the body. As already described, for engaging the ink ribbon core 22 and ribbon take-up core 24 to stop their rotation, the engaging pieces 18D, 18H are provided on the bottom wall 18 of the tape cartridge 11 to be mounted on the cartridge mounting section 50A. The engaging pieces 18D, 18H are formed by boring through certain portions (hatch portions X and Y as shown in Fig.3) of the bottom wall 18. Two wedge-like abutting projections 70A, 70B are raised as shown in Fig.15 on the portions of the cartridge mounting section 50A corresponding to the positions at substantially the centers of the hatch portion X and hatch portion Y, respectively. Accordingly, when the tape cartridge 10 is mounted on the cartridge mounting section 50A, the abutting projections 70A, 70B are fitted into the hatch X and hatch Y so that it presses the engaging pieces 18D, 18H toward the direction moving away from the end portions of the ink ribbon core 22 and the ribbon take-up core 24. Thereby, the respective engagement by engaging pieces 18D, 18H is released and the ink ribbon core 22 and ribbon take-up core 24 are brought into their rotatable state. A description will be given below of the transmission mechanism for transmitting rotation of the stepping motor 80 to such as a platen driving shaft 72 of the platen 12. As shown in Fig.16, a first gear 81 is attached to a rotating shaft 80A of the stepping motor 80, and a clutch arm 80B is fitted onto the rotating shaft 80A with a predetermined friction therebetween. A second gear 82 for meshing with the first gear 81 and a third gear 83 formed concentrically and integrally with the second gear 82 (indicated by a broken line in Fig.16 as it is hidden below the second gear 82) are attached to the clutch arm 80B, thereby forming a one way clutch with a fourth gear having a largest diameter which meshes with the third gear 83. That is, upon a rotation of the stepping motor 80 in the direction of arrow C as shown in the figure, the clutch arm 80B rotates in the direction of arrow C together with the second and third gears 82, 83 due to friction between the rotating shaft 80A and clutch arm 80B, so as to engage the fourth gear 84. As a result, rotation of the stepping motor 80 is transmitted to the fourth gear 84. Operation of the one way clutch will be described later. Upon rotation of the fourth gear 84, a fifth gear 85 formed concentrically and integrally with the fourth gear 84 is rotated in the same direction, the rotating force thereof being transmitted to a sixth gear 86 and a seventh gear 87. The sixth gear 86 is coupled at its rotating shaft to a take-up core driving shaft 74 and winds up the ink ribbon R upon rotation of the stepping motor 80. It should be noted that a rim 74A for actually driving the ribbon take-up core 24 is attached, with a predetermined friction, to the take-up core driving shaft 74. While, in normal state of operation, it is rotated following the rotation of the take-up core driving shaft 74 by the stepping motor 80, it is adapted to slip against a rotation of the take-up core driving shaft 74 when the ribbon take-up core 24 becomes unable to rotate, for example, because the ribbon take-up core 24 has reached the terminating end of the ribbon R. The rotation of the seventh gear 87 is transmitted to a ninth gear 89 which meshes with an eighth gear 88 formed concentrically and integrally with the seventh gear 87, so as to rotate the platen driving shaft 72. A rim 72A for fitting with the irregularity on the inner peripheral surface of the platen 12 is provided at the lower portion of the platen driving shaft 72. Accordingly, when the stepping motor 80 is rotated and its rotation is transmitted to the fourth gear 84 by means of the one way clutch, the platen driving shaft 72 and the take-up core driving shaft 74 are rotated at the end, so as to transport in accordance with a printing operation the tape T nipped between the platen rubber 14 provided on the outer circumference of the platen 12 and the head body 65 of the printing head 60 and at the same time to continuously take up the ink ribbon R in synchronization with the transporting of tape T. Projecting stripes 72B, 74B for engaging the engaging stripes formed on the inner peripheral surface of the hollows of the platen 12 and the ribbon take-up core 24 are formed equidistantly three each on the outer peripheral of the shafts of the platen driving shaft 72 and the take-up core driving shaft 74. By driving the platen driving shaft 72 and the take-up core driving shaft 74 at a predetermined rotating speed by means of the stepping motor 80, the tape T and ink ribbon R are drawn out from the tape core 20 and ink ribbon core 22 by a predetermined amount so as to be laid upon each other and are passed between the platen rubber 14 and printing head 60. At this time, by conducting electricity through the printing head 60 to control heating value by each dot, ink on the ink ribbon R may be thermally transferred to the tape T to effect printing onto the tape T. After the printing, only the tape T having a complete print thereon is discharged from the tape cartridge 10 and the ink ribbon R used for the printing is wound up around the ribbon take-up core 24 to be recovered. When the tape T is transported at the same time of printing in this manner, the tape T is discharged from the tape outlet 10A on the left side of the body. While such tape T should be severed by a cutting mechanism which will be described later, the user in some cases may try to draw out the tape T before the severance. However, if an attempt is made to forcibly draw the tape T out in the state where printing onto the tape T is possible, i.e., when the printing head 60 is pressing the tape T against the platen rubber 14, the platen driving shaft 72 also tends to rotate. Since the platen driving shaft 72 is largely geared down and since the stepping motor 80 possesses some degree of retaining torque, the platen driving shaft 72 cannot be rotated by the mechanism for normal operation. Further, naturally, the take-up core driving shaft 74 does not rotate, either. Accordingly, when the tape T is drawn out, the ink ribbon R is necessarily drawn out with the tape T. If, in such state, the tape T is severed using the cutting mechanism, the ink ribbon R will be also cut. This must be avoided. This embodiment overcomes the above-described problem by the use of the one-way clutch which is composed of the clutch arm 80B and the second to fourth gears 82 to 84. Namely, an attempt to extract the tape T causes the platen driving shaft 72 to rotate together with the platen 12. The rotation of the platen driving shaft 72 is transmitted to the fourth gear 84 through the gear train, so that the fourth gear 84 rotates counterclockwise. This also tends to rotate the third gear 83. However, since the shaft 80A of the stepping motor 80 does not rotate, the torque of the fourth gear 84 serves to push the clutch arm 80B carrying the third gear 83, thereby dismissing engagement between the third gear 83 and the fourth gear 84. As a consequence, the portion of the power train starting from the fourth gear and ending at the ninth gear 89 is disconnected from the stepping motor 80, so that the take-up core drive shaft 74 rotates as a result of rotation of the platen driving shaft 72 caused by the extraction of the tape T. Thus, the ink ribbon R also is taken up in accordance with the extraction of the tape T, without being extracted together with the tape T. It is to be understood that the driving of the stepping motor 80 causes the clutch arm 80B to be shifted to the same side as the fourth gear 4, whereby the third gear 83 is brought into engagement with the fourth gear 84. This movement of the clutch arm 80B is limited by the opening 80C which is provided in the base 61 and which receives the end of the clutch arm 80B. The tape T is discharged leftward from the tape cartridge 10 in accordance with the described printing operation. The tape after the printing thus discharged can easily be severed by a severing mechanism of the type shown in Fig. 15, as will be understood from the following description. A substantially-L-shaped rotatable tape cutter 90 and a spring (not shown) are fitted on a cutter support shaft projecting from the bottom of the cartridge mounting portion 50A. The resiliency of the spring produced a rotational biasing force which acts to bias the tape cutter 90 clockwise as indicated by a solid-line arrow D in Fig. 15, thereby holding the tape cutter 90 at the illustrated position. As a result of application of this rotational biasing force, the right end 90A of the cutter as viewed in the Figure contacts the reverse side of a cutter button 96 so as to push it upward. The right end 90A of the tape cutter 90 is bifurcated so as to define a valley which receives a pin 96A provided on the reverse side of the cutter button 96. Therefore, as the cutter button 96 is pressed downward, the left end 90B of the tape cutter 90 is moved downward. A movable blade 98 for cutting the tape T is provided on the left end portion 90B of the tape cutter 90. The movable blade 98 is spaced a predetermined angle from a stationary blade 91 which is provided on a side face of a cartridge mounting portion 50A. Therefore, pressing of the cutter button 96 causes the tape cutter 90 to rotate clockwise as viewed in the Figure against the force of the spring, whereby the tape T is cut by cooperation between the movable blade 98 and the stationary blade 91. A tape pressing member (not shown) is linked to the cutter button 96 so as to be moved in accordance with the operation of the cutter button 96, so as to fix the tape T in advance of the cutting of the tape T. This movement of the tape pressing member is detected by a detecting switch 99 (not shown) which generates a detection signal to be used in such a control as to prohibit printing when the tape T is being cut. A description will now be given of an operation in which a print head 60 for performing printing on the tape T in the tape cartridge 10 is moved between a printing position where it is adjacent to the platen driving shaft 72 and a retracted position where it is spaced from the platen driving shaft 72 so as to allow mounting/demounting of the tape cartridge 10 from the tape cartridge mounting portion 50A. As will be seen from Fig. 16, as well as from Fig. 17 which will be mentioned later, the printing head 60 has a head body 65 which is attached, through a heat radiating plate 65b, to an upright portion 62A of a rotary frame 62 journaled by a head rotary shaft 64 standing up from the base board 61. The rotary frame 62 which is indicated by broken line in Fig. 16 is strongly pulled by a spring (not shown) in the direction indicated by a broken-line arrow E and abuts a cam member 63A so as to be stably held by the latter. While the rotary frame 62 is stably held in this state, the upright portion 62A of the rotary frame 62 rotatable about the axis of the head rotary shaft 64 is positioned closest to the platen driving shaft 72 so that printing on the tape T can be executed by the print head 60 which is secured to the upright portion 62A. A rotary shaft 63Aa carrying the cam member 63A is connected to the lower end of a lever rotary shaft 63B which extends through a cylindrical member 50Aa protruding from the cartridge mounting portion 50A as shown in Fig. 15. A head shifting lever 63C is provided on an upper part of the lever rotary shaft 63B integrally therewith. Therefore, as the head shifting lever 63C is rotated 90° counterclockwise as indicated by the broken line F, the cam member 63A shown in Fig. 16 also is rotated 90° counterclockwise as indicated by the arrow C in Fig. 16. As a result, a recess 63Ab of the cam member 63A and a projection 62B of the rotary frame 62 are made to engage with each other, thereby being stabilized. In this state. the upright portion 62A of the rotary frame 62 is positioned farthest from the platen driving shaft 72, so that the print head 60 secured to the upright portion 62A is held at the retracted position so as to allow mounting/demounting of the tape cartridge 10. Fig. 17 is an exploded perspective view of the print head 60 rotatable between the print position and the retracted position as described above, illustrative of the detail of the construction of the print head 60. It is to be understood that the view presented in Fig. 17 is taken from the side reverse to the views of Figs. 15 and 16. As will be seen from Fig. 17, the printing head 60 has a head body 65 which is attached, through a heat radiating plate 65b, to an upright portion 62A of a rotary frame 62 journaled by a head rotary shaft 64 standing up from the base board 61. The head body 65 has a plurality of heat generating elements HT and, hence, produce heat at a large rate, so that it is attached to the heat radiating plate 65b. Since the head body 65 is carried by the rotary frame 62 so as to rotate, electrical connection to the head body 65 is achieved through a flexible cable 68. The heat radiating plate 65b is supported by the upright portion 62A of the rotary frame 62 at two points. One of the supporting points is presented by the head rotary shaft 64 which extends through a pair of angular holes 65ba formed in the heat radiating plate 65b. Each angular hole 65ba has a longer axis and a shorter axis, and is formed such that the direction of the shorter axis coincides with the direction of running of the tape. The length of the shorter axis is substantially equal to the diameter of the head rotary shaft 64, while the length of the longer axis is about twice as large that of the head rotary shaft 64. The other supporting point is provided by a pin 67b which is received in a rotary bearing 62Aa of the rotary frame 62 and in a rotary bearing 65bb of the heat radiating plate 65b so as to extend perpendicularly to the head rotary shaft 64. Consequently, the heat radiating plate 65b is precisely located in the tape running direction the shorter axes of the angular holes 65ba and is held rotatable in the direction of the width of the tape T about the longer axes of the angular holes 65ba and the pin 67b. Therefore, when the print head 60 is pushed towards the platen 12, the head body 65 is precisely located at the printing position where is faces the platen 12. When the tape T sandwiched between the platen 12 and the head body 65 is inclined in the direction of the width of the tape T, the heat generating elements HT can uniformly press the tape T against the platen 12, as the head body 65 is rotatable about the pin 67b following the inclination of the tape T. The thickness and the hardness of the platen rubber 14 on the platen 12 are determined to correspond to the hardness, thickness and the width of the tape T, so that the tape T can be pressed with a substantially uniform pressure distribution regardless of its hardness, thickness and width. A description will now be given of the details of the input section 50c, display section 50D and the printer section 50B which are incorporated in the tape writer 1. In order to facilitate understanding of the whole construction, a brief explanation will be given first of an electrical arrangement including the control circuit section F and other electrical parts. The control circuit section 50F which is built-up on a printed board is incorporated right below a main part cover 50K, together with the printer section 50B and so forth, Overall electrical arrangement is shown in Fig. 18. The control circuit section 50F of the tape writer includes a one-chip microcomputer integrally incorporating a ROM, RAM and an I/O (input/output) port, as well as a mask ROM 118. The control circuit section 50F also includes various circuits which provide interfaces through which the CPU 110 is connected to various sections such as the input section 50C, display section 50D, printer section 50B and so on. The CPU 110 is connected to the input section 50C, display section 50D and so forth, directly or via the interface circuits, so as to control these sections. As will be seen from Fig. 19, the input section 50C has 48 character input keys and 13 function keys. Thus, there are 60 keys in total in this section. The character input keys are arranged in accordance with JIS (Japanese Industrial Standards) form, thus presenting so-called full key arrangement. This key arrangement also includes a shift key which is known per se in order to avoid increase in the number of keys to be manipulated, as in the cases of ordinary word processors. The function keys are intended to enable, by single key operation, various functions which are used frequently, e.g., character entry, edition, printing and so forth, thus enhancing function of the tape writer 1. These keys are allocated to an 8 x 8 matrix. Namely, when viewed from the CPU 110, 16 input ports including the input ports PA1 to PA8 and PC1 to PC8 are grouped, and the 61 keys of the input section 50C are arranged on the points of intersection between these groups of input ports. Fig. 19 illustrates the detail of the key. A power source switch 50J is provided independently of the matrix key and is connected to a non-maskable interrupt MM1 of the CPU 110. The CPU 110, when the power source switch 50J is operated, starts a non-maskable interrupt so as to execute power on and off processings. A cover position detection switch 55 detects opening/closing motion of the main part cover 50K and delivers a detection output to the port PB5, so that the CPU 110 is capable of monitoring the state of the main part cover 50K through interruption. When the cover 50K in open state is detected during operation of the print head 60, the main display portion 50Da indicates occurrence of an error, and turns the power supply to the printer section 50B off. Ports PH, PM and PL of the CPU 110 are connected to a head rank discriminating portion 112. Considerable fluctuation is inevitable in the print head 60 due to errors incurred in the production process. The head 60 is sorted to one of ranks according to the result of measurement of the resistance value of the print head 60, and three jumper portions 112A, 112B and 112C of the head rank portion are set in accordance with the result of the measurement. Thus, the CPU 110 reads the state of the head rank discriminating portion 112 and performs correction of the driving time, i.e., heat generation, of the print head 60 in accordance with the result of the reading, thereby preventing any variation in the thickness or density of the print. The printing performed by the printer section 50B relies on thermal transfer printing technique, so that the thickness or density of the print depends not only on the energizing time but also on other factors such as ambient air temperature, driving voltage, and so forth. Variations in such factors are detected by the temperature detecting circuit 60A and the voltage detecting circuit 60B. These circuits 60A and 60B are integrally incorporated in the print head 60 and their outputs are connected to 2-channel analog-to-digital conversion input ports AD1 and AD2 of the CPU 110. The CPU 110 therefore can read digital signals corresponding to the voltages appearing at the ports AD1 and AD2, thereby effecting correction of the length of time over which the print head is energized. A discrimination switch 102 is connected to ports PB1 to PB3 of the CPU 110. As shown in Fig. 15, the discrimination switch 102 is disposed at right lower corner of the cartridge mounting portion 50A. This discrimination switch 102 integrally has three cartridge discrimination switches 102A, 102B and 102C which are received in three detection holes 18K formed in the tape cartridge 10. The length of projection of the cartridge discrimination switches 102A, 102B and 102C is determined in relation to the depth of the detection holes 18K formed in the tape cartridge 10. Thus, one of the cartridge discrimination switches 102 which has been received by the detection hole 18K having a comparatively small depth is stopped by the bottom of the hole 18K so as to be turned on, while a cartridge discrimination switch facing a comparatively deep detection hole 18K is received fully in the hole without being stopped, so as to be kept off. Therefore, by detecting the states of the three cartridge discrimination switches 102A, 102B and 102C, it is possible to identify the type of the tape cartridge 10 mounted in the cartridge mounting section 50A, i.e., the width of the tape T in the tape cartridge 10. Information concerning the width of the tape T is used in the control of the size of the font to be printed, as well as in a control of the printer section 50B which will be described later. A port PB7 of the CPU 110 receives a signal from a contact of a plug 50N which in turn receives a jack 115 so as to be supplied with D.C. power from an AC adapter 113. In this state, the supply of electrical power from the battery BT to the power supply portion 114 is interrupted due to an action of a break contact, thereby preventing wasteful use of the power from the battery BT. A signal from another contact in the plug 50N is received by the port PB7 of the CPU 110. The CPU 110 therefore can discriminate whether the main power of the tape writer 1 is derived from the AC adapter 113 or the battery BT, so as to conduct different types of control according to the type of the main power supply. In this embodiment, when the power is being supplied from the AC adapter 113, the printer section 50B is operative at the highest printing speed, whereas, when the power is from the battery BT, the speed of printing performed by the printer section 50B is lowered so as to suppress the peak of the electrical current supplied to the printing head 60, thus diminishing the consumption of the power from the battery BT. An 8-megabit mask ROM 118 connected to the data BUS stores three sets of characters of Mincho-type font, i.e., Japanese Kana, Kanji and special characters, having sizes of 16 x 16, 24 x 24 and 32 x 32. A 24-bit address BUS AD, 8-bit data BUS DA, a chip select signal CS and an output enable signal OE of the ROM 118 are connected to ports PD0 to PD33 of the CPU 110. These signals also are connected to external I/O connector 50Ea. Therefore, an extension section 50E mounted on the external I/O connector 50Ea is accessible as is the case of the mask ROM 118. The extension section 50E, which is directly connectable to the control circuit section 50F, provides a receptacle for a ROM pack or a RAM pack which is supplied as option external storage device. Insertion of such a ROM pack or RAM pack into the receptacle completes electrical connection of the control circuit section 50F to the external I/O connector section 50Ea, thereby enabling exchange of information between the ROM or RAM pack and the control circuit section 50F. The extension section may receive any of different ROM packs which contain various kinds of characters such as those for drawings, maps, chemistry and mathematics, and language fonts other than Japanese, as well as fonts such as Gothic, Mincho and so forth, so as to enable edition with a desired type of characters. Similarly, a writable RAM pack received in the extension section can store information in excess of that can be held by the RAM area in the tape writer, thus enabling formation of a library of a print character train or exchange of data between different units of the tape writer 1. The character dot data read from the mask ROM 108 or from the extension section 50E is input to an LCD controller 116A of the display control circuit 116, as ell as to the CPU 110. The display section 50D controlled by the CPU 110 through the display control circuit 116 is disposed beneath a transparent portion of the main part cover 50K, so as to be observed by the user through the transparent portion. The display section 50D has two types of electrode pattern arranged on a liquid crystal panel. As shown in Fig. 20, one of these two types of electrode patterns is a dot matrix pattern, while the other includes 28 electrode patterns of square, circular and other forms arranged to surround the dot matrix region. The region in which the electrodes constituting the dot matrix pattern are arranged is referred to as a main display portion 50Da which displays character images, while the region where the square and circular electrode patterns are formed is referred to as an indicator portion 50Db. The main display portion 50Da is used as a liquid crystal display panel capable of presenting a display of 16 dots high and 96 dots wide. In this embodiment, character fonts of 16 dot wide and 16 dot high are used in the character entry and edition, so that the main display portion can perform a single-line display having 6 characters. The display of characters may be done in various manners depending on the state in the editorial work, such as positive display, negative display or flickering display, so as to visually inform the state of processing which is being conducted in the tape writer 1. Since the main display portion 50Da is constituted by a dot matrix which enables free control of the content of the display, it is possible to display the instant print image when a layout key of the input section 50C shown in Fig. 19 is pressed. The printer section 50B of this tape writer 1 has mechanical components including the print head 60 and the stepping motor 80, and electrical components including a printer controller 120 and a motor driver 122 which control the mechanical components. The print head 60 is a thermal head having 64 heating points which are arrayed in a single vertical row at a pitch of 1/180 inch (ca. 140 µm), and is provided therein with the aforesaid temperature detecting circuit 60A for detecting the ambient air temperature and the voltage detecting circuit 60B for detecting the supplied voltage. The stepping motor 80 has a reduction gear train which is designed such that, when the tape thickness if 100 µm, the amount of feed of the tape is 1/360 inch (ca. 70 µm) per one step of the stepping motor 80. The arrangement is such that a motor drive signal corresponding to two steps of the stepping motor is supplied to the stepping motor 80 per one dot of print performed by the print head 60. Thus, the printer section 50B performs printing not only in the tape width direction but also in the longitudinal direction of the same. The printing in the longitudinal direction i performed at pitch of 180 dots/inch (ca. 71 dots/cm). When a tape of 200 µm thick is used, the thickness of the platen rubber 14 also is changed, so that the amount of feed of the tape per one step of the stepping motor 80 is changed. More specifically, the amount of feed of the tape per one step of the stepping motor 80 increases 2 % when the outside diameter of the platen 12 is 9 mm. Therefore, no practical problem takes place even when the tape feed rate is not controlled in accordance with the tape thickness. The detecting switch 99 mentioned before is connected in a common line which interconnects the CPU 110 to the printer controller 120 and the motor driver 122. The detecting switch 99, which is intended to detect the state of use of the severing mechanism, operates to terminate the operation of the printer section 50B without delay whenever it detects that the severing mechanism is going to start during printing. However, since the delivery of signals from the CPU 110 to the printer controller 120 and the motor driver 122 is continued, the printing is restarted when the operation of the severing mechanism is ceased. The tape writer 1 includes, besides various components described, a power supply portion 114 which provides a stable 5 V power for backup and for logic circuits from the battery BT, by an RCC system which makes use of an IC and a transformer. A port PB4 of the CPU 110 is used for the purpose of controlling the voltage from the power supply portion 114. The internal ROM of the CPU 110 controlling the above-described peripheral circuits stores various programs for executing the above-described operations. The internal RAM of the CPU 110 has a portion which serves as a system preservation area to be used for the purpose of execution of the programs stored in the internal ROM. Other portions of the internal RAM are available for use as user's areas such as a text area for character editorial work and file area for string the texts. A brief explanation will now be given of a processing performed by the tape writer 1 in accordance with this embodiment. Fig. 21 is a flow chart showing a portion of the processing routine to be performed by the tape writer 1. This tape writer 1 has various operation modes. Pressing of specific function keys in the input section 50C triggers various modes such as a line number appointing mode, layout display mode and so forth, as will be described later. When keys corresponding to characters are pressed while there is no designation of a mode, character data to be finally printed are entered. As this processing routine is started, discrimination or identification of the processing mode is conducted in Step S200. When no mode has been appointed, the CPU determines that the present mode is the character input mode, so that entry of the print data is executed in Step S210. Entry of the character data for alphanumeric characters is implemented by directly delivering the character data input through the keys to a print data buffer. Entry of Japanese Kana and Kanji is done by delivering Kana characters input through the input section 50C to the print data buffer after Kana/Kanji conversion. The print data buffer has a capacity large enough to store 125 characters at the maximum, so that an overflow processing is conducted in Step S220 when character data has been input in excess of this capacity. More specifically, the overflow processing is an operation to cut any portion of the character train beyond 125 characters, when the character train to be finally entered has been determined through the Kana/Kanji conversion, in the case where input data has been added to a character train. The overflow processing also deletes characters beyond 125 characters, when the total number of characters exceeds 125 when input data is inserted to an intermediate portion of the train of characters which have been inserted. After such an overflow processing, a processing is executed to display the finally determined character train on the display section 50D, in Step S230. A routine (not shown) is conducted as a part of the character displaying processing (S 230), in which, by making use of the print data in the print data buffer, the indicating elements "t" of the "line number" in the indicator portion 50Db, corresponding to the number of lines of the print data, are lit on and, at the same time, the indicator element "t" corresponding to the line where the cursor is located, is made to flicker. Then, the print data on the line under the editorial work is displayed by the dot matrix of the main display portion 50Da. As a result of this processing, the user can acquire information such as the total number of lines of the print data which is being edited, as well as the line on which the cursor is located, by observing the "line number" indication in the indicator portion 50Db. After finishing this displaying processing in Step S230, the process proceeds to "NEXT", thus completing this main processing routine. A description will now be given of the printing mode. When the printing mode is appointed, Step S280 is executed in which the detection signal from the cartridge discrimination switch 102 is read, followed by execution of Step S290 which performs a processing in which the width of the tape T now on the tape writer is determined based on the result of the detection by the cartridge discrimination switch S102 and in which the dot pattern of each line is developed by making reference to a font map stored in the internal ROM, based on the result of the determination of the tape width and the size of each character train. When the print font to be used in printing of each line is determined, print fonts corresponding to the character code of the character train to be printed are successively read from the mask ROM 118 and are developed into dot patterns to be printed. This operation is referred to as dot pattern developing processing (Step S290). Subsequently to the development of the dot pattern, the process proceeds to Step S300 which performs a printing processing. In this processing, the developed dot patterns are cut into vertical dot lines so as to form 64-bit serial data which is transferred to the printer section. Basic modes of use and operation of the tape writer 1 of this embodiment have been described. The tape writer 1 also have various other modes of use, although description of such modes is omitted. As will be understood from the foregoing description, the tape cartridge 10 of the illustrated embodiment offers the following remarkable advantage in that, by virtue of the use of the platen rubber 14 having the width and hardness determined in relation to the hardness, thickness and width of the tape T accommodated in the tape cartridge, it is possible to obtain good printing quality by the tape writer 1 devoid of any adjusting mechanism which would compensate for any variation of the hardness and width of the tape T resulting from the use of different types of tape cartridge having different hardness, thickness and width of the tape T accommodated therein. Namely, in each tape cartridge, the platen rubber 14 has hardness which is determined in relation to the hardness of the tape in the same cartridge, so that the tape T and the ink ribbon R can be nipped between the platen 12 and the printing head 60 with a moderate pressure suitable for the printing, regardless of the hardness of the tape T. When the platen rubber 14 has thickness and hardness which are determined in relation to the thickness of the tape T in the same cartridge, the tape T can be fed without fail by the functioning of the platen 12 and the tape guide pin 26, and the tape T together with the ink ribbon R can be nipped between the platen 12 and the printing head 60 with a moderate pressure suitable for the printing, regardless of the thickness of the tape T. When the platen rubber 14 has width and hardness which are determined in relation to the width of the tape T in the same cartridge, printing over the entire area of the tape T is made possible and the tape T together with the ink ribbon R can be nipped between the platen 12 and the printing head 60 with a moderate pressure suitable for the printing. It is therefore not necessary for the tape writer 1 to have any means of compensation for variation in the hardness and thickness of the tape T. At the same time, the user is relieved from burden of complicated work which otherwise is necessary for administrating tape cartridges of different tape types and for adjusting the tape writer 1 to adapt it to different types of tapes. When the surface roughness of the platen rubber 14 is selected corresponding to that of the release tape of the tape T, the release tape can be held in good condition of contact with the platen 12, so as to ensure safe feeding of the tape T. For the same reason, adhesion of the release tape to the platen rubber 14 can be avoided even when the tape cartridge 10 is held on the tape writer 1 for a long time. Furthermore, since the platen rubber 14 has a barrel-like shape, any tendency for the tape T or the ribbon R towards the ceiling wall 16 or the bottom wall 18 is suppressed, thus ensuring good quality of the printing. Furthermore, the position where the balance between the printing head 60 and the platen 12 is fixed so as to ensure a constant rate of feed of the tape T, thanks to the use of the platen rubber 14 which has a hardness determined in relation to the width of the ink ribbon R. Thus, the described embodiment enables use of different types of tape T without requiring changing of the tape writer 1, by virtue of the fact that the width and the hardness of the platen rubber are determined in consideration of the hardness, thickness and the width of the tape T, as well as the width of the ink ribbon R. This widens the selection of the tape T, thus promoting development of new types of tape cartridge. In the illustrated embodiments, the platen rubber 14 is barrel-shaped, so that the feed of the tape T or the ink ribbon R can be performed while centering the tape T or the ribbon R at the center 14b of the platen rubber 14. It is therefore possible to avoid problems such as deviation of the tape ribbon T or the ink ribbon R to one end of the platen rubber and twining of a side portion of the tape T or the ink ribbon R, so that the printing can be performed under good condition. The barrel-like shape of the platen rubber 14 also offers an advantage over the case where the central portion 154b of the platen rubber 14 has an outside diameter equal to that of both axial ends 14a of the same, in that the problem encountered when the central portion 14b happens to have a smaller outside diameter than both ends of the same, even when the tolerance for the fabrication of the platen rubber 14 is increased, i.e., even when the requirement for the precision is less severe. This facilitates production of the platen rubber 14 and offers increased yield of the platen rubber 14. Since the width of the tape T accommodated in the tape cartridge 10 is expressed in terms of combination of the depths of the three detecting holes 18Ka, 18Kb and 18Kc formed in the bottom wall 18, the tape writer 1 can automatically recognize the width of the tape in the tape cartridge 10, based on 3-bit information derived from the discrimination switch 102 capable of sensing the type of combination of the depths of these detection holes. In the illustrated embodiments, the reduction gear train of the tape writer 1 is so designed as to provide a tape feed rate of 1/360 inch (ca. 70 µm) per one step of the stepping motor 80 when the tape thickness of 10 µm, with 2 % variation for greater tape thickness of 200 µm. This, however, is only illustrative and an arrangement can also be used suitably in which part of the reduction gear train is mounted on the tape cartridge and such part of the reduction gear train is designed specifically for each type of the tape cartridge in relation to the thickness of the tape T accommodated therein, so that the above-mentioned tape feed rate of 1/360 inch (ca. 70 µm) can be obtained constantly on all types of the tape cartridges. When this arrangement is adopted, it is possible to perform printing without variation in the tape feed rate, regardless of variation in the thickness of the tape T, by a tape writer which does not have any mechanism for effecting compensation for the variation in the tape thickness. In the embodiment described hereinbefore, the hardness of the platen rubber 14 is varied in relation to the hardness, thickness and the width of the tape T to provide the described advantages. The same advantages can be enjoyed also when the hardness of the whole platen is varied, through suitable selection of the outside diameter of the shaft 13 of the platen 12 and the thickness of the platen rubber 14, instead of varying the thickness of the platen rubber 14 alone, as will be understood from the following description. Figs. 22(a) and 22(b) show a platen 12C having a shaft 13C of a comparatively small outside diameter and a platen rubber 14C of a comparatively large thickness, as viewed in section taken along a plane perpendicular to the axis and in section taken along the axis, respectively. Similarly, Figs. 22(c) and 22(d) show a platen 12D having a shaft 13D of a comparatively large outside diameter and a platen rubber 14D of a comparatively small thickness, as viewed in section taken along a plane perpendicular to the axis and in section taken along the axis, respectively. Thus, the platen 12C is composed mainly of the shaft 13C of a comparatively small outside diameter and a platen rubber 14C of a comparatively large thickness and provided on the shaft 13C, while the platen 12D is composed mainly of the shaft 13D of a comparatively large outside diameter and a platen rubber 14D of a comparatively small thickness and provided on the shaft 13D. The outside diameter of the platen rubber 14C of the platen 12C and the outside diameter of the platen rubber 13D of the platen 12D are equal to each other, and are made of the same silicone rubber, i.e., have the same level of hardness. Elastic materials such as a rubber exhibit characteristics which follow Hooke's law (F = kx). The elasticity constant k is proportional to the area of a cross-section perpendicular to the direction in which a force acts on the elastic member and is in inverse proportion to the length of the elastic member as measured in the direction of action of the force. Therefore, when both the platen 12C and the platen 12D are subjected to the same level of pressure exerted by the printing head 60, the platen 12C exhibits a greater deformation that the platen 12D. That is, the whole platen 12C is softer than the whole platen 12D. It is therefore possible to obtain a platen having the desired level of hardness without changing the platen outside diameter, by successively changing the outside diameter of the shaft 13 and the thickness of the platen rubber 14, Platens 12 having different levels of hardness are thus obtainable. By using these platens in relation to the hardness, thickness and the width of the tapes T, it is possible to achieve the same effects as those enjoyed in the foregoing description in which platen rubbers 14 of different levels of hardness are used. The described arrangement in which the hardness of the platen 12 is adjusted by selection of the outside diameter of the shaft 13 and the thickness of the platen rubber 14 offers an advantage in that the platen rubbers 14 of different platens can be produced from the same material, thus eliminating the laborious work which otherwise would be required to adjust the rubber material composition for developing different levels of hardness of the rubber itself. For the same reason, it is possible to reduce undesirable variation of the hardness among the formed platen rubbers 14. In the embodiment described before, the hardness of the platen rubber 14 is selected in relation to the hardness, thickness and width of the tape T. When the ink ribbon R uses a wax-type ink, for instance, there is a risk that the ink when strongly pressed is molten to be deposited to the tape T, so as to impair the quality of the print. Various different measures can be taken to eliminate the problem of tape contamination. For instance, Fig. 23 shows an arrangement in which the width of the ink ribbon R is determined to be not smaller than the width of the heat generating elements HT but not greater than the width of the head body 65, regardless of the width of the tape T. Fig. 24 shows another solution in which the width of the platen rubber 14H is determined to be not smaller than the width of the heat generating elements HT but not greater than the width of the head body 65, regardless of the width of the tape T. When the width of the ink ribbon R is determined to be not smaller than the width of the heat generating elements HT but not greater than the width of the head body 65 as shown in Fig. 23, the ink ribbon R together with the tape T is never pressed against the edges ED of the head body 65, even when the tape T is strongly pressed against the edges ED of the head body 65, because the width of the ink ribbon R is smaller than that of the head body 65. Similarly, in the arrangement shown in Fig. 24 in which the width of the platen rubber 14H is determined to be not smaller than the width of the heat generating elements HT but not greater than the width of the head body 65 regardless of the width of the tape T, the problem of contamination of the tape T with the ink cannot occur because the tape T and the ink ribbon R are not pressed against the edges ED of the head body 65. The arrangement shown in Figs. 25 and 26 also are effective in preventing the above-described problem of contamination of the tape T. Fig. 25 shows another arrangement in which members 165a are provided on both end portions of the surface of the head body 165 of the printing head 160 facing the platen, so as to smooth the above-mentioned surface of the head body 165 facing the platen. Fig. 26 shows an arrangement in which the edge portions ED of the head body 265 of the print head 260 are smoothly curved. The member 165a used in the arrangement shown in Fig. 25 may be of any suitable material such as a glaze of a glassy material forming the surface of the heat-generating elements HT. The member 165a, when formed by the glaze of a glassy material, may be fabricated integrally with the heat-generating elements HT or may be made separately therefrom. The arrangement using the members 165a as shown in Fig. 25 and the arrangement in which the edges ED of the head body 265 are smoothly curved reduce the load per unit area of the tape T and the ink ribbon R under pressure to such a level as will not cause the deposition of the ink from the ink ribbon R to the tape T, thus preventing the problem of contamination of the tape T. In the embodiment described before, softer platen rubber 14 is used when the wider ink ribbon R is used. Since the requirement is to fix the position of the balance between the platen rubber 14 and the printing head 60, an arrangement also may effectively be used in which the diameter of the platen 12 is selected to be smaller when a wider ink ribbon R is used. This can be implemented by reducing the thickness of the platen rubber 14 of the platen 12 when the wider ink ribbon R is used. In this case, the hardness of the platen rubber 14 is maintained constant regardless of the width of the ink ribbon R. This arrangement allows the platen rubbers 14 of different platens 12 to be formed from the same material, thus eliminating the necessity for laborious work of delicate adjustment of the rubber composition for realizing the desired hardness level of the rubber itself, while avoiding variation in hardness among the platen rubbers of different platens. An arrangement also can suitably be used in which the hardness and the thickness of the platen rubber 14 are determined in relation to the width of the ink ribbon R. Namely, this arrangement is a combination of the arrangement in which the hardness of the platen rubber 14 is reduced when the ink ribbon width increases and the arrangement in which the outside diameter of the platen 12 is reduced in accordance with an increase in the width of the ink ribbon R. Namely, it is not essential that only one of two measures, i.e., softening of the platen rubber and reduction in the platen diameter, is selectively used, and combined use of these two measures provide an appreciable effect adapting to variation in the width of the ink ribbon R. Although embodiments or different forms of the invention have been described, it is to be understood that these embodiments or forms are only illustrative and various changes and modifications may be imparted thereto without departing from the scope of the present invention as defined in the claims. For instance, although in the foregoing description the tape T accommodated in the tape cartridge has an adhesive layer on its reverse side, various other types of tape can satisfactorily be used, such as a tape to be lined with an adhesive tape, a laminate type tape having a transparent sheet protecting the print surface, a transfer type tape carrying a transferable ink for printing. It is also to be noted that the tape cartridge may not contain an ink ribbon, although the ink ribbons are accommodated in the ink cartridges of the described embodiments. In the set of tape cartridges provided according to the present invention, the harder the printing tape, the softer the rubber provided on the surface of the platen. Accordingly, the pressed state of the printing tape pressed against the platen by the printing head can be made uniform regardless of the hardness of the printing tape. Consequently, excellent printing can be obtained regardless of the hardness of the printing tape. As a result, it is not necessary for the user to manage complicated tape cartridges by himself or herself to cope with printing tapes having different hardnesses. Further, adjustment of the printing apparatus is not necessary.

Claims: A set of tape cartridges (10) including a plurality of tape cartridges each for use in a printing apparatus and accommodating therein a printing tape (T), an ink ribbon (R) to be used for printing on said printing tape, and a platen (12) for backing said printing tape during printing in a printing apparatus, said platen having a platen rubber (14) on its surface, characterized in that said plurality of tape cartridges differ from one another with respect to both the hardness of the respective platen rubber (14) and the hardness of the respective printing tape (T), wherein the hardness of the platen rubbers (14) and that of the printing tapes (T) are in a proportional relationship to each other such that the hardness of the platen rubber (14) of a first one of said tape cartridges is greater than the hardness of the platen rubber (14) of a second one of said tape cartridges, while the hardness of the printing tape (T) of said first tape cartridge is smaller than the hardness of the printing tape of said second tape cartridge. A method of manufacturing tape cartridges (10) for use in a printing apparatus wherein each tape cartridge accommodates therein a printing tape (T), an ink ribbon (R) to be used for printing on said printing tape, and a platen (12) for backing said printing tape during printing in a printing apparatus, said platen having a platen rubber (14) on its surface, characterized by manufacturing a plurality of said tape cartridges differing in the hardness of the respective printing tape (T) and selecting the hardness of the respective platen rubber (14) for each tape cartridge depending on the hardness of the respective printing tape (T) in accordance with a proportional relationship between the two hardnesses such that the hardness of the platen rubber (14) of a first tape cartridge, whose printing tape has a hardness smaller than that of the tape of a second tape cartridge, is selected to be greater than the hardness of the platen rubber (14) of said second tape cartridges.

Inventors: INAKOSHI DAISUKE, MATSUHASHI KUNIHIKO, SODEYAMA HIDEO, INAKOSHI, DAISUKE, MATSUHASHI, KUNIHIKO, SODEYAMA, HIDEO, INAKOSHI, DAISUKE, C/O SEIKO EPSON CORP., MATSUHASHI, KUNIHIKO, C/O SEIKO EPSON CORP., SODEYAMA, HIDEO, C/O SEIKO EPSON CORP.
Applicants: KING JIM CO LTD, SEIKO EPSON CORP, KING JIM CO., LTD., SEIKO EPSON CORPORATION
Application year: 1995
Main classification: B41J11
IPC codes: B41J32, B41J17, B65H19, B41J33, B41J2, B41J29, B41J15, B41J3, B41J11