Abstract:
A type-carrier disk with flexible tongues for a printing device includes a central part for fixing onto a selection shaft and a peripheral notched crown from which issue several flexible tongues each tongue ending with a base from which projects a corresponding character. For different fonts, in the corresponding disks, the characters present a similar angular position and the base of a similar character has the same dimension and form able to edge the envelope of the different fonts. A positioning wedge protrudes from the base of the character and cooperates with a V notched hammer of the machine. The tongues are regularly spaced following regular angular spaces and in the disk used for differential spacing characters, the axis of the characters are angularly shifted in relation to the wedges of the tongues in inverse ratio to the sizes of the character and to the spacing steps of which the disk is to be spaced after the printing of said characters.

Description:
This is a continuation of application Ser. No. 594,360 filed July 9, 1975, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a type-carrier disk with flexible tongues for a printing device and to a method for its manufacture. 
     A type-carrier disk with flexible tongues of the present type is already known, in which each character comes from a unified base for the various characters. Since the width of each base is chosen to accommodate the larger characters, the overall dimensions of the disk are bigger than the dimensions of disks having bases sized according to the width of the character carried thereon. This large size limits both the speed of character selection of the printing device and the viewing of the last characters printed. Moreover, a different mould is required for the manufacture of each different font. 
     This means the purchase of various fonts by the user rather expensive. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a type-carrier which can be produced at a relatively low cost and which permits high printing speeds. 
     Another object of the present invention is to provide for a typewriting machine operable with both differential and uniform spacing a type-carrier disk with flexible tongues carrying characters of variable widths designed for the best appearance with differential spacing and which can be used in alternative with a type-carrier disk with tongues carrying characters disposed for best appearance with uniform spacing. 
     The disk of the present invention includes a central part for fixing onto a selection shaft and a peripheral notched crown featuring a number of flexible tongues, each tongue ending in a base from which protrudes a corresponding character. 
     The present invention also provides that, for disks of different fonts, the same characters are present on each font at the same angular position and all bases carrying characters of various styles but of the same meaning or significance have the same size and shape on each of the different fonts the bases being nevertheless of substantially different shapes in order to locate the characters radially as near as possible to the selection shaft to thus construct a disk of minimum radius. 
     These and other characteristics of the invention will become clear in the following description of a preferred embodiment of execution, intended as an example only, thus by no means excluding other versions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a partial sectional view of a type-carrier disk according to the invention; 
     FIG. 2 shows a schematic view of a printing device, where the disk is mounted; 
     FIG. 3 shows a detail of FIG. 1; 
     FIG. 4 shows another detail of FIG. 1; 
     FIG. 5 shows a further detail of FIG. 1; 
     FIG. 6 shows a schematic view of some details of the invention; 
     FIG. 7 shows a schematic view of a detail for the manufacture of the disk in FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a type-carrier disk 20 made of high-resistance plastic material such as nylon reinforced with fiberglass, including a central part 21 which can be fixed in a way already known to the selection shaft 20 and a peripheral crown, radially notched, which defines a group of flexible tongues 22 angularly equidistant from each other. The tongues 22 end in a substantially enlarged part 23 which constitutes the base of the characters 24 which project from the base itself. A positioning wedge 27 protrudes from the face opposite the base 23 (FIG. 2). 
     The wedge 27 cooperates with a V-notch 28 of a hammer 29 align the stroke of the selected character 24 with the front platen 31. 
     In accordance with the invention, in order to reduce the size of the disk to the minimum, the bases 23 of the various characters 24 are brought as near as possible to the central part 21 and differ from each other so that the wider characters 24 are adjacent to the narrower characters so that they may also occupy a space wider than that of the characters 24 adjacent. 
     In order to reduce the cost of the disks 20, which is strictly linked to the cost of the moulds for their manufacture, the number of tongues 22 and therefore of bases 23 is greater than the number necessary to characters of a single language. 
     In particular the disk 20 has a hundred tongues, so that for example a single disk 20 may be used for printing devices having the capability of printing in several languages like Italian, French, French and German Switzerland, Luxembourg and Common Market/EEC 2 in which, of course, the keys for printing characters typical of a particular language cause different positioning of the disk. 
     A similar disk 20, with its various bases, is also used to carry the fonts designed for the same group of languages. To this end, the characters 24 of different styles and sizes but having the same meaning or significance are superimposed with one another on a single sheet (FIGS. 3, 4 and 5). The envelope described by these superimposed characters are used to determine the minimum size that the base 23 must have to accommodate the particular character in a number of different languages. 
     For the sake of clarity, FIGS. 3, 4 and 5 show only two possible different fonts indicated respectively by a solid and a dotted line. 
     In accordance with the present invention, there is provided a type-carrier disk 20 carrying characters or types 30 of varying widths designed for best appearance with differential spacing, and which can be used in alternative with a type-carrier disk carrying characters 24 designed for best appearance with uniform spacing in machines operable in modes for uniform spacing and differential spacing such as is shown in U.S. Pat. No. 2,581,200. 
     In the case of using differential spacing, after the printing of the individual character, the disk 20 (FIG. 2) and the corresponding hammer 29 are moved in relation to the platen 31 by unit spacings proportional to the width of the printed character the numerals 30. 
     The characters 30 optimized for differential spacing have generally various widths and in this manner the right margins of the printed characters are suitably spaced from the left margins of adjacent printed characters for the best appearance of the printed line. In particular, after the printing for differentiated fonts, of a character 30 which is narrow such as &#34;i&#34; (FIG. 6) the disk is moved on by three unit spaces, in a known way which is not illustrated in the drawings, but is known from U.S. Pat. No. 2,581,200. After printing respectively signs such as &#34;.&#34; (full stop/period) and &#34; &#34; (underline) the disk 20 is shifted by four or five unit spaces, while after the printing of wide characters such as &#34;m&#34;, the disk is shifted with respect to the platen by six unit spaces. 
     In accordance with the preferred form of execution of the invention, the axis of some characters 30 for the differentiated font is shifted in relation to a plane perpendicular to the platen 31 (FIG. 2) and which includes the edge 32 of the wedge 27. In particular, with reference to FIG. 6, only the widest character 30 is centered with respect to the wedge edge 32 with respect to the characters 30 which are narrower, they are shifted to the left, as illustrated depending upon the number of unit spaces they require for the best appearance if the printed line. 
     Thus space associated with the left edge of the individual character 30 is bound to the left by a similar space substantially equal to 1.5 unit spaces up to an alignment line displaced by three unit spaces constantly from edge 32 and represented by a line 33, while the spaces to the right, represented by an other alignment line 34, are respectively, shifted by one, two and three unit spaces in relation to the edge 32 with reference to the above cited examples. 
     The selection of characters 30 for the differentiated font will thus take place in the same way as for the characters 24 optimized for the uniform font, and the only difference in the printing device will be the different system of spacing, in itself known, which will enable the characters 30 to be spaced differently according to their width. The characters 30 for the differentiated font also contribute to the definition of the base 24. Some of these characters are indicated with a broken (- . - ) line in FIGS. 3, 4 and 5. The wide characters 30, in particular, are of a size comparable to the characters 24 for the normal font and are to a large extent aligned with them. 
     The narrower characters 30, on the other hand, are further apart compared with the corresponding characters 20 of the normal font, and are largely responsible for the size of the base 23. 
     Once the bases 23 have been described as above, the distribution of characters 24 or 30 in the various angle positions depends on the fact that characters 24 or 30, which take up more space, must be alternated with others which occupy less. Some characters are in fact incompatible because of interference which can arise between the corresponding bases 23. Within the limits of adjacent characters 24 or 30, the distribution of characters 24 or 30 on the disk 20 is optimized in order to obtain the maximum printing speed. 
     By using the disk 20 in a printing device of the type described in Ponzano U.S. Pat. No. 3,707,214, assigned to the Ing. C. Olivetti &amp; C., S.p.A., issued Dec. 26, 1972, the selection as regards the printing platen 31 (FIG. 2) of the character to be written 24 or 30 occurs through the rotation in two directions of the disk 20 in the shortest distance possible, starting from the position of the last character written. 
     For a particular language, through a statistical study of texts of a sufficient length, such as of 25,000, an examination is then made of the frequency with which the adjacent characters alternate with each other. On the basis of compatibility, the characters, in pairs, will be arranged on the disk 20 at angular distances closer together for the pairs which alternate more frequently, and further apart for those which alternate less often. Obviously the choice of the positions of characters 24 or 30 follows on from the solution of successive approximations, and compromise, and also depends on the degree of compatibility between the bases 23. On the basis of the previous considerations, and after indicating the angular position corresponding to the sign &#34; &#34; (underline) conventionally with &#34;1&#34;, the disk 20 corresponding to the Italian, French, Swiss French, German, Luxembourg and EEC2 languages, has the 100 characters 24 distributed as follows: 
     
         ______________________________________Pos. Char.    Pos. Char. Pos. Char. Pos. Char.______________________________________1    --      26     (     51         76   M2    ,       27     h     52   X     77   928             53    °                          78    44    ;       29     x     54   %     79   15    a       30     &#34;     55   |                                80   0(zero)6    s       31     a     56   Y     81   57    1       32     o     57   &amp;     82   38    r       33     V     58         83   89    e       34     S     59   μ  84   210   i       35     j     60   Z     85   611   t       36     G     61   U     86   R12   n       37     H     62   β                                87   713   9       38     ••                     63   *     88   L14   c       39     u     64   K     89   C15   v       40     1/2   65   =     9016   d       41     i     66   W     91   N17   :       42     Q     67   ?     92   P18   u       43     J     68   F     93   S19   &#39;       44     +     69   B     94   e20   e       45     k     70   D     95   g21   I       46     $     71   O     96   P22   f       47     /     72   A     97   b23   z       48     v     73   T     98   )24   q       49           74   E     99   m25   y       50     a     75   !     100  ·______________________________________ 
    
     Once the angular position of the characters 24 or 30 has been established a further step towards reducing the cost of the disk is made by using a single mould for all disks 20 in the group of languages and for the various series of fonts. This is achieved by constructing a mould 40 (FIG. 7), with a lower plate 41 and an upper plate 42 which copies the outline of the two faces of the disk 20, in negative. 
     In particular the plate 41 reproduces the face of the disk 20 on which the positioning wedges 27 are placed and since the external outline of the bases 23 is common to all disks 20 of said group of languages, this plate 41 may be directly used for all the disks 20 described earlier. 
     The upper part 42 which reproduces the face of the disk 20 on which the characters 24 or 30 are found, includes a central part, common to all disks 20, which copies the central part 21, the flexible blades 22 and a peripheral part consisting of a ring 43 in negative. This ring 43 is removably fixed, for example between the screws 44, and copies the bases 23 of the disk 20 on which the corresponding characters 24 of a font are engraved, in negative. 
     Thus, using the same mould 40 and changing only the type-carrier ring 43, all the type-carrier disks for different types of font and tongues in the same group in whatever known way, are obtained. 
     This radically reduces the cost of production for the equipping both of the entire mould section and the manufacture of the rings 43 in which the only variant is represented by different fonts of various characters 24.