Method and apparatus for simultaneously outputting a graphic signal and an alphanumeric signal by using an image reproducing system

Graphic signals and literal (or drawing) signals are recorded substantially simultaneously by increasing or decreasing the number of beam components output from at least one of a literal head and a graphic head after a specified number of scanning lines, both of which heads are being synchronously fed in the sub-scanning direction. Variation of the number of beam components used in the head is used to change the scan length of the head, for synchronizing the feed pitch therefor with the feed pitch of the other head when the scan lengths of the two are not integrally related. Differences between the feed pitch and the scan length of the variable scan length recording head are corrected by slight adjustments of the head position in the sub-scanning direction.

FIELD OF THE INVENTION 
This invention relates to reproduction of images by using devices such as 
color or monochrome scanners, and especially to such a reproduction in 
which both a pictorial or graphic signal and an alphabetic or numeric 
signal are output for substantially simultaneous recordation by two 
recording heads. 
BACKGROUND OF THE INVENTION 
Generally, printed material contains both pictorial (i.e. graphic) and 
alphanumeric (i.e., literal) components (the latter including drawing 
components), each of which is treated separately in a conventional process 
of photomechanics. Conventionally, both components are subsequently 
combined to form a complete reproduced image prior to the process of 
producing a press plate. However, this procedure is complicated and thus 
requires and consumes excessive quantities of time. 
There has thus been recently developed a new type of image reproducing 
system. The newly developed system, a so-called "full-page make up system" 
or "total (lay-out) scanner" is being put to practical use in various 
fields. This system provides a scanner which utilizes a method of 
distributing pictorial and alpha-numeric components into desired positions 
by means of an all-electronic approach to the photomechanical process. 
In the electronic approach, the graphic and literal components are input as 
signals to resepective input devices. The signals are then separately 
processed, since each component signal has a distinctive data structure. 
Furthermore, the literal data signal is converted into a raster-scanned 
data signal which is identical to that of the graphic data in order to be 
output simultaneously therewith by a recording device. 
Of course, the literal data can be obtained as raster-scanned data from 
scanning of block copy which is preliminarily laid out in a desired 
formation. At any rate, in the prior art it is difficult to record both 
the graphic and literal components of the data simultaneously. 
The difficulty arises not only because literal components require a higher 
resolution (smaller pixels), but also because graphic components are 
required to be variably recorded as functions of a halftone dot scale 
thereof (depending on the number of lines in a screen ruling) on request 
when recorded with halftone screens. 
One prior art method for resolving this problem includes the steps of 
setting a scale of several graphic pixels for each of the literal pixels, 
and scanning a photosensitive material for recordng thereon, the scan 
having a predetermined number of lines with respect to that of graphic 
pixels. In said method multiple beam components, each of which can be 
individually controlled, may be arranged to form a line across the width 
of a scanning line (see, for example, U.S. patent application Ser. No. 
390373). However, the above method is defective in having a reduced 
capacity for responding to a request for variation of the number of screen 
ruling lines. 
Particularly, the setting of a desired number of screen ruling lines is a 
difficult task when the number is to be varied. Additionally, in order to 
maintain an integer proportional relation between literal and graphic 
pixels, there must be a sufficient number of beam components to cope with 
the requirement for a change in the number of said beam components due to 
variation in screen ruling, which results in a more expensive system. 
Another method discloses the provision of separate scanning heads for 
graphic pixels and for literal pixels, the heads being used for recording 
(or exposing) the two types of pixels sequentially-e.g., first recording 
all the graphic pixels and thereafter recording all the literal pixels. 
This approach, however, requires performance of two whole scans by the 
heads. Although this is a reasonable approach for providing different 
recording beams having the respective appropriate diameters, the resulting 
exposure (or recording) time is doubled compared to that of simultaneous 
exposing. 
SUMMARY OF THE INVENTION 
In view of the above-described conventional problems, the present invention 
overcomes the prior art defects by providing separate scanning heads for 
each of the graphic (pictorial) pixels and the literal pixels and by 
rendering the separate heads, which have different numbers and diameters 
of their beam components, capable of a simultaneous recordation of images 
in a practical manner when the heads are moved in a sub-scanning 
direction. 
It is thus a primary object of this invention to provide an image 
reproducing system capable of recording graphical and literal components 
simultaneously by using two scanning heads, each having a beam producer 
including a respective number and diameter of beam components, selected so 
that the heads may be used substantially simultaneously, and to 
synchronize feeding pitches of both beams in the sub-scanning direction by 
varying the number of beams (and thus the scan length) of at least one of 
the scanning heads, for example the literal components' scanning head, 
every specified number of scanning lines. 
It is a further object of the invention to provide an adjusting 
displacement for one of the scanning heads in the sub-scanning direction 
to correct for discrepancies between the feeding pitch thereof and an 
integer multiple of the scan lengths thereof. 
The above and other objects and features of this invention can be 
appreciated more fully from the following detailed description when read 
with reference to the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring to the drawings, FIG. 1 is an example of an image reproducing 
system to which the method of this invention is applied, which is composed 
of an input signal treating part I and an output signal controlling part 
II and an output part III. For the system of FIG. 1, the method of 
treating input signals of graphic and literal data is first explained as 
follows. 
Literal data from a literal input device 8 are stored as a file in a memory 
(not shown) of a CPU (central processing unit) 15 after being converted 
into literal codes, representing the literal. Then, by designating the 
desired addresses of said literal codes according to a layout chart 
prepared in advance by a digitizer 9, literal font data corresponding to 
said literal codes are retrieved from a literal font memory 13 and input 
to a literal (and drawing component) memory 12. 
Certain drawing data, such as used in charts or ruled lines, however, may 
also be written into certain cells of the literal memory 12 with addresses 
determined in the same manner as for literal data. 
Furthermore, these literal and drawing data can be modified on request by 
the use of a modification graphic device 14 composed of a display, such as 
a CRT displaying device. 
It is noted that binary data representing either a literal or drawing 
element may also be input by scanning of an input scanner 10 independently 
of the aforesaid method. 
On the other hand, graphic data obtained from an original picture with use 
of the input scanner 10 undergo color correction, magnification 
conversion, etc., and are stored in a temporary memory device (not shown 
in the drawings). Thereafter, having been designated their addresses by 
the digitizer 9 and the graphic output device 14 according to a layout 
chart which may be useful as well for the literal components, said graphic 
data are written into the designated cells of a graphic memory 11. 
In this manner, graphic and literal data are output to a graphic output 
head 1 and a literal output head 2 respectively, which are synchronized in 
their feeding pitch in the sub-scanning direction by means of a common 
feeding gear 22, according to address signals to control laser beams for 
recording graphic and literal components. The beam components output by 
heads 1 and 2 are imaged on drum 20 by imaging lenses 17 and 18, 
respectively. 
The graphic and literal heads, however, may have different numbers and/or 
diameters of their respective beams, which fact renders it impossible to 
synchronize the heads in a common feeding pitch in the sub-scanning 
direction. The solution of this problem is the main purpose of this 
invention. 
FIG. 2 shows the general concept of this invention, in which B.sub.1 
represents laser beam components of the graphic output head 1. Preferably, 
the components B.sub.1 are 1/4000 inch in diameter and graphic output head 
1 is capable of emanating ten beam components at a time as illustrated by 
components 1, 2 of B.sub.1. B.sub.2 represents laser beam components of 
the literal output head 2 (provided for responding to literal and drawing 
data signals), the beam components preferably being 1/1000 inch in 
diameter. The literal output head 2 is preferably capable of emanating 
either two or three beam components selectively at a time, as illustrated 
by components 1, 2 of B.sub.2. 
In the above illustration, the graphic output head can scan a width of 
d.sub.1 =1/4000.times.10=1/400 inch at a time, defined as the scan length 
thereof, while the literal head 2 can scan a width of d.sub.1 
'=1/1000.times.2=2/1000 inch, defined as the scan length thereof when two 
beam components are used at a time. The difference in scan lengths thus 
prevents synchronization of feeding pitches of the two heads. However, it 
is noted that in two scan times the graphic output head 1 scans a width of 
d.sub.2 =2/400=1/200 inch, while the literal output head 2 can be made to 
scan a total width of d.sub.2 '=2/1000+3/1000=1/200 inch in two scans if 
the number of beam components thereof is changed from two to three in the 
two scans. Thus, the total widths d.sub.2 and d.sub.2 ' scanned in two 
scans may be made to coincide. 
In other words, in accordance with the present invention there is provided 
a variable scan length recording head, having two scan lengths (for 
example) which are shorter and longer than the scan length of the second 
recording head. The scan length is varied so that the sum of small integer 
multiples of the two scan lengths of the one head corresponds to a small 
integer multiple of the scan length of the second head, thereby permitting 
synchronization of sub-scan feeding of the two heads. 
In the aforesaid method, however, since the literal output head 2 
alternately uses two and three beam components to complete the scanning of 
a width equivalent to that of five beam components, there results a 
discontinuous scan if the feeding pitch of the literal head 2 is 
synchronized (at 1/400 inch) with that of the graphic output head 1. This 
problem is overcome as follows. 
The present invention employs a literal head 2 which has a beam producer 
capable of scanning with either three or two beam components as is shown 
in FIG. 3(b) when a scan shown in FIG. 3(a) is to be performed. That is, 
after performing a first scan with two beam components, as shown in FIGS. 
3(b-1), a scan is carried out with three beam components as shown in FIG. 
3(b-2). To perform the second scan, the literal output head 2 is fed 
(displaced) in the subscanning direction by a feeding pitch .alpha. (in 
this embodiment,=1/400 inch) in synchronism with the movement of the 
graphic output head. At the beginning of the second scan a gap .beta. 
results, representing the difference between the common pitch and the scan 
length of the two beam components of head 2. In this embodiment, gap 
.beta.=1/400-2/1000=1/2000 inch, which is equivalent to half the diameter 
of said beam components. This gap exists between the place where the head 
is and the place where it should be for continuous scanning to take place 
in the sub-scanning direction, as shown in FIG. 3(b-2). However, it is 
noted that in carrying out a scan with two beam components as shown in 
FIG. 3(b-3) after the scan of FIG. 3(b-2), the literal output head is 
again displaced by .beta., resulting in an overlap of 3/1000-1/400=1/2000 
inch for the two scans, corresponding to the difference between the scan 
length of the three beam components and the pitch. 
The present embodiment employs the literal output head 2 as follows to 
correct the gap and to eliminate the overlap on the sub-scanning line. 
FIG. 4 is an illustration explaining the structure of the inventive literal 
output head, in which 25 is a chassis for the literal output head 2 which 
is moved in synchronism with the graphic output head 1, 26 is a beam 
producer which is capable of being moved independently for adjustment, 28 
is a type of piezo-electric material which may have a characteristic as 
illustrated in FIG. 5, one end of which material is fixed to a side of the 
beam producer and the other end of which is fixed to the chassis. 
Therefore, in a so-called blanking time provided between the first and 
second scans, input of a control signal to a high voltage producer 29 
results in the piezo-electric element 28 changing its form to shift the 
beam producer 26 somewhat, independently of feeding in the sub-scanning 
direction, thus resulting in adjusting the gap .beta. shown in FIG. 
3(b-2). 
For the third scan time, cutoff of the high voltage signal of high voltage 
producer 29 results in setting the beam producer 26 back to its original 
position appropriate for the next scan. Thus, the overlap between the 
second and third scans is eliminated. By repeating the aforesaid routine, 
subsequent scanning can be performed resulting in simultaneous recording 
of graphic and literal components, 
It should be noted that a lens to focus the beam from the beam producer 26 
on a recording drum 20 may be movable in accordance with that of the beam 
producer 26, or may be fixed if the lens is capable of covering the above 
described shifting of the beam producer 26. Furthermore, the method of 
this invention may be applied to more complicated cases. 
Assuming that the diameter of beam components of the graphic output head 1 
is a.sub.1, the number of its beam components is n.sub.1, the diameter of 
beam components of the literal output head 2 is a.sub.2, and the number of 
its beam components is n.sub.2 or n.sub.3 (n.sub.3 =n.sub.2 +1) having a 
relationship between them of n.sub.2 a.sub.2 &lt;n.sub.1 a.sub.1, n.sub.3 
a.sub.2, the shifting distance can be calculated as follows: 
The first time: n.sub.1 a.sub.1 /a.sub.2 =n.sub.2 +.alpha..sub.1 
where n.sub.2 is an integer and .alpha..sub.1 is a decimal. 
##EQU1## 
The same calculation can be applied to subsequent scanning lines. For 
example, where the feeding pitch for the graphic output head 1 is supposed 
to be 350 lines per inch (=71.43 .mu.m pitch) and feeding pitch for the 
literal head 2 is supposed to be 1000 lines per inch (=25 .mu.m pitch) (in 
this case the latter is per one beam component), the required shifting 
distances are obtained as follows. For seven feeds of the graphic output 
head, 500 .mu.m will be scanned, as will be the case for twenty beams of 
the literal head. After the k.sup.th 71.43 .mu.m feed of the graphic and 
literal heads, the cumulative feed of the two heads will total (k)(71.43 
.mu.m). The number of beam elements of head 2 to be used during the 
k.sup.th scan is determined by determining a cumulative beam width which 
is closest to the cumulative feed displacement, subtracting therefrom the 
total cumulative beam width closest to the (k-1).sup.th cumulative feed, 
and dividing the difference by the beam width. The cumulative beam width 
closest to the (k-1).sup.th feed is defined as the integer multiple 
component of team diameters closest to the amount of feed provided in k-1 
feeds. The necessary shifting of the literal head for the k.sup.th scan is 
determined by subtracting the cumulative beam width closest to the 
cumulative feed for the k.sup.th scan from the cumulative feed of the 
k.sup.th scan. Thus, during the seven scans for the present example, the 
following results are obtained. 
______________________________________ 
No. of 
Beam Scan Cumulative 
Shift 
Scan Com- Length for 
Cumulative 
Beam Ad- 
No. ponents k.sup.th Scan 
Feed Width justment 
______________________________________ 
1 2 5.0. .mu.m 
71.43 5.0. 21.43 .mu.m; 
2 3 75 .mu.m 142.86 125 17.86 .mu.m; 
3 3 75 .mu.m 214.29 2.0..0. 14.29 .mu.m; 
4 3 75 .mu.m 285.72 275 1.0..72 .mu.m; 
5 3 75 .mu.m 357.15 35.0. 7.15 .mu.m; 
6 3 75 .mu.m 428.58 425 3.58 .mu.m; 
7 3 75 .mu.m 5.0..0. 5.0..0. .0...0..0. .mu.m. 
______________________________________ 
In this case, two beam components of the literal output head 2 are used at 
the first time, and three beam components of the letter output head 2 are 
used at the second and following cycles and shifting the beam producers of 
the literal output head 2 by the shift adjustment determined in accordance 
with the foregoing procedure enables the literal output head 2 to move in 
accordance with the graphic output head 1 in the sub-scanning direction. 
FIG. 6 shows a structure of a literal output head 2 
FIG. 6 shows a structure of a literal output head 2 of another embodiment 
of the invention, in which adjusting screws 30, 31 and an electromagnetic 
solenoid 32 are employed instead of the piezo-electric element 38. 
In FIG. 6, to correct the gap .beta. the solenoid 32 is provided for 
adjusting the position of the beam producer 26 independently of the 
chassis 25, the adjusting distance being set by the screws 30,31. 
The present invention can also be realized by using a literal output head 2 
which has a two beam producer 21a and a three beam producer 21b without 
performing an adjustment. More precisely, as shown in FIG. 7(b), the axis 
(1') of both beam producers 21a, 21b may be shifted by one fourth of a 
beam diameter in the sub-scanning direction with respect to the axis 1 of 
the chassis (in this case by 1/4000 inch). Thus, at the end of the first 
scan by the two beam producer 21a, the two beam producer situates at the 
location shown in a broken line in FIG. 7(a), and the three beam producer 
21b automatically situates in a proper position without producing either a 
gap or an overlap on the sub-scanning line. In FIG. 7, .DELTA.L is a gap 
on the main scanning line between the beam producers 21a and 21b which is 
to be appropriately set according to such parameters as a revolution speed 
of a recording drum 20. 
As mentioned above, a reproduced image with properly laid-out graphic and 
literal components is produced by use of the output control unit II and 
the output unit III as is shown in FIG. 1. The following is an explanation 
of said units II and III. 
In operation, a pair of timing pulses is produced by an encoder 19 and an 
output scanner control circuit 6. A timing pulse Pa is generated to 
control the graphic output head 1 and a timing pulse Pb to control the 
literal output head 2. The timing pulse Pa is used as a signal to output 
graphic data D.sub.1 from an interface 5 to a dot forming circuit 4. The 
graphic data D.sub.1, after being stored in a buffer memory 5' of said 
interface 5, are changed into proper data format for said dot forming 
circuit 4. 
The timing pulse Pa is also input to the dot forming circuit 4, to trigger 
a pattern memory controller 41 there to read a halftone dot pattern signal 
from a pattern memory 42. In a comparing circuit 3, the controller 41 
compares the dot pattern with the graphic data D.sub.1 output from 
interface 5, and outputs a control signal Sb.sub.1 to turn on or off the 
beams to the graphic output head 1 as is shown in FIG. 8. 
Methods for producing a halftone image directly from a graphic signal which 
has graduated tone are disclosed in U.S. Pat. No. 3,725,574 and U.S. 
patent application Ser. No. 365,890 (British Patent Application No. 
8208940 Publication No. 2098022). Accordingly, a detailed explanation of 
the methods is omitted from the present description. The circuit in FIG. 8 
is operable for controlling one beam. Accordingly, in a practical circuit 
there are provided ten similar circuits in all. 
On the other hand, the literal data input from the literal memory 12 to a 
line buffer memory 71 of an interface 7 on command of the CPU 15 are 
converted into literal raster data D.sub.2 in an external changeover 
circuit (not shown in the figures) referring to the front data stored in 
the literal font memory 13. The data D.sub.2 are then rearranged to be 
utilized for output from the output head of the beam producer from which 
emanate two or three beams simultaneously. Furthermore, the rearranged 
data D.sub.2 are read in synchronism with the literal timing pulse Pb from 
the line buffer memory 71. 
Thus, literal raster data D.sub.2 read from the line buffer memory 71 are 
then input to an output line changeover circuit 72 which changes the 
number of data lines according to the number of beam components to be used 
in the literal output head 2. 
That is, as the literal output head 2 changes the number of the beam 
components to be used (between two and three beams) every revolution of 
the recording drum 20, the number of data lines must be changed in 
synchronism with the revolution pulse Pm (every revolution of the 
recording drum 20) according to the number of beam components utilized. 
Furthermore, thus rearranged literal data of the appropriate number of 
lines are input as a beam driving signal Sb.sub.2 via a driving amplifier 
73 to a literal output driving circuit 3. 
In this manner, a graphic recording beam B.sub.1 and a literal recording 
beam B.sub.2 are generated from their respective beam producers at the 
same time, upon command of said control signals Sb.sub.1, Sb.sub.2, to 
record a complete reproduced image, having both graphic and literal 
components, on a film or other recording medium. 
In the described embodiment, when the screen ruling has to be changed 
according to an input request, such a procedure can be easily performed 
with a zoom lens as the image formation lens 17 of the picture output head 
1 (or with a selected one of a plurality of lenses, each of which has a 
distinct magnification) by varying the screen ruling according to the 
magnification of the lenses. To synthesize the feeding pitches of the 
literal and graphic heads, two methods can be adopted. One of the methods 
is to vary the number of beam components of the literal output head and to 
adjust length according to the magnification of an employed lens. The 
other is to employ a zoom lens as an imaging lens 18 for the literal 
output head, the magnification of which is equivalent to that of the 
graphic output head 1. When various numbers of screen rulings are used and 
the differences between them are considerable, the number of beam 
components of the literal output head should be increased beforehand, 
while if a fine screen ruling is used (i.e., narrow screen line width), 
the number of beam components actually used in the scan may be reduced, 
i.e., deactivated. 
The procedure of varying the number of screen rulings can also be attained 
by changing the number of beam components of the graphic output head 1. 
In this case, the number of screen rulings can be varied by changing the 
number of beam components of the graphic output head 1, which also 
requires a corresponding change of the number of beam components of the 
literal output head 2. 
Assuming that the number of beam components of the graphic output head 1 is 
six, (the diameter of each beam component is 1/4000 inch), two times the 
sub-scanning length of the grahic output head 1 is 6/4000+6/4000=3/1000 
inch. Thus, in two scans a 3/1000 inch segment is reproduced. Assuming 
that the diameter of each beam component of the literal output head 2 is 
1/1000 inch, the graphic and literal heads can be synchronized in the 
sub-scanning direction by using two beam components of the literal output 
head in a first scan and by using a single beam component of the literal 
output head during the second scan. 
In the above embodiment, the same result can be attained by selectively 
using a proper number of beam components of the graphic output head 1. 
However, in order to secure uniformity of halftone dots (for recording 
picture components), it is preferable to increase or decrease the number 
of beam components of the literal output head rather than using such a 
procedure on the beam components of the graphic output head. 
As mentioned above, the thrust of the present invention is to synchronize 
the feeding pitches of a graphic output head and a literal output head in 
the sub-scanning direction to record graphic and literal components 
simultaneously by changing scan length of at least one of the recording 
heads. Preferably, this feature is attained by changing the number of beam 
components of the literal head after scanning a predetermined number of 
scanning lines when an image reproducing procedure is performed with the 
graphic and literal output heads, which each have a respective set of beam 
components including a particular number and diameter of such components. 
Therefore, the present invention has an advantage of easily recording 
graphic and literal components simultaneously, even when the screen ruling 
is required to be varied, which has proved troublesome to implement in the 
prior art. 
The foregoing description of the preferred embodiment of the invention has 
been presented for purposes of illustration and description, and is not 
intended to be exhaustive or to limit the invention to the precise form 
disclosed, since many obvious modifications and variations are possible in 
light of the above teaching. The embodiment was chosen and described in 
order best to explain the principles of the invention and its practical 
application, thereby to enable others skilled in the art best to utilize 
the invention in various embodiments with various modifications as are 
suited to the particular use contemplated. It is intended that the scope 
of the invention be defined by the claims appended hereto, when 
interpreted in accordance with the full breadth to which they are fairly 
and legally entitled.