GB2146817A - Printing apparatus - Google Patents

Abstract

A printing apparatus comprises a printing buffer (5) in which a plurality of print data with respective specified print sizes is stored, and a print size memory (7) for storing the maximum print size data in said print data. When print data read out from the printing buffer (5) is printed, the line height is set corresponding to the maximum print size data from the print-size memory (7). <IMAGE>

Description

SPECIFICATION Printing apparatus This invention relates to a printing apparatus which can automatically select the height of lines to be printed according to the printing size.

Some prior art electronic printing appara tuses, e.g., electronic typewriters, permit se lection of two different character sizes of dif ferent heights. In this case, when characters of the larger height are contained in a line, the printing sheet is fed for line change to a different extent than in the case when only characters of the low height are printed in a line. The fed amount of the printing sheet is selected by the user by operating a selection switch in correspondence to the height of characters on the basis of the line pitch or inter-line distance.

This, however, requires hardware for the switch. In addition, the switching operation is complicated. Further, if the fed amount of the printing sheet is fixed to that corresponding to the maximum printing height and the next line consists only of small characters, too much inter-line distance and wasted space will result because a large amount of the printing sheet has been fed.

This invention seeks to overcome the above drawback, and its object is to provide a print ing apparatus which can automatically select the height of a line according to the printing size.

The above object of the invention is attained by a printing apparatus which comprises: a buffer printing memory means in which a plurality of print data with respective specified print sizes are stored; a print size memory means for storing print data that is stored in said printing buffer memory means and of a maximum printing size in each line; line height setting means, connected to the printing buffer memory means and printing size memory means, for setting the height of each line to be printed with the printing size stored in the printing size memory means; and printing means connected to the line height setting means, for reading out printing data stored in the printing buffer memory means and printing the read-out data with the specified print size in a line having the preset line height.

With this construction of the printing apparatus according to the invention, the height of each line can be automatically set according to the printing size, so that the hardware of the sheet feeding switch can be dispensed with. In addition, the printing can always be effected with an optimum inter-line interval without the possibility of overlapping the adjacent printed lines or the creating of wasted space. It is thus possible to obtain effective printing on the printing sheet.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Figure 1 is a block circuit diagram showing an embodiment of the invention; Figure 2 is a view showing an example of print data, representing plot directions of printing, etc., stored in a character generator shown in Fig. 1; Figure 3(a) is a diagram for defining plot direction data representing directions shown by arrows; Figure 3(b) is a diagram showing the relation between each plot direction and corresponding number; Figure 4 is a view showing a step-by-step trace of a printing head; Figure 5 is a flow chart for explaining the data input operation of the construction shown in Fig. 1; Figure 6 is a flow chart for explaining the printing operation of the same construction;; Figure 7 is a view showing an example of data stored in the printing buffer shown in Fig. 1; Figure 8 is a view showing an example of print on printing sheet; Figure 9 is a block circuit diagram showing a different embodiment of the printing apparatus according to the invention applied to a dot printer; Figure 10 is a view showing the construction of a printing head 97 shown in Fig. 9 and the relation between each character size data and print dot length; Figure ii is a flow chart for explaining the data input operation of the construction shown in Fig. 9; and Figure 12 is a flow chart for explaining the operation of the same construction.

Now, an embodiment of the printing apparatus, according to the invention, applied to an electronic typewriter based on a drum type X-Y plotter will be described with reference to the drawings. Referring to Fig. 1, an input section 1 includes character keys, such as alphabet keys ic and numeral keys id, a print key la for commanding the printing, and a size key 1 b for setting a character size.

As the character size, there are, for instance, five different sizes which are represented by respective numeral codes "1" to "5". A desired character size can be set by a combination of operations of the size key I b and the corresponding numeral key. The character size represented by "1" is the standard character size, and the character sizes respectively represented by "2" to "5', have vertical and horizontal dimensions which are respectively 2 to 5 times those of the standard character sizes. Data provided from the input section 1 are fed to a CPU 2. The CPU 2 displays the input data on a display section 3 and also feeds print data and control data to an X/Y plot controller 4 according to the input data.

To the X/Y plot controller 4 are connected a printing buffer 5, a character generator 6, a memory 7, an X register 8 and a Y register 9.

The printing buffer 5 can store data for one print line. In the character generator 6 are stored plot direction codes, i.e., printing step codes, with respect to individual character codes UP/DOWN codes, END codes, etc. The memory 7 includes character size data registers SC and SC', an ASCII CODE data register KC and a plot direction data register C. Plotter drivers 10 and 11 are connected to the X/Y plotter controller 4. These plotter drivers 10 and 11 drive a X/Y plotter 1 2. More specifically, the plotter driver 10 controls the movement of the X/Y plotter 1 2 in an X-axis direction, i.e., the printing direction. The other plotter driver 11 controls the movement of a printing sheet in the X/Y plotter 1 2 in a axis direction perpendicular to the X-axis.The X/Y plotter controller 4 feeds step movement commands S, leftward movement commands L and UP/DOWN commands U/D to the Xdirection plotter driver 10, while it feeds step movement commands S and reversal commands R to the Y-direction plotter driver 11.

Fig. 2 shows an example of data stored in the character generator 6. The example of data represents an alphabet letter D. Numeral code "1" is a printing head down command code, numeral code "0" is a printing head up command code, code "ENDS" is a character end code, and the other numerals represent plotting directions. The significance of the numerals representing the plotting directions are as shown in Figs. 3(a) and 3(b).More specifically, numeral "4', represents the positive X-axis direction, "5,' represents the negative X-axis direction, "8" represents the positive Y-axis direction, "10" represents the negative Y-axis direction, "1 2" represents the resultant of the directions of "8" and "4',, "1 3', represents the resultant of the directions of "5" and "8", "14" represents the resultant of the directions "4', and "10", and "1 5" represents the resultant of the directions "5" and "10".

The operation of the embodiment will now be described with reference to the flow charts of Figs. 5 and 6. In the first place, the data input operation will be described with reference to Fig. 5. First, a desired character size is set by a combination of operations of the size key 1 b and the corresponding numeral key. In a case when no particular character size is specified, numeral ''1'', representing the minimum character size, is selected by code data. When various character and other data are keyed in the input section 1, they are displayed on the display section 3 and are also fed through the CPU 2 to the X/Y plotter controller 4 to be written in the register KC in the memory 7 in step Al. The input data are written as ASCII codes in the register KC.At this time, a desired character size can be specified by operating the corresponding numeral key for numerals "1" to "5", representing the respective different character sizes. The operation of the numeral key for the specification of the character size, however, is effective for character size setting when and only when the size key has been operated immediately before the numeral key operation. A check to see whether the numeral data for character size designation has been input immediately after the size key operation is made in step A2. If it is found that the numeral data has been input immediately after the size key operation, the routine goes to step A3. In step A3, a check is made to see whether the data in the register KC is in the range of "37" to "35" as ASCII code, i.e., in the range of numerical value "1" to "5".If the register data is outside the ASCII code range of "31" to "35", there is no character size to be selected, the routine goes to step A4, which is an error processing, before bringing an end to the data input routine. If the register data is within the ASCII code range of "31" to "35", step A5 is executed subsequent to step A3. In a case when, for instance, the numeral key for "5" has been operated right after the size key operation for selecting the character size of "5", in step A5 the X/Y plot controller 4 performs an arithmetic operation "KC-30" to obtain the charcter size data "5" and writes this value into the register KC.The routine then goes to step A6, in which a check is made to see whether the data in the register KC is greater than the character size data that has been stored in the register SC. If the former data is greater than the latter, the former data is written as newly selected character size data into the register SC in step A7.

In other words, the maximum value of the character size data for the pertinent print line is stored in the register SC. The routine then goes to step A8. If it is determined in step A6 that the condition KC > SC is not satisfied, the routine immediately goes to step A8. In step A8, the data in the register KC is written into the printing buffer 5, thus bringing an end to the data input routine. If it is determined in step A2 that the numeral data input is done not immediately after the size key operation, i.e., the input data is ordinary numeral data "5", the routine goes to step A9, in which a check is made as to whether the printing buffer 5 is full. If it is not full, the routine goes to step A8. If the printing buffer 5 is full, step A10, is performed which is an error processing, thus bringing an end to the routine. Fig. 7 shows an example of the data stored in the printing buffer 5. In this case, data representing alphabet letters "A" to "I" are written as print data. The character size represented by the ASCII code "02" is specified for the letters "D", "E" and "F", and the character size represented by the ASCII code "01" is specified for the letters "G", "H" and "I". No character size is specified for the letters "A", "B" and "C", so that these letters are handled as ASCII code "01" size letters. After the print data a line end code "END2" is written.

To print the data stored in the printing buffer 5, the print key 1 a of the input section 1 is operated. The X/Y plotter controller 4 then starts controling the X/Y plotter 1 2 as shown in the flow chart of Fig. 6.

In step B1, the X/Y plotter 12 is moved in V" direction from the home position HP1 of the predetermined line (Fig. 8) for the distance corresponding to the size of the largest character at this line. More specifically, the multipliation, "6 steps X [SC]," is performed, and the product of this multiplication, i.e., the step advance instruction S is input to the Y-direction plotter driver 1.Value "6 steps X [SC]" indicates the number of steps by which the printing paper is relatively moved in " + Y" direction and which is obtained by multiplying 6 by the numerical code stored in the SC register. "6" is the number of steps by which the head moves in the Y-axis direction to print a character of the standard size "1." The numerical code stored in the SC register represents the size of the largest character at the line. Suppose the data shown in Fig. 7 is stored in the printing buffer 5. Then, the code stored in the SC register is "02" (that is, (SC] = 2). In this case, the product of the multipliation, "6 steps X (SC]" is 1 2 steps.

The above-described operation will be explained, taking the second line to be printed (Fig. 8) as an example. First, the home position of the printing head is at the left upper end HP1 of this line. In step B1, the height of this print line is set to conform to the maximum print character size in this line, and the position of the printing head relative to the printing sheet is moved from the position HP1 to a position HP2 corresponding to the line height, which is the home position for the first print character in this line. This means that the X/Y plotter 1 2 is moved to the left lower end of the line at the start of printing. In a subsequent step B2, the standard character size ASCII code "01" is written as character size data in the register SC.In a subsequent step B3, the first print character data is read out from the printing buffer 5 into the register KC. The routine then goes to step B4, in which a check is made to see whether the data read into the register KC is a character size code. If the data is a character size code, it is transferred to the register SC in step B5.

In a subsequent step B6, the next print data is read out from the printing buffer 5 into the register KC, and the routine goes back to step B4. If it is determined in step B4 that the data in the register KC is not any character size code, the routine goes to step B7, in which an area of the character generator 6 corresponding to the character code stored in the register KC is designated. In a subsequent step B8, the first step data in the designated area in the character generator 6 is read out and set in the register C. In a subsequent step B9, the character size ASCII code "01" is set in the register SC'. The routine then goes to step B10. In step B10, the X/Y plot controller 4 feeds drive signals to the drivers 10 and 11 according to the data in the register C, thereby driving the X/Y plotter 1 2 for printing.In a subsequent step B11, the data in the X and Y registers 8 and 9 are updated to new printing position co-ordinates. Then step B1 2 is executed, in which a check is made to see whether the character size data in the registers SC' and SC are equal. If these data are not equal, the data in the register SC' is incremented by "1" in step B13, and the routine goes back to step B10. When the character size ASCII code "01" has been specified, it is determined in step B1 2 that SC' = SC, thus bringing an end to the movement of the printing head 1 3 with respect to this step. When the character size ASCII code "02" has been specified, the steps B10 through B1 3 are repeatedly executed according to the character size.If it is determined in step B1 2 that SC' = SC, the routine goes to step B14. In step B14, the next step data is read out from the character generator 6 and set in the register C. Then step B15 is executed, in which a check is made to see whether the data that has been read into the register C is an end code. If it is not an end code, the routine goes back to step B9 to repeat the sequence of steps described above.

In a case of printing a letter "D" baced on the ASCII code "01", for instance, step data as shown in Fig. 2 is read out from the character generator 6. More specifically, step data "1" is a first read out from the character generator 6. This step data "1" is a DOWN command, so that the printing head 1 3 is brought down into contact with the printing sheet. For the next 6 steps, step data "8" is read out. This data "8" represents the positive Y-axis direction as is seen from Figs. 3(a) and 3(b). The X/V plotter 1 2 is thus moved 6 steps in the positive Y-axis direction from the home position as shown in Fig. 4. For the following 3 steps, data "4', is read out, so that the X/Y plotter 1 2 is driven 3 steps in the positive X-axis direction.The following step data is "14", so that the X/Y plotter 1 2 is driven one step in the resultant positive Xaxis and negative Y-axis directions. For the following 4 steps data "10" is read out, then data "1 5 is read out for one step, and then data "5" is read out for 3 steps. In this way, printing of the latter "D" is effected. Thereafter, step data "0" is read out, which is a printing head UP cornmand. Then data "4" is read out for the following 6 steps, so that the printing head is brought to the home position for the next character to be printed (i.e., the left lower end of the character). Then, a character end code "END1" is read out from the character generator 6.As has been shown, when the printing of one character is completed, the character end code "END1" is read out from the character generator 6 into the register C. The check in step B15 thus yields "YES". so that the routine goes to step B16, in which the next print data is read out from the printing buffer 5 into the register KC.

Then step B17 is executed, in which a check is made to see whether the data having been read into the register KC is a line end code "END2". If it is not the line end code "END2", the routine goes back to step B4 to start processing the next character. In this way, character data stored in the printing buffer 5 are progressively read out and printed. When the line end code "END2" is finally read out from the printing buffer 5, the check in step 81 7 yields "YES", so that the routine goes to step 818. In step B18, the X/Y plotter 12 is returned. Then in step B19, the X/Y plotter 1 2 is moved 6 steps in the negative Y-axis direction.More specifically, in step B18 the X/Y plotter 1 2 is brought to the left lower end, i.e., home position HP2, of the completed print line. Then in step 819 the X/Y plotter 1 2 is brought to the left upper end, i.e., home position HP1, of the next print line. Fig. 8 shows an example of print, in which the second printed line corresponds to the data shown in Fig. 7 and stored in the printing buffer 5. For the first three letters "A", "8" and "C" no character size is specified, so that these characters are printed in the standard character size represented by the ASCII code "01".The following letters "D", "E" and "F" are printed in the specified character size represented by the ASCII code "02", and the letters "G", "H" and "I" are printed in the specified character size represented by the ASCII code "01". In the above way, the height of each print line is automatically set in conformity to the maximum character size in that line.

The above example has been taken for the case where characters of specified character sizes can all be printed in a line even if the specified character sizes are 2 to 5 times the standard character size. In a case where 2 to 5 times the standard character size is specified and the characters of the specified character size cannot all be printed in a line, the remaining characters are of course printed in the next line. According to the gist of the invention, the height of the next line should naturally set to the maximum character size in that line. To this end, a step may be added for searching the maximum character size among the print data for the next line at the end of printing a first line. Further, the character size may be varied as desired according to the data stored in the printing buffer 5 during the keying of the character data.Furthermore, the height of a line corresponding to the maximum character size therein may be determined after the keying of the character data and immediately before the start of actual printing.

Furthermore, while in the above embodiment the printing operation has begun in response to the operation of the print key 1 a, it is possible to automatically begin the printing for one line. For example, a check may be made in response to the keying of every data to see whether there is data for printing in a memory area for a one print line that is determined by a memory area in the printing buffer 5, and the printing may be automatically started when it is determined that the maximum area for a one print line is full of input data and a read-to-print number is reached by the number of input characters.

Further, in the above embodiment the X/Y plotter 1 2 has driven in the X-axis directions while driving the printing sheet in the Y-axis directions through the drive 11. However, the invention is equally applicable to a case where an X/Y plotter 1 2 capable of being moved in both the X- and Y-axis directions is used.

Further, the invention is applicable to vertical print lines as well as horizontal print lines.

Further, the invention is applicable not only to X/Y plotters but also to printing apparatuses where the print character size is variable, e.g., serial dot printers, line dot printers and other dot printers. Furthermore, the invention is applicable not only to typewriters but also to various printing apparatuses capable of printing data in variable size.

Now, a different embodiment of the invention applied to a dot printer will be described with reference to Figs. 9 through 1 2.

Fig. 9 is a block diagram showing an essential part of a serial dot printer, for instance of a thermal printer type. This structure is similar to the preceding embodiment shown in Fig.

1. and although not shown, the structure includes the equivalent to the input section 1, CPU 2 and display section 3 shown in Fig. 3 in similar connection.

Dot print input is fed from input section 1 (not shown) through CPU 2 (not shown) to a dot print controller 90. To the dot print controller 90 are connected a printing buffer 91, a RAM 92 and character generators 93 and 94 for the transfer of data and/or signals to and from the dot print controller 90. The RAM 92 includes a key code (i.e., ASCII code) register KC, a character size data register SC, a counter CN and a reading-to-print area register MC. The counter CN counts " + "s when the character size represented by the ASCII code "01" is specified. It counts " + 2's when the character size represented by the code "02" is specified. In this way, it can perform counting corresponding to each of the available character sizes up to that represented by the code "05".The ready-to print area register is one, in which a ready-toprint area for one line is stored. For example, if character data for 24 characters of the character size represented by the code "01" can be printed, a value "24" is stored. The dot print controller 90 always provides a character size designating signal to the sections CGO1 to CG05 of the character generator 94. The character generator 94 stores dot pattern data constituting each character, and when printing a character of the character size of the ASCII code "01", a character size designating signal S1 is provided from the dot print controller 90 to the section CG01 of the character generator 94.Each section of the character 94 stores dot pattern data constituting each character and the section CG02 is given a size designating signal S2 when printing a character of the character size of the ASCII code "02".

A printing head driving section 95 is driven by a dot pulse signal from the dot print controller 90 to drive the printing head 97 in the width direction of the printing sheet. A printing sheet driving section 96 is connected to the dot print controller 90 and feeds the printing sheet in the direction perpendicular to the direction of movement of the printing head 97. The printing head 97 has 31 thermal printing elements as shown in Fig. 10, and it is connected to the printing head driving section 95 and dot print controller 90. It causes selective heat generation of the printing elements according to the drive signal from the printing head driving section 95 and dot pattern data from the dot print controller 90, thereby effecting the corresponding dot printing on the printing sheet.When the character size of the ASCII code "01" is specified, 7 thermal printing elements of the printing head 97 are driven. When the print characters of a line are all of the character size of "01", fed amount of a sheet corresponding to 7 dots of print is set for the printing of the next line.

When the character size of the ASCII code "02" is specified, 1 3 thermal printing elements are driven. When some of the print characters in the line are of the character size of "02", the printing sheet is fed by an amount corresponding to 1 3 dots for the printing of the next line. The printing sheet is likewise fed when there are print characters with the sizes of "03" to "05". In this embodiment of the printing apparatus, applied to a dot printer, the height of a print line correspoding to the maximum character size in that line again can be determined immediately before the start of the actual printing.

Also, it is possible to cause autornatic printing of a line. To this end, a check is made in response to the keying of each data to see whether there is data to be printed in a one line ready-to-print area determined by an area of the printing buffer, and the printing is caused when a ready-to-print character number is reached.

Now, the operation of the dot printer of the above construction will be described with reference to the flow charts of Figs. 11 and 1 2.

In the first place, the data input operation will be described with reference to Fig. 11.

Again in this embodiment, the character size is specified by the operation of a size key for setting a character size and a corresponding one of numeral keys for "1" to "5", respesenting respective character sizes. An input code is fed as the ASCII code to the register KC in the RAM 2 in step C1. The input of numeral data representing character size is effective when and only when it is immediately after the operation of the size key.

Accordingly, a check is made in step C2 to see whether the numeral data has been done immediately after the operation of the size key for setting the character size. If the check in step C2 yeilds "YES", the routine proceeds to step C3, in which a check is made to see whether the data in the register KC is in an ASCII code range of "31" to "35", i.e., ion a numerical value range of "1" to "5',. If the data in the register KC is outside the ASCII code range of "31" to "35", there is no character size to be selected, so that the routine goes to step C4, which is an error processing step, thus bringing an end to the rotine.If the data in the register KC is within the ASCII code range of "31" to "35", step C5 is executed, in which the dot print controller 90 performs an arithmetic operation "KC-3O". The result is written as character size data in the register SC in a subsequent step C6. That is, the maximum character size data for the pertinent line to be printed is stored in the register SC. Then, in step C7 the data in the register KC is written in the printing buffer 91, thus bringing an end to the data input routine.

It it is judged in step C2 that the operation of the numeral key is done not immediately after the size key operation, the routine goes to step C8, in which the count of the counter CN is added to the data in the register SC, which is either one of numeral, "1" to "5" according to the codes "01" to "05", and the result is written in the counter CN. In a subsequent step C9, a check is made to see whether the sum data written in the counter CN is less than the value stored in the register MC. If the decision is "YES'', it is determined that the printing buffer 91 still has remaining area for writing character data. The routine thus goes to step C7, in which the data in the register KC is written in the printing buffer 91. if the decision is "NO", the routine goes to step C10, in which a check is made to see whether the count of the counter CN coincides with the data in the ready-to-print area register MC. If the decision is "YES", step C11 is executed, in which the code data that is keyed this time is written in the printing buffer 91, and it is then automatically printed.

If the decision is "NO", i.e., if CN MC, the character number is in excess of the ready-to print number, the code data keyed this time is ignored, and only the previous character data is automtically printed.

Now, the printing operation will be described with reference to the flow chart of Fig.

12.

First, in step D1 the maximum character size data in the printing buffer 91, represented by one of the ASCII codes "01" to ''05'',is searched and written in the character size data register SC. According to the data in the register SC, the fed amount of the printing sheet is determined to be one in a range of 7 dots to 31 dots in step D2. In a subsequent step D3, the ASCII code "01", which is the standard character size data, is written in the register SC. In a subsequent step D4, an initial value of "O" is set in the counter CN.

In a subsequent step D5, the first print data is read out from the printing buffer 91 into the key code data register KC. In a subsequent step D6, a check is made to see whether the data read out from the register KC is a character size code. If it is a character size code, step D7 is executed, in which one of the sections CGO1 to CG05 in the character generator 94 is selected, which corresponds to that character size designating signal. In a subsequent step D8, the next print data is read out from the printing buffer 91 into the register KC, and then the routine goes back to step D6. If it is determined in step D6 that the data read out into the register KC is not size code, the routine goes to step D9.In step D9, one of the sections CG0l to CG05 in the character generator 94 that corresponds to the character code stored in the register KC is specified. In a subsequent step D10, the printing elements of the printing head 97 are selectively energized according to the dot pattern area in the specified section, thus effecting dot printing on the printing sheet, and then a dot pulse signal is fed to the printing head driving section 95 to drive the printing head 97 by an amount corresponding to one dot to the right. In a subsequent step D11, the numeral data in the register SC is added to the count of the counter CN, and the sum is written in the counter CN.In a subsequent step D12, a check is made to see whether the count of the counter CN is no less than the data in the ready-to-print area register MC, i.e., whether CNMC. If the decision is "YES'', it is determined that the printing of one line has been completed, so that the routine goes to step D13, in which the printing head 97 is returned for the printing of the next line. If the decision in step D12 is "NO", the routine goes back to step D5 to continue the printing operation for the present line. The sequence of steps described above is thus repeated.

As has been shown, the dot printer as well the height of the print line can be automatically determined according to the character size in that line, so that it is possible to obtain effective printing on the printing sheet.

In the embodiment described above, the size of a character to be printed is represented by ASCII codes "01" to "05." Nonetheless, the best mode of the present invention may be that characters of the sizes corresponding to codes "01" and "02" If this is the case, the character generator 94 (Fig. 9) will comprise only two sections CG0l and CG02. The arrows (Fig. 10) will show the paper-feeding amounts corresponding to codes "01" and "02," and the operation "KC = "31" or "32" will be performed in step C3 in the flow chart (Fig. 11).

Claims (6)

1. A printing apparatus comprising: printing buffer memory means in which a plurality of print data with respective specified print sizes are stored; print size memory means for storing print data that is stored in said printing buffer memory means and of a maximum print size in each line; line height setting means, connected to said printing buffer memory means and said print size memory means, for setting the height of each line to be printed with the print size stored in said print size memory means; and printing means, connected to said line height setting means, for reading out printing data stored in said printing buffer memory means and printing the read-out data with the specified print size in a line having the present line height.

2. The printing apparatus according to claim 1, wherein said line height setting means includes an X/Y plot controller and a plotter driver for controlling the movement of a printing sheet in the direction of a Y-axis.

3. The printing apparatus according to claim 1, wherein said line height setting means includes a dot print controller and a printing sheet feed driving section.

4. The printing apparatus according to claim 1, further comprising means for designating various items of data to be printed and the sizes of characters in which these items are to be printed, and means for selecting the size of the largest character at any line stored in said printing buffer memory means every time said means designates one printing size, the size data thus selected being written in said print size memory means.

5. The printing apparatus according to claim 1, further comprising means for selecting the size of the largest character at any line stored in said printing buffer memory, the size data thus selected being written in said print size memory.

6. A printing apparatus, substantially as hereinbefore described with reference to the accompanying drawings.