Color optical scanner with single linear array

An optical scanning device is disclosed that generates data representative of a color image of an object using only one linear photosensor array. Image data corresponding to two or more color components is collected by making multiple incremental, reciprocal displacements of a scanning head with a different filter or other color selection mechanism in place during different incremental displacements. By traversing the scanned object in a series of reciprocal movements, color component data corresponding to relatively small portions of the scanned object is sequentially collected in and then removed from dynamic memory. As this data from each path segment is removed from dynamic memory, it is processed to place it in a correlated form representative of a polychromatic image of that path segment and is then stored in an ordered array in another, typically longer term, memory device such as a hard disk.

BACKGROUND OF THE INVENTION 
The present invention relates generally to color optical scanners and, more 
particularly to color optical scanners which employ a single line optical 
sensor array. 
Color optical scanners are similar to black and white and gray scale 
optical scanners in that data representative of a scanned document 
(object) is produced by projecting an image of the scanned document onto 
an optical sensor. The optical sensor includes a plurality of cells or 
"pixels" which produce data signals representative of the intensity of the 
light impinged thereon. These data signals are typically digitized and 
stored on appropriate data storage media. Such stored data may later be 
used, as for example through a personal computer and computer monitor, to 
produce a display image of the scanned object. The image of the scanned 
object is projected onto the optical photosensor array incrementally by 
use of a moving scan line. The moving scan line is produced either by 
moving the document with respect to the scanner optical assembly or by 
moving the scanner optical assembly relative to the document. 
In a stationary flat bed scanner, an object to be scanned, usually a paper 
document, is placed on a transparent plate. A scan bar is moved underneath 
the plate and document. The scan bar is associated with an optical system 
that focuses light from the document onto a row or "linear array" of 
optical sensors. The scan bar often includes a light source which 
illuminates the object. At any given time, one line across the width of 
the document which is spanned by the scan bar is imaged on the row of 
sensors. This line is referred to herein as a "scan line" or "object scan 
line", and it is moved along the length of the object as the scan bar 
moves. 
The object scan line comprises a plurality of "object pixels" or simply 
"pixels" which correspond to the pixels on the optical sensor. 
In a moving flat bed scanner, an object is again placed upon a transparent 
plate and a scan bar is positioned below the plate and object. However, in 
this type scanner, the scan bar remains stationary and the plate and the 
object supported on it are moved in order to move the scan line across the 
document. 
Another type of scanner is a scroll feed scanner. In this scanner design, 
the scan bar remains stationary while a system of mechanical rollers moves 
the document to be scanned past the scan bar. 
Finally, some stationary flat bed scanners have a scroll feed automatic 
document feeder option such as that described in U.S. Patent application 
Ser. No. 902,638 filed Jun. 23, 1992 for SHEET FEEDING APATUS FOR 
FLATBED OPTICAL SCANNERS of J. Bybee, now U.S. Pat. No. 5,232,216 which is 
hereby specifically incorporated by reference for all that it discloses. 
When the automatic document feeder option is used, the scan bar moves to a 
precisely defined location under the document feeder and remains 
stationary. During scanning, the document feeder moves the document past 
the scan bar in the same manner as a scroll feed scanner. 
Color optical scanners differ from black and white scanners in that 
multiple color component images of an object must be collected and stored 
to produce a color display image of the object. Typically data 
representative of red, green and blue component color images of the 
scanned object are produced and correlated for storage. 
Various techniques are used in color optical scanners for collecting data 
representative of multiple component color images. 
One technique, such as described in Vincent, U.S. Pat. No. 4,709,144 and 
Boyd, et al., U.S. Pat. No. 4,926,041, which are both hereby specifically 
incorporated by reference for all that is disclosed therein, is to split a 
polychromatic scan line light beam into multiple color component beams 
which are projected onto multiple linear photosensor arrays. For example 
an imaging beam from the same narrow scan line region of a document is 
split into red, green and blue component beams which are then 
simultaneously projected onto separate linear photosensor arrays. Using 
this technique the component color image data generated from any 
particular scan line is generated simultaneously and is thus easily stored 
in a correlated form. 
Another technique for generating multiple color component images from a 
polychromatic light beam is to simultaneously project light from different 
scan line regions of a document onto separate linear photosensor arrays 
such as described in Takeuchi, R. et al. (1986) "Color Image Scanner with 
an RGB Linear Image Sensor," SPSE Conference, The Third International 
Congress On Advances in Non-Impact Printing Technologies, PP339-346, 
August 1986, which is hereby specifically incorporated by reference for 
all that it discloses. Using this technique it is necessary to perform 
data manipulation to correlate the data representative of different scan 
line component images since the different component color images of any 
scan line region of the document are generated at different times. A 
variation on this technique which allows image scaling is described in 
U.S. Patent application, Ser. No. 08/060,289 filed May 10, 1993 for 
VARIABLE SPEED SINGLE PASS COLOR OPTICAL SCANNER of Boyd and Degi, now 
U.S. Pat. No. 5,336,878 which is hereby incorporated by reference for all 
that it discloses. 
Another scanning technique is to project imaging light onto a single linear 
sensor array during multiple scanning passes using differently colored 
illumination sources. For example a document is first scanned using only 
red light, then only green light and finally only blue light. In a 
variation of this technique three scanning passes are made using a white 
light illumination source but the imaging light is filtered before it 
enters the sensor array with a different color filter during each of the 
three passes. 
One cost saving advantage of such a multiple pass color optical scanner is 
that is requires only a single linear sensor array rather than the 
multiple linear sensor arrays used in some scanning techniques. However, a 
disadvantage of this technique is that a computer receiving the digitized 
data from the scanner must store all of the data from at least two of the 
scanning passes before it can begin assembling the color component data 
and processing it. Thus, this technique usually requires a relatively long 
period of time to generate the combined data representative of a color 
image because of the data processing time needed to assemble the color 
component data after the last scanning pass. Also, this technique requires 
a large amount of buffer memory in the computer which performs the image 
data processing or, alternatively requires buffer storage to be provided 
on an associated disk drive which further increases the processing time. 
Another disadvantage of the three pass color scanning technique is that it 
is usually impractical for scroll feed scanning. This is because the 
object which is scanned, usually a paper document, must be scroll fed past 
a stationary scan bar three times. It is necessary for the scan lines on 
each pass to coincide and thus, the position of the document must be 
precisely repeated for each pass. This is extremely difficult to 
accomplish in a scroll feed assembly due to inherent slippage between the 
document and feeder which may occur during initial document positioning 
and during the scanning pass movement. 
Various types of photosensor devices may be used in optical scanners. 
Currently the most commonly used photosensor device for optical scanners 
is the charge coupled photosensor device or "CCD". A CCD builds up an 
electrical charge in response to exposure to light for a preset period of 
time known as a sampling interval. The size of the electrical charge built 
up is dependent on the intensity and the duration of the light exposure 
during the sampling interval. 
In optical scanners CCD cells are aligned in linear arrays. Each cell or 
"pixel" has a portion of a scan line image impinged thereon as the scan 
line sweeps across the scanned object. The charge built up in each of the 
pixels is measured and then discharged at the end of each sampling 
interval. In most optical scanners the sampling intervals of the CCD 
arrays are fixed. A typical CCD sampling interval is 4.5 milliseconds. 
As previously mentioned, an image of the scan line which moves across a 
scanned document is projected onto the scanner's linear sensor array by 
scanner optics. The scanner optics usually comprise an imaging lens which 
typically reduces the size of the imaged scan line from that of the object 
scan line considerably, e.g. by a ratio of 7.9:1. 
As used herein, "imaged scan line" or "image scan line" refers to the image 
of the object scan line which is projected onto the linear photosensor. 
Both the imaged scan line and the object scan line are often referred to 
in the industry as simply "scan line". 
SUMMARY OF THE INVENTION 
The present invention is directed generally to a color optical scanning 
device which enables multiple pass color optical scanning to be 
efficiently accomplished without the need for an extensive amount of 
buffer memory. 
To accomplish this multiple pass scanning, an object, such as a document, 
is divided into segments and scanned in a series of reciprocal movements. 
Each movement acquires one monochrome component of the color image of one 
of the segments. The data for each monochrome component is stored in a 
dynamic or buffer memory. When all of the monochrome components for a 
segment have been acquired, they are then correlated and stored in array 
form to represent the color image of that particular segment. This 
correlated data may then be stored in a separate, longer term memory 
device such as a hard disk thus freeing up the buffer memory to receive 
color component data from the next segment. The process is then repeated 
for each segment of the object. 
Using this technique, only enough buffer memory need be provided to store 
image data from one segment, rather than from the entire document. 
Accordingly, a method and apparatus are provided which overcome the 
previously described disadvantages regarding slow processing times and 
large buffer memory storage requirements. 
The color optical scanning device may acquire image data only during one 
direction of reciprocal movement, or it may acquire data in both 
directions. The device may be a stationary flat bed type scanner, a moving 
flat bed type scanner, a scroll feed type scanner or a stationary flat bed 
type scanner having a scroll feed automatic document feeder as previously 
described.

DETAILED DESCRIPTION OF THE INVENTION IN GENERAL 
FIGS. 6 and 7 illustrate, schematically, the general construction and 
operation of a color optical scanner device 10 for generating data, from 
imaging light 19 that is imaged on a photosensor array 24, which is 
representative of a color image of a scanned object 14. A plurality of 
band portions or segments 91, 92, 93, etc. are defined along the length of 
a scanning path. A scan line displacement assembly 46 is provided which 
may include a photosensor array 24 and an imaging assembly 18 such as a 
lens which defines an imaging light path 56 arranged between a scanned 
object 14 and the photosensor array 24. A color selection mechanism 31, 
such as a filter plate, is located within the light path 56. The scan line 
assembly 46 is movable along the scanning path in a series of reciprocal 
movements within each segment 91, 92, 93, etc. 
In operation, the color optical scanner device 10 generates data from 
imaging light 19 imaged on the photosensor array 24 representative of a 
color image of the scanned object 14 by displacing a scan line 13 from a 
first end 15 to a second end 17 of a scanning path. The scan line is 
displaced in a plurality of reciprocal movements in each of the plurality 
of segments 91, 92, 93, etc. of the scanning path. The color of the 
imaging light 19 which is imaged on the photosensor array 24 is changed in 
accordance with the reciprocal movements. 
Having thus described the color optical scanner device 10 of the present 
invention in general, certain exemplary structure of one embodiment of an 
optical scanner 10 will now be described in detail. 
SCANNER STRUCTURE 
FIGS. 1-3 and 7 illustrate a stationary, flat bed optical scanner device 10 
which is adapted for producing machine readable data representative of a 
color image of a scanned object 14 such as a sheet of paper with graphics 
provided thereon as illustrated in FIG. 6. The object 14 which is to be 
scanned may be supported on a transparent plate 12 located on the upper 
panel of the scanner device. The scanner device includes a light source 
assembly 16 for illuminating object 14 and also includes an imaging 
assembly 18, such as a conventional scanner lens assembly, (shown 
schematically in FIG. 7) for focusing imaging light 19 from scan line 13 
on object 14 onto a linear photosensor array 24 of a photosensor assembly 
20 so as to provide an image 11, FIG. 4, of the scan line 13 portion of 
the object on the photosensor array 24. 
The photosensor assembly 20 of the scanner device operates in successive 
sampling intervals and generates image data representative of the scan 
line images which are successively focused on associated photosensor array 
24. The photosensor assembly 20 may be a CCD photosensor unit. As 
illustrated by FIGS. 4 and 5, the photosensor assembly 20 includes a 
linear photosensor 24 having a predetermined photosensor line width (pixel 
width), e.g. 8 microns (0.000315 inches), which is located at the focus of 
the imaging assembly 18 (which in one preferred embodiment is a planar 
region) and which generates a data signal representative of the intensity 
of imaging light 19 which is impinged thereon. 
First, second and third color filters 34, 36, 38 on a filter plate 31 may 
be mounted on the arm 35 of a reciprocal actuator 33 for movement in 
directions 37. The filters are operably associated with the linear 
photosensor 24 for filtering imaging light focused on the linear 
photosensor in successive intervals such that the linear photosensor 24 
receives only light of a first preselected color, e.g. red, during a first 
filter period in which first filter 34 is opposite linear array 24, 
receives only light of a second selected color, e.g. green during a second 
filter period in which filter 36 is opposite array 24; and receives only 
light of a third preselected color, e.g. blue during a third filtering 
period, during which filter 38 is opposite array 24. 
The scanner may also be operated in black and white or gray scale modes 
during which plate 31 is not in covering relationship with linear 
photosensor array 24, as shown in FIG. 4. 
When operating in the black and white or gray scale modes with the filter 
plate displaced from the photosensor array 24, the array 24 receives 
approximately three times as much imaging light as it does when covered 
with one of the red, green, or blue filters. As a result, the scanner may 
be operated to acquire data about three times as fast in the black and 
white or gray scale operating modes as in the color operating mode. This 
increased speed of operation in the black and white or gray scale modes is 
one significant advantage of the present scanner design over most 
conventional color optical scanners. 
The photosensor assembly 20 and associated filters 34, 36, 38 may be of a 
type identical to that described in detail in U.S. patent application, 
Ser. No. 869,273, of Michael John Steinle and Steven Lawrance Webb for 
COLOR IMAGE SENSING ASSEMBLY WITH MULTIPLE LINEAR SENSORS AND ALIGNED 
FILTERS filed Apr. 15, 1992, now U.S. Pat. No. 5,300,767, which is hereby 
specifically incorporated by reference for all that it discloses, except 
that the photosensor assembly 20 has only a single linear array. 
The optical scanner device 10 may include a displacement assembly 40, FIG. 
2, which includes a drive motor 42, a drive belt 44 and a carriage 
assembly 46. The drive motor 42 is adapted to drive the carriage assembly 
46 in a series of short reciprocal movements as it progressively moves 
from one end of plate 12 to the other as described in further detail 
below. 
The carriage assembly 46 may support light source 16, FIG. 3, imaging 
assembly 18 and photosensor assembly 20, FIG. 7, therewithin. The carriage 
assembly 46 may also support a light slit 48 defining structure 49, FIG. 
3. The light slit defining structure 49 may also support the light source 
16 which may comprise a pair of fluorescent bulbs. The light slit 48 is 
sufficiently wide to provide an image 11 at least as wide as linear 
photosensor array 24. A plurality of mirrors 50, 52, 54 may also be 
provided within the carriage assembly so as to provide a folded imaging 
light path 56 (shown schematically as a linear path in FIG. 7) extending 
from the currently scanned portion 13, FIGS. 3, 6 and 7, of the object 14; 
through the light slit 48; thence from mirror 50 to mirror 52 to mirror 
54, and thence, through imaging assembly 18 to photosensor assembly 20. 
Photosensor assembly 20 may be provided within a shroud member 58 
supported by the carriage assembly 46, FIG. 3. 
The carriage assembly 46 is displaced relative to transparent plate 12, and 
the object 14 supported thereon, to produce a sweeping scan image of the 
object at the linear photosensor 24. Thus, in this embodiment, the 
carriage assembly acts as a scan line displacement assembly which moves 
scan line 13 from one end 15 of object 14 to the other end 17, FIG. 6. The 
carriage assembly 46 progresses in a primary scan direction 43 through a 
series of reciprocating movements in both primary scan direction 43 and 
secondary (reverse) scan direction 45 as described in further detail 
below. 
CONTROL SYSTEM 
As illustrated in FIG. 7, the control system for the scanner device 
includes a data processor 74 which receives inputs from various components 
of the optical scanner, processes these inputs, and provides output 
commands to various operating components of the scanner as will be 
described in further detail below. 
The processing performed by the data processor 74 may be performed through 
the use of hard-wired electronic components, or through the use of a 
computer and associated computer programs provided in software or firm 
ware, or may be processed by using a combination of such data processing 
techniques. The data processor 74 receives an input signal from a scan 
line displacement sensor 76 which is indicative of the displacement of 
scan line 13 across the scanned object 14 in both a primary scanning 
direction 43 and secondary scanning direction 45. 
The scan line displacement sensor 76 may comprise a conventional optical 
encoder unit mounted on a shaft of the scan line displacement assembly 
drive motor 42 which provides a displacement signal consisting of a 
plurality of motor encoder pulses 151, 152, etc., FIG. 8, which are 
representative of units of displacement of the scan line 13 across 
document 14. In a typical embodiment, each encoder pulse 151, 152 might 
represent a distance of scan line displacement of about 1/600 of an inch. 
Alternatively, the scan line displacement sensor may comprise an optical 
sensor unit 39, FIG. 7, that is mounted on the carriage assembly 46 and 
which provides a displacement signal based upon the detection of a 
plurality of marks such as the marks 161, 162 schematically illustrated in 
FIG. 6. These marks may be located on any stationary surface of the 
scanner device, such as the bottom of transparent plate 12. Photodetectors 
for detecting registration marks are well known in the art. A separate 
photodetector may be used as the registration mark sensor 39 or 
alternatively an end portion of linear photosensor 24 may be used for 
detecting registration marks. 
The data processor 74 may also receive an input signal from a filter 
displacement sensor 82 which is indicative of the position of filter plate 
31 and is thus indicative of the particular color filter 34, 36 or 38, 
FIGS. 4 and 5, which is currently positioned opposite the linear 
photosensor array 24. 
The data processor 74 also receives a data signal from the photosensor 
array 24 which is indicative of the color component image which has been 
focused on the linear photosensor array 24 by the imaging assembly 18. 
Prior to processing by data processor 74, the information in the data 
signal from the photosensor array 24 is stored in the dynamic memory 73, 
typically random access memory, which may be an integral component of the 
data processor or may be a separate memory device such as an operably 
connected RAM integrated circuit. The data processor 74 may be the data 
processor of a connected personal computer, such as an Intel Pentium chip 
based computer, or may be a separate dedicated data processor provided on 
the scanner. 
The data processor 74 processes the various inputs as will be described in 
further detail below and provides output command signals in response 
thereto to control the operation of various scanner components. The data 
processor 74 provides a control signal to the scan line displacement 
assembly drive motor 42 to control the displacement of scan line 13 across 
document 14. The data processor also provides a control signal to filter 
actuator 33 to control the color filter which is currently positioned 
opposite the photosensor array 24. The data processor 74 also provides a 
control signal to the photosensor assembly 20 to initiate data collection 
from each band portion 91, 92, 93, etc. of the document, FIG. 6, as 
described in further detail below. 
The operation of the control system in one embodiment of the invention in 
which data input from the document takes place only when the scan line 13 
is moving in the primary scan direction 43 will now described with 
reference to FIGS. 8-11B. 
FIGS. 11A and 11B describe, in general, an operation in which the scan line 
13 is displaced across a series of adjacent band portions (also referred 
to herein as segments) such as 91, 92, 93 of the object 14 in a number of 
reciprocal scanning cycles which is equal in number to the number of color 
component images which are to be generated. Most color optical scanners 
generate only three component images of an object which is scanned because 
only three such images are necessary to produce a polychromatic image of 
an object. (Nevertheless, it is to be understood that, although an 
embodiment which generates only three color component sets of data is 
described herein, the invention is not to be limited to a three-component 
color optical scanner and includes an optical scanner which generates only 
two color component images as well as an optical scanner which generates 
four or more color component images.) 
The data processor 74 next generates commands to displace the scan line 13 
across a band portion in the primary scan direction 43 during a first 
color component scan of the band region, e.g., a red color component scan 
as indicated by the reference numeral "43R1" in FIG. 8. The data processor 
74 initially actuates the filter actuator 33 to move the red filter 
portion 34 of the plate over the photosensor array 24. The data processor 
74 also actuates the photosensor assembly 20 at the beginning of the red 
component scan and thus, the photosensor assembly 20 generates image data 
representative of a red color component image of band region 91. 
Band region 91 has a width which is typically more than one scan line 
width, but less than the width of the entire document. A region on the 
document which is one scan line wide is referred to herein as a "scan line 
portion of an object" or simply as a "scan line" or "line". (It is to be 
understood that "scan line" when used in this sense, represents a fixed 
area on the document as opposed to a moving illuminated portion of the 
document which is currently being imaged on the linear photosensor array 
which is also referred to herein and in the art as a "scan line".) In the 
schematic embodiments of FIGS. 6 and 8-10, each band portion 91, 92, 93, 
etc. is indicated to be six scan lines wide, e.g., the band 91 contains 
the six scan lines 101, 102, 103, 104, 105, 106. Band 91 is located 
between reference numerals 112 and 116 in FIG. 8. The next band 92 
contains the next six scan lines on the document, located between 
reference numerals 122 and 124 in FIG. 8. The next band contains the next 
six scan lines on the document, etc. It is to be understood that this 
number of scan lines has been chosen for illustrative purposes. In a more 
typical example, there could be 50 scan lines each having a scan line 
width of 1/300 of an inch in each band 91, 92, 93. 
At the beginning of the red sweep 43R1, the scan line 13 is positioned at a 
location indicated by reference numeral 110 in FIG. 8. The scan line 13 is 
initially positioned at a point before the beginning of first band region 
91 to allow for initial acceleration of the scan head to ensure that the 
entire band region 91 is scanned at the same scanning velocity. 
As the scan line 13 moves across the first band region 91 in its red pass, 
as indicated at 43R1, it sends data to a dynamic memory device 73 which 
stores the data in an array ordered by scan line and the pixels in each 
scan line. This ordered data array may be envisioned as a plane containing 
scan lines ordered in rows and pixels ordered in columns and including all 
red component image data as illustrated by the first plane in FIG. 9. 
At the end of the red sweep indicated at 43R1, the scan line has moved 
slightly past the first band portion of the object to a location indicated 
by reference numeral 114 in FIG. 8. The first band region is scanned at a 
constant scanning velocity and this "over shoot" of the first band region 
occurs as the scan head is decelerating after passing over the entire 
first band region. 
The scan bar is next moved in the secondary scanning direction 45, i.e., 
the direction opposite direction 43, until it is returned to the position 
110 which it occupied at the beginning of the 43R1 scan sweep. No data is 
collected during movement in direction 45 and thus, in one preferred 
embodiment of the invention, photosensor array 24 is de-actuated during 
the movement in direction 45. Alternatively, photosensor array 24 may 
continue to operate but the data stream therefrom is controlled in a 
manner such that it does not enter dynamic memory 73. 
Next, the green filter plate portion 36 is moved into position over 
photosensor array 24 and the photosensor assembly 20 is again actuated or 
the data stream therefrom is re-connected to dynamic memory 73 such that 
data is collected during a green scanning pass as indicated at 43G1 in 
FIG. 8. Green scanning pass 43G1 is identical to the red pass except for 
the fact that a green filter 36 rather than a red filter 34 is positioned 
over the linear photosensor array. At the end of the green pass, the scan 
line 13 is again returned to the starting point 110 and a blue pass, which 
is identical to the red pass and the green pass except for the color of 
the filter, is initiated. 
At the end of the blue pass, the displacement of the scan line is stopped. 
Rather than being returned to the beginning of the first band portion, 
however, scan line 13 it is only moved back a small distance such that it 
is positioned at a location 120 in front of the second band portion 92. 
The locations of the scan line 13, the band region scan line starting and 
stopping points (e.g., 110, 114, 120, 126, FIG. 8) and the band region 
beginning and ending points (e.g., 112, 116, 122, 124, FIG. 8) are 
determined by monitoring the encoder pulses such as the encoder pulses 
151, 152, etc. shown schematically in FIG. 8. The encoder resolution is 
preferably selected such that each scan line 101, 102, 103, 104, 105, 106, 
etc. is multiple, e.g., 10 encoder pulses wide. 
As previously mentioned, rather than using a drive motor mounted encoder 
76, a register mark sensor 39 which senses register marks 161, 162, etc., 
FIG. 6, associated with the scanned object 14 may be used for determining 
the beginning and end of each band region. Or, more preferably, a 
combination of register mark sensing and encoder pulse counting could be 
used. For example, movement of the scan line could be stopped a 
predetermined number of encoder pulses after the sensing of register marks 
defining the beginning and end of each band portion. Many other triggering 
arrangements for controlling scan bar displacement might also be employed 
and are within the scope of the invention. 
Similarly, methods for determining scan line displacement other than 
counting of encoder pulses could be employed. For example, rather than 
using a closed loop system as illustrated in FIG. 6, an open loop system 
could be adopted by using a stepper motor to drive the scan line 
displacement assembly 46. In such a system, a control command from the 
data processor dictates the number of "steps" which the stepper motor is 
to move to achieve a desired displacement of the scan line displacement 
assembly and the appropriate number of current pulses are generated to 
move the motor through the required number of steps. No feedback from the 
stepper motor to the data processor 74 is required. 
At the end of the three color passes 43R1, 43G1, 43B1, data from the six 
scan lines in band 91 will have been stored in memory in three separate 
arrays with the red data stored in a first array, the green data stored in 
a second array, and the blue data stored in a third array as represented 
schematically by the three planes in FIG. 9, with "Line 0" indicating the 
data from line 101, "Line 1" representing data from line 102, etc. 
Once the three colored sweeps of the first band have been completed, the 
data processor 74 begins processing the data illustrated schematically in 
FIG. 9 such that the red, green and blue data from each pixel in each scan 
line is correlated as shown in FIG. 10. This correlated data is then 
stored in another memory device 75 and the dynamic memory 74 is free to 
receive data from the next band portion 92 of the object 14. 
Referring again to FIG. 8, after completion of the blue scan indicated at 
43B1, the scan line is displaced in direction 45 to a position 120 just 
before the beginning of the second band 92 and the above described 
sequence is then repeated for the second band 92. This same sequence is 
repeated through each of the remaining bands in the scan path until 
reaching the end 17, FIG. 6, of the scan path at which point the scan is 
complete and data representative of a color component image of the entire 
object 14 has been collected and stored in data storage as indicated at 75 
in FIG. 7. The data storage device 75 may comprise, for example, a floppy 
disk, a hard disk, an optical disk or any other desired storage device. 
The operation of the control system in another embodiment of the invention 
in which data input from the document takes place when the scan line 13 is 
moving in both the primary scan direction 43 and the secondary scan 
direction 45 will now described with reference to FIGS. 12-13B. 
FIGS. 13A and 13B describe, in general, an operation in which the scan line 
13 is displaced across a series of adjacent band portions 91, 92, 93 of 
the object 14 in a number of reciprocal scanning cycles which is equal in 
number to the number of color component images which are to be generated. 
The data processor 74, FIG. 7, generates commands to motor 42 to displace 
the scan line 13 across a band portion 91 in the primary scan direction 43 
during a first color component scan of the band region, e.g., a red color 
component scan as indicated by the reference numeral "43R1" in FIG. 12. 
Prior to the commencement of this color component scan indicated at 
"43R1", the data processor 74 actuates the filter actuator 33 to move the 
red filter portion 34 of the plate over the photosensor array 24, FIGS. 5 
and 6. The data processor 74 also actuates the photosensor assembly 20 at 
the beginning of the red component scan and thus, the photosensor assembly 
20 generates image data representative of a red color component image of 
band region 91. 
At the beginning of the red sweep 43R1, the scan line 13 is positioned at a 
location indicated by reference numeral 130 in FIG. 12. The scan line 13 
is initially positioned at a point before the beginning of first band 
region 91 to ensure that the scan line displacement assembly has 
accelerated to a constant scanning velocity before band region 91 is 
scanned. 
As the scan line 13 moves across the first band region 91 in its red pass, 
as indicated at 43R1, it sends data to a dynamic memory device 74 which 
stores the data in an ordered array ordered by scan line and the pixels in 
each scan line in a manner as described previously with reference to FIG. 
9 
At the end of the red sweep indicated at 43R1, the scan line has moved past 
the first band portion of the object 134 to a location indicated by 
reference numeral 135 in FIG. 12. 
Next, the green filter plate portion 36 is moved into position over 
photosensor array 24 and the photosensor assembly 20 is actuated such that 
data is collected during a green scanning pass as indicated at 43G1 in 
FIG. 8. Green scanning pass 43G1 is identical to the red pass except for 
the fact that a green filter rather than a red filter is positioned over 
the linear photosensor array and the scan line 13 is moving in the 
opposite direction as indicated by the arrow 43G1. At the end of the green 
pass, the scan line 13 has again returned to the starting point 130 and a 
blue pass, which is identical to the red pass except for the color of the 
filter, is initiated. 
At the end of the blue pass, the displacement of the scan line is stopped. 
The scan line 13 is then moved back a small distance such that it is 
positioned at a location 133 in front of the second band portion 92. 
At the end of the three color passes 43R1, 43G1, 43B1, data from the six 
scan lines in band 91 will have been stored in memory in three separate 
arrays with the red data stored in a first array, the green data stored in 
a second array, and the third data stored in a third array as represented 
schematically by the three planes in FIG. 9. 
Once the three colored sweeps of the first band have been completed, the 
data processor 74 begins processing the data illustrated schematically in 
FIG. 9 such that the red, green and blue data from each pixel in each scan 
line is correlated. This correlated data is then stored in another memory 
device 75 and the dynamic memory 74 is free to receive data from the next 
band portion 92 of the object 14. 
Referring again to FIG. 12, after completion of the blue scan indicated at 
43B1, the scan line is displaced in direction 45 to a position 133 just 
before the beginning of the second band 92 extending from 134 to 136 and 
the above described sequence is then repeated for the second band 92 with 
back and forth sweeping movement between 133 and 137. This same sequence 
is repeated through each of the remaining bands 93, etc. in the scan path 
until reaching the end 17 of the scan path at which point the scan is 
complete and data representative of a color component image of the entire 
object 14 has been collected and stored in data storage as indicated at 75 
in FIG. 7. 
As can be appreciated, in this embodiment of the invention, less physical 
movement of scan line 13 is required to scan a document or other object. 
This allows for an overall faster scan time. However, in this embodiment, 
backlash and slippage in the drive motor and other mechanical components 
of the scan line displacement assembly make identical registration between 
each of the color scans of a particular band problematic, i.e., scans made 
in a primary scan direction 43 may not be in proper registration with 
scans made in secondary registration direction 45 unless registration mark 
sensing is used to establish a boxed reference position, particularly in 
an open loop system. Thus, in embodiments where scanning takes place in 
both directions 43, 45, it is particularly desirable to employ a 
registration mark sensor 39 to determine the beginning and end of each 
band, e.g., 92 which is being scanned. 
The optical scanner device 10 has so far been described with respect to a 
scanning device in which the object to be scanned 14 remains stationary 
and the scan bar moves to acquire the image data. The optical scanner 
device previously described may, however, alternatively be used with a 
scroll feed type scanner in which the scan bar remains stationary while a 
system of mechanical rollers moves the document to be scanned past the 
scan bar. 
The control system for the optical scanner device used with a scroll feed 
type scanner is schematically illustrated in FIG. 14. FIG. 14 is, in most 
respects, identical to FIG. 7 which has been previously described with 
respect to the moving scan bar scanner device. In the scroll feed control 
system of FIG. 14, however, the scan line displacement assembly drive 
motor 42 and the scan line displacement sensor 76 of FIG. 7 have been 
adapted for the scroll feed type scanner as will now be described. 
Referring to FIG. 14, a wheel 170 may be attached to the paper feed roller 
172 of a scroll feed type scanner. Feed roller 172 is used to feed the 
document or other object 14 to be scanned into the scanning device and 
past the scan line 13. The wheel 170 is mounted for rotation about the 
axis 174 along with the roller 172. A series of indicia marks such as 176, 
178 and 180 are provided on the outer surface of wheel 170. 
An indicia sensor 182 is located so as to sense the indicia 176, 178, 180, 
etc. as the roller 172 and wheel 170 turn. As the wheel 170 turns, the 
indicia sensor 182 sends a signal to the data processor 74 indicative of 
the amount of rotation of wheel 170 and roller 172. Since the 
circumference of the roller 172 is known, the signal from the sensor 182 
can be directly correlated to the location of the document 14 with respect 
to the scan line 13. 
As shown schematically in FIG. 14, the roller 172 is driven by drive motor 
184. Drive motor 184, in turn, is controlled by a signal from 
microprocessor 74. A drive motor encoder 185 may also be provided for 
generating a motor displacement signal which may have a finer resolution 
than indicia sensor 182 and which is used in combination with the indicia 
sensor signal for precisely controlling scroll feed displacement. 
Accordingly, the scanning motions previously described with respect to the 
moving scan line may be accomplished by moving the roller 172 and, thus 
the document 14, in a scroll feed type scanner. 
The previously described optical scanner device 10 may also be used with a 
moving flat bed type scanner. As previously described, in a moving flat 
bed scanner, an object is placed on a transparent plate and a scan bar is 
positioned below the plate and object. In this type of scanner, the scan 
bar remains stationary and the plate and the object supported on it are 
moved in order to move the scan line across the document. 
To use the previously described optical scanner device 10 with a moving 
flat bed scanner, a system as shown in FIG. 7 may be employed. Sensor 76 
may be attached to any of the rotating drive mechanisms associated with 
the moving bed of the moving flat bed scanner and/or register mark sensor 
39 may be stationarily positioned below the moving bed. In this manner, 
signals may be sent to microprocessor 74 which are indicative of the 
relative displacement between the moving bed and the stationary scan bar. 
The previously described optical scanner device 10 may also be used with a 
stationary flat bed scanner which has a scroll feed automatic document 
feeder option as previously described. When such an automatic document 
feeder option is used, the scan bar moves to a precisely defined location 
under the document feeder and remains stationary. During scanning, the 
document feeder moves the document past the scan bar in the same manner as 
a scroll feed scanner. 
In such a device, the motions described previously may be accomplished by a 
combination of the movement of the paper by the automatic document feeder 
and the movement of the scan bar. For example, the back and forth 
reciprocal motion previously described could be accomplished by moving the 
feed wheel back and forth. Alternatively, the reciprocal motion could be 
accomplished by the moving scan bar while the feed wheel moves in only one 
direction to advance the document. 
It is contemplated that the inventive concepts herein described may be 
variously otherwise embodied and it is intended that the appended claims 
be construed to include alternative embodiments of the invention except 
insofar as limited by the prior art.