JP2024075829A - Paper feeder and image forming apparatus - Google Patents

Abstract

[Problem] To provide a paper feeder and an image forming apparatus that can reduce paper feed failures such as paper separation errors (double feed) and pick errors even when different types of paper are fed from the same tray. [Solution] A paper feeder according to one aspect of the present disclosure includes a tray, a feed roller, a paper feed roller, a guide member that guides paper fed from the tray toward the paper feed roller, a lifting mechanism that can change the height of the tray, and a control unit that executes a paper feed process, the control unit having a setting unit that receives job settings including settings related to multiple types of paper including a first paper and a second paper that is thicker than the first paper, and a lifting control unit that controls the lifting mechanism so that when the second paper is set, the height of the tray relative to the guide member is higher by a first predetermined amount before the start of the paper feed process compared to when the first paper is set. [Selected Figure] Figure 10

Description

This disclosure relates to a paper feeder and an image forming device.

Conventionally, image forming devices such as copiers and printers are provided with a paper feeder that feeds paper to an image forming section, an image reading section, etc. The paper feeder includes, for example, a tray on which paper is placed, a lifting mechanism that raises and lowers the tray, and a paper feed unit that separates and feeds the paper placed on the tray one by one.

For example, Patent Document 1 discloses a printer equipped with a paper feed roller as a paper feed unit. In the printer described in Patent Document 1, the tray is raised and the recording paper is pressed against the paper feed roller, and the paper feed roller is rotated to separate and feed the recording paper one sheet at a time.

The printer described in Patent Document 1 is provided with a first paper tray capable of storing recording paper made of thick paper such as postcards, and a second paper tray capable of storing recording paper made of thin paper such as copy paper that is thinner than postcards.

In addition to the above-mentioned paper feed unit, the paper feed unit may also have, for example, a feed roller that feeds the topmost paper placed on the tray, a feed roller that feeds the fed paper to the transport path, and a guide member that guides the paper fed by the feed roller toward the feed roller. Generally, the guide member is made of a rubber material with a high coefficient of friction. This provides resistance to the fed paper, thereby preventing paper separation errors (double feed).

JP 2001-097567 A

However, in a paper feeder such as the one described above, when multiple types of paper are fed, a tray is required for each type of paper, which can lead to an increase in the size of the device. In addition, when a paper feeder such as the one described above is configured to feed different types of paper from the same tray, the following problems arise. For example, when the type of paper is plain paper, the guide member provides resistance to the plain paper being fed, so the plain paper can be fed toward the paper feed roller while preventing paper separation errors (double feed). However, when the type of paper is stiff paper such as cardboard, the guide member provides a large resistance to the cardboard being fed, which can increase slippage of the feed roller and cause pick errors.

Therefore, one aspect of the present disclosure aims to provide a paper feeder and an image forming apparatus that can reduce paper feed problems such as paper separation errors (double feeds) and pick errors, even when feeding different types of paper from the same tray, for example.

A paper feed device according to one aspect of the present disclosure includes a tray on which paper can be placed, a feed roller that feeds the paper placed on the tray, a feed roller that feeds the fed paper to a transport path, a guide member that guides the paper fed from the tray toward the feed roller and is inclined upward as it approaches the feed roller, a lifting mechanism that can change the height of the tray, and a control unit that executes a paper feed process that feeds the paper fed from the tray to the transport path by rotating the feed roller, and the control unit has a setting unit that accepts job settings including settings for multiple types of paper including a first paper and a second paper that is thicker than the first paper, and a lifting control unit that controls the lifting mechanism so that when the second paper is set, the height of the tray relative to the guide member is higher by a first predetermined amount before the start of the paper feed process compared to when the first paper is set.

FIG. 1 is a schematic cross-sectional view showing an image forming apparatus. FIG. FIG. 4 is a cross-sectional view of the document transport section showing the lifting mechanism. FIG. FIG. 11 is a schematic side view of the paper feed unit in a state where the upper limit sensor does not detect the detection piece. FIG. 11 is a schematic side view of the paper feed unit in a state where the upper limit sensor detects the detection piece. FIG. FIG. 2 is a block diagram showing a hardware configuration of the image forming apparatus. 13 is a screen for accepting operational input related to a plurality of types of paper, which is displayed on an operation panel. 4 is a cross-sectional view of the document transport section showing the initial position of the left tray. FIG. 4 is a cross-sectional view of the document transport section showing the height position of the left tray in the plain paper mode. FIG. 11 is a cross-sectional view of the document transport section showing the height position of the left tray in the thick paper mode. FIG. 11 is a schematic side view of the document transport section comparing the height position of the left tray in the plain paper mode and the height position of the left tray in the thick paper mode. FIG. 13 is an example of a flow relating to lift control by a control unit before starting a paper feeding process. 13 is an example of a flow relating to elevation correction control during a paper feed process by a control unit. 13 is an example of a flow relating to lift correction control when a pick miss is determined by a control unit. 13 is an example of a flow according to a first modified example of elevation correction control during a paper feed process by the control unit.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that in the drawings, identical or equivalent elements are given the same reference numerals, and duplicate descriptions will be omitted.

Below, an image forming apparatus 1 according to one aspect of the present disclosure will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing the image forming apparatus 1. In the following description, the printing unit 10 (paper feed unit 110) side is defined as the lower side, the document transport unit 30 side as the upper side, the discharge tray 360 side of the document transport unit 30 as the right side, and the transport path 330 side of the document transport unit 30 as the left side.

The image forming device 1 is, for example, a multifunction device having a copying function, a printer function, a scanner function, and a facsimile function. The image forming device 1 transmits image data read by the image reading unit 20 to the outside, and also forms an image on the document in monochrome or multiple colors using the image data of the read document or image data received from the outside.

The image forming device 1 includes a printing unit 10, an image reading unit 20, an original transport unit 30, and an operation panel 40 (see FIG. 7). The printing unit 10 forms an image on a recording medium such as paper. The image reading unit 20 is disposed above the printing unit 10 and reads originals. The original transport unit 30 is disposed above the image reading unit 20 and transports originals placed on a tray sequentially toward the original placement table of the image reading unit 20.

The printing unit 10 will be described below using Figure 1.

The printing unit 10 includes a paper feed unit 110, a pair of transport rollers 120, a pair of registration rollers 130, an image forming unit 140, a pair of discharge rollers 150, and a discharge tray 160. Inside the image forming device 1, a transport path R1 is formed for sending paper fed from the paper feed unit 110 to the discharge tray 160 via the pair of transport rollers 120, the pair of registration rollers 130, the image forming unit 140, and the pair of discharge rollers 150.

The paper feed unit 110 includes a cassette 111 arranged below the image forming unit 140, a paper feed tray 112 on which paper is stacked, a pickup roller 113 provided above one end of the paper feed tray 112, a paper feed roller 114 arranged downstream of the pickup roller 113 in the paper transport direction, and a separation roller 115 pressed against the paper feed roller 114.

In the paper feed section 110, the pickup roller 113 picks up paper from the paper feed tray 112 and guides it to the paper feed roller 114. The paper passes between the paper feed roller 114 and the separation roller 115 to separate it into individual sheets, and the paper is transported to the transport path R1 by the transport roller pair 120.

The pair of registration rollers 130 feeds the paper in accordance with the timing of the toner image formation. The pair of registration rollers 130 temporarily stops the paper, aligns the leading edge of the paper, and then transports the paper in accordance with the timing of the transfer of the toner image in the nip area between the intermediate transfer belt 146a and the transfer roller 147 described below.

The image forming unit 140 includes a photoconductor drum 141, a charger 142, an exposure unit 143, a development unit 144, a cleaner unit 145, an intermediate transfer belt unit 146, a transfer roller 147, and a fixing unit 148.

The image data handled by the image forming unit 140 corresponds to color images in four colors: black (K), cyan (C), magenta (M), and yellow (Y). For this reason, four photoconductor drums 141, chargers 142, developing units 144, and cleaner units 145 are provided so as to form four types of latent images corresponding to each color, and these constitute four image forming stations. Four toner cartridges are provided so as to supply the corresponding toner to each image forming station.

The photoconductor drum 141 is an electrostatic latent image carrier in which a photosensitive layer is formed on the surface of a cylindrical conductive base body. The charger 142 charges the surface of the photoconductor drum 141 to a predetermined potential. The exposure unit 143 is a laser scanning unit equipped with a laser emission unit, a reflecting mirror, etc. The exposure unit 143 exposes the charged surface of the photoconductor drum 141 to light, thereby forming an electrostatic latent image on the surface of the photoconductor drum 141 according to image data. The development unit 144 visualizes the electrostatic latent image formed on the surface of the photoconductor drum 141 with four color toners. The cleaner unit 145 removes and collects toner remaining on the surface of the photoconductor drum 141 after development and image transfer.

The intermediate transfer belt unit 146 includes an intermediate transfer belt 146a, a drive roller 146b, a driven roller 146c, and four intermediate transfer rollers 146d. The intermediate transfer belt unit 146 is disposed above the photosensitive drums 141. The intermediate transfer belt 146a is provided so as to contact each photosensitive drum 141, and a toner image is formed on the intermediate transfer belt 146a by sequentially superimposing and transferring the toner images of each color formed on the corresponding photosensitive drum 141 to the intermediate transfer belt 146a using each intermediate transfer roller 146d.

The transfer roller 147 is disposed near the drive roller 146b on the transport path R1. When the paper passes through the nip area between the transfer roller 147 and the intermediate transfer belt 146a, the toner image formed on the intermediate transfer belt 146a is transferred to the paper.

The fixing unit 148 includes a heat roller 148a and a pressure roller 148b. The fixing unit 148 is disposed above the transfer roller 147 on the transport path R1, in other words, downstream in the transport direction of the paper. When the paper passes through the nip area between the heat roller 148a and the pressure roller 148b, the toner image transferred to the paper is melted, mixed, and pressed against the paper, and the toner image is thermally fixed to the paper. The paper with the fixed toner image is transported to the discharge tray 160 by the pair of discharge rollers 150.

When an image is to be formed on the back side of the paper in addition to the front side, the paper is transported in the opposite direction from the discharge roller pair 150 to the inversion path R2. In the inversion path R2, the paper is inverted by the inversion roller pair 170 and guided again to the registration roller pair 130. After that, the paper, on whose back side an image has been formed in the same manner as on the front side, is transported to the discharge tray 160.

Next, the image reading unit 20 will be described using FIG. 1.

The image reading unit 20 reads an image formed on a sheet of paper and generates image data. A transparent plate-shaped contact glass 21 for feeding and reading is provided on the left side of the top surface of the image reading unit 20. A transparent plate-shaped contact glass 22 for placed reading is provided on the top surface of the image reading unit 20 and to the right of the contact glass 21 for feeding and reading. A document transport unit 30 is attached above the image reading unit 20 via a hinge or the like so as to be freely opened and closed. When the document transport unit 30 is opened via a hinge or the like, the top surface of the image reading unit 20 is opened and a document can be manually placed on the contact glass 22 for placed reading. An operation panel 40 is provided to the left of the top surface of the image reading unit 20. The operation panel 40 includes a display panel, a touch panel, hard keys, etc.

The image reading unit 20 further includes a light source, multiple mirrors, an imaging lens, and a line sensor. The image reading unit 20 exposes the paper surface to the light source, and guides the light reflected from the paper surface to the imaging lens using multiple mirrors. The imaging lens then focuses the reflected light on the light receiving element of the line sensor. The line sensor detects the luminance and chromaticity of the reflected light focused on the light receiving element, and generates image data based on the image of the paper surface. A CCD, CIS, or the like is used as the line sensor.

Next, the document transport unit 30 will be described with reference to Figs. 1 to 3. Fig. 2 is a perspective view showing the document transport unit 30. Fig. 3 is a cross-sectional view showing the document transport unit 30. The document transport unit 30 transports the document placed on the paper feed tray 310 (described later) toward the feed/read contact glass 21. The document transport unit 30 functions as a cover that holds the document from above.

2 and 3, the document transport unit 30 has a main body 31 having various structures. The main body 31 includes a paper feed tray 310 on which paper can be placed, a paper feed unit 320 that feeds paper from the paper feed tray 310, a transport path 330 that transports the fed paper, a plurality of transport roller pairs 340 that transport paper to the transport path 330, a discharge roller pair 350, a discharge tray 360, and a lifting mechanism 370 (see FIG. 4) that raises and lowers the paper feed tray 310.

The paper feed tray 310 has a shape that allows multiple original documents to be stacked and placed on it. The original documents placed on the paper feed tray 310 are sent one by one to the transport path 330 by the paper feed unit 320.

The paper feed tray 310 is arranged vertically next to the discharge tray 360. Specifically, the paper feed tray 310 is arranged on the upper level, and the discharge tray 360 is arranged on the lower level.

The paper feed tray 310 includes a left tray 311 and a right tray 312. The left tray 311 and the right tray 312 are arranged side by side in the left-right direction. The left tray 311 can be raised and lowered by a lifting mechanism 370. The left tray 311 can be rotated in the up-down direction around a pivot point F located at the right end. The specific configuration of the lifting mechanism 370 will be described later.

The right tray 312 is fixed to the main body 31. The right tray 312 is inclined so that it becomes lower from the right side to the left side. In other words, the inclination is provided so that when a document is placed on the right tray 312, the document slides toward the left tray 311 under its own weight. Note that, although only the left tray 311 of the paper feed tray 310 can be raised and lowered, this is not limiting, and the left tray 311 and right tray 312 may be raised and lowered as a whole.

The left tray 311 is provided with two document guides 311a for aligning the widthwise (front-to-back) edges of the document. The two document guides 311a are provided facing each other in the widthwise direction on the left tray 311 so that they can move in the widthwise direction. This allows the document to be sandwiched between the two document guides 311a and the two document guides 311a to be moved to positions where they contact both ends of the document in the widthwise direction, thereby positioning the document in the widthwise direction.

As shown in FIG. 3, the main body 31 is provided with a wall surface 31a that faces the left end (tip) of the left tray 311 and rises upward. The wall surface 31a has a curved shape that follows the rotation trajectory of the left tray 311. The tip of the document can be abutted against the wall surface 31a to position the document in the transport direction.

A cover 31b is attached to the top surface of the main body 31 so as to be freely opened and closed relative to the main body 31. A grip 31c is provided on the cover 31b for opening and closing the cover 31b relative to the main body 31. When the user grips the grip 31c, the locked state between the main body 31 and the cover 31b is released, and the cover 31b can be moved in the direction of opening.

In addition, a storage section 31d is provided at the rear inside the main body 31 to store various drive sources and power transmission members. The storage section 31d stores, for example, a paper feed motor 322b (see FIG. 7) and a lift motor 371 (see FIG. 7) constituting a lift mechanism 370 (described below) as drive sources, and gears constituting a lift mechanism 370 (described below) as power transmission members.

The lifting mechanism 370 that raises and lowers the left tray 311 will be described with reference to FIG. 4. FIG. 4 is a cross-sectional view of the document transport unit 30 showing the lifting mechanism 370. In FIG. 4, components other than the lifting mechanism 370, the paper feed tray 310, the paper feed unit 320, etc. are not shown.

The lifting mechanism 370 includes a lifting motor 371, a first gear 372 that meshes with the output shaft of the lifting motor 371, a second gear 373 that meshes with the first gear 372, a third gear 374 that meshes with the second gear 373, a sector gear 375 that meshes with the third gear 374, a rotating shaft 376 that is fixed to the center of rotation of the sector gear 375 and extends in the front-to-rear direction, and a pair of arms 377 that extend leftward from the rotating shaft 376 and support the left portion of the left tray 311 from below.

In the above configuration, when the lift motor 371 is driven, the driving force of the lift motor 371 is transmitted to the sector gear 375 via the first gear 372, the second gear 373, and the third gear 374, causing the sector gear 375 to rotate. As the sector gear 375 rotates, the pair of arms 377 rotates up and down together with the rotation shaft 376. For example, when the left ends of the pair of arms 377 are rotated upward, the left end of the left tray 311 rotates upward around the pivot F, and the left tray 311 rises. When the left ends of the pair of arms 377 are rotated downward, the left end of the left tray 311 rotates downward around the pivot F, and the left tray 311 descends.

The paper feed unit 320 will be described with reference to Figures 5 and 6. Figure 5 is a perspective view showing the paper feed unit 320. Some components of the paper feed unit 320 are not shown in Figure 5. Figure 6A is a schematic side view of the paper feed unit 320 in a state where the upper limit sensor 32 described below does not detect the detection piece 325d. Figure 6B is a schematic side view of the paper feed unit 320 in a state where the upper limit sensor 32 described below detects the detection piece 325d.

As shown in Figures 5 and 6, the paper feed unit 320 mainly includes a pickup roller 321, a paper feed roller 322, a cover member 323 that covers the pickup roller 321 and the paper feed roller 322 together, a separation roller 324, a pressure arm 325 that presses the cover member 323 from above, and a guide member 326 that guides the paper fed from the pickup roller 321 toward the paper feed roller 322.

The pickup roller 321 picks up paper from the left tray 311. The pickup roller 321 is provided with a rotating shaft 321a that extends in the front-rear direction. The rotating shaft 321a is rotatably supported by a cover member 323.

The paper feed roller 322 feeds the paper fed by the pickup roller 321 to the transport path 330. The paper feed roller 322 is disposed downstream (left side) of the pickup roller 321 in the transport direction. The paper feed roller 322 is provided with a rotating shaft 322a extending in the front-rear direction. The rotating shaft 322a penetrates the cover member 323 and is rotatably supported by the main body 31. A paper feed motor 322b (see FIG. 7) is connected to one end of the rotating shaft 322a. The rotating shaft 322a and the paper feed roller 322 are connected via a paper feed clutch 322c (see FIG. 7), and the rotating shaft 322a does not rotate even if the paper feed roller 322 rotates while the drive of the paper feed motor 322b is stopped.

The cover member 323 covers the pickup roller 321 and the paper feed roller 322 from above. The bottom of the cover member 323 is open, exposing the bottom of the pickup roller 321 and the bottom of the paper feed roller 322. Inside the cover member 323, the pickup roller 321 and the paper feed roller 322 are connected via a belt, and when the paper feed motor 322b is driven, the pickup roller 321 rotates together with the paper feed roller 322, allowing the topmost sheet of paper on the left tray 311 to be fed in the transport direction.

The cover member 323 is configured so that the right side (the pickup roller 321 side) can swing up and down around the rotation shaft 322a of the paper feed roller 322. The upper and lower limits of the swing range of the cover member 323 are regulated by various regulating members provided on the main body 31.

The separation roller 324 is disposed opposite the paper feed roller 322 and is pressed against the paper feed roller 322. The separation roller 324 applies a conveying force to the paper in the opposite direction to that of the paper feed roller 322.

The pressing arm 325 presses the swing end (right end) of the cover member 323 from above. That is, the pressing arm 325 presses the pickup roller 321 from above via the cover member 323. The pressing arm 325 has a pair of extensions 325a facing each other in the front and rear, a pressing portion 325b that connects the right ends of the pair of extensions 325a, and a pressing member 325c (see FIG. 6A) that presses the pressing portion 325b downward.

The pair of extension parts 325a are provided on the main body part 31 so as to sandwich the pickup roller 321 between them. The pair of extension parts 325a are configured so that the right side can swing up and down with the left end part as a fulcrum. The pressing part 325b is located above the swing end part (right end part) of the cover member 323. The biasing member 325c is provided on one of the pair of extension parts 325a, and biases the right end part of the extension part 325a downward. In other words, the biasing member 325c biases the pressing part 325b downward.

The main body 31 is provided with an upper limit sensor 32 that detects the upper limit position when the left tray 311 is raised. The upper limit sensor 32 is, for example, an optical sensor that irradiates light from a light emitting section 32a toward a light receiving section 32b and detects an object based on whether the light reaches the light receiving section 32b. The upper limit sensor 32 detects the upper limit position of the left tray 311 by detecting a detection piece 325d provided on a pressing arm 325 described below. The upper limit position here refers to the upper limit position of the left tray 311 when a first paper sheet (plain paper) having a reference thickness described below is used.

The pressing arm 325 has a pair of extensions 325a, and the other extension 325a is provided with a detection piece 325d. The detection piece 325d is provided so as to protrude outward in the front-rear direction from the other extension 325a.

Below, the detection of the detection piece 325d by the upper limit sensor 32 is explained using Figure 6.

In the state shown in FIG. 6A, the left tray 311 is not in contact with the pickup roller 321, and the pressing arm 325 presses the pickup roller 321 from above due to the biasing force of the biasing member 325c. In this state, the detection piece 325d of the pressing arm 325 is located below the upper limit sensor 32. In other words, the upper limit sensor 32 is not detecting the detection piece 325d. When the left tray 311 is raised from the state shown in FIG. 6A, the top sheet of the paper stack M in the left tray 311 comes into contact with the pickup roller 321 and pushes up the pressing arm 325 together with the pickup roller 321 against the biasing force of the biasing member 325c. As a result, the detection piece 325d moves upward, resulting in the state shown in FIG. 6B in which the upper limit sensor 32 detects the detection piece 325d. When using the first paper (plain paper) described below, when the upper limit sensor 32 detects the detection piece 325d, the lifting of the left tray 311 is stopped and the paper feeding process described below is started.

As shown in FIG. 6, the guide member 326 guides the paper fed from the left tray 311 toward the paper feed roller 322. The guide member 326 is provided between the pickup roller 321 and the paper feed roller 322. Specifically, the guide member 326 is provided, for example, at the upper end of the wall surface 31a of the main body 31, and is provided so as to incline upward as it approaches the paper feed roller 322. The left end of the guide member 326 is inclined upward so as to approach the nip area between the paper feed roller 322 and the separation roller 324.

The guide member 326 is, for example, a flat plate-shaped member. The upper surface of the guide member 326 is provided with an upwardly inclined guide surface 326a. The guide member 326 is formed of an elastic member made of a rubber-like material with a high coefficient of friction (for example, 1.2 to 1.7), such as silicone or urethane.

In the above configuration, when the topmost sheet of paper on the left tray 311 is fed by the pickup roller 321, the leading edge of the topmost sheet of paper abuts against the guide surface 326a of the guide member 326, and is guided along the guide surface 326a to the feed roller 322. In addition, since the guide member 326 is made of a rubber material with a high coefficient of friction, the guide member 326 acts as a resistance against the paper being fed toward the feed roller 322, effectively preventing paper separation errors (double feed).

The main body 31 is provided with a lower limit sensor 33 (see FIG. 3) that detects the lower limit position of the left tray 311 when it is lowered. The lower limit sensor 33 is, for example, an optical sensor. The lower limit sensor 33 has a similar configuration to the upper limit sensor 32, so a detailed description is omitted. The lower limit sensor 33 also detects the lower limit position of the left tray 311 by detecting a detection piece (not shown) provided on the left tray 311. The lower limit position here is the initial position P1 of the left tray 311, which will be described later.

The main body 31 is provided with an original detection sensor 34 (see FIG. 3) that detects that an original is placed on the left tray 311. The original detection sensor 34 is, for example, an optical sensor having a light-emitting portion and a light-receiving portion. The original detection sensor 34 is provided, for example, in the upper portion of the main body 31, specifically, in a portion facing the front end portion of the left tray 311. When no original is placed on the left tray 311, for example, the light from the light-emitting portion to the light-receiving portion of the original detection sensor 34 is blocked.

The main body 31 is provided with a paper passage sensor 35 (see FIG. 3) that detects paper fed by the paper feed unit 320. The paper passage sensor 35 is, for example, an optical sensor having a light-emitting portion and a light-receiving portion. The paper passage sensor 35 is disposed downstream of the paper feed unit 320 in the transport direction. The paper passage sensor 35 detects that paper has been fed to the transport path 330 by the paper feed unit 320 by detecting the leading edge of the paper transported to the transport path 330 via the paper feed unit 320.

In the above configuration, when the left tray 311 is raised by the lift mechanism 370, the top sheet of paper placed on the left tray 311 comes into contact with the pickup roller 321. Then, when the paper feed motor 322b is driven while the top sheet of paper placed on the left tray 311 is in contact with the pickup roller 321, the top sheet of paper on the left tray 311 is fed to the left by the pickup roller 321. The leading edge of the paper fed to the left by the pickup roller 321 is fed to the paper feed roller 322 via the guide member 326. The paper fed to the paper feed roller 322 via the guide member 326 is fed to the conveying path 330 through the nip area between the paper feed roller 322 and the separation roller 324. The paper conveyed to the conveying path 330 passes through the feed reading contact glass 21 of the image reading unit 20 by a plurality of conveying roller pairs 340, and is then discharged to the discharge tray 360 by the discharge roller pair 350.

The hardware configuration of the image forming device 1 will be described using FIG. 7. FIG. 7 is a block diagram showing the hardware configuration of the image forming device 1.

The image forming device 1 includes a control unit 200, a memory unit 210, a communication unit 220, a printing unit 10, an image reading unit 20, a document transport unit 30, an operation panel 40, etc.

The control unit 200 controls the image forming device 1. The control unit 200 realizes various functions by reading and executing various programs stored in the storage unit 210. The control unit 200 is configured, for example, with one or more CPUs (Central Processing Units), etc.

The storage unit 210 stores various programs and data necessary for the operation of the image forming device 1. The storage unit 210 is configured with a storage device such as a solid state drive (SSD) or a hard disk drive (HDD), which is a semiconductor memory.

The communication unit 220 controls, for example, wireless communication of various data between an external terminal such as a computer. Note that the communication unit 220 is not limited to controlling wireless communication, and may also control wired communication.

The control unit 200 is connected to the memory unit 210, the communication unit 220, the printing unit 10, the image reading unit 20, the paper feed motor 322b, the paper feed clutch 322c, the lifting motor 371, the upper limit sensor 32, the lower limit sensor 33, the document detection sensor 34, the paper passage sensor 35, etc., which constitute the document transport unit 30.

The control unit 200 controls the paper feed motor 322b to rotate the pickup roller 321 and the paper feed roller 322, thereby performing a paper feed process in which paper fed from the left tray 311 is fed to the transport path 330.

The control unit 200 includes a setting unit 201, a lift control unit 202, a determination unit 203, and a counting unit 204.

The setting unit 201 performs settings related to various jobs according to operation input received by the operation panel 40. The various jobs are print jobs, image reading jobs, etc. The setting unit 201 can perform settings related to multiple types of paper for an image reading job, for example. The setting unit 201 can set, as multiple types of paper, for example, a first paper (plain paper), a second paper (thick paper), a third paper (thin paper), and a fourth paper (thick paper for business cards).

The first paper is plain paper with a standard thickness. The second paper is cardboard that is thicker than plain paper. The third paper is thin paper that is thinner than plain paper. The fourth paper is cardboard for business cards that is thicker than plain paper and smaller in size than plain paper.

Note that the setting unit 201 performs settings related to multiple types of paper for an image reading job, but is not limited to this, and may also perform settings related to multiple types of paper for a print job.

The screen for accepting operation inputs related to multiple types of paper will be described using FIG. 8. FIG. 8 shows the screen for accepting operation inputs related to multiple types of paper that is displayed on the operation panel 40.

As shown in FIG. 8, the reception screen displays the text "Please select the type of manuscript," along with a button 41 corresponding to "plain paper," a button 42 corresponding to "thick paper," a button 43 corresponding to "thin paper," and a button 44 corresponding to "business card." When the user touches the desired button, the setting unit 201 sets the type of paper corresponding to that button.

For example, when button 41 corresponding to "plain paper" is touched, setting unit 201 sets plain paper mode. When button 42 corresponding to "thick paper" is touched, setting unit 201 sets thick paper mode. When button 43 corresponding to "thin paper" is touched, setting unit 201 sets thin paper mode. When button 44 corresponding to "business card" is touched, setting unit 201 sets business card mode.

The lift control unit 202 controls the lift motor 371 based on the detection results of the various sensors. The following describes the lift control unit 202's lift control of the left tray 311 before the start of the paper feed process.

9 and 10, the lifting and lowering control of the left tray 311 before the start of the paper feed process will be described. FIG. 9A is a cross-sectional view of the document transport unit 30 showing the initial position P1 of the left tray 311. FIG. 9B is a cross-sectional view of the document transport unit 30 showing the height position P2 of the left tray 311 in the plain paper mode. FIG. 9C is a cross-sectional view of the document transport unit 30 showing the height position P3 of the left tray 311 in the thick paper mode. FIG. 10 is a schematic side view of the document transport unit 30 comparing the height position P2 of the left tray 311 in the plain paper mode with the height position P3 of the left tray 311 in the thick paper mode. In FIGS. 9A, 9B, 9C, and 10, the illustrations of members other than the paper feed tray 310 and the paper feed unit 320 of the document transport unit 30 are omitted.

As shown in FIG. 9A, before the start of the paper feeding process, the left tray 311 is located at the initial position P1.

First, the lift control of the left tray 311 in the plain paper mode will be described with reference to Figures 9B and 10. As shown in Figure 9B, in the plain paper mode, the lift control unit 202 controls the lift motor 371 to lift the left tray 311 from the initial position P1 to a height position P2 at which the upper limit sensor 32 detects the detection piece 325d.

The height position P2 at which the upper limit sensor 32 detects the detection piece 325d is a height position set based on the first paper (plain paper) having a reference thickness. The height position P2 is, for example, a height position at which the leading edge of the paper abuts below the center of the guide surface 326a of the guide member 326 when the topmost paper is fed out by the pickup roller 321 from the paper stack M placed on the left tray 311 after the paper feed process is started. This ensures that the topmost paper fed out has a sufficient distance to run up the guide surface 326a. Therefore, the guide member 326 can guide the paper toward the paper feed roller 322 while suppressing double feeds. Note that height position P2 is the height position where the leading edge of the topmost sheet of paper that has been fed out abuts below the center of guide surface 326a, but it is not limited to this, and as long as there is a sufficient distance for the leading edge of the topmost sheet of paper to run up guide surface 326a, it may be a height position where it abuts near the center of guide surface 326a, or a height position where it abuts above the center of guide surface 326a.

Next, the lift control of the left tray 311 in the thick paper mode will be described with reference to Figures 9C and 10. As shown in Figures 9C and 10, the lift control unit 202 controls the lift motor 371 to raise the left tray 311 by a first predetermined amount A1 compared to the plain paper mode. Specifically, the lift control unit 202 controls the lift motor 371 to raise the left tray 311 from the initial position P1 to a height position P3 that is higher by the first predetermined amount A1 than the height position P2 at which the upper limit sensor 32 detects the detection piece 325d.

The first predetermined amount A1 is set within a range in which the leading edge of the paper can contact the guide surface 326a of the guide member 326 when the topmost paper is fed out by the pickup roller 321 from the paper stack M placed on the left tray 311. In this example, the first predetermined amount A1 is, for example, 3 mm. In this example, the height position P3 is, for example, a height position at which the leading edge of the paper contacts the upper side of the guide surface 326a of the guide member 326 when the topmost paper is fed out by the pickup roller 321 after the paper feed process is started. Note that the height position P3 is a height position at which the leading edge of the fed-out topmost paper contacts the upper side of the guide surface 326a, but is not limited to this, and may be a height position at which the leading edge contacts the vicinity of the center of the guide surface 326a, or a height position at which the leading edge contacts the lower side of the center of the guide surface 326a, as long as it is higher than the height position P2.

The second paper (cardboard) is thicker than the first paper (plain paper), and therefore has greater resistance when a bending force is applied to the paper. Therefore, if the distance traveled by the topmost paper that is fed out on the guide surface 326a is the same as that of the first paper (plain paper), the increased slippage of the pickup roller 321 makes it more likely that a pick-up error will occur.

Therefore, in the thick paper mode, the lift control unit 202 controls the lift motor 371 so that the height is higher by a first predetermined amount A1 compared to the plain paper mode. This reduces the distance that the topmost paper sheet fed by the pickup roller 321 runs up the guide surface 326a. Therefore, the paper can be guided toward the paper feed roller 322 while reducing pick errors. Note that the second paper sheet (thick paper sheet) is thicker than the first paper sheet (plain paper sheet) and the sheets are more likely to separate from each other, making double feeds less likely to occur. Therefore, in the thick paper mode, even if the distance that the paper sheet runs up the guide surface 326a is reduced, double feeds can be reduced.

The following describes the lifting and lowering control of the left tray 311 before the start of the paper feeding process in thin paper mode and business card mode.

In the thin paper mode, the lift control unit 202 controls the lift motor 371 to be higher by a second predetermined amount A2 compared to the plain paper mode. Specifically, the lift control unit 202 controls the lift motor 371 to raise the left tray 311 from the initial position P1 to a height position that is higher by the second predetermined amount A2 than the height position P2 at which the upper limit sensor 32 detects the detection piece 325d.

The second predetermined amount A2 is a value smaller than the first predetermined amount A1. In other words, in thin paper mode, the left tray 311 is raised to a position higher than in plain paper mode and lower than in thick paper mode.

The third paper (thin paper) is thinner than the first paper (plain paper), and therefore has less resistance when a bending force is applied to the paper. Therefore, if the distance that the topmost paper that is fed out runs up the guide surface 326a is the same as the distance that the first paper (plain paper) travels, resistance is applied to the third paper (thin paper), and damage such as bending the leading edge of the paper may occur.

The lift control unit 202 therefore controls the lift motor 371 in the thin paper mode so that it is higher by a second predetermined amount A2, which is smaller than the first predetermined amount A1, compared to the plain paper mode. This makes it possible to reduce the distance that the topmost sheet of paper fed by the pickup roller 321 runs up the guide surface 326a while still maintaining a certain degree of distance. Therefore, the paper can be guided toward the paper feed roller 322 while preventing damage to the paper and double feeds.

In the business card mode, the lift control unit 202 controls the lift motor 371 to be higher by a third predetermined amount A3 compared to the plain paper mode. Specifically, the lift control unit 202 controls the lift motor 371 to raise the left tray 311 from the initial position P1 to a height position that is higher by the third predetermined amount A3 than the height position P2 at which the upper limit sensor 32 detects the detection piece 325d.

The third predetermined amount A3 is a value greater than the first predetermined amount A1. In other words, in business card mode, the left tray 311 is raised to a higher position than in thick paper mode.

The fourth sheet (cardboard for business cards) is thicker and smaller than the first sheet (plain paper), and therefore has greater resistance when a bending force is applied to the paper. Therefore, if the distance that the topmost sheet of paper that is fed out runs up the guide surface 326a is the same as the distance that the first sheet of paper (plain paper) travels, the increased slippage of the pickup roller 321 makes it more likely that a pick-up error will occur.

The lift control unit 202 controls the lift motor 371 so that in the business card mode, the lift motor 371 is higher by a third predetermined amount A3, which is greater than the first predetermined amount A1, compared to the plain paper mode. This reduces the distance that the topmost paper fed by the pickup roller 321 runs up the guide surface 326a. Therefore, the paper can be guided toward the paper feed roller 322 while reducing pick errors. Note that the fourth paper (cardboard for business cards) is thicker than the first paper (plain paper) and the papers are more likely to separate from each other, making double feed less likely to occur. Therefore, in the business card mode, even if the distance that the paper runs up the guide surface 326a is reduced, double feed can be reduced.

Also, as shown in FIG. 10, the lift control unit 202 controls the lift mechanism 370 so that the angle of the loading surface on which the paper of the left tray 311 is loaded with respect to the guide surface 326a is smaller in the thick paper mode than in the plain paper mode. The angle a2 of the loading surface with respect to the guide surface 326a in the thick paper mode is smaller so as to approach the guide surface 326a than the angle a1 of the loading surface with respect to the guide surface 326a in the plain paper mode. Also, as shown in FIG. 10, the pivot point F is provided at the end (right end) of the left tray 311 on the upstream side in the conveying direction. The left tray 311 can be rotated in the vertical direction around the pivot point F located at the right end. For example, the left end of the left tray 311 is rotated upward around the pivot point F to raise the left tray 311. Also, the left end of the left tray 311 is rotated downward around the pivot point F to lower the left tray 311.

As described above, in the thick paper mode, the left tray 311 is raised so that its inclination approaches the guide surface 326a, compared to the plain paper mode. This reduces the resistance when the leading edge of the paper on the left tray 311 contacts the guide surface 326a, thereby reducing the occurrence of pick errors.

The inclination of the left tray 311 is configured so that the higher the left tray 311 is raised, the closer it is to the guide surface 326a. Therefore, in any of the cardboard mode, thin paper mode, and business card mode, the inclination of the left tray 311 is closer to the guide surface 326a than in the plain paper mode, which reduces the occurrence of pick errors.

As described above, by changing the height of the left tray 311 depending on the type of paper, it is possible to reduce paper feeding problems that may occur depending on the type of paper during paper feeding processing.

In addition, the amount by which the left tray 311 is raised after the upper limit sensor 32 detects the detection piece 325d in the lift control unit 202 is determined by storing in advance in the memory unit 210 the rotation angle by which the lift motor 371 is rotated for each type of paper.

In addition, in the thick paper mode, the lift control unit 202 may raise the left tray 311 stepwise from the initial position P1 to the height position P3, or may raise the left tray 311 continuously from the initial position P1 to the height position P3.

First, a case where the left tray 311 is raised in stages from the initial position P1 to the height position P3 will be described. When the document detection sensor 34 detects that a document has been placed on the left tray 311 and any operation input (touch operation input) is received via the operation panel 40, the lift control unit 202 raises the left tray 311 from the initial position P1 to the height position P2 and then stops the left tray 311. This allows the left tray 311 to be raised to the height position P2 in advance before starting job setting via the operation panel 40. Then, when an instruction to start a job set to the thick paper mode is received via the operation panel 40, for example, the lift control unit 202 raises the left tray 311 from the height position P2 to the height position P3.

Next, a case where the left tray 311 is continuously raised from the initial position P1 to the height position P3 will be described. For example, when the document detection sensor 34 detects that a document has been placed on the left tray 311 and an instruction to start a job set to the thick paper mode is received via the operation panel 40, the lift control unit 202 continuously raises the left tray 311 from the initial position P1 to the height position P3.

As described above, in the thick paper mode, the left tray 311 may be raised in stages or continuously. Note that the left tray 311 may be raised in stages or continuously in the thin paper mode and business card mode as well as in the thick paper mode.

The flow relating to the lifting and lowering control of the left tray 311 before the start of the paper feed process will be described with reference to FIG. 11. FIG. 11 is an example of the flow relating to the lifting and lowering control before the start of the paper feed process by the control unit 200. In the flow shown in FIG. 11, it is assumed that the paper type can be set to plain paper mode and thick paper mode.

In S11, the document detection sensor 34 detects that a document has been placed on the left tray 311, and the process proceeds to S12. In S12, it is determined whether any (input operation) touch operation has been accepted via the operation unit. If a touch operation has been accepted in S12, that is, if S12 is Yes, the process proceeds to S13. If a touch operation has not been accepted in S12, that is, if S12 is No, the process returns to S12.

In S13, the left tray 311 is raised, and the process proceeds to S14. In S14, it is determined whether the upper limit sensor 32 has detected the detection piece 325d. If it is determined in S14 that the upper limit sensor 32 has detected the detection piece 325d, i.e., if S14 is Yes, the process proceeds to S15. If it is determined in S14 that the upper limit sensor 32 has not detected the detection piece 325d, i.e., if S14 is No, the process returns to S14. In S15, the left tray 311 is stopped, and the process proceeds to S16.

In S16, it is determined whether or not a job start instruction has been accepted. If it is determined in S16 that a job start instruction has been accepted, then if the answer is Yes in S16, proceed to S17. If it is determined in S16 that a job start instruction has not been accepted, that is, if the answer is No in S16, return to S16. In S17, it is determined whether or not the mode is thick paper. If it is determined in S17 that the mode is thick paper, that is, if the answer is Yes in S17, proceed to S18. If it is determined in S17 that the mode is not thick paper, that is, if the answer is No in S17, then the process ends. In S18, the left tray 311 is raised by a first predetermined amount A1, and the process ends.

Next, the lifting and lowering correction control of the left tray 311 during the paper feed process will be described. In the paper feed process, the paper feed motor 322b is driven to rotate the pickup roller 321 and the paper feed roller 322, so that the paper is fed one by one from the paper stack M on the left tray 311 into the transport path 330. Then, as the paper stack M on the left tray 311 gradually decreases and the height of the topmost paper stacked on the left tray 311 decreases, the pickup roller 321 is pressed by the pressing portion 325b and gradually lowers. As a result, the detection piece 325d lowers, and the upper limit sensor 32 no longer detects the detection piece 325d, so that the leading edge of the paper does not come into contact with the desired position of the guide member 326, and the paper may not be properly guided toward the paper feed roller 322.

Therefore, in the plain paper mode, when the upper limit sensor 32 no longer detects the detection piece 325d during the paper feed process, the lift control unit 202 controls the lift motor 371 to further raise the left tray 311 from the height position P2 before the start of the paper feed process to a height position at which the upper limit sensor 32 detects the detection piece 325d.

In addition, in the thick paper mode, when the upper limit sensor 32 no longer detects the detection piece 325d during the paper feeding process, the lift control unit 202 controls the lift motor 371 to be higher by a first predetermined amount A1 compared to the plain paper mode. Similarly, in the thin paper mode, the lift control unit 202 controls the lift motor 371 to be higher by a second predetermined amount A2 compared to the plain paper mode. In addition, in the business card mode, the lift control unit 202 controls the lift motor 371 to be higher by a third predetermined amount A3 compared to the plain paper mode.

As a result, even if the stack of paper M on the left tray 311 decreases during the paper feeding process and the position at which the leading edge of the paper abuts against the guide surface 326a becomes lower, the left tray 311 can be raised to raise the position at which the leading edge of the paper abuts, so that the paper can be fed to the paper feed roller 322 while preventing paper feeding failures.

The flow relating to the lift correction control of the left tray 311 during the paper feed process will be described using FIG. 12. FIG. 12 is an example of a flow relating to the lift correction control during the paper feed process by the control unit 200. In the flow shown in FIG. 12, it is assumed that the paper type can be set to plain paper mode and thick paper mode. In the flow shown in FIG. 12, it is assumed that the paper feed process by the control unit 200 has started.

In S21, it is determined whether the upper limit sensor 32 has stopped detecting the detection piece 325d. If it is determined in S21 that the upper limit sensor 32 has stopped detecting the detection piece 325d, i.e., if S21 is Yes, proceed to S22. If it is determined in S22 that the upper limit sensor 32 is detecting the detection piece 325d, i.e., if S21 is No, return to S21. In S22, it is determined whether or not the mode is cardboard mode. If it is determined in S22 that the mode is cardboard mode, i.e., if S22 is Yes, proceed to S23. If it is determined in S22 that the mode is not cardboard mode, i.e., if S22 is No, proceed to S26.

In S23, the left tray 311 is raised, and the process proceeds to S24. In S24, it is determined whether the upper limit sensor 32 has detected the detection piece 325d. If it is determined in S24 that the upper limit sensor 32 has detected the detection piece 325d, i.e., if Yes in S24, the process proceeds to S25. If it is determined in S24 that the upper limit sensor 32 has not detected the detection piece 325d, i.e., if No in S24, the process returns to S24. In S25, the left tray 311 is further raised by a first predetermined amount A1, and the process returns to S21.

In S26, the left tray 311 is raised, and the process proceeds to S27. In S27, it is determined whether the upper limit sensor 32 has detected the detection piece 325d. If it is determined in S27 that the upper limit sensor 32 has detected the detection piece 325d, i.e., if Yes in S27, the process proceeds to S28. If it is determined in S27 that the upper limit sensor 32 has not detected the detection piece 325d, i.e., if No in S27, the process returns to S27. In S28, the left tray 311 is stopped, and the process returns to S21.

Next, the lift correction control by the lift control unit 202 when a pick error is determined will be described. In the thick paper mode, the height position of the left tray 311 is higher than in the plain paper mode. That is, in the thick paper mode, the left tray 311 is located at a height position higher than the height position at which the upper limit sensor 32 detects the detection piece 325d. Therefore, as the number of sheets in the stack of sheets M decreases, the position at which the tip of the top sheet abuts against the guide member 326 is likely to change significantly until the upper limit sensor 32 no longer detects the detection piece 325d. Therefore, even if the upper limit sensor 32 detects the detection piece 325d, a pick error is more likely to occur due to increased slippage of the pickup roller 321.

When the control unit 200 determines that a pick error has occurred, it can execute a retry process to temporarily stop the drive of the paper feed motor 322b and then drive the paper feed motor 322b again.

The control unit 200 has a determination unit 203 that determines whether a pick error has occurred during the paper feed process. The determination unit 203 determines that a pick error has occurred when the paper feed sensor 35 does not detect that paper has been fed to the transport path 330 within a predetermined time after the paper feed motor 322b is driven to rotate the paper feed roller 322. The determination unit 203 determines that a pick error has not occurred when the paper feed sensor 35 detects that paper has been fed to the transport path 330 within a predetermined time after the paper feed motor 322b is driven to rotate the paper feed roller 322.

In the above configuration, in the thick paper mode, when it is determined that a pick error has occurred during the paper feed process, the lift control unit 202 lifts the left tray 311 by a predetermined amount. The predetermined amount is the amount until the height of the left tray 311 reaches a predetermined position that is a first predetermined amount A1 higher than the height position at which the upper limit sensor 32 detects the detection piece 325d. The timing at which the lift control unit 202 lifts the left tray 311 by the predetermined amount is the timing at which the control unit 200 executes the retry process, specifically, the timing after the drive of the paper feed motor 322b is temporarily stopped and before the paper feed motor 322b is driven again.

As described above, in the thick paper mode, by raising the left tray 311 by a predetermined amount when a pick error occurs, the position at which the leading edge of the paper abuts against the guide surface 326a can be raised, so that the paper can be fed to the paper feed roller 322 while preventing paper feed failures.

On the other hand, in the plain paper mode, when a pick error occurs, unlike the thick paper mode, the left tray 311 is not raised and a retry process is executed. In the plain paper mode, the height position of the left tray 311 is lower than in the thick paper mode, so the position where the tip of the topmost paper abuts against the guide member 326 does not change significantly until the upper limit sensor 32 no longer detects the detection piece 325d due to the paper in the paper stack M decreasing. Therefore, in the plain paper mode, if the left tray 311 is raised when a pick error occurs, there is a possibility that the distance for the topmost paper to run up the guide surface 326a will not be sufficiently secured. Therefore, in the plain paper mode, the left tray 311 is not raised and a retry process is executed, so that the paper can be fed to the paper feed roller 322 while securing the distance for the topmost paper to run up the guide surface 326a.

In addition, in the thick paper mode, the left tray 311 is raised by a predetermined amount when a pick error occurs, but this is not limited to the above, and in the business card mode, the left tray 311 may be raised by a predetermined amount when a pick error occurs. In this case, the predetermined amount is the amount until the height of the left tray 311 reaches a predetermined position that is a third predetermined amount A3 higher than the height position at which the upper limit sensor 32 detects the detection piece 325d.

The flow relating to the lifting and lowering correction control of the left tray 311 when a pick error is determined will be described using FIG. 13. FIG. 13 is an example of a flow relating to the lifting and lowering correction control when a pick error is determined by the control unit 200. In the flow shown in FIG. 13, it is assumed that the plain paper mode and the thick paper mode can be set as the paper type. In the flow shown in FIG. 13, it is assumed that the paper feeding process by the control unit 200 has started.

In S31, it is determined whether the upper limit sensor 32 detects the detection piece 325d. If it is determined in S31 that the upper limit sensor 32 detects the detection piece 325d, i.e., if S31 is Yes, proceed to S32. If it is determined in S32 that the upper limit sensor 32 does not detect the detection piece 325d, i.e., if S31 is No, return to S31. In S32, it is determined whether a pick error has occurred. If it is determined in S32 that a pick error has occurred, i.e., if S32 is Yes, proceed to S33. If it is determined in S32 that a pick error has not occurred, i.e., if S32 is No, return to S31.

In S33, the rotation of the paper feed roller 322 is stopped, and the process proceeds to S34. In S34, it is determined whether or not the mode is thick paper mode. If it is determined in S34 that the mode is thick paper mode, i.e., if S34 is Yes, the process proceeds to S35. If it is determined in S34 that the mode is not thick paper mode, i.e., if S34 is No, the process proceeds to S36. In S35, the left tray 311 is raised a predetermined amount, and the process proceeds to S36. In S36, the paper feed roller 322 is rotated again, paper feed processing is resumed, and the process returns to S31.

Next, we will explain the first modified example of the elevation correction control during the paper feed process.

The control unit 200 has a counting unit 204 that counts the number of sheets fed, which is the number of sheets of paper fed to the transport path 330 by the paper feed unit 320. The counting unit 204 counts the number of sheets fed when the paper feed process is started. In addition, the counting unit 204 resets the count of the number of sheets fed when the number of sheets fed reaches a predetermined threshold value.

In the thick paper mode, when the upper limit sensor 32 detects the detection piece 325d and it is determined that the number of fed sheets has reached a predetermined threshold, the lift control unit 202 controls the lift motor 371 to raise the left tray 311 by a predetermined amount. Here, the predetermined amount is set based on, for example, the value obtained by multiplying the thickness of the thick paper by the number of fed sheets.

This allows the left tray 311 to be raised each time a certain number of sheets of paper stack M on the left tray 311 is reduced, preventing the position where the leading edge of the paper contacts the guide surface 326a from being lowered too far. Therefore, even if the upper limit sensor 32 detects the detection piece 325d, it is possible to effectively prevent picking errors caused by increased slippage of the pickup roller 321.

Note that while the above-mentioned lifting and lowering control of the left tray 311 during the paper feeding process has been described using the second paper (thick paper), this is not limited to this and can also be applied, for example, to the case where the third paper (thin paper) or the fourth paper (thick paper for business cards) is used.

The flow of the first modified example of the lift correction control of the left tray 311 during the paper feed process will be described with reference to FIG. 14. FIG. 14 is an example of the flow of the first modified example of the lift correction control during the paper feed process by the control unit 200. In the flow shown in FIG. 14, it is assumed that the paper type can be set to plain paper mode and thick paper mode. In the flow shown in FIG. 14, it is assumed that the paper feed process by the control unit 200 has started. In the flow shown in FIG. 14, it is assumed that the upper limit sensor 32 is detecting the detection piece 325d.

In S41, it is determined whether the number of sheets fed has reached a predetermined threshold. If it is determined in S41 that the number of sheets fed has reached the predetermined threshold, i.e., if S41 is Yes, proceed to S42. If it is determined in S41 that the number of sheets fed has not reached the predetermined threshold, i.e., if S41 is No, return to S41.

In S42, it is determined whether or not the mode is thick paper. If it is determined in S42 that the mode is thick paper, i.e., if S42 is Yes, proceed to S43. If it is determined in S42 that the mode is not thick paper, i.e., if S43 is No, proceed to S44. In S43, the left tray 311 is raised by a predetermined amount, and proceed to S44. In S44, the count of the number of sheets fed is reset, and the process returns to S41.

In the above configuration, the paper feed device (original transport unit 30) comprises a tray (left tray 311) on which paper can be placed, a feed roller (pickup roller 321) that feeds the paper placed on the tray (left tray 311), a paper feed roller 322 that feeds the fed paper to the transport path 330, a guide member 326 that guides the paper fed from the tray (left tray 311) toward the paper feed roller 322 and is arranged at an upward incline as it approaches the paper feed roller 322, a lifting mechanism 370 that can change the height of the tray (left tray 311), and a control unit 200 that performs a paper feed process that feeds the paper fed from the tray (left tray 311) to the transport path 330 by rotating the paper feed roller 322. The control unit 200 has a setting unit 201 that accepts job settings including settings for multiple types of paper including a first paper (plain paper) and a second paper (thick paper) that is thicker than the first paper (plain paper), and a lift control unit 202 that controls the lift mechanism 370 so that when the second paper (thick paper) is set, the height of the tray (left tray 311) relative to the guide member 326 is higher by a first predetermined amount A1 before the start of the paper feeding process compared to when the first paper (plain paper) is set.

This reduces the distance that the topmost sheet of paper (cardboard) fed by the feed roller (pickup roller 321) runs up along the guide member 326. Therefore, it is possible to guide the sheet of paper (cardboard) toward the feed roller 322 while reducing pick errors.

In the above configuration, the paper feed device (original transport unit 30) includes a tray (left tray 311) on which paper can be placed, a feed roller (pickup roller 321) that feeds the paper placed on the tray (left tray 311), a paper feed roller 322 that feeds the fed paper to the transport path 330, a guide member 326 that guides the paper fed from the tray (left tray 311) toward the paper feed roller 322 and is inclined upward as it approaches the paper feed roller 322, a lifting mechanism 370 that can change the height of the tray (left tray 311), and a paper feed roller 322 that rotates to feed the paper fed from the tray (left tray 311). A paper feeding method for a paper feeder (original transport unit 30) including a control unit 200 that executes a paper feeding process to feed paper that has been removed from the paper feeder to a transport path 330, in which the control unit 200 has a setting step for accepting job settings including settings for multiple types of paper including a first paper (plain paper) and a second paper (thick paper) that is thicker than the first paper (plain paper), and a lift control step for controlling the lift mechanism 370 so that when the second paper (thick paper) is set, the height of the tray (left tray 311) relative to the guide member 326 is higher by a first predetermined amount A1 before the start of the paper feeding process compared to when the first paper (plain paper) is set.

The paper feed device (original transport unit 30) is further provided with a first detection unit (paper passage sensor 35) disposed downstream of the paper feed roller 322 and detecting the paper fed by the paper feed roller 322. When the first detection unit (paper passage sensor 35) does not detect the paper fed during the paper feed process, the control unit 200 can execute a retry process to stop the paper feed process and then resume the paper feed process. When the second paper (thick paper) is set and the paper fed by the first detection unit (paper passage sensor 35) is not detected during the paper feed process, the lift control unit 202 controls the lift mechanism 370 to further lift the tray (left tray 311) by a predetermined amount relative to the guide member 326 after stopping the paper feed process in the retry process and before resuming the paper feed process. As a result, even if the stack of paper M on the tray (left tray 311) decreases during the paper feed process and the position where the leading edge of the paper abuts against the guide member 326 becomes lower, the tray (left tray 311) can be raised to raise the position where the leading edge of the paper abuts, so that the paper can be fed to the paper feed roller 322 while preventing paper feed failures.

The paper feed device (original transport unit 30) is further provided with a first detection unit (paper passing sensor 35) disposed downstream of the paper feed roller 322 and detecting the paper fed by the paper feed roller 322. When the first detection unit (paper passing sensor 35) does not detect the paper being fed during the paper feed process, the control unit 200 can execute a retry process to stop the paper feed process and then resume the paper feed process. When the first paper (plain paper) is set and the first detection unit (paper passing sensor 35) does not detect the paper being fed during the paper feed process, the lift control unit 202 executes the retry process without lifting the tray (left tray 311) relative to the guide member 326. As described above, in the plain paper mode, by executing the retry process without lifting the left tray 311, the paper can be fed to the paper feed roller 322 while ensuring the distance that the topmost paper fed runs up the guide surface 326a.

The control unit 200 further includes a counting unit 204 that counts the number of sheets fed, which is the number of sheets fed by the feed roller 322. When the second sheet (thick paper) is set and the number of sheets fed is determined to be equal to or greater than a predetermined threshold during the feed process, the lift control unit 202 controls the lift mechanism 370 to further raise the tray (left tray 311) relative to the guide member 326. This allows the tray (left tray 311) to be raised each time a certain number of sheets of paper stack M on the tray (left tray 311) is reduced, thereby preventing the position where the leading edge of the paper abuts against the guide member 326 from being lowered too much. Therefore, even if the upper limit sensor 32 detects the detection piece 325d, it is possible to effectively prevent picking errors caused by increased slippage of the feed roller (pickup roller 321).

The paper feeder (original transport unit 30) further includes a second detection unit (original detection sensor 34) that detects paper placed on the tray (left tray 311). When the lift control unit 202 detects paper placed on the tray (left tray 311) and receives an instruction to start a job set for the second paper (thick paper) via the operation unit (operation panel 40), it continuously lifts the tray (left tray 311) from the initial position P1 to a height position P3 when the second paper (thick paper) is set.

The paper feeder (original transport unit 30) further includes a second detection unit (original detection sensor 34) that detects paper placed on the tray (left tray 311). When the lift control unit 202 detects paper placed on the tray (left tray 311) and receives any operation input via the operation unit (operation panel 40), it lifts the tray (left tray 311) from the initial position P1 to a height position P2 when the first paper (plain paper) is set, and when an instruction to start a job set for the second paper (thick paper) is received via the operation unit (operation panel 40), it lifts the tray (left tray 311) from the height position P2 when the first paper (plain paper) is set to a height position P3 when the second paper (thick paper) is set.

The guide member 326 has a guide surface 326a that is inclined upward toward the paper feed roller 322. The lift control unit 202 controls the lift mechanism 370 so that when the second paper (thick paper) is set, the angle of the loading surface on which the paper of the tray (left tray 311) is placed relative to the guide surface 326a is smaller than when the first paper (plain paper) is set. This reduces the resistance when the leading edge of the paper on the tray (left tray 311) abuts against the guide surface 326a, thereby preventing pick errors.

The setting unit 201 can accept settings for a third paper (thin paper) that is thinner than the first paper (plain paper) as a setting for multiple types of paper. When the third paper (thin paper) is set, the lift control unit 202 controls the lift mechanism 370 so that the height of the tray (left tray 311) relative to the guide member 326 before the start of the paper feed process is higher by a second predetermined amount A2, which is smaller than the first predetermined amount A1, compared to when the first paper (plain paper) is set. This makes it possible to reduce the distance that the topmost paper fed by the feed roller (pickup roller 321) runs up the guide member 326 while maintaining a certain degree of distance. Therefore, the paper can be guided toward the paper feed roller 322 while suppressing damage to the paper and double feeds.

The setting unit 201 can accept settings for a fourth paper (cardboard for business cards) that is thicker and smaller than the first paper (plain paper) as settings for multiple types of paper. When the fourth paper (cardboard for business cards) is set, the lift control unit 202 controls the lift mechanism 370 so that the height of the tray (left tray 311) relative to the guide member 326 before the start of the paper feed process is higher by a third predetermined amount A3, which is greater than the first predetermined amount A1, compared to when the first paper (plain paper) is set. This makes it possible to reduce the distance that the topmost paper fed by the feed roller (pickup roller 321) runs up the guide member 326. Therefore, it is possible to guide the paper toward the paper feed roller 322 while suppressing pick errors.

The image forming device 1 also includes a paper feeder (document transport unit 30).

The program also causes the computer to operate as the control unit 200 of the image forming device 1 (document transport unit 30).

The above-mentioned paper feed device (original transport unit 30) is a device for feeding paper to the image reading unit 20, but is not limited to this and may be a device for feeding paper to the printing unit 10. In this case, for example, the paper feed device may be configured to have the paper feed unit 110 of the printing unit 10, or may be configured to have a manual feed tray for feeding paper to the printing unit 10.

The above-mentioned paper feeding device (document transport unit 30) can be realized by hardware, software, or a combination of these. The above-mentioned paper feeding method can also be realized by hardware, software, or a combination of these. Here, being realized by software means being realized by a computer reading and executing a program.

The program can be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-R/Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (random access memory)). The program may also be provided to the computer by various types of temporary computer readable media. Examples of temporary computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer readable medium can provide the program to the computer via a wired communication path such as an electrical wire or optical fiber, or via a wireless communication path.

1 Image forming device, 30 Document transport unit, 34 Document detection sensor (second detection unit), 35 Paper passing sensor (first detection unit), 40 Operation panel (operation unit), 200 Control unit, 201 Setting unit, 202 Lifting control unit, 204 Counting unit, 311 Left tray (tray), 321 Pickup roller (feed roller), 322 Paper feed roller, 326 Guide member, 326a Guide surface, 330 Transport path, 370 Lifting mechanism, A1 First predetermined amount, A2 Second predetermined amount, A3 Third predetermined amount, P1 Initial position, P2 Height position, P3 Height position

Claims (10)

a tray on which paper can be placed;
a feed roller for feeding the paper placed on the tray;
a paper feed roller that feeds the fed paper to a conveyance path;
a guide member that guides the paper fed from the tray toward the paper feed roller and is inclined upward as it approaches the paper feed roller;
A lifting mechanism capable of changing the height of the tray;
a control unit that executes a paper feed process to feed the paper fed from the tray to the conveying path by rotating the paper feed roller,
The control unit is
a setting unit that receives job settings including settings related to a plurality of types of paper including a first paper and a second paper having a thickness greater than that of the first paper;
a lifting/lowering control unit that controls the lifting mechanism so that when the second paper is set, the height of the tray relative to the guide member is higher by a first predetermined amount before the start of the paper feeding process, compared to when the first paper is set. a first detection unit disposed downstream of the paper feed roller and configured to detect the paper being fed by the paper feed roller;
the control unit is capable of executing a retry process of stopping the paper feeding process and then restarting the paper feeding process when the paper to be fed is not detected by the first detection unit during the paper feeding process,
The lift control unit is
When the second paper is set,
2. The paper feeding device of claim 1, wherein if the first detection unit does not detect the paper being fed during the paper feeding process, the lifting mechanism is controlled to further lift the tray a predetermined amount relative to the guide member after the paper feeding process in the retry process is stopped and before the paper feeding process is resumed. a first detection unit disposed downstream of the paper feed roller and configured to detect the paper being fed by the paper feed roller;
the control unit is capable of executing a retry process of stopping the paper feeding process and then restarting the paper feeding process when the paper to be fed is not detected by the first detection unit during the paper feeding process,
The lift control unit is
When the first paper is set,
3 . The paper feeding device according to claim 1 , wherein, when the fed paper is not detected by the first detection unit during the paper feeding process, the retry process is performed without lifting the tray relative to the guide member. The control unit is
A counting unit is further provided for counting the number of sheets fed, which is the number of sheets fed by the sheet feed roller,
The lift control unit is
When the second paper is set,
3 . The paper feed device according to claim 1 , further comprising: a controller configured to control the lifting mechanism so as to further lift the tray relative to the guide member when it is determined that the number of fed sheets is equal to or greater than a predetermined threshold during the paper feed process. A second detection unit that detects the paper placed on the tray is further provided.
The lift control unit is
When a sheet placed on the tray is detected and an instruction to start the job set for the second sheet is received via an operation unit,
3. The paper feed device according to claim 1, wherein the tray is continuously raised from an initial position to a height position when the second paper is set. A second detection unit that detects the paper placed on the tray is further provided.
The lift control unit is
detecting a sheet placed on the tray and, when any operation input is received via an operation unit, raising the tray from an initial position to a height position when the first sheet is set;
3. A paper feeding device as described in claim 1 or claim 2, wherein when an instruction to start the job set on the second paper is accepted via the operation unit, the tray is raised from a height position when the first paper is set to a height position when the second paper is set. the guide member has a guide surface that is inclined upward toward the paper feed roller,
The lift control unit is
3. The paper feeding device according to claim 1, wherein the lifting mechanism is controlled so that when the second paper is set, the angle of the loading surface on which the paper of the tray is placed relative to the guide surface is smaller than when the first paper is set. the setting unit is capable of receiving a setting for a third sheet of paper having a thickness smaller than that of the first sheet of paper as a setting for the plurality of types of paper;
The lift control unit is
3. The paper feeding device according to claim 1, wherein when the third paper is set, the lifting mechanism is controlled so that the height of the tray relative to the guide member is higher by a second predetermined amount that is smaller than the first predetermined amount before the paper feeding process begins, compared to when the first paper is set. the setting unit is capable of receiving, as a setting for the plurality of types of paper, a setting for a fourth paper sheet having a thickness larger than that of the first paper sheet and a size smaller than that of the first paper sheet;
The lift control unit is
3. The paper feeding device according to claim 1, wherein when the fourth paper is set, the lifting mechanism is controlled so that the height of the tray relative to the guide member before the start of the paper feeding process is higher by a third predetermined amount that is greater than the first predetermined amount, compared to when the first paper is set. An image forming apparatus equipped with the paper feeder according to claim 1 or 2.

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