Sheet conveying device and image processing device

Abstract

To provide a sheet conveying device and an image processing device that are less likely to cause erroneous detection.SOLUTION: A sheet conveying device 2 includes a sheet stacking tray, a sheet discharge tray, a conveying mechanism 3, a lifting mechanism 4, a jump sensor 6, and a sensitivity setting unit 25. The conveying mechanism 3 takes in a sheet placed on the sheet stacking tray through an inlet and conveys it onto the sheet discharge tray via an execution position where image processing is performed by an image processing unit. The lifting mechanism 4 raises and lowers the sheet stacking tray 21. The jump sensor 6 monitors an area above the inlet and detects an object in the monitoring area based on an output of a light receiving unit which varies depending on the amount of light emitted from a light emitting unit and entering the light receiving unit through the monitoring area. The sensitivity setting unit 25 changes the sensitivity of the jump sensor 6 when a sheet is taken in through the inlet and when the sheet stacking tray is raised.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device and an image processing device. [Background technology]

[0002] As a related technology, a sheet conveying (feeding) device is known that includes a sheet stacking tray (sheet stacking means) on which sheets are stacked, and a conveying mechanism (sheet taking-in means and separation feeding means) that takes in the sheets stacked on the sheet stacking tray and conveys (feeds) them one by one (see, for example, Patent Document 1).

[0003] A sheet transport device according to the related art further includes a jump sensor (sheet abnormality detection means) that detects a sheet jumping up on the sheet stacking table. The jump sensor has a light-emitting unit that emits light and a light-receiving unit that receives the light emitted by the light-emitting unit, and detects an obstacle when an obstacle blocks the optical path of the light emitted from the light-emitting unit until it reaches the light-receiving unit. This allows the sheet transport device to detect a jumping up of a sheet when taking in a sheet and stop conveying the sheet, and to detect a hand or other object as an obstacle when raising the sheet stacking table and stop raising the sheet stacking table to prevent the hand or other object from getting caught. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-62202 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration of the related technology described above, the jump sensor detects obstacles in the optical path from when light is emitted from the light-emitting element to when it reaches the light-receiving element. For example, if a Z-folded document (a sheet folded in a Z shape) is detected when the sheet stacking tray is being raised, the raising of the sheet stacking tray may be stopped.

[0006] An object of the present invention is to provide a sheet conveying device and an image processing device that are less likely to cause erroneous detection. [Means for solving the problem]

[0007] According to one aspect of the present invention, a sheet transport device includes a sheet stacking tray, a sheet discharge tray, a transport mechanism, a lifting mechanism, a jump sensor, and a sensitivity setting unit. The transport mechanism takes in a sheet placed on the sheet stacking tray through an inlet and transports it onto the sheet discharge tray via an execution position where an image processing unit performs image processing. The lifting mechanism raises and lowers the sheet stacking tray. The jump sensor monitors an area above the inlet and detects a detection target in the monitoring area based on the output of the light receiving unit, which varies depending on the amount of light emitted from a light emitting unit and incident on a light receiving unit through the monitoring area. The sensitivity setting unit changes the sensitivity of the jump sensor when the sheet is taken in through the inlet and when the sheet stacking tray is raised.

[0008] An image processing apparatus according to another aspect of the present invention includes the sheet conveying device and the image processing unit that performs at least one of reading an image and forming an image on the sheet. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a sheet conveying device and an image processing device that are less likely to cause erroneous detection. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the external appearance and internal configuration of an image processing device according to the first embodiment. [Figure 2] FIG. 2 is a schematic block diagram of the image processing device according to the first embodiment. [Figure 3] FIG. 3 is a schematic diagram illustrating the appearance and internal configuration of the sheet conveying device according to the first embodiment. [Figure 4]FIG. 4 is a schematic perspective view showing the appearance of the sheet conveying device according to the first embodiment. [Figure 5] FIG. 5 is a schematic diagram illustrating an example of the configuration of a main part of the sheet conveying device according to the first embodiment. [Figure 6] FIG. 6 is a graph showing an example of characteristics of the detection operation of the jump-up sensor in the sheet conveying device according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description will discuss preferred embodiments of the present invention with reference to the accompanying drawings. The preferred embodiments are merely examples of the present invention and are not intended to limit the technical scope of the present invention.

[0012] (Embodiment 1) [1] Overall configuration of image processing device First, the overall configuration of an image processing device 10 according to this embodiment will be described with reference to FIGS.

[0013] For ease of explanation, the vertical direction in the installation state where the image processing device 10 is usable (the state shown in FIG. 1) is defined as the up-down direction D1. Furthermore, the direction perpendicular to the plane of the image processing device 10 shown in FIG. 1 is defined as the front-back direction D2, and the surface on the front side in FIG. 1 is defined as the front (front face). Furthermore, the surface on the left side of the plane of FIG. 1 is defined as the left side, and the left-right direction D3 is defined.

[0014] The image processing device 10 according to this embodiment is, for example, a multifunction peripheral having multiple functions, such as a scanning function for acquiring an image (image data) from an original, a printing function for forming an image based on the image data, a facsimile function, and a copying function. The image processing device 10 may be a printer, scanner, facsimile machine, copier, etc., as long as it has an image processing function including at least one of an image forming function and an image reading function.

[0015] 1, the image processing device 10 includes a sheet conveying device 2, an image reading unit 11, an image forming unit 12, a paper feed unit 13, an operation display unit 14, and a control unit 15. In this embodiment, the image processing device 10 includes a housing 100, as shown in FIG. 2. The ADF 11, the image reading unit 11, the image forming unit 12, the paper feed unit 13, the operation display unit 14, and the control unit 15 are provided in the housing 100.

[0016] In this embodiment, the sheet transport device 2 is an automatic document feeder (ADF). The sheet transport device 2 transports a sheet Sh1 (document) as a reading object (image processing object) whose image is to be read by the image reading unit 11. The sheet transport device 2 has a sheet stacking tray 21, a sheet discharge tray 22, a transport mechanism 3, a lifting mechanism 4, a set sensor 5, a jump-up sensor 6, etc. By driving the transport mechanism 3, the sheet transport device 2 transports the sheet Sh1 set on the sheet stacking tray 21 to the sheet discharge tray 22, passing through an image reading position by the image reading unit 11.

[0017] The image reading unit 11 reads an image from a sheet Sh1 (original) and outputs image data corresponding to the read image. The image reading unit 11 includes a document table, a light source, a plurality of mirrors, an optical lens, a CCD (Charge Coupled Device), and the like.

[0018] The image forming unit 12 forms an image on the sheet Sh2 based on image data output from the image reading unit 11. The image forming unit 12 also forms an image on the sheet Sh2 based on image data input from an information processing device external to the image processing device 10, such as a personal computer. As an example, in this embodiment, as shown in FIG. 1 , the image forming unit 12 includes a transfer device 121, a fixing device 122, and a paper output tray 123, and forms an image on the sheet Sh2 by electrophotography. The image forming unit 12 is not limited to a configuration that forms a monochrome image, and may also be configured to form a full-color image using four colors: C (cyan), M (magenta), Y (yellow), and K (black). The image forming unit 12 may also be configured to form an image on the sheet by an image forming method other than electrophotography, such as an inkjet method.

[0019] The image forming unit 12 forms an image on the sheet Sh2 using toner as a developer. Specifically, the image forming unit 12 forms an electrostatic latent image on the surface of a charged photosensitive drum by irradiating the surface with laser light, and develops the electrostatic latent image with toner to form a toner image on the surface of the photosensitive drum. A transfer device 121 transfers the toner image to the sheet Sh2 being transported along a transport path. A fixing device 122 melts and fixes the toner image transferred to the sheet Sh2 to the sheet Sh2. For example, the fixing device 122 includes a fixing roller and a pressure roller, and heats the toner image transferred to the sheet Sh2 and applies pressure to the sheet Sh2 to fix the toner image to the sheet Sh2. The sheet Sh2 after image formation is discharged to a paper output tray 123. When the image forming unit 12 forms an image using an inkjet system, ink (another example of a developer) is supplied instead of toner.

[0020] The paper feed unit 13 supplies the sheet Sh2 to the image forming unit 12. The paper feed unit 13 has a plurality of paper feed cassettes 131, a manual feed tray, a plurality of transport rollers, etc. The paper feed unit 13 transports the sheet Sh2 from the plurality of paper feed cassettes 131 or the manual feed tray, etc., through a transport path using a plurality of transport rollers, etc., and supplies the sheet Sh2 to the image forming unit 12. The image forming unit 12 forms an image on the sheet Sh2 supplied from the paper feed unit 13 through the transport path.

[0021] The operation display unit 14 is a user interface in the image processing device 10. The operation display unit 14 has a display unit such as a liquid crystal display that displays various information in response to control instructions from the control unit 15, and an operation unit such as a switch or touch panel that inputs various information to the control unit 15 in response to user operations. The image processing device 10 may also include, for example, an audio output unit and an audio input unit as a user interface in addition to or instead of the operation display unit 14. The operation display unit 14 may also be, for example, an external device provided separately from the housing 100. In this case, the image processing device 10 can use the operation display unit 14 as a user interface by performing data communication with the external device.

[0022] The control unit 15 performs overall control of the image processing device 10. The control unit 15 is primarily configured as a computer system having one or more processors and one or more memories. In the image processing device 10, the functions of the control unit 15 are realized by the one or more processors executing programs. The programs may be pre-recorded in one or more memories, provided via a telecommunications line such as the Internet, or provided by being recorded on a non-transitory recording medium readable by a computer system, such as a memory card or an optical disk. The one or more processors are composed of one or more electronic circuits including semiconductor integrated circuits. Furthermore, the computer system referred to in this disclosure includes a microcontroller having one or more processors and one or more memories. The control unit 15 may be a control unit provided separately from the main control unit that performs overall control of the image processing device 10.

[0023] The image processing device 10 further includes a storage unit, a communication unit, a power supply unit, etc. The storage unit includes one or more non-volatile memories and stores information such as control programs for causing the control unit 15 to execute various processes. The communication unit is an interface that executes data communication between the image processing device 10 and an external device connected via a communication network such as the Internet or a LAN (Local Area Network). The power supply unit is a power supply circuit that generates (outputs) power for the operation of the image processing device 10.

[0024] Here, the sheet conveying device 2 according to this embodiment, together with the image processing unit (image reading unit 11 and image forming unit 12), constitutes the image processing device 10. In other words, the image processing device 10 according to this embodiment includes the sheet conveying device 2 and an image processing unit that performs at least one of image reading and image formation on the sheet Sh1.

[0025] [2] Sheet transport device Next, the configuration of the sheet conveying device 2 according to this embodiment will be described in more detail with reference to FIGS.

[0026] The sheet conveying device 2 is a device that conveys a sheet Sh1 from the sheet stacking tray 21 to the sheet discharge tray 22. Here, the term "sheet" in the present disclosure refers to a sheet on which an image is to be read or an image is to be formed. In the present embodiment, as an example, the sheet Sh1 to be conveyed by the sheet conveying device 2 is a sheet Sh1 (original) on which an image is to be read by the image reading unit 11. That is, in the present embodiment, the sheet conveying device 2 conveys the sheet Sh1 placed on the sheet stacking tray 21 onto the sheet discharge tray 22 through an execution position P1 (see FIG. 3 ) where image processing (image reading) is performed by the image reading unit 11 as an image processing unit. Therefore, the image reading position by the image reading unit 11 corresponds to the execution position P1. In addition, in the present embodiment, the sheet Sh1 is paper as an example, but is not limited to paper and may be, for example, a resin film or the like.

[0027] In this embodiment, the sheet conveying device 2 includes a sheet stacking tray 21, a sheet discharge tray 22, a conveying mechanism 3, a lifting mechanism 4, a set sensor 5, and a jump sensor 6, as well as a lifting / lowering control unit 23, a conveying control unit 24, and a sensitivity setting unit 25. The lifting / lowering control unit 23, the conveying control unit 24, and the sensitivity setting unit 25 are provided in the control unit 15 as one function of the control unit 15. In other words, in this embodiment, the image processing device 10 includes the lifting / lowering control unit 23, the conveying control unit 24, and the sensitivity setting unit 25 included in the sheet conveying device 2 as one function of the control unit 15.

[0028] The sheet stacking table 21 is a member on which the sheet Sh1 to be transported by the sheet transporting device 2 is placed. In this embodiment, the sheet Sh1 transported by the sheet transporting device 2 is the sheet Sh1 (original) whose image is to be read by the image reading unit 11, and therefore the sheet Sh1 whose image has not yet been read by the image reading unit 11 is set on the upper surface of the sheet stacking table 21.

[0029] Here, sheets Sh1 of various sizes (paper sizes), such as A3E (A3 size horizontal), B4E (A4 size horizontal), 2L size, L size, postcards, or business cards, can be set on the sheet stacking tray 21. The sheet stacking tray 21 has a pair of cursors facing each other in the front-to-rear direction D2, and the distance between the pair of cursors is adjusted according to the dimension of the set sheet Sh1 in the horizontal direction (here, the front-to-rear direction D2) perpendicular to the vertical direction (conveyance direction).

[0030] One or more sheets Sh1 to be conveyed by the sheet conveying device 2 are set on the sheet stacking tray 21. When multiple sheets Sh1 are set on the sheet stacking tray 21, these multiple sheets Sh1 are placed on the sheet stacking tray 21 in a state where they are overlapped in the vertical direction D1, that is, in a stacked state.

[0031] The sheet discharge tray 22 is a member on which the sheet Sh1 conveyed by the sheet conveying device 2 is placed. The sheet discharge tray 22 is located below the sheet stacking tray 21. The sheet conveying device 2 conveys the sheet Sh1 placed on the sheet stacking tray 21 through an execution position P1 where image processing is executed by the image processing unit, and discharges the sheet Sh1 onto the sheet discharge tray 22. In this embodiment, the sheet Sh1 conveyed by the sheet conveying device 2 is the sheet Sh1 (original) whose image is to be read by the image reading unit 11, and therefore the sheet Sh1 after the image reading by the image reading unit 11 is discharged onto the upper surface of the sheet discharge tray 22.

[0032] Here, sheets Sh1 of various sizes (paper sizes) can be placed on the sheet discharge tray 22, similar to the sheet stacking tray 21. Furthermore, when multiple sheets Sh1 are discharged onto the sheet discharge tray 22, similar to the sheet stacking tray 21, these multiple sheets Sh1 are placed on the sheet discharge tray 22 in a state where they are overlapped in the vertical direction D1, that is, in a stacked state.

[0033] 3, the conveying mechanism 3 takes in the sheet Sh1 placed on the sheet stacking tray 21 through the inlet 30 and conveys it onto the sheet discharge tray 22 through the execution position P1. That is, as indicated by the dashed arrow in FIG. 3, the conveying mechanism 3 takes in the sheet Sh1 through the inlet 30 that opens at the left end side of the sheet stacking tray 21, conveys it leftward and downward, turns it back to the right, and discharges it onto the sheet discharge tray 22 through the execution position P1. In other words, the conveying path of the sheet Sh1 by the conveying mechanism 3 includes the inlet 30 and the execution position P1 where image processing by the image processing unit (image reading by the image reading unit 11 in this embodiment) is performed.

[0034] The transport mechanism 3 includes, for example, a plurality of transport rollers 31 and a power source. The transport mechanism 3 drives each of the plurality of transport rollers 31 using power from a power source including, for example, a motor, to transport the sheets Sh1 set on the sheet stacking tray 21 one by one through the execution position P1 to the sheet discharge tray 22. For example, when a predetermined number of sheets Sh1 to be processed in a job are set on the sheet stacking tray 21, the transport mechanism 3 transports these sheets Sh1 one by one until all of the predetermined number of sheets Sh1 are discharged onto the sheet discharge tray 22. As a result, the predetermined number of sheets Sh1 to be processed in the job move from the sheet stacking tray 21 onto the sheet discharge tray 22 located below it.

[0035] Specifically, the transport mechanism 3 transports the sheets Sh1, one by one, that are placed on the sheet stacking tray 21 with their leading edge (left edge) inserted into the inlet 30. The transport mechanism 3 brings the transport roller 311, of the multiple transport rollers 31, that is closest to the inlet 30 into contact with the upper surface of the sheet Sh1 placed on the sheet stacking tray 21 from above, and drives the transport roller 311 to transport the sheet Sh1 on the sheet stacking tray 21 so as to pull it in. Therefore, when multiple sheets Sh1 are set on the sheet stacking tray 21, the multiple sheets Sh1 are transported one by one by the transport mechanism 3, starting from the topmost sheet Sh1, that is, the first sheet Sh1 from the top.

[0036] The lifting mechanism 4 raises and lowers (lifts and lowers) the sheet stacking platform 21. That is, the sheet stacking platform 21 is configured to be movable in the up-down direction D1 at least within a predetermined lifting range. Specifically, the lifting mechanism 4 is configured to be able to switch between an upward movement, which moves the sheet stacking platform 21 upward relative to the housing 100, and a downward movement, which moves the sheet stacking platform 21 downward. Furthermore, when neither the lifting movement nor the downward movement is being performed, the lifting mechanism 4 supports the sheet stacking platform 21 at any position within the lifting range.

[0037] In particular, in this embodiment, an initial position is defined between the upper limit (top dead center) and the lower limit (bottom dead center) of the lifting range, and the lifting mechanism 4 supports the sheet stacking tray 21 at the initial position during steady state operation, including when the image processing apparatus 10 is not operating. Furthermore, the lifting mechanism 4 can continuously move the sheet stacking tray 21 in the up-down direction D1 and can stop the sheet stacking tray 21 at any position within the lifting range. Therefore, by performing an upward movement of the lifting mechanism 4, the sheet stacking tray 21, which is in the initial position, can be moved to any position between the initial position and the upper limit of the lifting range. Conversely, by performing a downward movement of the lifting mechanism 4, the sheet stacking tray 21, which is in the initial position, can be moved to any position between the initial position and the lower limit of the lifting range.

[0038] Specifically, the lifting mechanism 4 includes appropriate mechanisms, such as a ball screw, a rack and pinion, and a pantograph, as well as a power source. The lifting mechanism 4 drives the mechanisms with power from a power source, such as a motor, to move the sheet stacking platform 21 linearly in the up-down direction D1. Preferably, the lifting mechanism 4 includes a sensor, such as an encoder, in the mechanisms or power source to detect the current position of the sheet stacking platform 21. This allows the lifting mechanism 4 to raise and lower the sheet stacking platform 21 only within a lifting range and also return it to its initial position. Furthermore, the lifting mechanism 4 preferably includes a function to detect the load on the output of the power source. This allows the lifting mechanism 4 to stop the sheet stacking platform 21 or move it in the opposite direction if an overload occurs, such as when a foreign object (e.g., a part of the user's body) gets caught during the lifting or lowering of the sheet stacking platform 21.

[0039] However, the lifting mechanism 4 is only required to have the function of lifting and lowering the sheet stacking platform 21, and the detailed configuration of the lifting mechanism 4 described above is not essential to the sheet conveying device 2. For example, it is not essential to move the sheet stacking platform 21 in a continuous manner, and the sheet stacking platform 21 may be moved in stages. Furthermore, it is not essential that the lifting mechanism 4 have an initial position defined within the lifting range, and the sheet stacking platform 21 may always be supported at an arbitrary position. Furthermore, the lifting mechanism 4 is not limited to a configuration that moves the sheet stacking platform 21 linearly in the up-down direction D1, and may lift and lower the sheet stacking platform 21, for example, by rotating the sheet stacking platform 21 around one end (left end) of the sheet stacking platform 21 in the left-right direction D3 as a fulcrum.

[0040] The set sensor 5 detects whether or not the sheet Sh1 is set on the sheet stacking tray 21. Here, the set sensor 5 detects whether the sheet Sh1 is set correctly, that is, whether the sheet Sh1 is placed on the sheet stacking tray 21 in a state where it can be conveyed by the conveyance mechanism 3. When the sheet Sh1 is set correctly on the sheet stacking tray 21, the set sensor 5 outputs an electrical signal indicating the detection result, that is, whether the sheet Sh1 is set correctly, to the control unit 15. Therefore, the set sensor 5 does not detect that the sheet Sh1 is set just because the sheet Sh1 is on the sheet stacking tray 21. The set sensor 5 detects that the sheet Sh1 is set only when the leading edge (left edge) of the sheet Sh1 is inserted into the intake port 30, as shown in FIG. 3 .

[0041] As an example, in this embodiment, as shown in FIGS. 3 and 4, the set sensor 5 is disposed facing upward at the left end of the sheet stacking tray 21, which is located inside (left side of) the inlet 30 and in the center of the front-to-rear direction D2. This allows the set sensor 5 to detect the presence or absence of sheet Sh1 above the left end of the sheet stacking tray 21. When the leading edge (left end) of sheet Sh1 is present above the left end of the sheet stacking tray 21, the set sensor 5 outputs an electrical signal indicating that sheet Sh1 has been properly set. As an example, the set sensor 5 is a non-contact sensor that utilizes reflection of light, ultrasonic waves, or the like. That is, the set sensor 5 has, for example, a light-emitting element and a light-receiving element, and detects the presence of sheet Sh1 when light emitted upward from the light-emitting element is reflected by the sheet Sh1 located directly above the set sensor 5 and received by the light-receiving element. As a result, if the light receiving element does not receive reflected light, the set sensor 5 outputs an electrical signal indicating that the sheet Sh1 is not set correctly, and if the light receiving element receives reflected light, the set sensor 5 outputs an electrical signal indicating that the sheet Sh1 is set correctly.

[0042] As shown in FIGS. 3 and 4, the jump-up sensor 6 detects the jump-up of the sheet Sh1 during conveyance in a monitoring area R1 above the inlet 30. The monitoring area R1 here is an area in which the jump-up sensor 6 monitors the presence or absence of the sheet Sh1, and in this embodiment, as shown in FIG. 4, the monitoring area R1 is set above the inlet 30 over substantially the entire length of the inlet 30 in the front-to-rear direction D2 (the shaded area in FIG. 4). The "jump-up" of the sheet Sh1 here refers to an abnormal state of the sheet Sh1, including the sheet Sh1 being rolled up, bent, or lifted in a direction away from the sheet stacking tray 21 (upward). In other words, the jump-up sensor 6 detects that the sheet Sh1 is in an abnormal state when at least a portion of the sheet Sh1 on the sheet stacking tray 21 is jumping up. For example, when a plurality of sheets Sh1 on the sheet stacking tray 21 are fastened with a fastener such as a staple, and the conveying mechanism 3 attempts to convey one of the plurality of sheets Sh1, the sheet Sh1 jumps up, and the jump-up sensor 6 detects the jump-up sheet Sh1 as the jump-up sheet Sh1 enters the monitoring area R1, and detects the jump-up of the sheet Sh1 during conveyance.

[0043] As an example, in this embodiment, the jump-up sensor 6 includes a light-emitting unit 61 and a light-receiving unit 62 disposed above the intake port 30 on both sides in the front-rear direction D2, as shown in FIG. 4 . The light-emitting unit 61 and the light-receiving unit 62 are disposed facing each other inside sidewalls facing each other in the front-rear direction D2. The jump-up sensor 6 is a non-contact, light-transmitting sensor with a monitoring area R1 defined by the area between the light-emitting unit 61 and the light-receiving unit 62. That is, the jump-up sensor 6 detects a detection target X1 (see FIG. 5 ) within the monitoring area R1 when at least a portion of the light from the light-emitting element included in the light-emitting unit 61 is blocked before being received by the light-receiving element included in the light-receiving unit 62. The detection target X1 here is an object whose presence within the monitoring area R1 is to be detected, such as the (jumped-up) seat Sh1 or a part of the user's body.

[0044] As a result, the jump-up sensor 6 detects the detection object X1 in the monitoring area R1 based on the output of the light-receiving unit 62, which changes depending on the amount of light emitted from the light-emitting unit 61 and incident on the light-receiving unit 62 through the monitoring area R1. The jump-up sensor 6 outputs an electrical signal output by the light-receiving unit 62 to the control unit 15. In short, when the amount of light from the light-emitting unit 61 received by the light-receiving unit 62 decreases and the output of the light-receiving unit 62 decreases, the control unit 15 can determine that the detection object X1 is present in the monitoring area R1. On the other hand, if the amount of light from the light-emitting unit 61 received by the light-receiving unit 62 does not decrease, the control unit 15 can determine that the detection object X1 is not present in the monitoring area R1.

[0045] The transport control unit 24 controls the transport mechanism 3. The transport control unit 24 starts transport of the sheet Sh1 when a predetermined transport start operation is performed with the sheet Sh1 properly set on the sheet stacking tray 21. That is, the transport control unit 24 controls the transport mechanism 3 based on the detection result of the set sensor 5, and enables transport of the sheet Sh1 only when the set sensor 5 detects that the sheet Sh1 is properly set on the sheet stacking tray 21. Specifically, the transport control unit 24 enters a state in which it is possible to accept a transport start operation. In this state, when the user performs a transport start operation on the operation display unit 14, which means, for example, the start of image processing (here, image reading), the transport control unit 24 controls the transport mechanism 3 to start transport of the sheet Sh1. On the other hand, if the set sensor 5 does not detect that the sheet Sh1 is properly set, the transport control unit 24 does not accept the transport start operation and does not start transport of the sheet Sh1.

[0046] Furthermore, in this embodiment, when the jump sensor 6 detects that the sheet Sh1 has jumped up during conveyance of the sheet Sh1, the conveyance control unit 24 controls the conveyance mechanism 3 to stop conveyance of the sheet Sh1. That is, the conveyance control unit 24 controls the conveyance mechanism 3 based on the detection result of the jump sensor 6. When the jump sensor 6 detects that the sheet Sh1 has jumped up during conveyance of the sheet Sh1, the conveyance control unit 24 makes an emergency stop of the conveyance mechanism 3. Then, after the conveyance control unit 24 makes an emergency stop of the conveyance mechanism 3, when the jump sensor 6 no longer detects that the sheet Sh1 has jumped up, for example, because the sheet Sh1 whose jumping up was detected is removed, the conveyance control unit 24 resumes conveyance of the sheet Sh1. Here, it is preferable that the conveyance control unit 24 resumes conveyance of the sheet Sh1 when a predetermined conveyance resumption operation is performed. With this configuration, when an abnormal state (jumping up) of the sheet Sh1 is detected during conveyance of the sheet Sh1, the conveyance of the sheet Sh1 can be automatically stopped. As a result, it is possible to prevent the abnormal sheet Sh1 from being forcibly conveyed, which leads to protection of the sheet Sh1 and the sheet conveying device 2.

[0047] The lift control unit 23 controls the lift mechanism 4. When a predetermined lift start operation is performed, the lift control unit 23 starts lifting or lowering the sheet stacking table 21. Specifically, when the user performs a lift start operation on the operation display unit 14, which operation means, for example, the start of image processing (here, image reading), the lift control unit 23 controls the lift mechanism 4 to lift the sheet stacking table 21 to a position where the transport roller 311 contacts the upper surface of the sheet Sh1 placed on the sheet stacking table 21 from above.

[0048] Furthermore, in this embodiment, when the jump sensor 6 detects the detection object X1 while the sheet stacking platform 21 is being raised, the lift control unit 23 controls the lifting mechanism 4 to stop the lifting of the sheet stacking platform 21. That is, the lift control unit 23 controls the lifting mechanism 4 based on the detection result of the jump sensor 6, and when the jump sensor 6 detects a foreign object (detection object X1) such as a user's finger while the sheet stacking platform 21 is being raised, the lift control unit 23 makes an emergency stop of the lifting mechanism 4. Then, after the lift control unit 23 makes an emergency stop of the lifting mechanism 4, when the detected foreign object (detection object X1) is no longer detected by the jump sensor 6, for example, because the detected foreign object (detection object X1) is removed, the lift control unit 23 resumes the lifting of the sheet stacking platform 21. Here, it is preferable that the lift control unit 23 resumes the lifting of the sheet stacking platform 21 when a predetermined lifting / lowering restart operation is performed. According to this configuration, if a foreign object (detection object X1) is detected while the sheet stacking tray 21 is being raised, the raising of the sheet stacking tray 21 can be automatically stopped. As a result, it is possible to prevent foreign objects such as the user's fingers from being caught in the sheet stacking tray 21, which leads to the protection of the user and the sheet conveying device 2.

[0049] Incidentally, a known technology related to this type of sheet conveying device 2 is a sheet conveying (feeding) device that includes a sheet stacking tray (sheet stacking means) on which sheets are stacked, and a conveying mechanism (sheet taking-in means and separation feeding means) that takes in the sheets stacked on the sheet stacking tray and conveys (feeds) the sheets one by one.

[0050] A sheet transport device according to the related art further includes a jump sensor (sheet abnormality detection means) that detects a sheet jumping up on the sheet stacking table. The jump sensor has a light-emitting unit that emits light and a light-receiving unit that receives the light emitted by the light-emitting unit, and detects an obstacle when an obstacle blocks the optical path of the light emitted from the light-emitting unit until it reaches the light-receiving unit. This allows the sheet transport device to detect a jumping up of a sheet when taking in a sheet and stop conveying the sheet, and to detect a hand or other object as an obstacle when raising the sheet stacking table and stop raising the sheet stacking table to prevent the hand or other object from getting caught.

[0051] However, in the configuration of the related technology described above, the jump sensor detects obstacles in the optical path from when light is emitted from the light-emitting element to when it reaches the light-receiving element. For example, if a Z-folded document (a sheet folded in a Z shape) is detected when the sheet stacking tray is being raised, the raising of the sheet stacking tray may be stopped.

[0052] In contrast to this, in this embodiment, the sheet conveying device 2 and the image processing device 10 that are less likely to cause erroneous detection are realized by the configuration described below.

[0053] That is, the sheet transport device 2 according to this embodiment includes a sheet stacking tray 21, a sheet discharge tray 22, a transport mechanism 3, a lifting mechanism 4, a jump sensor 6, and a sensitivity setting unit 25. The transport mechanism 3 takes in a sheet Sh1 placed on the sheet stacking tray 21 through an inlet 30 and transports it onto the sheet discharge tray 22 via an execution position P1 where image processing is performed by an image processing unit. The lifting mechanism 4 raises and lowers the sheet stacking tray 21. The jump sensor 6 monitors an area R1 above the inlet 30 and detects a detection target X1 in the monitoring area R1 based on the output of the light-receiving unit 62, which varies depending on the amount of light emitted from the light-emitting unit 61 and incident on the light-receiving unit 62 through the monitoring area R1. The sensitivity setting unit 25 changes the sensitivity of the jump sensor 6 when the sheet Sh1 is taken in through the inlet 30 and when the sheet stacking tray 21 is raised. In this embodiment, the sensitivity setting unit 25, which is a component of the sheet conveying device 2, is provided in the control unit 15 as one of its functions.

[0054] According to the above-described configuration, the sheet conveying device 2 according to this embodiment and the image processing device 10 including the sheet conveying device 2 have the advantage of being less likely to cause false detection by the jump-up sensor 6. That is, since the sensitivity of the jump-up sensor 6 differs when the sheet Sh1 is taken in from the inlet 30 and when the sheet stacking tray 21 is raised, the jump-up sensor 6 can be operated at an appropriate sensitivity for each scene. For example, by increasing the sensitivity when the sheet Sh1 is taken in from the inlet 30, it is possible to reliably detect the jumping up of the sheet Sh1. On the other hand, by decreasing the sensitivity when the sheet stacking tray 21 is raised, it is possible to eliminate false detection of a Z-folded document while reliably detecting the user's fingers and preventing the fingers from getting caught.

[0055] Moreover, although the jump sensor 6 is originally a sensor for detecting the jumping up of the sheet Sh1, it is also used to detect foreign objects such as the user's fingers when the sheet stacking tray 21 is raised. Therefore, with the above configuration, it is possible to prevent foreign objects from getting caught in the sheet stacking tray 21 when the sheet stacking tray 21 is raised, while suppressing an increase in the number of components.

[0056] 5, the jump sensor 6 has a light-emitting unit 61 and a light-receiving unit 62 that are arranged opposite each other with a monitoring area R1 in between. Here, the output of the light-receiving unit 62 changes continuously according to the amount of light (received by the light-receiving unit 62). In other words, the output of the light-receiving unit 62 is not a binary on / off output, but an analog output that changes continuously in conjunction with the amount of light received, so that the output increases as the amount of light received increases.

[0057] In this way, the output of the light receiving unit 62 changes continuously depending on the amount of received light, which enables the jump-up sensor 6 to detect various detection objects X1. That is, the output of the light receiving unit 62 changes depending on the amount of light emitted from the light emitting unit 61 and reaching the light receiving unit 62, in other words, the amount of light blocked by the detection object X1 in the monitoring area R1. This makes it possible for the same jump-up sensor 6 to detect both a detection object X1 whose amount of received light does not decrease significantly, such as a sheet Sh1, and a detection object X1 whose amount of received light decreases significantly, such as a user's finger.

[0058] In this embodiment in particular, the light receiving unit 62 includes a phototransistor 621. That is, in the light receiving unit 62, the current flowing through the phototransistor 621 continuously changes in accordance with the amount of received light. As the amount of received light decreases, the current flowing through the phototransistor 621 also decreases. This configuration makes it easy to achieve a configuration in which the output of the light receiving unit 62 changes in accordance with the amount of received light.

[0059] 5 , the control unit 15 acquires the output of the phototransistor 621 using the AD converter 152. Specifically, the output (current) of the phototransistor 621 is converted into a voltage by inputting the voltage across the resistor 622 connected in series with the phototransistor 621 to the AD converter 152, and the control unit 15 recognizes the output of the phototransistor 621 as an analog value. In other words, the control unit 15 can acquire the output of the light receiving unit 62, which changes continuously, using the analog signal input to the AD converter 152.

[0060] Furthermore, in this embodiment, the light-emitting unit 61 includes a light-emitting diode 611. That is, the light-emitting unit 61 continuously changes the amount of light emitted in accordance with the current supplied to the light-emitting diode 611. As the current supplied to the light-emitting diode 611 increases, the amount of light emitted from the light-emitting unit 61 also increases. This configuration makes it easy to change the amount of light from the light-emitting unit 61.

[0061] 5, in this embodiment, the control unit 15 is configured to be able to adjust the current supplied to the light-emitting diode 611 using the output of the DA converter 151. In other words, the analog signal output from the DA converter 151 can be used to continuously change the current supplied to the light-emitting diode 611, thereby continuously changing the amount of light emitted from the light-emitting unit 61.

[0062] Here, even when the detection object X1 is present in the monitoring area R1, the amount of transmitted light is not constant but varies depending on the detection object X1. Fig. 6 is a graph illustrating the correspondence relationship between the output (amount of light emitted) of the light-emitting unit 61 and the output (voltage across resistor 622) of the light-receiving unit 62 when thin paper, regular paper, thick paper, or a (user's) finger is present in the monitoring area R1 as the detection object X1. Here, thin paper, regular paper, and thick paper are all sheets Sh1, with thin paper being thinner than regular paper and therefore having high light transmittance, and thick paper being thicker than regular paper and therefore having low light transmittance.

[0063] 6, the horizontal axis represents the output of the light-emitting unit 61 and the vertical axis represents the output of the light-receiving unit 62, and graphs G1, G2, G3, G4, G5, and G6 show graphs for when thin paper is not present, plain paper, cardboard, and fingers, respectively. If the output of the light-emitting unit 61 is the same, it is assumed that the amount of light transmitted through the monitoring area R1 decreases in the order of thin paper, plain paper, cardboard, and fingers.

[0064] If the output of the light-emitting unit 61 is the same, the output of the light-receiving unit 62, which converts the current flowing through the phototransistor 621 into a voltage, changes depending on the amount of light transmitted through the monitoring area R1. That is, the control unit 15 can estimate the amount of light transmitted through the monitoring area R1 from the voltage input to the AD converter 152. Since the amount of light transmitted through the monitoring area R1 changes depending on the detection object X1 present in the monitoring area R1, as shown in FIG. 6, if the output of the light-emitting unit 61 is the same, the output of the light-receiving unit 62 decreases in the order of thin paper, regular paper, thick paper, and finger.

[0065] Also, if the detection target object X1 existing in the monitoring area R1 is the same, the light transmittance in the monitoring area R1 is the same. Therefore, the output of the light receiving unit 62 obtained by converting the current flowing through the phototransistor 621 into a voltage changes according to the output of the light emitting unit 61. That is, as shown in FIG. 6, if the detection target object X1 is the same, the larger the output of the light emitting unit 61, the larger the output of the light receiving unit 62 on the vertical axis.

[0066] Here, the sensitivity setting unit 25 changes the magnitude of the light output of the light emitting unit 61 when the sheet Sh1 is taken in from the intake port 30 and when the sheet loading table 21 is raised. Specifically, when the upper limit value (maximum value) of the light output of the light emitting unit 61 is the value Vi3, the light output of the light emitting unit 61 is set to the value Vi2 (<Vi3) when the sheet loading table 21 is raised, and the light output of the light emitting unit 61 is set to an even smaller value Vi1 (<Vi2) when the sheet Sh1 is taken in from the intake port 30. Here, the light output of the light emitting unit 61 when the sheet Sh1 is taken in from the intake port 30 is the value Vi1 when the output of the light receiving unit 62 when there is no detection target object X1 in the monitoring area R1 saturates (value Vr4).

[0067] That is, when the sheet Sh1 is taken in from the intake port 30, the light output of the light emitting unit 61 is suppressed to a small value so that the detection target object X1 can be detected even if it is thin paper, and the output of the light receiving unit 62 does not saturate even when the detection target object X1 is thin paper. In short, since thin paper has a large light transmittance, if the light output of the light emitting unit 61 is too large, the output of the light receiving unit 62 saturates in a state where thin paper exists in the monitoring area R1, and there is no output difference between the state where there is no detection target object X1 in the monitoring area R1 and the light receiving unit 62, making it impossible to discriminate the presence or absence of thin paper. Therefore, when the sheet Sh1 is taken in from the intake port 30, the light output of the light emitting unit 61 is suppressed to a small value to enable discrimination of the bounce of the sheet Sh1 including thin paper in the monitoring area R1.

[0068] On the other hand, when the sheet loading table 21 is raised, the light output of the light emitting unit 61 is increased so that it is possible to determine whether the detection target X1 is cardboard or a finger, and the output difference of the light receiving unit 62 is increased by the detection target X1. In short, when the sheet loading table 21 is raised, the light output of the light emitting unit 61 is increased, making it easier to avoid false detection of the sheet Sh1 including cardboard in the monitoring area R1.

[0069] Also, the sensitivity setting unit 25 changes the sensitivity of the jump-up sensor 6 by changing the determination threshold for detecting the detection target X1 with respect to the output of the light receiving unit 62 when the sheet Sh1 is taken in from the intake port 30 and when the sheet loading table 21 is raised. Specifically, when the upper limit value (saturation value) of the output of the light receiving unit 62 is set as the value Vr4, the determination threshold Vth1 (<Vr4) is set when the sheet Sh1 is taken in from the intake port 30, and a smaller determination threshold Vth2 (<Vth1) is set when the sheet loading table 21 is raised. Here, as an example, the determination threshold Vth1 when the sheet Sh1 is taken in from the intake port 30 is the intermediate value between the value Vr4 of the output of the light receiving unit 62 when there is no detection target X1 in the monitoring area R1 and the value Vr3 of the output of the light receiving unit 62 when thin paper exists as the detection target X1 in the monitoring area R1. Similarly, the determination threshold Vth2 when the sheet loading table 21 is raised is the intermediate value between the value Vr2 of the output of the light receiving unit 62 when thick paper exists as the detection target X1 in the monitoring area R1 and the value Vr1 of the output of the light receiving unit 62 when a finger exists as the detection target X1 in the monitoring area R1.

[0070] That is, when the sheet Sh1 is taken in from the intake port 30, the determination threshold Vth1 for detecting the detection target X1 with respect to the output of the light receiving unit 62 is set higher so that the detection target X1 can be detected even if it is thin paper, and the jump-up sensor 6 is made highly sensitive. That is, when the sheet Sh1 is taken in from the intake port 30, the jump-up sensor 6 is made highly sensitive to enable discrimination of the jumping up of the sheet Sh1 including thin paper in the monitoring area R1.

[0071] On the other hand, when the sheet stacking tray 21 is raised, in order to prevent the detection object X1 from being erroneously detected as cardboard (for example, as a finger), the judgment threshold Vth2 for detecting the detection object X1 is set low relative to the output of the light receiving unit 62, and the jump-up sensor 6 is made low-sensitive. In short, when the sheet stacking tray 21 is raised, the jump-up sensor 6 is made low-sensitive, making it easier to avoid erroneous detection of sheets Sh1 including cardboard in the monitoring area R1.

[0072] When sheet Sh1 is taken in through the intake port 30, if a detection object X1 present in the monitoring area R1 is detected, the control unit 15 determines that a jumping up of sheet Sh1 has been detected, and causes the conveying control unit 24 to stop the taking in of sheet Sh1 from the intake port 30 (the conveying of sheet Sh1).

[0073] On the other hand, when the detection object X1 present in the monitoring area R1 is detected while the sheet stacking tray 21 is being raised, the control unit 15 determines that a foreign object (such as a user's finger) has been detected, and causes the lifting control unit 23 to stop the raising of the sheet stacking tray 21. In this case, even if a specific operation such as pressing the start key on the operation display unit 14 is performed, it is preferable that the raising operation of the sheet stacking tray 21 not be resumed as long as the detection object X1 present in the monitoring area R1 has been detected.

[0074] According to the configuration described above, it is possible to distinguish between sheet Sh1 and a foreign object such as a finger from the output value of the light receiving unit 62 in the jump sensor 6, and if it is sheet Sh1 present in the monitoring area R1, the sheet stacking tray 21 continues to rise, etc., thereby preventing the operation of the sheet conveying device 2 from being stopped more than necessary.

[0075] Incidentally, as a reference example, even if the detection object X1 present in the monitoring area R1 is detected, it is conceivable that the lifting operation of the sheet stacking tray 21 can be resumed by performing a specific operation such as pressing the start key on the operation display unit 14. However, in this reference example, the detection result of the jump-up sensor 6 is ignored and the sheet stacking tray 21 is lifted, which increases the risk of fingers or the like getting caught.

[0076] [3] Variation Multiple components included in the image processing device 10 may be distributed across multiple housings. For example, the lift control unit 23, which is a component of the sheet conveying device 2, is not limited to being realized as one function of the control unit 15, and may be provided in a housing separate from the control unit 15. In other words, the sheet conveying device 2 does not have to be integrated with the image processing device 10, and at least a part of the sheet conveying device 2 may be provided in a housing separate from the image processing device 10.

[0077] Furthermore, the sheets conveyed by the sheet conveying device 2 may be sheets on which an image is to be formed by the image forming unit 12, that is, sheets supplied by the paper feeding unit 13. In this case, for example, the manual feed tray of the paper feeding unit 13 corresponds to the sheet stacking table of the sheet conveying device 2, and the paper discharge tray 123 of the image forming unit 12 corresponds to the sheet discharge table of the sheet conveying device 2.

[0078] Furthermore, the arrangement and detection method of the set sensor 5 and the jump-up sensor 6 are not limited to the configuration described in the first embodiment and can be changed as appropriate. For example, the jump-up sensor 6 may be a reflective sensor that utilizes the reflection of light.

[0079] Furthermore, the transport control unit 24 is not limited to a configuration that stops the transport of the sheet Sh1 when the jump-up sensor 6 detects that the sheet Sh1 has jumped up during transport of the sheet Sh1. For example, the transport control unit 24 may reduce the transport speed of the sheet Sh1 when the jump-up sensor 6 detects that the sheet Sh1 has jumped up during transport of the sheet Sh1. Furthermore, it is not essential that the lift control unit 23 causes the sheet stacking tray 21 to wait at the initial position that is above the lower limit position of the lift range of the sheet stacking tray 21 after transport of the sheet Sh1. For example, the lift control unit 23 may cause the sheet stacking tray 21 to wait at the position after it has been lowered.

[0080] [Appendix to the invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0081] <Appendix 1> A seat loading platform; a sheet discharge tray; a conveying mechanism that takes in a sheet placed on the sheet stacking table through an inlet and conveys the sheet onto the sheet discharge table through an execution position where image processing is performed by an image processing unit; a lifting mechanism for lifting and lowering the sheet stacking table; a jump sensor that monitors an area above the intake port and detects an object to be detected in the monitoring area based on an output of the light receiving unit that changes in accordance with the amount of light emitted from the light emitting unit and incident on the light receiving unit through the monitoring area; a sensitivity setting unit that changes the sensitivity of the jump-up sensor when the sheet is taken in through the take-in opening and when the sheet stacking table is raised, Sheet transport device.

[0082] <Appendix 2> The output of the light receiving unit changes continuously according to the amount of light. 2. The sheet conveying device according to claim 1.

[0083] <Appendix 3> The light receiving unit includes a phototransistor. 3. The sheet conveying device according to claim 1 or 2.

[0084] <Appendix 4> the sensitivity setting unit changes the magnitude of the light output of the light emitting unit when the sheet is taken in through the inlet and when the sheet stacking table is raised. 4. The sheet conveying device according to any one of claims 1 to 3.

[0085] <Appendix 5> the sensitivity setting unit changes the sensitivity of the jump-up sensor by changing a determination threshold for detecting the detection object with respect to the output of the light receiving unit when the sheet is taken in through the take-in opening and when the sheet stacking table is raised. 5. A sheet conveying device according to any one of appendices 1 to 4.

[0086] <Appendix 6> A sheet conveying device according to any one of Supplementary Notes 1 to 5; the image processing unit performs at least one of reading an image and forming an image on the sheet; Image processing device. [Explanation of symbols]

[0087] 2. Sheet transport device 3. Transport mechanism 4 Lifting mechanism 6 Jump Sensor 10 Image processing device 11 Image reading unit (image processing unit) 12 Image forming unit (image processing unit) 21 Seat loading platform 22 Sheet discharge stand 25 Sensitivity setting section 30 Intake 61 Light-emitting part 62 Light receiving part 621 Phototransistor P1 execution position R1 monitoring area Sh1 sheet Vth1, Vth2 judgment threshold X1 Detection target

Claims

1. A sheet loading platform; a sheet discharge tray; a conveying mechanism that takes in a sheet placed on the sheet stacking table through an inlet and conveys the sheet onto the sheet discharge table through an execution position where image processing is performed by an image processing unit; a lifting mechanism for lifting and lowering the sheet stacking table; a jump sensor that monitors an area above the intake port and detects an object to be detected in the monitoring area based on an output of the light receiving unit that changes in accordance with the amount of light emitted from the light emitting unit and incident on the light receiving unit through the monitoring area; a sensitivity setting unit that changes the sensitivity of the jump-up sensor when the sheet is taken in through the take-in opening and when the sheet stacking table is raised, Sheet transport device.

2. The output of the light receiving unit changes continuously according to the amount of light. The sheet transport device according to claim 1 .

3. The light receiving unit includes a phototransistor.

3. The sheet conveying device according to claim 1 or 2.

4. the sensitivity setting unit changes the magnitude of the light output of the light emitting unit when the sheet is taken in through the inlet and when the sheet stacking table is raised.

3. The sheet conveying device according to claim 1 or 2.

5. the sensitivity setting unit changes the sensitivity of the jump-up sensor by changing a determination threshold for detecting the detection object with respect to the output of the light receiving unit when the sheet is taken in through the take-in opening and when the sheet stacking table is raised.

3. The sheet conveying device according to claim 1 or 2.

6. The sheet conveying device according to claim 1 or 2; the image processing unit performs at least one of reading an image and forming an image on the sheet; Image processing device.

Images