Patent Publication Number: US-4320419-A

Title: Image reproduction equipment

Description:
This relates to recording on a single recording sheet from both a source of picture signals and a source of signals representing standard characters, such as alphanumeric characters. 
     According to the invention, such recording is effected by storing for each character to be recorded data defining a multi-column pattern of dots which make up that character in the recorded image, causing a recording head to scan a recording surface in a succession of parallel lines, addressing the character data store with a coded data signal representative of a selected character and with a column address signal generated in synchronism with the line scanning of the recording surface and defining a required column of dots for the selected character; and, during the scanning of the recording surface, applying to the recording head both a signal representing the picture data for the line which is being recorded and a signal derived from the store in accordance with the said character-selecting signals and column address signal and representing the dot pattern for the required column of the selected character. The invention also relates to apparatus for carrying the said method into effect. 
     In the preferred form, the apparatus also serves for register mark generation, the register mark data being stored in a separate store; the character store and the register mark store are addressed in parallel with a binary signal of which one digit serves to select one store or the other. 
     The register mark may occypy a single picture element in a single scanning line. 
    
    
     In order that the invention may be better understood, one example of apparatus embodying the invention will now be described with reference to the accompanying drawings, in which: 
     FIG. 1 illustrates a character recorded by a method embodying the invention; 
     FIG. 2 shows a register mark recorded to the same scale as the character of FIG. 1; and 
     FIG. 3 illustrates apparatus for carrying the method embodying the invention into effect. 
    
    
     In FIG. 1, the numeral 7 is represented by dots in an 8×6 matrix. For this numeral, only five columns are used and only seven rows. In this example, if a scanning pitch of 200/inch is in use (each scanning line being 1/8 mm wide) four scanning lines, each of width a, are required to reproduce one character dot, the dot occupying a column of width b. In a similar way, in each such scanning line the dot length is equal to four picture elements. At scanning pitches of 400 and 600 lines/inch, eight and twelve lines respectively are required for each dot of the character. 
     In the apparatus which is to be described register marks are recorded in addition to the alphanumerical characters. For register marks, a finer resolution of the dot pattern is required. For this reason a larger memory store is used, giving a dot size of approximately 1/8 mm. 
     Turning now to FIG. 3, an exposing drum 8, carrying a photosensitive sheet 9, is rotated by a motor 10. On the same shaft are two discs, a first disc 11 providing a signal once in each revolution of the drum, and a second disc 12 constituting an incremental encoder providing eight clock pulses per millimeter of drum circumference. A recording head 13 comprising a modulator 14 and a light source 15 is mounted on a lead screw 16 rotated by a driving unit 17 under the control of pulses from the disc 11. The pulses from the incremental encoder are counted in a row address counter 18. The pulses from the disc 11 are passed through a scan pitch counter 19 which has no effect on the pulse rate for a scanning pitch of 200 lines/inch and divides by two and three respectively for scanning pitches of 400 and 600 lines/inch. The pulses from the counter 19 are counted in a line counter 20. They are also applied to a character dot pitch counter 23 with a division of four. The circuit 23 provides one pulse every 4 lines (at 200 lines per inch); thus it provides one pulse for each dot-width or character column of travel of the recording head. These column address pulses are applied to a character column counter 25. The counter 25 supplies the memory 24 with a 3-bit signal representing the column address and also divides the incoming pulses by eight to supply to a character address counter 36 a pulse for each completed character width. In fact, the character width is only 6 columns, the remaining twolines being used for spaces between characters. 
     A delay counter 22 also receives the pulses from the disc 12, as well as the reset pulses derived from the disc 11. 
     Data representing the dot patterns which define all the characters which may be required is stored in a character memory store 24, each character being represented by signals corresponding to points defining the character in a matrix of rows and columns. Register mark data is stored in a store 26. 
     Seven-bit signals provided on a character data bus 28 define each required character (or register mark) in turn. The signals are temporarily stored in a character buffer store 30. From the store a 6-bit address signal is applied by way of line 32 both to the character memory store 24 and the register mark store 26. This enables the selection of one of up to 64 characters in the character memory store and can also be used to select one of 64 register mark &#34;characters&#34; although only one form of register mark is shown in FIG. 2 and only this mark and a &#34;negative&#34; thereof are used in the system which is being described. 
     A further 1-bit signal on line 34 is used as a switching bit to call up alphanumeric or register mark data from their respective stores. This bit is also applied to the row address counter 18 for use in the selection of different row and line counting rates, in particular to change the address when switching from character to register mark information. 
     The character address signal applied to the store 24, and the column address signal from the column counter 25, also applied to the store 24, together select signals corresponding to the required column of a dot pattern corresponding to the required character. It will be appreciated that for each revolution of the drum, a single column of each of a large number of dot patterns is selected, and this selection continues through a number of scanning lines until this column is complete. The remaining columns of the same characters are then selected in succeeding revolutions of the exposing drum; again, to complete each column a number of scanning lines is necessary. 
     The delay counter 22 sets the physical position of the characters around the drum circumference. It is reset to zero in each revolution by the reset pulses derived from the disc 11. It then counts the grating line pulses from the incremental encoder disc 12 until a preset value is reached. This preset value represents the point determined for the character information to be output on to film. At this point the row address counter 18 is enabled, and one line of character dot data is output on to film. 
     The character address counter 36, fed from the character column counter 25, steps the selection of characters from the buffer memory 30. This counter thus controls character positions horizontally along the drum. 
     The register mark store 26 is similarly addressed, except that a higher resolution is required because the mark can be anywhere in the matrix. For this reason, the store 26 receives a 5-bit line address signal from line counter 20 and a 2-bit row address signal from counter 18. 
     Eight-bit signals from the store 24 or the store 26 (whichever is selected) are multiplexed into serial form by an 8-to-1 line multiplexer 38, the output signals from which are combined with the analogue picture signal; following amplification in an amplifier 40, the resulting signal is applied to the modulator 14 to control the intensity of the light beam reaching the recording sheet 9. 
     The characters exposed on to the recording surface on the exposing drum may, for example, represent a trade house name to be present in the final reproduction or may represent information for an operator responsible for preparing the final reproduction. As an example, these characters could be used to identify three colour separations by printing on them &#34;cyan&#34;, &#34;magenta&#34; and &#34;yellow&#34;, respectively; or they may record the settings of various controls on the apparatus by means of which the colour separations were made. Problems can exist where separations are not properly identified. For example at the printing stage considerable expense can be involved in rectifying and/or having a to reproduce prints which have been produced from the wrong separations. The use of the present invention can obviate these problems. 
     It will be appreciated that in FIG. 3, the supply of trains of analogue picture signals, each train corresponding to one line of the original, is synchronised with the rotation of the drum 8, and that the supply of character-coded signals to the buffer memory 30 is similarly synchronised with the drum rotation.