DE2221705B2 - Character generator for displaying characters with variable character-proportional spacing - Google Patents

Description

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.

US Pat. No. 3,248,705 is to be mentioned in relation to the prior art, according to its teaching to 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.

US Pat. No. 3,648,271 is concerned with an output display in which characters optionally include can be displayed evenly or with proportional spacing. The proportional representation of characters 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 intervals. 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 Exert effects on the final printed image.

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 address in the memory Character stands for the determination of successive scanning steps for the column-wise scanning of the individual addressed characters; a character generator decoder for successive Column-by-column scanning signal generation for each character addressed in the memory with one of the Width of this character dependent number of sampling steps; circuitry for terminating the scan of an addressed character depending on the step decoder and the column-wise advancing character Scanning of this character and for addressing the next character if the Number of decoded scanning columns with the number of scanning columns specified in the step decoder displayed character matches. - With this matrix printer, however, there is still no possibility of varying the proportional character spacing provided by means of a mode 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 pitch step of about 0.35 mm = ₇₂ inches, another has one of 0.42 mm = about V ₆₀ 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 prior 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 many types of type images in the way. - The other facility after the prior art produces typefaces composed of matrix points. This principle is less expensive than the aforementioned monoscope; an extensive selection of available However, the standing characters with various proportional weights also keep the costs high.

In order to reduce the effort, the same matrix area of the character generator used should be used can be used to display the letters of the same meaning in different character sets can. When applying this principle, however, some characters cannot be clearly defined, because the scanning gaps required in each case for the characters of the various types of characters under consideration can be different. One possible solution to this problem would be to increase the scanning column zabJ of the display device by a factor of 2. However, this is unfavorable in terms of the speed of operation of the circuits used. Another possibility would be the basic one Adding an extra spacing column to each character. However, this can change the distance ratio are disturbed within consecutive lines of text.

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 Character generator are created, each of which has an additional vertical scanning column in predetermined Spans added; this enables the definition of all characters of all the intended character sets, without disturbing the spacing of the characters in adjacent lines. The basic step value the character of the character set, which requires the most sample columns, is used to define the specified range is used. This ensures that each character is displayed within a Line that may require an additional scanning step, an additional scanning column ready. It is used with such additional scanning gaps and corresponding grooves of the same character generator for the definition of 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

1 shows the block diagram of a two-dimensional generator for the display with character-proportional or evenly stretched spaces, and

2 shows a corresponding representation with steps proportional to characters.

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 given via an AND circuit 15 to a character register 17. This register of characters leaves a corresponding input address to the character generator decoder 19, which in turn then the Scanning characters are fed to a column register 21 in columns. The columns held ready in the column register 21 Information is serialized by a serializer 23. Whose output signal is The cathode ray tube 11 is supplied via a display amplifier 25.

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

wi chenregister 17 contained characters the corresponding the number of basic scanning steps relevant to the selected character set. According to the basic scanning number of steps thus determined a comparator 33 outputs an output signal when the last sample column of a character

<> 5 is processed. With this comparator output signal a memory address counter 35 and the already mentioned AND circuit 15 are 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 // ds 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 the light is not scanned 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 bars each of the ten vertically one above the other Elements each correspond to a vertical scanning column of a character. During additional The cathode ray returns point cycles to the start position of the next vertical scanning column return. When the dot clock reaches its zero position, it indicates that the next one vertical column of a character can be scanned. 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 uniform Character spacings are to be shown; each character is subject to the same number of verticals Scans. However, if a character-proportional representation is to take place, the termination of each shown characters are variant; the step decoder 31 and the comparator 33 are used for this.

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 displayed characters are viewed perpendicularly to one another, as are the printed characters. With the mode switch 51 in its uppermost position A in this position, there 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 in typewriters with a basic step spacing of 0.35 mm occupies many 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 characters. The small / including a corresponding empty column for the character spacing between two characters. The small t as well as the letters / /, / 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. Damii becomes apparent that the total number of scanning columns must be increased if an output display for condensed writing is to be possible with a typewriter with a basic pitch 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 add additional scanning columns in a manner to be described below Shift single characters zi. 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

so will. This AND circuit 57 is connected to the zero signal output of the dot clock generator via its other input 41 connected and then always allows a counting signal to reach the second column counter 55, wenr a zero signal from the dot clock generator 41 occurs in addition to the output signal from the expansion counter 53. Dei 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 works then 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 ai the AND circuit 57 is given, and therefore the second column counter 55 will not advance with the zero signal from the dot clock either.

It is easy to see that the counts de; second column counter 55 of each covered

in the first column counter 43 counted number of scanning columns 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 are compared with the actually covered scanning columns to complete a character display with the aid of the comparator 33, the first column counter 43 allows additional scanning columns to be called up and appear on the screen of the cathode ray tube II. Since 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 will depend on the difference between the count values in the first and second column counters. These additional cycles determine the overall appearance of each character. When the mode switch is in its second position B , an additional scan column cycle is added for every three real scan columns.

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

In Fig. 2, a line of five t is shown. Each t is assigned three basic distance steps in an output display with a basic step distance slightly larger than 0.35 mm. For five such ts , fifteen spacing steps are required 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 ts were printed on the first line and the letters HB on the next line. The left edge of the first I should line up with the left edge of the H and the right edge of the last t 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, an additional cycle is added to every three scanning columns. 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, a total of twenty-one scanning cycles is required to represent the two letters HB , with an alignment error of only one scanning cycle resulting on the right edge. It should be noted here that even with longer lines, no major alignment errors will occur, since the additional columns are in each case evenly distributed over each displayed line. The mismatch errors are not cumulative and are always within the specified limits.

In Fig. 1 it can be seen that with the operating mode switch in its uppermost position A for 0.35 mm basic step spacing, an inverted signal is sent to the AND circuit 50. This inverted signal blocks the transmission of the zero signals

from the dot clock generator 41 to the expansion counter 53. Furthermore, an operating mode signal is sent to the step decoder 31 supplied, which ensures that decoder output signals between four and nine spacer elements are issued. Since the expansion counter 53 does not switch, it is never in its first counting position can be moved into. Thus, any zero output from dot clock 41 is unimpeded the second column counter 55 as the first column counter 43 is supplied. That’s a 1: 1 relationship between sample gaps and step elements given. Thus, whenever the number of scanned, by means of the second column counter 55 counted columns coincides with the output signal from the step decoder 31, the comparator 33 emit an output signal to call 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 from the dot clock generator 41 at the end of each scanning column, the expansion counter 53 is thus incremented by one. When this counter reaches its first counting position, the output signal to the AND circuit 57 is interrupted, and the second column counter 55 does not count any further once with the zero signal from the dot clock generator 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 t , dot clock generator 41 emits a zero signal which advances first column counter 43, which in turn addresses the second scanning column of f in character generator decoder 19. The second column counter 55 also advances by one and the expansion counter 53 also advances from counting position 2 to counting position 3. Then the second scanning column of t is processed. At the end of this second column, the first column counter 43 switches again and addresses the third scanning column of the character in the character generator decoder 19.

The second column counter 55 also switches on and indicates to the comparator that two columns processed. The expansion counter 53 now moves from the counting position 3 to 4. After the end of the In the third scanning column, the dot clock generator 41 causes the first column counter 43 to be switched to 4 and the expansion counter 53 from 4 to 1. Whenever the expansion counter 53 runs into its first position, will its output signal for opening the AND circuit 57 is interrupted and ensures that the second column counter 55 does not join. Since the count of the second column counter 55 has not yet matched that of Step decoder 31 matches the value outputted, the first column counter 43 lets one continue counting initiate additional sampling cycle. When this cycle comes to an end, the dot clock 41 gives again a zero signal, switches the expansion counter 53 to 2 and now again leaves both column counters 43 and 55 advance by one. 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 mode switch 51 is placed in its third position C, the strain counter 53 is only effective as a three-stage counter. Before reaching its 1 position again, the expansion counter counts then only up to 3 in each case and causes an additional sampling column to be added for every two to be displayed Sampling columns. 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 accordingly 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. For this purpose, an additional operating mode switch position Al would have to be provided and on

is the operating mode signal derived therefrom to the character generator decoder 19 are supplied, due to this in characters with seven, eight or nine scanning columns one column is omitted. The same operating mode signal is also sent to the step decoder 31 fed to effect the output of an output value reduced by 1 from this, so that the Equality of step decoder and column counter output values is reached 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 scanning signal generation 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: e) an operating mode switch (51) for adapting the character-proportional spacing per character to a selectable, widened 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 (ZÄ) 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 3 equal to the step decoder output value. 2. Character generator according to claim 1, 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 another operating mode switch position (/ Il) 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.