Typewriting machines – Typing by other than type-face or type-die – Character formation by impact
Patent
1982-08-18
1984-08-28
Sewell, Paul T.
Typewriting machines
Typing by other than type-face or type-die
Character formation by impact
101 9305, 400121, B41J 312
Patent
active
044681410
DESCRIPTION:
BRIEF SUMMARY
The present invention pertains to a character generator of the kind having nine printing needles arranged in a column.
One application of a character generator is in matrix printers wherein it is used to generate the character information required for the printing needles of the printer to be able to build up different characters. Every such character consists of a number of dots in a N.times.M matrix. Normally, the height of the matrix is seven or nine dots while the width is determined by the horizontal resolution and may vary between 10 and 25 dots.
In the character generator there is stored either the specific character together with the interspace to the following character or just the character. In the latter case the interspace is formed by use of an algorithm. The character image is stored in a memory area, the start address of which is generated by a code, for instance the ASCII-code representing the said character. For example, the area may comprise 14 bytes of which 8 bytes represent the character and 6 bytes represent the interspace. In the example referred to the character requires seven printing needles. However, some characters require nine needles which causes problems because each byte contains at a maximum eight bits, each of which represent one needle. Hence, the memory area of the character must be enlarged and the easiest way is to reserve a separate byte for the ninth needle. Another possibility is to designate to one byte the ninth needle information relating to eight consecutive columns.
The following drawbacks are connected with the character generator disclosed above. narrow. However, this drawback may be eliminated if the interspace is generated by means of an algorithm. no information other than that no dot is to be printed in the specific column. printers designed for multi-pass printing, i.e. wherein the print head passes the same line more than once. Usually, during the second, third etc. passes the character generator contains up to 70-80% bytes comprising only noughts. are several methods available for storing the ninth needle information, all of them, however, having the disadvantage that all characters reserve memory area for the ninth needle, while just a few actually use the area reserved. Either these characters have to be treated separately or the memory area in the character generator must be determined by the character of the greatest length. order that not the character pitch but the character interspace, i.e. the distance between two consecutive characters, be invariable.
The object of the invention is to provide a character generator in which the drawbacks referred to above have been eliminated. The object is achieved in a character generator having the features included in the appending claims.
A more detailed description of the invention will be given below in connection with an embodiment with reference to the accompanying drawings in which
FIGS. 1 and 2 show the characters "P" and "g", respectively, printed by means of a dot-matrix print head.
FIG. 3 shows the information to be stored in the character generator to represent the character of FIG. 1. As FIG. 3,
FIG. 4 shows the information to represent the character of FIG. 2.
FIGS. 5 and 6 show the arrangement of the character information in a character generator according to the invention.
FIGS. 7 and 8 more in detail show the arrangement of the character information according to FIGS. 5 and 6 with reference to the character "P". In the same way,
FIGS. 9 and 10 show the character information of FIGS. 7 and 8 with reference to the character "g".
FIG. 11, finally, is a block diagram of the character generator.
The following description of the embodiment will be given with reference to the characters "P" and "g". In FIG. 1 the letter "P" is shown as printed by a dot-matrix print head comprising nine printing needles. The positions of the needles have been indicated by lines numbered 1-9 in a vertical row. Above the letter, the columns have been indicated in which the printing needles are activated. These columns
REFERENCES:
patent: 4187552 (1980-02-01), Verstegen
IBM Tech. Disc. Bulletin, by G. L. Douglas, vol. 19, No. 8, Jan. 1977, pp. 2851-2852, 400-121.
Facit Aktiebolag
Sewell Paul T.
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