U.S. patent application number 08/999131 was filed with the patent office on 2001-11-15 for image scanning apparatus.
Invention is credited to FUNAKOSHI, MASAHIRO, SUGA, DAISUKE.
Application Number | 20010040707 08/999131 |
Document ID | / |
Family ID | 26472014 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040707 |
Kind Code |
A1 |
FUNAKOSHI, MASAHIRO ; et
al. |
November 15, 2001 |
IMAGE SCANNING APPARATUS
Abstract
The present invention provides an image reading apparatus
comprising a transparent plate, a convey means for conveying an
original onto the transparent plate, a light source for
illuminating the original, a light receiving element for reading an
image of the original illuminated by the light source through the
transparent plate, the light receiving element being shifted in a
first mode in which the original stopped on the transparent plate
is read and being kept stationary in a second mode in which the
original being shifted by the convey means is read, and a control
means for controlling a light amount of the light source in
accordance with the first mode or the second mode.
Inventors: |
FUNAKOSHI, MASAHIRO;
(TORIDE-SHI, JP) ; SUGA, DAISUKE; (TORIDE-SHI,
JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
26472014 |
Appl. No.: |
08/999131 |
Filed: |
December 29, 1997 |
Current U.S.
Class: |
358/475 |
Current CPC
Class: |
H04N 1/00822 20130101;
H04N 1/0464 20130101; H04N 1/12 20130101; H04N 1/1017 20130101;
H04N 1/193 20130101; H04N 1/40056 20130101; H04N 1/407
20130101 |
Class at
Publication: |
358/475 |
International
Class: |
H04N 001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 1996 |
JP |
8-356946 |
May 15, 1997 |
JP |
9-139106 |
Claims
What is claimed is:
1. An image reading apparatus comprising: a transparent plate; a
convey means for conveying an original onto said transparent plate;
a light source for illuminating the original; a light receiving
element for reading an image of the original illuminated by said
light source through said transparent plate, said light receiving
element is shifting in a first mode in which the original stopped
on said transparent plate is read, and being kept stationary in a
second mode in which the original is being shifted by said convey
means is read; and a control means for controlling a light amount
of said light source in accordance with said first mode or said
second mode of said light receiving.
2. An image reading apparatus according to claim 1, wherein said
control means controls so that the light amount of said light
source when the original is read in said second mode becomes larger
than the light amount of said light source when the original is
read in said first mode.
3. An image reading apparatus comprising: a transparent plate; a
convey means for conveying an original onto said transparent plate;
a light source for illuminating the original; a light receiving
element for reading an image of the original illuminated by said
light source through said transparent plate, said light receiving
element is shifting in a first mode in which the original stopped
on said transparent plate is read, and being kept stationary in a
second mode in which the original is being shifted by said convey
means is read; and a conversion means for determining image density
in accordance with an output from said light receiving element,
said conversion means including a first conversion table for said
first mode and a second conversion table for said second mode.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image reading apparatus
for reading image information on an object to be read by a scanning
operation, and more particularly, it relates to an image reading
apparatus having different scanning systems in which, when the
object to be read is a book having a substantial thickness, the
object is read while shifting an image reading unit, and, when the
object to be read is a thin sheet, the object is read while
shifting the object and which is applicable to a facsimile system
or a copying machine.
[0003] 2. Related Background Art
[0004] Among conventional reading apparatuses in which an image
sensor of close contact type consisting of combination of a light
emitting element array and a light receiving element array is used
as an image reading device, there is an image reading apparatus
having a function for reading two-dimensional image information
from a thick object to be read such as a book and a function for
reading two-dimensional information continuously from a plurality
of fixed-shape sheets to be read.
[0005] Briefly explaining, when a thick original such as a book is
read (first mode), the original is rested on a transparent plate
and an image on the original is read while shifting a reading
device.
[0006] On the other hand, when a sheet-shaped original is read
(second mode), the original is rested on a tray, and an image on
the original is read while automatically conveying the original
onto a transparent plate by means of convey rollers. In this case,
the reading device is stopped at a predetermined position in order
to read the image on the shifting original.
[0007] However, in the second mode, since the sheet-shaped original
conveyed while applying a slight tension force to the original
along a conveying direction to prevent the slack of the
sheet-shaped original at a reading position, the reading is
effected in a condition that the sheet-shaped original is not
completely contacted with the glass plate. To the contrary, in the
first mode, the original is closely contacted with the glass
plate.
[0008] Accordingly, when a light emitting amount of the light
emitting element is constant, illuminance on the original differs
between the first mode and the second mode. If the illuminance
differs, reading density will be varied even regarding the original
having the same image density.
[0009] In a facsimile having an automatic original (document)
feeder (ADF) and an original support plate, when the original is
read from ADF, for example, as shown in FIG. 10, while the original
is being read, diffused reflection light and/or stray light (shown
by the arrows) from a light source 201 is incident on a light
receiving element 203. On the other hand, when the original is read
from the original support plate, for example, as shown in FIG. 11,
since the original 206 is urged against the original support plate
501 by a pressure plate 502, the diffused reflection light and/or
stray light is not incident on the light receiving element 203.
Incidentally, in FIG. 11, the reference numeral 301 denotes an
image sensor.
[0010] In the conventional facsimiles, when image data is
accumulated in a memory, output is emitted with low resolving
power; whereas, when the image data is not accumulated in the
memory, output is emitted with high resolving power. However, in
any cases where the image data is outputted with low resolving
power and where the image data is outputted with high resolving
power, the same luminance/density conversion table is used.
[0011] However, in the above-mentioned conventional techniques,
when the original conveyed from the ADF is read, since the diffused
reflection light and/or stray light is incident on the image
sensor, a reading illuminance value becomes greater in comparison
with a reading illuminance value when the original is read from the
original support plate. Thus, there is a disadvantage that density
of an output image is reduced.
[0012] Further, in the above-mentioned conventional techniques,
when the output resolving power is changed, a recording dot width
is also changed. Thus, since gradient of a recording apparatus is
varied with the output resolving power, even when the same density
value is outputted during the recording, density of images is
varied.
SUMMARY OF THE INVENTION
[0013] The present invention aims to eliminate the above-mentioned
conventional drawbacks, and an object of the present invention is
to provide an image reading apparatus in which the reading can be
effected with high accuracy.
[0014] Another object of the present invention is to provide an
image reading apparatus in which difference in reading density
between a first mode and a second mode is small.
[0015] A further object of the present invention is to provide an
image reading apparatus comprising a transparent plate, a convey
means for conveying an original onto the transparent plate, a light
source for illuminating the original, a light receiving element for
reading an image of the original illuminated by the light source
through the transparent plate, the light receiving element is
shifting in a first mode in which the original stopped on the
transparent plate is read and being kept stationary in a second
mode in which the original is being shifted by the convey means is
read, and a control means for controlling a light amount of the
light source in accordance with the first mode or the second mode
of said light receiving.
[0016] A still further object of the present invention is to
provide an image reading apparatus comprising a transparent plate,
a convey means for conveying an original onto the transparent
plate, a light source for illuminating the original, a light
receiving element for reading an image of the original illuminated
by the light source through the transparent plate, the light
receiving element is being shifted in a first mode in which the
original stopped on the transparent plate is read and being kept
stationary in a second mode in which the original being shifted by
the convey means is read, and a conversion means for determining
image density in accordance with an output from the light receiving
element, which conversion means includes a first conversion table
for the first mode and a second conversion table for the second
mode.
[0017] The other objects of the present invention will be apparent
from the following detailed explanation of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a perspective view of a facsimile apparatus
according to a first embodiment of the present invention;
[0019] FIG. 2 is a perspective view showing the facsimile apparatus
according to the first embodiment, with a discharge tray is
omitted;
[0020] FIG. 3 is a perspective view of the facsimile apparatus
according to the first embodiment in a condition that a pressure
plate is opened;
[0021] FIG. 4 is an elevational sectional view of the facsimile
apparatus according to the first embodiment;
[0022] FIG. 5 is a block diagram of the facsimile apparatus
according to the first embodiment;
[0023] FIG. 6 is a sectional view of an image reading apparatus of
the facsimile apparatus according to the first embodiment, along a
sub scanning direction;
[0024] FIG. 7 is a sectional view of the image reading apparatus of
the facsimile apparatus according to the first embodiment, along a
main scanning direction;
[0025] FIG. 8 is a flow chart showing a reading operation of the
image reading apparatus of the facsimile apparatus according to the
first embodiment;
[0026] FIG. 9 is an electric block diagram of a reading apparatus
according to second and third embodiments of the present
invention;
[0027] FIG. 10 is a sectional view showing an internal structure of
the reading apparatus according to the second and third
embodiments;
[0028] FIG. 11 is a sectional view showing an internal structure of
a main part of the reading apparatus according to the second and
third embodiments;
[0029] FIG. 12 is a perspective view of the reading apparatus
according to the second and third embodiments;
[0030] FIG. 13 is a perspective view of the reading apparatus
according to the second and third embodiments in a condition that a
pressure plate is opened;
[0031] FIG. 14 is a graph showing a relation between normal
illuminance and density; and
[0032] FIG. 15 is an explanatory view showing contents of an
illuminance/density conversion table in the reading apparatus
according to the second embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0033] The present invention will now be explained in connection
with embodiments thereof with reference to the accompanying
drawings. However, dimensions, materials, configurations and
relative positional relations of constructural elements shown in
the embodiments do not limit the present invention, so long as they
are not specified.
[0034] FIGS. 1 to 3 are perspective view of a facsimile apparatus
according to a first embodiment of the present invention, and FIG.
4 is a sectional view of the facsimile apparatus. FIG. 5 is a block
diagram of the facsimile apparatus, FIG. 6 is a sectional view of
an image reading portion of the facsimile apparatus, along a sub
scanning direction, FIG. 7 is a sectional view of the image reading
portion of the facsimile apparatus, along a main scanning
direction, and FIG. 8 is a flow chart showing a reading operation
of the facsimile apparatus.
[0035] [Brief Explanation of Entire Facsimile Apparatus]
[0036] In FIGS. 1, 2, 3 and 4, a flat head scanner 130 serves to
read an image of an original (object to be read) B rested on an
original support glass plate 130a. A pressure plate 102 can be
opened and closed around fulcrums a, b. After the pressure plate
102 is opened, an original D is rested on the original support
glass plate 130a, and the original D can be closely contacted with
the original support glass plate 130a by closing the pressure
plate. An image sensor 108 of close contact type serves as an image
reading unit for reading the image.
[0037] An original stacking part 102b on which a plurality of
originals S can be stacked is provided on an upper surface of the
pressure plate 102. An original separation/convey part 106 is
provided within the pressure plate 102 and serves to separate the
originals S rested on the original stacking part 102b one by one
and convey the separated original so that the image of the original
can be read at a sheet reading part 107 while conveying the
original. The original discharged from the facsimile apparatus is
collected on an original discharge tray 109.
[0038] The reference numeral 104 denotes a laser beam printer
constituting a recording part of electrophotographic type using a
laser beam scanner 110; 111 denotes an image forming part for
transferring an image onto a recording sheet; 112 denotes a
cassette sheet supply part for supplying and conveying sheets one
by one from a box-shaped sheet supply cassette (in which a
plurality of sheets are stacked) toward the image forming part; 125
denotes a manual insertion sheet supply part for separating sheets
(stacked on a recording sheet stacking tray) one by one toward the
image forming part; 116 denotes a fixing part for fixing the image
transferred to the recording sheet in the image forming part 111
onto the recording sheet; 117 denotes a pair of discharge rollers;
and 113 denotes a recording sheet discharge tray on which the
discharged recording sheets are stacked.
[0039] The reference numeral 105 denotes an operation part for
effecting display and input; 120 denotes a control part for
electrically controlling the entire apparatus (such as reading,
communication, operation); and 121 an DC source for supplying DC
electric power to parts of the apparatus.
[0040] In FIG. 5, the reference numeral B100 denotes a system
controller for controlling an electric system of the entire
facsimile apparatus; and B101 denotes a power supply for supplying
electric power to parts of the apparatus. A plug B102 for obtaining
commercial electric power from a plug receptacle is connected to
the power supply B101.
[0041] The reference numeral B110 denotes a reading part for
effecting the reading in the facsimile apparatus. A photoelectrical
conversion element (photoelectric conversion means) B 111
incorporated into the image sensor of close contact type serves to
convert image information of the object to be read into an electric
signal. An analogue image processing part B 112 serves to effect
analogue image treatment of an analogue signal outputted from the
photoelectric conversion element B111, and an A/D converter B113
serves to convert the analogue signal processed in the analogue
image processing part B112 into a digital code. A digital image
processing part B 114 serves to effect digital treatment of the
image information digitalized in the A/D converter B113 and has a
function for correcting an intermediate gradation image to a proper
form. A light emitting element (illumination means) B115 is
incorporated into the image sensor of close contact type together
with the photoelectric conversion element and acts as a light
source for illuminating the object to be read. The light emitting
element B115 is electrically driven by a driver B116. A CS carriage
motor B117 serves to shift the image sensor of close contact type
including the photoelectric conversion element B111 and the light
emitting element B115 in the flat head scanner at the reading part
B110, and an original conveying motor B118 serves to convey a
sheet-shaped object to be read. A motor driver B119 serves to
electrically drive the CS carriage motor B117 and the original
conveying motor B118, and a sensor B120 serves to detect movement
of the parts in the reading part B110.
[0042] In the illustrated embodiment, a recording part B130 for
effecting the recording in the facsimile apparatus is constituted
by an electrophotogrfaphic laser beam printer for forming an image
on a recording sheet by using a laser beam. An operating part B140
for effecting various operations includes LCD B142 as a display
means, an LCD driver B143 for electrically driving the LCD B142 and
a key switch B141 for input means. A communication part B150 for
effecting communication of image information with respect to
another facsimile apparatus and includes a MODEM B151 for
modulating frequency of signals generated in the apparatus into a
signal having frequency band usable in a public telephone lines and
demodulating a signal sent from another facsimile apparatus and an
NCU B152 for controlling connection between the facsimile apparatus
and a subscriber's telephone line B153.
[0043] [Explanation of Image Sensor of Close Contact Type as Image
Reading Unit Constituting Image Reading Apparatus]
[0044] Now, the image sensor 108 of close contact type as the image
reading unit will be explained with reference to FIG. 6. The image
sensor 108 of close contact type (also referred to as "CS" (contact
sensor)) includes an LED array (illumination means) 108a for
illuminating a read surface of the original, a SELFOC (registered
trade mark: Nippon Sheet Glass Co., Ltd.) lens array 108b for
focusing light reflected from the read surface of the original onto
the sensor, and a light receiving element 108c disposed immediately
below the lenses and adapted to effect photoelectric conversion of
the focused reflection light, which elements 108a to 108c are
arranged in a line along a main scanning direction within a frame,
so that one-line of the image of the original can be read without
relative movement between the original and the sensor. The
direction along which the image can be read without the relative
movement between the original and the sensor is referred to as a
main scanning direction which corresponds to a direction
perpendicular to the plane of FIG. 6. In order to read the image of
the original two-dimensionally, the image sensor 108 of close
contact type and the original are shifted relative to each other in
a sub scanning direction parallel to the surface of the original
and perpendicular to the main scanning direction while effecting
the reading in the main scanning direction.
[0045] The SELFOC lens 108b of the image sensor 108 of close
contact type used in the flat head scanner 130 of the facsimile
apparatus according to the illustrated embodiment is of long focus
type and is designed to be focused on an original resting surface
of the original support glass plate 130a having a thickness of 3
mm.
[0046] [Case Where Image is Read by Scanning Effected by Shifting
Image Reading Unit]
[0047] The flat head scanner 130 used when the image is read by
scanning effected by shifting the image reading unit (first mode)
will be explained with reference to FIGS. 3, 4, 6 and 7. The flat
head scanner 130 serves to read a thick original such as a book
while keeping the original stationary and includes the original
support glass plate 130a on which the original B is rested. The
original support glass plate 130a has a thickness of 3 mm and
including an original resting area and a sheet reading area of the
sheet reading portion 107.
[0048] An index plate 130f for indicating positions for resting
various originals B on the original support glass plate 130a is
provided on the original resting surface between the original
resting area and the sheet reading area of the original support
glass plate 130a. The index plate 130f has thickness of 0.5 mm and
has a white surface (providing white level as a reference before
the image is read) contacted with the original support glass plate
130a. A frame 130b of the flat head scanner 130 is a structure for
supporting the original support glass plate 130a. A guide shaft
130c for guiding the shifting movement of the image sensor 108 of
close contact type within the frame 130b is attached to the frame
130b. A CS carriage 130d for shifting the image sensor 108 of close
contact type along the guide shaft 130c is attached to the guide
shaft 130c via bearings 130e in such a manner that the image sensor
108 of close contact type is biased toward the original support
glass plate 130a.
[0049] An original hold-down plate 102e of three-layer structure
comprised of a white plastic film to be contacted with the original
B and a metallic base plate with the interposition of a sponge
layer having a thickness of about 5 mm is supported by the pressure
plate 102 for movement in an up-and-down direction so that, when
the pressure plate 102 is closed, the original hold-down plate 102e
urges the original B on the original support glass plate 130a
against the original support glass plate 130a.
[0050] Rotation fulcrums (referred to as "hinges" hereinafter)
102f, 102g are provided between the pressure plate 102 and the
frame 130b so that the pressure plate 102 can be opened by a
predetermined angle with respect to the frame 130b. After the
pressure plate 102 is opened, the operator can rest the original on
the original support glass plate 130a or remove the original from
the original support glass plate 130a.
[0051] The image sensor 108 of close contact type is shifted along
the guide shaft 130c by a drive means (not shown) in the sub
scanning direction shown by the arrow A perpendicular to the main
scanning direction to read the surface of the original B
two-dimensionally. The image sensor 108 of close contact type is
biased to a surface opposite to the original resting surface of the
original support glass plate 130a so that a distance between the
image sensor 108 of close contact type and the original support
glass plate 130a is always kept constant when the image sensor 108
of close contact type is shifted by the drive means in the sub
scanning direction. With this arrangement, a level of the focus
position of the image sensor 108 of close contact type on the
original support glass plate 130a is kept constant, thereby
obtaining a good image without out-of-focus.
[0052] [Case Where Image is Read by Scanning Effected by Shifting
Object to be Read]
[0053] The original separation/convey part 106 and the sheet
reading part 107 used when the image is read by scanning effected
by shifting the object to be read (second mode) will be explained
with reference to FIGS. 4, 6 and 7. In the original
separation/convey part 106, the originals S rested on the original
stacking plate 102b are firstly sent, by auxiliary convey roller
102d and an auxiliary convey urging plate 102c, to a nip between a
separation roller 106b and a separation piece 106a, where the
originals are separated one by one. The separated original S is
conveyed to the sheet reading part 107 by a feed roller 106e and a
feed sub-roller 106f urged against the feed roller 106e. An
original end detection sensor 107b is disposed in front of the
sheet reading part 107 so that, by detecting tip and trail ends of
the original by the detection sensor, a reading start timing and a
reading finish timing are set in accordance with a length of the
original S.
[0054] An original hold-down roller 107a serves to aid the
conveyance of the original S effected while contacting with the
original support glass plate 130a in the sheet reading part 107 and
receives a rotational driving force from a drive system (not
shown). The original hold-down roller 107a is rotatably supported
by bearings 107c, 107d disposed on both sides of the roller. The
bearings 107c, 107d are contacted with the original support glass
plate 130a, and a distance I between a rotation center of each
bearing and the surface of the original support glass plate 130a is
selected to become greater than a radius r of the original
hold-down roller 107a. Thus, in the condition that the bearings
107c, 107d are contacted with the original support glass plate
130a, the original hold-down roller 107a is not contacted with the
original support glass plate 130a. In the illustrated embodiment, a
gap .delta. (=I-r) between an outer peripheral surface of the
original hold-down roller 107a and the original support glass plate
130a is selected to 0.2 mm.
[0055] The original passed through the sheet reading part 107 is
discharged onto the original discharge tray 109 by original
discharge rollers 106g, 106h.
[0056] When the original S is read, the image sensor 108 of close
contact type is previously positioned below the original hold-down
roller 107a, and, in a condition that the image sensor 108 of close
contact type is kept stationary with respect to the flat head
scanner 130, the image of the original S is read while conveying
the original. To this end, an original conveying speed V.sub.1
provided by the feed roller 106e and the feed sub-roller 106f is
synchronous with a reading speed of the image sensor 108 of close
contact type.
[0057] In this case, by selecting an original conveying speed
V.sub.0 provided by the original discharge rollers 106g, 106h to
become slightly larger than the original conveying speed V.sub.1, a
weal tension force is applied between the feed roller 106e and the
original discharge roller 106g, thereby preventing the slack of the
original S in the sheet reading part 107. Further, the original
hold-down roller 107a protruded toward the original convey path
from a tangential line connecting between a periphery of the feed
roller 106e and a periphery of the original discharge roller 106g
has an urging force sufficient to prevent the bearing of the
original hold-down roller 107a from floating from the original
support glass plate 130a by a pulling force acting on the original
S.
[0058] Thus, when a thickness t of the original S is smaller than
the gap .delta. between the outer peripheral surface of the
original hold-down roller 107a and the original support glass plate
130a, since the gap .delta. is constant and the original S is
conveyed while contacting with the rotating original hold-down
roller 107a, the reading is effected in a condition that the read
surface of the original is spaced apart from the original resting
surface of the original support glass plate 130a by a distance of
(.delta.-t).
[0059] Since the original separation/convey part 106 is provided
within the pressure plate 102, when the pressure plate 102 is
opened with respect to the flat head scanner 130, the original
separation/convey part 106 is also opened together with the
pressure plate 102, with the result that the original convey path
can easily be opened for sheet jam treatment.
[0060] Sliders 102a are provided on the original stacking portion
102b on both lateral sides of the original for sliding movement in
a direction (width-wise direction of the original S) perpendicular
to the conveying direction of the original S, so that lateral edges
of the originals stacked on the original stacking portion 102b can
be aligned with each other. Although not shown, an original
detection sensor (detection means) is provided on the original
stacking portion 102b to electrically determine whether the
original S is set at a position where the original can be conveyed
by the auxiliary convey roller 102d and the auxiliary convey urging
plate 102c.
[0061] [Explanation of Changing (Switching) Operation of Light
Amount of Illumination Means and Image Information Reading
Operation Which are Characteristics of Image Reading Apparatus
According to Illustrated Embodiment]
[0062] Now, an operation for changing (switching) the light amount
of the illumination means and the reading operation will be
explained with reference to FIGS. 6 and 8. Incidentally, in the
illustrated embodiment, the illumination means is constituted by an
LED, and the light amount is changed by changing load voltage
applied to the LED.
[0063] First of all, when the reading operation is started in a
step F00, the image sensor (CS) 108 of close contact type is
shifted to the white reference position corresponding to the rear
surface of the index plate 130f provided on the original support
glass plate 130a in a step F01, and, in a step F02, by turning ON
the LED in the image sensor (CS) 108 of close contact type with
predetermined voltage V.sub.b, the white reference is illuminated.
In a step F03, the white reference level is set on the basis of an
output from the image sensor (CS) 108 of close contact type
corresponding to reflection light from the White-reference.
[0064] Then, in a step F04, the original detection sensor provided
in the original separation/convey part 106 judges whether the
original S is set on the original stacking portion 102b. If it is
judged that the original S is set, the program goes to a step F20,
where the scanning is effected by shifting the object to be read;
whereas, if it is judged that the original S is not set, the
program goes to a step F10, where the scanning is effected by
shifting the image reading unit.
[0065] When it is judged that the original S is set, first of all,
in the step F20, the image sensor (CS) 108 of close contact type is
shifted to the sheet reading position of the sheet reading part
107. Then, when the conveyance of the original S is started in a
step F21, the originals S are separated one by one in the original
separation/convey part 106 and the separated original is conveyed
toward the sheet reading part 107. In a step F22, the LED of the
image sensor (CS) 108 of close contact type is turned ON with
voltage of V.sub.s. In a step F23, the original S conveyed to the
sheet reading position is read by the image sensor (CS) 108 of
close contact type line by line until it is judged that the reading
of the original S is finished in a step F24. Then, in a step F25,
similar to the step F04, the original detection sensor provided in
the original separation/convey part 106 judges whether the original
S exists on the original stacking portion 102b or not. If it is
judged that the original S exists, the program is returned to the
step F21, from where the steps F21 to F24 are repeated by times
corresponding to the remaining number of originals S. In this way,
a plurality of originals Scan be read continuously. In the step
F25, if it is judged that the original does not exist on the
original stacking portion 102b, the program goes to a step F26,
where, after the last original S is discharged, the original
conveying operation is stopped, and the reading operation is
finished in a step F27.
[0066] In the step F04, if it is judged that the original S is not
set, first of all, in the step F10, the image sensor (CS) 108 of
close contact type is shifted to the original (B) reading start
position. In a step F11, the LED of the image sensor (CS) 108 of
close contact type is turned ON with voltage of V.sub.b, and, in a
step F12, the shifting movement of the image sensor (CS) 108 of
close contact type along the guide shaft 130c is started. In a step
F13, the original B is read by the image sensor (CS) 108 of close
contact type line by line until it is judged that the reading of
the original B is finished in a step F14. In the step F14, when it
is judged that the reading of the original B is finished, the
program goes to a step F15, where the shifting movement of the
image sensor (CS) 108 of close contact type is stopped, and the
reading operation is finished in a step F16.
[0067] In this way, when the relative distance between the image
reading unit and the object to be read is changed in accordance
with the scanning systems, by changing the light amount of the
illumination means properly, the luminance of the object to be read
becomes uniform, thereby permitting the recording with optimum
density.
[0068] That is to say, according to the illustrated embodiment, in
the case where the scanning is effected by shifting the object to
be read (first mode), since the relative distance between the image
reading unit and the object to be read is greater than the case
where the scanning is effected by shifting the image reading unit
(second mode), by setting the load voltage applied to the LED in
the first mode to become greater than that in the second mode
(V.sub.s>V.sub.b) to increase the alight amount of the LED, the
luminance of the object to be read can be uniform in both the first
mode and the second mode, thereby permitting the recording with
optimum density.
[0069] [Explanation of Recording Part]
[0070] Now, the recording part 104 will be explained with reference
to FIG. 4. The recording part 4 is disposed at a lower portion of
the facsimile apparatus. In the recording part 104, sheets P from a
sheet supply cassette 112a containing normal fixed-form size sheets
are separated one by one by means of a sheet supply roller 112b,
and then skew-feed of the separated sheet P is corrected by a pair
of regist rollers 124, and then the sheet P is supplied to the
image forming part 111 in synchronous with a control signal from
the control part 120. In the image forming part 111, first of all,
a surface of a photosensitive drum (electrostatic latent image
bearing member) 111a is uniformly charged by a charge member 111b,
and then the surface of the drum is scanned by the laser scanner
110, thereby exposing the drum in response to the image
information. As a result, an electrostatic latent image is formed.
When toner (developer) is adhered to the electrostatic latent image
by means of a developing sleeve (developer bearing member) 111c, a
toner image is formed on the photosensitive drum 111a. By conveying
the sheet P while pinching the sheet between a transfer roller 111f
and the photosensitive drum 111a on which the toner image was
formed, the toner image is transferred onto a surface of the sheet
P contacted with the photosensitive drum 111a. Then, the sheet is
sent to the fixing part 116, where the sheet is conveyed while the
toner image is being fixed to the sheet P by applying heat and
pressure to the sheet by means of a fixing roller 116b and a
pressure roller 116a. The sheet P to which the toner image was
fixed is discharged onto the recording sheet discharge tray 113 by
the pair of discharge rollers 117.
[0071] On the other hand, the sheets P stacked on the manual
insertion sheet supply part 125 are separated one by one by a sheet
supply roller 125a and an opposed separation pad 125b, and
skew-feed of the separated sheet is corrected by the pair of regist
rollers 124. Thereafter, similar to the sheet supplied from the
cassette sheet supply part 112, the toner image is transferred onto
the image forming part 111, and then the toner image is fixed to
the sheet in the fixing part 116, and then the sheet is discharged
onto the recording sheet discharge tray 113.
[0072] Next, a second embodiment of the present invention will be
explained.
[0073] First of all, an appearance of a reading apparatus
(facsimile) according to a second embodiment of the present
invention will be described with reference to FIGS. 12 and 13. In
FIG. 12, the reading apparatus comprises an apparatus body 400
having an operation part 403 including a start button and the like,
and an original stacking unit 404 pivotally mounted on an upper
part of the apparatus body 400. At an upper part of the original
stacking unit 404, there are disposed an automatic original
(document) feeder (ADF) 401 for automatically feeding an original
from an original stack, and an original stack sensor 402 for
detecting the presence of the original stack. Further, in FIG. 5,
an original stacking portion 501 on which the originals are stacked
is provided on the upper surface of the apparatus body 400, and a
pressure plate 502 is provided on a lower surface of the original
stacking unit 404. Since the other mechanisms do not relate to the
second embodiment, explanation thereof will be omitted.
[0074] Next, an internal construction of the reading apparatus
according to the second embodiment will be described with reference
to FIGS. 10 and 11. In FIG. 10, within the apparatus body of the
reading apparatus, there are disposed a light source 201 for
emitting light, a light receiving element 203 for receiving the
light emitted from the light source 201, white reference 204, and
an original reading position 205. The reference numeral 202 denotes
diffused reflection light and stray light; and 206 denotes the
original. Further, in FIG. 11, an image sensor 301 (refer to FIG.
9) is disposed at a side of the light source 201, and the original
stacking portion 501 (on which the originals are stacked) and the
pressure plate 502 are disposed above the light source 201. Since
the other mechanisms do not relate to the second embodiment,
explanation thereof will be omitted.
[0075] FIG. 14 is a graph showing a relation between a luminance
value and a density value. FIG. 15 is an explanatory view showing
contents of an illuminance/density conversion table (refer to FIG.
9) determining a corresponding relation between the luminance value
and the density value in the reading apparatus according to the
second embodiment.
[0076] Now, an electrical arrangement of the reading apparatus
according to the second embodiment will be explained with reference
to FIG. 9. The reading apparatus includes an image sensor 301, a
luminance correcting part 302, a luminance/density converting part
303, a luminance/density converting table (RAM) 304, a ROM 305, a
digitize processing part 306, a transmitting part 307, a record
output part 308, a recording device 309, an image memory 310, and a
pixel density converting part 311.
[0077] The image sensor 301 serves to read a number of divided line
portions of the original from a tip end to a trail end thereof. The
luminance correcting part 302 is of LSI type in which output
voltage of the image sensor 301 is A/D-converted and the luminance
value one line white reference is stored in a memory of the
luminance correcting part 302. The luminance/density converting
part 303 serves to converts the obtained luminance value into a
corresponding density value while referring to the
luminance/density converting table shown in FIG. 15. The
corresponding relation between the luminance value and the density
value is stored in the luminance/density converting table (RAM)
304. A plurality kinds of luminance/density converting tables are
stored in the ROM 305.
[0078] The digitize processing part 306 serves to effect multi
value.fwdarw.digital value treatment regarding the density value
converted by the luminance/density converting part 303. Conversion
from the multi value to digital value will be described later. The
transmitting part 307 serves to transmit a digitalized image data
to external equipment. The record output part 308 serves to supply
the digitalized image data to the recording device 309. The
recording device 309 serves to record the image data. Various image
data are stored in the image memory 310. The pixel density
converting part 311 serves to effect pixel density conversion on
the basis of the density value converted by the luminance/density
converting part 303.
[0079] Next, an operation of the reading apparatus (facsimile)
according to the second embodiment having the above-mentioned
construction will be explained with reference to FIGS. 9 to 15.
[0080] After the originals are stacked on the ADF 401 or on the
original stacking portion 501 of the reading apparatus (facsimile)
and the pressure plate 502 is closed, when the start button of the
operation part 403 is depressed, the reading operation is started.
When the original reading is started, first of all, the light
source 201 is turned ON to effect shading correction (correction of
color unevenness of input image), and light reflected from the
white reference 204 is incident on the light receiving element
203.
[0081] In this case, since minute light receiving elements are
aligned with each other in a line within the light receiving
element 203, a single thin line can be read. When one like
receiving element is regarded as one pixel, voltage corresponding
to intensity of the reflection light is outputted for each
pixel.
[0082] The luminance correcting part 302 A/D-converts the output
voltage, and the luminance value of the one-line white reference is
stored in the memory of the luminance correcting part 302. The
original stack sensor 402 provided on the ADF 401 judges whether
the original should be read from the ADF 401 or from the original
stacking portion 501. When the original is read from the ADF 401,
after the image sensor 301 is shifted to a position where the
reading position 105 can be read by the image sensor, the number of
divided line portions of the original from the tip end to the trail
end thereof are read while conveying the original. On the other
hand, when the original is read from the original stacking portion
501, the number of divided line portions of the original from the
tip end to the trail end thereof are read while shifting the image
sensor 301.
[0083] The luminance value of one-line read by the image sensor 301
is standardized by the luminance value of the white reference 204
at the corresponding pixel position and the number of process
gradations (for example, 64 gradations) is calculated, thereby
determining the luminance of the pixel. Normally, the luminance
value and the density value have a relation shown in FIG. 14, where
the abscissa indicates luminance and the ordinate indicates
density. Regarding the same original, when the original is read
from the ADF 401, the luminance becomes greater in comparison with
the case where the original is read from the original stacking
portion 501. Accordingly, if the luminance/density conversion is
effected on the basis of the identical luminance/density conversion
table, the density values converted will be changed, even regarding
the same original.
[0084] In the treatment according to the second embodiment
described herein below, when the original is read from the ADF 401,
the luminance/density conversion table having the greater density
values (outputted regarding the luminance values) in comparison
with the case where the original is read from the original stacking
portion 501 is written in the RAM 304 from the ROM 305 in which the
plurality of luminance/density conversion tables are stored, so
that substantially the same density can be obtained both when the
original is read from the ADF 401 and when the original is read
from the original stacking portion 501, so long as the same
original is used.
[0085] After the required correction treatment are performed, the
obtained luminance value is converted into the corresponding
density value by the luminance/density converting part 303 while
referring to the luminance/density conversion table for determining
the corresponding relation between the luminance values and the
density values shown in FIG. 15. For example, in case where the
luminance value is 2, when the original is read from the ADF 401,
the density value is converted into 24, and when the original is
read from the original stacking portion 501, the density value is
converted into 22.
[0086] Further, conversion from the multi value to digital value is
effected regarding the density value converted by the
luminance/density converting part 303. In this case, although there
are various conversion method from multi value to digital value, in
an error dispersing method, regarding the density value of a pixel
in question, a middle value of the gradations (for example, if
there are 64 gradations, a value of 31) is used as a threshold
value, and, it is judged as "black" if the density value is greater
than the threshold value and it is judged as "white" if the density
value is smaller than the threshold value. In this case, the
difference in density between the density value of the pixel in
question and the density value (density 63) of black or the density
value (density 0) of black is regarded as an error, and the
digitize processing is effected while distributing the error to
surrounding pixels at a predetermined rate. Thereafter, the digital
(two-value) data obtained by the digitize processing part 306 is
used as the image data in the transmitting part 307 and the record
output part 308.
[0087] As mentioned above, according to the second embodiment,
since the reading apparatus includes the ROM 305 for storing the
plurality of kinds of luminance/density conversion tables for
determining the relation between the luminance values and the
density values, the original stack sensor 402 for determining
whether the original is read from the ADF 401 or from the original
stacking portion 501, and the luminance/density converting part 303
for effecting the luminance/density conversion by using the
luminance/density conversion table having the greater density
values (outputted regarding the luminance values) in comparison
with the case where the original is read from the original stacking
portion 501 when the original is read from the ADF 401, the output
image density during the copying operation can be controlled to be
uniform even when the original is read from the ADF 401 and when
the original is read from the original stacking portion 501.
[0088] [Third Embodiment]
[0089] Similar to the second embodiment, a reading apparatus
according to a third embodiment of the present invention comprises
an apparatus body 400 having an operation part 403 including a
start button, a sheet number button and the like, an original
stacking portion 501, an automatic original (document) feeder (ADF)
401, an original stack sensor 402, and a pressure plate 502 (refer
to FIGS. 12 and 13).
[0090] Further, similar to the second embodiment, within the
apparatus body 400 of the reading apparatus according to a third
embodiment, there are disposed a light source 201, a light
receiving element 203, white reference 204, an original reading
position 205, and an image sensor 301 (refer to FIGS. 10 and
11).
[0091] Further, similar to the second embodiment, the reading
apparatus according to a third embodiment includes the image sensor
301, a luminance correcting part 302, a luminance/density
converting part 303, a luminance/density converting table (RAM)
304, a ROM 305, a digitize processing part 306, a transmitting part
307, a record output part 308, a recording device 309, an image
memory 310, and a pixel density converting part 311 (refer to FIG.
9).
[0092] Next, an operation of the reading apparatus (facsimile)
according to the third embodiment having the above-mentioned
construction will be explained with reference to FIGS. 9 to 13.
[0093] For example, when a single original is read by using the ADF
401 and a plurality of copies are obtained, since the same original
cannot be read by plural times, if the image memory is few, after
the read luminance value is converted by the pixel density
converting part 311 with low resolving power, the luminance value
is converted into the density, and the digitized image data is
stored in the image memory 310 and is outputted to the recording
device 309 which was switched to low resolving power.
[0094] High resolving power output luminance/density converting
tables and low resolving power output luminance/density converting
tables for the reading from the ADF 401 and the reading from the
original stacking portion 501 are stored in the ROM 305.
[0095] When the single original is read by using the ADF 401 and a
plurality of copies are obtained or when the single original is
read by using the ADF 401 and a single copy is obtained, after the
originals are stacked on the ADF 401 of the reading apparatus
(facsimile), by depressing the copy number button and the start
button (in case of plural copies) or by depressing the start button
(in case of single copy), the reading operation is started. When
the original reading is started, first of all, the light source 201
is turned ON to effect shading correction (correction of color
unevenness of input image), and light reflected from the white
reference 204 is incident on the light receiving element 203.
[0096] In this case, since minute light receiving elements are
aligned with each other in a line within the light receiving
element 203, a single thin line can be read. When the light
receiving element is regarded as one pixel, voltage corresponding
to intensity of the reflection light is outputted for each
pixel.
[0097] The luminance correcting part 302 A/D-converts the output
voltage, and the luminance value of the one-line white reference is
stored in the memory of the luminance correcting part 302. When the
original is read from the ADF 401, after the image sensor 301 is
shifted to a position where the reading position 105 can be read by
the image sensor, the number of divided line portions of the
original from the tip end to the trail end thereof are read while
conveying the original. The luminance value of one-line read by the
image sensor 301 is standardized by the luminance value of the
white reference 204 at the corresponding pixel position and the
number of process gradations (for example, 64 gradations) is
calculated, thereby determining the luminance of the pixel.
[0098] As mentioned above, for example, when the single original is
read by using the ADF 401 and the plurality of copies are obtained,
since the same original cannot be read by plural times, if the
image memory is few, by converting the read luminance value with
low resolving power by means of the pixel density converting part
311, consumption of the memory is reduced. On the other hand, as
mentioned above, when the single is read by using the ADF 401 and
the single copy is obtained, since it is not required that the
image data is stored in the image memory 310, the image data with
high resolving power is outputted without effecting the pixel
density conversion. In dependence upon the fact that the image is
outputted with low resolving power or high resolving power, since
the diameter of the output dot is changed, gradient is also
changed. Thus, even when the digital data
multi-value/two-value-converted from the same density value is
outputted, output density is varied.
[0099] In the treatment according to the third embodiment described
herein below, when the data is outputted with low resolving power,
the low resolving power output luminance/density conversion table
is written in the RAM 304 from the ROM 305, so that substantially
the same density can be obtained both when the data is outputted
with low resolving power and when the data is outputted with high
resolving power.
[0100] After the required correction treatment are performed, the
obtained luminance value is converted into the corresponding
density value by the luminance/density converting part 303 while
referring to the luminance/density conversion table written in the
RAM 304. Further, conversion from the multi value to binary value
is effected by the binary processing part 306 regarding the density
value converted by the luminance/density converting part 303.
[0101] When the image data is not stored in the image memory 310,
the digital image data obtained by the digitize processing part 306
is transferred to the record output part 308. Thereafter, the data
is outputted from the record output part 308 to the recording
device 309. Further, the digital image data can be transmitted to
the transmitting part 307. On the other hand, when the image data
is stored in the image memory 310, after the digital image data
obtained in the digitize processing part 306 is stored in the image
memory 310, the digital image data is transferred from the image
memory 310 to the record output part 308 by plural times.
Thereafter, the data is outputted from the record output part 308
to the recording device 309. Further, the digital image data can be
transmitted to the transmitting part 307 by plural times.
[0102] As mentioned above, according to the third embodiment, since
the reading apparatus includes the ROM 305 storing the plurality of
kinds of luminance/density conversion tables for determining the
relation between the luminance values and the density values, the
recording device 309 capable of changing the output resolving power
of the image, and the luminance/density converting part 303 for
effecting the luminance/density conversion in accordance with the
output resolving power when the image is recorded by the recording
device 309, i.e., for effecting the luminance/density conversion by
using the low resolving power output luminance/density conversion
table when the data is outputted with low resolving power and by
using the high resolving power output luminance/density conversion
table when the data is outputted with high resolving power, the
output image density during the copying operation can be controlled
to be uniform even when the data is outputted with low resolving
power and when the data is outputted with high resolving power.
[0103] Incidentally, the present invention may be applied to a
system comprised of a plurality of equipments or to an apparatus
comprised of a single equipment. Of course, it should be noted that
a memory medium storing a program code of software for performing
the operations of the above-mentioned embodiments is supplied to
the system or the apparatus, and a computer (or CPU or MPU) of the
system or the apparatus reads out the program code stored in the
memory medium and carries out the program code.
[0104] In this case, the program code itself read out from the
memory medium achieves the functions of the above-mentioned
embodiments, and the memory medium storing such program code
constitutes a part of the present invention.
[0105] The memory medium storing the program code may be, for
example, a floppy disc, a hard disc, an optical disc, a
photo-magnetic disc, a CD-ROM, a CD-R, a magnetic tape, a
non-volatile memory card or a ROM.
[0106] Further, by performing the program code read out by the
computer, not only the functions of the above-mentioned embodiments
can be achieved, but also a part of entire of the actual treatments
can be carried out by an OS activating on the computer to achieve
the functions of the above-mentioned embodiments.
[0107] Further, after the program code itself read out from the
memory medium is written in a memory of a function extension board
inserted into the computer or a function extension unit connected
to the computer, a part of entire of the actual treatments can be
carried out by a CPU of the function extension board or the
function extension unit to achieve the functions of the
above-mentioned embodiments.
[0108] The present invention is not limited to the above-mentioned
embodiments, but various alterations and modifications can be made
within the scope of the invention.
* * * * *