Copying method and apparatus

In a document feeder, documents are contained on a document rest in a stacked state. These documents are sequentially transported to a specified exposure region on a table glass member of a copying machine by a feeder and transporter and are then exposed. The documents are then discharged again onto the document rest. The documents are thereby circulated for copying. When the documents are small in number, the documents are not discharged until a copying operation of a necessary number of sheets is completed, and the documents are moved back and forth for exposure between a transport path of the feeder and the transporter. This design enables the time required for copying a small number of documents to be shortened.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a copying method and apparatus using a 
recirculating document feeder, abbreviated as RDH, which enables exposure 
by sequentially taking out documents contained in a stacked state in means 
for containing. 
2. Description of the Related Art 
A copying machine is recently provided with a document feeder to feed 
documents sequentially to an exposure region in order to copy a plurality 
of sheet-like documents of a size efficiently. Also by repeating such 
copying operation a plurality of times, a plurality of sets of copies can 
be made arranged in the same order as documents. A typical prior art 
device for obtaining a plurality of copies is shown in U.S. Pat. No. 
3,499,710 in FIG. 1 and U.S. Pat. No. 4,179,215 in FIG. 2. 
FIG. 1 is a schematic sectional drawing of a document feeder 1 of the 
typical prior art. In the document feeder 1, document containers 4 and 5 
are situated on both sides of a exposure region 3 of a copying machine 
main body 2. These document containers 4 and 5 are constructed in the same 
manner, and in the state shown in FIG. 1. A plurality of documents 7 are 
stacked and contained in main body 6 of the document container 4 which is 
on document feeding side. The documents 7 are pressed toward a bottom 
plate 6a of the main body 6 by spring force of a spring member 8a from 
above via a pressing plate 8. In the vicinity of the bottom plate 6a of a 
main body 6, a discharge port 9 is formed directed to the exposure region 
3, and when a discharge roller 10 provided for the bottom plate 6 is 
driven, the documents in the bottommost layer are discharged through the 
discharge port 9. The documents 7 discharged through the discharge port 9 
are sent onto a platen 13 composing the exposure region 3 through means 
for guiding 11, and transported to a predetermined exposure position 
suitable for the size of the documents 7 by means for transporting 12 
realized by a transport belt or the like. 
After the image of the documents 7 is copied onto a copy sheet, the 
documents 7 are thrown into an input port 15 of an other document 
container 5 on document containing side from the transporting means 12 
through means for guiding 14. The input port 15 is formed above the level 
of the discharge port 9, and in the document container 5 on document 
containing side, the pressing plate 8 is displaced upward of the input 
port 15 against spring force of the spring member 8a by means for raising 
and lowering 16 realized by an electromagnetic plunger or the like. 
Accordingly, the documents taken out from the bottom side of the document 
container 4 are thrown into the input port 15 of the document container 5 
sequentially after exposure is made, therefore the documents 7 are 
contained in the document container 5 in the same order as when the 
documents were contained in the document container 4. When copying 
operation by the documents 7 in the document container 4 is all finished, 
the guiding means 11 connects the input port 15 of the document container 
4 and the transporting means 12, the guiding means 14 connects the 
discharge port 9 of the document container 5 and the transporting means 
12, further each pressing plate 8 in the document container 4 and 5 is 
raised and lowered respectively, and copying operation described above is 
made with the documents 7 from the document container 5. By moving the 
documents 7 back and forth in this way between the document container 4 
and the document container 5, a necessary number of copies can be made in 
the same order as the documents 7. 
On the other hand, the construction having the two document containers 4 
and 5 occupies a large installation space, therefore a recirculating 
document feeder 21 is put into practical use wherein a single document 
container 22 is provided as shown in FIG. 2 and the documents 7 taken out 
of the document container 22 are returned to the document container 22. In 
this recirculating document feeder 21, the documents 7 are taken out 
sequentially from the bottommost layer through a discharge port formed on 
a bottom plate 23a of a main body 23 of the document container 22 by a 
discharge roller 24, transported onto a platen 27 of a copying machine 
body 26 by means for transporting 25 and exposed, sent from the 
transporting means 25 via means for guiding 28, then thrown in from above 
the main body 23 of the document container 22. The documents 7 are thus 
sequentially taken out from the bottommost layer and exposed, then the 
documents 7 are stacked in the uppermost layer, and such operation is 
repeated to make a plurality of sets of copies in the same order as that 
of the documents. 
In the document feeding apparatus 1 constructed as described above, when 
copying of a few number of documents 7 is attempted in the same way as a 
large number of documents, feed of the documents for next copying 
operation can be restarted only after the documents are exposed and 
transported from the document container 4 on one side to the other side, 
i.e., the document container 5, then the guiding means 11 and 14 are 
driven to switch the discharge port 9 and the input port 15 as well as the 
raising and lowering means 16 is driven to vertically displace the 
pressing plate 8, which takes time. 
Also in the recirculating document feeder 21 in FIG. 2, when the documents 
7 are few, the guiding means 28 is sprung up as shown by a reference mark 
28a, and the documents 7 are contained temporarily in the transporting 
means 25 without the documents 7 being returned to the document container 
22. However, it still takes time since the length of a transporting path 
does not change much when the size of the documents 7 is small or the 
documents are small in number. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a copying method and 
apparatus using a document feeder which enables copying a small number of 
documents efficiently in a short time. 
The copying method according to the invention, in order to attain the 
object mentioned above, in a copying method using a document feeder 
comprises the steps of: 
containing documents in a container in a stacked state in a predetermined 
order; 
supplying documents stacked in the container from one of an uppermost layer 
or a bottommost layer sequentially one by one and transporting the 
documents to an exposure region; 
discharging documents after exposure from the exposure region to the other 
of the uppermost layer or the bottommost layer and stacking the documents 
in the predetermined order; and 
controlling the steps of supplying and discharging interlocked with copying 
operation; 
wherein the documents are taken out, exposed, and discharged in a 
circulating manner to enable copying of a plurality of documents in the 
predetermined order, 
the method further comprising the step of detecting the length of the 
documents at least in transport direction, wherein during the step of 
controlling means, in response to a detection result during the step of 
detecting, when the sum of length of documents to be copied in the 
transport direction is below a predetermined length, the documents are 
moved back and forth in a transport path for repeating copying without 
discharging the documents to be copied. 
Also the copying method according to the invention, in a copying method 
using a document feeder provided with an invertor which inverts the faces 
of a copy sheet to enable copying on both faces of the copy sheet 
comprises the steps of: 
containing documents in a container in a stacked state in a predetermined 
order; 
supplying documents stacked in the containing from one of an uppermost 
layer or a bottommost layer sequentially one by one and transporting the 
documents to an exposure region; 
discharging documents after exposure from the exposure region to the other 
of the uppermost layer or the bottommost layer and stacking the documents 
in the predetermined order; and 
controlling the steps of supplying and discharging interlocked with copying 
operation; 
wherein the documents are taken out, exposed, and discharged in a 
circulating manner to enable copying of a plurality of documents in the 
predetermined order. 
the method further comprising the step of detecting the length of the 
documents at least in transport direction, wherein during the step of 
controlling, in response to a detection result during the step of 
detecting, when the sum of length of documents to be copied in the 
transport direction is below a predetermined length, the documents are 
moved back and forth in a transport path for repeating copying without 
discharging the documents to be copied and inverting of the documents is 
allowed for copying on both faces of the copy sheet. 
Further the copying apparatus according to the invention, in a copying 
apparatus using a document feeder comprising: 
means for containing documents in a stacked state in a predetermined order; 
means for supplying which takes out documents stacked in the containing 
means from one of an uppermost layer or a bottommost layer sequentially 
one by one and transports them to an exposure region; 
means for discharging which discharges documents after exposure from the 
exposure region to the other of the uppermost layer or the bottommost 
layer and stacks them in the predetermined order; and 
means for controlling the supplying means and the discharging means 
interlocked with copying operation; 
wherein the documents are taken out, exposed, and discharged in a 
circulating manner to enable copying of a plurality of documents in the 
predetermined order, 
the copying apparatus further comprises means for detecting the length of 
the documents at least in transport direction, wherein the controlling 
means, in response to a detection result by the means for detecting, when 
the sum of length of documents to be copied in the transport direction is 
below a predetermined length, moves the documents back and forth in a 
transport path for repeating copying without discharging the documents to 
be copied. 
Also the copying apparatus according to the invention, in a copying 
apparatus using a document feeder comprising: 
means for inverting which inverts faces of a copy sheet to enable copying 
on both faces of the copy sheet; 
means for containing documents in a stacked state in a predetermined order; 
means for supplying which takes out documents stacked in the containing 
means from one of an uppermost layer or a bottommost layer sequentially 
one by one and transports them to an exposure region; 
means for discharging which discharges documents after exposure from the 
exposure region to the other of the uppermost layer or the bottommost 
layer and stacks them in the predetermined order; and 
means for controlling the supplying means and the discharging means 
interlocked with copying operation; 
wherein the documents are taken out, exposed, and discharged in a 
circulating manner to enable copying of a plurality of documents in the 
predetermined order, 
the copying apparatus further comprises means for detecting the length of 
the documents at least in transport direction, wherein the controlling 
means, in response to a detection result by the means for detecting, when 
the sum of length of documents to be copied in the transport direction is 
below a predetermined length, moves the documents back and forth in a 
transport path for repeating copying without discharging the documents to 
be copied as well as operates the inverting means to allow copying on both 
faces of the copy sheet. 
A preferable embodiment is characterized in that means for counting is 
provided relating to the controlling means, which counts the number of 
times of the back-and-forth movement, wherein the controlling means allows 
the documents to be discharged once, then taken in to continue copying 
operation when the number of times of the back-and-forth movement counted 
by the counting means is above a predetermined number. 
Another preferable embodiment is characterized in that the detecting means 
comprises a sheet detector provided for the containing means to detect a 
document size and a document detector provided for the feeding means to 
detect presence of documents, wherein the controlling means multiplies the 
length of a document detected by the sheet detector and the number of 
documents detected by the sheet detector and the document detector to 
obtain the sum of lengths in the transporting direction. 
According to the invention, in a copying apparatus using a recirculating 
document feeder which takes out documents contained in the containing 
means in a stacked state in a predetermined order sequentially one by one 
from one of the uppermost layer or the bottommost layer by use of the 
feeding means and transports them to an exposure region, and discharges 
the documents after exposure to the other of the uppermost layer or the 
bottommost layer of the documents in the containing means by use of the 
discharging means thereby enabling copying of a plurality of documents in 
the predetermined order, means for detecting is provided to detect the 
length of the documents at least in a transport direction. Further the 
controlling means to control taking out, exposure, and discharge of the 
documents, in response to a detection result of the detecting means, when 
the sum of length of documents to be copied in the transport direction is 
below a predetermined length, e.g., the length of a transport path to feed 
the documents taken out of the containing means to the exposure region, 
therefore when the number of documents to be copied is relatively small, 
allows the documents to be copied to move back and forth in the transport 
path to repeat copying operation without discharging the documents to be 
copied. 
Accordingly, the length of a transport path of documents can be drastically 
shortened compared to the case where the documents are once discharged to 
the containing means and taken in again for exposure, thereby shortening 
time required for copying operation. 
Also according to the invention, in a copying apparatus using a 
recirculating document feeder described above, means for inverting the 
faces of a copy sheet is provided, whereby when copying a so-called 
simplex document the record of which on its single face is to be copied 
onto both faces of a copy sheet, in the case where the sum of length of 
documents in a transport direction is below a predetermined length, e.g., 
1/2 of an exposure region, the documents to be copied are moved back and 
forth in a transport path without being discharged as well as the 
inverting means is operated interlocked with the back-and-forth movement, 
thereby enabling, e.g., copying on both faces from two simplex documents. 
Therefore, in copying the first document on one face of copy sheets 
successively and accumulating them once in a so-called intermediate tray 
then copying the second document on the other face of the copy sheets, 
copying operation is allowed to be continued as long as copy sheets can be 
fed irrespective of the number of sheets that can be contained in the 
intermediate tray. 
Also preferably, the number of times of the back-and-forth movement is 
counted by a counter, and when the count is above a predetermined number, 
documents are once discharged and taken in again to allow copying 
operation to continue, which enables clearance of discrepancy due to 
repeat back-and-forth movement for every predetermined number of times 
mentioned above, thereby improving quality of copy. 
Further preferably, the detecting means comprises a sheet detector provided 
for the containing means to detect a document size and a document detector 
provided for the feeding means to detect presence of documents, wherein 
the length of a document detected by the sheet detector and the number of 
documents detected by the sheet detector and the document detector are 
multiplied to obtain the sum of lengths in the transport direction. 
Further scope of applicability of the present invention will become 
apparent from the detailed description given hereinafter. However, it 
should be understood that the detailed description and specific examples, 
while indicating preferred embodiments of the invention, are given by way 
of illustration only, since various changes and modifications within the 
spirit and scope of the invention will become apparent to those skilled in 
the art from this detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Now referring to the drawing, preferred embodiments of the invention are 
described below. 
FIG. 3 is a sectional view of a recirculating document feeder 31 as a first 
embodiment of the invention, and FIG. 4 is a sectional view showing a 
construction of a transfer type electrostatic copying machine 100 equipped 
with the document feeder 31. The document feeder 31 comprises in general a 
document rest 32, means for feeding 33, means for transporting 34, and 
means for discharging 35. 
The document rest 32 is composed with a side regulating plate 42 provided 
for a concave position 41 in a casing 40. One or plurality of documents 43 
are contained in a stacked state on the document rest 32, and both ends in 
the width direction of the documents 43, i.e., the direction perpendicular 
to the sheet face in FIG. 3 are aligned by the side regulating plate 42. 
The size of the documents 43 placed on the document rest 32 is detected by 
sheet detectors Sa, Sb, and Sc. On the side of the feeding means 33 of the 
document rest 32, means for sending 44 is provided composed of a round 
endless belt B1 wound between a pair of rollers R1a and R1b. 
Of the documents 43, sent from the sending means 44 of the document rest 
32, with their tip 43a facing an intake 51 of the feeding means 33, the 
tip 43a is blown by air from an air duct 52, and only the first document 
43x in the bottommost layer is sent to the feeding means 33 by the sending 
means 44. 
The feeding means 33 comprises a cylindrical feeding roller 53 to transport 
the documents 43 inserted through the intake 51, a guiding member 54 
externally surrounding the feeding roller 53 with a slight clearance left, 
a plurality of follower rollers 55 pressed to the peripheral surface of 
the feeding roller 53 to transport the documents 43 without slipping, and 
an inverting member 56 to invert the faces of the documents 43 as 
described below. The documents inserted through the intake 51, via a 
transport path 60 formed on the peripheral face of the feeding roller 53, 
are sent to the transporting means 34 situated above table glass 57 of the 
copying machine 100. 
When the documents 43 are so-called duplex documents with an original image 
formed on both faces of the documents 43, the documents 43 returned from 
the transporting means 34 are introduced to the inverting path 59 with the 
feeding roller 53 inverted as well as the inverting member 56 displaced in 
the direction of an arrow 58, and the documents 43 are sent again onto the 
table glass 57 with their faces inverted. Document detectors Sd, Se, and 
Sf are situated on the transport path 60 and inverting path 59 in order to 
detect paper clogging or the like. 
The transporting means 34 comprises a pair of rollers R2a and R2b, an 
endless belt B2 wound around between the rollers R2a and R2b facing the 
table glass 57 and a plurality of press roller R3 and R4 pressing the belt 
B2 to the table glass 57. The press roller R3 facing the feeding means 33 
is displaced to and off the table glass 57 by an electromagnetic solenoid 
or the like. 
For the main body 99 of the copying machine 100, a stop piece 61 is 
provided at the end on the side of the feeding means 33 of the table glass 
57. The stop piece 61 is supported with its supporting point 61a free to 
swivel, and its idle end 61b is vertically displaced by an electromagnetic 
solenoid or the like in correspondence to detaching and attaching 
displacement of the press roller R3. 
When the documents 43 are sent in from the feeding means 33, the press 
roller R3 is detached off the table glass 57 and the idle end 61b of the 
stop piece 61 is lowered, whereby the documents 43 are smoothly taken into 
the transporting means 34 and transported in the direction of an arrow 62 
by the belt B2. When the documents 43 are securely taken into the 
transporting means 34, the press roller R3 is attachingly displaced to the 
table glass 57 as well as the stop piece 61 is raised. At this time, the 
rollers R2a and R2b are slightly inverted, and the rear end 43b of the 
documents 43 comes into contact with a stage difference face formed by the 
idle end 61b of the stop piece 61, thereby positioning the documents 43. 
Then the documents 43 are exposed and copied as described below. When the 
copying operation is completed, the documents 43 are transported in the 
direction of the arrow 62 and taken into the discharging means 35. 
The discharging means comprises a cylindrical discharge roller 63, a 
guiding member 64 externally surrounding the discharge roller 63 leaving a 
slight clearance, and a plurality of follower rollers 65 pressed to the 
peripheral surface of the discharge roller 63. The documents 43 sent into 
the discharging means 35 are transported by the discharge roller 63, 
discharged onto the document rest 32 through a discharge port 67 via a 
transport path 66 comprising the discharge roller 63 and the guiding 
member 64, and placed on the uppermost layer of the stacked documents 43. 
In this way, the documents 43 stacked on the document rest 32 are 
sequentially taken in, thereby enabling an efficient copying operation. 
FIG. 5 is a block diagram showing an electric construction of the document 
feeder 31 constructed as described above. A detection result from the 
sheet detectors Sa, Sb, and Sc located at the document rest 32 and the 
document detectors Sd, Se, and Sf located at the feeding means are input 
to the processing circuit 72 including a microcomputer through an input 
interface circuit 71. Also, when a copying operation is started, a 
detection result by a circulation detector Sg facing the uppermost layer 
of the stacked documents 43 including a so-called micro switch is input to 
the processing circuit 72 via the input interface circuit 71. The 
circulation detector Sg, by detecting that a document which was on the 
uppermost layer when copying operation was started is taken into the 
feeding means 33, detects that the documents 43 to be copied have 
circulated. 
The processing circuit 72 feeds the documents 43 onto the table glass 57 in 
accordance with a document feeding procedure stored in a Read Only Memory 
(abbreviated as ROM) 73, and realizes copying operation interlocked with 
the main body 99 via an I/O interface circuit 74. The processing circuit 
72 stores a detection result by the detectors Sa, Sb, and Sc or the like 
in a Random Access Memory (abbreviated as RAM) 75 as well as performs a 
counting operation to check whether the number of the documents 43 has 
reached a specified number by means of the RAM 75. 
Control outputs from the processing circuit 72 are output to a motor drive 
circuit 77, a solenoid drive circuit 78, and a clutch drive circuit 79 
through an output interface circuit 76. The motor drive circuit 77 
controls a motor to drive the rollers 53, 63, R1a, and R2a. The solenoid 
drive circuit 78 drives an electromagnetic solenoid to drivingly displace 
the inverting member 56 and the press roller R3. Also the clutch 79 
intervenes between the rollers 53, 63, R1a, and R2a and the motor and 
conducts or interrupts a motor drive force to the rollers 53, 63, R1a, and 
R2a instantaneously in response to an output from the processing circuit 
72. Further the processing circuit 72 drivingly controls the 
electromagnetic solenoid to raise and lower the stop piece 61 on the main 
body 99 side through the I/O interface circuit 74. 
The document feeder 31 constructed as described above, when there are a 
relatively large number of documents 43 and when the size thereof is 
relatively large, takes out the documents 43 sequentially from the 
document rest 32 for exposure, then discharges onto the document rest 32 
again. In this case, when the first document 43x is completely taken into 
the transporting means 34 from the feeding means 33 and positioned by the 
stop piece 61 or the like, the next document 43y is taken in by the 
feeding means 33, and stands by at the exit of the transport path 60 while 
the first document 43x is being exposed. Accordingly, when exposure of the 
first document 43x is completed and discharge from the feeding means 34 is 
started, the next document 43y is sent into the transporting means 34, 
thereby saving time for successive copying operation of the documents 43. 
On the other hand, when the documents 43 are relatively small and few, 
relating to the documents 43 placed on the document rest 32 as shown in 
FIG. 6(A), the first document 43x in the bottommost layer is first taken 
into the feeding means 33 as shown in FIG. 6(B), further the first 
document 43x is sent into the transporting means 34 on the table glass 57 
and positioned by the press roller R3 and the stop piece 61, meanwhile the 
second document 43y, that is a document in the uppermost layer placed on 
the document rest 32 since the number of the documents 43 is assumed to be 
two in the embodiment, is taken into the feeding means 33, thereby a 
so-called preparatory sheet feed is started. 
Then, as shown in FIG. 6(D), while the first document 43x positioned in a 
specified exposure region W1 is being exposed, the second document 43y 
already stands by near the end of the transport path 60 of the feeding 
means 33, thus the preparatory sheet feed is completed. When exposure of 
the first document 43x is completed, the document 43x is temporarily 
transported in the direction of the arrow 62 as shown in FIG. 6(E), and 
discharged out of the exposure region W1. The second document 43y is then 
positioned on the exposure region W1. 
When exposure of the second document 43y is thus completed, the 
transporting means 34 and the feeding means 33 are inverted, and the 
second document 43y is taken in the feeding means 33 again as shown in 
FIG. 6(D) as well as the first document 43x is positioned by the stop 
piece 61 to be charged in the exposure region W1. Then, when exposure of 
the first document 43x is completed, the second document 43y is charged in 
the exposure region W1 again as shown in FIG. 6(E), and when the operation 
shown by FIG. 6(D) and FIG. 6(E) is repeated for a desired number of 
copies, the documents 43x and 43y after exposure are sequentially 
discharged onto the document rest 32 from the discharging means 35 as 
shown in FIG. 6(F) and FIG. 6(G). 
FIGS. 7(A) and 7(B) are charts showing a copying operation of a small 
number of documents shown in FIG. 6. In Step n1, the size of the documents 
43 placed on the document rest 32 is detected by the sheet detectors Sa, 
Sb, and Sc, and stored in the RAM 75. In Step n2, an electromagnetic 
clutch and a motor for driving the rollers R1a and 53 are driven via the 
motor drive circuit 77 and the clutch drive circuit 79 to start sheet 
feeding. 
The motor for driving the rollers R1a, R2a, 53, and 63 is equipped with a 
pulse generator, and counting pulses from the pulse generator enables 
detecting rotating amount of the rollers R1a, R2a, 53, and 63, i.e., 
transport amount of the documents 43. 
Therefore, in Step n3, the pulses from a pulse generator installed on the 
motor for driving the rollers R2a and 53 started to be driven in the Step 
n2 are counted. In Step n4, it is determined whether the number of pulses 
counted in the Step n3 has reached a predetermined pulse count, i.e., a 
specified pulse count which is a pulse count corresponding to transport 
amount required for charging a document of a size detected in the Step n1 
to the exposure region W1 plus a slight pulse count, and when it has not, 
control returns to Step n3 to continue transport operation, and when the 
number of pulses reaches the specified pulse count, control moves to Step 
n5. 
In Step n5, the stop piece 61 is raised as well as the roller R2a is 
inverted for the slight pulse count, and the end 43b of the first document 
43x comes into contact with the stop piece 61, whereby a charge in the 
specified exposure region W1 is completed. In step n6, a transport of the 
second document 43y, i.e., a preparatory sheet feed is started. In Step 
n7, transport amount of the document 43y, i.e., a pulse number of the feed 
roller 53 is counted, in Step n8, it is determined whether the pulse count 
has reached a specified pulse count corresponding to a specified standby 
position of the document 43y, and in the case where it has not, control 
returns to the Step n7, and when a preparatory sheet feed up to a 
specified standby position is completed, control moves to Step n9. In Step 
n9, a copying operation of the first document 43x is performed on the main 
body 99 side described later. 
When a copying operation of the first document 43x is thus completed, then 
a transport of the document 43x in the direction of the arrow 62 is 
started in Step n11. In Step n12, the pulses from the pulse generator of 
the motor to drive the roller R2a are counted, and it is determined 
whether a specified pulse count is reached or not in Step n13, and if it 
is not, control returns to the Step n12, and when the predetermined pulse 
count is counted, control moves to Step n14. It enables a spacing to be 
kept between the first document 43x and the second document 43y 
corresponding to the predetermined pulse count. 
In Step n14, the feeding roller 53 as well as the roller R2a is driven, 
thereby transporting both the documents 43x and 43y in the arrow 62 
direction. In Step n15, the pulses from the pulse generator corresponding 
to the rollers R2a and 53 are counted. In Step n16, it is determined 
whether the count has reached a specified pulse count corresponding to a 
transport amount for the second document 43y lying in the standby position 
to move a predetermined slight distance along the exposure region W1, and 
in the case where it has not, control returns to the Step n15, and when 
the specified pulse count is counted control moves to Step n17. In Step 
n17, the roller R2a is inverted for a predetermined slight count of 
pulses, the document 43y is charged in the exposure region W1, and a 
copying operation is performed in Step n18. In Step n21, it is determined 
whether a copying operation of a preset number of copies is completed, and 
in the case where it is, control moves to Step n22, the rollers R2a and 63 
are driven, and both the documents 43x and 43y are transported in the 
arrow 62 direction and discharged, thereby the operation is completed. 
On the other hand, in the Step n21, when a copying operation of a preset 
number of copies is not completed, control moves to Step n23, the rollers 
R2a, 53, and 63 are driven in the opposite direction, and the documents 
43x and 43y are both transported opposite the arrow 62 direction. In Step 
n24, the pulses from the pulse generator corresponding to the roller R2a 
are counted. In Step n25, it is determined whether a pulse count is 
counted corresponding to an amount of the inverted transport to the 
exposure region W1 of the first document 43x, and in the case where it is 
not, control returns to Step n24, and when the inverted transport to the 
specified exposure region W1 is completed, control moves to Step n26. 
As for this Step n26 and after, in the same way as in the Steps n9 through 
n16, when a copying operation of the first document 43x is performed in 
Step n26, both the documents 43x and 43y are transported in the arrow 62 
direction in step n27, when a count corresponding to a transport amount 
counted in Step n28 reaches a specified pulse count in Step 29, the 
document 43y is inversely transported for the slight distance in Step n30 
and positioned, and when a copying operation of the document 43y is 
performed in Step n31, control returns to the Step n21. When a copying 
operation of a specified number of copies is completed by repeating Steps 
n23 through n31, control moves to the Step n22 and the documents 43x and 
43y are discharged, then the copying operation is completed. 
As is shown, in the document feeder 31 according to the invention, when the 
number of the documents 43 is small, the documents 43 are moved back and 
forth on the transport path consisting of the feeding means 33, the 
transporting means 34, and the discharging means 35 without being 
discharged onto the document rest 32, thereby allowing a copying operation 
in the order of stack, which results in a remarkably shortened time 
required for copying operation compared to the case where the documents 43 
whose copying operation is over are once discharged to the document rest 
32. 
Whether the number of the documents 43 is small or not is determined 
depending on whether the rear end 43b of the last document 43y is taken in 
the feeding means 33 when the stacked documents 43 are sequentially taken 
in and the first document 43x faces the exposure region W1. Therefore, at 
the point when the last document 43y is taken out of the document rest 32, 
the processing circuit 72 multiplies the size and the number of the 
documents 43 to obtain the sum of lengths in a transport direction, and 
when the sum is below a predetermined length L1, it is determined that the 
number of the documents 43 is small. 
More specifically, when the maximum number of the documents allowing 
copying operation described above is made N, it is provided by the 
following equation where the length in a transport direction of the 
documents 43 is made L2: 
EQU N=(L1/L2)+1, where N is an integer. 
The predetermined length L1 may be set either corresponding to the length 
of the transport path 60 in the feeding means 33 or using the length of 
the inverting path 59 as shown by a reference mark L1 in FIG. 6(G). Also 
the documents 43 from the discharge roller 63 are not circulated to the 
document rest 32 via the transport path 66, but may be circulated to the 
upper face of the belt B2 opposite the face facing the table glass 57, 
thereby increasing the maximum number N. 
FIGS. 8(A) and 8(B) are flow charts showing an operation of another 
embodiment of the invention, where the embodiment is similar to the 
embodiment described above and the same reference numerals are attached to 
the corresponding parts. It should be noted in this embodiment that when a 
copying operation by moving the documents 43x and 43y back and forth in 
the exposure region W1 as shown in the FIG. 6(D) and FIG. 6(E) is 
performed a predetermined number of times, the documents 43x and 43y are 
once discharged as shown in the FIG. 6(F) and FIG. 6(G), then taken in 
again as shown in FIG. 6(A) through FIG. 6(D), which means that the 
documents 43x and 43y are once circulated to continue a copying operation. 
More specifically, when a copying operation of a preset number of copies is 
not completed in the Step n21, control moves to Step n41, where the number 
of times of back-and-forth movement of the documents 43x and 43y on the 
exposure region W1 is counted. In Step n42, it is determined whether the 
number of times is above a predetermined one, and in the case where it is 
not, control moves to the Step n23 and after, and a copying operation by 
moving the documents 43x and 43y back and forth is continued, while in the 
case where it is, control moves to Step n43, and the count of times of the 
back-and-forth movement is reset, then the rollers R2a and 63 are driven 
to transport the documents 43x and 43y both in the arrow 62 direction and 
once discharged in step n44, then control returns to the Step n2 where a 
sheet feeding operation is restarted. 
Thereby a so-called center misalignment of the documents 43x and 43y in the 
perpendicular direction for the transport direction shown by the arrow 62 
and a rotational displacement named skew due to static electricity and 
displacement caused in transporting by the belt B2 are cleared by once 
circulating the documents 43x and 43y, and a copy quality is maintained in 
a desired allowable range as well as time required for copying operation 
reduced. 
Referring to FIG. 4 again, facing the documents 43 placed on the exposure 
region W1 of the table glass 57 in the copying machine main body 99, 
provided is means for exposing 149. The exposing means 149 comprises a 
light source 150 to expose the documents 43 through a slit, reflecting 
mirrors 151a, 151b, 151c, and 151d, and a zooming lens 152. When the light 
from the light source 150 is radiated on the document image of the 
documents 43, the reflected light is focused on an exposure region 130 of 
a photosensitive member 101 via the reflecting mirrors 151a through 151d 
and the zooming lens 152. In the exposing means 149, a first moving body 
98 equipped with the light source 150 and the reflecting mirror 151a, 
corresponding to the size of the documents 43, performs exposing and 
reading while scanning a reading position along the table glass 57. Such 
an exposing and reading operation is performed as the exposing means 149 
is driven by a drive motor M13. 
The photosensitive member 101 is drivingly rotated in the arrow 97 
direction as well as charged by a charging corona discharger 102. The 
charged photosensitive member 101 is focused on the reflected light via 
the exposing means 149 in the exposing region 130, whereby an 
electrostatic latent image is formed corresponding to a read document 
image. The electrostatic latent image is formed into a toner image by a 
developing apparatus 103. The toner image is transferred by a transferring 
corona discharger 131 onto copy sheets P fed to the photosensitive member 
101 as described below in a transfer region 129. The copy sheets P after 
transfer are transported to a fixing apparatus 104 by means for 
transporting 132, where fixing is performed. 
When transfer is completed in the transfer region 129, toner remaining on 
the photosensitive member 101 is removed by a cleaning apparatus 133 
placed downstream of the transfer region 129 in the rotating direction. 
Then a remaining electric charge on the photosensitive member 101 is 
removed by a dielectrifying apparatus 134, and after that, the surface of 
the photosensitive member 101 is charged by the charging corona discharger 
102 in order to form an electrostatic latent image again. 
On one side in the copying machine main body 99 sheet feed cassettes 106a 
and 106b are installed which contains the copy sheets P, and in the lower 
part of the main body 99, sheet feed cassettes 106c and 106d are 
installed. The copy sheets P contained in these sheet feed cassettes 106a 
through 106d in a stacked state are taken out sequentially one by one from 
the uppermost layer, and fed to sheet feed paths 108a through 108d 
respectively. The feed operation is achieved because sheet feed rollers 
109a through 109d placed on the upper face of the sheet feed cassettes 
106a through 106d are drivingly rotated by a sheet feed drive motor M8. On 
the sheet feed paths 108a through 108d and on a sheet feed path 115 from 
an intermediate tray 113 described below, sheet transport rollers 107a 
through 107e are placed respectively, and these transport rollers 107a 
through 107e are drivingly rotated by a drive motor M9, thereby feeding 
copy sheets P to a copy process part of the photosensitive member 101 or 
the like. 
The copy sheets P transported from the sheet feed cassettes 106a through 
106d and the intermediate tray 113 are controlled by registration rollers 
160a and 160b installed on a transport path to the photosensitive member 
101 in a timing of transport to the photosensitive member 101. More 
specifically, when the tip of copy sheets P in a transport direction 
transported to the photosensitive member 101 reaches between the 
registration rollers 160a and 160b, a transport of the copy sheets P is 
once stopped, and when the documents 43 are charged in the exposure region 
W1 by the document feeder 31, copy sheets P are fed interlocked with the 
exposing means 149 and the photosensitive member 101. Such a rotation/stop 
control of the registration rollers 160a and 160b is applied by an on/off 
control of a clutch intervening with a drive motor. 
On the other side of the copying machine 99, a discharge tray 110 is 
located. The discharge tray 110 is equipped with a solenoid SOL8, and when 
the solenoid SOL8 is energized for a specified time, the discharge tray 
110 is displaced to the near side of the paper of FIG. 4, and when the 
solenoid SOL8 is energized for a specified time next, it is displaced to 
the back side of the paper. It enables an operator to take out the copy 
sheets P provided in a plurality of pieces for a plurality of documents in 
an assorted state. 
Correspondingly in the main body 99 provided are a discharge path 111 for 
discharging the copy sheets P which have passed through the fixing 
apparatus 104 from the copying process to the discharge tray 110 and an 
inverting path 112 branched from the discharge path 111. The copy sheets 
P, passing through the fixing apparatus 104 from the copying process, on 
whose one surface copying is made corresponding to a document image, are 
discharged to the discharge tray 110 in the three types of modes 1-3 below 
according to copy contents desired by the operator. 
1. The copy sheets P, passing the discharge path 111 as they are, are 
discharged to the discharge tray 110. 
2. The copy sheets P, heading for the discharge path 111, are inversely 
transported by the inverting path 112 for copying to be performed on the 
other surface thereof, then temporarily contained in the intermediate tray 
113 in order to be transported to the copying process again. The copy 
sheets P stacked in the intermediate tray 113 are fed, sequentially from 
the bottommost layer, to the copying process via the transport path 115 by 
the feeding means 114 drivingly rotated by a motor M14, and discharged to 
the discharge tray 110 via the discharge path 111 from the fixing 
apparatus 104. 
3. The copy sheets P, once heading for the discharge path 111, are inverted 
upside down by the inverting path 112, then discharged to the discharge 
tray 110. 
The inverting path 112, in order to enable such a transport operation of 
the copy sheets P, comprises paths 112a and 112b branched from two 
positions on the discharge path 111, a path 112c where the paths 112a and 
112b join together, and a path 112d heading for the intermediate tray 113 
branched from the path 112c. A first direction changing claw 115 is 
situated in a portion where the path 112a is branched from the discharge 
path 111, a second direction changing claw 116 in a portion where the path 
112a and the path 112b join together, and a third direction changing claw 
117 in a portion where the path 112c and 112d are branched, in a 
respective manner. These first to third direction changing claws 115 
through 117 are actuated respectively by solenoids not shown, by which a 
transport path of copy sheets P is chosen as described above according to 
copying contents desired by the operator. 
Rollers 118a, 118b, and 118c are situated in the vicinity of a portion 
joining the path 112a and the path 112b, and rollers 119a, 119b, and 119c 
in the vicinity of a portion branching the path 112c and the path 112d, 
serving respectively to transport the copy sheets P. Also, inverting 
rollers 120 are situated along the path 112c in the vicinity of a portion 
joining the path 112a and the path 112b, and drivingly rotated normally 
and inversely by a drive motor not shown to invert a transport direction 
of the copy sheets P. An inverting roller 121 is situated downward of the 
branch portion of the path 112c and the path 112d, and drivingly rotated 
normally and inversely by the drive motor not shown. Further, a discharge 
detector S13 is situated in the vicinity of the outlet of the discharge 
path 111, copy sheet inversion detectors S14 and S15 in the vicinity of 
the outlet of the path 112a and along the path 112c, and also an 
intermediate tray inlet detector S16 in the vicinity of the outlet of the 
path 112d in a respective manner. 
According to a construction of the inverting path 112 described above, in 
the discharge mode 1, the path 112a is closed against the discharge path 
111 by the first direction changing claw 115, thereby discharging the copy 
sheets P along the discharge path 111. Also, in the discharge mode 2, the 
discharge path 111 is closed by the first direction changing claw 115 to 
introduce the copy sheets P to the path 112a, and the path 112c is opened 
by the second direction changing claw 116, and a transport direction is 
inverted by the inverting roller 121 on the path 112c. Then, the path 112d 
is opened by the third direction changing claw 117, thereby discharging 
the copy sheets P to the intermediate tray 113. Further, in the discharge 
mode 3, the copy sheets P are introduced to the path 112c as described 
above, then a transport direction is inverted by the inverting roller 120, 
and the path 112a is closed by the second direction changing claw 116 as 
well as the path 112b is opened, thereby leading the copy sheets P to the 
discharge path 111 from the path 112b. 
The copying machine 100 is provided with a sheet feed detector S10 to 
detect a sheet feed from the sheet feed cassettes 106a through 106d, a 
pre-transference copy sheet detector S11, a post-fixation detector S12, an 
intermediate tray sheet detector S17, and an intermediate tray sheet feed 
detector S18 or the like in order to detect a state of a transport of the 
copy sheets P from the sheet feed cassettes 106a through 106d. 
The copying machine 100 according to the invention provided with the 
recirculating document feeder 31 and having a construction for duplex 
copying including the inverting path 112 and the intermediate tray 113 
achieves copying contents desired by the operator unrestrictedly, in both 
simplex and duplex copying from simplex or duplex documents with the copy 
sheets P assorted, by circulating the documents 43 and copy sheets P a 
plurality of times. 
Accordingly, especially when the documents 43 are so-called simplex 
documents whose contents recorded on one surface only are to be copied, in 
a so-called page-to-page copying mode to copy two sheets of the documents 
43 respectively onto both surfaces of the copy sheets P, the invention can 
be embodied in a preferred manner as described below. FIGS. 9(A)-9(G) are 
sectional view showing an operation of another further embodiment of the 
invention. When the size of the documents 43 is relatively large, the 
documents 43 are taken sequentially out of the document rest 32, exposed 
in a specified preset number or in a number containable in the 
intermediate tray 113, then discharged to the document rest 32. At this 
time, when positioning of the first document 43x is completed as described 
above, a preparatory feed of the next document 43y is performed as 
described above. 
On the other hand, when the size of the documents 43 is relatively small, 
for example when the length L2 of the documents 43 in the transport 
direction is below 1/2 of the length W2 of the table glass 57 which is the 
maximum of the exposure region W1 (illustrated in FIG. 9(D), a duplex 
copying operation is performed as follows: 
Of the documents 43 placed on the document rest 32 shown in FIG. 9(A), the 
preceding first document 43x in the bottommost layer is first taken in the 
feeding means 33 as shown in FIG. 9(B). Further, as shown in FIG. 9(C), 
when the first document 43x is sent to the transporting means 34 on the 
table glass 57 and is positioned by the pressroller R3 and the stop piece 
61, the following second document 43y is already taken in the feeding 
means 33, whereby a preparatory sheet feed is started. 
Then as shown in FIG. 9(D), while the first document 43x positioned in the 
exposure region W1 is being exposed, the second document 43y stands by 
near the end of the transport path 60, whereby a preparatory sheet feed is 
completed. When an exposure of the first document 43x is completed for the 
preset number of sheets or the number of sheets containable in the 
intermediate tray 113, the document 43x is temporarily transported in the 
arrow 62 direction as shown in FIG. 9(E), and discharged out of the 
exposure region W1 corresponding to the size of the documents 43 on the 
table glass 57 as well as the second document 43y is positioned in the 
exposure region W1. 
When an exposure of the second document 43y is thus completed for the 
preset number of sheets or the number of sheets containable in the 
intermediate tray 113, the second document 43y is taken in the feeding 
means 33 again as well as the first document 43x is positioned by the stop 
piece 61 and set in the exposure region W1 as shown in the FIG. 9(D). 
Then, when the exposure of the first document 43x is completed, the second 
document 43y is set again in the exposure region W1 as shown in FIG. 9(E). 
When such an operation as shown in FIG. 9(D) and FIG. 9(E) is repeated for 
a preset number of sheets, the documents 43x and 43y after exposure are 
sequentially discharged onto the document rest 32 as well as the next set 
of documents 43xa and 43ya for duplex copying are taken in and set in the 
exposure region W1 as shown in FIG. 9(F) through FIG. 9(G). In the case 
where the preset number of sheets is larger than that of sheets 
containable in the intermediate tray 113, when an exposure of the final 
document is completed, the first document 43x is first taken in again, and 
copying is performed up to a preset number of sheets. 
FIGS. 10(A) and 10(B) are flow charts showing the operation shown in the 
FIGS. 9(A)-9(G) when a size of documents is small. This embodiment is 
similar to one described above, and the same reference numerals are 
attached to the corresponding parts. The number of the documents 43 is 
assumed to be two in order to simplify a description. When the copying 
operation of the first document 43x is completed in the Steps n1 through 
n9, control moves to Step n51, it is determined whether a copying 
operation onto the copy sheets P is completed for a preset number, and in 
the case where it is not, it is determined whether the count of copying 
operations has reached the number of sheets containable in the 
intermediate tray 113 in Step 52, and in the case where it has not, 
control returns to the Step n9 and copying of the first document 43x is 
continued. When a copying operation of the first document 43x is completed 
for a preset number of sheets in the Step n51 and when the count of the 
copying operation has reached the number of sheets containable in the 
intermediate tray 113 in Step n52, control moves to the Steps n11 through 
n18, and the contents of the second document 43y are copied onto the copy 
sheets P inverted upside down fed from the intermediate tray 113. 
When the copying operation is determined to have been completed for the 
preset number of sheets in Step n53, control moves to the Step n22, where 
the documents 43x and 43y are discharged to complete an operation. Also, 
when the copying operation is not completed in the Step n51 up to the 
preset number of sheets, control moves to Step n54, where it is determined 
whether the count of copying operations of the second document 43y has 
reached the number of the copy sheets P contained in the intermediate tray 
113, and in the case where it has not, control returns to the Step n18, 
where a copying operation of the second document 43y is continued. 
On the other hand, when a copying operation of the copy sheets P in the 
intermediate tray 113 is completed in the Step n54, which means when a 
preset number of sheets is larger than the number of sheets containable in 
the intermediate tray 113, control moves to the operation in the steps n23 
through n26, where the first document 43x is set in the exposure region W1 
again and a copying operation started. Then, it is determined whether a 
copying operation is completed up to a preset number of sheets in Step 
n55, and in the case where it is not, it is determined in Step n56 whether 
a copying operator is reached to the number of sheets containable in the 
intermediate tray 113, and in the case where it is not, control returns to 
the Step n26 and a copying operation of the first document 43x is 
continued. When a copying operation up to a preset number of sheets is 
completed in the Step n55, and when a copying operation is reached to the 
number of sheets containable in the intermediate tray 113 in Step n56, 
control moves to the operation in the Steps n27 through n30, and the 
second document 43y is set, then control returns to the Step n18, where a 
copying operation of the second document 43y is started. 
In this way, a copying operation of the documents 43 can be continued up to 
a preset number of sheets desired without restriction by the number of 
sheets containable in the intermediate tray 113, which improves an 
operability. Also in this embodiment, when the back-and-forth movement of 
the documents 43x and 43y has reached a specified number of times as 
described above, the documents 43x, 43y may be once discharged and 
circulated. 
The invention may be embodied in other specific forms without departing 
form the spirit or essential characteristics thereof. The present 
embodiments are therefore to be considered in all respects as illustrative 
and not restrictive, the scope of the invention being indicated by the 
appended claims rather than by the foregoing description and all changes 
which come within the meaning and the range of equivalency of the claims 
are therefore intended to be embraced therein.