JP2000185865A - Sheet carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry a sheet stably without deteriorating a state of carrying sheets from a first guide body to a second guide body by deforming or displacing a third guide body according to a movement position obtained when the first or second guide body is moved to change a relative position of the first guide body to the second guide body. SOLUTION: A sheet carrying guide 31 comprises a separating claw 32 which separates a sheet from a copy and feed belt 216 and a movable sheet guide 33 which guides the sheet to a pre-fixing sheet guide 30. The separating claw 32 is disposed in a notch part 33a formed upstream from the movable sheet guide 33. The movable sheet guide 33 can be rotated about a rotating shaft 33a, and the tip of the movable sheet guide is brought into contact with the upstream side end part of the prefixing sheet guide 30 by its own weight. The separating claw 32 and movable sheet guide 33 are rotatably pivotally supported on a first copy frame. The sheet carrying guide 31 rises and lowers with the first copy frame, and the movable sheet guide 33 is brought into contact with the pre-fixing sheet guide 30 to rotate upward about the rotating shaft 33a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an image forming apparatus such as a copying machine or a facsimile, and conveys a sheet from an image forming section to a fixing section and a sheet from a sheet feeding section to the image forming section. The present invention relates to a sheet conveying device to be performed.

[0002]

2. Description of the Related Art Conventionally, in a digital color copying machine in which image forming units for each color are arranged side by side, a sheet is conveyed to an image forming unit for each color by a sheet conveying belt disposed opposite to the image forming unit for each color. The toner images of the respective colors are superimposed and transferred on the sheet, and the transferred toner images of the respective colors are fixed to form a full-color image.

[0003] In such an image forming apparatus, since image formation using black is performed more frequently than full-color image formation, image forming units for other colors (cyan, magenta, and yellow) are used when forming an image using only black. If the sheet is kept in contact with the sheet conveying belt, deterioration due to friction with the sheet conveying belt occurs. In order to prevent the deterioration, the photoconductors of the three-color image forming section must be driven. Since the image forming unit that is not necessary for forming an image is also driven, the durability of the image forming unit is reduced, unnecessary power is consumed, and the like. The image forming units other than black are provided so as to be able to come into contact with and separate from the sheet conveying belt, so that the image forming units other than black are separated from the sheet conveying belt when forming only the black image.

However, if the image forming section is provided so as to be capable of moving toward and away from the sheet conveying belt, that is, movable, the toner images of the respective colors (four colors) are displaced when the toner images of the respective colors (four colors) are superimposed on the sheet during full-color image formation. In order to prevent this, there is one described in JP-A-10-78708.

In the image forming apparatus described in Japanese Patent Application Laid-Open No. H10-78708, a black image forming section is disposed on the most downstream side in the sheet conveying direction, that is, on the fixing section side, and is arranged upstream of the sheet conveying belt. Side is arranged so as to be able to contact and separate from the most upstream image forming section.

[0006]

However, in the case where the black image forming section is disposed at the most downstream side and the most upstream side of the sheet conveying belt is disposed so as to be able to approach / separate (move),
Since the sheet entry side moves greatly, the relative position between the sheet feeding unit and the sheet conveyance belt changes greatly, and there has been a problem that the accuracy of position adjustment during sheet conveyance is reduced.

[0007]

According to a first aspect of the present invention, there is provided a sheet conveying apparatus for guiding a sheet conveyed by sheet conveying means, and a first guide for guiding the sheet conveyed by the sheet conveying means. A second guide disposed downstream of the sheet conveying direction, and a first guide disposed between the first guide and the second guide;
Third to guide the sheet guided by the guide to the second guide
A guide member; and a variable means for moving the position of the first guide member or the second guide member to change a relative position between the first guide member and the second guide member. The first guide body or the second guide body is deformed or displaced according to the changed position.

According to a second aspect of the present invention, the first guide is formed by sheet transport means for sucking and transporting the sheet, and the third guide is moved when the position of the first guide is moved by the variable means. An upstream sheet guide portion that moves integrally with the first guide body and an upstream end portion in contact with each other, and a downstream sheet guide that is deformed or displaced in accordance with the movement of the first guide body. .

According to a third aspect of the present invention, the downstream sheet guide of the third guide abuts on the upstream end of the second guide or the downstream end of the third guide. Is provided with a projection that forms a gap between the two so as not to contact the sheet guide surface of the second guide.

According to a fourth aspect of the present invention, there is provided a sheet conveying device, wherein the third guide is provided with sheet detecting means having a sheet detecting piece protruding from the guide surface of the third guide, and the sheet detecting means is moved by the variable means. It is provided so as to move integrally with the first guide or the second guide.

According to a fifth aspect of the present invention, in the sheet conveying apparatus, the third guide body includes an upstream sheet guide portion in which the first guide body and the upstream end portion are in contact with each other. A downstream end of the downstream sheet guide abuts on the second guide body, and the abutting portion serves as a point of action for the first guide body or the second guide body by the variable means. The downstream sheet guide is rotated according to the movement.

According to a sixth aspect of the present invention, the third guide body of the sheet conveying device is displaced or deformed so as to reduce the inclination angle of the sheet guide direction from the first guide body to the second guide body during the sheet conveyance guide. The sheet is displaced or deformed so that the inclination angle becomes large when the sheet cannot be transported.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital color copying machine which is an image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing the configuration of a digital color copying machine.

Copying machine body 1 of this digital color copying machine
The document table 111 and an operation panel (not shown)
Is provided, and an image reading unit 110 and an image forming unit 210 are provided inside the copying machine main body 1.

On the upper surface of the platen 111, the platen 111
The document is supported so that it can be opened and closed, and has a predetermined positional relationship with respect to the surface of the document table 111 (RADF: Recirculating Auto Document Document Fe).
eder) 112 is mounted.

Further, the RADF 112 first conveys the document so that one side of the document faces the image reading unit 110 at a predetermined position on the document table 111, and after reading the image on one side, the other side. The document is inverted and transported toward the document table 111 such that the surface of the document faces the image reading unit 110 at a predetermined position on the document table 111. Then, the RADF 112 discharges this document after reading the image on both sides of one document, and executes the duplex conveyance operation for the next document. The above-described document conveyance and reverse operation are controlled in relation to the operation of the entire copying machine.

The image reading section 110 is arranged below the document table 111 for reading the image of the document conveyed onto the document table 111 by the RADF 112. The image reading unit 110 includes original scanning bodies 113 and 114 that reciprocate in parallel along the lower surface of the original table 111, an optical lens 115, and a CCD line sensor 11 that is a photoelectric conversion element.
6.

The original scanning bodies 113 and 114 are composed of a first scanning unit 113 and a second scanning unit 114. The first scanning unit 113 has an exposure lamp for exposing the surface of the document image, and a first mirror for deflecting a reflected light image from the document in a predetermined direction.
1 is reciprocally moved in parallel at a predetermined scanning speed while maintaining a constant distance from the lower surface of the light-emitting device 1. The second scanning unit 114 has second and third mirrors for further deflecting the reflected light image from the document deflected by the first mirror of the first scanning unit 113 in a predetermined direction, and the first scanning unit It reciprocates in parallel with 113 while maintaining a constant speed relationship.

The optical lens 115 includes the second scanning unit 1
The reflected light image from the document deflected by the third mirror 14 is reduced, and the reduced light image is converted to a CCD line sensor 116.
An image is formed at the upper predetermined position.

The CCD line sensor 116 is for photoelectrically converting the formed light image sequentially and outputting it as an electric signal. The CCD line sensor 116 is a three-line color CCD capable of reading a black-and-white image or a color image and outputting line data separated into R (red), G (green), and B (blue) color components. . The document image information converted into an electric signal by the CCD line sensor 116 is further transferred to an image processing unit (not shown) and subjected to predetermined image data processing.

Next, the configuration of the image forming unit 210 and the configuration of each unit related to the image forming unit 210 will be described.

Below the image forming section 210, there is provided a sheet feeding mechanism 211 for separating the sheets (sheets) P stored in the sheet feeding cassette one by one and supplying the separated sheets (sheets) P to the image forming section 210. ing. Then, the sheets P separated and supplied one by one are conveyed to the image forming unit 210 at a controlled timing by a pair of registration rollers 212 disposed in front of the image forming unit 210. Further, the sheet P on which an image is formed on one side is re-supplied and conveyed to the image forming unit 210 in synchronization with the image formation of the image forming unit 210. A transfer / conveyance belt mechanism 213 is disposed below the image forming unit 210. Transfer conveyor belt mechanism 2
Reference numeral 13 denotes a transfer conveyance belt 216 stretched so as to extend substantially in parallel between the driving roller 214 and the driven roller 215.
The paper P is electrostatically attracted to the paper and transported.
In addition, a pattern image detection unit is provided near the lower side of the transfer conveyance belt 216.

Further, a fixing device 21 for fixing the toner image transferred and formed on the sheet P on the sheet P is provided downstream of the transfer and conveyance belt mechanism 213 in the sheet conveyance path.
7 are arranged. The paper P that has passed through the nip between the pair of fixing rollers of the fixing device 217 passes through a conveyance direction switching gate 218 and is discharged by discharge rollers 219 onto a paper discharge tray 220 attached to the outer wall of the copying machine main body 1. You.

The switching gate 218 switches the conveyance path of the sheet P after fixing between the path for discharging the sheet P to the copying machine main body 1 and the path for re-supplying the sheet P to the image forming section 210. It is selectively switched. The sheet P whose transport direction has been switched again toward the image forming unit 210 by the switching gate 218 is turned upside down via the switchback transport path 221, and then the image forming unit 21.
0 again.

Above the transfer belt 216 in the image forming section 210, the first image forming station Pa, the second image forming station Pb, the third image forming station Pc, and the vicinity of the transfer belt 216. The fourth image forming stations Pd are arranged in order from the upstream side of the sheet transport path.

The transfer conveying belt 216 is driven by a driving roller 214.
As a result, the sheet P is frictionally driven in the direction indicated by the arrow Z in FIG. 1 and is fed through the sheet feeding mechanism 211 as described above.
Conveyed sequentially to Pd.

Each of the image forming stations Pa to Pd has substantially the same configuration. Each of the image forming stations Pa, Pb, Pc, and Pd is a photosensitive drum 222a, 222b, or 22 that is driven to rotate in the direction of arrow F shown in FIG.
2c and 222d, respectively.

Around the photosensitive drums 222a to 222d, chargers 223a, 223b, 223c, 223d for uniformly charging the photosensitive drums 222a to 222d, respectively.
And developing devices 224a, 224b, and 2 for developing the electrostatic latent images formed on the photosensitive drums 222a to 222d, respectively.
24c, 224d and the developed photosensitive drum 222a
And discharge devices 225a, 225b, 225c, 225d for transferring the toner images on the sheets P to 222d, and cleaning devices 226a, 226b, 226c, 22 for removing the toner remaining on the photosensitive drums 222a to 222d.
6d are sequentially arranged along the rotation direction of the photosensitive drums 222a to 222d.

Each of the photosensitive drums 222a to 222d
Above the laser beam scanner unit 227
a, 227b, 227c, and 227d are provided respectively. Laser beam scanner units 227a to 227
d is a semiconductor laser device (not shown) that emits dot light modulated according to image data, a polygon mirror (deflecting device) 240 for deflecting a laser beam from the semiconductor laser device in the main scanning direction, Polygon mirror 2
The laser beam deflected by 40 is transferred to the photosensitive drum 2
Fθ lens 2 for forming an image on the surface of 22a to 222d
41, and mirrors 242, 243 and the like.

Laser beam scanner unit 227a
Is a pixel signal corresponding to a black component image of a color original image, a laser beam scanner unit 227b is a pixel signal corresponding to a cyan component image of a color original image, and a laser beam scanner unit 227c is a magenta image of a color original image. A pixel signal is input to the color component image, and a pixel signal corresponding to the yellow component image of the color original image is input to the laser beam scanner unit 227d.

As a result, the electrostatic latent images corresponding to the color-converted original image information are formed on the photosensitive drums 222a to 222d.
Formed on top. The developing device 224a includes the black toner, the developing device 224b includes the cyan toner,
The developing device 224c contains magenta toner, and the developing device 224d contains yellow toner. The electrostatic latent images on the photosensitive drums 222a to 222d are:
The image is developed with the toner of each color. As a result, the document image information color-converted by the image forming unit 210 is reproduced as a toner image of each color.

Further, between the first image forming station Pa and the paper feeding mechanism 211, a paper suction charger (brush) 2 is provided.
The paper suction charger 228 charges the surface of the transfer conveyance belt 216,
The sheet P supplied from the first image forming station Pa is securely sucked onto the transfer conveyance belt 216 in the first image forming station Pa.
To the fourth image forming station Pd without shifting.

On the other hand, a static eliminator 229 is provided almost directly above the drive roller 214 between the fourth image forming station Pd and the fixing device 217. An alternating current for separating the paper P electrostatically attracted to the transfer / transport belt 216 from the transfer / transport belt 216 is applied to the neutralizer 229.

In the digital color copying machine having the above configuration, cut sheet-shaped paper is used as the paper P. The sheet P is sent out from the sheet cassette and fed to the sheet feeding mechanism 2.
11, the leading end of the sheet P is detected by a sensor (not shown), and based on a detection signal output from the sensor, the pair of registration rollers 212 Once stopped.

Then, the paper P is sent onto the transfer / conveying belt 216 rotating in the direction of arrow Z in FIG. 1 at the timing of each of the image forming stations Pa to Pd. At this time, since the transfer conveyor belt 216 has been given a predetermined charge by the paper suction charger 228 as described above,
The sheet P is stably conveyed and supplied while passing through the image forming stations Pa to Pd.

In each of the image forming stations Pa to Pd, a toner image of each color is formed, and is superposed on the support surface of the paper P conveyed by being electrostatically attracted and conveyed by the transfer conveyance belt 216. When the transfer of the image by the fourth image forming station Pd is completed, the sheet P is sequentially peeled off the transfer / conveying belt 216 from the leading end thereof by the static eliminator 229 and guided to the fixing device 217. Finally, the sheet P on which the toner image has been fixed is discharged into a sheet discharge port (not shown).
Is discharged onto the discharge tray 220 from the paper tray.

In the above description, the laser beam scanner units 227a to 227d scan and expose a laser beam by the laser beam scanner units 227a to 227d.
Writing to 22a to 222d is performed. However, instead of the laser beam scanning unit, a writing optical system (LE) composed of a light emitting diode array and an imaging lens array is used.
D head). The LED head is smaller in size than the laser beam scanning unit, has no moving parts, and is silent. Therefore, it can be suitably used in an image forming apparatus such as a tandem type digital color copying machine which requires a plurality of optical writing units.

In the full-color mode, the transfer / conveying belt 216 comes into contact with the photosensitive drums 222a to 222d of the image forming stations Pa to Pd of each color, and the toner images developed at the image forming stations Pa to Pd are formed on paper. It is configured to transfer to a full-color image. In the monochrome mode (black mode), the transfer belt 216 contacts only the photosensitive drum 222a of the black image forming station Pa, and the photosensitive drums 222b to 222 of the other color image forming stations Pb to Pd.
It is configured such that only black images are formed without contact with 2d. Furthermore, when a jam occurs,
The transfer / conveyance belt 216 is lowered in the full-color mode and the monochrome mode to separate from the photosensitive drums 222a to 222d of the image forming stations Pa to Pd so as to form a space from which jammed paper can be removed. Is configured.

When the transfer / transport belt 216 is separated from the image forming stations Pa to Pd as described above, the transfer / transport belt 216 is disposed downstream of the transfer / transport belt 216 and upstream of the fixing device 217 in accordance with the separation. The paper transport guide 31, which is the third guide, is displaced or deformed so that the paper can be transported stably.

First, the mechanism for separating the transfer / transport belt 216 will be described, and then the sheet transport guide 31 downstream of the transfer / transport belt 216 will be described.

The separation mechanism of the transfer belt 216 will be described with reference to FIGS. FIG. 2 is a cross-sectional view showing the full color mode, FIG. 3 is a cross-sectional view showing the monochrome mode, and FIG. 4 is a cross-sectional view showing the jam processing.

As shown in FIG. 2, the transfer / transport belt 216 as the first guide includes a driving roller 214 and a driven roller 2.
15, the roller is stretched by the auxiliary roller 13 and the tension roller 14, and travels in the Z direction in the figure by rotation of these rollers.

Driving roller 214 and driven roller 215
Are driven roller shaft 214a and driven roller shaft 215, respectively.
a. The auxiliary rollers 13a and 13b and the tension roller 14 are respectively mounted by rotating shafts (not shown).

The drive roller shaft 214a, the rotation shaft of the tension roller, and the rotation shaft of the auxiliary roller 13b are rotatably supported by the first transfer frame 11. Driven roller shaft 2
15a is rotatably supported by the second transfer frame 15. The first transfer frame 11 is rotatably supported by a driven roller shaft 215a via a bearing. Further, the rotation shaft of the auxiliary roller 13 a is rotatably supported by the second transfer frame 15.

The first transfer frame 11 is connected to each of the photosensitive drums 222a to 222d via a transfer / transport belt 216.
The transfer discharge devices 225a to 225d elastically biased by springs 12a to 12d toward the side are held. In this case, the transfer dischargers 225a to 225d are regulated so that the movement stroke with respect to the first transfer frame 11 is constant.

Below the first transfer frame 11, a drive mechanism 16 for separating the transfer / transport belt 216 is provided on the second transfer frame 15. The drive mechanism 16 includes a drive motor 17, transmission gears 18 and 19, a conveyor belt positioning shaft 20, and a female thread 21.
Gear teeth are formed on the output shaft 17 a of the drive motor 17 and mesh with the transmission gear 18. The conveyor belt positioning shaft 20 includes a gear portion 20a and a male screw portion 20b.
The gear portion 20a meshes with the transmission gear 19, and the male screw portion 20b meshes with the female screw portion 21.

With this configuration, when the drive motor 17 rotates forward, the conveyor belt positioning shaft 20 moves up, and when the drive motor 17 rotates in the reverse direction, the conveyor belt positioning shaft 20 moves down. The contact portion 20c of the transfer belt positioning shaft 20 contacts the lower surface of the first transfer frame 11, and the transfer transfer belt 216 and the drive roller 21
4. supporting the first transfer frame 11 provided with the transfer dischargers 225a to 225d and the like,
Of the photosensitive drums 222a to 222d.

In the full-color mode, the driving mechanism 16 having the above-described structure positions the conveyor belt positioning shaft 20c at the uppermost position and positions the first transfer frame 11 at the uppermost position. As shown in FIG. The photoconductor drums 222 a of the image forming stations Pa to Pd are placed on the paper P conveyed by the transfer conveyance belt 216 by positioning the transfer conveyance belt 216 in contact with the transfer conveyance belt 216.
The toner images of the respective colors formed on 〜 to 222 d are sequentially superimposed and transferred.

In the monochrome mode, the transfer / transport belt 216 that has been in contact with the photosensitive drums 222a to 222d of all the image forming stations Pa to Pd in the full color mode is driven to move below the first transfer frame 11. When the motor 17 rotates, the first transfer frame 11 moves downward, and the drive roller 214 side of the transfer conveyance belt 216 moves in a direction away from the image forming station Pd, and as shown in FIG. It comes into contact only with the photoconductor drum 222a of Pa and separates from the image forming stations Pb to Pd of other colors.

At this time, since the auxiliary roller 13a is supported by the second transfer frame 15, the first transfer frame 1
1 does not move with the rotation (separation movement) of the photosensitive drum 222 a of the transfer conveyance belt 216 in the transfer area between the photosensitive drum 222 a and the transfer discharger 2225 a.
The contact state with “a” is in a stable state.

Accordingly, it is not necessary to drive the image forming stations Pb to Pd just to convey the sheet P on which the black toner image has been transferred to the fixing device 217 in the monochrome mode. It is possible to improve the durability, and furthermore, the paper feeding side of the transfer conveyance belt 216 does not move, and the relative position between the registration roller 212 and the paper conveyance side of the transfer conveyance belt 216 does not change. The paper P can be transported in a stable state without deteriorating the positional consistency at the time of transport.

Next, the transfer / conveying belt 21 during the jam processing
The separation mechanism 6 will be described.

On the lower surface of the second transfer frame 15 in FIG. 2, an elevating mechanism 24 is provided. This lifting mechanism 24
Is the upstream side of the transfer conveyance belt 217 (the driven roller 215
Side) and the downstream side (drive roller 214 side).
A rotation plate 25 rotatably provided about the axis 5a, a link plate 27 connecting the rotation plates 25, and an upstream support shaft 25;
a and an operating handle (not shown) provided integrally with the a.

The rotation plate 25 and the link plate 27 are connected to the link fulcrum 2
5b. The rotating plate 25 is provided with a lifting roller 26. This lifting roller 26
Abuts on the notch 15 a of the second transfer frame 15 to support the second transfer frame 15.

When the user operates the operation handle when a jam occurs, the upstream support shaft 25a integrally rotates together with the upstream rotation plate 25. When the rotation plate 25 on the upstream side rotates, the rotation plate 25 on the downstream side also rotates in the same direction as the rotation plate 25 on the upstream side by the link plate 27. As a result, the second transfer frame 15 moves up and down, and the transfer conveyance belt 216 can move up and down.

The guide roller 23 restricts the second transfer frame 15 from moving in the horizontal direction when the second transfer frame 15 moves up and down. In this state, since all the image forming stations Pa to Pd are not close to the transfer / conveyance belt 216, the user can perform appropriate processing for paper jams on the transfer / conveyance belt 216. By these mechanisms, the transfer conveyance belt 216 causes the photosensitive drums 222a to 222
and a gap can be formed between them.

Next, the paper transport guide 31 which is displaced in conjunction with the movement of the transfer transport belt 216 toward and away from the image forming stations Pa to Pd will be described.

As described above, the transfer conveyance belt 216 is configured to move up and down according to each mode, but the fixing device 217 is configured not to move. For this reason, even if the sheet conveyed toward the fixing device 217 by the transfer conveyance belt 216 is in the monochrome mode in which the transfer conveyance belt 216 is lowered, the sheet is appropriately directed toward the fixing device 217 as in the full color mode. Must be transported to Immediately before the fixing device 217, a pre-fixing paper guide 30, which is a second guide, is provided, and a pair of fixing rollers 217a and 217b of the fixing device 217 are provided.
In order to prevent wrinkles from occurring when the sheet P is nipped and conveyed to and fixed in the fixing nip portion of the paper guide 30,
And the fixing roller pair 217a, 21
7b.

This is because the fixing roller pair 217a, 217b
When the leading edge of the paper P enters the paper P, the paper P is curved so that one shallow peak or valley is formed at the center of the paper P with respect to the direction orthogonal to the transport direction of the paper P. ,
The occurrence of wrinkles on the paper P is greatly reduced. However, for example, when there is a peak or a valley in a place other than the center of the paper P,
In the case where the degree of curvature of the sheet P is large, and in the case where there is a plurality of peaks or valleys even if the curvature is small, the occurrence rate of wrinkles is extremely high.

When the position of the transfer / transport belt 216 changes (moves) from the full-color mode to the monochrome mode, the pre-fixing paper guide 30 and the transfer / transport belt 216 are changed.
If the center of the sheet P remains high, the leading edge of the sheet P once moves upward and then drops, so that the fixing roller pair 217a, 217b is moved in a state where the leading edge of the sheet P is greatly swung.
Infiltration in between, and the occurrence rate of wrinkles becomes very high.

The leading edge of the sheet P does not swing greatly, and the leading edge of the sheet P is prevented from being curved so as to cause wrinkles.
The first embodiment of the paper transport guide 31 for transporting the paper P between the pair of fixing rollers 217a and 217b is configured as follows. FIG. 5A is a cross-sectional view showing the state of the paper transport guide 31 in the full color mode, and FIG.
FIG. 5C is a cross-sectional view illustrating the state of the paper transport guide 31 in the monochrome mode, FIG. 5C is a cross-sectional view illustrating the state of the paper transport guide 31 during jam clearance, and FIG.
1 is a perspective view of FIG.

As shown in FIGS. 5A and 6, the paper transport guide 31 includes a release claw 32 serving as an upstream paper guide for releasing the paper P from the transfer transport belt 216, and a paper P.
And a movable paper guide 33 which is a downstream paper guide for guiding the paper P to the pre-fixing paper guide 30, and a peeling claw 32 is provided in a notch 33 b formed on the upstream side of the movable paper guide 33. .

The peeling claw 32 is formed by a spring having a weak urging force that does not damage the transfer / conveying belt 216.
, The leading end of which is a transfer conveyance belt 21.
6 is urged to be pressed. The movable paper guide 33 is rotatable about a rotation shaft 33a, and the leading end of the movable paper guide 33 is in contact with the upstream end of the pre-fixing paper guide 30 by its own weight. Peeling claw shaft 3
2a and the rotating shaft 33a of the movable paper guide 33 are rotatably supported by the first transfer frame 11, and the driving mechanism 1
6 and the operation of the elevating mechanism 24 move up and down together with the first transfer frame 11.

With this configuration, the mode is shifted from the full color mode to the monochrome mode, and the posture of the movable paper guide 33 changes as shown in FIG. 5B. That is,
When switching from full color mode to monochrome mode,
The transfer frame 11 is changed from the state shown in FIG. 2 to the state shown in FIG. 3 by the operation of the drive mechanism 16 (the drive roller 214 side is lowered). Then, the peeling claw 32 and the movable paper guide 33 that are pivotally supported by the first transfer frame 11 also move (fall).

At this time, since the fixing device 217 is fixedly provided, the pre-fixing paper guide 30 does not move, and the downstream end of the movable paper guide 33 is connected to the pre-fixing paper guide 30.
The movable paper guide 33 pivots upward about the pivot shaft 33a, and the movable paper guide 33 pivots upward about the pivot shaft 33a. The sheet P thus guided is guided by the movable sheet guide 33 and reaches the pre-fixing sheet guide 30.

At this time, the downstream side of the paper guide surface, which is the upper surface of the peeling claw 32, is located above the paper guide surface, which is the upper surface of the movable paper guide 33. The leading end does not catch on the movable paper guide 33.

The inclination angle of the paper guide surface of the peeling claw 32 with respect to the horizontal, the inclination angle of the paper guide surface of the movable paper guide 33, and the inclination angle of the paper guide surface which is the upper surface of the pre-transfer paper guide 30 are sequentially increased. Has become.

As described above, in the monochrome mode, the inclination angle of the paper guide surface of the movable paper guide 33 is
The movable paper guide 33 changes its posture so as to be at an intermediate angle between the inclination angle of the paper guide surface of the paper guide surface and the inclination angle of the paper guide surface of the paper guide 30 before transfer.
The leading end of the sheet P separated from the sheet P is always guided on the upwardly inclined guide surface, the swinging of the leading end of the sheet P does not increase, and the pair of fixing rollers 217a and 217b of the fixing device 217 are provided.
And the paper P is less likely to be wrinkled.

When the elevating mechanism 24 is operated during the jam clearance, the paper transport guide 31 is further lowered from the position in the monochrome mode of FIG. 5B, as shown in FIG. 5C. . At this time, the movable paper guide 33 of the paper transport guide 31 is greatly inclined as compared with the state shown in FIG. 5B, but the paper P is not transported during the jam clearance, so that the inclination of the movable paper guide 33 becomes large. However, there is no particular problem.

As described above, the movable paper guide 33 rotates about the rotation shaft 33 a in accordance with the elevation of the transfer / conveyance belt 216, and the downstream end of the movable paper guide 33 is always the same as the unfixed paper guide 30. Since it is located above the upstream end and covers the upstream end of the pre-fixing paper guide 30, the transfer / transport belt 216 moves up and down to move the transfer / transport belt 216 and the pre-fixing paper guide 30 together. Is not changed, there is no level difference between the sheet guide surfaces of the separation claw 32, the movable sheet guide 33, and the pre-fixing sheet guide 30, which hinders the sheet conveyance. No jams or breaks occur.

The contact point of the movable sheet guide 33 that contacts the pre-fixing sheet guide 30 is X ₁ in the full color mode (FIG. 5A) and in the monochrome mode (FIG. 5B). Assuming that the contact point is X ₂ and the contact point during jam processing (FIG. 5C) is X ₃ , the contact points X ₁ , X ₂ , and X ₃ are located downstream of the paper guide surface of the paper guide 30 before fixing. It will be located in order from the side.

In other words, at the time of jam clearance or switching of the mode from the full-color mode to the monochrome mode, the movable paper guide 33 rotates about the rotation shaft 33a as the transfer / transport belt mechanism 213 of the transfer / transport belt 216 moves down. The movable paper guide 33 rotates, and the force for rotating the movable paper guide 33 acts on the movable paper guide 33 from the contact point of the movable paper guide 33 with the pre-fixing paper guide 30.

This contact point is connected to the transfer and transport belt mechanism 21.
When the movable paper guide 33 is rotated upward by the lowering of the transfer belt 3, the transfer conveyance belt is located near the downstream end (tip) of the movable paper guide 33 away from the rotation shaft 33a (contact point X ₁ ). Even when the mechanism section 213 descends at a high speed, the movable paper guide 33 does not jump up.

Next, a second embodiment of the paper transport apparatus of the present invention
Is configured as shown in FIG. 7A is a cross-sectional view showing the state of the paper transport guide 31 in the full color mode, FIG. 7B is a cross-sectional view showing the state of the paper transport guide 31 in the monochrome mode, and FIG.
FIG. 3C is a cross-sectional view illustrating a state of the paper transport guide 31 during a jam clearance.

As shown in FIG. 7, the pre-fixing paper guide 30
A projection 30a is formed on the upstream side of the paper guide surface of the movable paper guide 33, and the projection 30a contacts the movable paper guide 33 to support the downstream end of the movable paper guide 33.

The position at which the projection 30a comes into contact with the back surface of the movable paper guide 33 moves toward the distal end of the downstream end of the movable paper guide 33 as the movable paper guide 33 moves down together with the transfer / transport belt mechanism 213. ing.

That is, the rotating shaft 33 of the movable paper guide 33
The distance from a to the contact point is determined by the transfer / conveyance belt mechanism 213.
Of the movable paper guide 33 to prevent the movable paper guide 33 from jumping upward.

The posture of the movable paper guide 33 in the full color mode shown in FIG. 7A is such that the paper P peeled by the peeling claw 32 is guided slightly below the horizontal direction.
The sheet P is guided to the sheet guide surface of the pre-fixing sheet guide 30 so that the leading end of the sheet P swings little.

The posture of the movable paper guide 33 in the monochrome mode shown in FIG. 7B is such that the movable paper guide 33 has an inclination angle with respect to the horizontal direction so that the leading end of the peeled paper P does not swing. The inclination angle of the peeling claw 32 with respect to the horizontal direction of the paper guide surface, and the paper guide 30 before fixing.
The movable paper guide 33 moves so as to be at an intermediate angle with the inclination angle of the paper guide surface with respect to the horizontal direction of the paper guide surface. When the contact between the movable paper guide 33 and the movable paper guide 33 is displaced, the movable paper guide 33 is smoothly rotated (changed in state), no impact is exerted on other members, and the transportability of the paper P may be deteriorated. Absent.

The attitude of the movable paper guide 33 during the jam processing shown in FIG. 7C is determined by the inclination angle of the movable paper guide 33 with respect to the horizontal direction of the paper guide surface and the inclination of the peeling claw 32 with respect to the horizontal direction of the paper guide surface. The angle is larger than the inclination angle of the pre-fixing paper guide 30 with respect to the horizontal direction of the paper guide surface.

However, when the jam is cleared, the first embodiment is used.
Similarly to the above, since the paper P is not conveyed, the conveyance of the paper P is not impaired, no jam occurs, and no inconvenience occurs.

The protrusion 30a of the paper guide 30 before fixing is provided.
As a result, a gap is formed between the paper guide surface of the pre-fixing paper guide 30 and the movable paper guide 33, so that the paper guide surface of the pre-fixing paper guide 30 should be Even when coated with a fluororesin such as Teflon, the movable paper guide 33 does not directly contact the paper guide surface of the pre-fixing paper guide 30 due to the protrusion 30a, and the film of the paper guide surface made of the fluororesin is damaged. Can be prevented.

The projections 30a are formed on the paper guide surface of the paper guide 30 before fixing. As shown in FIG. 8, the projections 30a are formed on the back surface (lower surface) of the downstream end of the movable paper guide 33. 34 may be formed.

Next, a fourth embodiment of the paper conveying apparatus of the present invention will be described.
Is configured as shown in FIG. FIG. 9A is a cross-sectional view illustrating the state of the paper transport guide 31 in the full color mode, and FIG. 9B is a cross-sectional view illustrating the state of the paper transport guide 31 in the monochrome mode.

As shown in FIG. 9, in the fourth embodiment, a paper detector 35 is disposed on the paper transport guide 31. The paper detector 35 includes a detecting unit 35a for detecting the transport of the paper P. The detection lever 3 is a sheet detection piece that is configured so as to be rotatable integrally with the detection unit 35 by the shaft 35 b and protrudes upward from the sheet guide surface of the movable sheet guide 33.
5c, and the paper detector 35 is moved up and down integrally with the transfer / conveyance belt mechanism 213 so as to move up and down.
It is fixed to the transfer frame 11. Then, the detection unit 35
a has an optical path 35d from the light emitting element to the light receiving element,
The sheet P is detected based on whether or not the detection lever 35c blocks the optical path 35d.

When the transfer / transport belt mechanism 213 descends from the full-color mode shown in FIG. 9A to the monochrome mode shown in FIG. 9B, the sheet detector 35 descends together with the first transfer frame 11. Although the amount of protrusion of the detection lever 35c of the paper detector 35 from the movable paper guide 33 rotated by this lowering is smaller than that in FIG. 9A, the inclination of the paper detector 35 itself is smaller, so that the detection lever The state where 35c blocks the optical path 35d is a stable state.

That is, when the paper detector 35 is fixed to the movable paper guide 33 so as to rotate integrally with the movable paper guide 33 as shown in FIG.
When the movable paper guide 33 rotates in the monochrome mode as described above, the inclination angle of the paper detector 35 increases, and the portion of the detection lever 35c that blocks the optical path 35d is closer to the end of the detection lever 35c. When the detection lever 35c returns after the conveyance of the P, that is, after the passage, the state of the optical path 35d is blocked and unblocked by the swing of the detection lever 35c. There was a case where a chattering phenomenon occurred and a jam was erroneously detected.

When the detection lever 35c is elastically urged clockwise in the figure by a coil spring or the like to prevent this erroneous detection, the chattering phenomenon due to the swing of the detection lever 35c can be prevented. When P is conveyed and collides with the detection lever 35c,
The impact due to the collision increases, which causes a shift of the toner image transferred onto the sheet P.

Therefore, as shown in FIG. 9, by fixing the paper detector 35 to the first transfer frame 11 so as to descend integrally with the first transfer frame 11,
Since the conveyance of the sheet P can be reliably detected and the sheet detector 35 can surely detect the sheet, the movable sheet guide 33 is notched to dispose the detection lever 35c of the sheet detector 35. Even if the portion is formed, it is possible to prevent the strength of the movable paper guide 33 from decreasing.

In the above-described embodiment, the first guide is the transfer / transport belt 216, and the transfer / transport belt 21
6 and a paper guide 30 before fixing of a fixing device serving as a second guide body
The transfer conveyance belt 216 is formed so as to be movable downstream so as to change the relative position with respect to the transfer conveyance belt 216.
6 is a second guide, and a paper guide provided on the upstream side of the transfer conveyance belt 216 for conveying the sheet P to the transfer conveyance belt 216 is a first guide, and the upstream side of the transfer conveyance belt 216 is formed to be movable. Then, the transfer / conveying belt 216
The paper transport guide 31 is provided between the paper transport guide 216 and the paper guide, so that even if the relative positional relationship between the transfer transport belt 216 and the paper guide changes, the paper P
Is transported in a stable state, and a decrease in the alignment accuracy of the paper position is prevented so that the paper is not transported obliquely. Further, the present invention can be applied not only to the transfer conveyance belt but also to other paper conveyance means.

In this embodiment, the present invention is applied to a structure in which only one of the first guide member and the second guide member is movably provided. However, both the first guide member and the second guide member are used. The present invention may also be applied to a device which is provided so as to be movable together. In a device in which the relative positional relationship between the first guide member and the second guide member changes, a sheet transport guide is provided between the first and second guide members. By carrying the paper from the first guide to the second guide in a stable state, deterioration of the paper transport state caused by a change in the relative positional relationship between the two is brought into an appropriate transport state.

[0092]

According to the first aspect of the present invention, there is provided a sheet conveying apparatus comprising:
First to change the relative position between the guide and the second guide
When the guide member or the second guide member moves, the third guide member is deformed or displaced in accordance with the moved position, so that the state of transporting the sheet from the first guide member to the second guide member is not reduced. The sheet can be conveyed in a stable state.

In the sheet conveying apparatus according to the second aspect, even when the first guide, which is the sheet conveying means for sucking and conveying the sheet, is moved, the upstream sheet guide portion of the third guide is moved by the first sheet. Because it moves integrally with the guide,
The sheet can be reliably received from the guide, and can be conveyed to the second guide in a stable state. Further, for example, when a sheet conveying unit serving as a first guide is used for conveying a sheet to an image forming unit of an image forming apparatus and conveying a sheet on which a toner image is formed by the image forming unit,
Since the third guide body moves integrally with the first guide body,
Without damaging the surface of the first guide body by the guide body, it is possible to prevent the image quality from deteriorating due to the influence of the scratch when forming a halftone image in the image forming unit.

According to the third aspect of the present invention, since the gap is formed between the sheet guide surface of the second guide and the sheet guide surface of the second guide, a gap is formed between the two by the projection. The guide surface of the sheet of the second guide body can be prevented from being damaged by the contact of the parts. Further, in the case where the guide surface of the sheet of the second guide body is coated with a fluororesin such as Teflon in order to improve sheet transportability, peeling of the fluororesin film can be reliably prevented. .

In the sheet conveying apparatus according to the fourth aspect, since the sheet detecting means is provided so as to move integrally with the first guide or the second guide moved by the variable means, the third guide is provided. Even if it moves, the amount of protrusion of the sheet detection piece of the sheet detection means does not change so much, and the conveyance of the sheet can be accurately detected. Further, since the sheet detecting means moves with the first guide body or the second guide body, the inclination of the sheet detecting means can be small. For example, the sheet detecting piece can be moved vertically by its own weight and horizontally by the contact at the time of sheet conveyance. When the sheet is conveyed by switching the position, the change in the vertical position of the sheet detection piece due to its own weight can be suppressed, and erroneous detection due to the movement of the sheet detection means can be prevented.

According to a fifth aspect of the present invention, in the sheet conveying apparatus, the third guide body is provided with an upstream sheet guide portion in which the first guide body and the upstream end portion are in contact with each other. A downstream end of the downstream sheet guide abuts on the second guide body, and the abutting portion serves as a point of action, the first guide body or the second guide body by the variable means. Since the downstream sheet guide is rotated in accordance with the movement of the third guide, the contact position between the downstream sheet guide and the second guide moves sequentially in accordance with the movement of the third guide. The downstream sheet guide does not move suddenly during the movement, and damage due to collision with other members of the downstream sheet guide can be prevented.

In the sheet conveying apparatus according to the sixth aspect, when the conveyance of the sheet is impossible, for example, the third guide body is displaced or deformed so that the inclination angle of the third guide body becomes large at the time of jam processing. The amount of movement of the guide body can be increased, and the jam clearing operation can be easily performed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a digital color copying machine according to the present invention.

FIG. 2 is a cross-sectional view illustrating a sheet conveying device in a full-color mode in a full-color copying machine according to a first exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view of the full-color copying machine according to the first embodiment of the present invention in a monochrome mode of the sheet conveying apparatus.

FIG. 4 is a cross-sectional view showing the sheet conveying device in the full-color copying machine according to the first embodiment of the present invention during a jam processing.

FIGS. 5A and 5B are enlarged cross-sectional views of a main part of the sheet conveying apparatus according to the first embodiment of the digital color copying machine of the present invention, in which FIG. 5A shows a full color mode, FIG. ) Indicates the time of jam clearance.

FIG. 6 is a perspective view of a main part of the sheet conveying device of the digital color copying machine according to the first exemplary embodiment of the present invention.

FIGS. 7A and 7B are enlarged cross-sectional views of a main part of a sheet conveying apparatus according to a second embodiment of the digital color copying machine of the present invention, wherein FIG. 7A shows a full color mode, FIG. ) Indicates the time of jam clearance.

FIG. 8 is an enlarged sectional view of a main part of a sheet conveying apparatus according to a third embodiment of the digital color copying machine of the present invention.

FIGS. 9A and 9B are enlarged cross-sectional views of a main part of a sheet conveying apparatus according to a fourth embodiment of the digital color copying machine of the present invention, wherein FIG. 9A shows a full color mode and FIG. 9B shows a monochrome mode.

FIG. 10 is a digital color copier according to a fourth embodiment of the present invention.
FIG. 9 is a cross-sectional view of a comparative example for comparing with a sheet conveying device of FIG.

[Explanation of symbols]

 Reference Signs List 11 first transfer frame 15 second transfer frame 16 drive mechanism 24 elevating mechanism 30 paper guide before transfer 31 paper transport guide 32 peeling claw 33 movable paper guide 216 transfer transport belt 217 fixing device

Continued on the front page (72) Inventor Tetsutaka Okazaki 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Masashi Hirai 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Sharp (72) Inventor Fumio Shimazu 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Co., Ltd. (72) Inventor Kiyoshi Tomi 22-22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F-term ( Reference) 3F053 AA19 EA02 EC02 LA02 LB01

Claims (6)

[Claims] A first guide for guiding a sheet conveyed by a sheet conveying means; and a second guide disposed downstream of the first guide in a sheet conveying direction.
A guide member, a third guide member disposed between the first guide member and the second guide member, and guiding a sheet guided by the first guide member to the second guide member; Variable means for moving the position of the first guide body or the second guide body in order to change the relative position with respect to the second guide body; (2) A sheet conveying device, which deforms or displaces according to the position of a guide. 2. The method according to claim 1, wherein the first guide is formed by sheet conveying means for sucking and conveying a sheet, and the third guide is formed by moving the first guide by a variable means. An upstream sheet guide portion that moves integrally with the upstream end portion in contact therewith;
The sheet conveying device according to claim 1, wherein the sheet conveying device is formed by a downstream sheet guide that is deformed or displaced in accordance with the movement of the guide. 3. The downstream end of the second guide body or the downstream end of the third guide body is in contact with the downstream sheet guide of the third guide body, and the downstream sheet guide is a sheet of the second guide body. 3. The sheet conveying apparatus according to claim 2, further comprising a projection that forms a gap between the two so as not to contact the guide surface. 4. The third guide body is provided with sheet detection means having a sheet detection piece protruding from a guide surface of the third guide body, wherein the sheet detection means is moved by a variable means. The sheet conveying device according to claim 1, wherein the sheet conveying device is provided so as to move integrally with the two guides. 5. An upstream sheet guide section in which the third guide body is in contact with the first guide body at an upstream end, and a downstream sheet guide rotatably supporting the upstream end. The downstream end of the downstream sheet guide abuts on the second guide body, and the abutting portion serves as a point of action, and the downstream end is moved in accordance with the movement of the first guide body or the second guide body by the variable means. The sheet conveying device according to claim 1, wherein the side sheet guide is rotated. 6. The third guide body is displaced or deformed so as to reduce the inclination angle of the sheet guide direction from the first guide body to the second guide body at the time of sheet conveyance guide. 2. The sheet conveying apparatus according to claim 1, wherein the sheet is displaced or deformed so as to increase the inclination angle.