JP2011207561A - Roller contacting-separating mechanism and automatic document carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roller contacting-separating mechanism which provides a separation quantity between a driven roller and a driving roller capable of releasing sheet carrying force, when separating the driven roller from the driving roller, without requiring to particularly enlarge the mechanism.SOLUTION: This roller contacting-separating mechanism is provided for bringing or separating the driven roller Kr into pressure contact with or from the driving roller (a discharge roller Dr) for carrying a sheet (a document). The roller contacting-separating mechanism 100 includes a driving lever L1 having one end part connected to a plunger PL of a solenoid SOL and a driven lever L2 driven by slidingly contacting with the driving lever L1, that is, the driven lever L2 for bringing about contacting-separating operation to the discharge roller Dr of the driven roller Kr, wherein a contact point between the driving lever L1 and the driven lever L2 moves to a part Q on the driven lever rocking fulcrum L2s side from part P on the driven lever tip side in response to the lever rotational movement, and thus, a desired separate distance can be provided between both rollers Dr and Kr without enlarging the solenoid.

Description

  The present invention includes a driving roller, a driven roller facing the driving roller, and a roller contact / separation mechanism that presses or separates the driven roller with respect to the driving roller. The roller contact / separation mechanism presses the driven roller against the driving roller. In this state, the roller contact / separation mechanism and the roller contact / separation mechanism are used in the sheet transport mechanism that can transport the sheet between the driving roller and the driven roller with the sheet sandwiched between them and release the sheet transport force by separating the driven roller from the driving roller. The present invention relates to an automatic document feeder.

  The sheet conveying mechanism and the roller contacting / separating mechanism are used in various fields. For example, it is used in a document conveying device mounted on an image reading device.

Accordingly, let us look at an automatic document feeder that constitutes an image reading apparatus of the image forming apparatus.
FIG. 5 shows an example 10 of an image forming apparatus. The image forming apparatus 10 includes a printer portion PR and an image reading device 9 mounted thereon. The image forming apparatus 10 is a so-called multifunction machine that can be used as a copying machine, a printer, a facsimile machine, or the like.
The image reading device 9 includes an image reading device main body 900 and an automatic document feeder 901 mounted thereon. FIG. 6 is a perspective view of the automatic document feeder 901. FIG. 7 is an enlarged view of a part of the automatic document feeder 901.

The printer portion PR is not limited thereto, but here, based on the image information read from the document by the image reading device 9, the image information transmitted from an external computer, a facsimile machine, etc., the recording sheet is electrophotographic. In addition, a toner image can be formed.
The printer portion PR is not described in detail, but can form a monochrome toner image on recording paper by electrophotography. Generally speaking, the printer portion PR may be capable of forming a color image, or may be capable of forming an image with, for example, ink other than electrophotography.

  The image reading apparatus main body 900 constituting the image reading apparatus 9 is already known per se, and the automatic original conveying apparatus 901 conveys the original along the original table glass g1 to thereby store the original. An image can be shot, or an original can be placed on a large platen glass g2 and the original image can be read.

  The automatic document feeder 901 is hinged to the image reading apparatus main body 900 so as to be openable and closable, and also functions as a cover that can open and close the surface on which the document table glasses g1 and g2 are provided.

The automatic document feeder 901 is configured to convey a document from the document placing tray 91, the document discharge tray 92 below the document placement tray 91, and the document placing tray 91 to the document discharge tray 92 through the document reading unit 94. It has a path 93.
As shown in FIG. 6, the front side edge portion of the document placing tray 91 is lacking as indicated by reference numeral 913, leaving a part 912 so that the document can be easily taken out from the lower document discharge tray 92.

The following rollers are sequentially arranged along the document conveyance path 93. That is,
Rollers Pr and R1 for taking a document on the document placing tray 91;
A registration roller R2 for correcting the skew of the document captured by the rollers Pr and R1,
A document reading roller R3 and a document reading roller R4 disposed on both sides of the document reading unit 94 for transporting the document supplied from the registration roller R2 through the document reading unit 94;
And a discharge roller Dr.

  The document reading unit 94 positions the document being transported so that the document is transported along the document panning glass plate g1 of the image reading apparatus main body 900.

  Of the rollers for taking in the original on the original placing tray 91, the roller Pr is a pickup roller. The pick-up roller Pr picks up the original one by one when the original placed on the tray 91 comes into contact with the roller Pr when the tray front end 911 is lifted by an elevating drive unit (not shown). Pass to R1.

  The driven rollers r1, r2, r3 and r4 are pressed against the rollers R1, R2, R3 and R4 by springs (not shown), respectively. A driven roller Kr is pressed against the discharge roller Dr so as to be separated by a spring Sp.

  The pickup roller Pr, the supply roller R1, and the registration roller R2 can be rotationally driven so that the document is conveyed to the pre-document reading roller R3 by the first roller driving mechanism D1 including the motor M1. However, the registration roller R2 starts to rotate after the leading edge of the document supplied by the supply roller R1 collides with the registration roller R2 and the leading edge of the document is slackened. Thereby, the skew of the original is corrected.

  The original document reading roller R3, the original document reading roller R4, and the discharge roller Dr can be driven to rotate forward all at once so that the original is discharged to the discharge tray 92 by the second roller driving mechanism D2 including the motor M2. Further, the discharge roller Dr can be reversed. When the discharge roller Dr is reversed, the roller R3 before document reading and the roller R4 after document reading are also reversed. The second roller drive mechanism D2 is configured to rotate the rollers R3, R4, and Dr all at once in order to simplify the mechanism, as is common in conventional automatic document feeders.

  The automatic document feeder 901 further includes a circulation conveyance path 95 extending from a portion near the discharge roller Dr to a registration roller R2 in a portion of the document conveyance path from the roller R4 to the discharge roller Dr after reading the document.

  As shown in FIG. 8, the discharge roller Dr discharges the document Sh1 passing through the roller R4 after reading the document to the discharge tray 92 by normal rotation. In the document double-sided reading mode for reading images on both sides of the document, As shown in FIG. 9, after the original is read, the original Sh1 passing through the roller R4 is discharged to the discharge tray 92 leaving a part, and then reversely rotated to switch back the original. Transport to R2.

  At this time, the flexible film valve f <b> 2 is provided at a portion branched from the normal document conveyance path 93 and the circulation conveyance path 95 when viewed from the discharge roller Dr side so that the document is smoothly switched back to the circulation conveyance path 95. Is cantilevered.

  The flexible film valve f2 closes the portion of the document conveying path 93 that faces the circulation conveyance path 95 when no external force is applied, and the document coming from the roller R4 after reading the document pushes up the flexible film valve f2. It can go to the discharge roller Dr. The document that is switched back by the reverse rotation of the discharge roller Dr can pass over the closed flexible film valve f <b> 2 toward the circulation conveyance path 95.

  A flexible film valve f1 is also provided at the outlet from the circulation conveyance path 95 toward the registration roller R2. The flexible film valve f1 closes the outlet of the circulation conveyance path 95 when receiving no external force. The document from the rollers Pr and R1 to the registration roller R2 can pass through the closed valve f1, and the document from the circulation conveyance path 95 to the registration roller R2 can go to the registration roller R2 while pushing up the valve f1. .

The document that is switched back by the reverse rotation of the discharge roller Dr and re-supplied to the registration roller R2 is again passed through the image reading unit 94 in a state of being reversed, and is discharged to the discharge tray 92.
At this time, after the leading edge of the original that has been turned upside down passes through the registration roller R2, before the original reading roller R3, the original reading roller R3 and the original reading roller R4 are switched from reverse rotation to normal rotation. . At this time, since the discharge roller Dr is also switched from reverse rotation to normal rotation, if the trailing edge of the document to be switched back has not yet come out of the discharge roller Dr, the document conveyance is hindered.

Therefore, the automatic document feeder 901 is provided with a roller contact / separation mechanism 100 ′ as shown in FIGS. 10 and 11, for example.
As a roller contact / separation mechanism for the document discharge roller portion in the document transport device, Japanese Patent No. 4072516 discloses a mechanism for separating the discharge roller. On the other hand, the illustrated roller contact / separation mechanism 100 is a driven roller. Kr is separated from the driving roller (discharge roller Dr) at a fixed position, and the structure is simple.

  In the illustrated roller contact / separation mechanism 100, one end portion of a lever L ′ whose both end portions can be swung with a middle portion as a fulcrum Ls is rotatably connected to a plunger PL ′ of a plunger type solenoid SOL ′. The driven roller Kr is rotatably supported at the other end. A spring Sp for pressing the driven roller Kr against the discharge roller Dr pushes the other end of the lever L ′ upward from below.

FIG. 10 shows a state in which the solenoid is not energized. The solenoid plunger PL ′ protrudes downward, and the driven roller Kr is elastically pushed up by the spring Sp and presses against the discharge roller Dr.
FIG. 11 shows a state in which the solenoid is not energized, the solenoid plunger PL ′ is in a state of being driven backward, and the driven roller Kr is separated from the discharge roller Dr against the spring Sp.

Japanese Patent No. 4072516

  The plunger type solenoid has characteristics as shown in FIG. That is, the plunger pop-out amount in the initial state where the plunger pop-out amount when the solenoid is not energized is S0, the solenoid attraction force obtained by energizing the solenoid at that time is F0, and the plunger pop-out amount during solenoid attraction is S1. Assuming that the solenoid suction force is F1, as shown in FIG. 12, the solenoid suction force increases as the plunger stroke decreases (the pop-out amount decreases), and the solenoid suction force increases as the plunger is sucked.

  In the roller contact / separation mechanism 100 ′, when the lever ratio (L2 ′ / L1 ′) is increased, a large separation amount between both rollers can be obtained with a small plunger stroke, but the suction force of the solenoid must be increased. Accordingly, the solenoid becomes larger and more expensive. On the other hand, if the lever ratio (L2 ′ / L1 ′) is decreased, the suction force of the solenoid may be small. However, to obtain a large separation between both rollers, the plunger stroke must be increased, and the larger roller contact is required. A space for installing the separation mechanism is required, which leads to an increase in the size of the document conveying device.

  Accordingly, the present invention includes a drive roller, a driven roller facing the drive roller, and a roller contact / separation mechanism that presses or separates the driven roller from the drive roller, and the roller contact / separation mechanism turns the driven roller into the drive roller. A roller contacting / separating mechanism in a sheet conveying mechanism that can convey a sheet while sandwiching the sheet between the driving roller and the driven roller in a pressure contact state, and can release the sheet conveying force by separating the driven roller from the driving roller. It is a first object to provide a roller contact / separation mechanism that can obtain a separation amount between both rollers that can release the sheet conveying force when separating from the driving roller, and that does not need to be particularly large.

The present invention also provides
A document tray,
The document exit tray,
A document transport path for guiding the document from the document placement tray to the document discharge tray through the document reading unit;
A roller for taking in the original on the original tray;
A registration roller for correcting the skew of the document captured by the roller;
A document reading roller and a document reading roller disposed on both sides of the document reading unit for conveying the document supplied from the registration roller through the document reading unit;
A discharge roller that can discharge a document passing through the roller after reading the document to the discharge tray, and can switch back the document discharged to the discharge tray with reverse rotation, and a driven roller that is paired with the discharge roller; ,
A circulation conveyance path that guides a document that is discharged to a discharge tray with a part of the discharge roller and switched back by reverse rotation of the discharge roller to the registration roller;
A first roller driving mechanism for driving the roller and the registration roller for taking in the document on the document placing tray to rotate forward for document feeding;
To drive the roller before document reading, the roller after document reading, and the discharge roller in conjunction with normal rotation for feeding the document, or to drive in reverse rotation to circulate and convey the document from the discharge tray to the registration roller for reading both sides of the document. A second roller drive mechanism;
An automatic document feeder comprising a roller contact / separation mechanism that separates a driven roller that makes a pair with the discharge roller from the discharge roller,
When the driven roller is separated from the discharge roller by the roller contact / separation mechanism in the document double-sided reading mode, it is possible to obtain a separation amount between both rollers capable of releasing the document conveying force, and the roller contact / separation mechanism portion needs to be particularly large. A second problem is to provide an automatic document feeder that can execute the document double-sided reading mode as much as the entire apparatus and that does not cause a particularly large size.

In order to solve the first problem, the present invention provides:
A driving roller, a driven roller facing the driving roller, and a roller contacting / separating mechanism that presses or separates the driven roller with respect to the driving roller, and the driven roller is pressed against the driving roller by the roller contacting / separating mechanism. A roller contacting / separating mechanism in a sheet conveying mechanism that can convey the sheet between the driving roller and the driven roller and can release the sheet conveying force by separating the driven roller from the driving roller;
A solenoid having a reciprocable plunger, a drive lever, a driven lever, a driven roller support arm that rotatably supports the driven roller, and a spring that presses the driven roller against the drive roller when the solenoid is not energized. In addition, the drive lever can swing around the first fulcrum set in the middle of the lever, and the driven lever and the roller support arm are fixedly supported on the same support shaft and swing around the second fulcrum on the same support shaft. One end of the drive lever is rotatably connected to the plunger of the solenoid and the other end abuts on the free end of the driven lever. The drive lever is placed in a protruding state and the other end of the drive lever and the free end of the driven lever are in pressure contact with the drive roller. When the solenoid is energized, the plunger moves backward to the solenoid body, the drive lever swings due to the backward movement of the plunger, and the other end of the drive lever presses the free end of the driven lever. Meanwhile, the mutual contact portion between the other end of the drive lever and the free end of the driven lever moves in a direction approaching the second fulcrum from the first mutual contact portion, and when the plunger is retracted, the driven roller is set at a predetermined distance from the drive roller. Provided is a roller contact / separation mechanism that contacts at a second mutual contact site for placing in a separated state.

In order to solve the second problem, the present invention
A document tray,
The document exit tray,
A document transport path for guiding the document from the document placement tray to the document discharge tray through the document reading unit;
A roller for taking in the original on the original tray;
A registration roller for correcting the skew of the document captured by the roller;
A document reading roller and a document reading roller disposed on both sides of the document reading unit for conveying the document supplied from the registration roller through the document reading unit;
A discharge roller that can discharge a document passing through the roller after reading the document to the discharge tray, and can switch back the document discharged to the discharge tray with reverse rotation, and a driven roller that is paired with the discharge roller; ,
A circulation conveyance path that guides a document that is discharged to a discharge tray with a part of the discharge roller and switched back by reverse rotation of the discharge roller to the registration roller;
A first roller driving mechanism for driving the roller and the registration roller for taking in the document on the document placing tray to rotate forward for document feeding;
To drive the roller before document reading, the roller after document reading, and the discharge roller in conjunction with normal rotation for feeding the document, or to drive in reverse rotation to circulate and convey the document from the discharge tray to the registration roller for reading both sides of the document. A second roller drive mechanism;
An automatic document feeder provided with a roller contact / separation mechanism for separating a driven roller paired with the discharge roller from the discharge roller;
Provided is an automatic document feeder in which a roller contact / separation mechanism according to the present invention is employed as a roller contact / separation mechanism.

  According to the roller contact / separation mechanism according to the present invention, when the solenoid is energized and the plunger starts to retract from the protruding state, the drive lever swings around the first fulcrum in conjunction with the retracting operation of the plunger. The driven lever free end is pushed by the other end of the drive lever, the driven lever swings around the second fulcrum, and the driven roller support arm that interlocks with the driven lever via the support shaft of the driven lever is also second. Swing about the fulcrum and thus the driven roller begins to separate from the drive roller.

  In this way, when the solenoid is energized and the plunger starts to retract from the protruding state, the suction force of the solenoid is small, but the driven lever is relatively far from the second fulcrum that is the fulcrum of the driven lever. Since it is started to be pushed by the drive lever at the site, the driven lever, and therefore the driven roller support arm interlocked therewith, can be started to swing against the spring force even if the suction force of the solenoid is still small.

When the plunger is further retracted in this manner and the drive lever further swings the driven lever, the mutual contact portion of both levers gradually approaches the second fulcrum, and even with a small retraction operation of the plunger, the small retraction operation can be performed. The driven lever, and hence the driven roller support arm, swings greatly, and the driven roller can be separated from the drive roller by a predetermined distance.
An example of the predetermined separation distance is a separation distance at which the sheet conveying force can be safely and reliably released.

  In this way, when the mutual contact portion of both levers approaches the second fulcrum, which is the fulcrum of the driven lever, a large force is required to swing the driven lever. Since the solenoid's attractive force is large, the operation of each part is not hindered.

When the plunger is retracted, both levers come into contact with each other at a second mutual contact portion for placing the driven roller at a predetermined distance from the driving roller.
When the solenoid is switched from the energized state to the non-energized state, the driven roller is pressed against the discharge roller by a spring force, and the plunger, both levers, the driven roller support arm, etc. return to the state before the energization of the solenoid.

  Thus, according to the roller contact / separation mechanism according to the present invention, when the driven roller is separated from the driving roller, a predetermined separation amount between both rollers for releasing the sheet conveying force can be obtained, and the solenoid is enlarged. It is not necessary to enlarge the whole by doing so.

  In the automatic document feeder according to the present invention, the roller contact / separation mechanism according to the present invention is adopted as a mechanism for contacting and separating the driven roller that is paired with the discharge roller. When separating the driven roller from the discharge roller by the separation mechanism, it is possible to obtain a separation amount between both rollers that can release the document conveying force, and the roller contacting / separating mechanism portion does not need to be particularly large, and the entire document conveying apparatus. Even so, the document double-sided reading mode can be executed safely and reliably, and there is no particular increase in size.

  In the roller contact / separation mechanism according to the present invention, the other end of the drive lever at the free end of the driven lever is used to smooth the mutual contact swing between the drive lever and the driven lever and to make the moving distance of the mutual contact portion of both levers as large as possible. The surface that is in sliding contact with the portion is a surface having a circular cross section perpendicular to the support shaft on which the driven lever is fixedly supported, and is in sliding contact with the free end of the driven lever at the other end of the drive roller. The surface has a cross-sectional shape perpendicular to the spindle on which the driven lever is fixedly supported, and a sliding contact surface of the driven lever free end with the other end of the drive lever and a slidable arcuate surface can do.

  For example, the surface of the driven lever free end that is in sliding contact with the other end of the drive lever has a concave arc-shaped surface perpendicular to the spindle on which the driven lever is fixedly supported, and the other end of the drive roller. The surface which is in sliding contact with the free end of the driven lever of the portion can be a surface having a convex arc shape in a cross section perpendicular to the spindle on which the driven lever is fixedly supported.

  The roller contact / separation mechanism of the automatic document feeder according to the present invention allows the leading edge of the document to be circulated and conveyed to the registration roller by the switchback operation by the reverse rotation of the discharge roller for reading both sides of the document before the document is read after passing the registration roller. When the second roller driving mechanism switches the roller before reading the document, the roller after reading the document, and the discharging roller from reverse rotation to normal rotation before reaching the roller, the driven roller that makes a pair with the discharging roller is separated from the discharging roller. Can be.

  As described above, according to the present invention, the driving roller, the driven roller facing the driving roller, and the roller contacting / separating mechanism for pressing or separating the driven roller from the driving roller are driven by the roller contacting / separating mechanism. The roller contacting / separating mechanism in the sheet conveying mechanism that can convey the sheet while sandwiching the sheet between the driving roller and the driven roller with the roller pressed against the driving roller, and can release the sheet conveying force by separating the driven roller from the driving roller. Thus, when the driven roller is separated from the driving roller, it is possible to obtain a separation amount between the two rollers that can release the sheet conveying force, and to provide a roller contact / separation mechanism that does not need to be particularly large.

Also according to the present invention,
A document tray,
The document exit tray,
A document transport path for guiding the document from the document placement tray to the document discharge tray through the document reading unit;
A roller for taking in the original on the original tray;
A registration roller for correcting the skew of the document captured by the roller;
A document reading roller and a document reading roller disposed on both sides of the document reading unit for conveying the document supplied from the registration roller through the document reading unit;
A discharge roller that can discharge a document passing through the roller after reading the document to the discharge tray, and can switch back the document discharged to the discharge tray with reverse rotation, and a driven roller that is paired with the discharge roller; ,
A circulation conveyance path that guides a document that is discharged to a discharge tray with a part of the discharge roller and switched back by reverse rotation of the discharge roller to the registration roller;
A first roller driving mechanism for driving the roller and the registration roller for taking in the document on the document placing tray to rotate forward for document feeding;
To drive the roller before document reading, the roller after document reading, and the discharge roller in conjunction with normal rotation for feeding the document, or to drive in reverse rotation to circulate and convey the document from the discharge tray to the registration roller for reading both sides of the document. A second roller drive mechanism;
An automatic document feeder comprising a roller contact / separation mechanism that separates a driven roller that makes a pair with the discharge roller from the discharge roller,
When the driven roller is separated from the discharge roller by the roller contact / separation mechanism in the document double-sided reading mode, it is possible to obtain a separation amount between both rollers capable of releasing the document conveying force, and the roller contact / separation mechanism portion needs to be particularly large. Thus, the automatic document conveying apparatus can be provided which can execute the document double-sided reading mode as much as the entire apparatus and which does not cause a particularly large size.

It is a perspective view of an example of the roller contacting / separating mechanism according to the present invention. It is a figure which shows the state at the time of solenoid non-energization of the principal part of the roller contact / separation mechanism shown in FIG. It is a figure which shows the state at the time of solenoid energization of the principal part of the roller contact / separation mechanism shown in FIG. It is a figure which shows the improvement in parts other than the roller contact / separation mechanism in an automatic document feeder. 1 is a diagram illustrating an example of an image forming apparatus including an image reading apparatus including an automatic document feeder. 1 is a perspective view of an automatic document feeder. FIG. 3 is an enlarged view of a main part of an automatic document feeder. FIG. 4 is a diagram illustrating a state of document conveyance when a single-sided document is read by an automatic document conveyance device. FIG. 6 is a diagram illustrating a state of document conveyance when a document is read on both sides by an automatic document conveyance device. It is a figure which shows the mode at the time of solenoid non-energization in the prior art example of a roller contacting / separating mechanism. It is a figure which shows the mode at the time of solenoid energization in the roller contacting / separating mechanism shown in FIG. It is a figure which shows the relationship between the plunger stroke of a plunger type solenoid, and solenoid attraction force.

  1 to 3, the roller contact / separation mechanism according to the present invention includes a discharge roller Dr that is rotated and driven by the automatic document feeder 901 shown in FIGS. 1 to 5 and a driven roller Kr that is paired with the discharge roller Dr. The case where it uses for contact / separation is demonstrated.

  A roller contact / separation mechanism 100 shown in FIGS. 1 to 3 is a roller contact / separation mechanism that causes the driven roller Kr in the automatic document feeder 901 to be in pressure contact with or separated from the discharge roller Dr that is rotationally driven at a fixed position. With the roller contact / separation mechanism 100 in contact with the driven roller Kr against the discharge roller Dr, the discharge roller Dr is rotated forward or reverse, and the sheet-like document is sandwiched between the rollers Dr and Kr and conveyed to the discharge tray 92. Can be switched back to the registration roller R2 (during reverse rotation).

  The roller contact / separation mechanism 100 is switched back by the discharge roller Dr that is reversed in the document double-side reading mode, and after the leading edge of the document conveyed to the registration roller R2 through the circulation conveyance path 95 passes the registration roller R2, the roller before document reading Prior to switching from the reverse rotation drive to the normal rotation drive before the document reading roller R3, the document reading roller R4 and the discharge roller Dr before reaching R3, the driven roller Kr is separated from the discharge roller Dr, which hinders the circulation of the document. So that there is no.

  As shown in FIG. 1, the roller contact / separation mechanism 100 includes a solenoid SOL having a reciprocable plunger PL, a drive lever L1, a driven lever L2, and a driven roller support arm Am that rotatably supports the driven roller Kr. And a spring Sp for pressing the driven roller Kr against the discharge roller Dr when the solenoid is not energized.

  The spring Sp may be provided in any part as long as the driven roller Kr is pressed against the discharge roller Dr when the solenoid is not energized, and various springs such as a tension coil spring, a compression coil spring, and a leaf spring are employed. However, here, a compression coil spring is employed that lifts the roller support arm Am so that the driven roller Kr is pressed against the discharge roller Dr.

  The drive lever L1 can swing around a first fulcrum L1s set in the middle part of the lever by rotatably supporting the middle part of the lever by a bearing member (not shown) provided in the document conveying device 901. The driven lever L2 and the roller support arm Am are fixedly supported on the same support shaft s1, and the support shaft s1 is rotatably supported by a bearing member (not shown) provided in the document conveying device 901. It can swing around the set second fulcrum L2s.

  One end of the drive lever L1 is rotatably connected to the plunger PL of the solenoid SOL, and the other end is in contact with the upper surface of the free end of the driven lever L2. When the solenoid is not energized, as shown in FIG. 2, the plunger PL is protruded from the solenoid body, and the other end of the drive lever and the free end of the driven lever lift the driven roller Kr to the discharge roller Dr by the spring Sp. Contact is made at a first mutual contact site (first mutual contact position) P for placing in pressure contact. The distance between the part P and the second fulcrum L2s is X.

  When the solenoid is energized, the plunger PL moves backward to the solenoid body as shown in FIG. 3, and the drive lever L1 swings clockwise in the drawing as the plunger moves backward, and the other end of the drive lever presses the free end of the driven lever. However, the other end portion of the drive lever and the upper surface of the free lever free end portion slide with each other, and the mutual contact portion of both levers moves from the first mutual contact portion P toward the second fulcrum L2s. When the plunger PL is retracted, the second mutual contact portion (second mutual contact) for placing the driven roller Kr away from the discharge roller Dr by a predetermined distance (here, a distance where the document conveying force can be safely and reliably released) is separated. Position) Touch at Q. The distance between the part Q and the second fulcrum L2s is Y (<the distance X).

  The surface Sf2 that is in sliding contact with the other end of the drive lever L1 at the free end of the driven lever L2 is a surface having a concave arc shape in cross section perpendicular to the support shaft s1 on which the driven lever L2 is fixedly supported. The surface Sf1 that is in sliding contact with the free end of the driven lever L2 at the other end of the drive lever L1 is a surface having a convex arc shape in cross section perpendicular to the support shaft s1 on which the driven lever L2 is fixedly supported. The radius of curvature of the convex arc that provides the surface Sf1 is smaller than the radius of curvature of the concave arc that provides the surface Sf2. By adopting an arc-shaped surface in this way, the mutual contact swing of the drive lever L1 and the driven lever L2 is smoothed, and the moving distance of the mutual contact portion of both levers can be made as large as possible.

  According to the roller contact / separation mechanism 100 described above, when the solenoid SOL is energized and the plunger PL starts to retract from the protruding state, the drive lever L1 swings around the first fulcrum L1s in conjunction with the retracting operation of the plunger PL. Then, the free end of the driven lever L2 is pushed by the other end of the swinging drive lever L1, the driven lever L2 swings about the second fulcrum L2s, and further driven via the support shaft s1 of the driven lever L2. The driven roller support arm Am interlocked with the lever L2 also swings about the second fulcrum L2s, and thus the driven roller Kr starts to separate from the discharge roller Dr.

  When energizing the solenoid SOL and starting to retract the plunger PL from the protruding state, the suction force of the solenoid SOL is small, but the driven lever L2 is at a distance X that is relatively far from the second fulcrum L2s that is the fulcrum of the driven lever L2. Since it is started to be pushed by the drive lever L1 at the first mutual contact site P, the driven lever L2 is swung against the spring Sp force even if the suction force of the solenoid SOL is still small, and accordingly the driven roller support arm Am interlocked therewith. You can start moving. It is not necessary to increase the suction force of the soleroid SOL for starting the swing of the driven lever L2.

  When the plunger PL is further retracted and the drive lever L1 further swings the driven lever L2, the mutual contact portion of both levers gradually approaches the second fulcrum L2s, and even if the plunger PL is slightly retracted, the small reversing operation is divided. In this case, the driven lever L2 and, therefore, the driven roller support arm Am swings greatly, and the driven roller Kr is separated from the discharge roller Dr by a predetermined distance (here, a distance at which the sheet conveying force can be safely and reliably released). it can. In other words, the plunger stroke can be made smaller even when the driven lever L2 is rotated by the same angle θ than when the driven lever L2 is continuously pressed at the portion P. In this respect, the solenoid SOL need not be particularly large.

  Further, when the mutual contact portion of both levers L1 and L2 approaches the second fulcrum L2s, which is the fulcrum of the driven lever L2, a large force is required to swing the driven lever L2. Since the solenoid is retracted greatly and the solenoid attractive force with respect to the plunger PL is increased, there is no problem in the operation of each part.

When the plunger PL is completely retracted, the levers L1 and L2 come into contact with each other at the second mutual contact portion Q for placing the driven roller Kr at a predetermined distance from the discharge roller Dr.
When the solenoid SOL is switched from the energized state to the non-energized state, the driven roller Kr is pressed against the discharge roller Dr by the spring Sp force, and the plunger PL, both levers L1, L2, the driven roller support arm Am, etc. are in the state before the solenoid is energized. Return.

  Thus, according to the roller contact / separation mechanism 100, when the driven roller Kr is separated from the discharge roller Dr, it is possible to obtain a separation amount between the rollers Kr and Dr, which releases the document conveying force safely and reliably, and yet is extremely large. There is no need to

  In the automatic document feeder 901, when a large-size document that protrudes from the front edge in FIG. 6 is placed on the document placement tray 91, the front ear portion of the document hangs down on the document discharge tray 92. For this reason, there is a possibility that the document feeding into the document transport path 93 may be hindered or the document discharge onto the document discharge tray 92 may be hindered. Therefore, the remaining portion 912 of the front side edge portion of the document placing tray 91 shown in FIG. 6 may be bent so as to warp upward.

  Further, when the trailing edge of the document that has passed through the document reading unit 94 finishes passing through the flexible film valve f2 on the way to the discharge roller Dr, the film valve f2 that has been pushed up to that point is returned to the initial position by the elastic restoring force. At that time, it may collide with the conveyance path wall W as shown in FIG. Therefore, an impact relaxation film f3 may be provided in front of the film valve f2 to soften and mute the impact when the film valve f2 is elastically restored. As shown in FIG. 4, the film f3 may have a convex curve toward the valve f2 as shown in FIG. In FIG. 4, Sh is a document.

  The present invention includes a driving roller, a driven roller facing the driving roller, and a roller contact / separation mechanism that presses or separates the driven roller with respect to the driving roller, and the driven roller is pressed against the driving roller by the contact / separation mechanism. The roller contact / separation mechanism in the sheet conveying mechanism that can release the sheet conveying force by separating the driven roller from the driving roller and conveying the sheet with the sheet between the driving roller and the driven roller. A roller contact / separation mechanism that can obtain a separation amount between both rollers that can release the sheet conveying force when separating from the sheet, and does not need to be particularly large. It is possible to provide a roller contact / separation mechanism that can be used for the separation of both rollers in the original double-side reading mode of the driven roller.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus PR Printer part 9 Image reading apparatus 900 Image reading apparatus main body g1 Document platen glass 901 for document panning Automatic document conveying apparatus 91 Document placing tray 92 Document discharge tray 93 Document conveying path 94 Document reading section 95 Path Pr Pickup roller R1 Supply roller R2 Registration roller R3 Document reading roller R4 Document reading rollers r1 to r4 Driven roller Dr Discharge roller Kr Driven roller SOL Solenoid PL Plunger L1 Drive lever L1s First fulcrum Sf1 Driven end of drive lever Contact surface L2 with the free end of the lever Driven lever Sf2 Contact surface Am with the free end of the driven lever with the other end of the drive lever Am Driven roller support arm s1 Support shaft L2s Second fulcrum P, Q Sp Spring X Site P Distance from the distance Y site Q until et second supporting point to the second supporting point

Claims (5)

A driving roller, a driven roller facing the driving roller, and a roller contacting / separating mechanism that presses or separates the driven roller with respect to the driving roller, and the driven roller is pressed against the driving roller by the roller contacting / separating mechanism. A roller contacting / separating mechanism in a sheet conveying mechanism that can convey the sheet between the driving roller and the driven roller and can release the sheet conveying force by separating the driven roller from the driving roller;
A solenoid having a reciprocable plunger, a drive lever, a driven lever, a driven roller support arm that rotatably supports the driven roller, and a spring that presses the driven roller against the drive roller when the solenoid is not energized. In addition, the drive lever can swing around the first fulcrum set in the middle of the lever, and the driven lever and the roller support arm are fixedly supported on the same support shaft and swing around the second fulcrum on the same support shaft. One end of the drive lever is rotatably connected to the plunger of the solenoid and the other end abuts on the free end of the driven lever. The drive lever is placed in a protruding state and the other end of the drive lever and the free end of the driven lever are in pressure contact with the drive roller. When the solenoid is energized, the plunger moves backward to the solenoid body, the drive lever swings due to the backward movement of the plunger, and the other end of the drive lever presses the free end of the driven lever. Meanwhile, the mutual contact portion between the other end of the drive lever and the free end of the driven lever moves in a direction approaching the second fulcrum from the first mutual contact portion, and when the plunger is retracted, the driven roller is set at a predetermined distance from the drive roller. A roller contact / separation mechanism for contacting at a second mutual contact portion closer to the second fulcrum than the first mutual contact portion for placing the separated state.   The surface of the driven lever free end that is in sliding contact with the other end of the drive lever is an arc-shaped surface perpendicular to the spindle on which the driven lever is fixedly supported. The surface in sliding contact with the driven lever free end has a cross-sectional shape perpendicular to the spindle on which the driven lever is fixedly supported, and the sliding contact surface of the driven lever free end with the other end of the drive lever The roller contact / separation mechanism according to claim 1, wherein the roller contact / separation mechanism is a slidable arcuate surface.   The surface of the driven lever free end that is in sliding contact with the other end of the drive lever is a surface having a concave arc shape in cross section perpendicular to the spindle on which the driven lever is fixedly supported, and the other end of the drive roller 2. The roller contact / separation mechanism according to claim 1, wherein the surface that is in sliding contact with the free end of the driven lever is a surface having a convex arc shape in cross section perpendicular to the support shaft on which the driven lever is fixedly supported. A document tray,
The document exit tray,
A document transport path for guiding the document from the document placement tray to the document discharge tray through the document reading unit;
A roller for taking in the original on the original tray;
A registration roller for correcting the skew of the document captured by the roller;
A document reading roller and a document reading roller disposed on both sides of the document reading unit for conveying the document supplied from the registration roller through the document reading unit;
A discharge roller that can discharge a document passing through the roller after reading the document to the discharge tray, and can switch back the document discharged to the discharge tray with reverse rotation, and a driven roller that is paired with the discharge roller; ,
A circulation conveyance path that guides a document that is discharged to a discharge tray with a part of the discharge roller and switched back by reverse rotation of the discharge roller to the registration roller;
A first roller driving mechanism for driving the roller and the registration roller for taking in the document on the document placing tray to rotate forward for document feeding;
To drive the roller before document reading, the roller after document reading, and the discharge roller in conjunction with normal rotation for feeding the document, or to drive in reverse rotation to circulate and convey the document from the discharge tray to the registration roller for reading both sides of the document. A second roller drive mechanism;
An automatic document feeder provided with a roller contact / separation mechanism for separating a driven roller paired with the discharge roller from the discharge roller;
An automatic document feeder in which the roller contact / separation mechanism according to claim 1, 2 or 3 is adopted as the roller contact / separation mechanism.   The roller contact / separation mechanism includes a second roller until the leading edge of the document circulated and conveyed to the registration roller by the switchback operation by reversing the discharge roller for reading both sides of the document passes through the registration roller and reaches the roller before document reading. An automatic document conveying device for separating a driven roller paired with a discharge roller from a discharge roller when a drive mechanism switches a roller before document reading, a roller after document reading and a discharge roller from reverse rotation to normal rotation.

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