 |
Description  |
|
|
BACKGROUND OF THE INVENTION
The present invention generally relates to an image reading apparatus, and
more particularly, to an image reading apparatus provided with an
enlarging or magnifying function.
Commonly, in a digital copying apparatus, digital color copying apparatus
or the like, enlargement is an essential function indispensable thereto.
Accordingly, an image reading arrangement for transmitting binary-coded
data of an image to a digital copying apparatus, etc., is required to be
provided with an enlarging or magnifying function.
The enlarging or magnifying system for the image reading arrangement may be
broadly divided into an optical magnifying type and an electrical
magnifying type. In the optical magnifying type, the optical system is
provided with a zoom function so as to read the image through enlarging of
an image of the original document incident upon an image pickup element,
while in the electrical magnifying type, the data read at a fixed
magnification (fixed resolution) is processed.
In the variation of magnification through electrical processing, it is
possible in principle to adopt any desired magnification, without
limitations in the upper or lower limit value thereof. In the
magnification variation, particularly in the direction of enlarging,
however, deterioration of images tends to take place, since data which is
not read originally must be prepared in a pseudo practice. On the other
hand, in the variation of magnification by the optical system, it may be
regarded that deterioration of the image quality is almost nil, and
accordingly, upon comparison of the optical magnifying with the electrical
magnifying, the optical magnifying is advantageous in terms of image
quality.
Meanwhile, a disadvantage in the adoption of the optical magnifying is that
there may be formed portions which can not be read on the original
document as described hereinbelow.
FIGS. 11(a) and 11(b) respectively show the relation between an original
document and a CCD (charge coupled device) surface during an equal size or
life size magnification and during enlargement. In the equal size
magnification, the image on the entire surface of the original document
(in a main scanning direction) is projected over the CCD surface as shown
in FIG. 11(a), whereas during the enlarging, the image on the entire
surface of the original document is not projected over the CCD surface as
illustrated in FIG. 11(b). In other words, regions M and M' at opposite
edges on the surface of the original document can not be read.
In the general enlarging operation (e.g., conversion from an A5 size
original document into A4 size), no inconvenience is experienced in many
cases, even if such unreadable portions are present.
However, in the case where the original document is of a maximum size for
equal size reading, with a partial enlarging being required to be
effected, there are cases where the region aimed at enters the unreadable
region M or M'.
In the conventional practice, when the state as described above takes
place, there is no other way than to displace the original document into
the readable region by an operator. For such an editing work, it is
frequently required to designate the enlarged reading region after
monitoring by a monitor device such as a CRT and the like subsequent to
once reading the whole image surface at an equal size magnification, thus
resulting in necessity for the operator to displace the original document
depending on adopted magnifications and regions, or in obstruction against
smooth operation. Particularly, in the case where an automatic document
feeder is employed, it is impossible for the operator to displace the
original document to its position.
SUMMARY OF THE INVENTION
Accordingly, an essential object of the present invention is to provide an
image reading arrangement which is provided with both optical magnifying
and electrical magnifying functions for the improvement of magnifying
power.
Another object of the present invention is to provide an image reading
arrangement of the above described type which is simple in construction
and stable in functioning.
In accomplishing these and other objects, according to one preferred
embodiment of the present invention, there is provided an image reading
arrangement which comprises an optical projecting mechanism for projecting
an image of an original document, an image reading device for converting
the projected image into an electrical image signal, a first magnifying
means associated with said optical projecting mechanism for optically
enlarging the size of the image to be projected onto said image reading
device, a second magnifying means including a memory means for temporarily
storing an electrical image signal and arranged to electrically enlarge
the size of an image by controlling writing and reading of the image
signal into and from said memory means, a magnification input means for
inputting enlarging magnification when the size of the image of the
original document is enlarged, a region input means for inputting data
designating a region on the original document to be read and outputted,
and a control means for controlling said first and second magnifying means
in response to said magnification input means and said region input means,
and said control means effects the control in such a manner that, when an
entire region as designated can not be read if only said first magnifying
means is operated at the input magnification, said control means sets
magnification to be used in each of said first and second magnifying means
so as to cause said first and second magnifying means to function
simultaneously.
In the above arrangement of the present invention, the image reading
arrangement provided with an optical magnifying means and an electrical
magnifying means is so arranged that, in the case where the reading
designated range can not be read by the designated magnification, even if
the magnification is that which can be covered by the optical magnifying,
the electrical magnifying means is also utilized. More specifically, in
one aspect of the present invention, the optical magnifying is effected up
to the limit at which the designated magnification can be read, and the
remaining enlargement is electrically effected. In another aspect, if the
designated region can not be optically read at the designated
magnification, the optical magnifying is set at the equal size
magnification, and the electrical enlarging is employed.
In both of the above two practices, if the designated region is within a
range which can be covered by the optical enlargement, the optical
magnifying is to be preferentially used.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and features of the present invention will become
clear from the following description taken in conjunction with the
preferred embodiments thereof with reference to the accompanying drawings,
in which:
FIG. 1 is a flow-chart for explaining a variable magnification processing
in an image reading arrangement according to one preferred embodiment of
the present invention;
FIG. 2 is a flow-chart showing another embodiment of the variable
magnification processing;
FIG. 3 is a side sectional view of an original document reading arrangement
according to one preferred embodiment of the present invention;
FIG. 4 is a fragmentary top plan view of a lens displacing system employed
in the arrangement of FIG. 3;
FIG. 5 is a schematic block diagram showing general internal construction
of the original document reading arrangement;
FIG. 6 is a block diagram showing an electrical magnification varying
section for the arrangement of FIG. 5;
FIG. 7 is a timing-chart for clocks in the electrical magnification varying
section;
FIGS. 8(a) to 8(d) are diagrams showing reading ranges during two times
enlargement;
FIG. 9 is a flow-chart for explaining the magnifying reading;
FIG. 10 is a flow-chart for the lens displacement; and
FIGS. 11(a) and 11(b) are diagrams respectively showing relation between
the surface of an original document and that of an image pickup element
(CCD) (already referred to).
DETAILED DESCRIPTION OF THE INVENTION
Before the description of the present invention proceeds, it is to be noted
that like parts are designated by like reference numerals throughout the
accompanying drawings.
Referring now to the drawings, one preferred embodiment of the present
invention will be described hereinafter in the order as follows.
(1) Image reader
(2) Internal electrical construction of the image reader
(3) Main flow for variable magnification reading
(4) Variable magnification processing
(1) Image reader
In FIG. 3, there is shown an image reading arrangement or image reader
according to one preferred embodiment of the present invention, which
generally includes a housing H, an original document platform 4 of a light
transmitting material such as glass or the like disposed at an upper
portion of the housing H for placing an original document 6 thereon and
having an original document scale or reference pattern 8 disposed along
its one side edge, a halogen lamp 2 provided below and adjacent to the
platform 4 for illuminating the original document 6, and an optical system
including first, second and third mirrors 12, 14 and 16 for sequentially
leading light reflected by the original document 6, through a lens
assembly 18, to a one-dimensional CCD (charge coupled device) 20 as an
image pickup device, which is supported by a CCD adjusting mechanism or
CCD holder 22 for adjustment of its position and angle, with said CCD
holder 22 and the lens assembly 18 being mounted on a movable table 24.
As shown in FIG. 4, adjustment of magnification is arranged to be effected
by a magnification adjusting motor M2 coupled with a wire pulley 26 wound
with a wire for displacing the moving table 24 back and forth in a
direction of an optical axis along a zoom slide shaft 28, whereby a zoom
magnification variation may be effected.
Focusing adjustment for adjusting deviation in the conjugate length due to
the lens displacement may be effected by displacing the CCD 20 back and
forth in the optical axis direction by a focusing adjusting motor M3
mounted on the movable table 24 through a focusing adjusting mechanism 30.
For the scanning of the original document 6, two sliders on which the light
source 2 and the first, second and third mirrors 12, 14 and 16 are fixed,
are displaced in the scanning direction by a motor M1 through a pulley and
wire arrangement in a known manner.
(2) Internal electrical construction of the image reader
FIG. 5 shows a schematic block diagram of a circuit for detecting density
of the original document. The scan motor M1, lens motor M2 and focus
adjusting motor M3, which are pulse motors, are respectively connected
through pulse motor drivers 34, 36 and 38 to a CPU 30, which is coupled
with the exposure lamp 2, the CCD 20 through an A/D converting section 40,
a shading correction section 42, an electrical magnification varying
section 44, a binary/half tone treating section 46, and an output circuit
48, etc.
To the CPU 30 for controlling reading of the original document, various
input and output signals are connected through a communication system not
particularly shown. The input signals include a dot density signal (e.g.
240, 300, 400 dots/inch) for setting resolution of a printer, a
magnification signal for setting magnifications for image reading, a
region signal for designating the region to be partially enlarged as
represented by X-Y coordinates, and a start signal for starting reading
function, etc., which are inputted through a control panel (not shown).
There are also included such signals as a lens position signal which is
outputted when the lens assembly 18 is at the initial position, a slider
predetermined position signal which is outputted when the slider is at the
predetermined position, and an original document leading edge signal which
informs that the slider is at the leading edge of the original document.
The scan motor M1, lens motor M2 and focus adjusting motor M3 are driven by
the CPU 30 via the pulse motor drivers 34, 36 and 38 respectively.
An exposure lamp signal is also applied to illuminate the exposure lamp 2.
Light irradiated by the exposure lamp 2 and reflected from the original
document is incident upon the CCD 20 through the optical system. The
output signal of the CCD 20 is converted into a digital value of multiple
bit form by the A/D converting section 40, and after being corrected for
shading at the shading correction section 42, electrically varied in the
magnification at the electrical magnification varying section 44.
Thereafter, the signal is converted into a digital one bit signal from
multiple bit form by the binary/half tone treating section 46, and is
externally outputted (e.g. to an electrophotographic printer) through the
output circuit 48. Each of the processing sections 40, 42, 44, 46 and 48
are applied with control signals from the CPU 30. Here, the signals such
as those for the scanning function starting, selection of magnification to
be varied, selection of the binary/half tone processings, etc. are applied
to the CPU 30 through the communication system (not shown).
FIG. 6 shows a block diagram for one example of the electrical
magnification varying section 44 for electrically varying magnification of
the image as referred to above.
The electrical magnification varying section 44 generally includes a first
address generating counter or writing address generating counter 60 and a
second address generating counter or reading address generating counter 74
which are connected with a thinning-out clock generating 73 and further
coupled with a first line RAM 62 and a second line RAM 72 through
selectors (S1, S3) 64 and 68, while said first and second line RAMs 62 and
72 are coupled with the processing section at the previous stage, and also
with the processing section at the subsequent stage through selectors (S2,
S4) 66 and 70 respectively as shown.
The image signal from the shading correction section 42 is written in the
first line RAM 62 through the selector (S2) 66 for one line by an address
Adrs W produced by the writing address generating counter 60 through a
clock CKA. Subsequently, the selectors (S1 to S4) 64, 66, 68 and 70 are
simultaneously changed over, and the signal with respect to the next one
line is written in the second line RAM 72. In such a manner, the image
signal for one line is alternately written in the pair of line RAMs 62 and
72.
For reading out, the thinning-out clock generating section 73 generates a
clock CKB in which the clock CKA is thinned out, in correspondence to a
thinning-out rate signal from the CPU 30 and the clock CKA. The reading
address generating counter 74 generates an address Adrs R for reading the
line RAMs 62 and 72 by an address generation initial value sent from the
CPU 30 and the clock CKB. It is to be noted here that both reading and
writing of data from and into the memory are effected at the timing of the
clock CKA.
When the line RAMs 62 and 72 are read by the above address Adrs R, if they
are read at the timing of the clock CKA, the same address Adrs R as before
is to be read with respect to the thinned-out portion of the clock CKB. By
way of example, as shown in FIG. 7, if the thinning-out is effected for
every other pulse, each one address is to be read twice, and thus, the
image signal magnified by two times is obtained.
Of course, upon magnification by two times, the range which can be read in
the line RAMs 62 and 72 will become 1/2 with respect to the region written
in. Therefore, the address generating initial value is set from the CPU
30. For example, if the total addresses are of N pieces as shown in FIG.
8(a), when the address generating initial values are represented by .phi.,
N/4, and N/2 at the magnification by two times, hatched portions in FIGS.
8(b), 8(c) and 8(d) are respectively outputted as the image data of N
pieces.
FIGS. 8(b), 8(c) and 8(d) respectively show cases where the left side half
portion, central portion, and right side half portions of the image are to
be partially enlarged.
(3) Main flow for variable magnification reading
Referring further to a flow-chart of FIG. 9, the flow for magnification
reading according to the present invention will be explained hereinafter.
Upon turning on the power source, the initial setting is first effected
(step P1). Subsequently, the lens assembly is returned to an initial
position (life size or equal size magnification position) by the lens
motor M2 (step P2), and the slider is also returned to the predetermined
fixed position by the scan motor M1 (step P3).
In the first place, it is checked whether or not the dot density is altered
(step P5). If there is any alteration, magnification varying processing is
effected (step P6) and the procedure reverts to step P5. Subsequently, it
is judged whether or not the magnification is varied (step P7). If there
is any variation, the magnification varying processing is effected (step
P6), and the procedure is returned to step P5. Although the magnification
varying processing will be described in detail in item (4) later,
according to the present embodiment, the optical magnification variation
is adopted within the range capable of optically varying the
magnification, and if the state is outside such range, the optical
magnification variation is combined with the electrical magnification
variation both for alterations of dot density and magnification.
Thereafter, it is judged whether or not the start signal is inputted (step
P8). If it is not inputted, the procedure returns to step P5. As soon as
there is an input, scanning for the original document reading is effected
at a speed corresponding to the actual magnification (step P9). Upon
completion of the scanning, the procedure returns to step P5.
(4) Variable magnification processing
In the case of image enlarging, both the optical magnifying and electrical
magnifying are simultaneously used. Although the optical magnifying is
superior to the electrical magnifying in that the image quality is not
deteriorated, when such optical magnifying is utilized, there may be a
case where a region which can not be read occurs on the original document
platform, and the electrical magnifying is utilized to read such
unreadable region.
The magnifying method as referred to above may be classified into the
following two kinds.
(i) If the designated region can not be optically read at the designated
magnification, the optical magnifying is used as far as the designated
region is covered thereby, and the insufficient portion of the
magnification is supplemented by the electrical magnifying.
(ii) In the case where the designated region can not be optically read at
the designated magnification, the optical magnifying is set at an equal
size magnification, and the electrical enlarging is employed.
In any of the above two practices, if the designated region is within a
range which can be covered by the optical enlargement, the optical
magnifying is to be preferentially used.
FIG. 1 shows a flow of the variable magnification processing (a) with
respect to the magnifying method (i) referred to above.
In the first place, it is checked whether or not the designated
magnification E0 is within the range in which the optical magnifying can
be effected (step P50). If the result is NO, another treatment such as the
combination with the electrical magnifying, etc. is to be effected.
Meanwhile, if the designated magnification is within the range capable of
effecting the optical magnifying, the maximum magnification E1 capable of
reading the entire designated region is calculated (step P51).
If the relation is E0.ltoreq.E1 (step P52), the lens assembly 18 is moved
up to the position of the designated magnification E0 (step P53).
In the case where the relation is E0>E1 (step P52), the lens assembly 18 is
moved up to the position of the magnification E1 at the upper limit
capable of covering the designated region (step P54) for effecting the
optical magnification. Then, E0/E1 is calculated as the magnification E2
for the electrical magnifying (step P55), and the magnification E2 is set
at the electrical magnification varying section 22 (step P56), with an
initial address being set to read the designated region (step P57).
FIG. 2 shows a flow for the variable magnification processing (b) with
respect to the magnifying method (ii) referred to above.
In the first place, it is checked whether or not the designated
magnification is within the range in which the optical magnifying can be
effected (step P60). If the result is NO, another treatment such as the
combination of the optical magnifying (the upper limit magnification) with
the electrical magnifying, etc. is to be effected. Meanwhile, if the
designated magnification is within the range capable of effecting the
optical magnifying, it is subsequently judged whether or not the
designated region can be read during the optical magnifying (step P61). If
the result is YES, the lens assembly 18 is displaced up to the position
corresponding to the designated magnification (step P62).
If it is impossible to read the designated region during the optical
magnifying, the lens assembly 18 is displaced to the equal size
magnification position (step P63). Then, the designated magnification
(thinning-out ratio signal) is applied to the electrical magnification
varying section 44 (step P64), and the address generation initial value
for reading the designated region is set (step P65).
Subsequently, the lens displacement (steps P53, P54, P62 and P63) will be
described in detail with reference to the flow-chart of FIG. 10.
In the first place, actual magnification within the reading device is
calculated by the inputted magnification and dot density of the printer
(step P21). Here, 240 dots/inch are set as the fundamental magnification.
Accordingly, the equal size magnification at 240 dots/inch is the actual
size magnification at one time, and the equal size magnification at 480
dots/inch becomes the actual size magnification at two times. Then, the
position of the lens assembly 18 corresponding to the actual magnification
is calculated (step P22). Subsequently, the difference between the present
lens position and the new lens position obtained at step P22 is set to be
the distance of displacement of the lens assembly 18, with the
displacement corresponding to alteration by one phase of the lens motor
being set as a unit (step P24). Thereafter, it is checked whether the
displaced distance is positive or negative (step P26). If said distance is
positive, the direction of displacement is represented by CW which is the
displacing direction in the case of "positive" (step P27). Meanwhile, if
the displaced distance is negative, the symbol for said distance is made
positive (step P28), and the moving direction is represented by CCW which
is in the opposite direction to CW (step P29).
Then, present phase is applied to the lens motor M2 (step P30). After
waiting for a predetermined period of time (step P32), the phase is
renewed (step P34). 1 is subtracted from the displaced distance (step
P36), and it is checked whether or not the displaced distance has become 0
(step P37). If the result is "NO", the procedure returns to step P30 for
further displacement. Upon completion of displacement by a predetermined
distance, the lens motor M2 is stopped (step P38). Then, the CCD 20 is
moved for the focus adjustment by the focus adjusting motor M3 so that the
difference of detected density for the white/black pattern of the
reference pattern 8 provided on the transparent original document platform
becomes the maximum (step P39).
As is clear from the foregoing description, according to the arrangement of
the present invention, even the region incapable of reading by the optical
magnifying may be read through employment of the electrical magnifying.
Thus, since it is not necessary for the operator to pay attention to the
setting of an original document, operability is remarkably improved.
Owing to the fact that the optical magnifying is effectively utilized up to
the limit which can cover the designated region, deterioration of images
may be suppressed to the minimum.
Although the present invention has been fully described in connection with
the preferred embodiments thereof with reference to the accompanying
drawings, it is to be noted that various changes and modifications are
apparent to those skilled in the art. Such changes and modifications are
to be understood as included within the scope of the present invention as
defined by the appended claims unless they depart therefrom.
* * * * *
|
|
 |
|
 |
Description |
|
