Automatic document feeder comprising a guide member

An automatic document feeder includes a guide member which has a flexible thin piece. A plurality of recesses are formed in a free end of the guide member in spaced-apart relationship in a width direction to provide the plurality of recesses and a plurality of protrusions adjacent to the recesses. The recesses and protrusions are formed and disposed so that both side edges of original documents of various standard sizes may pass tip portions or outside edge portions of the protrusions. By this, both side edges of the original documents are without foil scopped by the protrusions. Accordingly, both edges of original documents do not enter the interior most portions of the recesses and thus a paper jam does not occur.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an automatic document feeder for an image 
forming apparatus such as an electrophotographic copying machine and a 
laser printer, and more particularly, to an automatic document feeder 
comprising a guide member for deflecting an orignal document being 
conveyed by conveying means. 
2. Description of the Prior Art 
In recent years, there have been many image forming apparatus, such as 
electrophotographic copying machines, each equipped with an automatic 
document feeder by which an original document is handled automatically. 
The operation of said automatic document feeder is explained as follows, 
exemplifying the electrophotographic copying machine. The automatic 
document feeder comprises conveying means such as a conveying belt and a 
feed roller. The conveying means automatically feeds the original document 
to a transparent plate disposed at an upper part of the body of the 
copying machine. The original document placed on the transparent plate is 
exposed to light. After the exposure, the original document is 
automatically conveyed out of and discharged from the transparent plate by 
the conveying means. At this time, the original document conveyed by the 
conveying means is deflected by a guide member in the discharging 
direction. 
Conventionally, the guide member is formed of a flexible thin piece such as 
a synthetic resin film, and normally, formed of a rectangular film of a 
predetermined size cut out in a rolled synthetic resin film. When the 
guide member formed of this rectangular film is used, one end of the guide 
member is fixed to a support member such as an iron plate and the other 
free end is elastically in contact with a predetermined portion. It is 
noted that the predetermined portion is a concave portion formed on the 
transparent plate, an upper surface of a receiving member disposed on a 
downstream side of the transparent plate in the conveying direction, or so 
like. 
However, if the free end of the guide member is formed straight, the free 
end waves in a width direction and is sectionally detached from said 
predetermined portion. Accordingly, a space occurs between the free end of 
the guide member and said predetermined portion and consequently, 
sometimes a front edge of the original document passing in the discharging 
direction is caught in said space which causes a paper jam. This problem 
occurs similarly even if the free end of the guide member is forcibly in 
contact with said predetermined portion. 
SUMMARY OF THE INVENTION 
The principal object of the present invention is to provide an automatic 
document feeder capable of deflecting without fail an original document 
being conveyed by conveying means without occurrence of a paper jam. 
In order to attain the object, an automatic document feeder of the present 
invention comprises a guide member comprised of a flexible thin piece, and 
a plurality of recesses are formed in a free end of a guide member in 
spaced-apart relationship in a width direction to constitute the plurality 
of recesses and a plurality of protrusions adjacent to the recesses. The 
recesses and protrusions are formed and disposed so that both side edges 
of original documents of various standard sizes may pass tip portions or 
outside edge portions of the protrusions. As such constructed, both edges 
of each of the original documents are scooped up by the protrusions 
without fail. Accordingly, both edges of the original documents do not go 
into most interior portions of the recesses and thus paper jam is 
prevented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Next, preferred embodiments of the present invention are described in 
conjunction with the drawings. 
FIGS. 1 through 6 show an embodiment of the present invention. FIG. 2 is a 
schematic view showing an example of an automatic document feeder. FIG. 3 
is a sectional view of an enlarged principal portion of the automatic 
document feeder of FIG. 2. 
In FIG. 2, a numeral 1 designates an electro-photographic copying machine 
as an example of an image forming apparatus and a transparent plate 2 is 
disposed on the upper side of said body 1. An exposure device disposed 
below the transparent plate 2 reciprocates in a direction of X-Y by a 
driving means (not shown). An automatic document feeder 4 is disposed on 
the copying machine body 1. A principal portion of the automatic document 
feeder 4 is rotatably attached to the copying machine body 1. The axis of 
the rotation is a line extending along an edge of the transparent plate 2 
and the rotation is between a close state with the transparent plate 2 
covered and an open state with the transparent plate 2 exposed. In FIG. 2, 
the principal of the automatic document feeder 4 is in the close state. 
The automatic document feeder 4 comprises a document tray 5 disposed on a 
right hand side in FIG. 2. Further, the feeder 4 comprises means for 
conveying an original document and as said conveying means, a paper feed 
roller 6, a pair of resist rollers 7, a conveying belt 8, and a document 
discharging mechanism 9 are disposed in this order along a conveying 
direction. The conveying belt 8 is disposed so as to be generally in touch 
with the upper surface 2a of the transparent plate 2 in said close state. 
As shown in FIG. 3, the document discharging mechanism 9 comprises a guide 
rib 11, a guide member 12, and a discharge roller 13. A document receiving 
portion 14 is disposed on an upper side of the automatic document feeder 4 
and on the downstream side of the document discharging mechanism 9 in the 
conveying direction. 
A document guide means 10 is disposed between the conveying belt 8 and the 
document discharging mechanism 9 in the conveying direction. The structure 
of the document guide means 10 is explained referring to FIGS. 1 and 3 as 
follows. 
The document guide means 10 comprises a support member 15 and a guide 
member 16. The support member 15 is made of a rigid body and is bent so as 
to form an appropriate angle. One end of the guide member 16 formed of a 
flexible thin piece is fixed on an upper portion 15a of the bent support 
member 15. A free end of the guide member 16 projects inclinedly so as to 
be directed to the transparent plate 2 and the conveying belt 8. The free 
end of the guide member 16 is elastically in contact with the upper 
surface 17a of a receiving member 17 disposed on downstream side of the 
transparent plate 2. As the free end of the guide member 16 is in contact 
with the receiving member 17, the distance of a path between the 
transparent plate 2 and the document receiving portion 14 can be short. 
Accordingly, a previous document can be discharged at the same time a 
subsequent document is fed to the transparent plate 2. Further, a 
downstream side roller of the conveying belt 8 can be coupled with the 
discharge roller 13 by a driving belt, thus the driving mechanism can be 
simplified. Still further, the whole apparatus can be compact. The guide 
member 16 will be described in detail later. 
The receiving member 17 is rotatable between a first position above the 
transparent plate 2 (shown by the alternate long and two short dashes line 
in FIG. 3) and a second position below upper surface 2a of the transparent 
plate 2 (shown by the continuous line in FIG. 3) around a rotation shaft 
17b. The width of the receiving member 17 is generally the same as that of 
the transparent plate 2. The rotation axes 17b and rotation regulate 
pieces 17c are protrudingly disposed at both sides of the receiving member 
17. In FIG. 1, only one of the two rotation axes 17b and only one of the 
two rotation regulate pieces 17c are shown. 
The receiving member 17 is attached to the upper side of the copying 
machine body 1 by attachment members 18 (in FIG. 1, only one of the two is 
shown). The attachment members 18 are disposed at both sides of the 
receiving member 17 in the width direction. Each of the attachment members 
18 comprises a hole 18a for rotatably supporting the rotation shaft 17b, a 
rotation regulate channel 18b, engaged with said rotation regulate piece 
17c for regulating a rotation range of the receiving member 17, a piece 
18c for pressing the transparent plate 2 downward, a vertical through hole 
18d, and two locating lugs (not shown) disposed at the lower side of the 
attachment member 18. On the other hand, a tapped hole 20 corresponding to 
the hole 18d of the attachment member 18 and two locating slots 21 
corresponding to the locating lugs of the attachment member 18 are formed 
at an upper side member 19 of the copying machine body 1. 
Each of the rotation shafts 17b of the receiving member 17 is inserted in 
each of the holes 18a of the attachment member 18. Each of the rotation 
regulate pieces 17c of the receiving member 17 is engaged with one 
rotation regulate channel 18b of the attachment member 18. Then, the 
locating lugs of the attachment member 18 are inserted in the slots 21 and 
a screw 22 is inserted downward in the hole 18d and the tapped hole 20 for 
fixing. By this, the attachment member 18 is fixed at a predetermined 
portion of the upper side of the copying machine body 1 and the receiving 
member 17 is rotatably supported by the attachment member 18 and is 
rotated around the rotation shaft 17b. The receiving member 17 is rotated 
within the range between the first position where the upper surface of the 
rotation regulate piece 17c is in contact with the inside upper side of 
the rotation regulate channel 18b and the second position where the lower 
side of the receiving member 17 is in contact with the upper side member 
19 of the copying machine body 1. As above-mentioned, when the receiving 
member 17 is located at the first position, the edge of the receiving 
member 17 is above the upper surface 2a of the transparent plate 2 and 
when the receiving member 17 is located at the second position, said edge 
is below said upper surface 2a. When the original document is located by 
hand on the transparent plate 2 with the automatic document feeder 4 being 
in the open state, the receiving member 17 is located at the first 
position and it makes easy to position the document on the transparent 
plate 2. On the other hand, when the automatic document feeder 4 is in the 
close state, the receiving member 17 is located at the second position so 
as not to prevent the original document from being discharged from the 
transparent plate 2 by using the automatic document feeder 4. The piece 
18c of the attachment member 18 supports the transparent plate 2 together 
with the edge of the upper side member 19 by the contact of a lower 
surface of the piece 18c with the upper surface 2a of the transparent 
plate 2. 
Further, leaf springs 23 (in FIG. 1, only one of the two is shown) are 
disposed between the receiving member 17 and the upper side member 19 of 
the copying machine body 1. The leaf spring 23 comprises the upper portion 
23a in contact with the lower side of the receiving member 17 and the 
lower portion 23b in contact with the upper side member 19. At the lower 
portion 23b, two through holes 23c are disposed which are engaged with 
locating lugs 19a disposed at the upper side member 19. The receiving 
member 17 is biased upward (in the direction of the first position) by the 
elastic power by the deformation of the leaf spring 23. When the automatic 
document feeder 4 is in the close state, the receiving member 17 is 
located downward (in the direction of the second position) against the 
elastic power of the leaf spring 23 by a positioning means such as a 
projection provided at the automatic document feeder 4. Thus, when the 
original document is fed by the automatic document feeder 4, the document 
passing the upper surface of the receiving member 17 located at the second 
position is deflected upward by the guide member 16. 
Next, the guide member 16 is described in detail as follows. As the guide 
member 16, a relatively thin and flexible member, for example, a synthetic 
resin film such as a polyethylene terephthalate of less than 0.1 mm in 
thickness and an electrically conductive metal foil is used. Referring to 
FIG. 4, the width of the guide member 16 is generally the same as that of 
the support member 15 and a plurality of recesses 24 are formed in the 
free end of the guide member 16 in spaced-apart relationship in the width 
direction. Each of protrusions 25 are formed between one recess 24 and 
another recess 24 adjacent to it. The guide member 16 thus comprises a 
plurality of recesses 24 and a plurality of protrusions 25 adjacent to the 
recesses 24, and only the protrusions 25 are in contact with the upper 
surface of the receiving member 17. The reason for this is to prevent the 
free end of the guide member 16 from waving in the width direction. If, as 
in a prior art guide member, the free end of the guide member is formed 
straight, it is difficult to make the whole of the free end completely in 
contact with the receiving member 17. Consequently, the free end of the 
guide member is sectionally detached from the receiving member 17 and the 
front edge of the document is caught in the detached portion, which causes 
a paper jam. On the other hand, as the guide member 16 of the present 
invention comprises a plurality of recesses 24 in its free end, the 
protrusions 25 can be made completely in contact with the receiving member 
17. Accordingly, the original document can be scooped up without fail by 
the protrusions 25 completely in contact with the receiving member 17. 
However, if the plurality of recesses are disposed in the guide member 16 
without considering the locations of the side edges of original documents 
of various standard sizes, the following problem is caused. FIG. 16 is a 
figure explaining a state where the problem is caused. In FIG. 16, one end 
of a guide member 53 is supported by a support member 52 and the free end 
of the guide member 53 is in contact with a receiving member 51. A 
plurality of recesses 54 are formed in the free end of the guide member 53 
in spaced-apart relationship in the width direction. In FIG. 16, only one 
recess 54 is shown. Protrusions 55 and 56 are adjacent to the recess 54. 
An original document 58 passes the upper surface of a transparent plate 57 
in the direction of an arrow Z. When the original document 58 is deflected 
upward by the guide member 53, sometimes a front part of a side edge 58a 
of the original document 58 does not get onto the protrusion 55 but goes 
into the recess 54 and the original document 58 goes with the front part 
of the side edge 58a crossing an inside edge portion 55a of the protrusion 
55. If the original document 58 goes farther, the front edge 58b of the 
original 58 is engaged with the interior most portion 54a of the recess 
54. Consequently, the guide member 53 cannot scoop up the original 
document smoothly, and a paper jam is caused. 
Further, description of this problem with more detailed analysis is as 
follows. Referring back to FIG. 4, each of the interior most portions 24a 
of the recesses 24 is disposed between the tip portion 25a of one 
protrusion 25 adjacent to the recess 24 and the tip portion 25a of another 
protrusion 25 adjacent to the recess 24. Consequently, if a plurality of 
recesses 24 and a plurality of protrusions 25 are formed without 
considering their relationship with both side edges of original documents 
of various standard sizes, as shown in FIG. 6, for example, the left side 
edge 26a of the original document can pass the outside edge portion 25c of 
the protrusion 25 as shown by the continuous line, or, can pass the inside 
edge portion 25b of the protrusion 25 as shown by the alternating long and 
two short dashes line. The following is a more detailed description. The 
protrusion 25 can be divided into two parts: an outside part including the 
outside edge portion 25c located outside (in FIG. 6, on the left of) a 
line T which goes across the tip portion 25a of the protrusion 25 in the 
conveying direction; and an inside part including the inside edge portion 
25b located inside (in FIG. 6, on the right of) the line T. As shown in 
FIG. 3, the guide member 16 inclinedly projects with its free end in 
contact with the upper surface 17a of the receiving member 17. Only the 
tip portion 25a is in contact with the upper surface 17a and the rest of 
the protrusion is detached from the upper surface 17a. Accordingly, when 
the left edge 26a of the original document 26 passes the inside edge 
portion 25b as shown by the alternating long and two short dashes line, as 
a portion around the left front corner of the original document 26 does 
not pass the tip portion 25a, the left front corner portion of the 
original document 26 is not scooped up by the guide member 16. And the 
left front corner portion goes behind the guide member 16 through the 
recess 24 and crosses the inside edge portion 25b. Consequently, if the 
original document 26 goes farther, as shown in FIG. 17, the front edge 26b 
of the original document 26 engages with the interior most portion 24a of 
the recess 24 and a paper jam is caused. 
On the other hand, when the left edge 26a of the document 26 passes the tip 
portion 25a or the outside edge portion 25c of the protrusion 25 as shown 
in the continuous line, the portion around the left front corner of the 
original document 26 passes the tip portion 25a of the protrusion 25. 
Accordingly, as shown in FIG. 5, the corner portion of the original 
document 26 is scooped up by the tip portion 25a without fail. So if the 
recesses 24 and the protrusions 25 are formed and disposed so that both 
side edges of original documents of various standard sizes may pass only 
the tip portions 25a or the outside edge portions 25c and may not pass the 
inside edge portions 25b, any original documents 26 are guided by the 
guide member 16 without fail and without a paper jam. 
Accordingly, in FIG. 4, the relationship between the guide member 16 and 
both side edges of original documents of various standard sizes is as 
follows. The sizes of documents specified by JIS, that is, A3 through A5R 
are shown in alternating long and two short dashes lines at the bottom of 
FIG. 4. As is clear from FIG. 4, the recesses 24 and the protrusions 25 
are formed and disposed so that both side edges of original documents of 
various standard sizes may pass only the tip portion 25a or the outside 
edge portion 25c of the protrusions 25 and may not pass the inside edge 
portions 25b. 
FIG. 5 is a view showing how the left side edge 26a of the original 
document 26 passes. As for the right side edge of the original document 
26, different from FIG. 6, the outside in FIG. 6 is the inside and the 
inside in FIG. 6 is outside. In the embodiment shown in FIG. 4, as the 
center of original documents passes the center line CL, the form and 
location of the recesses 24 and the protrusions 25 are symmetrical with 
respect to the center line CL. Also, the outside edge portions 25c and the 
inside edge portions 25b of the protrusions 25 are symmetrical with 
respect to the center line CL. 
Further, in the embodiment shown in FIG. 4, the form of each protrusion of 
a first set of the protrusions 25 around the center line CL is 
symmetrical, but on the other hand, where both side edges of various 
standard sizes mainly pass and far from the center line CL, the recesses 
24 extend outside and the form of each protrusion of a second set of the 
protrusions 25 is not symmetrical. This is a result of making both side 
edges of various standard sizes pass only the tip portions 25a or the 
outside edge portions 25c of the protrusions 25 and not pass the inside 
edge portions 25b. 
If each of the protrusions is the protrusion 125 shown in FIG. 7, which is 
completely asymmetrical, when the protrusion 125 is elastically in contact 
with the receiving member 17, the protrusion 125 is not in contact with 
the receiving member 17 at the tip portion 125a, but at a point 125d in 
the outside edge portion 125c. The directions of the pressing and the 
extending direction of the protrusion are different and thus, as shown in 
FIG. 8A, said point 125d is in contact with the receiving member 17, but 
as shown in FIG. 8B, there is a possibility that the tip portion 125a is 
detached a little from the receiving member 17. Consequently, there is a 
possibility that the front edge 26b of the original document 26 is caught 
in the interior most portion 24a of the recess 24 after the document 26 
passes the tip portion 125a, which causes a paper jam. 
From this viewpoint, it is preferable that each of the protrusions are 
formed symmetrically. Even if each of the protrusions are not formed 
symmetrically, it is preferable that at least a portion around the tip 
portion 225a of the protrusion 225 is formed symmetrically, as in the 
protrusion 225 shown in FIG. 9. Accordingly, in FIG. 4, where both side 
edges of various standard sizes mainly pass and far from the center line 
CL, the protrusions 25 are formed as shown in FIG. 9. 
Further, in the guide member 16 shown in FIG. 4, the tip portions 25a' of 
the two protrusions 25 where both side edges of B4(B5) and A3(A4) 
documents which are relatively large sizes pass, is formed flatly. Instead 
of this, as shown in FIG. 10, the recesses 24 and protrusions 25 may be 
formed and disposed so that both side edges of B4(B5) and A3(A4) documents 
may pass only the tip portions or the outside portions of the protrusions 
25. Further, as shown in FIG. 11, protrusions 25' having tip portions 25a' 
of flat forms may be formed not only at the ends of the guide member 16 in 
the width direction but all over the guide member 16 in the width 
direction and the same outside edge portion of a protrusion may be 
commonly used for original documents of a plurality of (for example, two 
kinds of) sizes. 
FIG. 12 is a view showing another embodiment of a guide member of the 
present invention. In this embodiment, recesses 324 extend outward and the 
interior most portion 324a of each of the recesses 324 is disposed to be 
located outside tip portions 325a of the two protrusions adjacent to the 
recess 324 in the width direction. A more detailed description referring 
to FIG. 13 is as follows. The most interior portion 324a of the recess 324 
is located outside a line T' extending in the conveying direction which 
passes the tip portion 325a of the protrusion 325 which is outside (the 
left hand side in FIG. 13) the recess 324 and which is adjacent to the 
recess 324. Accordingly, as shown in FIGS. 13 and 14, the left side edge 
26a of the original document 26 always passes the tip portion 325a or an 
outside edge portion 325c of the protrusion 325. Accordingly, different 
from in the above-mentioned embodiments of FIGS. 4 through 11, it is not 
necessary to prevent both side edges of an original document from passing 
the inside edge portions. Thus, as the left side edge 26a of the original 
document 26 always passes the outside edge portion 325c of the protrusion 
325, the portion around the left front corner of the original document 26 
always passes the tip portion 325a of the protrusion 325. Accordingly, as 
is shown in FIG. 14, the left front corner of the original document 26 is 
scooped up by the tip portion 325a without fail, and thus the original 26 
can be guided upward without fail. The forms and locations of the recesses 
324 and the protrusions 325 of the guide member 16 in FIG. 12 are, as well 
as those in FIGS. 4, etc., symmetrical with respect to a center line CL. 
By this, both side edges of original documents of various standard sizes 
can be guided without fail. 
Further, as is shown especially clearly in FIG. 14, only the tip portion 
325a of the protrusion 325 may be formed symmetrically. If the tip portion 
325a is formed like this, as was explained according to FIG. 9, the tip 
portion 325a of the protrusion 325 is not detached from the receiving 
member 17 and thus the front edge 26b of the original document 26 is not 
caught. However, if the tip portion 325a is formed like this, strictly 
speaking, it is possible that a side edge of the original document passes 
a location a little off the tip portion 325ainward. Accordingly, it is 
possible that either of the corners of the original document 26, without 
being scooped up by the tip portion 325a, goes behind the guide member 16 
through the recess 324. But, as the most interior portion 325a of the 
recess 324 is disposed outside the tip portion 324a, the front edge of the 
original document 26 does not engage with the most interior portion 324a. 
That is, even if only a corner of the original document 26 goes behind the 
guide member 16 at one time, the corner goes upward again through the 
recess 324, passes the outside edge portion 325c of the protrusion 325, 
and, with the rest of the original, is guided upward by the guide member 
16. 
Further, as shown in FIG. 15, the protrusions 325' having flat tip portions 
325a' as well as the ones shown in FIG. 11 may be formed in the width 
direction all over the guide member 16 which has the recesses 342 
extending outward and the same outside edge portion of a protrusion may be 
commonly used for original documents of a plurality of (for example, two 
kinds of) sizes. 
In all the above-mentioned embodiments, the guide member 16 applies to an 
image forming apparatus which copies the original document 26 with the 
center of the original document 26 corresponding with the center of the 
width of the image forming apparatus. However, a guide member with the 
recesses and protrusions formed so that both side edges of original 
documents of various standard sizes may pass the outside edge portions of 
the protrusions is suitable for an image forming apparatus which copies 
the original document 26, with one side edge of the original document 26 
being a standard line of copying. Accordingly, the guide member may be 
asymmetrical with respect to the center line CL. 
Further, in the above-mentioned embodiments, the free end of the guide 
member 16 is in contact with the upper surface 17a of the receiving member 
17, but the free end may go into a recess formed in the upper surface 2a 
of the transparent plate 2. Further, the free end of the guide member 16 
may be in contact with the side of the transparent plate 2 which is cut 
appropriately. Still further, the free end of the guide member 16 may be 
in contact with the upper surface of a stationary-type receiving member 
specially disposed on the downstream side of the transparent plate 2. 
Further, in the above-mentioned embodiments, the guide member 16 is 
disposed on the downstream side of the transparent plate 2 and the guide 
member 16 is constructed so as to guide an original document after 
exposure in the discharging direction, but the guide member 16 may be 
disposed wherever an original document being conveyed in a a predetermined 
direction by conveying means should be deflected in another direction. 
More generally, the guide member can apply wherever a sheet member being 
conveyed should be deflected. For example, in an image forming apparatus 
capable of duplex copying, the guide member 16 is suitable for a sheet 
path where a sheet material is conveyed to an intermediate tray, after one 
surface of which is copied, or another sheet path where a sheet material 
is conveyed from the intermediate tray to a transfer portion.