JP6411196B2 - Paper feeding device, paper feeding method, and image forming apparatus - Google Patents

Description

  The present invention relates to a paper feeding device, a paper feeding method, and an image forming apparatus.

  As a paper feeding device that feeds paper to an image forming apparatus such as a printer, a facsimile machine, or a copier, the paper placed on a paper placing table (paper feeding tray) is pressed against a roller, and the paper is rotated by rotating the roller. Paper feeders that supply one sheet at a time are widely used.

  13 and 14 are schematic sectional views of a conventional paper feeding device. FIG. 13 is a schematic cross-sectional view of a state in which a large amount of recording paper is stacked. FIG. 14 is a schematic cross-sectional view of a state in which a small amount of recording paper is stacked. A push-up mechanism is provided.

  As shown in FIG. 13, when a large amount of recording paper P is stacked on the rotating plate Q, the uppermost recording paper P is pulled out by the pickup roller R1, and the contact portion between the paper feeding roller R2 and the separation roller R3. Since the leading edge of the recording paper P is inserted into the nip area, accurate paper feeding can be performed. However, when a small amount of recording paper P is stacked on the rotating plate Q as shown in FIG. 14, only the leading end of the rotating plate Q rises, so that the angle of the leading end of the recording paper P changes. . Therefore, even when the uppermost recording paper P is pulled out by the pickup roller R1, the leading edge of the recording paper P is not accurately inserted into the nip region between the paper feed roller R2 and the separation roller R3, and the collision position and angle of the recording paper P are There has been a problem that the paper feed cannot be accurately performed due to the change and a paper feed error occurs.

  In order to keep the angle of the leading edge of the paper constant regardless of the remaining amount of recording paper, the angle change can be suppressed by arranging the rotating plate and its fulcrum as far back as possible. In addition, there was a limit to the rearward placement of the rotating plate and fulcrum.

  In order to solve these problems, Patent Document 1 is provided with a pressure lever that raises the paper feed side and a pressure lever that raises the rear end side. A paper feeding device that raises a mounting board in a horizontal state by interlocking two pressure levers and rotating them in opposite directions is disclosed.

Japanese Patent Application Laid-Open No. 11-049381

  The paper used for the image forming apparatus may not only use paper of different thickness and paper quality, but it also recycles the back side of the recording paper once printed on the surface for effective use of resources and cost reduction. Currently, printing is also used. If the paper thickness and quality are different, the edge of the paper may be warped (curled) depending on the environmental temperature and humidity, and the paper deflection until the paper tip collides with the roller may be slightly different. there were. Further, depending on the printing on the back paper and the storage condition of the paper, such warp (curl) and bending problems have occurred remarkably.

  If the paper is warped (curled) or bent, the collision position of the paper supplied to the roller and the angle of the front edge of the paper change, so that the paper cannot be accurately fed and a paper feeding error occurs. There was a problem.

  However, in the paper feeder disclosed in Patent Document 1, a horizontal state is maintained by interlocking the pressure lever with a change in weight due to the remaining amount of paper, and flexible feeding according to the type of paper and changes in the state of the paper. It was difficult to do.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and is a paper feeding device, a paper feeding method, and an image capable of flexibly supplying paper according to the type of paper and the change in the state of the paper. An object is to provide a forming apparatus.

In order to solve the above-described problems, a paper feeding device according to the present invention includes a paper placement table on which paper is placed, separation feeding means for separating and feeding the paper one by one, and the paper placement table. comprising a plurality of lifting members for moving the stacking direction of the paper, and a plurality of lifting members driving means for driving the plurality of elevating members each independently, a tilt setting unit for setting the inclination of the sheet table, the lifting The member includes a flat plate-like portion, a rotary shaft portion that is provided on the plate-like portion and pivotally supports the plate-like portion, and a support portion that supports the paper placement table movably in the stacking direction. And driving the plurality of elevating member driving means on the basis of the inclination set by the inclination setting means to control the inclination of the sheet mounting table.

In the paper feeding device according to the present invention, the rotation shaft portion is positioned on a central side with respect to the support portion in a feeding direction of feeding the paper on the paper placing table.

  In the paper feeding device of the present invention, the tilt setting unit includes a sheet detection unit that detects the state of the sheet, and sets the tilt based on a detection result of the sheet detection unit.

  In the sheet feeding device of the present invention, the inclination setting unit includes a temperature sensor that measures temperature and / or a humidity sensor that measures humidity, and the temperature sensor and / or the humidity sensor based on the measurement result. It is characterized by setting an inclination.

  In the paper feeding device of the present invention, the tilt setting means includes a paper input means for setting the paper type, and sets the tilt based on the paper type input by the paper input means. It is characterized by.

  On the other hand, the image forming apparatus of the present invention includes an image forming unit that forms an image on a sheet supplied from the sheet feeding device.

  In the paper feeding device, the paper feeding method, and the image forming apparatus according to the present invention, the inclination setting unit sets the inclination angle of the paper mounting table, and controls the inclination of the paper setting table by independently driving a plurality of lifting members. Yes. Therefore, it is possible to provide a paper feeding device, a paper feeding method, and an image forming apparatus that can flexibly supply paper according to the type of paper and changes in the state of the paper.

1 is a schematic cross-sectional view illustrating a configuration example of an image forming apparatus to which the present invention is applied. FIG. 3 is a schematic plan view of the paper feed cassette according to the first embodiment as viewed from above. It is a block diagram which shows the control part which controls rotation of a raising / lowering arm. FIG. 3 is a schematic cross-sectional view of a state in which a large amount of recording paper is stacked on the paper feed cassette according to the first embodiment. FIG. 3 is a schematic cross-sectional view of a state in which a large amount of recording paper is stacked on the paper feed cassette according to the first embodiment. It is the schematic plan view which looked at the paper feed cassette and arm drive means of a 1st embodiment from the upper part. It is a schematic sectional drawing of the state which loaded the recording paper on the paper feed cassette of 2nd Embodiment. FIG. 9 is a schematic cross-sectional view of a state in which plain recording paper is stacked on a paper feed cassette according to a third embodiment. FIG. 9 is a schematic cross-sectional view of a state in which thick recording paper is stacked on a paper feed cassette according to a third embodiment. FIG. 10 is a schematic cross-sectional view of a state in which recording paper warped upward is stacked on a paper feed cassette according to a fourth embodiment. It is a schematic sectional drawing of the state which loaded the recording paper along the downward direction on the paper feed cassette of 4th Embodiment. FIG. 10 is a schematic cross-sectional view of a state in which recording sheets stored for a long time are stacked in a sheet feeding cassette according to a fifth embodiment. FIG. 6 is a schematic cross-sectional view of a state in which a large amount of recording paper is stacked on a paper feeder using a conventional rotating plate. FIG. 6 is a schematic cross-sectional view of a state in which a small amount of recording paper is stacked on a paper feeder using a conventional rotating plate.

(First embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a configuration example of a sheet feeding device to which the present invention is applied and an image forming apparatus including the sheet feeding device will be described.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus including a sheet feeding device according to the present embodiment.

  An image forming apparatus 100 shown in FIG. 1 forms a toner image on a sheet P such as recording paper using toner.

  The apparatus main body 110 includes an image carrier (here, a photosensitive drum) 3, a charging device (here, a charger) 5 for charging the surface of the photosensitive drum 3, and an electrostatic latent image on the photosensitive drum 3. An exposure device (here, an exposure unit) 1 for forming, a developing device (here, a developing device) 2 for visualizing the electrostatic latent image with toner and forming a toner image on the photosensitive drum 3, and an intermediate A transfer body (here, an intermediate transfer body belt) 61, a primary transfer device (here, an intermediate transfer roller) 64 that temporarily transfers the toner image on the photosensitive drum 3 onto the intermediate transfer belt 61, and an intermediate transfer roller 64. A primary cleaning device (here, a cleaner unit) 4 that removes residual toner remaining on the surface of the photosensitive drum 3 without being transferred, and a secondary transfer device that transfers the toner image on the intermediate transfer belt 61 onto the sheet P. (Here, a secondary transfer unit) 10, a secondary cleaning device (here, an intermediate transfer belt cleaning unit) 65 that removes residual toner remaining on the surface of the intermediate transfer belt 61 without being transferred by the secondary transfer unit 10, A fixing device 7 for fixing the toner image formed on the sheet P by heating and melting and fixing the toner image is provided.

  In addition to the above configuration, the image forming apparatus 100 includes a conveyance path S for a sheet P, a pair of conveyance rollers 12a to 12d disposed along both sides of the conveyance path S, and an original reading apparatus that reads an image of an original. (Scanner device here) 90, a document placing table 92 on which a document is placed, and an automatic document processing device 120.

  A document reading device 90 is provided on the upper portion of the apparatus main body 110. A document placing table 92 made of transparent glass is provided on the upper side of the document reading device 90, and an automatic document processing device 120 is attached on the upper side of the document placing table 92. The automatic document processing device 120 automatically conveys the document onto the document reading device 90. Further, the automatic document processing device 120 is rotatable about a pivot shaft along the document conveyance direction so that the document can be manually placed by opening the document placing table 92. It has become. As a result, the document reading device 90 can read the image of the document conveyed by the automatic document processing device 120 or the image of the document placed on the document placing table 92.

  The image forming apparatus 100 forms multicolor and single color images on the sheet P in accordance with image data corresponding to the document read by the document reading device 90 or image data transmitted from the outside. It is configured.

  More specifically, the image data handled in the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y), or a single color. This corresponds to a monochrome image using (for example, black). Accordingly, four each of the developing device 2, the photosensitive drum 3, the charger 5, the cleaner unit 4, and the intermediate transfer roller 64 are provided to form four types of images corresponding to the respective colors.

  That is, these four members are set to black, cyan, magenta, and yellow, respectively, and an image station is configured by these members.

  The charger 5 is a charging unit for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. As the charger 5, a contact type charger (for example, a roller type or a brush type) or a charger type charger as shown in FIG. 1 can be used.

  The exposure unit 1 has a function of forming an electrostatic latent image corresponding to image data on the surface by exposing the surface of the charged photosensitive drum 3 according to input image data. . Specifically, the exposure unit 1 includes a polygon mirror that scans a laser beam and optical elements such as a lens and a mirror for guiding the laser beam reflected by the polygon mirror to the photosensitive drum 3.

  As the exposure unit 1, a laser scanning unit (LSU) including a laser irradiation unit and a reflection mirror, or a writing device (for example, a writing head) in which light emitting elements such as EL and LED are arranged in an array can be used.

  The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toners of four colors (Y, M, C, K). The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  An intermediate transfer belt unit 6 is disposed above the photosensitive drum 3. The intermediate transfer belt unit 6 includes an intermediate transfer belt driving roller 62 and an intermediate transfer belt driven roller 63 in addition to the intermediate transfer belt 61, the intermediate transfer roller 64, and the intermediate transfer belt cleaning unit 65 described above.

  The intermediate transfer belt driving roller 62, the intermediate transfer roller 64, the intermediate transfer belt driven roller 63, and other rollers stretch and support the intermediate transfer belt 61, and the surface of the intermediate transfer belt 61 is directed in a predetermined direction (in the direction of arrow D in the figure) ) Can be moved.

  The intermediate transfer roller 64 is rotatably supported on the side opposite to the photosensitive drum 3 with the intermediate transfer belt 61 interposed therebetween. The intermediate transfer roller 64 gives a transfer bias to the intermediate transfer belt 61 for the toner image on the photosensitive drum 3.

  The intermediate transfer belt 61 is provided so as to be in contact with each photosensitive drum 3, and each color toner image formed on the photosensitive drum 3 is sequentially superimposed and transferred onto the intermediate transfer belt 61. Thus, a color toner image (multicolor toner image) is formed on the intermediate transfer belt 61. Here, the intermediate transfer belt 61 is formed endlessly using a film having a thickness of about 100 μm to 150 μm.

  The toner image is transferred from the photosensitive drum 3 to the intermediate transfer belt 61 by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61 (that is, the side opposite to the photosensitive drum 3 of the intermediate transfer belt 61). Done. The intermediate transfer roller 64 has a high-voltage transfer bias for transferring the toner image to the intermediate transfer belt 61, that is, a high-voltage transfer having a polarity (for example, a positive electrode) opposite to the toner charging polarity (for example, a negative electrode). A bias is applied. Here, the intermediate transfer roller 64 is based on a rotating shaft made of a metal having a diameter of 8 mm to 10 mm (for example, stainless steel), and the surface thereof is made of a conductive elastic material (for example, a material such as EPDM or urethane foam). ). The intermediate transfer roller 64 can apply a high voltage uniformly to the intermediate transfer belt 61 by the conductive elastic material. In this embodiment, a roller-shaped transfer electrode is used. However, the present invention is not limited to this, and a brush-shaped electrode can also be used.

  As described above, the toner images visualized by the toners of the respective colors on the photosensitive drum 3 are stacked on the intermediate transfer belt 61. The toner images of the respective colors stacked in this manner are transferred onto the sheet P by the secondary transfer unit 10 disposed at a transfer portion where the sheet P and the intermediate transfer belt 61 face each other by the rotation of the intermediate transfer belt 61. .

  The intermediate transfer belt 61 and the transfer roller 10a of the secondary transfer unit 10 are pressed against each other to form a nip region. Further, the transfer roller 10a of the secondary transfer unit 10 has a voltage (that is, a polarity opposite to the charging polarity of the toner (for example, a negative electrode) for transferring the toner image of each color on the intermediate transfer belt 61 onto the sheet P, that is, For example, a positive electrode) voltage is applied. Further, in order to constantly obtain the nip region, either the roller of the secondary transfer unit 10 or the intermediate transfer belt drive roller 62 is made of a hard material such as a metal roller, and the other is a soft material such as an elastic roller. (For example, soft materials such as elastic rubber and foamable resin).

  By the way, the toner image of each color on the intermediate transfer belt 61 may not be completely transferred onto the sheet P by the secondary transfer unit 10, and the toner may remain on the intermediate transfer belt 61. This residual toner causes toner color mixing in the next step.

  Therefore, the intermediate transfer belt cleaning unit 65 is configured to remove and collect the residual toner. For example, the intermediate transfer belt cleaning unit 65 includes a cleaning blade that contacts the intermediate transfer belt 61 as a cleaning member. The cleaning blade is supported on the back side of the intermediate transfer belt 61 (that is, the side opposite to the driven roller 63 of the intermediate transfer belt 61) at a position facing the intermediate transfer belt driven roller 63.

  The image forming apparatus 100 further includes a paper feed cassette 81 and a discharge unit 91.

  The sheet feeding cassette 81 is for storing sheets P used for image formation, and is a sheet feeding apparatus according to this embodiment provided on the lower side of the apparatus main body 110. In addition, the discharge unit 91 is provided on the upper portion of the apparatus main body 110, and is a discharge tray in the present embodiment. The discharge unit 91 is a tray for loading the image-formed sheet P face down.

  Further, the apparatus main body 110 is provided with a substantially S-shaped main conveyance path S1 for sending the sheet P of the paper feed cassette 81 to the discharge unit 91 via the secondary transfer unit 10 and the fixing device 7. .

  Further, a pickup roller 11a, a paper feed roller 11b, a separation roller 11c, a registration roller 13, a secondary transfer unit 10, and a fixing device 7 are disposed along the main conveyance path S1 from the paper feed cassette 81 to the discharge unit 91. ing.

  The conveyance rollers 12 a to 12 d are, for example, small rollers for promoting and assisting the conveyance of the sheet P, and are provided along the conveyance path S. The transport path S includes a switchback transport path S2 and a reverse transport path S3 in addition to the main transport path S1.

  In the paper feed cassette 81, a pickup roller 11a provided at one upper end thereof, a paper feed roller 11b provided downstream of the pickup roller 11a in the recording paper conveyance direction, and a separation roller pressed against the paper feed roller 11b 11c. The pickup roller 11a is pressed against the uppermost recording paper (sheet P) of the paper bundle of the paper feed cassette 81, the uppermost recording paper is pulled out by rotating the pickup roller 11a, and the recording paper is fed by the paper feeding roller 11b. Transport to the main transport path S1. The pickup roller 11a, the paper feed roller 11b, and the separation roller 11c constitute the separation feeding unit 11 of the present invention.

  The registration roller 13 temporarily stops the sheet P conveyed from the sheet feeding cassette 81 and aligns the leading end of the sheet P. The registration roller 13 has a function of conveying the sheet P in a timely manner in synchronization with the toner image on the intermediate transfer belt 61.

  The fixing device 7 fixes the unfixed toner image formed on the sheet P on the sheet P by heat-melting and fixing the image.

  In the image forming apparatus 100 described above, when a single-sided image formation is requested, first, the sheet P conveyed from the paper feed cassette 81 is conveyed to the registration roller 13 by the conveyance roller 12a in the main conveyance path S1. . Next, the sheet P is conveyed to the transfer portion in synchronization with the toner image on the intermediate transfer belt 61 by the registration roller 13. The toner image on the intermediate transfer belt 61 is transferred onto the sheet P conveyed to the transfer site by a transfer electric field applied to the secondary transfer unit 10. Thereafter, the sheet P passes through the fixing device 7, whereby the unfixed toner transferred onto the sheet P receives heat and pressure, and is melted, fixed, and fixed on the sheet. Thereafter, the sheet P on which the toner image is fixed is discharged onto the discharge portion 91 via the conveyance roller 12b.

  On the other hand, when requesting double-sided image formation, as described above, the single-sided image formation is completed, and the sheet P that has passed through the fixing device 7 is conveyed while being chucked by the conveyance roller 12b in the switchback conveyance S2. When the roller 12b rotates in the reverse direction, the roller 12b is transported to the reverse transport path S3 by the transport rollers 12c and 12d so that the upstream end in the transport direction before stopping is forward. The sheet P conveyed to the reverse conveyance path S3 is guided to the upstream side in the conveyance direction from the transfer portion by the conveyance rollers 12c and 12d, and then the image is formed on the back surface through the registration roller 13 and discharged to the discharge unit 91. Is done.

  Next, the paper feed cassette 81 which is the paper feed device of this embodiment will be described in detail with reference to FIG. FIG. 2 is a schematic plan view of the paper feed cassette 81 as viewed from above.

  The sheet feeding cassette 81 has a bottom case and a side face in a box-like case member 81a that is opened upward, and elevating arms 82 and 83, a sheet placing table 84, and guide members 85a, 85b, and 85c that are elevating members. The gears 86a and 86b, the pickup roller 11a, the paper feed roller 11b, and the separation roller 11c are arranged outside the case member 81a. Although not shown in FIG. 2, the paper feed cassette 81 is provided with an inclination setting unit and a plurality of lifting member driving units.

  The elevating member is not limited to the elevating arms 82 and 83, and any structure and mechanism may be used as long as the elevating member can be moved up and down while holding the paper mounting table 84 rotatably.

  The elevating arms 82 and 83 are substantially rectangular and flat plate-like portions 82a and 83a, respectively, and substantially cylindrical rotating shaft portions 82b and 83b formed so that both ends protrude from one side of the plate-like portions 82a and 83a. The plate-like portions 82a and 83a are provided with substantially spherical support portions 82c and 83c formed in the vicinity of the corners opposite to the rotation shaft portions 82b and 83b. The two elevating arms 82 and 83 are arranged to face each other so that the rotary shaft portions 82b and 83b are located inside, and a support portion 82c is located on the rear end side of the paper feed cassette 81 and is supported on the paper feed side. The part 83c is located.

  The rotating shaft portions 82b and 83b have one end inserted into a recess formed in one side wall of the case member 81a and the other end inserted into a through-hole formed in the other side wall to protrude from the outside. It is rotatably held so as to be substantially parallel near the bottom surface of the member 81a. Gears 86a and 86b are attached to the rotating shaft portions 82b and 83b protruding from the through holes of the case member 81a, and the lifting arm 82 is centered on the rotating shaft portions 82b and 83b as the gears 86a and 86b rotate. , 83 are rotated.

  The paper mounting table 84 is a plate-like member from which the substantially rectangular regulation regions 84a, 84b, and 84c are removed. The paper mounting table 84 is placed on the lifting arms 82 and 83 and is held in contact with the support portions 82c and 83c. Yes.

  The guide members 85a, 85b, and 85c are plate-like members that are erected on the bottom surface of the case member 81a and are located inside the restricting regions 84a, 84b, and 84c, and their widths are larger than the widths of the restricting regions 84a, 84b, and 84c. It is formed small.

  The paper mounting table 84 moves in the recording paper stacking direction when the lifting arms 82 and 83 are rotated. At this time, since the restricting regions 84a, 84b, and 84c are restricted from moving in the horizontal direction by the guide members 85a, 85b, and 85c, the movement of the paper mounting table 84 is substantially only in the stacking direction of the recording paper. In the example shown in FIG. 2, the shape of the restriction regions 84a, 84b, 84c and the guide members 85a, 85b, 85c is shown as a substantially rectangular shape, but the shape is intended to restrict the movement in the lateral direction. Any shape may be used, and the formation position and number are not limited.

  FIG. 3 is a block diagram illustrating a control unit that controls the rotation of the lifting arms 82 and 83. The paper feed cassette 81 is provided with an inclination setting means 87 for setting the inclination angle of the paper mounting table 84 and arm driving means 88a and 88b as elevating member driving means for rotating the elevating arms 82 and 83.

  The inclination setting unit 87 includes a sheet detection unit 87a, a temperature sensor 87b, a humidity sensor 87c, and a sheet input unit 87d, and is connected to the arm driving units 88a and 88b. The inclination setting means 87 calculates information obtained from these means to set the inclination angle of the paper mounting table 84, and determines the amount of rotation of the elevating arms 82 and 83 based on the set inclination angle. This is a device for sending drive control signals to the arm drive means 88a and 88b. As the tilt setting means 87, arithmetic means such as a CPU (Central Processing Unit) or DSP (digital signal processor) may be used, and an information processing apparatus equipped with a memory, an external storage device, or the like may be used as necessary. .

  The paper detection means 87a detects the state of the paper loaded on the paper placement table 84. Examples of the state of the paper to be detected include the amount of paper loaded, the quality and thickness of the paper, the amount and direction of warping (curling) and bending. As a specific detection method, when detecting the amount of paper, a weight sensor may be provided on the paper mounting table 84. When detecting the quality and thickness of the paper, various contact-type sensors may be brought into contact with the uppermost layer of the paper. Further, when detecting warping or bending of a sheet, a plurality of optical sensors or contact sensors may be used to measure the positions of a plurality of positions on the sheet and measure the deviation from the plane.

  The temperature sensor 87b is a sensor that detects the temperature of the environment in which sheets are stacked, and a commonly used temperature sensor may be used. The position where the temperature sensor 87b is provided is not limited as long as it is inside the paper feed cassette 81. However, the back surface or the front surface of the paper placing table 84, the uppermost surface of the stacked paper, the space above the paper placing table 84, and the like are possible. As close as possible to the paper.

  The humidity sensor 87c is a sensor that detects the humidity of the environment in which the sheets are stacked, and a commonly used humidity sensor may be used. The position where the humidity sensor 87c is provided is not limited as long as it is inside the paper feed cassette 81. However, the back surface or the front surface of the paper placing table 84, the uppermost surface of the stacked paper, the space above the paper placing table 84, and the like are possible. As close as possible to the paper.

  The paper input means 87d is an interface for inputting the state of the paper from the outside, and may be an externally connected input device or a wired or wireless information communication device as long as information can be input from the outside. Good. Examples of the state of the input paper include the amount of stacked paper, the quality and thickness of the paper, and the amount and direction of warping and bending.

  The arm drive means 88 a and 88 b are mechanical drive devices such as a servo motor that is rotationally driven based on a control signal from the inclination setting means 87. The power generated by the arm driving means 88a and 88b is transmitted to the gears 86a and 86b through various power transmission mechanisms as necessary to rotate the elevating arms 82 and 83 and maintain them at a predetermined angle.

  The inclination setting means 87 sets the inclination of the paper placement table 84 based on various information detected or input by the paper detection means 87a, temperature sensor 87b, humidity sensor 87c, and paper input means 87d. As an inclination setting method, it may be set based on various types of information with reference to a preset table, or may be calculated by inputting various types of information into a previously input calculation method. In addition, any one information of the paper detection unit 87a, the temperature sensor 87b, the humidity sensor 87c, and the paper input unit 87d may be used, or information detected or input by a plurality of units may be used.

  Next, the operation of the paper feed cassette 81 which is the paper feed device of this embodiment will be described in detail with reference to FIGS. 4 is a schematic cross-sectional view of a state in which a large amount of recording paper is stacked, and FIG. 5 is a schematic cross-sectional view of a state in which a small amount of recording paper is stacked.

  In a state where a large amount of recording paper is stacked on the paper mounting table 84, the lifting arms 82 and 83 are independent so that the paper mounting table 84 has the inclination set by the inclination setting means 87 as shown in FIG. The sheet mounting table 84 is held in a state close to the bottom surface of the case member 81a. At this time, the uppermost recording sheet (sheet P) is in contact with the pickup roller 11a, and when the pickup roller 11a rotates, the sheet P is conveyed to the sheet feeding side and the sheet feeding roller 11b and the separation roller 11c contact each other. The sheet is conveyed from the front end of the sheet P to the nip region which is a part. When a plurality of recording sheets are pulled out by being overlapped by the pickup roller 11a, each recording sheet is separated one by one by the separation roller 11c when each recording sheet passes between the sheet feeding roller 11b and the separation roller 11c. The multi-feeding is prevented in which the recording sheets are conveyed while being overlapped.

  As shown in FIG. 5, when the recording paper is consumed by using the image forming apparatus 100 and the recording paper on the paper mounting table 84 is loaded in a small amount, the paper mounting table 84 is set by the inclination setting means 87. The elevating arms 82 and 83 are independently rotated so as to be inclined, and the sheet mounting table 84 is held at an upper position away from the bottom surface of the case member 81a. At this time, as in FIG. 4, the upper recording sheet (sheet P) is in contact with the pickup roller 11a, and when the pickup roller 11a rotates, the sheet P is conveyed to the sheet feeding side and separated from the sheet feeding roller 11b. The sheet P is conveyed from the leading end of the sheet P to a nip region that is a contact portion of the roller 11c.

FIG. 6 is a schematic plan view showing a state in which the arm driving means 88 a and 88 b are connected to the paper feed cassette 81. As shown in FIG. 6, gears 86a and 86b attached to the lifting arms 82 and 83 are connected to arm driving means 88a and 88b via additional gears 86c and 86d, respectively. Therefore, when the inclination setting means 87 sets the inclination angle of the paper mounting table 84 and sends a drive control signal to the arm driving means 88a and 88b based on the set inclination angle, the lifting arms 82 and 83 are connected via the gear mechanism. Are rotated independently. As a result, the inclination of the sheet mounting table 84 is set and maintained at an optimum angle for conveying the sheet P. In FIG. 6, the sheet placing table 84 is maintained so as to be parallel to the conveyance direction of the sheet P, and the leading edge of the sheet P is accurately conveyed to the nip region where the sheet feeding roller 11b and the separation roller 11c contact each other. The Therefore, in the paper feeding device of the present embodiment, it is possible to flexibly supply paper according to the type of paper and the change in the state of the paper.
(Second Embodiment)
Next, a second embodiment of the present invention will be described. The description of the configuration common to the first embodiment is omitted. FIG. 7 is a schematic cross-sectional view showing a state in which recording paper is stacked on the paper feed cassette 81 of the second embodiment. As shown in FIG. 7, when the inclination setting means 87 sets an angle that is not substantially horizontal with respect to the bottom surface of the case member 81a as the set inclination angle of the paper mount table 84, the elevating arms 82 and 83 rotate independently of each other. Thus, the sheet mounting table 84 is maintained at the set inclination angle. At this time, as in the first embodiment, the upper recording paper (sheet P) is in contact with the pickup roller 11a, and when the pickup roller 11a rotates, the sheet P is conveyed to the paper feeding side.

In the second embodiment, the inclination angle of the paper mounting table 84 is not horizontal with respect to the bottom surface of the case member 81a. However, there are various types such as the amount of stacked paper detected or input by the paper detection means 87a, temperature sensor 87b, humidity sensor 87c, paper input means 87d, the quality and thickness of the paper, and the amount and direction of warping and bending. Based on the information, the inclination setting means 87 sets the inclination angle of the sheet mounting table 84, so that the leading edge of the sheet P is accurately conveyed to the nip region where the paper feed roller 11b and the separation roller 11c contact each other. Therefore, in the paper feeding device of the present embodiment, it is possible to flexibly supply paper according to the type of paper and the change in the state of the paper.
(Third embodiment)
Next, a third embodiment of the present invention will be described. The description of the configuration common to the first embodiment is omitted. FIG. 8 is a schematic cross-sectional view of a state in which plain paper recording paper is stacked on the paper feed cassette 81. FIG. 9 is a schematic cross-sectional view of a state in which thick recording paper is stacked on the paper feed cassette 81. In the figure, the thickness is emphasized as the sheet P, but the thickness in the figure does not reflect the actual thickness of the recording paper (sheet P).

  In FIGS. 8 and 9, the separating / feeding means including the pickup roller 11a, the sheet feeding roller 11b, and the separating roller 11c is disposed to be inclined with respect to the bottom surface of the case member 81a. An imaginary straight line connecting a nip region where the paper feed roller 11b and the separation roller 11c are in contact with a portion where the pickup roller 11a and the sheet P are in contact is defined as a nip line 11d. Although the example in which the nip line 11d is inclined with respect to the bottom surface of the case member 81a is shown here, it may be horizontal.

  The inclination setting unit 87 determines the type of the recording sheet by inputting the detection result of the sheet detection unit 87a and information about the sheet from the sheet input unit 87d. The tilt setting means 87 sets the tilt angle of the paper mounting table 84 based on the type of recording paper loaded on the paper mounting table 84. Specifically, the paper quality and thickness of the sheet P, which is the uppermost layer of the recording paper, are detected using a contact sensor or the like as the paper detection means 87a. Further, an external input device may be used as the paper input unit 87d, and the user may appropriately input the paper quality and thickness of the recording paper.

  As shown in FIG. 8, when the recording paper loaded on the paper placement table 84 is plain paper, the inclination setting means 87 is larger than the nip line 11d as the inclination angle of the paper placement table 84 with respect to the case member 81a. Set the angle. The tilt setting means 87 sends a drive control signal to the arm drive means 88a and 88b based on the set tilt angle, and the lift arms 82 and 83 are independently rotated and maintained.

  When the sheet P is conveyed from the sheet placing table 84 by the rotation of the pickup roller 11a, the leading end of the sheet P bends downward due to its own weight (the sheet is bent). Therefore, if the inclination angle of the paper mounting table 84 is maintained to be larger than the nip line 11d, even if the sheet P is folded and bent downward as it is conveyed, On the other hand, the leading edge of the sheet P is accurately conveyed.

  As shown in FIG. 9, when the recording paper loaded on the paper mounting table 84 is thick paper, the inclination setting means 87 is an angle along the nip line 11d as an inclination angle of the paper mounting table 84 with respect to the case member 81a. Set. The tilt setting means 87 sends a drive control signal to the arm drive means 88a and 88b based on the set tilt angle, and the lift arms 82 and 83 are independently rotated and maintained.

  In the case of thick and hard paper such as thick paper, even if the sheet P is conveyed from the paper mounting table 84 by the rotation of the pickup roller 11a, the amount of deflection of the front end of the sheet P due to its own weight is small. Therefore, the leading edge of the sheet P is accurately conveyed with respect to the nip region by maintaining the inclination angle of the sheet placing table 84 at an angle similar to that of the nip line 11d.

Therefore, in the paper feeding device according to the present embodiment, it is possible to flexibly supply paper according to the type of paper in consideration of paper folding.
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. The description of the configuration common to the first embodiment is omitted. FIG. 10 is a schematic cross-sectional view of a state in which recording sheets warped upward are stacked on the paper feed cassette 81 according to the fourth embodiment. FIG. 11 is a schematic cross-sectional view of a state in which recording sheets warped downward are stacked on the sheet feeding cassette 81 according to the fourth embodiment.

  The tilt setting means 87 determines the direction and amount of warping (curl) of the recording paper by inputting the detection result of the paper detection means 87a and information on the paper from the paper input means 87d. The tilt setting means 87 sets the tilt angle of the paper mounting table 84 based on the warp (curl) of the recording paper loaded on the paper mounting table 84. Specifically, a plurality of optical position sensors are used as the paper detection means 87a, the positions of the leading end portion and the central portion of the recording paper are detected, and the deviation from the plane on the paper mounting table 84 is calculated, thereby recording paper. Detect the direction and amount of warpage. Further, an external input device may be used as the paper input unit 87d, and the user may appropriately input the direction and amount of warping of the recording paper.

  As shown in FIG. 10, when the recording paper loaded on the paper placement table 84 is warped upward, the inclination setting means 87 raises the elevating arm 82 and lowers the elevating arm 83, and the leading end of the sheet P Is set so that the sheet mounting table 84 is inclined toward the nip region. The tilt setting means 87 sends a drive control signal to the arm drive means 88a and 88b based on the set tilt angle, and the lift arms 82 and 83 are independently rotated and maintained. As a result, when the pickup roller 11a rotates and the leading edge of the sheet P reaches the sheet feeding roller 11b, the warp of the sheet P is offset by the inclination angle of the sheet placing table 84, and the leading edge of the sheet P is moved relative to the nip region. It is conveyed accurately.

  As shown in FIG. 11, when the recording paper loaded on the paper mounting table 84 is warped downward, the tilt setting means 87 lowers the lifting arm 82 and raises the lifting arm 83, and the leading end of the sheet P Is set so that the sheet mounting table 84 is inclined toward the nip region. The tilt setting means 87 sends a drive control signal to the arm drive means 88a and 88b based on the set tilt angle, and the lift arms 82 and 83 are independently rotated and maintained. As a result, when the pickup roller 11a rotates and the leading edge of the sheet P reaches the sheet feeding roller 11b, the warp of the sheet P is offset by the inclination angle of the sheet placing table 84, and the leading edge of the sheet P is moved relative to the nip region. It is conveyed accurately.

Therefore, in the paper feeding device according to the present embodiment, it is possible to flexibly supply paper in consideration of paper warpage (curl).
(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. The description of the configuration common to the first embodiment is omitted. FIG. 12 is a schematic cross-sectional view of a state in which recording paper is stacked on the paper feed cassette 81 according to the fifth embodiment.

  When the recording paper is stored in the paper feed cassette 81 for a long period of time, warping may occur depending on conditions such as environmental temperature, humidity, paper type, and whether or not printing is performed on the back paper. . Therefore, the inclination setting unit 87 acquires the condition in which the recording sheet is stored by inputting the detection result of the sheet detection unit 87a and information regarding the sheet from the sheet input unit 87d.

  Specifically, the temperature sensor 87b and the humidity sensor 87c are used as the paper detection means 87a to detect the temperature and humidity of the environment where the recording paper is stored. Further, in the case of backing paper printing in which the back side of the recording paper once printed on the front side is reused, an external input device is used as the paper input means 87d, and information indicating backing paper printing is inputted as a paper condition. . Further, an external input device may be used as the paper input means 87d, and the user may appropriately input the temperature and humidity stored in the recording paper.

  Inclination setting means 87 obtains the direction and amount of warping occurring on the recording paper based on conditions such as the environmental temperature, humidity, paper type, and whether or not backing paper printing was used. . As a method for obtaining the warp, it may be set based on various types of information with reference to a preset table, or may be calculated by inputting various types of information into a previously input calculation method. Thereafter, the tilt setting means 87 sets the tilt angle of the sheet mounting table 84 based on the obtained warp (curl) of the recording sheet.

  For example, when information indicating that printing on the back paper is input from the paper input unit 87d, the temperature detected by the temperature sensor 87b is 30 ° C., and the humidity detected by the humidity sensor 87c is 80%, the upward direction is applied. It is determined that the warp is large. The tilt setting means 87 raises the lift arm 82 and lowers the lift arm 83, and sets the tilt angle of the sheet mounting table 84 so that the leading end of the sheet P faces the nip region. The tilt setting means 87 sends a drive control signal to the arm drive means 88a and 88b based on the set tilt angle, and the lift arms 82 and 83 are independently rotated and maintained. As a result, when the pickup roller 11a rotates and the leading edge of the sheet P reaches the sheet feeding roller 11b, the warp of the sheet P is offset by the inclination angle of the sheet placing table 84, and the leading edge of the sheet P is moved relative to the nip region. It is conveyed accurately.

  Therefore, in the paper feeding device according to the present embodiment, it is possible to flexibly supply paper in consideration of paper storage status, environmental conditions, paper type, and the like.

DESCRIPTION OF SYMBOLS 11 ... Separation feeding means 11a ... Pick-up roller 11b ... Paper feed roller 11c ... Separation roller 11d ... Nip line 81 ... Paper feed cassette 81a ... Case member 82, 83 ... Elevating arm 82a, 83a ... Plate-shaped part 82b, 83b ... Rotation Shaft portions 82c, 83c ... support portion 84 ... paper mounting table 84a ... restriction area 85a ... guide members 86a-d ... gear 87 ... inclination setting means 87a ... paper detection means 87b ... temperature sensor 87c ... humidity sensor 87d ... paper input means 88a , B... Arm driving means

Claims (6)

A paper mounting table on which paper is placed;
Separation feeding means for separating and feeding the sheets one by one;
A plurality of elevating members for moving the paper mounting table in the paper stacking direction;
A plurality of lifting member driving means for independently driving the plurality of lifting members;
Inclination setting means for setting the inclination of the paper mounting table,
The elevating member includes a flat plate-like portion, a rotary shaft portion provided on the plate-like portion to pivotally support the plate-like portion, and a support for supporting the paper placement table movably in the stacking direction. With
A paper feeding device that controls the inclination of the sheet mounting table by driving the plurality of lifting member driving means based on the inclination set by the inclination setting means. The sheet feeding device according to claim 1,
The sheet feeding device, wherein the rotation shaft portion is positioned at a center side from the support portion in a feeding direction in which the sheet on the sheet placing table is fed. The sheet feeding device according to claim 1 or 2,
The inclination setting means includes a paper detection means for detecting the state of the paper,
The paper feeding device, wherein the inclination is set based on a detection result of the paper detection means. A sheet feeding device according to any one of claims 1 to 3,
The inclination setting means includes a temperature sensor that measures temperature and / or a humidity sensor that measures humidity,
The sheet feeding device, wherein the inclination is set based on a measurement result of the temperature sensor and / or the humidity sensor. The sheet feeding device according to any one of claims 1 to 4,
The inclination setting means includes a paper input means for setting the type of the paper,
The sheet feeding device, wherein the inclination is set based on the type of the sheet input by the sheet input unit. A paper feeding device according to any one of claims 1 to 5,
An image forming apparatus, comprising: an image forming unit that forms an image on a sheet supplied from the sheet feeding device.

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