JP2020083553A - Medium transport guide and image forming apparatus - Google Patents

Abstract

To provide a medium transport guide capable of stably transporting a medium regardless of the width of the medium.SOLUTION: A medium transport guide has a plate part 61 formed extending widthwise of a medium and guide ribs 62, 62-1 to 62-4 formed at a plurality of points in a widthwise direction of the plate part 61. In a central portion in a widthwise direction of the plate part 61, a central guide part Ar1 is formed by the guide ribs 62-1 to 62-4 in the number corresponding to a medium width of a medium having a minimum width. On both sides of the central guide part Ar1, medium induction parts are formed to induce both side edges of the medium and flatten the medium. Even if both side edges of the medium are curled, both side edges of the medium are made flat by the medium induction parts and hence no interference occurs between both side edges of the medium and the guide rib 62.SELECTED DRAWING: Figure 1

Description

The present invention relates to a medium transport guide and an image forming apparatus.

2. Description of the Related Art Conventionally, an image forming apparatus such as a printer, a copying machine, a facsimile, and a multifunction peripheral, for example, an electrophotographic printer includes an image forming unit, and in the image forming unit, a toner image is formed on the surface of a photosensitive drum, The toner image is transferred onto a sheet as a medium by a transfer roller and fixed on the sheet by a fixing device to form an image on the sheet.

By the way, the paper fed from the paper cassette is conveyed in the paper conveyance path provided in the main body of the printer, that is, in the main body of the apparatus, and after the image is formed, is ejected to the outside of the main body of the apparatus. Then, a separator serving as a medium transport guide is arranged in the sheet transport path to guide the sheet in a predetermined transport direction (see, for example, Patent Document 1).

JP, 2005-160706, A

However, the conventional separator cannot stably guide the paper depending on the width of the paper.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the conventional separators described above and to provide a medium conveyance guide and an image forming apparatus capable of stably conveying the medium regardless of the width of the medium.

Therefore, the medium transport guide of the present invention has a plate portion formed to extend in the width direction of the medium and guide ribs formed at a plurality of positions in the width direction of the plate portion.

Then, a central guide portion is formed at the central portion in the width direction of the plate portion by a number of guide ribs corresponding to the medium width of the medium having the minimum width.

Further, medium guiding portions for guiding both side edges of the medium to flatten the medium are formed on both sides of the central guiding portion.

According to the present invention, the medium transport guide has the plate portion formed to extend in the width direction of the medium and the guide ribs formed at a plurality of positions in the width direction of the plate portion.

Then, a central guide portion is formed at the central portion in the width direction of the plate portion by a number of guide ribs corresponding to the medium width of the medium having the minimum width.

Further, medium guiding portions for guiding both side edges of the medium to flatten the medium are formed on both sides of the central guiding portion.

In this case, even if both side edges of the medium are curled, both side edges of the medium are flattened by the medium guiding portion, so that the both side edges of the medium and the guide ribs do not interfere with each other.

Therefore, the medium can be stably transported regardless of the width of the medium.

It is a principal part perspective view of the conveyance path switching mechanism in embodiment of this invention. 1 is a schematic diagram of a printer according to an embodiment of the present invention. It is a reference diagram showing a state of a sheet guided by the separator. It is sectional drawing which shows the periphery of the conveyance path switching mechanism in embodiment of this invention. FIG. 3 is a plan view of the transport path switching mechanism according to the embodiment of the present invention. It is a principal part top view of the conveyance path switching mechanism in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a color printer as an image forming apparatus will be described.

FIG. 2 is a schematic diagram of the printer according to the embodiment of the present invention.

In the figure, 10 is a printer, and Cs is a housing of the printer 10. The casing Cs is provided so as to be openable and closable with respect to the main body of the printer 10, that is, the apparatus main body Bd, and includes a top wall Wt that constitutes a cover, and first and second side walls. A stacker Sk for stacking sheets (not shown) as a medium is formed with the surface on which the color image is formed facing down. An auxiliary stacker (not shown) for stacking sheets of paper is formed on one of the first and second side walls with the surface on which the color image is formed facing up.

Further, 11Bk, 11C, 11M and 11Y are image forming units (ID units) of respective colors of black, cyan, magenta and yellow which are detachably attached to the apparatus body Bd. Each of the image forming units 11Bk, 11C, 11M, and 11Y is arranged on the photosensitive drum 13 as an image carrier, the photosensitive drum 13, and a charging roller as a charging device and a developer carrying member, which are not shown. A developing roller as a body, a cleaning device, etc. are provided.

An arm am is disposed adjacent to each of the image forming units 11Bk, 11C, 11M, and 11Y and hung from the top wall Wt, and the end of each arm am faces the photoconductor drum 13. Then, the LED head 12 as an exposure device is arranged.

Reference numeral 14 denotes a paper cassette serving as a medium storage unit for storing the paper. A hopping roller 101 for feeding the paper in the paper cassette 14 is provided at the front end of the paper cassette 14, and the fed paper is the first medium transport path. The sheet feeding roller 102 that feeds the sheet to the sheet feeding path Rt1 and the separating roller 103 that is brought into contact with the sheet feeding roller 102 and separates the sheets one by one are rotatably arranged.

Further, m1 and m2 are a pair of conveying rollers which are arranged in the sheet conveying path Rt1 and convey the sheet supplied from the sheet cassette 14.

Further, u1 is a transfer unit which is arranged on the downstream side of the transport roller pair m2 in the paper transport path Rt1 so as to face the image forming units 11Bk, 11C, 11M and 11Y.

The transfer unit u1 includes a driving roller R1 rotatably arranged below the image forming unit 11Bk, a driven roller R2 rotatably arranged below the image forming unit 11Y, the driving roller R1 and a driven roller R2. And a transfer roller 16 as a transfer member that is rotatably disposed so as to face the photosensitive drum 13 with the transfer belt 15 interposed therebetween.

Further, 31 is a fixing device as a fixing device disposed on the downstream side of the image forming units 11Bk, 11C, 11M and 11Y and the transfer unit u1 in the paper transport path Rt1, and the fixing device 31 is the first fixing device. A heating roller 32 as a fixing member and a pressure roller 33 as a second fixing member are provided.

Reference numeral 35 denotes a separator as a medium conveyance guide, which is swingably disposed on the downstream side of the fixing device 31 in the sheet conveyance path Rt1, and the separator 35 causes the sheet to be conveyed along the sheet conveyance path Rt1. Are discharged to the outside of the apparatus main body Bd, or are sent to a paper transport path Rt2 as a second medium transport path formed by branching from the paper transport path Rt1.

A transport roller pair m3 is disposed downstream of the separator 35 in the paper transport path Rt1 so as to be adjacent to the separator 35, and a discharge roller pair m4 is disposed downstream of the transport roller pair m3. Further, a conveyance roller pair m5 is arranged on the downstream side of the separator 35 in the paper conveyance path Rt2. The pair of conveying rollers m3 is composed of a conveying roller 43 as a first roller and a pinch roller 44 as a second roller arranged in contact with the conveying roller 43. A transport path switching mechanism M1 is formed by the separator 35 and the transport roller pair m3.

On the downstream side of the transport roller pair m5 in the paper transport path Rt2, a paper retracting unit Rp for temporarily retracting the paper when performing double-sided printing on the paper is formed. A pair m6 is provided.

Further, in order to reverse the sheet retracted to the sheet retracting section Rp, a sheet conveying path Rt3 is formed as a third medium conveying path by branching from the sheet conveying path Rt2, and the sheet conveying path Rt3 is configured to convey rollers. Pairs m7 to m9 are provided.

Next, the operation of the printer 10 will be described.

In each of the image forming units 11Bk, 11C, 11M, and 11Y, the photosensitive drum 13 is rotated by a driving unit (not shown), and the charging roller uniformly charges the surface of the photosensitive drum 13. Next, the LED head 12 irradiates the photoconductor drum 13 with light corresponding to the image signal to form an electrostatic latent image as a latent image on the photoconductor drum 13.

Then, the developing roller develops the electrostatic latent image and attaches a toner (not shown) as a developer onto the photoconductor drum 13 to form a toner image as a developer image.

The sheets accommodated in the sheet cassette 14 are fed from the sheet cassette 14 by the hopping roller 101, separated one by one by the sheet feeding roller 102 and the separation roller 103, and fed to the sheet conveying path Rt1, and the conveying roller pair m1. , M2, and are sent between the image forming units 11Bk, 11C, 11M and 11Y and the transfer unit u1. Then, the toner images on the respective photoconductor drums 13 are sequentially transferred onto the paper in a superimposed manner, and a color toner image is formed on the paper.

The sheet on which the toner image is formed is sent to a fixing device 31, and in the fixing device 31, it is heated and pressed by a heating roller 32 and a pressure roller 33, whereby a color toner image is fixed on the sheet. And a color image is formed.

Then, in the case of single-sided printing, the sheet on which the color image is formed is guided to the sheet transport path Rt1 by the separator 35, transported by the transport roller pair m3, and then discharged to the outside of the apparatus main body Bd by the discharge roller pair m4. It is loaded on the stacker Sk.

Further, in the case of double-sided printing, the sheet on which the color image is formed is guided to the sheet conveyance path Rt2 by the separator 35, is retracted to the sheet retraction section Rp, is then inverted, and is sent to the sheet conveyance path Rt3. In the sheet transport path Rt3, the sheet is transported by the transport roller pairs m7 to m9 and sent to the sheet transport path Rt1.

By the way, the paper is guided to the paper transport path Rt1 or the paper transport path Rt2 by the separator 35. However, when a narrow paper is used, if the medium angle of the paper is curled, the paper is stabilized. Cannot be transported.

FIG. 3 is a reference diagram showing the state of the sheet guided by the separator.

In the figure, Rt1 and Rt2 are paper transport paths, 35 is a separator, and 51 is a guide that is arranged so as to face the separator 35 in the paper transport path Rt1. A guide 52 (FIG. 4), which will be described later, is disposed on the paper transport path Rt2 so as to face the separator 35.

The separator 35 is a plate portion 53 formed by extending in the paper conveyance path Rt1 in a direction orthogonal to the paper conveyance direction, that is, in the paper width direction, and in the width direction of the plate portion 53 (paper A plurality of locations in the width direction), which are formed by guide ribs 54 formed so as to project in the vertical direction, and between the upper edges eg1 of the guide ribs 54 and the guides 51, a space in which the paper is guided in the paper transport path Rt1, That is, the guide space Sp1 is formed, and the guide space Sp2 for guiding the paper in the paper transport path Rt2 is formed between the lower edge eg2 of each guide rib 54 and the guide 52.

It should be noted that δ1 is a conveyance path width for conveying the paper in the paper conveyance path Rt1.

By the way, the sheet on which the color toner image has been fixed by being heated and pressurized in the fixing device 31 is in a state in which the medium angle is curled downward (the side edges are low, and the central portion is curved so as to be high). ) Is sent to the separator 35.

In this case, the wide paper, that is, the wide paper PM, has a small curvature caused by the curl even when the color toner image is fixed and the medium angle is curled. Therefore, in the separator 35, both side edges egm of the wide paper PM. Does not interfere with the guide ribs 54, but narrow-width paper, for example, the narrowest paper used in the printer 10, that is, the narrow paper PN, has the color toner image fixed and the medium angle curls. Then, since the curvature caused by the curl is large, both side edges egn of the narrow paper PN may interfere with the guide ribs 54 in the separator 35, and in this case, the narrow paper PN cannot be smoothly conveyed.

Therefore, in the present embodiment, a slope portion 63 (FIG. 1) as a medium guiding portion, which will be described later, for correcting the curl generated in the paper and guiding the paper is formed at a predetermined position in the separator 35. ..

Next, the transport path switching mechanism M1 will be described.

1 is a perspective view of a main part of a transport path switching mechanism according to an embodiment of the present invention, FIG. 4 is a cross-sectional view showing the periphery of the transport path switching mechanism according to an embodiment of the present invention, and FIG. 5 is an embodiment of the present invention. FIG. 6 is a plan view of the transport path switching mechanism in FIG. 6, and FIG. 6 is a plan view of a main part of the transport path switching mechanism in the embodiment of the present invention.

In the figure, M1 is a conveyance path switching mechanism, Rt1 and Rt2 are paper conveyance paths, m3 and m5 are conveyance roller pairs, 35 is a separator, 43 is a conveyance roller pair m3 together with a pinch roller 44 (FIG. 2), Reference numeral 52 is a guide that is arranged so as to face the separator 35 in the paper transport path Rt2, PM is wide paper, and PN is narrow paper.

The separator 35 includes a plate portion 61 formed to extend in the width direction of the sheet conveyance path Rt1 (width direction of the sheet), and a plurality of positions in the width direction of the plate portion 61 (width direction of the sheet) in the vertical direction ( A guide rib 62, etc., which is formed so as to project in the vertical direction and supports the paper is provided.

Each of the guide ribs 62 has a triangular shape, and has an upper edge eg11 as a first edge extending along the sheet transport direction in the sheet transport path Rt1, and a sheet transport direction in the sheet transport path Rt2. A lower edge eg12 as a second edge extending along the side and a side as a third edge extending adjacent to the transport roller 43 and connecting the upper edge eg11 and the lower edge eg12. A rim eg13 is provided.

Then, in the central portion of the plate portion 61 in the width direction, by the number of four guide ribs 62-1 to 62-4 in the present embodiment, which corresponds to the paper width wn as the medium width of the narrow paper PN, A central guide portion Ar1 for guiding the narrow paper PN is formed.

In the central guide portion Ar1, two guide ribs 62-1 and 62-2 near the center among the guide ribs 62-1 to 62-4 have the same size as the other guide ribs 62 outside the central guide portion Ar1. In contrast to the guide ribs 62-1 to 62-4, the guide ribs 62-3 and 62-4 on both ends of the guide ribs 62-1 to 62-4 are formed smaller than the guide ribs 62-1 and 62-2. The upper edge eg11 of 62-4 is formed on the same surface as the upper edge eg11 of the guide ribs 62-1 and 62-2, and the side edges eg13 of the guide ribs 62-3 and 62-4 are the guide ribs in the sheet conveying direction. It is formed on the upstream side of the side edges eg13 of 62-1 and 62-2.

Then, actuators (not shown) for swinging the separator 35 are arranged at predetermined positions on both ends of the separator 35. The sheet sent from the fixing device 31 is driven to the actuator to pull the separator 35 downward to the first switching position and is sent to the sheet conveyance path Rt1 to push the separator 35 upward to move the sheet to the second position. When it is placed at the switching position, it is sent to the paper transport path Rt2.

Further, the transport roller 43 is attached to the shaft portion sh1 extending in the width direction of the sheet transport path Rt1 and rotatably disposed at a plurality of positions on the shaft portion sh1, and brought into contact with the pinch roller 44. And a paper feed gr1 attached to a shaft sh1 on the center side of a pair of central roller parts rp.

The paper feed gr1 is made of a rubber material and is composed of a rotating body having a plurality of teeth formed around it. The paper feed gr1 guides the paper when the paper is discharged to the auxiliary stacker.

Further, on both sides of the central guide portion Ar1, when the narrow paper PN is conveyed in the direction of the arrow in FIG. 6 in a state of being adjacent to the central guide portion Ar1, both side edges egn of the narrow paper PN are conveyed. And a pair of slope portions 63 for flattening the narrow paper PN are formed. The slope portion 63 is formed between the two guide ribs, that is, between the guide ribs 62-3 and 62-4 and the other guide rib 62, and is a portion where both side edges egn pass as the narrow paper PN is conveyed. The guide rib 62 is not formed.

The slope portion 63 is formed adjacent to the guide ribs 62-3 and 62-4, has a trapezoidal shape of the first guiding portion 65, and has a first guiding portion on both sides of the first guiding portion 65. The second guide portion 66 is formed adjacent to the guide roller 65 and has a rectangular shape. The first guide portion 65 is configured such that the conveying roller 43 and the pinch roller 44 that form the conveying roller pair m3 come into contact with each other. And the nip area formed by the sheet in the width direction of the sheet.

Further, the first guide portion 65 becomes lower as it gets closer to the central guide portion Ar1 and as it approaches the upstream edge of the paper transport path Rt1, that is, the leading edge eg21, and as it moves away from the central guide portion Ar1 (first It is formed so as to be inclined so as to become higher as it approaches the second guiding portion 66) and as it gets farther from the front edge eg21 (the edge on the downstream side in the paper transport path Rt1, that is, the rear edge eg22).

The second guide portion 66 is not tilted in the width direction of the sheet conveyance path Rt1, is lower as it approaches the leading edge eg23, and becomes higher as it goes away from the leading edge eg23 (as it approaches the trailing edge eg24). It is formed with an inclination.

Therefore, when the narrow paper PN is transported through the paper transport unit Rt1 and reaches the transport path switching mechanism M1, when the both side edges egn are on the first guiding unit 65, the narrow paper PN is transported. The curled side edges egn are gradually spread outward while being moved on the first guide portion 65 to be flattened. When both side edges egn of the narrow paper PN are on the second guide portion 66, the curled side edges egn are moved on the second guide portion 66 as the narrow paper PN is conveyed. While gradually spreading outward, it is made flat.

The rear edge eg22 of the first guide portion 65 and the rear edge eg24 of the second guide portion 66 have a smooth curved surface in order to guide both side edges egn of the narrow paper PN to the roller portion rp of the transport roller 43. Have. As a result, both side edges egn of the narrow paper PN guided by the slope portion 63 can be smoothly sent to the roller portion rp.

Further, when the angle of the front edge eg21 of the first guiding portion 65 with respect to the direction orthogonal to the sheet conveyance direction is θ, the angle θ is set to a large value within a range where it does not interfere with a component adjacent to the conveyance path switching mechanism M1. To be done. Therefore, when the narrow paper PN having the curled side edges egn reaches the transport path switching mechanism M1, the side edges egn can be placed on the first guiding portion 65.

Further, when the distance between the outer edges of the first guide portions 65 is set as the guide width wg, and when the guide width wg is made wider than the paper width wn of the narrow paper PN, both side edges egn of the narrow paper PN are It is reliably flattened while being moved over the first guide 65.

Then, for example, as shown in FIG. 5, the distance between both side edges egn of the narrow paper PN and the guide rib 62 (62-4) closest to the both side edges egn is set to Δwn, and both side edges of the wide paper PM are set. Assuming that the distance between the eggm and the guide rib 62 closest to the both side edges egm is Δwm, the distances Δwn and Δwm are
Δwn>Δwm
To be

Further, as described above, the upper edges eg11 of the guide ribs 62-3 and 62-4 are formed on the same plane as the upper edges eg11 of the guide ribs 62-1 and 62-2. Therefore, when the narrow paper PN reaches the transport path switching mechanism M1, both side edges egn of the narrow paper PN are supported on the guide ribs 62-3 and 62-4, so that the narrow paper PN is stabilized. Can be induced.

As described above, in the present embodiment, even if the both side edges egn of the sheet are curled, the both side edges egn of the sheet are interfered with the guide rib 62 because the both side edges egn of the sheet are flattened by the slope portion 63. There is nothing to do.

Therefore, it is possible to stably convey the sheet regardless of the width of the sheet, and it is possible to prevent the sheet from being bent or jammed.

In the present embodiment, the case where the sheet is sent to the separator 35 with the medium angle curled downward has been described. However, in the fixing device 31, the heating roller 32 is downward and the pressure roller 33 is upward. When placed, the sheet is sent to the separator 35 with the medium angle curled upward.

In that case, it is preferable to form a slope portion between the guide ribs 62-3 and 62-4 and the other guide ribs 62 on the side of the sheet conveyance path Rt2 in each guide rib 62.

Further, in the present embodiment, in the fixing device 31, the sheet is heated by the heating roller 32 and pressed by the pressure roller 33. However, the sheet is heated by the heating roller and the pressure roller. When a fixing device is installed, if the amount of paper heated by the heating roller is greater than the amount of paper heated by the pressure roller, the medium angle curls downward, and the amount of paper heated by the heating roller depends on the pressure roller. If the heating amount of the paper is smaller than the heating amount, the medium angle curls upward.

Therefore, when the heating amount of the sheet by the heating roller is larger than the heating amount of the sheet by the pressing roller, the heating amount of the sheet by the pressing roller is closer to the sheet conveyance path Rt1 side of each guide rib 62. If it is larger, it is preferable to form a slope portion on the sheet conveyance path Rt2 side of each guide rib 62.

Although the printer 10 has been described in the present embodiment, the present invention can be applied to an image forming apparatus such as an MFP, a facsimile, and a copying machine.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

35 Separator 61 Plate part 62, 62-1 to 62-4 Guide rib 63 Slope part Ar1 Central guide part egn Both side edges PN Narrow paper wn Paper width

Claims (9)

(A) a plate portion formed to extend in the width direction of the medium,
(B) having guide ribs formed at a plurality of positions in the width direction of the plate portion,
(C) A central guide portion is formed at the central portion in the width direction of the plate portion by a number of guide ribs corresponding to the medium width of the medium having the minimum width,
(D) A medium transport guide, wherein medium guiding portions for guiding both side edges of the medium to flatten the medium are formed on both sides of the central guiding portion. The medium transport guide according to claim 1, wherein the medium guiding portion is formed between two guide ribs. 2. The distance between both side edges of the medium having the minimum width and the guide ribs closest to the both side edges is longer than the distance between both side edges of the medium having the maximum width and the guide ribs closest to the both side edges. Alternatively, the medium transport guide described in 2. A nip region formed between two rollers of a pair of transport rollers for transporting the medium, which is disposed on the downstream side of the medium transport guide in the transport direction of the medium, and the medium guiding portion, are arranged in the width direction of the medium. The medium conveyance guide according to claim 1, wherein the medium conveyance guide is overlapped. 5. The medium transport guide according to claim 1, wherein the medium guiding portion is formed so as to be lower as it approaches an upstream edge in the medium transport direction and higher as it is farther from the upstream edge. .. (A) The medium guiding part includes a first guiding part formed on both sides of the central guiding part, and second guiding parts formed on both sides of the first guiding part.
(B) The medium transport guide according to claim 5, wherein the first guide portion is formed so as to be lower as it approaches the central guide portion and higher as it is farther from the central guide portion. An image forming apparatus provided with the medium transport guide according to any one of claims 1 to 6. The image forming apparatus according to claim 7, wherein the fixing device is disposed on the upstream side of the medium transport guide in the medium transport direction. (A) a first medium transport path for transporting a medium,
(B) having a second medium carrying path formed by branching from the first medium carrying path,
(C) The image forming apparatus according to claim 7 or 8, wherein the medium conveying guide is arranged so as to be swingable and sends the medium sent from the fixing device to the first medium carrying path or the second medium carrying path. apparatus.

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