Sheet feed cassette and image forming apparatus

Abstract

To provide a paper feeding cassette capable of suppressing failure.SOLUTION: A paper feeding cassette 51 includes a push-up plate 55 which is attached to an image forming apparatus, arranged on an inner bottom surface 53, and on which recording media are placed, a lift-up mechanism M1 for pushing up the push-up plate 55, a fixing part 90 for fixing the push-up plate 55 to the inner bottom surface 53, and a release part 80 for releasing the fixing of the push-up plate 55 by the fixing part 90 in conjunction with the lift-up mechanism M1.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a paper feed cassette and an image forming apparatus, and more particularly to a paper feed cassette that accommodates recording media and an image forming apparatus that includes the paper feed cassette. [Background technology]

[0002] In recent years, image forming apparatuses, such as multifunction peripherals, have been equipped with a paper feed cassette capable of storing multiple recording media for forming images on sheet-like recording media such as paper. This paper feed cassette is equipped with a lift-up mechanism that lifts the multiple recording media upward, regardless of the number of recording media stored, in order to transport the recording media starting from the top recording medium. When no recording media are stored in the lift-up mechanism, a portion of the lift-up mechanism is free to move upward. For this reason, for example, during transportation of the image forming apparatus prior to installation, external vibrations can cause a portion of the lift-up mechanism to move up and down, resulting in a malfunction.

[0003] Japanese Patent Application Laid-Open No. 6-64764 describes an image forming apparatus having a paper feed cassette with a configuration that sets a bottom plate and side fences that regulate the position of both ends of the width of the paper in a predetermined position when the paper feed cassette is installed in the device body, and the paper feed cassette is characterized in that the side fences are arranged to be slidable in the width direction of the paper, and have a structure that engages with the side of the bottom plate to hold the bottom plate when slid to a position corresponding to the predetermined position.

[0004] In the image forming apparatus described in JP-A-6-64764, the bottom plate is held in place when the side fences are slid to a position corresponding to a predetermined position, preventing the bottom plate from vibrating during transport. However, if the bottom plate is raised while the side fences are holding it, a load is placed on the drive source, which can cause a malfunction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-64764 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and one of the objects of the present invention is to provide a paper feed cassette that is less likely to malfunction.

[0007] Another object of the present invention is to provide an image forming apparatus that suppresses malfunctions. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, according to one aspect of the present invention, the paper feed cassette is a paper feed cassette that is attached to an image forming device and includes a boost plate that is arranged on the inner bottom surface and on which a recording medium is placed, a lift-up mechanism that pushes up the boost plate, a fixing portion that fixes the boost plate to the inner bottom surface, and a release portion that works in conjunction with the lift-up mechanism to release the fixation of the boost plate by the fixing portion.

[0009] According to another aspect of the present invention, an image forming apparatus includes the above-described paper feed cassette. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of an MFP according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating an example of the internal configuration of an MFP. [Figure 3] FIG. 2 is a perspective view illustrating an example of a paper feed cassette. [Figure 4] FIG. 2 is a plan view illustrating an example of a paper feed cassette. [Figure 5] FIG. 2 is a perspective view showing an example of a drive unit. [Figure 6] FIG. 10 is a perspective view showing an example of a connection between a lift-up mechanism and a drive unit. [Figure 7] FIG. 10 is a first plan view schematically showing an example of a boost plate in a standby position and its surroundings. [Figure 8] FIG. 10 is a first side view schematically showing an example of a boost plate in a standby position and its surroundings. [Figure 9] FIG. 10 is a second plan view schematically illustrating an example of the boost plate and its surroundings in the standby position. [Figure 10] FIG. 10 is a second side view schematically showing an example of the lifting plate and its surroundings in the standby position. [Figure 11] FIG. 10 is a plan view schematically illustrating an example of a push-up plate in a push-up position and its surroundings. [Figure 12] FIG. 10 is a side view schematically illustrating an example of a push-up plate in a push-up position and its surroundings. [Figure 13] FIG. 10 is a first plan view schematically showing an example of a boost plate and its periphery in a modified example. [Figure 14] FIG. 10 is a second plan view schematically showing an example of a boost plate and its periphery in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are designated by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0012] In the following description, an MFP (Multi Function Peripheral) will be used as an example of an image forming apparatus. The MFP has the function of forming an image on a recording medium. Recording media include paper and OHP (Over Head Projector) film. Here, the case where paper is used as the recording medium will be described as an example.

[0013] FIG. 1 is a perspective view of an MFP according to one embodiment of the present invention. Here, the X, Y, and Z directions are defined, each perpendicular to the other. The X and Y directions are parallel to a horizontal plane. The direction parallel to the Y direction is called the front-to-rear direction, the direction from the back of the MFP1 toward the front (the direction from the positive side to the negative side in the Y direction) is called the front direction, and the horizontal direction from the front to the back (the direction from the negative side to the positive side in the Y direction) is called the rear direction. The direction parallel to the X direction is called the left-to-right direction, the direction from the right side toward the left side of the MFP1 (the direction from the positive side to the negative side in the X direction) is called the left direction, and the horizontal direction from the left side toward the right side (the direction from the negative side to the positive side in the X direction) is called the right direction.

[0014] Referring to FIG. 1, MFP 1 includes automatic document feeder 11, document reading unit 13, image forming unit 15, and paper feeding unit 17.

[0015] The automatic document feeder 11 automatically transports multiple documents set on a document tray one by one to a document reading position of the document reading unit 13, and ejects the documents onto a document output tray after the images formed on them have been read by the document reading unit 13. The document reading unit 13 includes a light source that irradiates light onto the documents transported to the document reading position and a photoelectric conversion element that receives light reflected from the documents, and scans the document image according to the size of the documents. The photoelectric conversion element converts the received light into image data, which is an electrical signal. The document reading unit 13 reads the documents and outputs the image data it acquires. The document reading unit 13 stores the image data in a storage device such as a hard disk drive (HD), for example.

[0016] The paper feed unit 17 includes a paper feed cassette 51 that stores paper sheets, which are recording media. The paper feed cassette 51 can store multiple sheets of paper. The paper feed cassette 51 can be pulled out forward (from the positive side to the negative side in the Y direction) from the housing 1A of the MFP 1 so that the user can supply paper sheets. The state in which the paper feed cassette 51 is pulled out is the open state, and the state in which the paper feed cassette 51 is not pulled out from the housing 1A is the closed state. FIG. 1 shows the paper feed cassette 51 pulled out in the open state. The paper feed cassette 51 is a cube with an open top, and in the open state, the user can supply a stack of paper sheets consisting of multiple sheets of paper from the top. The paper feed unit 17 transports the multiple sheets of paper stored in the paper feed cassette 51 one by one to the image forming unit 15.

[0017] The image forming unit 15 forms images using a well-known electrophotographic method, and forms an image on paper transported by the paper feed unit 17 based on image data, and discharges the paper with the image formed on it to a paper output tray.

[0018] FIG. 2 is a cross-sectional view schematically illustrating an example of the internal configuration of an MFP. Referring to FIG. 2, image forming section 15 has developing units 20Y, 20M, 20C, and 20K, and toner bottles 21Y, 21M, 21C, and 21K. Here, "Y," "M," "C," and "K" represent yellow, magenta, cyan, and black, respectively. Developing units 20Y, 20M, 20C, and 20K correspond to yellow, magenta, cyan, and black, respectively. Toner bottles 21Y, 21M, 21C, and 21K correspond to yellow, magenta, cyan, and black, respectively.

[0019] The developing units 20Y, 20M, 20C, and 20K and the toner bottles 21Y, 21M, 21C, and 21K differ only in the color of the toner they handle, so here, the developing unit 20Y and the toner bottle 21Y for forming a yellow image will be described.

[0020] The toner bottle 21Y contains yellow toner. The toner bottle 21Y rotates using a toner bottle motor as a drive source and discharges toner to the outside. The toner discharged from the toner bottle 21Y is supplied to the developing unit 20Y. The toner bottle 21Y supplies developer to the developing unit 20Y when the remaining amount of toner contained in the developing unit 20Y falls below a predetermined lower limit.

[0021] The transfer belt 30 is suspended without slack by a drive roller 31 and a driven roller 32. When the drive roller 31 rotates counterclockwise in FIG. 2, the transfer belt 30 rotates counterclockwise in the drawing at a predetermined speed. As the transfer belt 30 rotates, the driven roller 32 rotates counterclockwise.

[0022] The developing unit 20Y contains developer. The developer contains non-magnetic toner and magnetic carrier. The developing unit 20Y receives toner from a toner bottle 21Y and agitates the toner and carrier. The developing unit 20Y forms a toner image using the toner contained in the developer and transfers the toner image to the transfer belt 30. The timing at which the developing unit 20Y transfers the toner image onto the transfer belt 30 is adjusted by detecting a reference mark on the transfer belt 30.

[0023] When forming a full-color image, the MFP 1 drives all of the developing units 20Y, 20M, 20C, and 20K. As a result, yellow, magenta, cyan, and black toner images are superimposed on the transfer belt 30. When forming a monochrome image, the MFP 1 drives any one of the developing units 20Y, 20M, 20C, and 20K. It is also possible to form an image using a combination of two or more of the developing units 20Y, 20M, 20C, and 20K.

[0024] In the MFP 1 of this embodiment, multiple types of rollers are arranged on the paper transport path. Each of the multiple types of rollers is basically cylindrical and rotates around a central axis of rotation, bringing the side surface into contact with the paper.

[0025] The MFP 1 includes a pickup roller 41, a paper feed roller 42, a separation roller 43, a transport roller 33, a timing roller 34, a transfer roller 35, a fuser roller 36, and a discharge roller 37. The pickup roller 41, the paper feed roller 42, the transport roller 33, the timing roller 34, the fuser roller 36, and the discharge roller 37 are rotated by a torque transmitted from a drive source such as a motor, and transport paper using friction generated at the portions that come into contact with the paper. Furthermore, the separation roller 43 and the transfer roller 35 do not receive a torque transmitted from the drive source.

[0026] A plurality of sheets of paper are set in paper feed cassette 51. The plurality of sheets of paper stored in paper feed cassette 51 are picked up in order from the top by pickup roller 41 provided corresponding to paper feed cassette 51. The paper picked up by pickup roller 41 is transported by paper feed roller 42 and enters a transport path. The paper transported by paper feed roller 42 to transport roller 33 is further transported by transport roller 33 through the transport path to reach timing roller 34.

[0027] Timing rollers 34 transport the paper conveyed by transport rollers 33 at a predetermined timing. The paper conveyed along the transport path by timing rollers 34 enters a nip formed between transfer belt 30 and transfer roller 35. The timing at which timing rollers 34 start transporting the paper is determined based on the timing at which the toner image formed on transfer belt 30 reaches the nip. This causes the toner image to be transferred to a predetermined position on the paper.

[0028] Transfer roller 35 generates an electric field at the nip. As the paper enters the nip and passes through it, the toner image formed on transfer belt 30 is transferred to the paper by the action of the electric field force generated at the nip. The paper with the transferred toner image is transported along the transport path to fixing roller 36. Fixing roller 36 heats and presses the paper as it transports it. The paper and the toner image transferred to it are heated and pressurized by fixing roller 36 as it passes through fixing roller 36. This melts the toner and fixes the toner image to the paper. The paper transported by fixing roller 36 is then transported along the transport path to discharge roller 37. Discharge roller 37 discharges the paper to paper output tray 39.

[0029] Here, an example will be described in which the MFP 1 employs a tandem system in which development units 20Y, 20M, 20C, and 20K form four color toners on the transfer belt 30. Alternatively, the MFP 1 may employ a four-cycle system in which one photosensitive drum transfers the four color toners onto the paper in sequence.

[0030] FIG. 3 is a perspective view showing an example of a paper feed cassette. FIG. 4 is a plan view showing an example of a paper feed cassette. Referring to FIGS. 3 and 4, paper feed cassette 51 has a storage space for stacking and storing sheets of paper, such as cut paper, before images are formed on them. Paper feed cassette 51 is formed in the shape of a flat box with an open top, and has bottom 53A having a rectangular inner bottom surface 53 and four side walls 51A, 51B, 51C, and 51D extending upward from each of the four sides of inner bottom surface 53. Paper is stacked and stored in paper feed cassette 51 from the top surface. The paper is fed out toward the left of paper feed cassette 51 (from the positive side to the negative side in the X direction).

[0031] A push-up plate 55 is disposed on the inner bottom surface 53 of the paper feed cassette 51. Paper sheets are placed on the push-up plate 55 and stacked up. The push-up plate 55 is supported on the inner bottom surface 53 by a push-up plate shaft 56 provided at the end on the upstream side in the paper feed direction. The paper feed direction is to the left of the left-right direction (from the positive side to the negative side in the X direction). The push-up plate shaft 56 extends in the front-to-rear direction that intersects with the paper feed direction. The push-up plate 55 rotates around the push-up plate shaft 56. The push-up plate 55 can swing around the push-up plate shaft 56. The end of the push-up plate 55 opposite the push-up plate shaft 56 is the free end. The tilt angle of the push-up plate 55 in the paper feed direction changes depending on the amount of paper stacked on its upper surface by the push-up portion 65.

[0032] The paper feed cassette 51 has a first side restriction plate 52A and a second side restriction plate 52B, each having a surface perpendicular to the Y direction. The first side restriction plate 52A and the second side restriction plate 52B engage with a guide rail 52C formed on the inner bottom surface 53. The guide rail 52C extends in the front-rear direction (Y direction). The first side restriction plate 52A and the second side restriction plate 52B are guided by the guide rail 52C and are movable in the front-rear direction. The positions of the first side restriction plate 52A and the second side restriction plate 52B on the guide rail 52C are adjusted by the user to match the front-rear length of the paper sheets placed on the push-up plate 55. The first side restriction plate 52A and the second side restriction plate 52B abut against the front and rear end faces of the stack of paper sheets, respectively. In this way, the first side restriction plate 52A and the second side restriction plate 52B restrict the position of the paper sheets in the front-rear direction (Y direction).

[0033] Furthermore, a rear end regulating plate 52D is disposed upstream in the paper feed direction of the sheets loaded on the upper surface of the push-up plate 55. The rear end regulating plate 52D is movable in the paper feed direction. The user adjusts the position of the rear end regulating plate 52D in the paper feed direction to match the length in the paper feed direction of the sheets placed on the push-up plate 55. The rear end regulating plate 52D abuts against the rear end in the paper feed direction of the sheets placed on the upper surface of the push-up plate 55. In this way, the rear end regulating plate 52D regulates the position of the rear end in the paper feed direction of the sheets. The position of the rear end regulating plate 52D is adjusted by the user to match the length in the left-right direction (X direction) of the sheets placed on the push-up plate 55.

[0034] The paper feed cassette 51 has a lift-up mechanism M1 that lifts up the push-up plate 55. The lift-up mechanism M1 includes a rotating shaft 63, a push-up portion 65, and a connection receiving portion 67. The rotating shaft 63 is rotatably supported on the rear sidewall 51B of the paper feed cassette 51. The rotating shaft 63 has a shape that extends in the front-rear direction along the inner bottom surface 53 and is rotatable around the axis extending in the front-rear direction. The push-up portion 65 is attached to the front end of the rotating shaft 63. The push-up portion 65 is located in the center of the push-up plate 55 in the front-rear direction, with one end attached to the rotating shaft 63 and the other end in contact with the underside of the push-up plate 55. The push-up portion 65 is rotatable relative to the rotating shaft 63 within a predetermined angle range. Therefore, the push-up portion 65 does not rotate together with the rotating shaft 63 when the rotating shaft 63 rotates within the predetermined angle range. On the other hand, when the rotation angle of the rotary shaft 63 exceeds the predetermined range, the push-up portion 65 rotates together with the rotary shaft 63. The rear end of the rotary shaft 63 penetrates the rear side wall 51B of the paper feed cassette 51 and protrudes further rearward from the side wall 51B. A connection receiving portion 67 is fixed to the rear end of the rotary shaft 63.

[0035] A driving unit 71 is fixed to the housing 1A of the MFP 1. The driving unit 71 is fixed to the housing 1A at a position opposite to the rear end of the rotation shaft 63. The driving unit 71 has a built-in motor as a driving source.

[0036] Fig. 5 is a perspective view showing an example of a drive unit. Referring to Fig. 5, drive unit 71 has a transmission unit 73 that protrudes forward from the front surface. Drive unit 71 incorporates a motor as a drive source, a drive shaft, and a gear that transmits the driving force of the motor to the drive shaft. Transmission unit 73 is fixed to the drive shaft of drive unit 71. Transmission unit 73 is cylindrical, and has four axially extending grooves 74 formed at positions spaced 90 degrees apart in the circumferential direction.

[0037] 6 is a perspective view showing an example of the connection between a lift-up mechanism and a drive unit. Referring to FIG. 6, a lift-up mechanism M1 has a connection receiving portion 67 fixed to a rotating shaft 63 that engages with a transmission portion 73 provided on a drive unit 71. The connection receiving portion 67 has two engagement pins 69 provided at positions 180 degrees apart in the circumferential direction of the rotating shaft 63. The two engagement pins 69 protrude radially outward from the outer periphery of the rotating shaft 63. When the connection receiving portion 67 and the transmission portion 73 engage with each other, the two engagement pins 69 of the connection receiving portion 67 fit into two of four grooves 74 formed in the transmission portion 73.

[0038] When the connection receiving portion 67 is not receiving a driving force from the transmission portion 73, the push-up portion 65 is in a standby position in which the tip on the side opposite to the portion connected to the rotation shaft 63 is at the lowest position.

[0039] Fig. 7 is a first plan view schematically showing an example of a boost plate in the standby position and its periphery. Fig. 8 is a first side view schematically showing an example of a boost plate in the standby position and its periphery. With reference to Figs. 7 and 8, boost portion 65 has two through holes 66 formed in a region overlapping with rotation shaft 63 in a plan view. Through holes 66 are formed near the end of boost portion 65 on the positive side in the X direction and at positions spaced a predetermined distance apart in the Y direction. Through holes 66 have a predetermined length in the X direction.

[0040] Two first protrusions 85 are attached to the rotating shaft 63 of the lift-up mechanism M1. The first protrusions 85 are protrusions that extend radially outward from the side surface of the rotating shaft 63. Here, the first protrusions 85 have a rectangular prism shape. The two first protrusions 85 are attached to the rotating shaft 63 at positions that respectively correspond to two through holes 66 formed in the push-up section 65. The length of the two first protrusions 85 in the X direction is shorter than the length of the two through holes 66 in the X direction, and the length of the two first protrusions 85 in the Y direction is shorter than the length of the two through holes 66 in the Y direction. Therefore, each of the two first protrusions 85 fits into a corresponding one of the two through holes 66.

[0041] Here, the angle by which the rotating shaft 63 rotates from a state in which the connection receiving portion 67 is not receiving a driving force from the transmission portion 73 is referred to as the operating angle. Furthermore, the surface of the push-up portion 65 that forms the through-hole 66 on the positive side in the X direction is referred to as the abutment surface. As shown in FIG. 8 , the rotating shaft 63 is biased clockwise in FIG. 8 by a spring. When the connection receiving portion 67 is not receiving a driving force from the transmission portion 73, a gap is formed between the first protrusion 85 provided on the rotating shaft 63 and the abutment surface. The operating angle from when the rotating shaft 63 starts to rotate counterclockwise as indicated by the arrow in FIG. 8 to when the first protrusion 85 abuts on the abutment surface is referred to as the release angle θ1. From when the rotating shaft 63 starts to rotate until when the first protrusion 85 abuts on the abutment surface, the push-up portion 65 does not rotate and maintains a standby position in which the tip of the push-up portion 65 is positioned at the lowest position. Furthermore, the maximum operating angle while the push-up portion 65 maintains the standby position is referred to as the release angle θ1.

[0042] The sheet feed cassette 51 includes a release portion 80 and a fixing portion 90. The fixing portion 90 includes an engaging portion 91, a locking member 92, a locking member shaft 93, and a spring 94. The engaging portion 91 has a connecting portion that extends downward from the lower surface of the push-up plate 55, and an engaging protrusion 91A that extends in the positive X-direction at the lower end of the connecting portion.

[0043] The locking member shaft 93 is fixed to the bottom 53A. The locking member shaft 93 extends upward from the inner bottom surface 53. The locking member 92 is a plate-shaped member extending in the Y direction and is attached to the locking member shaft 93 so as to be rotatable about its axis. The locking member shaft 93 moves between an engaged position and a disengaged position by rotating about its axis. A first end of the locking member 92 on the negative side in the Y direction is connected to one end of a spring 94. The other end of the spring 94 is fixed to the side wall 51D on the negative side in the X direction. The spring 94 biases the first end of the locking member 92 in a direction toward the side wall 51D. As a result, the locking member 92 rotates counterclockwise around the axis of the locking member shaft 93, as indicated by the arrow in FIG. 7 . The locking member 92 has an engaging portion 92A and a pressed portion 92B at both ends.

[0044] When the push-up part 65 is in the standby position, the engaging protrusion 91A of the engaging part 91 is positioned below the engaging part 92A of the locking member 92. The locking member 92 is biased by the spring 94 to rotate in a direction in which the first end approaches the side wall 51D, but stops when the engaging part 92A is positioned above the engaging protrusion 91A and abuts against the engaging part 91. The position of the locking member 92 when the engaging part 92A is positioned above the engaging protrusion 91A and abuts against the engaging part 91 is the engaged position. As a result, the push-up part 65 is fixed to the inner bottom surface 53 in the standby position.

[0045] The release portion 80 includes a second protrusion 81 and a link member 82. The second protrusion 81 is provided on the side surface of the rotating shaft 63 at a different position in the circumferential direction from the first protrusion 85. In this embodiment, the second protrusion 81 is provided on the side surface of the rotating shaft 63 on the opposite side from the position where the first protrusion 85 is provided. The second protrusion 81 is a protrusion that extends outward in the radial direction from the side surface of the rotating shaft 63. Here, the second protrusion 81 has a square prism shape.

[0046] The second protrusion 81 has an end opposite to the end connected to the rotation shaft 63, which is connected to the link member 82. The second protrusion 81 and the link member 82 are connected by a common connecting shaft. Therefore, the second protrusion 81 and the link member 82 are each rotatable around the axis of the connecting shaft. The link member 82 has a pressing portion 82A at the end opposite to the end connected to the connecting shaft. The pressing portion 82A of the second protrusion 81 is attached to the inner bottom surface 53 in a state where it can slide on the inner bottom surface 53 in the X direction. For example, the pressing portion 82A of the link member 82 is attached slidably in a groove formed in the inner bottom surface 53. The pressing portion 82A abuts against a pressed portion 92B of the locking member 92.

[0047] Fig. 9 is a second plan view showing an example of the boost plate and its periphery in the standby position. Fig. 10 is a second side view showing an example of the boost plate and its periphery in the standby position. Figs. 9 and 10 show the state in which the operating angle of the rotation shaft 63 is at release angle θ1.

[0048] When the rotation shaft 63 rotates from the operating angle of 0 degrees to the release angle θ1, the end of the second protrusion 81 opposite the end connected to the rotation shaft 63 moves from the positive side to the negative side in the X direction. Accordingly, the pressing portion 82A of the link member 82 moves along the inner bottom surface 53 from the positive side to the negative side in the X direction, as indicated by the arrow in FIG. 9 . As the pressing portion 82A of the link member 82 moves, the pressed portion 92B of the locking member 92 moves toward the negative side in the X direction due to the pressing portion 82A, causing the locking member 92 to rotate clockwise, as indicated by the arrow in FIG. 9 , around the axis of the locking member shaft 93. As the locking member 92 rotates, the engaging portion 92A moves toward the positive side in the X direction, as indicated by the arrow in FIG. 9 , and the engaging portion 92A no longer overlaps with the engaging protrusion 91A of the engaging portion 91 in a plan view, resulting in disengagement. The disengagement position is the position of the locking member 92 when the engaging portion 92A does not overlap with the engaging protrusion 91A of the engaging portion 91 in a plan view. This releases the state in which the boost portion 65 is fixed to the inner bottom surface 53. Therefore, when the rotation shaft 63 is at the release angle θ1, the boost plate 55 is released from its fixed state to the inner bottom surface 53 while maintaining the standby position. By releasing the state in which the boost plate 55 is fixed to the inner bottom surface 53, the boost portion 65 can move to the push-up position in which it pushes up the boost plate 55 upward.

[0049] FIG. 11 is a plan view schematically illustrating an example of a push-up plate in the push-up position and its periphery. FIG. 12 is a side view schematically illustrating an example of a push-up plate in the push-up position and its periphery. When the operating angle of the rotation shaft 63 is the release angle θ1, the first protrusion 85 abuts against the push-up portion 65. When the operating angle of the rotation shaft 63 exceeds the release angle θ1, the first protrusion 85 rotates the push-up portion 65, and the tip of the push-up portion 65 opposite the part connected to the rotation shaft 63 rises. When the tip of the push-up portion 65 opposite the part connected to the rotation shaft 63 rises, the tip of the push-up portion 65 abuts against the underside of the push-up plate 55, and the push-up position is assumed, pushing the push-up plate 55 upward.

[0050] <Modification> Fig. 13 is a first plan view schematically showing an example of a boost plate and its periphery in a modified example. Fig. 13 shows a state in which the boost plate is in a standby position and the operating angle of the rotation shaft 63 is 0 degrees. Referring to Fig. 13, the boost portion 65, the rotation shaft 63, the first protrusion 85, and the second protrusion 81 have the same configurations as those shown in Figs. 7 to 12. Therefore, the following description will mainly focus on the parts that differ from the configurations shown in Figs. 7 to 12.

[0051] The paper feed cassette 51 in this modified example includes a release portion 80 and a fixed portion 90. The fixed portion 90 includes a first locking member 96A, a second locking member 96B, and a spring 95. The first locking member 96A and the second locking member 96B are configured symmetrically with respect to the XZ plane. Here, the first locking member 96A will be described as an example.

[0052] The first locking member 96A has a base portion 97A, a restricting portion 98A, and a pressed portion 99A. The base portion 97A has a rectangular prism shape extending in the Y direction and is attached to the inner bottom surface 53 so as to be slidable in the Y direction. The restricting portion 98A and the pressed portion 99A are provided at both ends of the base portions 97A and 97B. The restricting portion 98A has a connecting portion extending upward from the end of the base portion 97A on the positive side in the Y direction, and a bent portion extending from the connecting portion above the push-up plate 55 to the negative side in the Y direction. The bent portion has an engaging surface facing downward. The pressed portion 99A has a pressed surface that is parallel to the Z direction and intersects with the X and Y directions. The pressed surface is a surface facing the positive side in the X direction.

[0053] The spring 95 connects the first locking member 96A and the second locking member 96B. The spring 95 biases the first locking member 96A and the second locking member 96B in directions that bring them closer to each other. Therefore, when the operating angle of the rotation shaft 63 is 0 degrees, the distance between the first locking member 96A and the second locking member 96B is shortest.

[0054] When the booster section 65 is in the standby position and the distance between the first locking member 96A and the second locking member 96B is at its shortest, a portion of each of the bent portions of the restricting section 98A of the first locking member 96A and the bent portion of the restricting section 98B of the second locking member 96B overlaps with and above the booster plate 55. Therefore, the booster plate 55 is fixed to the inner bottom surface 53 by the first locking member 96A and the second locking member 96B.

[0055] The first locking member 96A and the second locking member 96B can each move in the Y direction between an engaged position and a disengaged position. When the first locking member 96A is in the engaged position, the bent portion of the restricting portion 98A of the first locking member 96A overlaps with the boost plate 55 above it. When the first locking member 96A is in the disengaged position, the bent portion of the restricting portion 98A of the first locking member 96A does not overlap with the boost plate 55 above it. Similarly, when the second locking member 96B is in the engaged position, the bent portion of the restricting portion 98B of the second locking member 96B overlaps with the boost plate 55 above it. When the second locking member 96B is in the disengaged position, the bent portion of the restricting portion 98B of the second locking member 96B does not overlap with the boost plate 55 above it.

[0056] The release portion 80 includes a second protrusion 81 and a pressing member 86. The second protrusion 81 is provided on the side surface of the rotating shaft 63 at a different position in the circumferential direction from the first protrusion 85. In this embodiment, the second protrusion 81 is provided on the opposite side from the position where the first protrusion 85 is provided. The second protrusion 81 is a protrusion that extends outward in the radial direction from the side surface of the rotating shaft 63. Here, the second protrusion 81 has a square prism shape.

[0057] The second protrusion 81 has an end opposite to the end connected to the rotation shaft 63, which is connected to the pressing member 86. The second protrusion 81 and the pressing member 86 are connected by a common connecting shaft. Therefore, the second protrusion 81 and the pressing member 86 are each rotatable around the axis of the connecting shaft. The pressing member 86 has a pressing portion 87 at the end opposite to the end connected to the connecting shaft. The pressing portion 87 is attached to the inner bottom surface 53 in a state where it can slide on the inner bottom surface 53 in the X direction. For example, the pressing member 86 has the pressing portion 87 attached to a groove formed in the inner bottom surface 53 so as to be slidable. The pressing portion 87 abuts against a pressed portion 99A of the first locking member 96A and a pressed portion 99B of the second locking member 96B. The pressing portion 87 has a first pressing surface facing the pressed surface of the pressed portion 99A of the first locking member 96A, and a second pressing surface facing the pressed surface of the pressed portion 99B of the second locking member 96B. When the pushing portion 65 is in the standby position and the operating angle of the rotation shaft 63 is 0 degrees, the first pressing surface abuts against the pressed surface of the pressed portion 99A of the first locking member 96A, and the second pressing surface abuts against the pressed surface of the pressed portion 99B of the second locking member 96B.

[0058] Fig. 14 is a second plan view schematically showing an example of the boost plate and its periphery in a modified example, in which the boost plate is in the standby position and the operating angle of the rotation shaft 63 is the release angle θ1.

[0059] When the rotation shaft 63 rotates from the operating angle of 0 degrees to the release angle θ1, the end of the second protrusion 81 opposite the end connected to the rotation shaft 63 moves from the positive side to the negative side in the X direction. Accordingly, the pressing portion 87 of the pressing member 86 moves along the inner bottom surface 53 from the positive side to the negative side in the X direction, as indicated by the arrow in FIG. 14 . As the pressing portion 87 of the pressing member 86 moves, the pressing portion 87 presses the pressed portion 99A of the first locking member 96A in the negative side in the X direction, and the pressing portion 87 presses the pressed portion 99B of the second locking member 96B in the negative side in the X direction. The pressed surface of the pressed portion 99A of the first locking member 96A and the second pressing surface of the pressed portion 99B of the second locking member 96B are parallel to the Z direction and intersect with the X and Y directions. 14, the first locking member 96A moves in the positive direction of the Y direction, and the second locking member 96B moves in the negative direction of the Y direction. As the first locking member 96A and the second locking member 96B move, the bent portions of the restricting portion 98A of the first locking member 96A and the bent portions of the restricting portion 98B of the second locking member 96B no longer overlap with the push-up plate 55 above them. As a result, the push-up plate 55 is released from being fixed to the inner bottom surface 53 by the first locking member 96A and the second locking member 96B.

[0060] <Other variations> In the present embodiment, an MFP 1 has been described as an example of an image forming apparatus, but the present invention is not limited to this. The image forming apparatus may also be a printer or a facsimile machine. Furthermore, the image forming function is not limited to an electrophotographic method that forms images using toner, but may also be an inkjet method that forms images using ink.

[0061] As described above, in the paper feed cassette 51 of the present embodiment, the fixation of the push-up plate 55 to the inner bottom surface 53 by the fixing portion 90 is released in conjunction with the lift-up mechanism M1. Therefore, the push-up plate 55 is pushed up after the fixation of the push-up plate 55 to the inner bottom surface 53 is released. In other words, the push-up plate 55 fixed to the inner bottom surface 53 can be prevented from being pushed up. Therefore, excessive loads can be prevented from being applied to the push-up plate 55, the fixing portion 90, and the lift-up mechanism M1, and breakdowns can be suppressed.

[0062] Furthermore, the fixing portion 90 fixes the push-up plate 55 to the inner bottom surface 53 while the lift-up mechanism M1 is not pushing up the push-up plate 55. Therefore, while the fixing portion 90 fixes the push-up plate 55 to the inner bottom surface 53, the push-up plate 55 can be prevented from being pushed up.

[0063] Furthermore, the lift-up mechanism M1 and the release unit 80 are each driven by a drive unit 71 provided in the MFP 1, and the release unit 80 releases the fixation of the push-up plate 55 before the push-up plate 55 is pushed up by the lift-up mechanism M1 after the drive unit 71 has operated. This prevents the lift-up plate 55 from being pushed up by the lift-up mechanism M1 before the fixation of the push-up plate 55 is released.

[0064] Furthermore, paper feed cassette 51 is slidable relative to housing 1A of MFP 1 between an open state and a closed state, and lift-up mechanism M1 and release unit 80 are each connected to drive unit 71 in the closed state and are not connected to drive unit 71 in the open state. Therefore, while lift-up mechanism M1 is not connected to drive unit 71, lift-up mechanism M1 does not push up push-up plate 55, and push-up plate 55 is fixed to inner bottom surface 53 by fixing unit 90. Therefore, in the open state, push-up plate 55 can be fixed to inner bottom surface 53, and in the closed state, push-up plate 55 can be pushed up.

[0065] The lift-up mechanism M1 includes a rotating shaft 63, a first protrusion 85, and a push-up portion 65 that changes the posture of the push-up plate 55. The push-up plate 55 has an abutment surface that abuts against the first protrusion 85 as the rotating shaft 63 rotates. The release portion 80 includes a second protrusion 81 that is formed on the rotating shaft 63 and protrudes radially at a circumferentially different position from the first protrusion 85, and a link member 82 that is connected to the second protrusion 81 and releases the fixation by the fixing portion 90. The abutment surface is a surface that forms the through hole 66 in the push-up portion 65. Therefore, the positions at which the first protrusion 85 and the second protrusion 81 are disposed circumferentially about the rotating shaft 63 can be adjusted. This allows the timing at which the push-up plate 55 is pushed up relative to the rotation of the rotating shaft 63 to differ from the timing at which the release portion 80 releases the push-up plate 55 from the inner bottom surface 53.

[0066] The abutment surface does not abut against the first protrusion 85 from when the rotary shaft 63 starts to rotate until the link member 82 is released from fixation by the fixing portion 90. Therefore, after fixation by the fixing portion 90 is released, the push-up plate 55 is pushed up by the first protrusion 85, which rotates around the axis of the rotary shaft 63. Therefore, after the fixation of the push-up plate 55 to the inner bottom surface 53 is released, the push-up plate 55 can be pushed up.

[0067] The fixing portion 90 has a locking member 92 that is movable between an engagement position where it engages with the boost plate 55 and a disengagement position where it does not engage, and the paper feed cassette 51 has a spring 94 that urges the locking member 92 toward the engagement position. In the paper feed cassette 51 of the modified example, the fixing portion 90 has a first locking member 96A and a second locking member 96B that are movable between an engagement position where it engages with the boost plate 55 and a disengagement position where it does not engage. The paper feed cassette 51 of the modified example has a spring 95 that urges each of the first locking member 96A and the second locking member 96B toward the engagement position. Therefore, the boost plate 55 can be fixed to the inner bottom surface 53 while the release portion 80 is releasing the fixation of the boost plate 55 to the inner bottom surface 53.

[0068] When the lift-up mechanism M1 and the release unit 80 are connected to the drive unit 71, the drive unit 71 operates to change the state of the sheet feed cassette 51 from the first state to the second state. The first state is a state in which the drive force of the drive unit 71 is transmitted to the release unit 80 but not to the lift-up mechanism M1. The second state is a state in which the drive force of the drive unit 71 is transmitted to the lift-up mechanism M1. Therefore, the single drive unit 71 can release the fixation by the fixation unit 90 and operate the lift-up mechanism M1.

[0069] Furthermore, the fixing portion 90 fixes the boost plate 55 to the inner bottom surface 53 in a state where no driving force is transmitted from the driving portion 71. Therefore, the boost plate 55 can be fixed to the inner bottom surface 53 without receiving a driving force from the driving portion 71.

[0070] <Summary of implementation form> (Item 1) A paper feed cassette to be installed in an image forming apparatus, a push-up plate disposed on the inner bottom surface and on which the recording medium is placed; a lift-up mechanism for lifting up the lift-up plate; a fixing portion that fixes the push-up plate to the inner bottom surface; a release portion that, in conjunction with the lift-up mechanism, releases the fixation of the push-up plate by the fixation portion.

[0071] According to this aspect, the fixation of the push-up plate to the inner bottom surface by the fixing portion is released in conjunction with the lift-up mechanism. The push-up plate is pushed up after the fixation of the push-up plate to the inner bottom surface is released. This prevents the push-up plate from being pushed up while it is fixed to the inner bottom surface. This prevents excessive load from being applied to the push-up plate, the fixing portion, and the lift-up mechanism. As a result, a paper feed cassette with reduced malfunctions can be provided.

[0072] (Item 2) The paper feed cassette according to item 1, wherein the fixing portion fixes the push-up plate to the inner bottom surface while the lift-up mechanism is not pushing up the push-up plate.

[0073] The fixing portion fixes the boost plate to the inner bottom surface while the lift-up mechanism is not pushing up the boost plate, so that the boost plate cannot be pushed up while the fixing portion fixes the boost plate to the inner bottom surface.

[0074] (Item 3) The lift-up mechanism and the release unit are each driven by a drive unit provided in the image forming apparatus, Item 2. The paper feed cassette according to item 1, wherein the release unit releases the fixation of the push-up plate after the drive unit operates and before the push-up plate is pushed up by the lift-up mechanism.

[0075] According to this aspect, the lift-up mechanism and the release unit are each driven by a drive unit provided in the image forming apparatus, and after the drive unit operates, the fixation of the push-up plate is released before the push-up plate is pushed up by the lift-up mechanism. Therefore, the push-up plate can be prevented from being pushed up by the lift-up mechanism before the fixation of the push-up plate is released.

[0076] (Item 4) The door is slidable relative to the housing of the image forming apparatus between an open state and a closed state, Item 4. The paper feed cassette according to item 3, wherein the lift-up mechanism and the release unit are connected to the drive unit in the closed state and are not connected to the drive unit in the open state.

[0077] According to this aspect, the lift-up mechanism and the release unit are each connected to the drive unit in the closed state and not connected to the drive unit in the open state. Therefore, while the lift-up mechanism is not connected to the drive unit, the lift-up mechanism does not push up the boost plate, and the boost plate is fixed to the inner bottom surface by the fixing unit. Therefore, the boost plate can be fixed to the inner bottom surface in the open state and can be pushed up in the closed state.

[0078] (Item 5) The lift-up mechanism includes a rotary shaft disposed below the lift-up plate; a first protrusion protruding radially from the rotary shaft; a push-up portion having a contact surface that contacts the first protrusion as the rotation shaft rotates and that changes the attitude of the push-up plate, The release portion includes a second protrusion formed on the rotating shaft and protruding in a radial direction at a position different from the first protrusion in a circumferential direction; 5. The sheet feed cassette according to any one of items 1 to 4, further comprising: a link member connected to the second protrusion, for releasing the fixation by the fixing portion.

[0079] According to this aspect, the first protrusion and the second protrusion rotate about the rotation shaft as the rotation shaft rotates. The push-up portion has an abutment surface that abuts against the first protrusion, and the link member is connected to the second protrusion. Therefore, by adjusting the positions of the first protrusion and the second protrusion in the circumferential direction of the rotation shaft, it is possible to differentiate the timing at which the push-up plate is pushed up relative to the rotation of the rotation shaft from the timing at which the release portion releases the fixation of the push-up plate to the inner bottom surface.

[0080] (Item 6) The paper feed cassette according to item 5, wherein the contact surface does not contact the first protrusion from when the rotation shaft starts to rotate until when the link member is released from the fixing portion.

[0081] According to this aspect, the abutment surface does not abut against the first protrusion from when the rotation shaft starts to rotate until the link member is released from the fixation by the fixation part. Therefore, after the fixation by the fixation part is released, the first protrusion, which rotates around the rotation shaft, pushes up the boost plate. Therefore, the boost plate can be pushed up after the fixation to the inner bottom surface is released.

[0082] (Item 7) The fixing portion has an engaging portion that is movable between an engaging position where it engages with the lifting plate and a non-engaging position where it does not engage with the lifting plate, 7. The paper feed cassette according to any one of items 1 to 6, further comprising a biasing portion that biases the engaging portion toward the engaging position.

[0083] According to this aspect, the engaging portion is urged toward the engaging position by the urging portion, so that the engaging portion engages with the boost plate while the fixation by the releasing portion is not released. Therefore, the boost plate can be fixed to the inner bottom surface while the fixation of the boost plate to the inner bottom surface by the releasing portion is released.

[0084] (Item 8) An image forming apparatus including the paper feed cassette according to any one of items 1 to 9.

[0085] According to this aspect, it is possible to provide an image forming apparatus in which failures are suppressed.

[0086] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0087] 1 MFP, 1A housing, 11 automatic document feeder, 13 document reading unit, 15 image forming unit, 17 paper feed unit, 51 paper feed cassette, 51A to 51D side wall, 52A first side regulation plate, 52B second side regulation plate, 52C guide rail, 52D rear end regulation plate, 53 inner bottom surface, 53A bottom, 55 push-up plate, 56 push-up plate shaft, 63 rotating shaft, 65 push-up portion, 66 through hole, 67 connection receiving portion, 69 engagement pin, 71 drive portion, 73 transmission portion, 74 groove, 75 drive shaft, 80 release portion, 81 second protrusion, 82 link member, 82A pressing portion, 85 first protrusion, 86 pressing member, 87 pressing portion, 90 fixing portion, 91 engagement portion, 91A engagement convex portion, 92 Locking member, 92A: engaging portion, 92B: pressed portion, 93: locking member shaft, 94, 95: spring, 96A: first locking member, 96B: second locking member, 97A, 97B: base portion, 98A, 98B: restricting portion, 99A, 99B: pressed portion, M1: lift-up mechanism.

Claims

1. A paper feed cassette to be installed in an image forming apparatus, a push-up plate disposed on the inner bottom surface and on which a recording medium is placed; a lift-up mechanism for lifting up the lift-up plate; a fixing portion that fixes the push-up plate to the inner bottom surface; a release portion that, in conjunction with the lift-up mechanism, releases the fixation of the push-up plate by the fixation portion.

2. The paper feed cassette according to claim 1 , wherein the fixing portion fixes the push-up plate to the inner bottom surface while the lift-up mechanism is not pushing up the push-up plate.

3. the lift-up mechanism and the release unit are each driven by a drive unit provided in the image forming apparatus, 2. The paper feed cassette according to claim 1, wherein the release section releases the fixation of the push-up plate after the drive section operates and before the push-up plate is pushed up by the lift-up mechanism.

4. The door is slidable relative to the housing of the image forming apparatus between an open state and a closed state, The paper feed cassette according to claim 3 , wherein the lift-up mechanism and the release section are connected to the drive section in the closed state, and are not connected to the drive section in the open state.

5. The lift-up mechanism includes a rotation shaft disposed below the lift-up plate; a first protrusion protruding radially from the rotary shaft; a push-up portion having a contact surface that contacts the first protrusion as the rotation shaft rotates and that changes the attitude of the push-up plate, The release portion includes a second protrusion formed on the rotary shaft and protruding in a radial direction at a position different from the first protrusion in a circumferential direction; The paper feed cassette according to claim 1 , further comprising: a link member connected to the second protrusion for releasing the fixing by the fixing portion.

6. The paper feed cassette according to claim 5 , wherein the contact surface does not contact the first protrusion from when the rotation shaft starts to rotate until when the link member is released from the fixing portion.

7. the fixing portion has an engaging portion that is movable between an engaging position where it engages with the lifting plate and a disengaging position where it does not engage with the lifting plate, 7. The paper feed cassette according to claim 1, further comprising a biasing portion that biases the engaging portion toward the engaging position.

8. 7. An image forming apparatus comprising the paper feed cassette according to claim 1.

Images