JP2008030912A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-body paper delivery type image forming device capable of improving visibility and taking out performance of paper sheets on a delivery tray by a simple configuration and of stably stacking paper sheets. <P>SOLUTION: Paper sheets P' delivered on the paper delivery tray 23 are slipped down forwardly (left direction in Fig. 4) along a gradient of a paper stacking face 23a, and the side end parts of the paper sheets P' are aligned by a drop-out prevention stopper 60. The drop-out prevention stopper 60 is provided movably in the front and back directions (right and left directions in Fig. 4) along the paper stacking face 23a. The drop-out prevention stopper 60 is moved by predetermined amount to the device back side (right direction in Fig. 4) such that the side end part in the device front side of the drop-out prevention stopper 60 is overlapped with the side end parts in the device back side of already stacked paper sheets P' (broken line in the figure) in accordance with the size of the paper sheets P'. Due to this structure, since the paper sheets P' are smoothly slipped down along the stacked paper sheets P', irregularity of the stacking state in the front and back directions of the device can be prevented even when small-sized paper sheets are continuously delivered. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an in-cylinder discharge type image forming apparatus in which a discharge section space is provided in an apparatus main body between an image reading section and an image forming section. The present invention relates to an improvement in visibility and take-out property of paper on a discharge tray.

  2. Description of the Related Art Conventionally, in an image forming apparatus represented by a copying machine or a fax machine, a so-called in-cylinder discharge in which a paper discharge unit space is arranged inside the image forming apparatus main body in order to eliminate a protruding portion as much as possible and achieve a compact structure. A paper mechanism has been proposed.

  Specifically, an image reading unit (scanner unit) is provided above an image forming unit that forms a toner image on the surface of the photosensitive drum by electrophotography, and paper feeding is performed for supplying paper to the image forming unit. It is provided at a position below the forming unit, and a toner image is fixed between the image forming unit and the image reading unit, and a paper discharge unit for storing the discharged paper is formed as an in-body discharge space. In an image forming apparatus having such a cylinder discharge space, a sheet discharge tray is usually provided at the bottom of the cylinder discharge space.

  The configuration of a conventional in-body discharge type image forming apparatus is shown in FIGS. FIG. 6 is a perspective view showing an external configuration of the image forming apparatus, and FIG. 7 is a right side view of the image forming apparatus. In FIG. 6, an image forming apparatus 100 is a so-called in-cylinder discharge type digital copying machine, and generally includes a main body housing 20 and an upper housing 21 disposed on an upper portion thereof. The upper housing 21 is provided with an image reading unit for reading an image of an original as an electric signal. On the other hand, an image is formed on a sheet in the main body housing 20 based on the electric signal of the read original image. Various mechanisms are provided.

  The main body housing 20 is composed of a lower housing 20a and a connecting housing 20b that is positioned along the upper left side and connected to the upper housing 21. The lower housing 20a includes a paper feed mechanism that feeds paper. In addition, an image forming unit for forming a toner image on the paper, a fixing unit for fixing the toner image on the paper, and the like are provided. On the other hand, the connected housing 20b is used for conveying and discharging the fixed paper. The paper discharge section is provided.

  A cylinder discharge space 22 is formed on the right side of the connecting housing 20b immediately below the upper housing 21 and is open to the right side and the front of the apparatus. Is provided with a paper discharge tray 23 for receiving and stacking paper discharged horizontally from a paper discharge port 24 provided on the right side surface of the connecting housing 20b. A paper cassette 40 that stores various sizes of paper and can be taken in and out from the front is disposed in the lower portion of the lower housing 20a. The lower housing 20a is pulled down as needed on the lower left side of the lower housing 20a. An openable and closable manual paper tray 41 is provided.

  On the upper surface of the upper housing 21, there are disposed a document placing table (not shown) made of a transparent glass plate and an operation panel 26 protruding to the front side of the apparatus. Further, above the upper housing 21, a document presser 28 equipped with a document transport device 27 for transporting a document to an image reading position on the document mounting table is openable and closable by a hinge portion 21 a fixed to the back surface of the upper housing 21. It is supported by. That is, as shown in FIG. 7, the document presser 28 is closed with respect to the upper housing 21 to perform a document reading operation (solid line in the drawing), and opened with respect to the upper housing 21 (in the drawing). (Dashed line).

  In such an image forming apparatus, an image reading unit, an operation panel, and a document table are provided in the upper part of the apparatus. Therefore, when taking out the paper discharged to the in-body discharge space 22, the paper discharge tray 23 is operated by the operation panel or the like. Hiding, and depending on the paper size, it is difficult to see the paper from above and take it out. In addition, for example, when the image forming apparatus is arranged near the desk and the image forming apparatus is operated while sitting on a chair or used by a wheelchair worker, the paper on the paper discharge tray 23 from the front of the image forming apparatus. The situation was the same in this case as well.

  In view of this, a method for improving the visibility of the paper discharged into the in-body discharge space of the image forming apparatus and facilitating the removal is proposed, and Patent Documents 1 and 2 disclose a paper discharge tray on the front side of the apparatus. A method is disclosed in which the paper is collected toward the front side of the apparatus by inclining the paper toward the front of the apparatus so that the paper can be easily taken out from the paper discharge tray, and a method in which the paper discharge tray can be pulled out forward when the paper is taken out. Yes.

However, when the paper discharge tray is tilted toward the front of the machine, depending on the relationship between the paper size and the paper discharge reference position, the side edge of the discharged paper may interfere with the side edge of the already discharged paper. As a result, the paper does not slide down smoothly and the paper may not be stably stacked on the paper discharge tray. Further, in the case of a method of pulling out the paper discharge tray, when a large amount of paper is stocked on the tray, the weight of the paper becomes heavy and workability is deteriorated.
Japanese Patent Laid-Open No. 5-116830 JP-A-7-267468

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an in-cylinder discharge type image forming apparatus that can improve the visibility and take-out performance of sheets on a sheet discharge tray with a simple configuration and can stably stack sheets. For the purpose.

  In order to achieve the above object, the present invention provides a paper feeding device, an image forming unit that is disposed above the paper feeding device and forms an image on paper fed from the paper feeding device, and the image forming unit An image reading unit arranged above the image reading unit for reading a document image, a sheet discharge port provided on a side surface of a cylinder discharge space provided between the image reading unit and the image forming unit, and the cylinder discharge. A paper discharge tray disposed on a bottom surface of the paper space, wherein the paper discharge tray is an in-cylinder discharge type image forming apparatus that discharges paper after image formation from the paper discharge port onto the paper discharge tray. The paper stacking surface that receives the ejected paper has a downward slope from the back of the device to the front, and a drop-off prevention stopper that prevents the paper from dropping off is moved forward and backward on the front side of the paper stacking surface. It is characterized by being possible.

According to the present invention, in the image forming apparatus configured as described above, when the minimum distance from the center in the width direction of the paper discharged from the paper discharge port to the drop-off prevention stopper is D, and the minimum paper width to be discharged is Wmin. The following conditional expression (1) is satisfied.
D <1.5 Wmin (1)

According to the present invention, in the image forming apparatus configured as described above, when the minimum distance from the center in the width direction of the paper discharged from the paper discharge port to the drop-off prevention stopper is D, and the minimum paper width to be discharged is Wmin. The following conditional expression (2) is satisfied.
Wmin <D <1.5Wmin (2)

  According to the present invention, in the image forming apparatus configured as described above, the sheet stacking surface has an upward slope in the sheet discharge direction.

  According to the first configuration of the present invention, even when paper is discharged with reference to the center in the width direction of the paper discharge port, the paper collects on the front side of the paper discharge tray, and the discharged paper is visible from above and from the front. And the paper can be easily taken out. In addition, by providing the stopper to be able to move back and forth, the stopper can be moved to a position where the side edge of the discharged paper does not interfere with the already discharged paper, and the width of the discharged paper Regardless of whether the paper can be stacked stably.

  According to the second configuration of the present invention, in the image forming apparatus having the first configuration, the minimum distance D from the center in the width direction of the sheet discharged from the sheet discharge port to the drop-off prevention stopper is discharged. When the minimum sheet width Wmin satisfies the conditional expression (1), the stacking state in the front-rear direction of the apparatus is not disturbed even when sheets of the minimum size are continuously discharged.

  According to the third configuration of the present invention, in the image forming apparatus having the second configuration, the minimum distance D from the center in the width direction of the sheet discharged from the sheet discharge port to the drop-off prevention stopper is discharged. When the minimum paper width Wmin satisfies the conditional expression (2), the disturbance of the stacking state is prevented while maintaining the visibility of the paper and the ease of taking out when the paper of the minimum size is continuously discharged. be able to.

  According to the fourth configuration of the present invention, in the image forming apparatus having any one of the first to third configurations, the discharged sheet is provided with an upward slope in the sheet discharge direction of the sheet stacking surface. Are stacked in one place without variation in the discharge direction, so that it becomes easier to take out the paper from the paper discharge tray.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view showing the internal configuration of the image forming apparatus of the present invention. Portions common to FIGS. 6 and 7 of the conventional example are denoted by the same reference numerals and description thereof is omitted. First, a document conveying operation by the document through type document conveying unit 27 will be described with reference to FIG.

  In the paper-through type document conveying operation, first, a plurality of documents set with the image surface facing upward on the document feeding tray 29 are set by a set document pressing member 37 biased upward by a spring member 37a. Is pressed against the pickup roller 32 by the pressure of. Here, when the copy start button on the operation panel 26 (see FIG. 6) is turned on, the pickup roller 32 and the conveyance roller pair 33 are rotationally driven by the primary paper feed driving means (not shown).

  The document set on the document feed tray 29 is normally fed by the pickup roller 32 to the upper pair of transport rollers 33. The plurality of originals sent to the conveyance roller pair 33 are separated by the separation roller 33b and are conveyed toward the registration roller pair 34 after being separated by the separation roller 33b. At that time, after the leading edge of the document is detected by the sheet feeding sensor S2, the document is conveyed by a predetermined distance, and then the driving roller 33a and the pickup roller of the conveying roller pair 33 are stopped by the operation of the primary sheet feeding driving means. The rotational drive of 32 is stopped and the primary paper feeding ends. The original of the primary paper feed is stopped in a state where the front end is pressed against the nip portion of the registration roller pair 34 and the front end is bent.

  Secondary feeding is started after a lapse of a predetermined time from completion of primary feeding. That is, the registration roller pair 34 is rotationally driven by the operation of the secondary paper feed driving means (not shown). The document is conveyed by the registration roller pair 34 to the discharge roller pair 35 through the image reading position R, and finally discharged onto the document discharge tray 31 by the discharge roller pair 35. At this time, the completion of image reading of one original is detected by detecting the passage of the rear end of the original by the discharge sensor S3.

  Here, the discharge sensor S3 has a counting function that counts the number of documents every time the document feed and conveyance is completed. If the document detection sensor S1 detects a subsequent document, the second and subsequent document conveyance is performed. Will continue as above. When the document passes through the image reading position R, the document is conveyed while being lightly pressed toward the document placing table 25 by the white reference plate 36 and the document pressing portion 36a, and the image of the document is read through the image reading position R. It is supposed to be.

  Next, a configuration of an image reading unit provided in the upper housing 21 for reading an image of a document as an electric signal will be described. In the upper housing 21, a lamp 1 that is a light source that irradiates light toward the image surface of the document, a reflector 2 that efficiently applies light from the lamp 1 to the image surface of the document, and document reflected light The first mirror 3 that directly receives and reflects the light, the second mirror 4 that receives and reflects the reflected light from the first mirror 3, and the third mirror that receives and reflects the reflected light from the second mirror 4 5 and a lens barrel 6 that holds a lens group (not shown) that introduces and collects reflected light from the third mirror 5, and receives document reflected light collected by the lens group of the lens barrel 6. A photoelectric conversion module (for example, a line-type CCD) 7 for converting to an electrical signal is disposed on the base plate 10. The optical path of the original reflected light is indicated by a one-dot chain line.

  Here, the lamp 1, the reflector 2 and the first mirror 3 are integrally fixed on the first carriage 8, and the second mirror 4 and the third mirror 5 are integrally fixed on the second carriage 9. The first carriage 8 and the second carriage 9 are independent of each other but can be reciprocated in cooperation. That is, when the original image reading operation is performed by the paper through method, the first carriage 8 is moved and held immediately below the image reading position R, and the second carriage 9 is held at a predetermined position. On the other hand, in the original fixing method, the first carriage 8 and the second carriage 9 reciprocate (scan) while maintaining the optical path length of the original reflected light constant.

  Under such a configuration, the document reflected light irradiated from the lamp 1 and reflected by the image surface of the document is reflected by the first mirror 3 to the third mirror 5 and introduced into the lens group in the lens barrel 6. The light is condensed by the lens group and imaged on the photoelectric conversion element of the photoelectric conversion module 7. The photoelectric conversion module 7 performs photoelectric conversion processing, and the document image is read as an electric signal.

  Next, the configuration of various mechanisms provided in the main body housing 20 for transferring an image to a sheet based on an electric signal of the read document image will be described. First, the paper feeding unit will be described. The paper (transfer paper or OHP sheet) P stored in the paper feed cassette 40 is sent out one by one by the feeding roller 40a. Further, the paper P ′ set in the manual paper tray 41 is sent out one by one by the feeding roller 41a.

  Next, an image forming unit for forming a toner image on a sheet and a fixing unit for fixing the toner image on the sheet will be described. Above the paper feed cassette 40 in the lower housing 20a, a photosensitive drum 42 constituting a main image forming unit, a charging device 43, a laser exposure unit 44, a developing device 45, A transfer roller 46 and a cleaning device 47 are provided. A fixing device 48 is disposed in the lower housing 20a above the transfer roller 46 and directly below the connecting housing 20b.

  The photosensitive drum 42 is made of, for example, positively chargeable amorphous silicon, and rotates clockwise in FIG. 3 at a predetermined peripheral speed when driven. The surface of the photosensitive drum 42 is uniformly charged by corona discharge generated from the charging device 43 to which a high voltage is applied, and then the laser exposure unit 44 based on the electrical signal of the original image from the photoelectric conversion module 7 described above. The electrostatic latent image composed of a predetermined light potential and dark potential portion is formed by the irradiation of the light beam from.

  Further, the electrostatic latent image rotates to the developing position by the rotation of the photosensitive drum 42. The developing roller 45a, which is a component of the developing device 45, is made of, for example, stainless steel and has a fixed magnet inside. The developing roller 45a is rotatably supported with a predetermined gap from the photosensitive drum 42, and is the same as the photosensitive drum 42 when driven. Rotate in the direction with a predetermined peripheral speed. The developing device 45 is filled with, for example, a positively charged magnetic toner having a volume average particle diameter of 9 μm (median diameter measured by a Coulter counter), and a toner thin film is formed on the surface of the developing roller 45a by a magnetic blade (not shown). A layer is formed. A predetermined developing bias voltage is applied to the developing roller 45a. The toner that has reached the developing region flies from the surface of the developing roller 45a by the developing bias voltage, and is attracted to the electrostatic latent image on the surface of the photosensitive drum 42, thereby forming (developing) a toner image.

  Here, the toner image on the photosensitive drum 42 is transferred to the transfer roller 46 on the paper P (or the paper P ′) that has been fed out from the paper feed cassette 40 (or the manual paper tray 41) one by one and reaches the registration roller pair 49. In synchronism with the movement of the toner, the registration roller pair 49 feeds the sheet upward while the conveyance timing is adjusted, and is conveyed between the photosensitive drum 42 and the transfer roller 46 through the conveyance path T1. Then, most of the toner in the toner image is transferred onto the paper P when the leading edge of the paper P and the leading edge of the toner image pass through the transfer roller 46.

  The toner remaining on the surface of the photosensitive drum 42 without being transferred onto the paper P is removed from the photosensitive drum 42 by the cleaning device 47. On the other hand, the paper P on which the toner image is transferred is sent to the fixing device 48. The fixing device 48 has a pair of fixing rollers composed of a heat roller 48a and a pressure roller 48b, and the toner image on the paper P passing through the nip of each other is heated and pressed by the pair of fixing rollers to be fixed. As a result, a fixed transfer image is formed on the paper P.

  The sheet P that has passed through the fixing device 48 is conveyed into the connecting housing 20b along the conveying path T2 that is directed vertically upward. In this connection housing 20b, a conveyance roller pair 50 connected to the conveyance path T2 and a discharge roller pair 51 for discharging the paper P to the paper discharge tray 23 are disposed. The paper P sent out from the conveyance roller pair 50 reaches the discharge roller pair 51 through the conveyance path T3, and is discharged from the discharge roller pair 51 through the paper discharge port 24 to the paper discharge tray 23.

  The paper stacking surface 23a of the paper discharge tray 23 has a downward slope from the back side of the apparatus to the front side (from the back side of the paper surface in FIG. 1 to the front side) and an upward slope in the discharge direction (right direction in FIG. 1). The paper stacking surface 23a is provided on the front side of the sheet stacking surface 23a with a slip-off preventing stopper 60 for preventing the slipping of the sheet so as to be movable along the sheet stacking surface 23a in the front-rear direction (paper surface direction in FIG. 1). Yes.

  FIG. 2 is a side sectional view of the image forming apparatus that discharges a large size sheet (cross section AA ′ in FIG. 1), and FIG. 3 is a plan view of the sheet discharge tray in the in-cylinder discharge space (BB ′ in FIG. 2). Cross section). As shown in FIGS. 2 and 3, the paper P discharged onto the paper discharge tray 23 slides forward (leftward in FIG. 2, downward in FIG. 3) along the gradient of the paper stacking surface 23a and drops off. The side ends are aligned by the prevention stopper 60.

  With this configuration, even when paper is discharged with the center in the width direction of the paper discharge port 24 as a reference (center reference), the paper is collected on the front side of the paper discharge tray 23, and the visibility of the discharged paper from above the apparatus is improved. At the same time, the paper can be easily taken out. Further, since the sheets are stacked in a state inclined forward, the visibility from the front of the apparatus is also improved.

  Further, since the paper stacking surface 23a has an upward slope in the discharge direction (right direction in FIG. 3), the paper P slides down to the left in FIG. 3 along the slope and aligns the rear end portion by the rear wall portion 23b. Then, the sheets are sequentially stacked at the front left corner of the paper discharge tray 23 (the broken line position in FIG. 3). Accordingly, the discharged sheets are stacked in one place without variation in the discharge direction (left and right direction in FIG. 3), and therefore, it becomes easier to take out the sheets from the sheet discharge tray 23.

  Here, when the paper width W1 of the discharged paper P is larger than 1/3 of the width W2 of the paper stacking surface 23a, the side edge portion Pa on the front side of the apparatus of the paper P discharged from the paper discharge port 24 on the center basis. Always overlaps with the side end Pb of the back side of the already loaded paper P, so that the paper P slides smoothly along the already loaded paper and is stacked at the front left corner of the paper discharge tray 23. .

  However, when the discharged paper is, for example, a small-size paper P ′ fed from the manual paper tray 41 (see FIG. 1), the paper is discharged depending on the relationship between the paper width W1 and the width W2 of the paper stacking surface 23a. It is conceivable that the sheet P ′ to be interfered with the sheet already discharged onto the sheet discharge tray 23 and cannot be stacked smoothly.

  For example, when the width W2 of the paper stacking surface 23a is 300 mm or more and the minimum size paper to be discharged is a postcard size (paper width 100 mm), the paper P to be discharged is dropped when the drop prevention stopper 60 is at the position shown in FIG. The sheet P is dropped directly on the sheet stacking surface 23a without overlapping the sheet P stacked along the prevention stopper 60. Therefore, the side edge Pa on the front side of the paper P may hit the side edge Pb on the back side of the paper P already loaded, and the paper may not smoothly slide down to the drop-off prevention stopper 60.

  4 is a side cross-sectional view of the image forming apparatus that discharges the minimum size paper, and FIG. 5 is a plan view of the paper discharge tray (cross section BB ′ in FIG. 4). As shown in FIGS. 4 and 5, by moving the drop-off prevention stopper 60 by a predetermined amount toward the back of the apparatus (the right direction in FIG. 4 and the upward direction in FIG. 5), the side end portion P of the sheet P ′ on the apparatus front side 'A is always superimposed on the side end P'b on the back side of the apparatus of the already loaded paper P' (broken line in the figure), and smoothly slides down along the stacked paper P '. Therefore, even when small-size sheets are continuously discharged, the stacking state in the front-rear direction of the apparatus does not occur.

  The movement range of the drop-off prevention stopper 60 is such that the minimum distance D from the center reference line O of the paper discharged from the paper discharge port 24 to the drop-off prevention stopper 60 is more than 1.5 times the minimum paper width Wmin to be discharged. It is set to be smaller. As a result, the side end portion P′a can always be overlapped with the side end portion P′b even when the minimum size sheets are continuously performed.

  On the other hand, when the drop-off prevention stopper 60 is moved to the vicinity of the discharge position of the small-size paper P ′, the visibility and take-out performance of the stacked paper are deteriorated, and the effect of giving the paper stacking surface 23 a a gradient is obtained. It will disappear. For this reason, it is preferable that the minimum distance D from the center reference line O to the drop-off prevention stopper 60 is set to be larger than the minimum sheet width Wmin to be discharged and smaller than 1.5 times Wmin.

  In addition, when there are three or more types of paper widths to be discharged, the arrangement of the drop-off prevention stopper 60 according to the paper size can be switched by making it possible to lock the drop-off prevention stopper 60 at a position corresponding to each paper width. Smooth and reliable.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the drop-off prevention stopper 60 may be configured to slide along the paper stacking surface 23a, or may be configured to be inserted into an engagement hole provided at a predetermined position on the paper stacking surface 23a. Further, for example, a moving unit that automatically moves the drop-off prevention stopper 60 to a predetermined position in accordance with a paper size input operation by the user may be provided. Here, an upward gradient is also provided in the paper discharge direction of the paper stacking surface 23a. However, a gradient in the paper discharge direction is not necessarily required, and only a downward gradient from the back side of the apparatus toward the front side is required. The image forming apparatus has improved visibility and take-out property.

  The present invention relates to a sheet feeding device, an image forming unit that is disposed above the sheet feeding device and forms an image on a sheet fed from the sheet feeding device, and an original image that is disposed above the image forming unit. An image reading unit to be read, a paper discharge port provided on a side surface of the in-cylinder discharge space provided between the image reading unit and the image forming unit, and a paper discharge disposed on the bottom surface of the in-cylinder discharge space An in-cylinder discharge type image forming apparatus that discharges paper after image formation from a paper discharge port onto a paper discharge tray. The paper discharge tray has a paper stacking surface for receiving the discharged paper. There is a downward slope from the back side to the front side, and a drop-off prevention stopper for preventing the drop-out of the sheet is provided on the front side of the sheet stacking surface so as to be movable back and forth.

  As a result, even if the paper is discharged with reference to the center in the width direction of the paper discharge port, the paper collects on the front side of the paper discharge tray, so that the visibility of the discharged paper from above and from the front is improved and the paper can be easily taken out. Therefore, it is possible to provide an in-body discharge type image forming apparatus that is easy to use even when the image forming apparatus is operated while sitting on a chair or when used by a wheelchair worker. Also, since the drop-off prevention stopper is provided so as to be movable back and forth, the drop-off prevention stopper can be moved to a position where the side edge of the discharged paper does not interfere with the already discharged paper, and the width of the discharged paper Regardless of whether the paper can be stacked stably.

  In addition, since the minimum distance from the center in the width direction of the paper discharged from the paper discharge port to the drop-off prevention stopper is smaller than 1.5 times the minimum paper width to be discharged, the minimum size paper is continuously added. Even when the sheet is discharged, the image forming apparatus does not cause a disturbance in the stacked state. In addition, if the minimum distance from the center in the width direction of the sheet to the stopper for preventing dropping is made larger than the minimum sheet width, the visibility of the sheet and the ease of taking out from the tray can be maintained.

  In addition, since an upward slope is provided in the paper discharge direction on the paper stacking surface, the discharged paper is collected in one place of the paper discharge tray, so that it is easier to take out the paper from the paper discharge tray.

These are front sectional views showing the internal configuration of the image forming apparatus of the present invention. FIG. 3 is a side cross-sectional view showing a state in which a large size sheet is discharged in the image forming apparatus of the present invention. FIG. 5 is a plan view showing a state in which a large-size sheet is discharged to a sheet discharge tray. FIG. 4 is a side cross-sectional view illustrating a state where a minimum size sheet is discharged in the image forming apparatus of the present invention. FIG. 5 is a plan view showing a state in which a minimum-size sheet is discharged to a sheet discharge tray. FIG. 3 is an external perspective view of a conventional image forming apparatus. FIG. 3 is a right side view of a conventional image forming apparatus.

Explanation of symbols

22 In-body discharge space 23 Paper discharge tray 23a Paper stacking surface 24 Paper discharge port 40 Paper feed cassette (paper feed device)
41 Manual paper tray (paper feeder)
60 Stopper stopper 100 Image forming apparatus P (large size) paper P ′ (small size) paper O Center reference line

Claims (4)

A sheet feeding device, an image forming unit disposed above the sheet feeding device and forming an image on a sheet fed from the sheet feeding device, and an image reading unit disposed above the image forming unit and reading a document image A sheet discharge port provided on a side surface of the in-cylinder discharge space provided between the image reading unit and the image forming unit, and a paper discharge tray disposed on the bottom surface of the in-cylinder discharge space An in-cylinder discharge type image forming apparatus that discharges the paper after image formation from the paper discharge port onto the paper discharge tray.
The sheet discharge tray has a sheet stacking surface for receiving discharged sheets having a downward slope from the back side to the front side of the apparatus, and a drop prevention stopper for preventing sheets from dropping on the front side of the sheet stacking surface of the apparatus. An image forming apparatus characterized in that it is provided so as to be movable back and forth. The following conditional expression (1) is satisfied, where D is the minimum distance from the center in the width direction of the sheet discharged from the sheet discharge port to the drop-off prevention stopper, and Wmin is the minimum sheet width to be discharged. The image forming apparatus according to claim 1.
D <1.5 Wmin (1) The following conditional expression (2) is satisfied, where D is the minimum distance from the center in the width direction of the paper discharged from the paper discharge port to the drop-off prevention stopper, and Wmin is the minimum paper width to be discharged. The image forming apparatus according to claim 2.
Wmin <D <1.5Wmin (2) The image forming apparatus according to claim 1, wherein the sheet stacking surface has an upward slope in a sheet discharge direction.

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