DE2221705A1 - Character generator for the graphic representation of characters with variable character-proportional spacing - Google Patents

Description

Boeblingen, April 25, 19 72 ker-wk

Applicant: International Business Machines

Corporation, Armonk, N.Y. 10504

Official File number: New registration

File number of the applicant: LE 970 021

Character generator for the graphic representation of characters with variable character-proportional spacing , ___

The invention relates to a character generator for the pictorial representation of characters in display fields with variable character-proportional ones Spacing between characters.

Such a character generator is for visual advance notification purposes Stored texts suitable for typewriter printing before printing.

The prior art includes US Pat. No. 3,248,705, According to the teaching of an operator, characters are displayed with uniform step spacings in order to make it clear how these characters will appear evenly spaced on an eventual printout.

The US patent application with the file number 15 791 of March 2, 1970 relates to an output display with proportional character spacing, with the help of which an operator can be made recognizable how the displayed characters are used in a printout spacing proportional to characters will appear.

Another American patent application with the file number 15 79 3, also dated March 2, 1970, deals with an issue in the case of the characters either with uniform or with

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proportional distances can be represented. The proportional one Character representation is used when an expression is to be created with character-proportional spacing or with different large intervals should be blocked; the display with evenly spaced intervals is selected if as the issuer Printer a typewriter with only uniform step intervals is used. In all cases considered, the operator will made recognizable how and with what spacing the characters will ultimately appear in a printout. the If necessary, the operator can still influence the printout exercise on the final printed image.

Numerous typewriters with proportional spacing are available for the creation of output texts. The spacers however, are different in the various machines given. This depends primarily on the used Basic distance steps from; while the one machine has a pitch step of about 0.35 mm = 1/72 inch, another has such a step of 0.42 mm = about 1/60 inch. Consequently are the different basic spacing steps for each Machines different. Furthermore, there are also compression compression options with various typewriters, whereby from A predetermined number is subtracted from the provided basic spacing steps in order to allow for the possibility of crowding of printed lines to offer.

In order to receive an advance notice of output to the various named In order to be able to adapt systems, it should also be possible to display a proportional spacing of an adapted type. It is it is desirable to have a character generator that is as simple as possible for reasons of economy for generating the various To be able to use fonts.

There are two different designs in the prior art of character generators for a character-proportional output display. A prior art device is a so-called monoscope for displaying proportional characters.

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Different character sets are possible for display. The cost of such a device is, however, a multi-cell one Advertisement with a variety of type images in the way. The other prior art device generated from matrix points composite typefaces. This principle is less expensive than the aforementioned monoscope; an extensive choice of available characters with versatile proportional weights however, it also keeps the cost high.

In order to reduce the effort, it should be possible to use the same matrix area of the character generator used to display the letters of the same meaning in different character sets. When using this principle, however, some characters cannot be clearly defined, since the scanning gaps required in each case for the characters of the various types of characters considered can be different. One possible solution to this problem would be to increase the number of scanning columns of the display device by a factor of 2. However, this is unfavorable with regard to the operating speed of the circuits used. Another possibility would be to generally add an additional spacing column to each character. However, this can disturb the spacing relationship within successive lines of text.

To the devices and methods according to the state of the art To avoid given disadvantages and on the other hand to enable economical devices for the accurate print preview, a Character generator are created, each of which adds an additional vertical scanning column in predetermined spans; in order to the definition of all characters of all intended character sets allows without changing the spacing of the characters to disturb in adjacent lines. The basic step value of the character of the character set which requires the most sample columns, is used to define the specified range. This ensures that each character is displayed within a Lines that may contain an additional scanning step requires an additional scanning port ready. There-

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at is with such additional sampling columns and corresponding Steps to use the same character generator to define the characters of different intended character sets possible.

The solution to this problem is characterized in claim 1. The subclaims indicate advantageous developments in this regard.

An embodiment of the invention is shown in the drawings and is described in more detail below.

Show it:

1 shows the block diagram of a character generator

for the representation with character-proportional or evenly stretched spaces and

Fig. 2 shows a corresponding representation with characters per

proportional steps.

Characters to be displayed line by line with the aid of a cathode ray tube 11 are held ready in a memory 13. The successive Characters of the lines to be output are transferred from memory 13 via an AND circuit 15 to a character register 17 given. This character register leaves a corresponding input address arrive at the character generator decoder 19, which in turn scans the characters into a column register 21 feeds. The information held in columns in the column register 21 is read by a serializer 23 serialized. Its output signal is transmitted via a display amplifier 25 of the cathode ray tube 11 is supplied.

The character entered in the character register 17 becomes at the same time fed to a step decoder 31 as an address. This determines for the "eichen iUc" contained in the character register 17 according to the selected character set relevant basic scanning

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ORIGINAL INSPECTED

step count. According to the number of basic scanning steps thus determined a comparator 33 outputs an output signal when the last Sample column of a character is processed. With this comparator output signal becomes a memory address counter 35 and the already mentioned AND circuit 15 is applied and the next one Characters transferred from memory 13 to character register 17.

As can be seen in FIG. 2, each character is constructed point by point from matrix elements which each correspond to a luminous point on the cathode ray tube. The character H as an example is serially displayed on the screen of the cathode ray tube according to a perpendicular scan of the elements of the character H. While the cathode ray travels over the left bar of the ^y character, the cathode ray is not scanned for ten sections in a row according to the ten hatched elements of the first character column. The beam then jumps back to the highest position of the character and scans the elements of the second column, corresponding to which only one is not scanned brightly, namely during the scanning of the fifth vertical character element. This is done up to and including the last rightmost sample column; during this last scanning column, the electron beam again does not remain lightly scanned and then moves on to scan the character B.

According to FIG. 1, a point clock generator 41 is triggered by an oscillator and periodically advances. Every single one Dot clock corresponds to a vertically scanned drawing element, with ten dot clocks each of the ten vertically one above the other Elements each correspond to a vertical scanning column of a character. During additional dot cycles, the Cathode ray in the starting position of the next vertical Sample column back. When the dot clock reaches its zero position, it indicates that the next vertical Column of a character can be scanned. This zero output

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signal of the dot clock generator 41 moves the column counter 43 each time do one more thing. An output signal from the column counter 4 3 energizes one of the inputs of the character generator decoder 19 and thus monitors the column-wise transfer of the character information to column register 21.

The previous description explains the units that are used for successive Scanning vertical columns to define the characters to be displayed are required. These units with With the exception of the step decoder 31 and the comparator 33 correspond to a conventional character generator as used for generation used by characters with normal spacing. The function of the step decoder 31 and the comparator 33 has already been indicated. The two of you together initiate the start of the display of the next character. These units are not required if all characters are to be displayed with even character spacing; every seichen is subject to the same number perpendicular scans. However, if a character-proportional representation is to be made, each represented must be terminated Become a character variant; the step decoder 31 and the comparator 33 are used for this purpose.

Suppose the typewriter used has a basic step spacing of 0.35 mm corresponding to 1/72 of an inch. The width of the used Type characters should vary between 4 units for the narrowest character and 9 units for the widest character. Of the The operating mode switch 51 provided is brought into its uppermost position A. With the switch in this position, a column-by-column Representation of the individual characters on the cathode ray tube generated in the same way as the characters in the considered Typewriter with a basic step spacing of 0.35 mm appear. That is, the relative distance between the optically represented characters corresponds to the relative spacing of the printed characters; the optically represented characters are present when viewed perpendicular to each other as well as the printed characters. With this position of the operating mode switch

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51 in its topmost position A is a 1: 1 relationship between are given to the scanning columns and the columns of characters displayed on the cathode ray tube 11.

When the narrowest character on typewriters with a basic step spacing of 0.35 mm occupies four basic spacing steps and thus also includes four scanning columns, this is easy to define. According to FIG. 2, four scanning columns are required for scanning the character t including an associated empty column for the character spacing between two characters. The small t as well as the letters I, f, j and 1 occupy this minimum of four scanning columns, three for the actual characters and one for the character spacing. But when a typewriter is operated, the extreme characters are those between three and eight basic abs common scriptures including used and the one larger If the basic step spacing is 0.35 mm, then difficulties arise. For example, the letter t would have four basic spacing steps occupy a basic step spacing of 0.35 mm and only three basic spacing steps if on the same typewriter should be written condensed. This makes it clear that the total number of sample columns must be increased if one Output display for condensed writing with a typewriter should be possible with a basic letter spacing of 0.35 mm.

When the mode switch 51 is placed in its second position B and a character display with a basic pitch greater than 0.35 mm is to take place, a control signal is applied to a provided expansion counter 53, the task of which is to add additional scanning gaps in a manner to be described to slide the individual characters. A second column counter 55 receives pulses via an AND circuit 57, which in turn is controlled by output signals from the expansion counter 53. This AND circuit 57 is connected via its other input to the l'lull-Sicinalausf'ancr dos Punkttaktaebers 41 and always sends a number signal to the second column counter 55 when fiiii iiull -. 'Jiqric'ij from Punl: ttaktr; ebcr Al in addition to the / iusciangssig-

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nal from the expansion counter 53 occurs. The stretch counter 5 3 gives an output signal as long as it does not go into its first counting position. Assume that the mode switch 51 is at a standstill in its second position. The stretch counter 53 then operates as a four-digit ring counter which advances by one with each zero pulse from the dot clock generator 41. When the strain counter is switched back to its first count position, no output is given to the AND circuit 57, and therefore the second column counter 55 also not with the zero signal from the dot clock move on.

It can be seen that the counts of the second column counter 55 of the respectively covered number of scanning columns counted in the first column counter 43 remains behind. this is related to the suppression of one count that takes place during position 1 of the expansion counter 53. Since the output counts of the second column counter 55 with the aid of the comparator 33 can be compared with the actually covered scanning columns to complete a character display, the first column counter 43 call up additional scanning columns and appear on the screen of the cathode ray tube 11. Because the output signal of the second column counter 55 is used to stop the generation of characters when the count value of the second column counter is equal to the value output by the step decoder · 31, the number of additional scanning column cycles per character becomes depend on the difference between the count values in the first and second column counter. These additional cycles determine the overall appearance of the individual characters. When the operating mode switch is in its second position B, an additional Sample column cycle added three real sample columns each.

It has already been indicated that the character t at a basic step spacing larger than 0.35 mm occupies three scanning columns and requires a fourth scanning cycle for the character spacing. The same character generator decoder 19 can be used to generate the character t both with a basic pitch of 0.35 mm as can also be used with a slightly larger step spacing.

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In Fig. 2, a line of five t is shown. For every t, let three basic spacing steps be assumed for an output display with a assigned slightly larger basic step spacing than 0.35 mm. For five such ts are required fifteen spacing steps on a printout page. An H with eight spacing steps and a B with seven spacing steps next to each other would also occupy fifteen spacing steps. Suppose the five would t printed on the first line and the letters BIB on the next line. The left edge of the first t should match the the left edge of the H and the right edge of the last t are aligned with the right edge of the B. It should now be explained that there is a maximum error of only one scanning column on the left edge and two scanning columns on the right edge of the Characters when using the character generator described.

As already mentioned, there are three sample columns each an additional cycle is added. Thus, a total of twenty scanning cycles are carried out for the representation of the five t. The character H takes eleven sampling cycles. The B occupies ten. Thus, to represent the two letters HB is a sum of twenty-one Scan cycles required, with an alignment error of only one scan cycle on the right edge. For this it should be noted that even longer lines will not cause a major misalignment because the additional columns in in each case evenly distributed over each displayed line. The mismatches are not cumulative and hold always within the specified limits.

In Fig. 1 it can be seen that with the mode switch in its uppermost position A for 0.35 mm basic step distance an inverted signal is given to the AND circuit 50. This inverted signal blocks the transmission of the zero signals from the dot clock 41 to the expansion counter 53. Furthermore, an operating mode signal is fed to the step decoder 31, which ensures that that decoder output signals between four and nine spacer elements are issued. Since the expansion counter 53 does not switch,

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it will never be able to be moved into its first counting position. Thus, any mull output will be from the dot clock 41 is fed to the second column counter 55 like the first column counter 43 without hindrance. So there is a 1: 1 relationship between sample gaps and step elements given. Thus, whenever the number of scanned, by means of the second column counter counted columns with the output signal from the step decoder 31 agrees, the comparator 33 provides an output signal for calling of the next character.

When the operating mode switch 51 is in its second position B, the four already mentioned counter positions of the expansion counter 53 are activated. With each zero signal before the dot clock generator 41 at the end of each scanning column, the expansion counter 53 is thus incremented by one. Once this counter has reached its first counting position, the output signal to the AND circuit 57 is interrupted and the second column counter 5 counts no further once with the zero signal from dot clock 41. Thus, a fourth column is added per scan of three columns. The first column counter 43 switches on unhindered, and the character generator decoder 19 continuously receives its identification signals that the next following scanning column must be processed in each case. If a character such as t is to be displayed with three step elements and this is the first character of a line, then the expansion counter 53 is moved to its counting position 2 with a line start signal. At the end of the first vertical scanning column of the t, the dot clock generator 41 emits a zero signal, which advances the first column counter 43 by one, which in turn addresses the second scanning column of the t in the character generator decoder 19. The second column counter 55 also advances by one The expansion counter 53 also advances from counting position 2 to counting position 3. Then the second sample column of the t is processed I. At the end of this second column, the first column counter 4 switches again and addresses the third sample column of the character in the character generator decoder 19. The second column counter

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also advances and indicates to the comparator that two columns have been processed. The expansion counter 53 now moves from the counting position 3 to 4. When the third scanning column is finished, the dot clock generator 41 switches the first column counter 43 to 4 and the expansion counter 53 from 4 to 1. Always when the expansion counter 53 is in its first position arrives, its output signal is interrupted to open the and circuit 57 and ensures that the second column counter 55 does not switch. Since from now on the count of the second column counter 55 no longer coincides with the value output by the step decoder 31, the first column counter 43 initiates an additional scanning cycle as it continues to count. When this cycle comes to an end, the dot clock generator 41 again emits a zero signal, switches the expansion counter 53 to 2 and now again allows both column counters 43 and 55 to increment by one. Only now is the count of the second column counter 55 equal to the value output by the step decoder 31. The comparator 33 emits its output signal, clears the two column counters 43 and 55 and at the same time gives an opening signal to the AND circuit 15 and a signal to the memory address counter 35 to initiate the display of the next character. It can e per line a maximum error of two step elements occur, which hardly disturbs.

When the mode switch 51 is placed in its third position C, the expansion counter 53 is only a three-stage counter effective. Before reaching its 1 position again, the counts Strain counters then only up to 3 each and causes the addition an additional scanning column for every two scanning columns to be displayed. The total amount of additional scan cycles per active sample gaps is thus higher than before; the displayed typeface on the cathode ray tube 11 thus appears accordingly more stretched.

An even further stretch is achieved when the mode switch 51 is brought into its fourth position D. The expansion counter 53 only works as a two-digit counter. It will

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then an additional scanning cycle is added for each active scanning column.

It was explained how with the character generator described a relatively simple proportional adjustment of the optically represented Typefaces to the really appearing printouts from typewriters with different or also variable Basic step spacing is possible. As well as adding Scanning cycles for the purpose of stretching is possible, font compression can also be achieved by reducing the number of scanning cycles will. For this purpose, an additional operating mode switch position would then have to be provided and an operating mode signal derived therefrom are fed to the character generator decoder 19, due to this in characters with seven, eight or nine scanning columns one column is omitted.

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Claims (4)

P_jk T E H TA N "S P RU C II E 1. ; Character generator for the graphic representation of characters in - Display fields with variable character proportional Spaces between characters, characterized by the combination of the following features: a) Mode switch (51) for adaptation to one of several provided character sets with different character-proportional spacing per character. b) memory (13) for successively addressable characters for character display. c) step decoder (31), which depends on the position (B or A) of the operating mode switch (51) and of the character addressed in the memory (13) stands for determining successive scanning steps for the column-by-column scanning of the individually addressed characters of the selected character set. d) Character generator decoder (19) for successive column-by-column scanning signal generation for the respective XTd memory (13) addressed characters with a scanning step number dependent on the width of this character. e) Circuit arrangement (41-50-53-57-55) for adding empty scanning steps that expand the typeface the character representation depending on the position (B or A) of the operating mode switch (51) and from the column-wise advancing character scanning, with a selected character set of the first type per predetermined number of columns to be scanned each an additional empty scanning column due to an empty scanning step will be added, with a selected character set of the second type, however, no stretching empty scanning steps and columns to be added. _LE 970 021 209853/0987 f) Circuit arrangement (31-55-33) for terminating the scanning of an addressed character as a function of from the step decoder (31) and from the column-wise progressive scanning of this character and for addressing the next character if the number of decoded sample columns corresponds to in the step decoder (31), the required number of scanning columns of the displayed character matches, whereby additional empty sampling columns are not taken into account when comparing numbers. 2. Character generator according to claim 1, characterized in that the number of scanning columns provided per character is at least corresponds to the specified required number of scanning columns for the narrowest character of the first character set. 3. Character generator according to one of the preceding claims, characterized by further switch positions (C, D) of the Operating mode switch (51) for determining further specified Scanning column numbers, for each of which an expanding empty scanning column due to an additional empty scanning step is added when selecting a character set of a type different from the first and second. 4. Character generator according to one of the preceding claims, characterized by the addition of the expanding empty spacing column (s) per character at the end of the representation of the character concerned. ^{LE 97} O 021 209853/0987