Paper feed device and image forming apparatus including paper feed device

According to an embodiment, a paper feed device includes: a tray that has a support surface on which a sheet is placed and is capable of entering a first state and a second state. The first state is a state for placing the sheet on the support surface. The second state is a state for taking out the sheet from the support surface toward a downstream side in a conveying direction and for putting the sheet in an inclined posture heading upward on the downstream side in the conveying direction than an upstream side in the conveying direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2021-103238, filed on Jun. 22, 2021, the entire contents of which are incorporated herein by reference.

FIELD

An embodiment to be described here generally relates to a paper feed device and an image forming apparatus including this paper feed device.

BACKGROUND

In the past, an image forming apparatus includes a cassette for printing an image. A sheet in the cassette is conveyed to an image forming unit in the image forming apparatus and printing is performed by the image forming unit. Since the cassette is usually located in the lower part of the image forming apparatus, the capacity for housing sheets is limited. In this regard, there is known a paper feed device having a large capacity, which is additionally disposed on the side of the image forming apparatus. In this paper feed device, a large amount of sheets are placed on a tray. The paper feed device lifts the tray upward to lift the sheet to a paper feed unit of the image forming apparatus. The paper feed unit feeds the sheets one by one to the image forming unit by a roller.

In the image forming apparatus, the tray is lifted upward while being substantially-horizontal. While the sheet is lifted to the paper feed unit, the orientation in which the sheets are caused to enter a nip formed between the paper feed roller and a separation roller is substantially horizontal. In particular, there is a problem that in the case where the sheet is relatively thick, the sheet is easily jammed. As a countermeasure to this problem, a pickup roller that takes out the sheet from the tray is urged downward to increase the frictional force between the pickup roller and the sheet. In the case where the sheet is relatively thin, the sheets are double-fed, i.e., a plurality of sheets is easily taken out at the same time.

DETAILED DESCRIPTION

According to an embodiment, a paper feed device includes: a tray; a first roller; a second roller; and a third roller. The tray has a support surface on which a sheet is placed and is capable of entering a first state and a second state. The first state is a state for placing the sheet on the support surface. The second state is a state for taking out the sheet from the support surface toward a downstream side in a conveying direction and for putting the sheet in an inclined posture heading upward on the downstream side in the conveying direction than an upstream side in the conveying direction. The first roller takes out the sheet from the tray to the downstream side in the conveying direction. The second roller conveys the sheet taken out by the first roller to the downstream side in the conveying direction. The third roller is provided to face the second roller and forms a nip sandwiching the sheet between the third roller and the second roller. An angle between a reference line and the sheet on the support surface of the tray in the second state is smaller than an angle between the reference line and the sheet on the support surface of the tray in the first state, the reference line connecting a contact position and the nip to each other, the first roller being in contact with the sheet at the contact position.

First Embodiment

A paper feed device according to a first embodiment will be described with reference to the drawings. In the drawings, the same reference symbols denote the same or similar portions. The paper feed device is used in an image processing apparatus1shown inFIG.1. The image processing apparatus1includes, for example, a multifunction device (MFP, Multi-Function Peripherals). The image processing apparatus1includes an operation device10, a scanner device15, a printer device20, a cassette paper feed device25, a controller27, and a paper feed device30according to this embodiment. The image processing apparatus1forms an image on a sheet using a developer such as toner. Examples of the sheet used in the image processing apparatus1include paper, label paper, a resin sheet, a postcard, and an envelope. The type of the sheet (paper type) is not limited as long as the image processing apparatus1is capable of forming an image on the surface of the sheet. For example, the thin sheet described herein means a sheet having a weight of 80 g/m2or less. The thick sheet described herein means a sheet having a weight of 81 g/m2or more.

The image processing apparatus1may perform image processing on the sheet. For example, the image processing apparatus1may perform image processing for applying heat to a sheet on which an image is formed with decolorizing toner to erase the image on the sheet.

In the following, when referring to the relative position, direction, and the like in the image processing apparatus1, words such as front, back, right, left, up, and down centering on the image processing apparatus1are used as long as there is no risk of misunderstanding. The right, left, up, and down respectively represent the right, left, up, and down of a person who stands in front of the image processing apparatus1and looks the rear of the image processing apparatus1. Instead of the front, back, right, left, up, and down, the xyz Cartesian coordinate system shown inFIG.1is used in some cases. The xyz Cartesian coordinate system is a coordinate system fixed to the image processing apparatus1. An x-axis of the xyz Cartesian coordinate system is an axis extending from the back to the front of the image processing apparatus1in the horizontal plane. The x-axis positive direction is a direction from the back to the front of the image processing apparatus1. The x-axis negative direction is a direction opposite to the x-axis positive direction, of directions along the x-axis. A y-axis is an axis extending from the left to the right of the image processing apparatus1in the horizontal plane when viewed from the front to the back of the image processing apparatus1. The y-axis positive direction is a direction from the left to the right of the image processing apparatus1. The y-axis negative direction is a direction opposite to the y-axis positive direction, of directions along the y-axis. The x-axis and the y-axis are perpendicular to each other. A z-axis is an axis extending from the bottom to the top of the image processing apparatus1. The z-axis is perpendicular to the x-axis and the y-axis. The z-axis positive direction is vertically upward. The z-axis negative direction is vertically downward.

The directions along the x-axis, the y-axis, and the z-axis are expressed as the x-axis direction, the y-axis direction, and the z-axis direction. The plane including the x-axis and the y-axis is the xy plane. The plane including the y-axis and the z-axis is the yz plane. The plane including the z-axis and the x-axis is the zx plane. Regarding the shape and posture of the respective members of the image processing apparatus1, the shape and posture fixed to the image processing apparatus1will be described unless otherwise specified.

The operation device10includes a display11and a control panel12. For example, the display11is an image display device such as a liquid crystal display and an organic EL (Electro Luminescence) display. The display11displays various types of information regarding the image processing apparatus1.

The control panel12includes a plurality of buttons. The control panel12accepts an operation of an operator. The control panel12outputs, to the controller27, a signal corresponding to the operation performed by the operator. The display11and the control panel12may be configured as an integrated touch panel.

The scanner device15reads, as light and dark, image information to be read. The scanner device15stores the read image information. The stored image information may be transmitted to another information processing apparatus via a network. The stored image information may be used by the printer device20for forming an image on a sheet.

The printer device20forms an image on a sheet on the basis of the image information generated by the scanner device15or image information received via a communication path. For example, the printer device20includes an image forming device, a fixing device, and a paper ejection device.

The image forming device includes a photoconductor drum, a charging unit, an exposure unit, a development unit, an intermediate transfer unit, a primary transfer roller, and a secondary transfer roller. The charging unit uniformly charges the photoconductor drum. The exposure unit irradiates the photoconductor drum with light to form an electrostatic latent image on the photoconductor drum. The development unit forms a toner image by adhering toner to the electrostatic latent image formed on the photoconductor drum and developing the electrostatic latent image. The toner image on the photoconductor drum is transferred to the intermediate transfer unit by the primary transfer roller. The transferred toner image is caused to move to a secondary transfer position by the intermediate transfer unit. The secondary transfer roller transfers the toner image on the intermediate transfer unit to the sheet that has reached the secondary transfer position.

The number of colors of the toner used for forming an image in the image processing apparatus1is one or more. In the case where toner of a plurality of colors is used, the photoconductor drum, the charging unit, the exposure unit, the development unit, and the primary transfer roller are provided corresponding to the toner of each color.

The fixing device fixes the toner image on the sheet by heating and pressurizing the toner image transferred onto the sheet. As a result, an image is printed on the sheet. The fixing device decolorizes, in the case where, for example, a sheet on which an image has been formed with decolorizing toner is fed, an image of decolorizing toner by heating and pressurizing the image of decolorizing toner. The paper ejection device ejects the sheet to which the toner image has been fixed by the fixing device to the outside of the image processing apparatus1.

The cassette paper feed device25houses, in a cassette, a sheet to be used for image formation or image processing in the printer device20. The cassette paper feed device25conveys the sheet housed in the cassette to the printer device20. The cassette paper feed device25may include a plurality of cassettes.

The outer shape of the paper feed device30is a rectangular parallelepiped shape. The paper feed device30is installed in the lower part of the printer device20and on the right side of the cassette paper feed device25. The paper feed device30houses a plurality of sheets inside. The paper feed device30conveys, on the basis of the operation from the operation device10, a sheet in a conveying direction F and feeds the sheet to the printer device20. In the paper feed device30, the direction in which the sheet is conveyed toward the printer device20is the conveying direction F. At the start of conveying the sheet, the conveying direction F is the y-axis direction. Unless otherwise specified, the conveying direction F is the direction at the time of conveying the sheet.

As shown inFIG.2toFIG.4, andFIG.9, the paper feed device30includes a body31, a first roller33, a second roller34, a third roller35, a first drive device36, a winding device37, a first linear member38, a second linear member39, and an adjustment mechanism40. The body31includes an outer casing45and an inner casing46.

As shown inFIG.2, the outer casing45has a rectangular parallelepiped shape having an opening in the x-axis positive direction. A right frame49disposed parallel to the zx plane is provided near the inner surface the y-axis positive direction inside the outer casing45. A left frame50disposed parallel to the zx plane is provided near the inner surface of the y-axis negative direction inside the outer casing45. Lower ends of the right frame49and the left frame50are connected to each other by a lower frame parallel to the xy plane. Rear ends of the right frame49and the left frame50are connected to each other by a rear frame parallel to the yz plane.

The inner casing46includes a front cover53, a bottom plate54, a first support portion55, a second support portion56, a third support portion (second support member)57, a first guide member59, a second guide member60, and a tray61. The front cover53covers the opening of the outer casing45so as to be openable/closable. A handle65on which a hand is to be put when causing the front cover53to move in the x-axis direction is provided on the surface of the front cover53in the x-axis positive direction.

The bottom plate54is a plate member that is connected to the lower end of the front cover53and is capable of moving together with the front cover53. The bottom plate54has a plate shape parallel to the xy plane. The first support portion55has a length in the z-axis positive direction from the end of the bottom plate54in the y-axis negative direction. The second support portion56has a length in the z-axis positive direction from the end of the bottom plate54in the x-axis negative direction. The second support portion56is connected to the end of the first support portion55in the x-axis negative direction. The third support portion57has a length in the z-axis positive direction from the end of the bottom plate54in the y-axis positive direction. The third support portion57is connected to the end of the second support portion56in the y-axis positive direction. The first, second, and third support portions55,56, and57have a U-shape that opens in the x-axis positive direction when viewed along the z-axis. The first, second, and third support portions55,56, and57are each formed of a steel plate or the like.

The first guide member59has a length in the z-axis positive direction from the end on the inner side than the end of the bottom plate54in the x-axis positive direction. The second guide member60has a length in the z-axis positive direction from the end on the inner side than the end of the bottom plate54in the x-axis negative direction and on the inner side than the second support portion56.

The tray61has a flat plate shape. A support surface66that is an upper surface of the tray61is flat. The support surface66is formed of one member, i.e., the tray61. A first through hole67and a second through hole68are formed in the tray61. The tray61is disposed in the area that is on the bottom plate54and surrounded by the first, second, and third support portions55,56, and57. The first through hole67is located at the end of the tray61in the x-axis positive direction. The first guide member59is provided in the first through hole67. The second through hole68is located at the end of the tray61in the x-axis negative direction. The second guide member60is provided in the second through hole68. As described below, the tray61is capable of entering a first state CH (seeFIG.5) and a second state CG (seeFIG.6).

The first state CH shown inFIG.5is a state for placing a sheet S on the support surface66of the tray61from the outside of the paper feed device30. In the tray61in the first state CH, the support surface66is along the horizontal plane. The sheet S is placed on the support surface66. Meanwhile, the second state CG shown inFIG.6is a state for taking out the sheet S from the support surface66toward a downstream side FA in the conveying direction F in which the sheet S is conveyed. Hereinafter, the side opposite to the downstream side FA in the conveying direction F will be referred to as the upstream side FB. However, the downstream side FA and the upstream side FB in the drawings conventionally indicate the orientations of the downstream side FA and the upstream side FB and are originally orientations with respect to the reference. The same applies also to the first side GA and the second side GB described below. The tray61in the second state CG puts the sheet S in an inclined posture heading upward on the downstream side FA than the upstream side FB. In other words, in the tray61in the second state CG, the support surface66is gradually inclined heading upward toward the downstream side FA. In the tray61, the sheet S is placed on the support surface66.

As shown inFIG.2, the third support portion57is disposed on the upstream side FB than the sheet S placed on the support surface66. The third support portion57supports the sheet S. As shown inFIG.2andFIG.7, a low-friction member69is provided on the outer surface of the third support portion57facing the downstream side FA. For example, the low-friction member69is formed of PTFE (polytetrafluoroethylene resin). The dynamic frictional force between the low-friction member69and the sheet S is smaller than the dynamic frictional force between the third support portion57and the sheet S. In this embodiment, the low-friction member69has a length in the up-and-down direction and includes a plurality of low-friction members69in the third support portion57. The plurality of low-friction members69is spaced apart from each other in the x-axis direction.

As shown inFIG.3andFIG.6, the first, second, and third rollers33,34, and35each have a cylindrical shape. The first roller33is supported by an arm70so as to be rotatable about a rotation shaft CA of the first roller33. For example, the first roller33is positioned such that the rotation shaft CA is along the horizontal plane. Note thatFIG.6a cross-sectional view taken along the plane perpendicular to the rotation shaft CA of the first roller33. The first roller33takes out the sheet S from the tray61toward the downstream side FA. Hereinafter, the position where the first roller33is in contact with the sheet S will be referred to as the contact position PA. The second roller34is located on the downstream side FA than the first roller33. For example, the second roller34is positioned such that a rotation shaft CB of the second roller34is along the horizontal plane. The second roller34conveys the sheet S taken out by the first roller33to the downstream side FA. The second roller34is in contact with the first surface of the sheet S.

The third roller35is located below the second roller34so as to face the second roller34. For example, the third roller35is positioned such that a rotation shaft CC of the third roller35is along the horizontal plane. The third roller35forms a nip NA sandwiching the sheet S between the third roller35and the second roller34. The nip NA is disposed on the downstream side FA than the contact position PA and above the contact position PA. The third roller35is in contact with the second surface that is the back side of the first surface of the sheet S.

Now, the line connecting the contact position PA and the nip NA to each other is defines as the reference line LA (seeFIG.6). The angle between the reference line LA and the sheet S on the support surface66of the tray61in the second state CG (seeFIG.6) is an angle BA. The angle BA is an angle that is on the downstream side FA than the contact position PA and below the reference line LA. The angle between the reference line LA and the sheet S on the support surface66of the tray61in the first state CH (seeFIG.5) is an angle BB. The angle BA is smaller than the angle BB. The second roller34and the third roller35are rotatably supported by a support member32(seeFIG.6). For example, the support member32is formed of metal. The upper end of the support member32is gradually inclined on the downstream side FA toward upward. The upper end of the support member32is directed toward the nip NA.

The first drive device36supplies a drive force for raising and lowering the tray61in the up-and-down direction. As shown inFIG.4, the first drive device36includes a body and a drive shaft72. By applying a voltage in a predetermined orientation to the body71, the body71causes the drive shaft72to rotate about the axis of the drive shaft72. For example, the body71of the first drive device36is fixed to the bottom plate54via a fixture73. The first drive device36is connected to the controller27and is controlled by the controller27.

In this embodiment, as shown inFIG.4, the paper feed device30includes, as the winding device37, a first winding unit76and a second winding unit77. The first winding unit76and the second winding unit77are pulleys having the same shape. The central portion in the width direction of each of the first winding unit76and the second winding unit77is recessed toward the inside in the radial direction. The first winding unit76and the second winding unit77are fixed to the drive shaft72of the first drive device36coaxially with the drive shaft72. The winding device37may include only one pulley.

For example, the first linear member38and the second linear member39are each a metal wire. The first linear member38and the second linear member39may be formed of nylon or the like. In this embodiment, the paper feed device30includes the first linear member38. As shown inFIG.4andFIG.5, one ends of the first linear members38are wound around the first winding unit76and the second winding unit77. As shown inFIG.5, the first linear members38are fed from the first winding unit76and the second winding unit77and routed by a tensioner80and a first intermediate pulley81. The first linear member38wound around the first intermediate pulley81has a length downward from the first intermediate pulley81. As shown inFIG.8, a stopper82is fixed to the second support portion56or the like so as to cover the recess of the first intermediate pulley81from above. The stopper82prevents, when the first linear member38is loosened, the first linear member38from coming off from the first intermediate pulley81. As shown inFIG.9, a large-diameter portion84is provided at the other end (first end) opposite to one end of the first linear member38. That is, the first linear member38includes the large-diameter portion84. The large-diameter portion84has an outer diameter larger than those in the other portions of the first linear member38.

As shown inFIG.4, the paper feed device30includes a pair of second linear members39. One ends of the second linear members39are wound around the first winding unit76and the second winding unit77. As shown inFIG.5, the second linear members39are fed from the first winding unit76and the second winding unit77and routed by the tensioner80and a second intermediate pulley87. The second linear member39wound around the second intermediate pulley87has a length downward from the second intermediate pulley87. As shown inFIG.9, a support portion89is provided at the other end (second end) opposite to one end of the second linear member39. That is, the second linear member39includes the support portion89. The support portion89has an outer diameter larger than those in the other portions of the second linear member39.

The large-diameter portions84of the pair of first linear members38are connected to a first portion201of the tray61. For example, the first portion201is the end of the tray61on the downstream side FA. The large-diameter portions84of the pair of first linear members38are connected to the first portion201of the tray61so as to be spaced apart from each other in a first direction G that is along the horizontal plane and perpendicular to the conveying direction F. The first direction G is a direction along the support surface66of the tray61. The first direction G may be the conveying direction F. The support portions89of the pair of second linear members39are located below the end of the tray61on the upstream side FB.

As shown inFIG.9, the adjustment mechanism40supports a second portion202of the tray61from below the second portion202. The second portion202is the end of the tray61on the upstream side FB. The second portion202is located on the upstream side FB than the first portion201in the tray61. As shown inFIG.10, the adjustment mechanism40includes a pair of adjustment members93and94, a pinion gear95, and a second drive device96. As shown inFIG.10toFIG.12, the adjustment member93includes a narrow portion99, a wide portion100, an inclined portion101, and a high-thick portion102. The narrow portion99, the wide portion100, the inclined portion101, and the high-thick portion102are located in this order from the central portion of the tray61in the first direction G toward the first side GA in the first direction G. Hereinafter, the first side GA in the first direction G will be referred to simply as the first side GA. The side opposite to the first side GA in the first direction G will be referred to as the second side GB. The narrow portion99has a rectangular parallelepiped shape having a length in the first direction G. a first rack gear105and a second rack gear106are respectively formed on the outer surfaces facing the upstream side FB and the downstream side FA in the narrow portion99.

The wide portion100projects to the upstream side FB than the narrow portion99. The inclined portion101gradually projects downward toward the first side GA. The surface facing downward of the inclined portion101is a locking surface109. The locking surface109is gradually inclined downward toward the first side GA. The thickness of the high-thick portion102(length in the up-and-down direction) is similar to that of the thickest portion in the inclined portion101. A slit110penetrating the high-thick portion102, the inclined portion101, and the wide portion100in the up-and-down direction is formed at the end on the first side GA of the high-thick portion102, the inclined portion101, and the wide portion100. The slit110opens on the outer surface facing the first side GA of the high-thick portion102. The width of the slit110(length in the conveying direction F) is larger than the diameter of the second linear member39and smaller than the diameter of the support portion89.

A recessed and projecting fitting having a length along the first direction G is formed on the lower surface of the tray61and the upper surface of the adjustment member93. The adjustment member93is provided on the lower surface of the tray61so as to be movable along the first direction G. The second linear member39is disposed in the slit110. The support portion89of the second linear member39is locked to the locking surface109from below the locking surface109. The support portion89supports the tray61via the adjustment member93. The support portion89abuts on the second portion202of the tray61via the adjustment member93. In order to connect the support portion89of the second linear member39to the adjustment member93, the second linear member39is inserted through the slit110of the adjustment member93. The support portion89of the second linear member39is locked to the locking surface109.

The adjustment member94is configured in the same manner as the adjustment member93except for the second rack gear106. As shown inFIG.10, the adjustment member94includes a narrow portion114, a wide portion115, an inclined portion116, and a high-thick portion117respectively configured in the same manner as the narrow portion99, the wide portion100, the inclined portion101, and the high-thick portion102of the adjustment member93.

A first rack gear120is formed on the outer surface facing the downstream side FA of the narrow portion114. The wide portion115projects to the downstream side FA than the narrow portion114. The inclined portion116gradually projects downward toward the second side GB. The surface facing downward of the inclined portion116is a locking surface124. The locking surface124is gradually inclined downward toward the second side GB. A slit125penetrating the high-thick portion117, the inclined portion116, and the wide portion115in the up-and-down direction is formed at the end on the second side GB of the high-thick portion117, the inclined portion116, and the wide portion115.

The adjustment member94is provided on the lower surface of the tray61so as to be movable along the first direction G. The second linear member39is disposed in the slit125. The support portion89of the second linear member39is locked to the locking surface124from below the locking surface124.

The pinion gear95engages with the first rack gear105of the adjustment member93and the first rack gear120of the adjustment member94. The second drive device96includes a drive motor127and a worm gear128. In the drive motor127, the body causes a drive shaft to rotate. For example, the body of the drive motor127is fixed to the tray61. The worm gear128is fixed to the drive shaft. The worm gear128engages with the second rack gear106of the adjustment member93. The second drive device96is connected to the controller27and is controlled by the controller27.

The adjustment mechanism40configured as described above operates as follows. For example, the worm gear128shown inFIG.10rotates in a predetermined direction, and the adjustment member93that engages with the worm gear128moves to the first side GA. The adjustment member94that engages with the adjustment member93via the pinion gear95moves to the second side GB. The locking surfaces109and124move so as to be separated from each other. The state of the locking surfaces109and124at this time is referred to as the surface separation state. Meanwhile, the worm gear128rotates in the orientation opposite to the predetermined orientation, and the adjustment member93that engages with the worm gear128moves to the second side GB. The adjustment member94that engages with the adjustment member93via the pinion gear95moves to the first side GA. The state of the locking surfaces109and124at this time is referred to as the surface approaching state. As described above, the second drive device96causes the pair of adjustment members93and94to move along the first direction G.

As shown inFIG.9, when the tray61is in the first state CH, the locking surfaces109and124are in the surface approaching state. As shown inFIG.11, the support portion89of the second linear member39is in contact with the corresponding lower end of the respective locking surfaces109and124of the pair of adjustment members93and94. The distance in the up-and-down direction between the support portion89of the second linear member39and the tray61is relatively long, and the support portion89of the second linear member39is separated from the tray61. At this time, the support surface66of the tray61is along the horizontal plane. As shown inFIG.6, when the tray61is in the second state CG, the locking surfaces109and124are in the surface separation state. As shown by the two-dot chain line inFIG.11, the support portion89of the second linear member39is in contact with the corresponding upper end of the respective locking surfaces109and124of the pair of adjustment members93and94. The distance in the up-and-down direction between the support portion89of the second linear member39and the tray61is relatively short, and the support portion89of the second linear member39approaches the tray61. In the tray61, the support surface66is gradually inclined upward toward the downstream side FA.

As described above, in the paper feed device30, when changing the state of the tray61from one of the first state CH and the second state CG to the other, the distance in the up-and-down direction between the support portion89of the second linear member39and the second portion202of the tray61is changed. As shown inFIG.5, in the paper feed device30, when the tray61is positioned at the lowermost position of the movable range of the tray61, the tray61is in the first state CH. The locking surfaces109and124of the adjustment mechanism40are in the surface approaching state. While the tray61is caused to move upward by the first drive device36, the state of the tray61is switched from the first state CH to the second state CG. At this time, the locking surfaces109and124of the adjustment mechanism40is in the surface separation state.

The controller27includes a CPU (Central Processing Unit) and a memory. The CPU executes the control program stored in the memory. The controller27controls the first drive device36, the second drive device96, and the like.

Next, the operation of the image processing apparatus1configured as described above will be described with an emphasis on the operation of the paper feed device30. An operator pulls the inner casing46in the x-axis positive direction from the outer casing45of the paper feed device30. As shown inFIG.5, in the inner casing46, thick paper SA that is a relatively thick sheet S, is placed on the support surface66of the tray61. Since the support surface66is formed of one member, i.e., the tray61, to be flat, it is possible to prevent the sheet S such as the thick paper SA from being broken or having a bending tendency. The operator pushes the inner casing46into the outer casing45. The controller27causes the tray61to move upward by the first drive device36. Specifically, the controller27increases the lengths of the first and second linear members38and39wound around the first and second winding units76and77by the first drive device36.

While the tray61is caused move upward, as shown inFIG.13, the controller27switches the state of the tray61from the first state CH to the second state CG by the second drive device96. Specifically, the controller27changes the state of the locking surfaces109and124from the surface approaching state to the surface separation state. The end of the tray61on the upstream side FB is lowered and the tray61enters the second state CG. Since the support surface66is inclined, the thick paper SA easily comes into contact with the low-friction member69of the third support portion57. Since the dynamic frictional force between the low-friction member69and the thick paper SA is smaller than the dynamic frictional force between the third support portion57and the thick paper SA, the thick paper SA easily moves upward with respect to the low-friction member69. As shown inFIG.6, the thick paper SA on the support surface66of the tray61comes into contact with the first roller33from below the first roller33. For example, the fact that the thick paper SA has come into contact with the first roller33can be detected by a sensor that detects the position of the arm70.

A paper feed device135according to a Comparative Example will be described with reference toFIG.14. In the paper feed device135, when the sheet S is taken out to the downstream side from the support surface66, the tray61is in the first state CH. For example, in the case where the sheet S is thin paper SB that is relatively thin, the thin paper SB on the support surface66is conveyed to the downstream side FA along the support surface66. The thin paper SB abuts on the support member32. Since the thin paper SB has a relatively weak elasticity, the end of the thin paper SB on the downstream side FA deforms along the support member32. The thin paper SB is guided to the nip NA while being curved to project downward as shown in a line LB of a two-dot chain line.

For example, in the case where the sheet S is the thick paper SA, the elasticity of the thick paper SA is relatively strong. Since the thick paper SA is hard to bend even if the thick paper SA abuts on the support member32, the first roller33is easy to slip with respect to the thick paper SA. As a countermeasure, it is conceivable to urge the first roller33downward by an urging member such as a spring. When the first roller33is urged, the first roller33is hard to slip with respect to the thick paper SA. When the thin paper SB is used as the sheet S in this state, the thin paper SB is easily double-fed to the downstream side FA.

In the paper feed device30according to this embodiment shown inFIG.6, when the sheet S is taken out from the support surface66to the downstream side FA, the sheet S is in the second state CG. For this reason, regardless of whether the sheet S is the thick paper SA or the thin paper SB, the sheet S is hard to abut on the support member32and the sheet S is reliably fed to the nip NA.

An image is formed by the printer device20on the thick paper SA guided to the nip NA. The thick paper SA is ejected by a paper ejection device.

As described above, in the paper feed device30according to this embodiment, the tray61is capable of entering the first state CH (seeFIG.5) and the second state CG (seeFIG.6). It is possible to easily place the sheet S on the support surface66of the tray61in the first state CH from the outside of the paper feed device30. The angle BA between the reference line LA and the sheet S on the support surface66of the tray61in the second state CG is smaller than the angle BB between the reference line LA and the sheet S on the support surface66of the tray61in the first state CH (seeFIG.6). When the tray61enters the second state CG and the sheet S is taken out from the support surface66to the downstream side FA, the support surface66is further along the reference line LA. By providing no urging member to the first roller33, it is possible to easily feed the thick paper SA to the nip NA and prevent the thin paper SB from being double-fed.

The paper feed device30includes the winding device37, the first linear member38, and the second linear member39. The winding device37winds or feeds out the first and second linear members38and39to adjust the lengths of the first and second linear members38and39. By adjusting the lengths of the first and second linear members38and39, it is possible to cause the tray61to move in the up-and-down direction. By changing the distance between the support portion89of the second linear member39and the tray61, it is possible to change the state of the tray61from one of the first state CH and the second state CG to the other. The paper feed device30includes the first drive device36and the adjustment mechanism40. By adjusting, by the first drive device36, the lengths of the first linear member38and the second linear member39fed out from the winding device37, it is possible to cause the tray61to automatically move in the up-and-down direction.

As shown inFIG.10andFIG.11, the adjustment mechanism40includes the adjustment member93and the second drive device96. When the second drive device96causes the adjustment member93to move along the first direction G, the position in the up-and-down direction of the portion of the locking surface109with which the support portion89comes into contact changes. The second portion202of the tray61supported by the adjustment member93moves in the up-and-down direction with respect to the support portion89. With a simple configuration of the adjustment member93and the second drive device96, it is possible to change the distance between the support portion89of the second linear member39and the tray61in a continuous manner and configure the tray61to be capable of entering the first state CH and the second state CG. It is possible to change the inclination of the tray61in a continuous manner between the first state CH and the second state CG. The paper feed device30includes the third support portion57and the low-friction member69. When the sheet S comes into contact with the low-friction member69, e.g., when the sheet S enters the second state CG, the sheet S easily moves upward with respect to the low-friction member69.

Note that the adjustment mechanism40does not necessarily need to include the adjustment member94and the pinion gear95. In this case, the paper feed device30includes one first linear member38and one second linear member39. The tray61moves in the up-and-down direction by transmitting the drive force of the first drive device36to the first linear member38and the second linear member39. The paper feed device may include a gear instead of the first and second linear members38and39. In this case, the tray61may move in the up-and-down direction by transmitting the drive force of the first drive device36to the gear.

Second Embodiment

Next, a second embodiment of the present invention will be described with reference toFIG.15toFIG.17. The same parts as those in the embodiment described above will be denoted by the same reference symbols, description thereof will be omitted, and only differences will be described. As shown inFIG.15toFIG.17, a paper feed device140according to this embodiment includes an adjustment mechanism141instead of the adjustment mechanism40of the paper feed device30according to the first embodiment. The paper feed device140is used in an image processing apparatus3. The tray61shown inFIG.15toFIG.17is located at the lowermost position of the movable range of the tray61and is in the first state CH. The adjustment mechanism141includes a pair of spring members142and143and first support members144and145. Note that inFIG.15, the first support members144and145are shown by a two-dot chain line. The spring members142and143support the end of the tray61on the upstream side FB from below the end. The spring members142and143are provided on the lower surface of the tray61. In this embodiment, the spring members142and143are torsion coil springs.

The spring member142has a U-shape in which the outside in the first direction G (the first side GA in this example) opens when viewed from the conveying direction F. As shown inFIG.16andFIG.17, the spring member142includes a first arm portion148, a second arm portion149, and a connection member150. The first arm portion148and the second arm portion149each have a flat plate shape and the respective thickness directions are along the up-and-down direction. The second arm portion149is located at a position separated downward from the first arm portion148. The first arm portion148includes a slit153penetrating the first arm portion148in the up-and-down direction. The slit153opens to the first side GA. The width of the slit153(length in the conveying direction F) is larger than the diameter of the second linear member39and smaller than the diameter of the support portion89. The second arm portion149includes a slit154penetrating the second arm portion149in the up-and-down direction. The slit154opens to the first side GA. The width of the slit154is larger than the diameter of the second linear member39and smaller than the diameter of the support portion89.

The connection member150connects the end of the first arm portion148on the second side GB and the end of the second arm portion149on the second side GB to each other. The first arm portion148, the second arm portion149, and the connection member150configuring the spring member142are integrally formed by, for example, bending a steel plate.

The first arm portion148is fixed to the end of the tray61on the first side GA from below the end. The support portion89of the second linear member39abuts on the second arm portion149from below the second arm portion149. The second linear member39is provided in each of the slit153of the first arm portion148and the slit154of the second arm portion149.

As shown inFIG.15, the spring member143is configured in the same manner as the spring member142. The spring member143has a U shape in which the outside of the first direction G (the second side GB in this example) opens when viewed from the conveying direction F. The first arm portion of the spring member143is fixed to the end of the tray61on the second side GB from below the end. The support portion89of the second linear member39abuts on the second arm portion of the spring member142from below the second arm portion.

For example, the first support members144and145each have a flat plate shape. The first support members144and145are provided in the inner casing46of the body31. The first support members144and145support the second portion202of the tray61in the first state CH from below the second portion202. The first support member144supports the end of the tray61on the first side GA. The first support member145supports the end of the tray61on the second side GB. The first support members144and145support the second portion202of the tray61from below to cause the tray61to enter the first state CH.

Next, the operation of the paper feed device140configured as described above will be described. An operator places the thick paper SA on the support surface66of the tray61. Since the second portion202of the tray61in the first state CH is supported by the first support members144and145, the load due to the placing of the thick paper SA does not act on the spring members142and143. The controller27causes the tray61to move upward by the first drive device36. When the tray61is separated from the first support members144and145, the load or the like acting on the tray61and the thick paper SA acts on the spring members142and143. For example, the spring member142deforms such that the second arm portion149to which the support portion89is locked approaches the first arm portion148as shown by a two-dot chain line inFIG.16. The second portion202of the tray61is lowered and the tray61enters the second state CG.

As described above, in the paper feed device140according to this embodiment, it is possible to easily feed out the sheet S to the nip NA when the sheet S is thick while suppressing the double-feeding when the sheet S is thin. The adjustment mechanism141includes the spring members142and143and the first support members144and145. With a simple configuration of the spring members142and143and the first support members144and145, it is possible to configure the tray61to be capable of entering the first state CH and the second state CG.

The adjustment mechanism141does not necessarily need to include the spring members142and143. In this case, when the tray61is in the first state CH and is supported by the first support members144and145, the portion of the second linear member39below the tray61is in a loosened state. The spring members142and143may be compression coil springs or the like. The adjustment mechanism141does not necessarily need to include the spring member143and the first support member145.

As shown inFIG.18, a paper feed device160may include an annular member161and a third support member162instead of the low-friction member69of the paper feed device30according to the first embodiment. In this modification, a through hole165is provided in the intermediate portion in the up-and-down direction of the third support portion57. For example, the annular member161is an endless belt. The annular member161has a length in the up-and-down direction. The central portion in the conveying direction F of the annular member161is in the through hole165. The portion (part) of the annular member161on the downstream side FA is on the downstream side FA than the third support portion57. The portion of the annular member161on the upstream side FB is located on the upstream side FB than the third support portion57. The entire annular member161may be located on the downstream side FA than the third support portion57.

The third support member162has a round bar shape having a length in the first direction G. The paper feed device160includes a plurality of third support members162. The plurality of third support members162is disposed so as to be spaced apart from each other in the up-and-down direction. The plurality of third support members162is located in the through hole165. Both ends of the plurality of third support members162are attached to the peripheral edge of the through hole165in the third support portion57. The plurality of third support members162is disposed in the annular member161and supports the annular member161.

When the tray61enters the second state CG, the thick paper SA easily comes into contact with the annular member161. The portion of the annular member161on the downstream side FA moves upward together with the thick paper SA. In this modification, the thick paper SA easily moves upward with respect to the third support portion57.

In accordance with at least one of the embodiments described above, since the tray61is capable of entering the first state CH and the second state CG and the angle BA is smaller than the angle BB, it is possible to easily feed out the sheet S to the nip NA when the sheet S is thick while suppressing the double-feeding when the sheet S is thin.