DE2221705C3 - Character generator for displaying characters with variable character-proportional spacing - Google Patents

Description

7.5 The invention relates to a character generator for the graphic representation of characters in columns in display fields with variable character-proportional spaces between the characters according to the Preamble of claim 1.

Such a character generator is for the purpose of the optical advance display of stored texts before Suitable for typewriter printing.

The prior art includes US Pat. No. 3,248,705, which it teaches an operator Characters are displayed with uniform step spacing to show how these characters will appear evenly spaced on an eventual printout.

U.S. Patent 3,654,609 relates to an issue display with proportional character spacing, with the help of which an operator can recognize like the characters displayed in an expression with character-proportional spacing will appear.

U.S. Patent 3,648,271 is concerned with one Output display where characters can be spaced evenly or proportionally can be represented. Proportional character representation is used when a

so expression with spacing proportional to the character or with spacing of different sizes can be blocked target; the display with evenly spaced intervals is selected if a typewriter is used as the issuing printer is used with only uniform step spacing. In all cases considered, the operator made recognizable how and with what spacing the characters ultimately end up with you Printout will appear. The operator can, if necessary, before the printout

M) Effects on the final printed image exercise.

Finally, US Pat. No. 3,174,427 should also be mentioned in the present context. It The subject of this relatively early invention is a matrix printer with proportional Character distribution on the individual print lines. This matrix printer contains the following for this purpose Parts: a memory for consecutively

addressable characters; a step decoder, which depends on the character addressed in the memory is used to determine successive characters Scanning steps for the column-by-column scanning of the individual addressed Zexhen; a Character generator decoder for successive column-wise scanning signal generation for the respective Characters addressed in the memory with a scanning step number dependent on the width of this character; a circuit arrangement for terminating the scanning of an addressed character in dependence from the step decoder and from the column-wise progressive scanning of this character and to the Addressing of the next character if the number of decoded scanning columns corresponds to the im Step decoder matches the predetermined number of scanning columns of the displayed character. - With this one Matrix printer, however, is not yet a possibility to vary the proportional character spacing by means of an operating switch.

Compared to matrix printers, there are also numerous typewriters with proportional spacing available for the creation of output texts. The spacers, however, are different on the various given machines. This depends primarily on the basic spacing steps used; while one machine has a basic _{spacing step of approximately 0.35 mm = V 72} inches, another has such a step of 0.42 mm = approximately V hU inches. The various basic spacing steps are therefore different for the individual machines. Furthermore, various typewriters also offer compression compression options, a predetermined number being subtracted from the basic spacing steps provided in order to offer the possibility of crowding together printed lines.

In order to be able to adapt a previous output display to the various systems mentioned, 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 the To be able to use the different fonts.

There are two different types of character generators for one in the prior art Character-proportional output display. A device according to the state of the art is a so-called monoscope for displaying proportional characters.

Different character sets are possible for display. The cost of such a device is, however a multi-cell display with a variety of type images in the way. - The other facility after prior art produces typefaces composed of matrix points. This principle is less expensive than the aforementioned monoscope; an extensive selection of available However, standing signs with versatile proportional weights also keeps costs high.

In order to reduce the effort, each the same matrix area of the character generator used to display the letters with the same meaning different character sets can be used. However, when applying this principle some characters cannot be clearly defined because the required scanning gaps are at the considered characters of the different types of characters may be different. One possible solution this problem would be to increase the number of scanning columns of the display device by the Factor 2. However, this is unfavorable with regard to the operating speed of the circuits used. Another possibility would be the general addition of an additional spacing column each character. However, this can disturb the spacing relationship within successive lines of text will.

In order to avoid the disadvantages associated with devices and methods according to the state of the art and, on the other hand, to enable economical devices for the print-accurate advance display, a

is character generator to be created, each one additional vertical scanning columns are added in predefined ranges; this becomes the definition of all Allows characters of all the intended character sets without changing the spacing of the characters

2ü to disturb in adjacent lines. The basic step value of the character of the character set which most Sampling columns required is used to define the specified span. It is ensured that that each character within a displayed line, possibly an additional scanning step requires an additional sampling column. It is with such additional scanning columns and corresponding steps use the same character generator for definition the characters of different intended character sets possible.

The solution to this problem is characterized in claim 1. The subclaims give advantageous Refinements to this.

An embodiment of the invention is shown in the drawings and will be described in more detail below described. It shows

Fig. 1 shows the block diagram of a character generator for the representation with character-proportional or evenly stretched intervals, and

Fig. 2 shows a corresponding representation with character-proportional Steps.

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

The character entered in each case in the character register 17 is simultaneously used as the address of a step decoder 31 supplied. This is intended for the

fto chenregister 17 characters contained in the corresponding the number of basic scanning steps relevant to the selected character set. According to the number of basic scanning steps thus determined a comparator 33 outputs an output when the last sample column of a character is processed. With this comparator output signal, a memory address counter 35 and the already mentioned AND circuit 15 applied and thereby the next character from memory 13 in

the character register 17 transferred.

As can be seen in FIG. 2, each character is built up 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 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 is not scanned brightly only once, 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 steps periodically continue. Each individual dot clock corresponds to a vertically scanned drawing element, where ten dot clocks for the ten vertically superimposed elements each with a vertical scanning column correspond to a character. During additional dot cycles, the cathode ray returns to the Start position of the next vertical scanning column back. When the dot clock has its zero position reached, it indicates that the next vertical column of a character will be scanned can. This zero output signal of the dot clock 41 advances the column counter 43 by one at a time. An output of the column counter 43 is energized one of the inputs of the character generator decoder 19 and thus monitors the forwarding in columns the character information to the column register 21.

The previous description explains the units that are perpendicular to the successive scanning Columns to define the characters to be displayed are required. These units, with the exception of the Step decoder 31 and comparator 33 correspond to a conventional character generator like him is used to generate characters with normal spacing. The function of the step decoder 31 and the comparator 33 has already been indicated. The two of you together lead the beginning of the presentation of the next character. These units are not required if all characters are to be displayed with even character spacing; every character is subject to the same number of vertical scans. However, if a character proportional Representation is to take place, the termination of each represented character must be variant; to serve the step decoder 31 and the comparator 33.

Assume that the typewriter you are using has a basic step spacing of 0.35 mm, corresponding to V ₇₂ inches. The width of the type characters used should vary between 4 units for the narrowest character and 9 units for the widest character. The provided operating mode switch 51 is brought into its uppermost position A. With the switch in this position, a column-wise representation of the individual characters on the cathode ray tube is generated in the same way as the characters appear in the typewriter under consideration with a basic step spacing of 0.35 mm. That is, the relative distance between the optically represented characters corresponds to the relative distance between the printed characters; the optically represented characters are viewed perpendicularly to one another, as are the printed characters. With this position of the operating mode switch 51 in its uppermost position

K) Position A is a 1: 1 relationship between the scanning columns and the columns of the characters displayed on the cathode ray tube 11.

If the narrowest character on typewriters with a basic step spacing of 0.35 mm occupies four basic spacing steps and thus also comprises 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

2 «characters. The lower case I including a corresponding blank column for the character spacing between two characters. The small t as well as the letters /, /, j and / occupy this minimum of four scanning columns, three for the actual characters and one for the character spacing. However, if a typewriter is operated which uses between three and eight basic spacing steps as extreme characters and which has a basic step spacing greater than 0.35 mm, then difficulties arise. For example, the letter t would occupy four basic spacing steps with a basic step spacing ■ of 0.35 mm and only three basic spacing steps if the same typewriter is to be used for condensed writing. This makes it clear that the total number of scanning columns must be increased if an output display for compressed writing is to be possible with a typewriter with a basic step spacing of 0.35 mm.

When the mode switch 51 is placed in its second position B and a character display is to be made with a basic step spacing greater than 0.35 mm, a control signal is applied to a provided expansion counter 53, the task of which is to interpose additional scanning gaps in a manner to be described below 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 zero signal output of the dot clock generator 41 and always sends a count signal to the second column counter 55 when a zero signal from the dot clock generator 41 occurs in addition to the output signal from the stretch counter 53. The expansion counter 53 emits an output signal as long as it is not in its first counting position. Assume that the mode switch 51 is in its second position. The expansion counter 53 then works as a four-digit ring counter which advances by one with each zero pulse from the dot clock generator 41. When the expansion counter is switched back to its first counting position, no output signal is given to the AND circuit 57, and therefore the second column counter 55 will not advance with the zero signal from the dot clock either.

It can be seen that the counts of the second column counter 55 of the respectively covered,

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7 8

number counted in the first column counter 43 from the point clock 41 to the expansion counter 53. Des palpation remains opposite. This depends on further being an operating mode signal to the step decoder Suppression of one count, which is fed to 31, which ensures that the decoder while the position 1 of the expansion counter 53 is followed by output signals between four and nine distance values. Because the output counts of the second column 5 are output. Because the strain counter Counter 55 with the help of the comparator 33 does not switch to the effective 53, it is never in its first counter I Hch covered scanning columns can be moved into the termination position. So everyone becomes one Character representation are compared, that of the zero output from the dot clock 41 leaves the first Column counter 43 additional scanning columns prevented the second column counter 55 like that call and supplied to the first column counter 43 on the screen of the cathode ray tube. That’s a 11 appear. Because the output of the second 1: 1 relationship between sample columns and step column counter 55 given elements to stop the character generation. Thus, whenever the number is used when the count of the second column of the sampled, by means of the second column counter Counter with the output from the step decoder 31 55 counted columns with the output signal from If the value is the same, the number of additional decoders 31 will match, the comparator 33 key-column cycles per character from the difference of an output signal to call the next character Submit count values in the first and second column counter.

hang. These additional cycles determine when the mode switch 51 is in its

Overall appearance of the individual characters. If the second position is B , the four will already

the operating mode switch in its second position B 20 named counter digits of the expansion counter 53 ac-

is located, an additional scanning column is activated. With every zero signal from the dot clock generator 41

cycle added three real scanning columns. at the end of each sample column, the expansion

It has already been indicated that the character / at voltage counter 53 is thus advanced by one. if

a basic step spacing greater than 0.35 mm three of these counters enters its first counting position

Occupies scanning columns and for this purpose a fourth scanning 25 interrupts the output signal to the AND circuit 57

cycle required for the character spacing. The same, and the second column counter 55 counts once

The character generator decoder 19 cannot generate the with the zero signal from the dot clock generator 41

Character t both with a basic step spacing of further. Thus three columns per scan

0.35 mm as well as a fourth column added for a slightly larger step spacing. The first column counter

be used. 30 43 switches on unhindered, and the character gen-

In Fig. 2, a line of five / is shown. Each ratordecoder 19 continuously receives its t am three basic spacing steps in the case of an output identification signal, so that in each case the next following display has to be processed with a scanning column deviating from a slightly larger basic step. When stood assigned as 0.35mm. For five such ts , a character like the t with three step elements is to be displayed on a printout page with fifteen spacing steps and the first time is required. A H with eight distance steps and B surfaces is a line, then the Dehnungsmit is seven steps distance side by side would occupy counter with a start of line signal into its distance also fifteen steps 53rd Counted position 2 moved up. At the end of the first assume that the five ts would be printed on a first line of vertical scanning column of the t , the dot clock is printed and the letters HB on the next following 40 over 41 emit a zero signal, which the first column counter the line. The left edge of the first t should move one further with the 43, which in turn has the second abbreviated edge of the H and the right edge of the last key column of the t in the character generator decoder 19 t on top of the right edge of the B. addressed. The second column counter 55 also advances. It should now be explained that a maximum of one advances and the expansion counter 53 also advances by error of only one scanning column on the left edge 45 from counting position 2 to counting position 3. Then it becomes and of two Sample columns on the right edge of the line - the second sample column of the t is processed. At the end of the count when the character described is used, this second column switches the first column counter to the count generator. 43 again and addresses the third sampling

As already mentioned, there are three columns of each character in the character generator decoder 19.

An additional cycle is added to the scanning columns. 50 The second column counter 55 also advances

Thus, a total of twenty scanning cycles for the and indicates to the comparator that two columns

Representation of the five t carried out. The character H were processed. The expansion counter 53 is now moving

requires eleven sampling cycles. The B occupies ten. Thus from counting position 3 to 4. After completion of the

If the two letters HB is a third scanning column, the dot clock 41 is the

Total of twenty-one scanning cycles required, 55 first column counter 43 switch to 4 and the expansion

with an alignment error 53 from 4 to 1 on the right edge.

results from only one sampling cycle. For this purpose, the starting counter 53 has to run into its first position

note that even with longer lines there is no larger output signal to open the AND circuit

Alignment error will occur as the extra 57 is interrupted and ensures that the second column

Columns in each case evenly over each displayed counter 55 does not switch on. Since the count of the

put row to be distributed. The second column counter 55 is not yet in agreement with that of the

Errors are not cumulative and always match the value given in step decoder 31,

the specified limits. allows the first column counter 43 to continue counting

In FIG. 1 it can be seen that the Benen initiate additional scanning cycles. If this

mode switch in its uppermost position A for 65 cycle comes to an end, the dot clock generator 41 returns

0.35 ram the basic step distance, an inverted signal and a zero signal switches off the expansion counting

to AND circuit 50 is given. This inverts 53 to 2 and now again leaves both column

The controlled signal blocks the transmission of the zero signals. Just now

the count of the second column counter 55 is 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 outputs at the same time an opening signal to the AND circuit 15 and a signal to the memory address counter 35 for initiation the display of the next character. There can be a maximum error of two step elements per line occur, which hardly bothers.

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

Still further expansion 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. An additional scanning cycle is then added for each active scanning column.

It was explained how a relatively simple proportional adjustment can be made with the character generator described the optically represented typefaces to the really appearing printouts from typewriters with different or variable basic step spacing is possible. As well as that

ίο It is possible to add scanning cycles for the purpose of stretching, font compression can also be achieved by reducing the number of scanning cycles. These would have the character generator decoder are passed 19 then an additional mode switch position Al to be provided and any derivative mode signal on the basis of which one each column is omitted from signs with seven, eight or nine scanning columns. The same operating mode signal is also fed to the step decoder 31 in order to effect the output of an output value reduced by 1, so that the step decoder and column counter output values are equal to one step earlier.

1 sheet of drawings

Claims (4)

Patent claims: 1. Character generator for the graphic display of characters in columns in display fields with variable character-proportional spacing between characters and with a) a memory (13) for successively addressable characters for character display, b) a step decoder (31) which is addressed as a function of the address in the memory (13) Character stands for to determine the number of consecutive scanning steps the column-by-column scanning of the individual addressed characters, c) a character generator decoder (19) for successive column-wise generation of scanning signals for the character addressed in the memory (13) with a number of scanning steps that is dependent on the width of this character and d) a circuit arrangement (31-55-33) for ending the scanning of an addressed character depending on the step decoder (31) and the scanning of this character, which is also counted in columns, and for addressing the next character to be displayed if the number of scanning columns counted corresponds to that in Step decoder (31) matches the predetermined required number of scanning columns of the displayed character; the character generator is characterized by the combination of the following features:
c) an operating mode switch (51) for adapting the character-proportional spacing per character to a selectable, broadened character display type, with no additional expansion steps being generated for the characters displayed when the normal switch position (A) is selected; however, if a second switch position (B) is provided, additional expansion steps are added, and f) a circuit arrangement (41-50-53-57 -55) with an expansion counter (53) which, depending on the second operating mode (position B) selected by means of the operating mode switch (51), selects a blocking element (AND Circuit 57) is periodically blocked in front of the counter input (ZA) of a provided column counter (55) and thereby interrupts the continuous column counting by at least one counting step and delays the reaching of a column counter output value equal to the step decoder output value. 2. Character generator according to claim I, characterized by further switch positions (C, D) of the operating mode switch (51) for determining further, differently sized periodicities with to which stretching steps are added after active character scan and display columns. 3. Character generator according to one of the preceding claims, characterized in that a further operating mode switch position (AI) is is seen, in which the operating mode switch (51) is in its normal position (A ), in which the addition of expansion steps is omitted, and furthermore, via an additional contact of the operating mode switch (51), a control signal is sent to the character generator decoder (19) and the step decoder ( 31) is supplied, which suppresses the output of one column each from the character generator decoder (19) when displaying extremely long characters (M, W etc.) and at the same time lowers the step decoder output value by 1, so that the step decoder and column counter are equal Output values are reached one step earlier. 4. Character generator according to one of the preceding claims, characterized by the Addition of the stretching steps per character at the end of the representation of the relevant character.