JP2617796B2 - Document feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder applied to a facsimile, a copying machine, a printer, or the like.

<Conventional technology> In a facsimile or the like, a document is transported by a transport unit to an optical reading system at a predetermined speed and the content thereof is read.
It is sent to the recording system.

FIG. 9 shows an example of a document transport reading system provided in a facsimile or the like.

According to the figure, when a plurality of originals S are set on the original mounting table 100 also serving as a device cover and a reading operation is performed, several originals S from the bottom of the set plural originals S are placed on the original mounting table. While being guided by a document guide 110 provided on substantially the same horizontal plane as 100, the sheet is conveyed by a preliminary conveying roller 120 and a pressing member 130 pressed against the same, and is separated one by one by a separation roller 140 and a pressing member 150 pressed against the same. .

Then, the separated document S is transported by the pair of transport rollers 160a and 160b.
While passing through the optical reading means 180 by 170a and 170b, light is emitted from the light source 180a of the optical reading means 180, and the reflected light is transmitted through the mirror 180b and the lens 180c.
The light enters a photoelectric conversion element 180d such as a CCD and is converted into an electric signal, and this signal is transmitted to a predetermined recording system.

<Problems to be Solved by the Invention> In the above-described original transport reading system, in order to surely separate the originals S stacked one by one in the separation unit including the separation roller 140 and the pressing member 150, a plurality of originals S are stacked. It is desirable that the leading end portion of the bundle of originals be separated and the end surface of the leading end portion be wedge-shaped as shown in FIG. 4 (b). As shown in FIG. 10, the leading end of the bundle of originals is not stepped, and the end face of the leading end is
In some cases, the sheet may be conveyed to the separation roller 140 while being perpendicular to the upper surface.

For this reason, the conveying force of the preliminary conveying roller 120 is set to be large, and the leading end of the bundle of documents is separated by the preliminary conveying roller 120 so that the end surface of the leading end becomes a wedge shape from a right angle state, or the separation roller 140 Means have been taken, such as separating the sheets one by one while setting the conveying force large while separating the leading end of the document bundle, that is, breaking the end face of the leading end portion into a wedge shape from a right angle state. Document S
, The frictional force between the originals S becomes large, and there is a possibility that so-called double feed (multiple feed) in which the originals S are conveyed while being overlapped without being separated from each other.

As a means for solving such a defect, for example, it is conceivable that the document guide 110 is inclined downward with respect to the document table 100.

In this way, the leading end of the document bundle is
It is possible to bend and bend along 0, and it is not necessary to set the transport force of the preliminary transport roller 120 and the transport force of the separation roller 140 large.

However, when the document S moves off the separation roller 140 and moves to the substantially horizontal optical reading unit 180, the trailing edge of the document S fluctuates due to a change in the transport path that changes from an inclined path to a horizontal path. Therefore, there is a possibility that a good image cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to surely separate documents one by one and transport the documents to a document reading means so as to obtain a good read image. To provide a document transport device capable of performing such operations.

<Means for Solving the Problems> Means for solving the above problems and applied to the embodiment described below include a document table on which a document is placed, and a document conveyed from the document table by the conveyance unit. A separating unit that separates each sheet and conveys the document to the document reading unit, a guide unit that is inclined with respect to the document mounting table so as to guide the document from the document mounting table to the separation unit, and a document reading unit. And a sub-guide portion which guides both end portions in the width direction of the document in the vicinity of the separation portion with a gentle inclination.

Further, the sub-guide portion is formed by recessing both end portions in the width direction of the guide portion.

In addition, the sub-guide portion is 45 degrees from the center of the guide portion.
It is characterized in that it is formed in the range of mm to 150 mm.

<Operation> According to the above-described means, when the leading end of a plurality of originals (original bundle) stacked on the original placing table is pushed into the entrance side of the separation unit, the leading end bends along the guide portion, And the end face of the tip portion becomes wedge-shaped.

Then, when the reading operation of the document is started, the documents are separated one by one by the separation unit and conveyed to the document reading unit.

Here, since both ends in the width direction of the document are guided by the sub guide portion which is gently inclined with respect to the document reading portion, when the rear end of the document comes off the separation portion and shifts to the document reading means, the document is scanned. The deflection at both ends in the width direction can be suppressed as small as possible.

<Embodiment> Hereinafter, an embodiment of the document feeder according to the above means will be described.

(First embodiment)

FIG. 1 is a side sectional view of the document feeder, FIG. 2 is a perspective view of the document feeder, FIG. 3 is a cross-sectional view of an entire facsimile provided with the document feeder, and FIGS. () Is an explanatory diagram showing an end surface state of the leading end of the document bundle.

First, an outline of the entire facsimile will be described with reference to FIG.

In FIG. 3, reference numeral A denotes a main body of the facsimile apparatus, which comprises a document transport reading system B and a recording system C.

The facsimile machine body A
The original placing table 2 also serving as a cover, a preliminary transporting section 3 including a preliminary transporting roller 4 for transporting the original S from the original placing table 2 and a pressing member 5 for pressing the original S, and transported by the preliminary transporting section 3 The document feeder 1 includes a separation roller 7 for separating the originals S one by one and a separation unit 6 including a pressing member 8 pressed against the separation roller 7.

Also, an optical reading unit 11 (an original platen glass 11a as a reading unit, a light source 11b, a mirror 11) for reading the original S transported from the original transporting apparatus 1 is provided in the original transport reading system B.
c, a lens 11d, a photoelectric conversion element 11e including a CCD, etc., a pair of original feed rollers 12a and 12b arranged on the entrance side (the right side in FIG. 3) of the optical reading means 11, and an optical reading means.
An original discharge roller pair 13a, 13b, etc., arranged on the outlet side of 11 (the left side in FIG. 3) are provided.

Further, the recording system C includes a storage section 17 for storing a roll-shaped recording sheet 16, a platen roller 18 for pulling out the roll-shaped recording sheet 16 from the storage section 17, and a roll-shaped sheet drawn by the platen roller 18. Decal mechanism 19 (Decal shaft 19) for removing the curl of the recording sheet 16
a, a guide shaft 19b) and a recording head for recording a predetermined image on the recording sheet 16 drawn out by heat generated by both signals.
20, a cutter 21 for cutting the rear end of the recording sheet 16 on which a predetermined image is recorded, a paper discharge roller 22 for discharging the cut recording sheet 16, a stacker 23, and the like.

Next, the portion of the document feeder 1 will be described in detail with reference to FIGS.

At the center of the upper surface of the document table 2, sliders 2a and 2b for aligning both sides of the document S and guiding the both sides are arranged in the direction of the arrow shown in FIG. ).

Further, a preliminary transport roller 4 constituting the preliminary transport section 3
Is disposed at a position lower than the upper surface of the document table 2, and the separation roller 7 constituting the separation unit 6 is disposed at a position lower than the preliminary conveyance roller 4.

A window hole through which the preliminary transport rollers 4 and 4 and a part of the separation roller 7 are exposed is provided between the document table 2 and the separation unit 6.
A guide portion 9 having downwards inclination having 9a, 9a, 9b is provided.

The guide section 9 guides the document S from the document table 2 to the separation section 6, and is inclined downward from near the upstream side in the conveyance direction of the preliminary conveyance roller 4 to near the downstream side of the separation roller 7.

Accordingly, a plurality of documents S are set on the document table 2 in a stacked state, and the leading end portion of the stacked documents S (document bundle) is moved along the guide portion 9 with the separation roller 7 of the separation portion 6 and the pressing member 8. 4A (in the vicinity of the upstream of the separating portion 6), the leading end portion is bent with respect to the portion placed on the document table 2 as shown in FIG.
As a result, the distal end portion is separated, and the end surface of the distal end portion becomes wedge-shaped. That is, as shown in FIG. 6B, the end face of the tip portion follows the press-contact member 8 having an inclined surface.

Here, the inclination angle θ _{1 of the} guide portion 9 with respect to the upper surface of the document table 2 (see FIG. 1) is determined when the leading end portion of the document bundle is pushed along the main guide portion 9 near the upstream of the separation portion 6. It is sufficient that the front end portion is separated and the end surface of the front end portion is set to be wedge-shaped, and varies depending on the material, thickness, number of sheets, etc. of the original S, but within a range of 5 to 30 degrees. Is set.

In addition, at the both ends in the width direction of the guide portion 9 orthogonal to the document conveyance direction, that is, at the portions where the both ends in the width direction of the document S overlap, the sub guide portion 9c from the center position of the preliminary conveyance roller 4 to the separation roller 7 position, 9c is formed.

The sub-guide portion 9c is formed by depressing the upper surface at both ends in the width direction of the guide portion 9 and its bottom surface 9c 'is gently inclined with respect to the substantially horizontal document guide surface 11f of the document reading means 11. Is set to

Here, the width L of the sub guide portion 9c (see FIG. 2, L = L ₁ −
L ₂ ) is, for example, 85 mm from the center of the guide section 9 so as to be able to correspond to originals S of various sizes such as A4 size (210 mm), B4 size (257 mm), and A3 size (297 mm).
(L ₂ ) to about 150 mm (L ₁ ). A4
For example, the size of the original S can be set to 45 mm (L ₂ ) to 150 mm (L ₁ ) from the center of the guide section 9 so that the original S that is smaller than the size, for example, an A6 size (105 mm) original can be handled.

When the sub guides 9c, 9c are provided in this manner, even when the rear end of the original S is disengaged from the separation roller 7 when the original S is conveyed and moves to the substantially horizontal original guide surface 11f from the inclined guide 9 (conveyance path). Before the document S is separated from the separation roller 7, the document guide surface 11f
Is guided by the sub-guide portion 9c that is gently inclined with respect to the direction, and the change in the transport path is small. Therefore, the shake is small, and the disturbance of the read image can be suppressed as small as possible.

The operation of the sub guide portion 9c will be described with reference to comparative examples shown in FIGS.

FIG. 5 shows the document feeder 1 in the case where the sub guide portion 9c is not provided. In this case, as shown in FIG. The document S is conveyed by the original discharge rollers 13a and 13b, and at this time, the original S is not slack because the conveying speed of the original discharge roller 13b is set faster than the conveying speed of the original paper feed roller 12b. And a substantially horizontal document guide surface 11f extending from the guide portion 9 and the document guide surface 1f.
The document is conveyed at a substantially intermediate height position of an upper document guide 9d provided substantially parallel to 1f. When the trailing edge of the document S is disengaged from the separation roller 7 and moves to the document guide surface 11f,
As shown in FIG. 7, the transport path suddenly changes from an inclined state to a horizontal state, and at this time, the original S swings up and down between the original guide surface 11f and the upper original guide 9d due to the strain of the original S itself. (See the part surrounded by the two-dot chain line in the figure).
Both ends in the width direction of the document S are not held by the document feed roller 12b immediately after being separated from the separation roller 7 like the central portion of the document S, and therefore, swing in the vertical direction in particular.

The sub-guide portion 9c guides both ends in the width direction of the document S before leaving the separation roller 7 to reduce a change in the conveyance path, thereby reducing the deflection.

This will be described in more detail with reference to FIG. 8, which shows the relationship between the shake of the document S and the amount of deviation in reading.

In the reduction optical system using the lens 11d as in the document reading means 11, the maximum document reading width D is very large with respect to the diameter of the pupil of the lens 11d, and as shown in FIG. Becomes larger (θ _a <θ _b ).

On the other hand, when the document is lifted up from the original reading position (the position shown by the solid line in the figure at the intermediate height between the original guide surface 11f and the upper original guide 9d) due to the shake (moved to the dotted line position in the figure) The larger the angle of view, the greater the amount of reading deviation.

That is, the reading deviation amount in the middle portion of the original S is
X _a, the angle of view and theta _a, also a reading shift amount in the widthwise side portion X _b, the angle of view and theta _b, if the middle portion of the original S, the floating amount of the width direction both end portions was l _{, X a = l × sinθ a} , becomes a _{X b = l × sinθ b,} θ a <θ b (sinθ a <sinθ b) since it is, floating amount of the intermediate portion and both lateral end portions of the document S l However, the read misalignment amount is larger at both ends in the width direction of the document S than at the middle portion ( _Xa < _Xb ). Since practice swings in the vertical direction, the reading shift amount of X _a, X _b 2
Double.

For this reason, although the read image is disturbed, the shift amount _Xa is small in the middle portion of the document S and the image disturbance is not conspicuous, but the shift amount _Xb is large at both ends in the width direction, and the image disturbance is remarkably apparent. I will.

The sub-guides 9c, 9c reduce the deviation _Xb at both ends in the width direction of the document S, thereby reducing the read deviation amount _Xb , thereby minimizing the disturbance of the read image.

The reason why the sub-guide portion 9c is not provided at the center of the guide portion 9 is as follows.

In other words, if the sub-guide portion 9 is also provided at the center portion of the guide portion 9 to make the inclination gentle, the original S and the pressing member 8 (friction piece 8) necessary for enhancing the separation performance of the original S are improved.
a) and the guide section 9 cannot be secured.
The separation roller 7 and the preliminary conveyance roller 4
This is because it becomes impossible to secure a space for arranging the mechanical components such as.

Also, the guide portion 9 is provided between the sliders 2a and 2b.
A wedge-shaped member 10 is provided which is inclined so as to be lower on the side and higher on the side remote from the guide portion 9.

The wedge-shaped member 10 slightly lifts the rear end portion of the bundle of originals so that the lowermost original S is separated from the preliminary transport roller 4 (a gap is formed between the lowermost original S and the auxiliary roller 4). Even if the lowermost document S does not separate from the preliminary transport roller 4, the weight of the document bundle hardly acts on the preliminary transport roller 4, or the leading end of the document bundle abuts against the separation roller 7 and It is prevented that the sheet is not conveyed to the downstream side in the conveying direction (toward the optical reading unit 11).

That is, depending on the material, thickness, number of sheets, etc. of the document S,
The force (strain) of resistance to bending is large, and there is a possibility that the document S may not be bent along the guide portion 9 but bend into a curved shape. For this reason, the lowermost document S may be separated from the preliminary transport roller 4. To prevent

Here, the inclination angle theta ₂ with respect to the document table 2 the upper surface of the wedge-shaped member 10 is smaller than the inclination angle theta ₁ of the guide portion 9 is set to be about 5 ° to 25 °.

To set such an angle range, the wedge-shaped member 10
The inclination angle theta ₂ Gayori also small and the effect can not be obtained in which a wedge-shaped member 10, also the inclination angle theta ₂ of the wedge-shaped member 10
Is larger than 25 °, the guide portion 9 makes it impossible to align the front end portion of the bundle of originals along the pressing member 8 as shown in FIG. 4B.

The height e of the wedge-shaped member 10 is the sliders 2a and 2b.
Is lower than the height f of the original, the original bundle does not protrude from the sliders 2a and 2b, and the original S is moved by the sliders 2a and 2b.
Both sides are guided.

Further, the width g of the wedge-shaped member 10 is determined by the sliders 2a and 2b.
The distance between the sliders 2a and 2b when the sliders 2a and 2b are closest to each other is set smaller than h, so that the sliders 2a and 2b do not hinder the movement.

Furthermore, the tip of the wedge-shaped member 10 is
It is located almost on the same line as the front end surfaces of a and 2b. When the tip of the wedge-shaped member 10 protrudes from this position, the wedge-shaped member 10 approaches the guide portion 9 too much, and the operation cover 14 (see FIG. 3) hinders the setting of the document S.
The original bundle cannot be deformed so that the weight of the original bundle is sufficiently applied to the preliminary transport roller 4. If the tip of the wedge-shaped member 10 retreats from the position and is too far from the guide portion 9, the effect of providing the wedge-shaped member 10 cannot be obtained.

The document transport reading system B is covered with an operation cover 14 except for the document table 2. And
Although not shown, the operation cover 14 is provided with various operation keys and the like on the front side, and an electronic circuit and the like on the back side.

Also, on the back side of the operation cover 14, the pressing member 5,
When the operation cover 14 is opened with the document feed roller 12b and the document discharge roller 13b attached, the press contact members 5, 8, the document feed roller 12b, and the document discharge roller 13b are connected to the facsimile apparatus body A. Aside from the preliminary transport roller 4, the separation roller 7, the document feed roller 12a, and the document discharge roller 13a mounted on the side, the jam of the document S can be easily performed.

Further, the preliminary transport roller 4 of the preliminary transport section 3 includes a circumferential portion and a flat portion, and is formed in a substantially elliptical shape. The pressing member 5 of the preliminary transport section 3 is swingably attached to the back side of the operation cover 14 via a pin 5a, and is urged toward the preliminary transport roller 4 by a spring (not shown). It is in pressure contact with the preliminary transport roller 4. And
When the preliminary conveying roller 4 rotates and the circumferential portion faces the pressing member 5, the circumferential portion presses the pressing member 5, and when the flat portion faces the pressing member 5, the flat portion and the pressing member 5 A gap is created between the document S and the document S, whereby the document S is intermittently conveyed.

The pressure contact member 8 of the separating portion 6 is attached to the friction piece 8a and the back side of the operation cover 14 so as to be swingable.
8a against the separation roller 7 and a friction piece holder 8c and a spring 8c
The spring force of the spring 8c acts on the friction piece 8a via the friction piece holder 8b, whereby the friction piece 8a is pressed against the separation roller 7.

The document feed roller 12b and the document discharge roller 13b
When the operation cover 14 is closed, the pressing force of the pressing spring 15 urges the document feed roller 12a and the document discharge roller 13a.

Further, the document table 2 is a facsimile apparatus main body A.
Is provided so as to be able to open and close with the pin 2c as a fulcrum, so that the accommodating portion 17 can be opened when the roll-shaped recording sheet 16 is replaced or the like.

Further, a decurling shaft 19 a constituting the decurling mechanism 19 of the recording system C is provided on the back side of the document table 2. Also, guide shaft 19 of decal mechanism 19
b rotates as shown by the dotted line in FIG. 3 with the pin 19c as a fulcrum as the winding diameter of the recording sheet 16 decreases, so that the winding angle of the recording sheet 16 with respect to the decal shaft 19a increases. I have. That is, since the degree of curl increases as the diameter of the recording sheet 16 decreases, the curl of the recording sheet 16 is removed by increasing the wrapping angle with respect to the decurling shaft 19a.

 In FIG. 3, reference numeral 24 denotes a power supply for the main body A of the facsimile apparatus.

 Next, the operation of the first embodiment will be described.

At the time of reading a document, a plurality of documents S are set on the document table 2 in a stacked state, and the leading end of the loaded document S (document bundle) is guided along the guide portion 9 to the separation roller 7 of the separation portion 6. It is pushed down to the space 6a formed by the pressing member 8.

At this time, the document S is detected by a document sensor (not shown) provided on the inner surface side of the operation unit 14 near the preliminary transport roller 4, and the preliminary transport roller 4 and the separation roller 7 are moved in the direction of the arrow shown in FIG. Rotate to push the bundle of documents smoothly. Further, the leading end of the bundle of originals is bent along the guide portion 9 and separated, and the end surface of the leading end becomes wedge-shaped. Weight acts on the preliminary transport roller 4.

When the document reading operation is started, the preliminary transport roller 4, the separation roller 7, the document feed roller 12a, and the document discharge roller 13a rotate in the direction of the arrow shown in FIG.
Are separated one by one in the separation unit 6 and the optical reading means 11
Sent to

At this time, both ends in the width direction of the document S are guided by the sub guide portions 9c, 9c before the trailing edge of the document S comes off the separation roller 7.

Then, when the document S passes through the platen glass 11a of the optical reading unit 11, the document S is irradiated with light from the light source 11b, and the reflected light is transmitted through the mirror 11c and the lens 11d to the photoelectric conversion element 11e.
And is converted into an electric signal and transmitted to a predetermined recording system.

Further, at the time of recording, the platen roller 18 rotates, the roll-shaped recording sheet 16 is pulled out from the storage section 17, the curl is removed by the decurling mechanism 19, and the sheet is conveyed to the recording head 20. And a recording head that generates heat in accordance with an image signal
The predetermined image is recorded on the recording sheet 16 by the
The trailing edge of the image is cut by 21 and is discharged to the stacker 23 by the discharge roller 22.

According to the first embodiment, at the time of reading a document, the leading end portion of the document bundle is bent along the guide portion 9,
As a result, the end surface of the front end portion becomes wedge-shaped, so that the conveying force of the preliminary conveying unit 3 and the separating unit 6 is increased (the pressing force of the pressing member 5 against the preliminary conveying roller 4 and the separation of the pressing member 8). There is no need to separate the document bundle (by increasing the pressing force against the roller 7), and the so-called double feed (multiple sheet feed) in which the documents S are conveyed while being stacked without being separated from each other.
Does not occur.

Both ends in the width direction of the document S are guided to the sub-guides 9c and 9c (bottom surface 9c ') which are gently inclined with respect to the document guide surface 11f in the vicinity of the separation portion 6, that is, before leaving the separation roller 7. Therefore, the rear end of the document S is
If the transport path suddenly changes from the inclined state to the horizontal state due to the deviation from the optical reading means 11, the width of both ends in the width direction of the document S is small, and the read image of the same part may be disturbed. It can be kept as small as possible.

Furthermore, since the preliminary transport roller 4 and the separation roller 7 are located below the document table 2, the amount of the operation cover 14 that covers them and the projection of the document table 2 upward is reduced, and the facsimile apparatus body A Can be lowered. Further, since there is no need to increase the pressing force of the pressing member 8 against the separation roller 7, that is, the pressing member 8
The pressing member 8 is laid down (the inclination angle of the pressing member 8 is reduced), and the facsimile apparatus body A
Can be lowered.

Furthermore, the trailing end of the document bundle is slightly lifted by the wedge-shaped member 10, and the leading end of the document bundle does not rise from the preliminary transport roller 4 or hit the separation roller 7. The transfer force is reliably transmitted to S.

[Other embodiments]

In the first embodiment, the case where the guide section 9 is formed separately from the original placing table 2 is shown, but the guide section 9 and the original placing table 2 may be integrally formed. In this case, when the guide unit 9 and the document table 2 are opened, the operation cover is
14 can be opened at the same time.

Further, in the first embodiment, the case where the sub guide portion 9c is provided integrally with the guide portion 9 has been described, but it may be configured separately.

<Effects of the Invention> As described above, according to the present invention, a document table on which a document is placed and a document conveyed from the document table by the conveyance means are separated one by one and conveyed to the document reading means. Separating means, a guide portion inclined with respect to the document placing table so as to guide the document from the document placing table to the separating means, and a portion gently inclined with respect to the document reading means near the separating section. And a sub-guide portion for guiding both ends of the original in the width direction, the original can be separated one by one and conveyed to the original reading means so that a good read image can be obtained.

Further, if the sub-guide portion is formed by recessing both end portions in the width direction of the guide portion, the number of components does not increase, and the manufacturing cost can be reduced.

Also, the sub-guide part is 45mm ~ 150m from the center of the guide part.
If it is formed within the range of m, it can be applied to originals of various sizes.

[Brief description of the drawings]

1 to 4 (a) and (b) show a first embodiment of the present invention. FIG. 1 is a side sectional view of a document feeder, and FIG.
FIG. 3 is a perspective view of the document feeder, FIG. 3 is a cross-sectional view of the entire facsimile provided with the document feeder, FIG.
(B) is an explanatory view showing an end surface state of the leading end of the document bundle;
5 to 7 show a comparative example in which the sub-guide portion is not provided, FIG. 5 is a perspective view of a document transport device having no sub-guide portion, and FIGS. 6 and 7 are the same document transport devices. FIG. 8 is a side sectional view for explaining a document conveying state in the apparatus, FIG. 8 is an explanatory diagram showing a relationship between a shake of a document S and a reading deviation amount, and FIGS. FIG. 9 is a partial sectional side view of a conventional document feeder, and FIG. 10 is an explanatory view showing a state of an end face of a leading end portion of a document bundle in the document feeder. A is the main body of the facsimile machine, B is the original conveyance reading system,
C is a recording system, 1 is a document conveying device, 2 is a document placing table, 3 is a preliminary conveying portion, 4 is a preliminary conveying roller, 5 is a pressing member, 6 is a separating portion, 7 is a separating roller, 8 is a pressing member, 9 is a pressing member. Is a guide portion, 9c is a sub guide portion, 9c 'is a bottom surface, and S is a document.

Claims (3)

(57) [Claims] An original mounting table for mounting an original; separating means for separating the originals conveyed from the original mounting table by a conveying means one by one and conveying the original to a document reading means; A guide portion inclined with respect to the document table so as to guide the document from the table to the separation means; and a gentle inclination with respect to the document reading means to guide both ends in the width direction of the document near the separation section. And a sub-guide unit. 2. The document feeder according to claim 1, wherein the sub-guide portion is formed by recessing both ends in the width direction of the guide portion. 3. The document feeder according to claim 1, wherein the sub-guide portion is formed within a range of 45 mm to 150 mm from the center of the guide portion.