U.S. patent application number 09/875386 was filed with the patent office on 2001-12-06 for image scanning apparatus.
This patent application is currently assigned to MURATA KIKAI KABUSHIKI KAISHA. Invention is credited to Nose, Yoshitaka, Onaka, Ryuichi.
Application Number | 20010048830 09/875386 |
Document ID | / |
Family ID | 27343634 |
Filed Date | 2001-12-06 |
United States Patent
Application |
20010048830 |
Kind Code |
A1 |
Nose, Yoshitaka ; et
al. |
December 6, 2001 |
Image scanning apparatus
Abstract
An image scanning machine includes a document feeder for feeding
sheets into a first paper path from a stack one sheet at a time if
a one-side scanning mode is selected. If a both-side scanning mode
is selected, a sheet is introduced into a second paper path which
is an inverting path that turns a sheet, which is fed from the
document feeder, upside down prior to scanning. Rollers located at
a downstream end of the inverting path reverse a transportation
direction of the sheet and feed the sheet to a scanner through a
return path. The transportation direction of the sheet is reversed
after the scanner scans one side of the sheet, and the sheet is
then fed to the scanner again to scan the other side of the sheet.
This transportation direction reversal results in turning the sheet
upside down. A guide member is located a bifurcation of the return
path and the inverting path for opening one of the return and
inverting paths and closing the other of the return and inverting
paths. Another guide member is located a bifurcation of the first
and second paper paths.
Inventors: |
Nose, Yoshitaka; (Kyoto-shi,
JP) ; Onaka, Ryuichi; (Kanzaki-gun, JP) |
Correspondence
Address: |
HOGAN & HARTSON L.L.P.
500 S. GRAND AVENUE
SUITE 1900
LOS ANGELES
CA
90071-2611
US
|
Assignee: |
MURATA KIKAI KABUSHIKI
KAISHA
|
Family ID: |
27343634 |
Appl. No.: |
09/875386 |
Filed: |
June 5, 2001 |
Current U.S.
Class: |
399/374 |
Current CPC
Class: |
H04N 1/00657 20130101;
H04N 1/00578 20130101; H04N 1/00822 20130101; H04N 1/0058 20130101;
H04N 1/00591 20130101; Y10S 271/902 20130101; H04N 1/00602
20130101; H04N 1/00628 20130101; H04N 1/00588 20130101; H04N 1/0057
20130101; G03G 15/23 20130101 |
Class at
Publication: |
399/374 |
International
Class: |
G03G 015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 6, 2000 |
JP |
2000-169170 |
Jul 13, 2000 |
JP |
2000-212373 |
Nov 24, 2000 |
JP |
2000-357409 |
Claims
What is claimed is:
1. An image scanning apparatus comprising: a scanner; a document
feeder for receiving sheets in a stack and feeding one sheet at a
time, each sheet having two sides; an inverting path for turning a
sheet, which is fed from the document feeder, upside down before
scanning; a transportation means located at a downstream end of the
inverting path for reversing a transportation direction of the
sheet and feeding the sheet to the scanner so as to scan one side
of the sheet; and a reversing means for reversing the
transportation direction of the sheet after the scanner scans the
one side of the sheet, and feeding the sheet to the scanner again
to scan the other side of the sheet.
2. The image scanning apparatus according to claim 1, wherein the
transportation means includes a return path for guiding the sheet
from the downstream end of the inverting path to the scanner, and a
guide member is located a bifurcation of the return path and the
inverting path for opening one of the return and inverting paths
and closing the other of the return and inverting paths, whereby it
is possible to introduce the sheet into the return path after the
sheet is fed towards the scanner from the downstream end of the
inverting path.
3. The image scanning apparatus according to claim 1 or 2, wherein
the transportation means includes at least one roller, and the
reversing means includes at least one roller.
4. The image scanning apparatus according to claim 2, wherein the
guide member pivots as the transportation means rotates.
5. The image scanning apparatus according to claim 4, wherein the
guide member is operatively connected to the transportation means
via a torque limiter.
6. The image scanning apparatus according to claim 1, wherein three
rollers are arranged to form two pairs of rollers, and one of the
two pairs of rollers constitute the transportation means whereas
the other pair of rollers constitute the reversing means.
7. The image scanning apparatus according to claim 6 further
including discharging means for discharging the sheet from the
image scanning apparatus after the two sides of the sheet are
scanned, wherein the other pair of rollers also constitute the
discharging means.
8. The image scanning apparatus according to claim 7, wherein two
rollers are arranged to constitute all of the transportation means,
reversing means and discharging means.
9. An apparatus for scanning front and back sides of a sheet
comprising: scanning means; document feeding means for feeding
sheets sheet by sheet, each sheet having front and back sides;
means for turning a sheet, which is fed from the document feeding
means, upside down before scanning; means for reversing a
transportation direction of the sheet and feeding the sheet to the
scanning means so as to scan a back side of the sheet; means for
reversing the transportation direction of the sheet after the
scanning means scans the back side of the sheet; means for feeding
the sheet to the scanning means again to scan the back side of the
sheet; and means for discharging the sheet from the apparatus.
10. A method of scanning front and back sides of a sheet comprising
the steps of: A) feeding a sheet into a scanning machine; B)
turning the sheet upside down before scanning; C) reversing a
transportation direction of the sheet and feeding the sheet to a
scanner so as to scan a back side of the sheet; D) reversing the
transportation direction of the sheet after the scanner scans the
back side of the sheet; E) feeding the sheet to the scanner again
to scan the back side of the sheet; and F) discharging the sheet
from the scanning machine.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority under 35 USC 119 of
Japanese Patent Application Nos. 2000-169170, 2000-357409 and
2000-212373 filed in JPO on Jun. 6, 2000, Nov. 24, 2000 and Jul.
13, 2000 respectively, the entire disclosures of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an image scanning apparatus
that can read both front and back sides of each of sheets
successively fed to a scanner part.
[0004] 2. Description of the Related Art
[0005] When a conventional image scanning apparatus scans both
sides of an original document, its scanner part first scans a front
side. The original document is then transferred in a paper path to
a space above a discharged paper receiving tray (first paper path)
by discharge rollers, and the discharge rollers that nip an end of
the original document are caused to rotate in a reverse direction
so that the document is moved backward and introduced into another
paper path (second paper path) to turn the document upside down.
After that, the document is sent to the scanner part again such
that a back side of the document is scanned. Subsequent to this,
the document is discharged into the discharge tray.
[0006] After reversing the document feed direction in the
conventional image scanning apparatus, the document is transferred
into the second paper path, as mentioned above. For this reason, a
guide member is generally disposed at a branching point between the
first and second paper paths. The guide member is a switching
member to determine which paper path should be used.
[0007] The original document is discharged on the discharge tray
with its front side being up. In other words, the first page is up
and the second page down. Therefore, when two original sheets of
paper are discharged on the tray, page 1 (front side of the first
sheet) faces page 4 (back side of the second sheet).
[0008] In order to overcome this problem, the original sheet is
reintroduced into the paper path after both the two sides of the
original sheet are scanned, so that the original sheet is turned
upside down again. In this case, however, no scanning is performed.
The original paper is then discharged onto the discharge tray.
[0009] As a result, page 1 is down, page 2 is up, page 3 is down
(so that it contacts page 2), and page 4 is up (in case of the
two-sheet scanning).
[0010] In this conventional arrangement, however, the original
document has to pass the scanning part three times, i.e., when its
front side is scanned, back side is scanned and the document is
turned upside down without scanning. Accordingly, the scanning
operation takes a relatively long period as a whole.
[0011] Further, when the original paper passes over the scan part
for the third time, no scanning operation is conducted. During this
action, therefore, the scanner part is occupied by the original
paper without scanning operation, and it is not possible to feed
the next original paper to the scan part. Accordingly, the scanning
speed of the machine is lowered as a whole.
[0012] Moreover, the guide member located at the branching point
between the first and second paper paths is driven by an
electrically controlled element such as a solenoid when it is
switched to connect the first or second paper path to the paper
discharge exit. It is required to synthesize rotating movements of
paper feed roller(s) with the switching movement of the guide
member. This makes the paper feed control complicated.
SUMMARY OF THE INVENTION
[0013] An object of the present invention is to provide an image
scanning apparatus that can eliminate the above-described
problems.
[0014] One concrete object of the present invention is to reduce
the time needed to scan both sides of an original document.
[0015] Another concrete object of the present invention is to drive
a guide member disposed at a paper path branching point without
employing a complicated control program.
[0016] According to one aspect of the present invention, there is
provided an image scanning apparatus comprising: a scanner; a
document feeder for receiving sheets in a stack and feeding one
sheet at a time; an inverting path for turning a sheet, which is
fed from the document feeder, upside down before scanning; a
transportation means located at a downstream end of the inverting
path for reversing a transportation direction of the sheet and
feeding the sheet to the scanner through a return path; a reversing
means for reversing the transportation direction of the sheet after
the scanner scans one side of the sheet, and feeding the sheet to
the scanner again to scan the other side of the sheet; and a
discharging means for discharging the sheet after the two sides of
the sheet are scanned. The sheet is substantially turned upside
down when its transportation direction is reversed and fed to the
scanner for the second time.
[0017] A guide member may be located a bifurcation of the return
path and the inverting path for opening one of the return and
inverting paths and closing the other of the return and inverting
paths, whereby it is possible to introduce the sheet into the
return path after the sheet is fed towards the scanner from the
downstream end of the inverting path.
[0018] The transportation means may include at least one roller,
and the reversing means may include at least one roller. The guide
member may pivot as the transportation means rotates. The guide
member may be operatively connected to the transportation means via
a torque limiter.
[0019] Three rollers may be arranged to form two pairs of rollers,
and one of the two pairs of rollers may constitute the
transportation means whereas the other pair of rollers may
constitute the reversing means. The latter pair of rollers may also
constitute the discharging means.
[0020] Alternatively, two rollers may only be arranged to
constitute all of the transportation means, reversing means and
discharging means.
[0021] Additional objects, aspects, benefits and advantages of the
present invention will become apparent to those skilled in the art
to which the present invention pertains from the subsequent
detailed description and the appended claims, taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0022] FIG. 1 illustrates a perspective view of a facsimile machine
incorporating an image scanning device according to a first
embodiment of the present invention;
[0023] FIG. 2 illustrates a lateral cross sectional view of the
facsimile machine shown in FIG. 1;
[0024] FIG. 3 illustrates an enlarged lateral cross sectional view
of ADF used in the facsimile machine shown in FIG. 1;
[0025] FIG. 4 illustrates a lateral view of a second guide member
and associated elements;
[0026] FIG. 5 illustrates a plan view of the second guide member
and associated elements shown in FIG. 4;
[0027] FIG. 6 illustrates a lateral view of a gear train;
[0028] FIG. 7 is a block diagram of the image scanning device;
[0029] FIG. 8 is a flowchart showing an operation of the image
scanning device according to the first embodiment;
[0030] FIG. 9 is a flowchart particularly illustrating an initial
stage of the operation of the image scanning device;
[0031] FIG. 10 is a flowchart showing a second stage of the
operation of the image scanning device;
[0032] FIG. 11 illustrates a third stage of the operation;
[0033] FIG. 12 illustrates a front half of a control loop according
to the first embodiment;
[0034] FIG. 13 illustrates a second half of the control loop;
[0035] FIG. 14 illustrates a final stage of the operation;
[0036] FIG. 15 illustrates a lateral cross sectional view of ADF
according to a second embodiment of the present invention;
[0037] FIG. 16 illustrates a flowchart of an operation performed by
an image scanning device of the second embodiment;
[0038] FIG. 17 is a flowchart illustrating a first stage of the
operation;
[0039] FIG. 18 illustrates a flowchart of a second stage of the
operation;
[0040] FIG. 19 illustrates a flowchart of a third stage of the
operation;
[0041] FIG. 20 illustrates a flowchart of a fourth stage of the
operation; and
[0042] FIG. 21 illustrates a flowchart of a final stage of the
operation.
DETAILED DESCRIPTION OF THE INVENTION
[0043] Embodiments of the present invention will now be described
in reference to the accompanying drawings. In the following
description, a facsimile machine is employed as an image scanning
apparatus of the present invention.
[0044] Referring to FIGS. 1 and 2, illustrated is a facsimile
machine that includes a scanner part 1 and a printer part 2 below
the scanner part. The printer part 2 includes a printer module 3
and a paper cassette 4 below the printer module. Sheets stacked in
the paper cassette 4 are transferred to the printer module 3, and
discharged onto a discharge tray 5 after printing.
[0045] The scanner part 1 has a casing 10, and a hinge 10b
extending from a lower surface of the casing 10 engages on a hinge
pin 1a of the printer part 2. The scanner part 1 can therefore
pivot up and down relative to the printer par 2 about the hinge pin
1a.
[0046] The scanner part 1 includes a scanner module 6 in the casing
10. A transparent stationary document loading bed 11 lies over the
casing 10. An original document placed on the transparent bed 11 is
scanned by the scanner module 6 that moves from a start position
indicated by the solid line to an end position indicated by a
phantom line in FIG. 2.
[0047] A document cover 7 lies over the bed 11 such that it can
pivot up and down about one edge thereof. The original document
situated on the transparent bed 11 is pressed by the document cover
7 from the top.
[0048] An automatic document feeder (ADF) 8 is attached near the
edge of the document cover 7. An outer contour or appearance of ADF
8 is defined by the document cover 7 and a pair of side frames 7a
and 7b as shown in FIG. 1. The document cover 7 and side frames 7a,
7b are arranged side by side in a direction perpendicular to the
scanning direction. Between the side frames 7a and 7b, disposed is
an ADF cover 14 that covers a main mechanism of ADF 8. The ADF
cover 14 is openable. Metallic plates (not shown) stand inside the
side frames 7a and 7b such that they support ends of feed rollers.
The cover 7 and one or both of the side frames 7a and 7b house in
combination a drive source (e.g., motor) adapted to rotate drive
rollers (e.g., paper feed rollers) and associated parts such as
chains, sprockets, gears, etc.
[0049] ADF 8 includes an outer frame constituted by the cover 7 and
side frames 7a and 7b, and a document feeder part located inside
the outer frame and covered with the ADF cover 14.
[0050] An original paper feed tray 9 is disposed above the document
cover 7 such that it continues to a paper inlet 8a of ADF 8. An
original paper discharge tray 7c lies below the original paper feed
tray 9. This tray 7c defines an upper surface of the document cover
7 and is continuous to an outlet opening 8b of ADF 8, which opens
below the paper inlet 8a. Thus, a paper path is formed inside ADF 8
such that it extends from the paper inlet 8a to the outlet 8b.
[0051] Referring to FIG. 3, original sheets piled on the feed tray
9 are picked up by the feed roller 21 and transmitted to the paper
inlet 8a. When the sheets are transported to a separate roller 22
and a retard roller 23, they are separated sheet by sheet and
further transported along the paper path by the separate roller 22,
feed roller 25 and giant feed roller 28 up to a platen glass 12.
The original sheet passing over the platen glass 12 is scanned by
the scanner 6 which is situated at the initial position as
indicated by the solid line. The original sheet is then transmitted
to the discharge tray 7c through the discharge opening 8b.
[0052] The scanner part 1 can therefore be used as a flat bed
scanner that scans a stationary original document with a moving
scanner 6 and a sheet feed scanner that scans a moving original
document with a stationary scanner 6.
[0053] Referring to FIG. 1, the scanner casing 10 has an operation
panel 13 with a number of keys and buttons. By pressing these keys,
a user can instruct the machine to scan an original document and
enter a facsimile (or telephone) number so as to transmit the
scanned image to a remote machine via facsimile. The user is also
able to instruct the printer 3 to print the scanned image. Of
course, the user can instruct the machine to perform other
functions.
[0054] The inside structure of ADF 8 will be described. In the
following description in reference to FIG. 3, the "forward
position" is a position of the paper inlet 8a or that of the outlet
8b (i.e., rightward position), and the "backward position" is a
position of a 180-degree turning portion of the paper path (i.e.,
leftward position). The original paper moves from the forward
position (8a) toward the backward position and returns to the
forward position (8b). Directions perpendicular to the drawing
sheet are right and left directions. It should be assumed that the
ADF cover 14 is closed and nothing is placed on the transparent bed
11 with the document cover 7 put on the top of the scanner casing
10 as shown in FIG. 2 unless otherwise mentioned.
[0055] First, the paper path will be described. As shown in FIG. 3,
a first "C" shaped paper path R1 extends from the paper inlet 8a to
a roller 33 in ADF when viewed laterally, and a discharge path R3
extends from the roller 33(or platen glass 12) to the paper outlet
8b. Downstream of the separate roller 22, provided are feed rollers
24 and 25 for transmitting the original paper in the first paper
path R1 from the nip between the separate roller 22 and retard
roller 23. A roller 27 is a first press roller.
[0056] A feed roller 28 is disposed at the end of the first paper
path R1 and the beginning of the discharge path R3. The feed roller
28 is on the platen glass 12. An extra roller 26 and a second press
roller 29 are disposed at the end of the paper discharge path R3.
These rollers 26 and 29 contact each other.
[0057] A return path R4 extends from the end of a second paper path
R2 towards the feed roller 28 and connects to the first paper path
R1. A conjunction path R5 extends from the end of the discharge
path R3 and meets the return path R4. The second press roller 29 is
lifted up and down by a cam mechanism (not shown) so that it can
contact and leave the extra roller 26.
[0058] The second paper path R2 serves as an inverting means for
turning the document upside down prior to scanning when the
document is fed from the paper inlet 8a. The extra roller 26 and
first press roller 27 is a transportation means for transporting
the turned document in a reverse direction such that the document
reaches the platen glass 12. The giant feed roller 28 and slave
rollers 31 to 33 constitute in combination a guide means for
introducing the original document to the platen glass 12. The extra
roller 26 and second press roller 29 serve as a reverse feeding
means for reversing the transportation direction of the original
document after one side of the original document is scanned on the
platen glass 12, such that the original document is transported to
the platen glass 12 again.
[0059] The rollers 22, 25, 26 and 28 are driven by the drive
source(s) and associated power transmission mechanism(s) disposed
in one or both of the side frames 7a and 7b. Thus, these rollers
22, 23, 25, 26 and 28 are drive rollers, and the rollers 24, 27,
29, 31, 32 and 33 are trailing or driven rollers.
[0060] A first guide member 37 is installed at a position
downstream of the nip between the slave feed roller 24 and master
feed roller 25, i.e., at a branching position of the first and
second paper paths R1 and R2. The first guide member 37 can pivot
up and down about a pivot center (shaft) 37a so that one of the
paper paths R1 and R2 is blocked by the first guide member 37 and
the paper can proceed in the other paper path. When a user presses
certain function keys 18 and/or other keys on the control panel 13
(FIG. 1) to bring the machine into a one-side scanning mode, the
first guide member 37 pivots downwards to a lower position A, and
the document is transmitted to the first paper path R1. On the
other hand, when a user selects a both-side scanning mode, the
first guide member 37 pivots to an upper position B, and the
document is introduced to the second paper path R2.
[0061] On the shaft 27a of the first press roller 27, disposed is a
second guide member 38 that can pivot to a lower position C or an
upper position D. The position C interrupts passage of the
document, and the position D allows passage.
[0062] Between the extra roller 26 and giant feed roller 28, the
third paper path R3 and return path R4 are connected to each other
by a fifth paper path R5. A third guide member 39 is provided below
the fifth paper path R5. The third guide member 39 pivots up and
down about a shaft 39a so as to control passage of the document.
Specifically, when the third guide member 39 is moved to a lower
position E, the third paper path R3 is closed, and the document is
forced to move in the fifth paper path R5. When the third guide
member 39 is moved to an upper position F, on the other hand, the
fifth paper path R5 is closed and the document moves in the third
paper path R3.
[0063] The third guide member 39 may be a flexible member such as
film. It is also satisfactory that the third guide member 39 is
closed and opened by its deadweight.
[0064] A first position sensor 35 is disposed on the second paper
path R2 between the nip of the slave feed roller 24 and master feed
roller 25 and the nip of the extra roller 26 and first press roller
27, and a second position sensor 36 is disposed near a merge of the
first paper path R1 and return path R4 so as to detect the paper
passing thereover respectively.
[0065] A first angle sensor 46 is incorporated in a rotating shaft
26a of the extra roller 26, and a second angle sensor 48 is
incorporated in a rotating shaft 28a of the giant feed roller 28 so
as to detect angular positions of the respective rollers.
[0066] A controller 40 of the image scanning machine will now be
described.
[0067] Passage of the document is controlled by the controller 40
shown in FIG. 7. The controller 40 is connected to sensors and
other elements as described below.
[0068] Each of the sensors 35 and 36 is an optical sensor or limit
switch, that includes a light emitting element located on one side
of the paper path and a light receiving element on the other side.
Each of these sensors detects the passing period of the document
and issues a control signal (detection signal) to the controller
40.
[0069] Each of the sensors 46 and 48 is an angular sensor such as a
potentiometer, and detects an angular position of the associated
roller. When the roller comes to a certain angular position, the
sensor issues a detection signal to the controller 40
[0070] The guide rollers 37 and 39 receive control signals
(switching signals) from the controller 40 and are caused to move
to the upper or lower positions respectively so as to change the
moving direction of the document.
[0071] The drive source 41 and associated power transmission
mechanism 42 for the rollers 22, 23, 25, 26 and 28 activate or
deactivate these rollers on the basis of control signals from the
controller 40. In particular, the extra roller 26 can be rotated in
both directions.
[0072] A lift mechanism of the second press roller 29, which
includes a cam mechanism and other elements, can move up and down
in accordance with control signals from the controller 40.
[0073] The control panel 13 shown in FIG. 1 includes the function
keys 18 for selecting a scanning mode such as the one-side or
both-side scanning mode, a start button 19 for starting the
scanning operation, a stop button 16 for discontinuing the scanning
operation while a plurality of sheets are being scanned, and other
keys. As a user presses these keys, a control signal is sent to the
controller 40.
[0074] Referring now to FIGS. 8 and 9, will be described a document
turning mechanism.
[0075] As shown in FIG. 9, a user first loads an original document
into the paper tray 9, with the front side of the document being
up. The user then operates the function keys 18 to select the
both-side scanning mode (Step S1). The controller 40 produces and
sends a control signal to the guide members 37 and 39 such that the
guide members 37 and 39 are moved to the upper positions B and F
respectively (Step S2).
[0076] When the use presses the start button 19 on the control
panel 13 (Step S3), the controller 40 issues a control signal to
the drive 41 and transmission mechanism 42 of the extra roller 30
and other rollers 22, 25, 26 and 28. The extra roller 26 is then
caused to rotate in a normal direction (clockwise in FIG. 3) (Step
S4), and the pick-up roller 21, separate roller 22 and retard
roller 23 cause the uppermost sheet (first original document) to
separate from the paper stack and proceed into the paper path
through the paper inlet 8a. This original document is further
transported by the master feed roller 25 and slave feed roller 24
into the second paper path R2 (Step S5).
[0077] When the first original document reaches the paper exit 8c,
it is moved to a space above the discharge tray 7c by the extra
roller 26 and first press roller 27. As the first position sensor
35 detects passage of the end of the first original document (Step
S6), it issues a detection signal to the controller 40. Then, the
controller 40 outputs a control signal to the extra roller 26 such
that the extra roller 26 rotates in a reverse direction.
[0078] When the first position sensor 35 detects the complete
passage of the first original sheet, the controller 40 further
controls the rotation (first rotation angle) of the extra roller 26
such that the end of the first original sheet is moved from the
position of the first position sensor 35 to a position between the
second guide member 38 and the nip of the extra roller 26 and first
press roller 27. As shown in FIG. 10, specifically, after the first
angular sensor 46 detects the first rotation angle (Step S7) and
most of the first original sheet is discharged from the paper exit
8c, the extra roller 26 is rotated in the reverse direction
(counterclockwise in FIG. 3) (Step S8). In this situation, the end
of the first original sheet is only nipped with the extra roller 26
and first press roller 27. Simultaneously, the second guide member
38 is switched to the lower position C such that the original sheet
can be introduced to the return path R4 (Step S9). The original
sheet is transported in the opposite direction by the extra roller
26 and first press roller 27.
[0079] The first original sheet that moves backwards is caught by
the giant feed roller 28 and first press roller 31. When the
"front" end (this end is the "rear" end previously) of the first
original sheet is detected by the second sensor 36 (Step S10), a
detection signal is sent to the controller 40. The controller 40
then instructs the scanner 6 to start the scanning operation.
[0080] As the second position sensor 36 detects passage of the
front end of the first original sheet, the controller 40 uses the
second angular sensor 48 to calculate a rotation angle (second
rotation angle) of the giant feed roller 28 corresponding to the
moving distance of the front end of the sheet from the position of
the second sensor 36 to the rear end of the platen glass 12. When
this second rotation angle is reached (Step S11), the scanning of
the back side of the first original sheet is started (Step
S12).
[0081] As illustrated in FIG. 11, the first original sheet is moved
by the giant feed roller 28 and second slave roller 32 or third
slave roller 33. When passage of the rear end of the first original
sheet is detected by the second positional sensor 36 (Step S13),
the detection signal is sent to the controller 40. The controller
40 then issues a control signal to the scanner 6 to terminate the
scanning. After that, the controller 40 issues control signals to
the extra roller 26, third guide roller 39 and the power
transmission mechanism 42 of the drive source 41 respectively.
[0082] As the second position sensor 36 detects the complete
passage of the first original sheet, the controller 40 uses the
angular sensor 48 to measure a rotation angle (third rotation
angle; greater than the second rotation angle) of the giant feed
roller 28 corresponding to the moving distance of the sheet rear
end from the second position sensor's position to the front end of
the platen glass 12, and a rotation angle (fourth rotation angle)
of the giant feed roller 28 corresponding to the moving distance of
the sheet rear end from the second position sensor's position to a
mid point between the third guide member 39 and the nip of the
extra roller 26 and second press roller 29. When the third rotation
angle is reached (Step S14), the scanning of the back side of the
first original sheet is finished (Step S15).
[0083] When the fourth rotation angle is detected by the angular
sensor 38 (Step S16), most of the first original sheet is
discharged from the exit 8b and the rear end of the sheet is only
nipped between the extra roller 26 and the second press roller 29.
At this point, the extra roller 26 is caused to stop rotating (Step
S17). Further, the third guide member 39 is switched to the lower
position E in order not to allow the sheet to move reversally
toward the third slave roller 33 (Step S18).
[0084] In this situation, the pick-up roller 21, separate roller 2
and retard roller 23 pick up a currently uppermost sheet (second
original sheet) from the paper stack and feed it into the paper
path from the inlet 8a (Step S19). The extra roller 26 starts
rotating in the normal direction (clockwise in FIG. 3) (Step S20).
This sheet is further transported by the master feed roller 25 and
slave feed roller 24 so that the sheet reaches the second paper
path R2. Here, the front end of the second original sheet is
detected by the first position sensor 35 (Step S21), and the sheet
is further transported by the extra roller 26 and first press
roller 27 such that it is discharged from the exit 8c into the
space above the discharge tray 7c.
[0085] As the extra roller 26 rotates in the normal direction at
Step S20, the first original sheet is also transported backwards;
it moves in the fourth paper path R4 and caught by the giant feed
roller 28 and first slave roller 31. When the front end of the
first original sheet (this end is the rear end before the second
backward movement, i.e., the front end at the time of loading into
the paper inlet 8a is again the front end) is detected by the
second position sensor 36 (Step S22), the detection signal is sent
to the controller 40. The controller 40 then instructs the lift
mechanism 43 of the second press roller 29 to move down and the
scanner 6 to scan the sheet. The controller 40 then immediately
instructs the third guide member 39 to move to the opposite
position.
[0086] In this manner, the second press roller 29 is moved down so
that it is separated from the extra roller 26 (Step S23). If the
length of the sheet is greater than the total lengths of the paper
paths R5, R4 and R3, the front end of the sheet reaches or returns
to the rollers 26 and 29 when the rear end of the same sheet is
still nipped between the rollers 26 and 29. In order to allow the
front end of the sheet to move further, the rollers 26 and 29 are
spaced from each other. After Step S23, the sheet front end can
smoothly pass between the rollers 26 and 29. The sheet is
transported by the rollers 28 and 31 even after a gap is created
between the rollers 26 and 29.
[0087] The controller 40 causes the angular sensor 48 to count the
rotation angle of the giant feed roller 28 upon detecting the front
end of the first original sheet by the second position sensor 36.
When the second rotation angle is reached (Step S24), the scanning
of the front side of the first original sheet begins (Step S25).
The controller 40 soon issues a control signal to the third guide
member 39 such that the third guide member moves to the upper
position F (Step S26).
[0088] After that, the first original document is transported by
the giant feed roller 28 and second slave roller 32 or third slave
roller 33. When the second position sensor 36 detects passage of
the rear end of the first original document (Step S27), the
controller 40 causes the angular sensor 48 to measure the rotation
angle of the giant feed roller 28. When the third rotation angle is
reached (Step S28), a control signal is issued to the scanning unit
6 to stop the scanning so that the scanning of the front side of
the first original document is complete (Step S29).
[0089] While the first original document is being scanned, the
second original document is transported in the second paper path R2
toward the exit 8c. As shown in FIG. 13, when passage of the rear
end of the second original document is detected by the first
position sensor 35 (Step S30), a detection signal to sent to the
controller 40. The controller 40 then issues a control signal to
the extra roller 26 and the lift mechanism 43 of the second press
roller 32.
[0090] Upon receiving the detection signal indicative of the
passage of the rear end of the first original document from the
first position sensor 35, the controller 40 causes the first
angular sensor 46 to measure the rotation angle of the extra roller
36. When the measured rotation angle reaches the first rotation
angle (Step S31), most of the second original document is
discharged from the paper exit 8c and the rear end of the second
original document is only nipped between the extra roller 26 and
first press roller 27. In this situation, the extra roller 26 is
caused to rotate in the reverse direction (counterclockwise in FIG.
3) (Step S32), and at the same time the second guide member 38 is
switched to the lower position C in order to feed the second
original document in the return path R4 (Step S33). The second
original document is moved backwards by the extra roller 26 and
first press roller 27, and the second pres roller 32 is moved up to
contact the extra roller 26 (Step S34).
[0091] The program returns to Step S10 to perform the scanning
operation to the second original document. The scanning operation
itself is the same as that applied to the first original
document.
[0092] The first original document is further transported towards
the discharge tray 7c by the extra roller 26 and second press
roller 29 since the extra roller 26 starts rotating in the reverse
direction at Step S32.
[0093] In this manner, as the front side of the preceding document
is scanned completely, the scanning to the back side of the current
original document is immediately initiated. Thus, a plurality of
documents are successively scanned. It should be noted, however,
that the flowchart for transportation of the last original document
is different.
[0094] Specifically, when the program arrives at Step S21 in FIG.
11 for the last original sheet, the first position sensor 35 does
not function since there is no next sheet. Thus, the program ends
when the front side of the last original sheet is completely
scanned. If the first original sheet is the last original sheet,
the program executes the below described process after executing
Steps S1 through S21.
[0095] A flowchart for the last original sheet will be described.
For example, if the first position sensor 35 does not detect
passage of the original sheet within a predetermined period (Step
S21), i.e., while the controller 40 measures the fourth rotation
angle of the giant feed roller 28 with the angular sensor 48 at
Step S16 in FIG. 11, and further measures a predetermined angle,
then the last original sheet moved backward at Step S20 proceeds in
the fifth paper path R5 and is transported by the giant feed roller
28 and first slave roller 31. When the front end of the last
original sheet is detected by the sensor position sensor 6 (Step
S35), a detection signal is output to the controller 40 as shown in
FIG. 14. The controller 40 instructs the second press roller lift
mechanism 43 to move downward and the scanner 6 to start scanning.
Immediately thereafter, the controller 40 instructs the third guide
member 39 to switch to the other position.
[0096] The second press roller 29 is lowered so that the extra
roller 26 is separated from the second press roller 29 (Step
S36).
[0097] The controller 40 measures the rotation angle of the giant
feed roller 28 using the angular sensor 48 as the second position
sensor 36 detects the front end of the last original sheet. When
the second rotation angle is reached (Step S37), the scanning of
the front side of the last original sheet is started (Step S38).
The controller 40 immediately issues a control signal (switching
signal) to the third guide member 39 such that the third guide
member 39 moves to the upper position F (Step S39).
[0098] The last original sheet is transferred by the giant feed
roller 28 and second slave roller 32 or third slave roller 33. When
the second position sensor 36 detects passage of the rear end of
the last original sheet (Step S40), a detection signal is sent to
the controller 40. The controller 40 then issues control signals to
the extra roller 36 and second press roller lift mechanism 43
(lifting command) and issues a control command to the scanner 6
(scanning termination command).
[0099] The extra roller is caused to rotate in the reverse
direction (counterclockwise in FIG. 3) (Step S41) and the second
press roller 29 is moved upward such that it contacts the extra
roller 26 again (Step S42). When the second position sensor 36
detects passage of the rear end of the first original sheet, the
controller 40 measures the rotation angle of the giant feed roller
28 using the angular sensor 48. When the third rotation angle is
reached (Step S43), the scanning to the last original sheet is
completed (Step S44).
[0100] The last original sheet is then moved to the discharge tray
7c by the extra roller 26 and second press roller 29.
[0101] Finally, the controller 40 stops all the rollers after a
predetermined period (Step S45). Specifically, the controller 40
deactivates the rollers after it measures the fourth rotation angle
of the giant feed roller 28 with the angular sensor 48 and further
measures a predetermined rotation.
[0102] Because the sheet is turned upside down at the initial stage
of the sheet transportation process prior to the scanning, and then
fed to the scanner 2, the sheet is required to pass over the platen
glass 12 only twice. As a result, the total scanning period needed
to scan both sides of the sheet is reduced. Further, the sheet
placed on the feed tray 9 with its front side up, but its back side
is first scanned. Then, the sheet is turned upside down and its
front side undergoes the scanning. The sheet is discharged onto the
discharge tray with its front side down. A next sheet is stacked on
the first sheet. Thus, the sheets are piled up on the discharge
tray in the decent order, i.e., page 2 of the first sheet contacts
page 3 of the second sheet.
[0103] The sheet fed from the feed tray 9 is turned upside down
when it proceeds in the second paper path R2. The sheet is then
transported backwards by the extra roller 26 and second press
roller 29 and proceeds in the return path R4 such that it advances
to the platen glass 12 (i.e., scanner). The sheet is further nipped
by the giant feed roller 28 and slave rollers 31, 32 and 33 and
guided properly to the platen glass 12. Therefore, the sheet does
not approach the platen glass 12 from the upper diagonal direction.
This prevents degraded scanning and jamming.
[0104] If the original sheet is long, the front and rear ends of
the original document after the first side scanning are transported
by the extra roller 26 and second press roller 29 (both of them are
the reversing means) and the extra roller 21 and first press roller
27 (both of them are the transportation means). After the second
side scanning, on the other hand, the front and rear ends of the
original sheet are transported by the extra roller 26 and second
press roller 29 (both of them are the reversing means). Further,
the transportation directions are opposite each other. In the
illustrated embodiment, therefore, the extra roller 26 and first
press roller 27 (transportation means) are made always contact each
other whereas the extra roller 26 and second press roller 29
(reversing means) can contact and leave each other.
[0105] In this manner, the extra roller 26 is separated from the
second press roller 29, and the front and rear ends of the original
sheet after the second side scanning are transported by other
rollers 28, 31, 32, 33. The rollers 26 and 29 should be spaced from
each other when the length of the sheet is greater than the total
length of the paper paths R5, R4 and R3.
[0106] In order to cause the extra roller 26 and second press
roller 29 to contact and leave each other, however, the lift
mechanism 43 including the motors and cams or an electromagnetic
lift mechanism including solenoids should be employed. This would
raise the manufacturing cost.
[0107] In this embodiment, therefore, the lift mechanism 43 or the
electromagnetic elevator is used to the minimum. Specifically, the
extra roller 26 and second press roller 29 which constitute the
reversing means are only made contact and separate. This
contributes to the cost reduction.
[0108] The second guide member 38 located at the bifurcation of the
second paper path R2 and return path R4 for switching the moving
direction of the sheet will be described.
[0109] Referring to FIGS. 4 to 6, the first press roller 27 in
press contact with the rotating extra roller 26 rotates about the
shaft 27a. The second guide member 38 is also pivotable about the
roller shaft 27a. By this pivot movement, the second guide member
38 can move between the positions "c" and "d".
[0110] The first press roller 27 and roller shaft 27a rotate
together, and the roller shaft 27a and second guide member 38 are
operatively connected to each other by a gear assembly 51 and a
torque limiter 61.
[0111] The gear assembly 51 includes a first gear 52 rotating with
the roller shaft 27a, a second gear 53 engaging with the first gear
52 and a third gear 54 engaging with the second gear 53. The
rotation center of the third gear 54 coincides with the roller
shaft 27a. The third gear is an internal gear.
[0112] Ends of the roller shaft 27a are rotatably supported by the
frame 8d of ADF 8, and a shaft 53a of the second gear 53 is also
rotatably supported by the frame 8d.
[0113] In the gear train 51, the rotations of the roller shaft 27a,
e.g., leftward rotations of the first gear 52, cause the second
gear 53 in mesh with the first gear 52 to rotate rightwards, and
the third gear 54 in mesh with the second gear 53 to rotate
rightwards. That is, the first gear 52 and third gear 54 rotate in
the opposite directions.
[0114] The torque limiter 61 includes a casing 62 rotatably
supported by the roller shaft 27a, a biasing member 63 rotatably
fitted on the roller shaft 27a inside the casing 62, a compression
spring 64 located between the casing 62 and biasing member 63 for
biasing the biasing member 63 to the second guide member 38, and a
friction member 65 located between the biasing member 63 and second
guide member 38.
[0115] The friction member 65 is forced against the lateral face of
the second guide member 38 by the compression spring 64 and biasing
member 63. The casing 62 of the torque limiter 61 is operatively
connected to the third gear 54 of the gear train 51 such that they
can rotate together.
[0116] The gear mechanism 51 and torque limiter 61 have the above
described structures. When, for example, the extra roller 26
rotates in the direction p1 and the first press roller 27 trails
and rotates in the direction q1, then the first gear 52 rotating
with the roller shaft 27a rotates in the direction q1, and the
third gear 54 rotating opposite the first gear 52 rotates in the
direction q2 together with the casing 62 of the torque limiter 61.
When the torque limiter casing 62 rotates in the direction q2, the
biasing member 63 biased to the second guide member 38 by the
compression spring 64 also rotates in the direction q2.
[0117] Between the biasing member 63 and second guide member 38,
exerted is a constant friction force by the friction member 65.
This friction force causes the second guide member 38 to rotate in
the direction q2 (i.e., upwards) as the biasing member 63 rotates
in the direction q2.
[0118] When the second guide member 38 pivots upwards and reaches
the position "d", it hits an upper stop pin 38b (FIG. 4) located
above and cannot move further upwards.
[0119] A force exerted by the upper stop pin 38b that prohibits the
second guide member 38 from pivoting further upward is greater than
an upward pivoting force applied to the second guide member 38 by
the friction force from the friction member 65. Thus, the second
guide member 38 stops pivoting at the position "d", and the biasing
member 63 keeps rotating in the direction q2 together with the
casing 62.
[0120] Specifically, as the extra roller 26 is caused to rotate in
the direction p1 and the first press roller 27 is caused to rotate
in the direction q1, the torque limiter 61 forces the second guide
member 38 to pivot upwards from the position "c" to the position
"d".
[0121] If the extra roller 26 rotates in the direction p2 and the
first press roller 27 trails it and rotates in the direction q2, on
the other hand, the third gear 54 of the gear train 51 rotates in
the direction q1 together with the torque limiter casing 62, and
the second guide member 38 pivots from the position "d" to the
position "c" with the friction force of the friction member 65. The
second guide member 38 abuts on the lower stop pin 38a provided
below the second guide member 38 when it reaches the position
"c".
[0122] As described above, the second guide member 38 pivots
upwards from >the position "c" to the position "d" as the extra
roller 26 pivots in the direction p1, and pivots downwards from the
position "d" to the position "c" as the extra roller 26 pivots in
the direction p2. In this manner, the changing rotating direction
of the extra roller 26 switches the pivoting direction of the
second guide member 38 and closes/opens the second paper path
R2.
[0123] Thus, the second guide member 38 pivots up and down
depending upon the rotating direction of the extra roller 26, which
serves as the roller for reversing the feeding direction of the
original sheet, so as to open and close the second paper path R2.
Consequently, the paper proceeds in the second paper path R2 or
return path R4. The original sheet moving backward in the second
paper path R2 eventually reaches the end of the second paper path,
and then introduced to the scanner 6 through the return path R4. In
order to cause the original sheet to proceed in the return path R4,
changing the rotation direction of the extra roller 26 is only
required. This simplifies the paper path switching operation.
[0124] Since the second guide member 38 and extra roller 26 are
operatively connected to each other via the first press roller 27,
gear train 51 and torque limiter 61, and the change of the pivoting
direction of the second guide member 38 in accordance with the
rotating direction of the extra roller 26 is realized by the
mechanical structures such as the gear train 51 and/or torque
limiter 61, it is not necessary to drive the second guide member 38
in synchronization with the extra roller 26 or other elements. In
other words, electrical and electronic controls are not needed for
the synchronous operation. Accordingly, a program control applied
to the paper feed apparatus 12 can be simplified.
[0125] Therefore, the original sheet transported in the second
paper path R2 can easily be transferred to the scanner 6.
[0126] The structure of ADF 8 according to a second embodiment of
the present invention will now be described. It should be noted
that similar reference numerals are used to designate similar
elements in the first and second embodiments.
[0127] Referring to FIG. 15, first will be described the
transportation of the sheets. ADF 8 has a first paper path R1 which
extends from the paper inlet 8a to the paper outlet 8b and is
generally shaped "C" as viewed laterally, and a second paper path
R2' which is generally shaped ".epsilon." between the paper inlet
8a and outlet 8b. The extra roller 26 is disposed near the paper
exit 8b, and the press roller 29 is disposed below the extra roller
26. The nip between the separate roller 22 and retard roller 23 is
situated near the paper inlet 8a. A pair of swingable arms 20
extend forwards (to the right in the drawing) from ends of the
separate roller 22 such that they support a pick-up roller 21 at
their free ends. A nip between the slave feed roller 24 and master
feed roller 25, a nip between the extra roller 26 and press roller
29, a nip between the giant feed roller 28 and first slave roller
31, a nip between the giant feed roller 28 and second slave roller
32, a nip between the giant feed roller 28 and third slave roller
33, and a nip between the extra roller 26 and press roller 29 are
arranged in turn along the second .epsilon.-shaped paper path R2'
from the paper inlet 8a to the paper exit 8b.
[0128] The pick-up roller 21, separate roller 22, retard roller 23
and other elements function in combination to separate original
sheets stacked on the paper feed tray 9 one sheet at a time and
feed it to the paper path from the paper inlet 8a.
[0129] An upper half of the second paper path R2' is a means for
turning the original sheet upside down prior to scanning. The extra
roller 26 and press roller 29 is a means for reversing the
transferring direction of the turned sheet to feed the sheet to the
platen glass 12. The extra roller 26 also serves as a means for
reversing the transferring direction of the sheet after scanning at
the platen glass 12 such that the sheet proceeds to the platen
glass 12 again. The giant feed roller 28 and slave rollers 31, 32
and 33 constitute in combination a means for guiding the original
sheet to the platen glass 12.
[0130] Shafts 25a, 26a and 28a of the master feed roller 25, extra
roller 26 and giant feed roller 28 are fixedly supported by the
lateral plates of the ADF main housing at their ends respectively,
and the rollers 22, 25, 26 and 28 are driven by the drive source
and power transmission mechanism installed inside one or both of
the lateral frames 7a and 7b. Thus, the rollers 22, 25, 26 and 28
are drive rollers, and the rollers 24, 29, 31, 32 and 33 are driven
(or trailing) rollers that rotate with the drive rollers.
[0131] The first guide member 37 is disposed slightly downstream of
the nip of the slave feed roller 24 and master feed roller 25.
Specifically, the first guide member 37 is located at a first
bifurcation of the first paper path R1 and second paper path R2'.
The first guide member 37 can pivot up and down about the shaft 37a
so that selection of the paper path can be made. Specifically, when
a user operates the function keys 18 on the control panel 13 to
decide which side of the sheet should be scanned, and selects the
one-side scanning mode, the first guide member 37 pivots to a lower
position A so that the sheet is transported into the first paper
path R1. If the user selects the both-side scanning mode, the first
guide member pivots to an upper position B so that the sheet
proceeds to the second paper path R2'.
[0132] The second guide member 38 is located at a second branching
point downstream of the first branching point in the second paper
path R2'. The second guide member 38 pivots to a lower position C
or an upper position D so as to regulate a moving direction of the
sheet.
[0133] The third guide member 39 is located at a third branching
point downstream of the second branching point (closer to the paper
exit 8b) in the second paper path R2'. The third guide member 39
pivots to a lower position E or an upper position F so as to
regulate a moving direction of the sheet.
[0134] The first position sensor 35 is provided at an appropriate
position in the second paper path R2' between the nip of the slave
feed roller 24 and master feed roller 25 and the nip of the extra
roller 26 and press roller 29 to detect passage of the sheet. The
second position sensor 36 is provided near the confluence of the
first paper path R1 and second paper path R2' to detect passage of
the sheet.
[0135] The shaft 26a of the extra roller 26 and shaft 28a of the
giant feed roller 28 incorporate the first and second angular
sensors 46 and 48 respectively to detect rotation angles of the
rollers.
[0136] The controller 40 of this embodiment is similar to the
controller 40 of the first embodiment. As illustrated in FIG. 7,
the controller 40 of the second embodiment is also connected to
various sensors, members and other elements.
[0137] The mechanism for turning the sheet upside down in this
embodiment will be described in detail in reference to FIGS. 16 to
21.
[0138] Referring to FIG. 17, a user first loads an original sheet
on the feed tray 9 with the front side of the sheet being up. Then,
the user operates the function keys 18 on the operation panel 13 to
select the both-side scanning mode (Step T1). The controller 40
issues control signals to the guide members 37, 38 and 39 to switch
their positions such that the first guide member 37 is caused to
pivot to the upper position B, the second guide member 38 to the
lower position C and the third guide member 39 to the lower
position E (Step T2).
[0139] As the user presses the start button 19 on the operation
panel 13 (Step T3), the controller 40 issues control signals to the
drive source 41 and power transmission mechanism 42 of the extra
roller 30 and other rollers 22, 25, 26 and 28. As a result, the
extra roller 26 rotates in the reverse direction (counterclockwise
in FIG. 15) (Step T4), and the pick-up roller 21, separate roller
22 and retard roller 23 in combination pick up the uppermost one of
the sheets (first original sheet) from the paper stack. The first
original sheet is then transferred to the paper path from the paper
inlet 8a, and further transported by the master feed roller 25 and
slave feed roller 24 towards the second paper path R2' (Step
T5).
[0140] The first original sheet is transferred to the space above
the discharge tray 7c from the paper exit 8b by the extra roller 26
and press roller 29. When the first position sensor 35 detects
passage of the rear end of the first original sheet (Step T6), a
detection signal is issued to the controller 40. The controller 40
then issues instruction signals to the second guide member 38 and
extra roller 26.
[0141] When the first position sensor 35 detects passage of the
rear end of the first original sheet, the controller 40 controls
the rotation angle of the extra roller 26 (first rotation angle)
such that the rear end of the sheet is further transported from the
position of the first position sensor 35 to a mid point between the
third guide member 39 and the nip of the extra roller 26 and press
roller 29. Specifically, as illustrated in FIG. 18, when the first
angular sensor 46 detects the first rotation angle (Step T7), most
of the sheet is discharged from the paper exit 8b and the rear end
of the sheet is only nipped between the extra roller 26 and press
roller 29. At this point, the second guide member 38 is switched to
the upper position D in order to prevent the sheet from moving
backwards towards the paper inlet 8a (Step T8). Simultaneously, the
extra roller 26 is caused to rotate in the normal direction
(clockwise in FIG. 15) (Step T9), and the first original sheet is
transferred in the opposite direction by the extra roller 26 and
press roller 29.
[0142] The first original sheet moving backwards is caught by the
giant feed roller 28 and first slave roller 31. When the front end
of the first original sheet is detected by the second position
sensor 36 (Step T10), a detection signal is sent to the controller
40. The controller 40 produces control signals to the lift
mechanism 43 of the press roller 29 and the scanner 6.
[0143] The press roller 29 is lowered to be spaced from the extra
roller 26 (Step T11). Therefore, the sheet front and rear ends can
smoothly move in opposite directions in a gap between the rollers
26 and 29.
[0144] When the second position sensor 36 detects passage of the
front end of the first original sheet, the controller 40 causes the
second angle sensor 48 to measure the rotation angle of the giant
feed roller 28 (second rotation angle), which corresponds to the
moving distance of the sheet front end from the position of the
second position sensor 36 to the rear end of the platen glass 12.
When the second rotation angle is reached (Step T12), the scanning
of the back side of the first original sheet is started (Step
T13).
[0145] Referring to FIG. 19, the first original sheet is
transported by the giant feed roller 28 and second slave roller 32
or third slave roller 33. When passage of the rear end of the first
original sheet is detected by the sensor position sensor 36 (Step
T14), a detection signal is output to the controller 40. The
controller 40 sends instruction signals to the lift mechanism 43 of
the press roller 29, third guide roller 39, extra roller 26 and
scanner 6 respectively.
[0146] When the second position sensor 36 detects passage of the
rear end of the first original sheet, the controller 40 causes the
third guide member 39 to pivot to the upper position F (Step T15)
and the extra roller 26 to rotate in the reverse direction
(counterclockwise in FIG. 15) (Step T16). The controller 40 then
lifts the press roller 29 so that the extra roller 26 contacts the
press roller 29 again (Step T17). From this point of time, the
angle sensor 48 measures the rotation angle of the giant feed
roller 28 (third rotation angle, greater than the second rotation
angle) which corresponds to the transportation distance of the
sheet rear end from the position of the second position sensor 36
to the front end of the platen glass 12, and the rotation angle of
the giant feed roller 28 (fourth rotation angle) which corresponds
to the transportation distance of the sheet rear end from the
position of the second position sensor 36 to a mid position between
the third guide member 39 and the nip of the extra roller 26 and
press roller 29. When the third rotation angle is arrived at (Step
T18), the scanning of the back side of the first original sheet is
completed (Step T19).
[0147] Further, when the fourth rotation angle is detected by the
angle sensor 48 (Step T20) and most of the first original sheet is
discharged from the paper exit 8b such that the rear end of the
sheet is only nipped between the extra roller 26 and press roller
29, then the third guide member 39 is caused to pivot to the lower
position E (Step T21), and the rotating direction of the extra
roller 26 is switched to the normal direction (clockwise in FIG.
15) (Step T22).
[0148] In this manner, the first original sheet is transferred and
caught by the giant feed roller 28 and first slave roller 31. As
shown in FIG. 20, the front end of the first original sheet (this
"front end" is the front end of the sheet when loaded at the paper
inlet 8a) is eventually detected by the second position sensor 36
(Step T23). A detection signal is issued to the controller 40. The
controller 40 issues command signals to the lift mechanism 43 of
the press roller 29 and the scanner 6.
[0149] As a result, the press roller 29 descends so that it is
separated from the press roller 29 (Step T24).
[0150] When the second position sensor 36 detects the front end of
the first original sheet, the controller 40 causes the angle sensor
48 to measure the rotation angle of the giant feed roller 28. When
the second rotation angle is arrived at (Step T25), the scanning of
the front side of the first original sheet is initiated (Step
T26).
[0151] Subsequently, the first original sheet is transported by the
giant feed roller 28 and second slave roller 32 or third slave
roller 33. When the second position sensor 36 detects passage of
the rear end of the first original sheet (Step T27), such a fact is
informed to the controller 40. The controller 40 issues command
signals to the second guide member 38, third guide member 39, extra
roller 26 and lift mechanism 43 of the press roller 29
respectively. After that, the controller 40 also issues command
signals to the scanner 6 and the power transmission mechanism 42 of
the drive unit 41.
[0152] The third guide member 39 pivots to the upper position F
(Step T28) and the second guide member 38 pivots to the lower
position C (Step T29). The extra roller 26 rotates in the reverse
direction (counterclockwise in FIG. 12) (Step T30) and the press
roller 29 ascends so that it contacts the extra roller 26 again
(Step T31).
[0153] As illustrated in FIG. 21, when the second position sensor
36 detects passage of the rear end of the first original sheet, the
controller 40 causes the angle sensor 48 to count the rotation
angle of the giant feed roller 28. When the third rotation angle is
reached (Step T32), the scanning operation applied to the front
side of the first original sheet is finished (Step T33).
[0154] The pick-up roller 21, separate roller 22, retard roller 23
and other rollers cooperate to separate the next uppermost sheet
(second original sheet) from the paper stack and feed it into the
paper path from the paper inlet 8a. The second original sheet is
fed into the second paper path R2' by the master feed roller 25 and
slave feed roller 24 (Step T34).
[0155] After the scanning of the front and back sides of the first
original sheet, the second original sheet is transported to the
paper exit 8b. When the first position sensor 35 detects passage of
the front end of the second original sheet (Step T35), a detection
signal is issued to the controller 40. The controller 40 then
issues a switching signal to the third guide member 39 such that
the third guide member 39 pivots to the lower position E (Step
T36). Of course, the first original sheet is already discharged
from the paper exit 8b by the extra roller 26 and press roller
29.
[0156] Regarding the subsequent treatment made to the second
original sheet, the program returns to Step T6 in FIG. 17, and
proceeds until Step T33 to transport and scan the original sheet.
Similar procedure will be taken for a next original sheet.
[0157] When the last original sheet is processed, there is no next
sheet so that the first position sensor 35 does not operate after
Step T33 in FIG. 21. After a predetermined period, the program is
terminated.
[0158] If the first position sensor 35 does not detect passage of a
sheet within a predetermined period, during which the angle sensor
48 counts the third rotation angle of the giant feed roller 28 at
Step T32 in FIG. 21 and a further angle larger than the fourth
rotation angle (Step T37), all the rollers are deactivated (Step
T38).
[0159] At this point of time, the last sheet is of course already
discharged from the paper exit 8b by the extra roller 26 and press
roller 29.
[0160] In this manner, the scanning to the first to last sheets is
complete.
[0161] If ADF 8 is sufficiently elongated in the forward and
backward directions (or the paper path is sufficiently elongated)
such that a front end of a larger sheet such as A3 size sheet does
not overlap a rear end of another larger sheet at the nip between
the rollers 26 and 29 when the sheet transportation direction is
reversed, then the lift mechanism 43 is not needed to the press
roller 29. Thus, the number of parts can be reduced and a
manufacturing cost is reduced. This can be said to both of the
embodiments described above.
[0162] In this configuration, Steps S23 and S36 are dispensed with
in the first embodiment, and Steps T11, T17, T24 and T31 are
dispensed with in the second embodiment.
[0163] Although the transportation distance of the sheet is
measured by the angle sensors 46 and 48 in the foregoing
embodiments, it may be measured by a stepper motor, which will be
installed in the drive power source 41. If a series of pulses are
applied to multiple phase windings of a fixed stator of the stepper
motor, a rotator rotates a predetermined angle upon each of the
pulses; the stepper motor rotates stepwise upon pulses. The
controller 40 counts the stepwise rotations of the stepper motor
and determines the moving distance of the sheet.
[0164] In the above described embodiments, the sheet is turned
upside down at the initial stage of the transportation process
prior to scanning, and transferred to the scanner 6. Accordingly,
the sheet passes over the platen glass 12 only twice. This reduces
the total time needed to scan both sides of the sheet. In addition,
the sheet placed at the feed tray 9 with its front side up is
scanned from its back side first. Then, the sheet is turned upside
down so that its front side is scanned. The sheet is then
discharged onto the discharge tray with its front side down. The
next sheet is discharged on the preceding sheet in the same manner.
Thus, page 1 (first sheet front side) is directed down, page 2
(first sheet back side) is directed up, page 3 (second sheet front
side) is directed down and contacts page 2, and page 4 (second
sheet back side) is directed up.
[0165] Since the sheet fed from the feed tray 9 is turned upside
down while it is moving in the second paper path R2', transported
backwards by the extra roller 26 and press roller 29, and guided by
the giant feed roller 28 and slave rollers 31, 32 and 33 to the
platen glass 12 (or the scanner 6), it does not approach the platen
glass 12 from the upper diagonal direction. This prevents slant
movement of the sheet so that the scanning degradation and jamming
are avoided.
* * * * *