JP2000038234A - Document conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive a document conveying device by a small-sized motor without necessitating an additional object, prevent the fluctuation of speed of a document substantially completely, and reduce the fluctuation in the drive of a post- conveying roller immediately after a rear end of the document leaves a pre- conveying roller and the pre-conveying roller. SOLUTION: A PS roller 32 and a conveying roller 42 which convey a document 3 are provided in the front and rear in the direction of document conveyance, respectively, and a document reading position 27a exists between the PS roller 32 and the conveying roller 42 in the front and rear. A drive system of the PS roller 32 and the conveying roller 42 is first transmitted to the conveying roller 42 on the sheet discharge side in the direction of document conveyance more than the document reading position 27a from a motor 51 and then is transmitted to the PS roller 32 on the sheet input side in the direction of document conveyance more than the document reading position 27a. A peripheral speed of the coveying roller 42 is higher than a peripheral speed of the PS roller 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, which is provided with transport driving rollers for transporting a document in a document transport mechanism before and after in a document transport direction. The present invention relates to a document feeder in which a document reading position exists between rollers, and more particularly, to prevention of slack of a transferred document at a document reading position and prevention of a change in a transfer speed.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a so-called SPF (Single Pass Feeder) or DSPF (Dup
A document feeder such as a lex single pass feeder) is often used.

In the above-described document transport device, transport drive rollers for transporting the document before and after in the document transport direction in the document transport mechanism are provided, respectively, and a document reading position is provided between these transport drive rollers before and after. I have.

In the one-sided automatic document feed (SPF), originals are taken out one by one from an original placing tray, transported to an original reading position by a PS roller serving as a transport driving roller, and after the original is read, the original is read. The sheet is discharged to a document discharge tray by a transfer roller and a discharge roller which are one transfer drive roller.

In the automatic double-sided document feed (DSPF), similarly, after reading one side of a document conveyed one by one by a PS roller, the document is conveyed by a conveyance roller and a discharge roller, and discharged. When the paper discharge roller rotates in the opposite direction to the discharge, the back side of the document is read and the document is discharged.

In reading an original by the original moving method, it is necessary to bring the original as close as possible to the glass surface at the original reading position in order to ensure the reading of the original.

As a conventional example of a document feeder for bringing a document as close as possible to a glass surface as described above, for example, there is a technique disclosed in Japanese Patent Application Laid-Open No. 62-249848.

According to the technique disclosed in the above publication, as shown in FIG. 12, a document 102 placed on a paper feed tray 101 is transported by a feed roller 103 to a platen glass 104 which is a document reading position. The document 102 is read while moving, and after the reading, the document is discharged to the discharge tray 106 by the transport roller 105.

In this document feeder, air is blown from the automatic document feeder 107 side to the image forming device main body 108 onto the document feed path 109 between the automatic document feeder 107 and the image forming device main body 108. Manuscript 102
Is pressed against the platen glass 104 to obtain stable conveyance. In this publication, FIG.
As shown in FIG. 3, the original 10 is sucked from the image forming apparatus
There is also disclosed a technique for attracting 2 to the platen glass 104 surface.

On the other hand, as another conventional method for stably transporting an original, a PS as a front transport roller is used.
Considering the roller as the main roller for driving,
The driving force is transmitted from the drive source to the PS roller, and the drive is transmitted from the PS roller to the transport roller as the rear transport roller. The idler is inserted into the timing belt between the PS roller and the transport roller to stabilize document transport. For example, in order to eliminate backlash in the drive system and prevent blurring in the transport path system, for example, increase the resistance by contacting the original with a mylar such as a fluoroplastic plastic sheet or a polyethylene terephthalate sheet as a substitute. In some cases, additional materials are added to achieve this.

[0011]

However, in the above-mentioned conventional document feeder, an unnecessarily powerful motor is required due to the fact that additional airflow cannot be controlled or the load on the drive system increases. The situation that needed it was invited. In addition, there is a limit in stabilizing the document conveyance by the additional material, and there is a problem that the conveyance shake generated at the time of reading the document cannot be almost completely prevented.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to be able to drive with a small motor without requiring any additional material, and to almost completely prevent the speed fluctuation of a document. A document that can prevent reading blur at the rear of the document by providing a document conveying device that obtains the original document, and by reducing the drive fluctuation between the rear conveyance roller and the front conveyance roller immediately after the rear end of the document is separated from the front conveyance roller. An object of the present invention is to provide a transport device.

[0013]

According to a first aspect of the present invention, there is provided an original conveying apparatus, in which, in order to solve the above-mentioned problems, conveying driving rollers for conveying an original are provided before and after in the original conveying direction, respectively. In the document feeder in which the document reading position exists between the transport driving rollers, the drive system of the transport driving roller is first transmitted from the driving source to the transport driving roller on the paper discharge side in the document transport direction from the document reading position. Is transmitted to the transport drive roller on the paper feed direction input side of the document reading position, and the peripheral speed of the transport drive roller on the paper discharge direction discharge side of the document read position is greater than the document read position in the document transport direction. It is characterized in that the peripheral speed is higher than the peripheral speed of the conveyance drive roller on the paper input side.

According to the above invention, the original is fed by the rotation of the transport drive roller on the paper entrance side in the original transport direction from the original reading position, and the content of the original is read at the original reading position. Then, the read original is discharged or inverted by the transport drive roller on the discharge side in the document transport direction with respect to the document read position, and is again inverted in the document transport direction with respect to the document read position for double-sided reading. The sheet is passed through a document reading position via a sheet feeding-side conveyance driving roller, and is then discharged by a conveyance driving roller on the sheet discharging side in the document conveying direction from the document reading position.

Here, in the present invention, the drive system of the transport drive roller is such that the drive source is first transmitted to the transport drive roller on the discharge side in the document transport direction from the document read position, and then is transported from the document read position. While being transmitted to the conveyance drive roller on the paper entry side, the peripheral speed of the conveyance drive roller on the paper ejection direction in the document conveyance direction from the document reading position is higher than that of the conveyance drive roller on the paper conveyance direction entry side of the document read position. Greater than peripheral speed.

For this reason, the sheet is engaged with both the transport drive roller on the paper discharge side in the document transport direction with respect to the document read position and the transport drive roller on the input side in the document transport direction with respect to the document read position and passes through the document read position. Since the original to be read is conveyed in a state where the original is pulled by the conveyance drive roller on the paper ejection side relative to the original reading position in the original conveyance direction, the original can be conveyed in a tight state at the original reading position.

When the original is transported and engages with both transport driving rollers, the driving force for transporting the original is moved from the transport driving roller on the paper entrance side in the original transport direction than the original reading position to transport the original from the original reading position. Then, the process proceeds to the transport drive roller on the paper ejection side. For this reason, it is possible to prevent the speed of the document from fluctuating when the trailing edge of the document is displaced from the transport drive roller on the paper transport direction entry side of the document reading position.

As a result, there is provided a document feeder which can be driven by a small motor and does not require any additional material, and which can completely prevent the speed fluctuation of the document. Immediately after moving away from the transport drive roller on the input side in the document transport direction, the drive of the transport drive roller on the discharge side in the document transport direction from the document reading position and the transport drive roller on the input side in the document transport direction from the document read position By reducing the fluctuation, it is possible to provide a document feeder capable of preventing the reading blur at the rear of the document.

According to a second aspect of the present invention, there is provided an original transport apparatus according to the first aspect of the present invention, wherein the transport drive roller is located on a discharge side in the original transport direction relative to the original reading position. The peripheral speed ratio with the transport drive roller on the paper entrance side in the document transport direction from the document reading position is 1.003: 1 to 1
1.03: 1.

According to the above invention, the peripheral speed ratio between the transport drive roller on the paper discharge side in the document transport direction with respect to the document read position and the transport drive roller on the input side in the document transport direction with respect to the document read position is 1. 003: 1 to 1.03: 1.

By setting as described above, it was confirmed by experiments that there was no slack in the original and no blurring occurred.

[0022] Further, by this, tension is applied to the original being conveyed, and a change in the conveying speed before and after the trailing end of the original separates from the conveying drive roller on the input side in the original conveying direction from the original reading position can be tolerated. Can be suppressed.

According to a third aspect of the present invention, in order to solve the above-mentioned problems, in the original document conveying apparatus according to the first or second aspect, the original is placed above the original reading position. A position regulating member having an urging member that presses against the glass surface is provided, and an end of the position regulating member is supported by the document conveying device main body at a position near the document reading position.

That is, at the document reading position, in order to prevent the document from becoming loose, it is preferable to provide a position regulating member having an urging member for pressing the document on the glass surface side of the document reading position.

However, if the position regulating member having the urging member is provided without being supported by any member other than the urging member, the transport driving roller is arranged such that the rear end of the original is closer to the paper feeding direction than the original reading position. When the document exits from the position, the position regulating member loses the upward force due to the document, and the position regulating member is rapidly moved downward by the urging member. For this reason, there is a possibility that the conveyance of the document may be stopped momentarily,
The trailing edge of the document is blurred.

However, according to the present invention, since the end of the position regulating member is supported by the main body of the document feeder, a reaction force acts on the supporting portion, and the downward urging force of the urging member is applied. It can escape to the support.

As a result, it is possible to prevent a sudden change in the downward direction of the position regulating member and to reduce a change in the conveying speed at the rear end of the document.

In the present invention, in particular, the end of the position regulating member is supported by the document feeder main body at a position near the document reading position. In other words, the reaction force of the support portion increases as the distance from the document reading position decreases.

Accordingly, by supporting the end portion of the position regulating member at a position near the document reading position, the reaction force of the supporting portion is increased, and the downward biasing force of the biasing member is applied to this supporting portion by a small amount. Many can be missed.

As a result, a sudden downward shift of the position regulating member can be further prevented, and a change in the conveying speed at the rear end of the document can be further reduced.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problems, in the original transporting apparatus according to the third aspect, an extension portion is provided at an end of the position regulating member, and The extended portion is rotatably supported on the shaft of the transport drive roller on the side closer to the document transport direction than the document reading position, and the extended portion is for discharging the document in the document transport direction than the document reading position. And also serves as a conveyance guide to the side conveyance drive roller.

According to the above invention, the extended portion is provided at the end of the position regulating member, and the extended portion is turned around the axis of the transport drive roller on the paper ejection side in the original transport direction from the original reading position. While being movably supported, the extended portion also serves as a transport guide to a transport drive roller on the discharge side in the document transport direction from the document reading position of the document.

That is, when supporting the end of the position regulating member in the vicinity of the document reading position on the document conveying device main body,
It is desirable to rotatably support the axis of the transport drive roller on the paper discharge side of the document reading position relative to the document reading position because it is a position near the document reading position.

The extended portion of the position regulating member also serves as a conveyance guide from the document reading position to the conveyance driving roller. Therefore, even if the position regulating member moves up and down and rotates about the axis of the transport drive roller, the original is smoothly transported along the extending portion.

As a result, it is possible to prevent the original from blurring due to the vertical movement of the position regulating member.

Further, since this shaft has a width corresponding to the width of the original, it is possible to uniformly support the end of the position regulating member in the width direction of the original. Therefore, the height position of the position regulating member can be uniformly maintained.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In the following embodiments, a case where the document feeder according to the present invention is applied to a copying machine as an image forming apparatus capable of performing both-side printing as well as single-side printing will be exemplified.

As shown in FIG. 2, the document feeder 2 is arranged on a copying machine 1 which is an image forming apparatus main body capable of single-sided printing and double-sided printing. And
The document feeder 2 automatically feeds the document 3 onto a platen glass 27 which is a document reading position 27a of the copying machine 1 which will be described later, so that one-sided or both-sided image information of the document 3 can be read. I have.

The copying machine 1 stores a document reading section 4, an image forming section 5 for printing image information of the document 3 read by the document reading section 4 on a recording sheet 7, and stores the recording sheet 7. And a paper feed unit 6 for sequentially feeding the stored recording paper 7 to the image forming unit 5.

As shown in FIG. 1, the original reading section 4
A lamp reflector assembly 8 for exposing the original 3 conveyed on the platen glass 27 toward the original 3 and a photoelectric conversion element (hereinafter, referred to as “CCD (Charge Coupler)”
d Device) "Reflection mirror 9 for guiding to 11)
a to 9c, an optical lens body 10 for imaging reflected light from the document 3, and the CCD 1 for converting a reflected light image formed by the optical lens body 10 into an electric image signal.
And 1.

The document reading unit 4 converts the image information of the document 3 read as described above into an image signal via an image processing unit (not shown), and converts the image information into a signal as shown by a solid line arrow in FIG. Laser light corresponding to the image signal is irradiated by the semiconductor laser 12 onto the surface of the photoconductor 13 in the image forming section 5 to form an electrostatic latent image on the surface of the photoconductor 13.

The image forming section 5 includes a drum-shaped photosensitive member 13.
A developing unit 14 for visualizing the electrostatic latent image on the photoconductor 13 with toner; a transfer unit 15 for transferring a visible image of the photoconductor 13 with toner to the recording paper 7; A cleaning unit 16 for removing the residual toner, a charging unit 17 for charging the photoconductor 13 to a predetermined potential, and a fixing unit 18 for fixing the toner image transferred to the recording paper 7 by heat and pressure are provided.

An image forming operation in the copying machine 1 having the above configuration will be described.

First, the recording paper 7 is conveyed from the paper supply unit 6 to a recording paper conveyance path 19 passing between the photoconductor 13 and the transfer unit 15.

In the recording paper transport path 19, the recording paper 7
Is once held by the first roller 20. That is, the first roller 20 is used in the image forming section 5 to
In order to accurately transfer the toner image on the surface of the photoconductor 13 to the recording paper 7, the recording paper 7 is moved at a predetermined timing so that the leading end of the image information including the toner image and the leading end of the recording paper 7 are aligned. It is transported to the forming section 5.

The recording paper 7 on which an image has been formed by passing through the recording paper transport path 19 is sent to the paper discharge section 23 by driving the second roller 21 capable of normal and reverse rotation forward.

At this time, if the image forming operation is a one-sided printing process, the recording paper 7 is discharged to the paper discharge unit 23 as it is. However, when the image forming operation is a double-sided printing process, in order to subsequently print on the back surface of the recording paper 7, the second roller 21 is held in a state where the rear end of the recording paper 7 is clamped. The recording paper 7 is sent to the recording paper re-conveying path 24 which forms a loop with the recording paper conveying path 19 by inverting the driving. The recording paper re-conveying path 24
Is provided with a third roller 22 for normally assisting the conveyance of the recording paper 7.

On the other hand, in the copying machine 1, a side cover 25 disposed on the side of the recording paper re-conveying path 24 has an open / close shaft 26.
Is provided rotatably around the fulcrum. When a paper jam or the like occurs in the recording paper transport path 19 or the recording paper re-transport path 24, the side cover 25 can be opened to perform a jam clearance. I can do it.

Next, the document feeder 2 will be described.

As shown in FIG. 1, the document feeder 2 has a PS (Paper Stop) as a feed drive roller on the document feed direction input side of the document tray 31 and the document reading position 27a.
p) a roller 32, a transport roller 42 as a transport drive roller on the paper discharge side in the document transport direction with respect to the document reading position, a paper discharge roller 33, and a paper discharge tray 34; Main transport path 3 for transporting to position 27a
5, and a reverse transport path 36 for feeding the original 3 switched back during double-sided reading to the main transport path 35 again.

A plurality of originals 3 to be read are placed on the original tray 31. The PS roller 32 is
The document 3, which is disposed before the document reading position 27 a in the main transport path 35 and is sent to the main transport path 35, is temporarily stopped here, and then is controlled to a predetermined position to control the reading start position of the document 3. The document 3 is sent to the document reading position 27a at the timing.

That is, when the original 3 conveyed by the original tray 31 or the paper discharge roller 33 which can be rotated forward and backward described later reaches the PS roller 32, the conveyance is temporarily stopped. Thereafter, when the PS roller 32 rotates, the leading end of the document 3 passes through a predetermined distance between the PS roller 32 and the document reading position 27a so that the leading end of the document 3 moves to the document reading position 27a.
Can be set in advance. Thus, the irradiation start is started at the timing when the amount of lamp light of the lamp reflector assembly 8 in the document reading section 4 becomes constant when the document 3 arrives, so that a stable image reading is performed.

As described above, the PS roller 32 is rotated, stopped, and re-rotated in order to output the reference value of the optical system start timing required for stable document reading.

The PS roller 32 has the following other functions.

For example, if the document 3 conveyed to the PS roller 32 has a skew called “diagonal feed”, when the PS roller 32 is temporarily stopped and re-rotated,
The skew is corrected. As a principle of the correction, when the PS roller 32 is temporarily stopped, the original 3 is transferred to the main transport path 35 between the sheet feeding roller 38 and the PS roller 32 shown in FIG.
Alternatively, it stops with slack in the reverse conveyance path 36 and the main conveyance path 35 between the paper discharge roller 33 and the PS roller 32. At this time, the correction is performed based on the elasticity of the paper of the document 3, and the leading end of the document 3 is corrected so as to be perpendicular to the PS roller 32. As a result, in the next step,
When the PS roller 32 rotates, the document 3 is transported in a normal state.

The original 3 to be conveyed is read out at the original reading position 27a, and then discharged through the conveying roller 42 and the discharge roller 33, as described above.

The paper discharge roller 33 is a roller that can be rotated forward and backward, and is used to discharge the read original 3 to the paper discharge tray 34 or to send it to the reverse conveyance path 36. The discharge tray 34 is a discharge destination of the document 3 that has been read.

When reading only one side of the original 3 in the original transport device 2, the original 3 fed from the original tray 31 is picked up by a pickup roller 37 and a paper feed roller 38.
To the main transport path 35, and the original reading position 27a
The document 3 is read. The paper feed roller 38
Is in contact with the paper feed pad 39, and when two or more originals 3 are simultaneously sent out by the pickup roller 37, the conveyance of the lower original 3 is regulated by the paper feed pad 39. 3 can be sent out one by one from the top.

Here, the original reading position 27a is a position where the light of the lamp reflector assembly 8 in the original reading section 4 of the copying machine 1 is irradiated. That is, a platen glass 27 is provided on the upper surface of the document reading unit 4 corresponding to the position of the lamp reflector assembly 8, and when the document 3 moves on the upper surface of the platen glass 27, light is irradiated on the document surface. Then, reading is performed on the lower surface of the document 3.

At the document reading position 27a, a position regulating member 40 is disposed above the platen glass 27. As shown in FIG. 3, the position regulating member 40 has downward convex portions 40a at both ends thereof.
By passing between the platen glass 27 and the position regulating member 40, the optimal positional relationship with the platen glass 27 can be maintained.

Further, as shown in FIG. 1, the position restricting member 40 is provided for the original 3 regardless of its thickness.
So that the distance between the platen glass 27 and the
For example, it is urged downward by a spring 41 such as a conical coil spring or a cylindrical coil spring.

The original 3 thus read is transferred to the discharge tray 3 by the transport roller 42 and the discharge roller 33.
4 is discharged.

When reading both sides of the original 3,
First, the surface of the document 3 is read by the document reading unit 4 on the platen glass 27 by the same operation as the one-side reading described above. The document 3 whose one side has been read is sent to the reversing tray 43 side instead of the sheet discharging tray 34 side. That is,
A switching gate 44 is arranged on the downstream side of the discharge roller 33, and the destination of the document 3 can be switched between the discharge tray 34 and the reversing tray 43 depending on the position of the switching gate 44.

Then, in order to read the back side of the original 3,
In a state where the document 3 is sandwiched between the discharge roller 33 and the discharge driven roller 33a, the discharge roller 33 is driven to rotate in the reverse direction, and the document 3 is sent to the reverse conveyance path 36.

That is, a switching gate 45 is disposed at the junction of the main transport path 35 and the reverse transport path 36 on the upstream side of the paper discharge roller 33, and the rear end of the original 3 sent to the reverse tray 43. At the time when the position exceeds the tip of the switching gate 45, the position of the
Is driven in the reverse direction, the original 3 is sent out to the reverse conveyance path 36.

The original 3 sent out to the reverse transport path 36 is again sent from the main transport path 35 to the original reading position 27a, and is discharged onto the paper discharge tray 34 after the reading of the back surface is completed.

In the above description, the operation of reading the original 3 by the automatic transport mechanism of the original transport apparatus 2 has been described. However, when there is only one original 3 and there is no particular need to use the automatic transport mechanism. Alternatively, when the material of the original 3 is hard and it is difficult to use the automatic transport mechanism, the original 3 can be read without using the automatic transport mechanism.

That is, as shown in FIG.
Is provided so as to be capable of rotating and opening and closing with respect to the copying machine 1,
A table glass 28 corresponding to the maximum size of the readable original 3 is provided on the upper surface of the copying machine 1.
Therefore, when reading the original 3 using the table glass 28, first, after opening the original transport device 2, the original 3 is placed on the table glass 28 with its reading surface down, and thereafter, The document feeder 2 is closed. A document pressing member 46 made of an elastic material 46a and a white film 46b is provided on the lower surface of the document feeder 2. When the document feeder 2 is closed, the document 3 is pressed against the table glass 28. In this state, the original 3 can be read by causing the scanning unit constituted by the lamp reflector assembly 8 and the reflection mirrors 9a to 9c of the original reading section 4 to scan along the original surface.

Next, the characteristic portions of the document feeder 2 of the present embodiment will be described in detail below.

First, as shown in FIG. 1, a PS roller 32 and a transport roller 42 for transporting the document 3 are provided before and after in the document transport direction, respectively. A platen glass 27 serving as a document reading position 27a is provided therebetween.

The driving force of the PS roller 32 and the transport roller 42 is, as shown in FIG.
Performed by 1. That is, the rotational force of the motor 51 is
The power is transmitted to the transport roller 42 via the clutch 52 and via the drive gear 55 and the transport gear 56 shown in FIG. Further, as shown in FIG.
For example, the power is transmitted to the PS roller 32 using a drive transmission mechanism such as the transport pulley 57, the timing belt 58, and the PS pulley 59.

As described above, the main transport path 35 shown in FIG.
The document 3 guided by the paper guides 53 and 54 is transported to the document reading position 27a by the PS roller 32 and the PS driven roller 32a, and then is placed on the discharge tray 34 by the discharge roller 33 via the transport roller 42. In order to read the back side of the original 3, the original 3 is conveyed to a double-sided reading step by the reverse rotation of the discharge roller 33.

Here, in the present embodiment, the transport rollers 4
2 is set slightly higher than the peripheral speed of the PS roller 32. Specifically, as shown in an embodiment described later, the peripheral speed ratio between the transport roller 42 and the PS roller 32 is
1.003: 1 to 1.03: 1. Specifically, in order to set the peripheral speed ratio, the diameter of the transport roller 42 is formed to be slightly larger than the diameter of the PS roller 32.

As described above, when the peripheral speed of the transport roller 42 is
Since the peripheral speed of the roller 32 is set slightly higher, the slack original 3 is gradually tightened. However, at this time, since the tension of the document 3 gradually increases, there is almost no effect on the read image.

That is, as shown in FIG. 5, when the leading end of the document 3 passes through the PS roller 32, the document 3 is conveyed only by the PS roller 32. For this reason, only the PS roller 32 bears the driving force of the document 3, that is, the conveying force. Therefore, at this time, the upper side of the timing belt 58 is slackened.

Next, as shown in FIG. 6, when the document 3 is conveyed while being engaged with both the PS roller 32 and the conveying roller 42, the peripheral speed of the conveying roller 42 is slightly higher. Therefore, the driving force of the document 3 is mainly handled by the transport roller 42, and the document 3 is taut. At this time, the timing belt 58 can be slackened on the lower side opposite to FIG.
The S roller 32 has lost the driving force.

At this time, since the pressing force of the transport driven roller 42a is smaller than the pressing force of the PS driven roller 32a, the transport roller 42 transports the document 3 while slightly slipping. That is, the transport roller 42 transports the document 3 while slipping by the difference between the diameters of the transport roller 42 and the PS roller 32.

At this time, the position restricting member 40 is pressed downward by the spring 41 shown in FIG. 1, and as shown in FIG.
0a ・ 40a, about 0.5m with platen glass 27
m is maintained. For this reason, there is no occurrence of defocusing caused by the document 3 being greatly lifted from the platen glass 27 and exceeding the focal depth for document reading.

During the reading of the document 3, the peripheral speed of the transport roller 42 is slightly higher than that of the PS roller 32, so that the PS roller 32 is gradually dragged by the transport roller 42 and is rotated. become.

At this time, the original 3 is the PS roller 3
Since the document is conveyed without the driving force of 2, the document 3 is not affected at all when the trailing edge of the document 3 passes through the PS roller 32. Therefore, blurring of the document 3 hardly occurs.

For this reason, it is possible to suppress a change in the document feeding speed that causes a change in the reading pitch to be minimized, and to prevent the occurrence of blurring in the read image.

Here, the fluctuation of the reading pitch at which blur occurs means, for example, a reading fluctuation of 0.042 mm corresponding to one pixel at a reading resolution of 600 DPI.

In the above description, the timing belt 58 is exemplified as the drive transmission mechanism from the transport roller 42 to the PS roller 32. However, the present invention is not limited to this, and there is play in the gear even in the case of gear drive. Therefore, the same effect can be expected.

Next, the original 3 having passed through the PS roller 32
Is completely conveyed only by the conveying roller 42. At this time, the difference between the peripheral speeds of the PS roller 32 and the transport roller 42, that is, 1: 1.003 to 1: 1.03,
Although the feeding of the document 3 becomes slightly faster, the change is slight and has little effect on the read image.

Here, in order to explain in more detail the effect of the present embodiment for preventing the occurrence of blurring in the read image, differences from the prior art will be described using comparative examples.

For example, as shown in FIG. 7, in the prior art, the PS roller 32 was considered as a main roller, and a method of applying a driving force to the PS roller 32 first was adopted. In this case, if the timing belt 58 has slack, it is not possible to suppress blurring when the rear end of the document 3 comes off the PS roller 32. Therefore, the idler 60 is pressed against the timing belt 58 to prevent slack. However, the provision of the idler 60 has a disadvantage in that the addition of a drive system is greatly increased.

At first glance, the conveyance of the document 3 in this state seems to be stable, but since the driving force is always applied to both the PS roller 32 and the conveyance roller 42, the rear end of the document 3 When exits the PS roller 32,
The driving force suddenly moves to the transport roller 42.
For this reason, blur occurs.

Next, as another characteristic of the document feeder 2 of the present embodiment, as shown in FIG.
A position restricting member 40 having a spring 41 as an urging member for pressing the original 3 toward the platen glass 27 is provided above the position, and the position restricting member 40 is located near the original reading position 27a. The document is supported by the main body of the document feeder 2. More specifically, as shown in the figure, the position regulating member 40 has an extended portion 40b provided at an end thereof, and the extended portion 40b is turned around a transport roller shaft 42b as a shaft of the transport roller 42. It is movably supported. Also,
The extended portion 40b also serves as a guide for transporting the document 3 to the transport roller 42.

That is, the entire height of the document feeder 2 is regulated by the elastic member 46a of the document pressing member 46 above the table glass 28 used when reading the document 3 in the document fixing system. Because of this, it is not possible to regulate the height stably.

Therefore, the position regulating member 40 is made movable,
A spring 41 is attached to the upper side of the position regulating member 4.
By pressing 0 downward, the reading height of the document is stabilized.

The reason why the extending portion 40b is provided at the end of the position regulating member 40 and is rotatably supported by the conveying roller shaft 42b is as follows.

That is, when the trailing end of the document 3 has passed through the PS roller 32, the position regulating member 40 is attached to the document conveying device 2 at other locations, in addition to the attachment and support of the document conveying device 2 to the main body by the spring 41. Is preferably supported by the main body. The reason is as follows.

First, when the original 3 is transported by the transport roller 42 while being sandwiched between the PS roller 32 and the PS driven roller 32a, the feed speed of the transport roller 42 is high. The force to lift in the direction works. In order to prevent this force, a spring 41 is attached to the position regulating member 40,
The document 3 is pressed downward.

Next, at the moment when the document 3 separates from the PS roller 32 and becomes the conveyance force of the conveyance roller 42 alone, the position regulating member 40 loses the upward force by the document 3 and the document 3 May loosen in the transport path. In order to eliminate this slack, original 3
Is moved downward instantaneously, and the original 3 is placed on the platen glass 27.
Must be in contact with or close to Therefore, the force of the spring 41 is stronger than the force lifted by the document 3, so that the document 3 is not lifted.

The spring 41 is used to move the position regulating member 40 up and down efficiently.
It is mounted just above 0.

Here, if the position regulating member 40 is not supported by the main body of the document conveying device 2 as shown in FIG. When the document 3 comes off the roller 32, the document 3 is released from the state of being stretched by the PS roller 32 and the transport roller 42. At this time, since the position regulating member 40 is suddenly moved downward, a discontinuous portion occurs in the feeding speed of the document 3, which causes rear end blur.

Therefore, in the present embodiment, an extending portion 40b is provided from the end of the position regulating member 40, and the extending portion 40b is provided.
Is rotatably attached to a transport roller shaft 42b of the transport roller 42.

As a result, a reaction force acts on this support portion, and the downward biasing force of the position regulating member 40 by the spring 41 can be released.

As a result, a sudden downward shift of the position regulating member 40 can be prevented, and a change in the transport speed at the rear end of the document can be reduced.

In this embodiment, the extended portion 40b of the position regulating member 40 is connected to the transport roller 42 of the original 3.
It is formed to also serve as a conveyance guide to the device.

That is, with this configuration, as shown in FIG. 9, when the original 3 is engaged with both the PS roller 32 and the transport roller 42, the original 3 is largely displaced upward from the platen glass 27. Occasionally, the original 3 is guided to the transport roller 42 along the extension 40b, as shown by the solid line in FIG. At this time, the platen glass 27
The shape from to the transport roller 42 is substantially the same as when the position regulating member 40 indicated by the two-dot chain line in FIG. That is, there is almost no effect on blur.

In contrast, as shown in FIG. 10, when the position regulating member 40 exists without being supported,
When the position regulating member 40 moves upward, the document 3 is bent at two positions of the position regulating member 40 and the fixed conveyance guide 61.
Therefore, the document 3 is squeezed. If the trailing edge of the document passes through the PS roller 32 in this state, the document 3 behaves in an unpredictable manner and induces blurring.

Similarly, as shown in FIG. 11, when the position regulating member 40 uses the PS roller shaft 32b of the PS roller 32 as a supporting point, the original 3 is positioned as shown in FIG. Since it is bent at two places, that is, the regulating member 40 and the fixed conveyance guide 61, it causes blurring.

As described above, in the document feeder 2 of the present embodiment, the document 3 is fed by the rotation of the PS roller 32 on the paper feed direction entry side from the document read position 27a, and is fed to the document read position 27a. The contents of the original 3 are read. Then, the read original 3 is moved to the original reading position 27.
The sheet is discharged as it is by the transfer roller 42 on the discharge side in the document transfer direction with respect to a or is inverted by the discharge roller 33,
For double-sided reading, the document reading position 2 is again passed through the PS roller 32 on the paper feed direction entry side with respect to the document reading position 27a.
The paper is then discharged by the transport roller 42 and the paper discharge roller 33 on the paper discharge side in the document transport direction from the document reading position 27a.

Here, in the present embodiment, the transport rollers 4
The drive system of the PS roller 2 and the PS roller 32 is first transmitted from the motor 51 to the transport roller 42 on the discharge side in the document transport direction with respect to the document read position 27a, and then the PS is positioned on the input side in the document transport direction with respect to the document read position 27a. While being transmitted to the roller 32,
The peripheral speed of the transport roller 42 is higher than the peripheral speed of the PS roller 32.

Therefore, the transport roller 42 and the PS roller 3
Since the document 3 that is engaged with both the document 2 and the document 3 and passes through the document reading position 27a is conveyed while being pulled by the conveyance roller 42, the document 3 is conveyed in a tensioned state at the document reading position 27a. be able to.

The original 3 is conveyed to the PS roller 32
When the sheet is engaged with both the transport roller 42 and the transport roller 42, the driving force for transporting the document 3 is transferred from the PS roller 32 to the transport roller 42. For this reason, it is possible to prevent the speed of the document 3 from fluctuating when the rear end of the document 3 comes off the PS roller 32.

As a result, there is provided the document feeder 2 which can be driven by the small motor 51 and does not require any additional material, and which can almost completely prevent the speed fluctuation of the document 3. By reducing the drive fluctuation between the transport roller 42 and the PS roller 32 immediately after leaving the roller 32, it is possible to provide the document feeder 2 capable of preventing the reading blur at the rear of the document.

In the document feeder 2 of the present embodiment, the peripheral speed ratio between the feed roller 42 and the PS roller 32 is
1.003: 1 to 1.03: 1.

For this reason, tension is applied to the original 3 being conveyed,
In addition, a change in the transport speed before and after the trailing edge of the document separates from the PS roller 32 can be suppressed within an allowable range.

On the other hand, at the original reading position 27a, in order to prevent the original 3 from being loosened, it is preferable to provide a position regulating member 40 having a spring 41 for pressing the original 3 on the glass surface side of the original reading position.

However, if the position regulating member 40 having the spring 41 is provided without being supported by other than the spring 41, when the rear end of the document 3 passes through the PS roller 32, the position regulating member 40 is The upward force due to the document 3 disappears, and the position regulating member 40 is rapidly moved downward by the spring 41. For this reason, there is a possibility that the conveyance of the document 3 may be stopped momentarily, thereby causing the trailing edge of the document 3 to be blurred.

However, in the present embodiment, since the end of the position regulating member 40 is supported by the main body of the document feeder 2, a reaction force acts on this supporting portion, and the end of the spring 41 is attached to the lower side. Power can escape to this support.

As a result, a sudden downward shift of the position regulating member 40 can be prevented, and a change in the transport speed at the rear end of the document can be reduced.

In this embodiment, the end of the position regulating member 40 is supported by the main body of the document feeder 2 at a position near the document reading position 27a. That is, the reaction force of the support portion increases as the distance from the document reading position 27a decreases.

Therefore, by supporting the end of the position regulating member 40 at a position near the document reading position 27a, the reaction force of the supporting portion is increased, and the downward biasing force of the spring 41 is applied to this supporting portion. Many can be missed.

As a result, a sudden downward shift of the position regulating member 40 can be further prevented, and a change in the transport speed at the rear end of the document can be further reduced.

Further, in the document feeder 2 of the present embodiment, an extended portion 40b is provided at the end of the position regulating member 40, and the extended portion 40b is rotated about the transport roller shaft 42b of the transport roller 42. While being supported as possible, this extension 4
Reference numeral 0b also serves as a conveyance guide for the document 3 to the conveyance roller 42.

That is, when the end of the position regulating member 40 is supported by the main body of the document conveying device 2 in the vicinity of the document reading position 27a, it is rotatably supported by the conveying roller shaft 42b of the conveying roller 42. This is desirable because it is a position near the document reading position 27a.

The extension 40b of the position regulating member 40
Also serves as a conveyance guide from the document reading position 27a to the conveyance roller 42. Therefore, even if the position regulating member 40 moves up and down and rotates around the transport roller shaft 42b,
The document 3 is gently conveyed along the extension portion 40b.

As a result, it is possible to prevent the original 3 from blurring due to the vertical movement of the position regulating member 40.

Since the conveying roller shaft 42b has a width corresponding to the width of the original, the end of the position regulating member 40 can be supported uniformly in the width direction of the original 3. . Therefore, the height position of the position regulating member 40 can be uniformly maintained.

[0123]

As described in the above embodiment, the fact that the peripheral speed of the transport roller 42 is set slightly higher than the peripheral speed of the PS roller 32 prevents the document 3 from loosening at the document reading position 27a. It is preferable to

Therefore, in the present embodiment, an experimental study was made on how much the peripheral speed of the transport roller 42 should be set higher than the peripheral speed of the PS roller 32.

The experiment was conducted with the transport roller 42 and the PS roller 32.
The fluctuation of the original speed, the speed change, and the movement of the original 3 were observed while the peripheral speed ratios of the original 3 were varied.

As a method for making the peripheral speed ratio between the transport roller 42 and the PS roller 32 different, the diameter of each of the transport roller 42 and the PS roller 32 in the conventional document transport device 2 is 15 mm. The peripheral speed ratio of the rollers 42 was changed by sequentially replacing the diameters of the rollers 42 with larger ones.

As a result, Table 1 was obtained.

[0128]

[Table 1]

According to this experiment, in order to tighten the document 3 during conveyance, the diameter of the conveyance roller 42 is
It was found that it was necessary to set the diameter to be at least 0.05 mm larger than the diameter of. At this time, the peripheral speed ratio between the transport roller 42 and the PS roller 32 is 1.003: 1.

On the other hand, if this peripheral speed ratio becomes too large,
When the trailing edge of the document 3 comes off the PS roller 32, the difference in feed speed increases, which affects the read image. At that time, the allowable roller diameter difference is 0.5 mm or less,
As a result, the peripheral speed ratio between the transport roller 42 and the PS roller 32 is 1.03: 1.

In summary, as shown in Table 1, the peripheral speed ratio between the transport roller 42 and the PS roller 32 is 1.00.
It has been found that the ratio of 3: 1 to 1.03: 1 is preferable for trailing edge blur, speed change, and movement of the document 3.

In the case where the peripheral speed ratio is 1: 1, the original 3 may not be loosened and some blur may remain.

[0133]

According to the first aspect of the present invention, there is provided a
As described above, the drive system of the transport drive roller is first transmitted from the drive source to the transport drive roller on the discharge side in the document transport direction with respect to the document reading position, and then is driven on the input side in the document transport direction with respect to the document read position. While being transmitted to the transport drive roller, the peripheral speed of the transport drive roller on the discharge side in the document transport direction from the original reading position is higher than the peripheral speed of the transport drive roller on the input side in the document transport direction than the document read position. It is.

Therefore, the sheet is engaged with both the transport drive roller on the paper discharge side in the document transport direction from the document reading position and the transport drive roller on the paper input side in the document transport direction than the document read position and passes through the document read position. Since the original to be read is conveyed in a state where the original is pulled by the conveyance drive roller on the paper ejection side relative to the original reading position in the original conveyance direction, the original can be conveyed in a tight state at the original reading position.

When the original is transported and engages with both transport driving rollers, the driving force for transporting the original is moved from the transport driving roller on the paper entrance side of the original reading position to the original transport position than the original reading position. Then, the process proceeds to the transport drive roller on the paper ejection side. For this reason, it is possible to prevent the speed of the document from fluctuating when the trailing edge of the document is displaced from the transport drive roller on the paper transport direction entry side of the document reading position.

As a result, there is provided a document feeder which can be driven by a small motor and does not require any additional material, and which can completely completely prevent the fluctuation of the speed of the document. Immediately after moving away from the transport drive roller on the input side in the document transport direction, the drive of the transport drive roller on the discharge side in the document transport direction with respect to the document reading position and the transport drive roller on the input side in the document transport direction with respect to the document read position By reducing the fluctuation, it is possible to provide a document feeder capable of preventing the reading blur at the rear of the document.

According to a second aspect of the present invention, as described above, in the original transport apparatus according to the first aspect, the transport drive roller and the original reading position on the discharge side in the original transport direction with respect to the original reading position. The peripheral speed ratio with the transport driving roller on the paper input side in the document transport direction is 1.003: 1 to 1.03: 1.
It is.

Therefore, by setting in this way, it was confirmed by experiments that there was no slack in the document and no blurring occurred.

[0139] Thus, tension is applied to the original being conveyed, and a change in the conveyance speed before and after the rear end of the original separates from the conveyance drive roller on the input side in the original conveyance direction from the original reading position can be tolerated. This has the effect of being able to be suppressed.

According to a third aspect of the present invention, as described above, in the original document conveying apparatus according to the first or second aspect, the original is placed above the original reading position on the glass surface side of the original reading position. A position regulating member having an urging member for holding the document is provided, and an end of the position regulating member is supported by the document conveying apparatus main body at a position near the document reading position.

Therefore, since the end of the position regulating member is supported by the main body of the document feeder, a reaction force acts on this supporting portion, and the downward urging force of the urging member is applied to this supporting portion. You can escape.

As a result, it is possible to prevent an abrupt shift in the downward direction of the position regulating member and to reduce the change in the transport speed of the rear end of the document.

Further, according to the present invention, particularly, since the end of the position regulating member is supported by the document conveying device main body at a position near the document reading position, the reaction force of the supporting portion is increased, and Can be released to the support portion as much as possible.

As a result, it is possible to prevent a sudden change in the downward direction of the position regulating member, and to further reduce the change in the conveying speed at the rear end of the document.

According to a fourth aspect of the present invention, as described above, in the original transporting apparatus according to the third aspect, an extended portion is provided at an end of the position regulating member, and the extended portion is provided. The extension portion is rotatably supported by a shaft of a transport drive roller on the paper discharge side in the document transport direction with respect to the document reading position, and the extended portion is a transport drive on the paper transport direction in the document transport direction with respect to the document read position. It also serves as a transport guide to the rollers.

Therefore, the position regulating member moves up and down,
Even if the document is rotated about the axis of the transport driving roller, the document is smoothly transported along the extending portion.

As a result, it is possible to prevent the original from being shaken due to the vertical movement of the position regulating member.

Further, since this shaft has a width corresponding to the width of the original, it can be uniformly supported in the width direction of the original when supporting the end of the position regulating member. Therefore, there is an effect that the height position of the position regulating member can be uniformly maintained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a document feeder according to the present invention.

FIG. 2 is an overall configuration diagram showing a copying machine provided with the document conveying device.

FIG. 3 is a configuration diagram illustrating a position regulating member in the document transport device.

FIG. 4 is an explanatory diagram showing a state in which the document feeder is opened to a copying machine.

FIG. 5 is an explanatory diagram showing a state in which a document is conveyed only by PS rollers in the document conveyance device.

FIG. 6 is an explanatory diagram showing a state in which a document is conveyed while being engaged with a PS roller and a conveyance roller in the document conveyance device.

FIG. 7 is an explanatory diagram showing a state in which a document is conveyed by engaging with a PS roller and a conveyance roller in a document conveyance device in which a drive system is first transmitted to a PS roller.

FIG. 8 is an explanatory diagram showing a state in which the position regulating member of the document feeder is not supported.

FIG. 9 is an explanatory diagram showing a state of conveying a document when the position regulating member moves up and down in the document conveying apparatus.

FIG. 10 is an explanatory diagram illustrating a document conveyance state when the position regulating member moves up and down in the document conveying device in which the position regulating member is not supported.

FIG. 11 is an explanatory diagram showing a document conveyance state when the position regulating member moves up and down in a case where the position regulating member of the document conveying device is supported by a PS roller shaft.

FIG. 12 is a configuration diagram showing a conventional document feeder.

FIG. 13 is a configuration diagram illustrating another conventional document feeder.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Copier 2 Document feeder 3 Document 8 Lamp reflector assembly 27 Platen glass (glass) 27a Document reading position 28 Table glass 32 PS roller (Conveyance driving roller on the paper feeding direction input side from document reading position) 33 Discharge roller Reference numeral 40 Position regulating member 40b Extension 41 Spring (biasing member) 42 Conveyance roller (conveyance drive roller on the paper discharge side in the document conveyance direction from the document reading position) 42b Transport roller shaft (axis) 51 Motor (drive source)

Claims (4)

[Claims] A drive system for driving the transport drive rollers in a document transport apparatus in which transport drive rollers for transporting a document are provided before and after in the document transport direction, and a document reading position exists between the transport drive rollers before and after the transport drive rollers. Is transmitted from a drive source to a transport drive roller on the paper discharge side of the document reading position with respect to the original reading position, and then transmitted to a transport drive roller on the input side of the document transport direction with respect to the document read position. A document feeder, wherein a peripheral speed of a transport drive roller on a discharge side in a document transport direction from a reading position is higher than a peripheral speed of a transport drive roller on a feed side in a document transport direction than the document read position. 2. A peripheral speed ratio between a transport drive roller on the paper discharge side of the original reading position and a transport drive roller on the input side in the document transport direction relative to the original read position is 1.003: 1.
2. The document feeder according to claim 1, wherein the ratio is 1.03 to 1.03: 1. 3. A position regulating member having an urging member for pressing the document toward the glass surface of the document reading position is provided above the document reading position, and an end of the position regulating member is positioned at the document reading position. 3. The document transport device according to claim 1, wherein the document transport device is supported by the document transport device main body at a position near the document transport device. 4. An extended portion is provided at an end of the position regulating member, and the extended portion is rotatably supported by a shaft of a transport drive roller on the paper discharge side in the document transport direction from the document reading position. 4. The document conveying device according to claim 3, wherein the extension portion also serves as a conveyance guide to a conveyance driving roller on a discharge side in a document conveyance direction from the document reading position of the document.