JP2004323137A - Paper delivery device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent erroneous detection of a paper delivery sensor due to the contact of paper after delivery with the paper delivery sensor and prevent delivered paper from being caught in a device by a paper delivery roller even when curled paper is delivered on a paper delivery tray. <P>SOLUTION: This paper delivery device X is provided with a pair of upper and lower rollers (paper delivery rollers 41) for delivering paper onto the paper delivery tray outside the device from the inside of an image formation device, the paper delivery sensor 52 for detecting a delivery condition of paper due to a displacement condition of a displacement lever 51 displaced by the contact with the paper during delivery, and a cover member 53 provided in a lower part more than a paper delivery position 41b of the paper delivery roller 41 to prevent the contact of the paper delivered on the paper delivery tray with the displacement lever 52 and a lower side roller 41a of the paper delivery roller and provided with a projecting curved face 53a in the direction of the paper delivery tray. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a paper discharge device having a paper discharge sensor for detecting a paper discharge state when paper is discharged from the inside of an image forming apparatus to a paper receiving portion outside the apparatus, and an image forming apparatus having the same. is there.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in an image forming apparatus such as a front-access type copying machine that reduces the area occupied by the apparatus, a paper feeding unit disposed at a lower part of the apparatus and a document reading unit disposed at an upper part of the apparatus are provided. A type that discharges the printed paper to a paper receiving unit (discharge unit) disposed between them has been developed. In such an image forming apparatus, the paper stacking height of the paper receiving section is greatly restricted, and the number of dischargeable sheets is relatively small.
For this reason, a paper ejection sensor provided in such an image forming apparatus is provided with a paper ejection sensor near the paper ejection port, which detects the completion of ejection of the paper and the number of sheets ejected to the paper receiving unit. Function to detect the paper discharge (stacking) state to the paper receiving section by counting the number of sheets, and to notify the user when the paper receiving section becomes full (upper stack number). Have been.
FIG. 5 is a schematic cross-sectional view of a conventional sheet discharging device A, in which FIG. 5A shows a state after the sheet is completely discharged, and FIG. 5B shows a state during the sheet discharging.
The conventional paper discharging device A includes a pair of upper and lower paper discharging rollers 41 (paper discharging driven roller 41b and paper discharging driving roller 41a) which are paper discharging means for discharging paper from inside the image forming apparatus to a paper receiving portion outside the apparatus. , A displacement lever 51 (displacement member) that is displaced (rotated) by coming into contact with the paper being discharged, and a photo sensor 52 that detects a displaced state (rotated state) of the displacement lever 51.
In a normal state (a state in which the sheet S is not being discharged), the displacement lever 51 is located at a position P0 (hereinafter, referred to as a reference position) shown in FIG. 5B, the sheet S is displaced by contact with the sheet S being discharged as shown in FIG. 5B. By detecting the displacement state of the displacement lever 51 at this time by the photo sensor 52, it is detected that the sheet S is being ejected and that the ejection of the sheet is completed (the displacement lever 51 and the The photo sensor 52 constitutes a paper ejection sensor).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 02-270762
[Problems to be solved by the invention]
However, in the image forming apparatus of the type described above, the paper is transported from a substantially horizontal state in the paper feed unit to a substantially vertical direction and then discharged in a substantially horizontal direction, followed by a substantially U-shaped curved transport path. Since the sheet is conveyed, the sheet is often discharged in a curled state (curved state). In particular, when the paper contains a large amount of moisture, curling is more likely to occur due to a large amount of evaporated water on the image surface side when the image on the paper is heated and fixed.
When the paper is discharged in a curled state, the curled portion of the paper after the paper discharge is completed comes into contact with the displacement lever 51 (displacement member) and is displaced (pushed up) as shown in FIG. As a result, there is a problem in that the completion of discharge of the sheet cannot be detected, and the occurrence of a paper jam (JAM) is erroneously detected. Further, as shown in FIG. 6B, the curled portion of the sheet comes into contact with the lower sheet discharging roller (in the example shown in FIG. 6, the sheet discharging gallery roller 52a), and the discharged sheet is entangled in the apparatus. There was also a problem that it was.
On the other hand, in Patent Document 1, when a curled sheet is ejected to a sheet ejection tray (sheet receiving section), the curled section of the sheet pushes up (contacts) a detection lever, and the sheet is ejected to the sheet ejection tray. A discharge overflow detection method for preventing erroneous detection of fullness of a sheet before the number of stacked sheets reaches a predetermined set number is shown.
However, the detection lever for detecting the height of the paper loaded on the paper receiving portion is a relatively large member, and providing such a paper full (overflow) detection means together with the paper discharge sensor is difficult. In an image forming apparatus that requires miniaturization, there is a problem that it cannot be used in terms of space.
Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to allow a discharged sheet to detect a discharged state even when a curled sheet is discharged to a sheet receiving portion. Provided is a paper discharge device for preventing a paper discharge sensor from erroneously detecting a paper sensor when the paper discharge sensor comes into contact with the paper sensor, and preventing a discharged paper from being caught in the device by a paper discharge roller, and an image forming apparatus including the same. It is in.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a sheet discharging means for discharging a sheet from the inside of an image forming apparatus to a sheet receiving portion outside the apparatus, and a sheet displacing member which is displaced by coming into contact with the sheet being discharged. And a discharge sensor for detecting a discharge state of the sheet, wherein a cover member is provided for blocking a sheet discharged to the sheet receiving portion from contacting the displacement member. As a paper discharge device.
Thus, even if the curled sheet is discharged, it is possible to prevent the curled portion (the rear end of the sheet) of the sheet from contacting the displacement member and displacing it, and the discharge sensor is provided with a rearward position. Detection (malfunction) can be prevented.
[0006]
Further, if the cover member is provided below a position where the sheet is discharged by the sheet discharging means and has a curved surface that is convex in the direction of the sheet receiving portion, the cover member may discharge the sheet. Further, the rear end (the downstream end in the discharge direction) of the discharged sheet slides on the curved surface and falls smoothly onto the sheet receiving portion without obstructing the sheet.
[0007]
Further, the paper discharge means includes a pair of upper and lower discharge rollers, and the cover member also prevents the paper discharged to the paper receiving portion from contacting a lower roller of the discharge roller pair. If the sheet is discharged, it is possible to prevent the discharged sheet from being caught in the apparatus by the lower roller.
Here, if the cover member is formed with a cutout portion through which the displaceable displacement member is passed, a single (integral) cover member can cover a predetermined range over both sides in the displacement direction of the displacement member. In this case, the contact of the sheet with the displacement member can be blocked.
Further, the present invention may be regarded as an image forming apparatus provided with the paper discharging device.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings to facilitate understanding of the present invention. The following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention.
Here, FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus provided with a paper discharge device X according to the embodiment of the present invention, and FIG. 2 is a perspective view of the paper discharge device X according to the embodiment of the present invention. FIG. 3 is a perspective view showing a structure of attaching and detaching a cover member constituting a sheet discharging device X according to an embodiment of the present invention to a shaft of a sheet discharging roller, and FIG. 4 is a sheet discharging device according to an embodiment of the present invention. 5 is a schematic cross-sectional view of a conventional paper discharging device A, and FIG. 6 is a cross-sectional view showing a state in which curled paper is discharged by the conventional paper discharging device A.
[0009]
First, an image forming apparatus 1 including a paper discharge device X according to an embodiment of the present invention will be described with reference to the cross-sectional view of FIG.
The image forming apparatus 1 has a copier mode (copy mode), a printer mode, and a facsimile mode as print modes, and receives an operation input from an operation unit (not shown) or a print job from an external host device such as a personal computer. Is selected by a control unit (not shown).
As shown in FIG. 1, the image forming apparatus 1 is roughly divided into a document reading unit 10 (document reading unit), a sheet feeding unit 20 (sheet feeding unit), a printing unit 30 (printing unit), and a sheet discharging unit 40. The document reading unit 10 is provided above the paper feeding unit 20, and the paper discharging unit 40 is provided at an intermediate portion between the document reading unit 10 and the paper feeding unit 20.
The copier mode among the above processing modes will be described below.
After the original is placed on the platen glass 11 of the original reading unit 10 (scanner unit), the user mounts the paper on the paper feed cassette 21 of the paper feed unit 20 and operates the operation panel disposed on the front surface of the exterior of the apparatus. After inputting the above condition input keys (number of prints / print magnification, etc.) (not shown), operating the start key on the operation panel starts the copy operation.
When the start key is operated, a main drive motor (not shown) starts, and each drive gear rotates. Thereafter, the paper feed roller 22 rotates to feed the paper, and the fed paper reaches the registration roller 31. The registration roller 31 temporarily suspends the sheet to synchronize with the leading end of the image formed on the photosensitive drum 32 (image forming start portion), and uniformly presses the leading end of the sheet against the registration roller 31. Then, the leading end position of the sheet is corrected.
On the other hand, in the document reading section 10, the exposure starts when the copy lamp 12a (light source) is turned on and the copy lamp unit 12 moves in the direction of the arrow. Irradiation light applied to the original by the copy lamp 12a becomes reflected light (reflected light from the original) including image information of the original, and the reflected light is transmitted from a first mirror 12b provided on the copy lamp unit 12 to a second mirror 12b. The image is read by being input to the CCD 16 from the mirror 13, the third mirror 14, and the optical lens 15.
The image information read in this way is converted into an electric signal by a CCD circuit provided in a control unit (not shown), and the image information signal is subjected to image processing under set conditions. , LSU unit 33 as print data.
On the other hand, the entire photosensitive drum 32 is charged to a predetermined charging potential by the charging unit 34. The laser light from the LSU unit 33 is irradiated to the photosensitive drum 32 through a polygon mirror and various lenses (not shown), and an electrostatic latent image is formed on the photosensitive drum 32. Thereafter, the toner on the MG roller 35s in the developing tank 35 is attracted to the surface of the photosensitive drum 32, and the electrostatic latent image is visualized by the toner according to the potential gap on the photosensitive drum 32.
The sheet (sheet material) on which an image is formed is conveyed toward the photosensitive drum 32 by the registration roller 31 at a proper timing, and the toner on the photosensitive drum 32 is transferred to the sheet by the transfer unit 36 (corona charger). Is done. The toner remaining on the photosensitive drum 32 is scraped off by the cleaning blade 37a of the drum unit, and is collected by the cleaner unit 37.
On the other hand, the sheet on which the transfer of the toner has been completed passes through the upper heat roller 38a and the lower heat roller 38b of the fixing device 38 (fixing step), and heat and pressure are applied thereto. The sheet is fixed and discharged to the sheet discharge tray 42 by the sheet discharge rollers 41 constituting the sheet discharge device X.
[0010]
FIG. 2 is a perspective view illustrating a configuration of the sheet discharging device X.
The paper discharge device X according to the embodiment of the present invention, like the conventional paper discharge device A (see FIG. 5), transfers a sheet from the inside of the image forming apparatus 1 to a paper discharge tray 42 (paper receiving portion) outside the apparatus. A pair of upper and lower paper discharge rollers 41 (paper discharge driven roller 41b and paper discharge drive roller 41a) serving as a paper discharge means to be discharged, and a displacement lever 51 (displacement member) which is displaced (rotated) by contacting the paper being discharged. ) And a photo sensor 52 for detecting the displacement state (rotation state) of the displacement lever 51. The paper discharge driven roller 41b is elastically urged by a spring with respect to the paper discharge drive roller 41a in order to discharge the paper sandwiched between the paper discharge drive roller 41a and the paper discharge drive roller 41a.
The present paper discharging apparatus X differs from the conventional paper discharging apparatus in that a cover member 53 is provided to block the paper discharged to the paper discharging tray 42 from contacting the displacement lever 51.
The cover member 53 is provided below a position where the paper is discharged by the paper discharge roller 41 (the nip portion 41d of the roller pair), and is arranged so as not to hinder the paper discharge. Here, as shown in FIG. 3, the cover member 53 is configured to be detachable from a rotation shaft 41c of the paper ejection drive roller 41a by a snap-stop mechanism. This makes it easy to assemble the device, and can be easily removed at the time of maintenance or the like, thereby facilitating maintenance work.
Further, the cover member 53 is formed with a notch 53b through which the displacement lever 51 passes so as not to hinder the displacement operation (rotational operation) of the displacement lever 51. Here, one (integral) cover member 53 prevents the discharged sheet from contacting the displacement lever 51 in a certain range on both sides of the displacement path of the displacement lever 51. The notch portion 53b is provided in the cover member 53 over the predetermined range. For example, separate (plural) cover members (the displacement of the sheet after discharging) are provided on both sides in the displacement direction of the displacement lever 51. It is also conceivable to adopt a configuration in which a cover member that blocks contact with the lever 51 is provided. Further, a certain effect can be obtained only by providing a cover member on one side of the displacement lever 51. Further, the cover member 53 has a curved surface 53a that is convex in the direction of the paper discharge tray 42 (not shown in FIG. 2).
[0011]
FIG. 4 is a schematic sectional view of the sheet discharging device X.
The cover member 53 protrudes toward the discharge tray 42 beyond the displacement lever 51 and the discharge roller 41, so that the sheet discharged to the discharge tray 42 is moved by the displacement lever 51 and the discharge lever 51. It is configured to block contact with the paper ejection drive roller 41a (lower roller).
For this reason, even when the curled sheet is discharged to the discharge tray 42, the discharged sheet contacts (lifts) the displacement lever 51 and is erroneously detected as having JAM, or the discharged sheet is discharged. It is possible to prevent the discharged paper from being caught in the apparatus by the paper discharge drive roller 41a.
Further, since the curved surface 53a is formed, the curved surface 53a functions as a paper guide, and the trailing end of the discharged paper (the downstream end in the paper discharging direction) is curved. Since the paper 53 slides on the surface 53a and smoothly falls to the paper discharge tray 42 side, paper jam is less likely to occur.
[0012]
【The invention's effect】
As described above, according to the present invention, in a sheet ejection device including a sheet ejection sensor that detects a sheet ejection state when ejecting a sheet to a sheet receiving unit, the sheet ejected to the sheet receiving unit A cover member is provided to block the paper from coming into contact with the displacement member of the paper ejection sensor. Therefore, even if the curled paper is ejected to the paper receiving section, the ejected paper comes into contact with the displacement member and the paper ejection sensor malfunctions. Detection can be prevented, and stable paper ejection detection can be realized. Further, the cover member also prevents the discharged paper from contacting the paper discharge roller, thereby preventing the discharged paper from being caught in the apparatus by the paper discharge roller.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus including a paper discharge device X according to an embodiment of the present invention.
FIG. 2 is a perspective view of a paper discharge device X according to the embodiment of the present invention.
FIG. 3 is a perspective view showing a structure of attaching and detaching a cover member included in the sheet discharging device X according to the embodiment of the present invention to a shaft of a sheet discharging roller.
FIG. 4 is a schematic cross-sectional view of a paper discharge device X according to the embodiment of the present invention.
FIG. 5 is a schematic sectional view of a conventional sheet discharging device A.
FIG. 6 is a cross-sectional view illustrating a state where a curled sheet is discharged by a conventional sheet discharging device A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Image reading part 20 ... Paper supply part 30 ... Printing part 31 ... Registration roller 32 ... Photoconductor drum 34 ... Charging unit 35 ... Developing tank 36 ... Transfer unit 38 ... Fixing device 40 ... Paper discharge part 41 ... Paper discharge rollers (paper discharge means)
41a: paper ejection drive roller (lower roller)
41b: paper discharge driven roller 41c: rotating shaft 42 of paper discharge drive roller ... paper discharge tray (paper receiving part)
51: Displacement lever (displacement member)
52 Photosensor (paper ejection sensor)
53 ... Cover member 53a ... Curved surface 53b of cover member ... Cut of cover member

Claims (5)

A sheet discharging means for discharging a sheet from the inside of the image forming apparatus to a sheet receiving portion outside the apparatus; a sheet discharging sensor for detecting a sheet discharging state based on a displacement state of a displacement member which is displaced by contacting the sheet being discharged; , A paper ejection device having
A sheet discharging device, comprising: a cover member that blocks a sheet discharged to the sheet receiving portion from contacting the displacement member. 2. The sheet discharging device according to claim 1, wherein the cover member is provided below a position where the sheet is discharged by the sheet discharging unit, and has a curved surface that is convex in a direction of the sheet receiving portion. The sheet discharge means includes a pair of upper and lower discharge rollers;
3. The sheet discharging device according to claim 1, wherein the cover member also prevents the sheet discharged to the sheet receiving portion from contacting a lower roller of the pair of discharging rollers. The sheet discharging device according to any one of claims 1 to 3, wherein the cover member has a cutout portion through which the displaceable displacement member passes. An image forming apparatus comprising the sheet discharging device according to claim 1.

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