Feeding device and image forming apparatus

Abstract

To prevent a failure from occurring in which, even when a sheet is placed on a placement part, it is erroneously detected that a sheet is not placed.SOLUTION: A feeding device feeds a manuscript D(sheet) in a predetermined feeding direction, and a manuscript placement part 60 (placement part) on which the manuscript D can be placed is provided. Also, it includes: a filler 75 which is pushed by a tip of the manuscript D on the feeding direction downstream side placed on the manuscript placement part 60 and rotates to a pushing position from a reference position around a support shaft 75a; and a first detection sensor S1 for detecting the rotation of the filler 75 from the reference position (or pushing position) to the pushing position (or reference position). Then, at the manuscript placement part 60, a second sensor S2 is provided for detecting the state where the manuscript D is placed on the manuscript placement part 60.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a feeding device such as a document transporting device that feeds sheets such as documents, and to an image forming apparatus including the feeding device, such as a copying machine, a printer, a facsimile machine, or a multifunction machine or a printing machine including the feeding device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines, printers, and printing machines, document transport devices have been widely used as feeding devices that feed documents as sheets (see, for example, Patent Document 1).

[0003] On the other hand, Patent Document 1 discloses a technique in which, in an original transport device (ADF), when an original (sheet) is placed on an original table (mounting section), a set filler (filler) is pushed by the paper and rotates from an original non-set position (reference position) to an original set position (pushing position), and the rotated state is optically detected by an original set sensor. Then, when the original set sensor detects the setting of the original in this way, this triggers the start of the feeding operation of the original transport device. Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology, when a sheet is placed on the placement section (original table), the filler is pushed by the sheet and rotates from the reference position to the pushing position, and after the rotated state is detected by the detection sensor, the sheet is sometimes pushed back slightly by the filler in a direction away from the filler. In such a case, the filler rotates from the pushing position to the reference position, and it is erroneously detected that no sheet is placed on the placement section, and normal feeding operation is not started.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide a feeding device and an image forming apparatus that are less likely to cause the problem of erroneously detecting that no sheet is placed on the placement section even when a sheet is actually placed on the placement section. [Means for solving the problem]

[0006] The feeding device of the present invention is a feeding device that feeds a sheet in a predetermined feeding direction, and includes a placement section on which a sheet can be placed, a filler that is pushed by a downstream leading end of a sheet placed on the placement section in the feeding direction and rotates from a reference position to a pushing position around a support shaft, and a first detection sensor that detects the rotation of the filler from the reference position or the pushing position to the pushing position or the reference position, and the placement section includes a second detection sensor that detects a state in which a sheet is placed on the placement section. When the first detection sensor detects the rotation of the filler from the reference position to the pushing position and then detects the rotation of the filler from the pushing position to the reference position, and the second detection sensor continues to detect the placement of a sheet on the placement section during that time, the sheet is considered to be placed on the placement section and a feeding operation is started. It is something. Effect of the Invention

[0007] According to the present invention, it is possible to provide a feeding device and an image forming apparatus which are less likely to cause the problem of erroneously detecting that a sheet is not placed on the placement section even though a sheet is actually placed on the placement section. [Brief description of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram illustrating a configuration of a document transport device. [Diagram 3] FIG. 2 is an enlarged view showing a main part of the document transport device. [Figure 4] FIG. 2 is a top view showing a main part of the document transport device. [Diagram 5] 5 is a flowchart showing an example of control performed in the document transport device. [Figure 6] 13 is a flowchart showing control performed in a document transport device according to a first modified example. [Figure 7]FIG. 11 is an enlarged view showing a main part of a document transport device serving as a second modified example. [Figure 8] 8 is a top view showing a main part of the document transport device of FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and the duplicated description will be appropriately simplified or omitted.

[0010] First, the overall configuration and operation of an image forming apparatus 1 will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a copier as an image forming apparatus, 3 denotes an exposure unit that irradiates a photosensitive drum 5 with exposure light L based on image information read by an image reading unit 2 and 80, 4 denotes an image creating unit that forms a toner image (image) on the photosensitive drum 5, and 9 denotes a transfer unit (image forming unit) that transfers the toner image formed on the photosensitive drum 5 to paper P. Further, reference numeral 10 denotes an original document transport device (ADF) serving as a feeding device that feeds an original document D (sheet) set on an original document placing section 60 and discharges it to an original document discharge section 61, reference numerals 12 to 14 denote a paper feed section in which paper paper P is stored, and reference numeral 17 denotes a registration roller (timing roller) that transports paper paper P toward the transfer section 9. In addition, reference numeral 18 denotes a first image reading unit that optically reads image information on the front side of the original D, 20 denotes a fixing device that fixes the toner image (unfixed image) carried on the paper P, 31 denotes a paper output tray on which the paper P discharged from the image forming apparatus main body 1 is loaded, and 80 denotes a second image reading unit that optically reads image information on the back side of the original D.

[0011] With reference to FIG. 1, the operation of the image forming apparatus main body 1 during normal image formation will be described. First, in the document transport device 10, the document D as a sheet is transported (fed) from the document loading section 60 as a loading section, and passes the position of the first image reading section 18. At this time, the first image reading section 18 optically reads image information on the front side of the document D passing above it. The optical image information read by the first image reading unit 18 is converted into an electrical signal and then transmitted to the exposure unit 3 (writing unit). The exposure unit 3 then emits exposure light L, such as a laser beam, based on the image information of the electrical signal toward the photoconductor drum 5 of the imaging unit 4.

[0012] Meanwhile, in the image creating unit 4, the photosensitive drum 5 rotates clockwise in the figure, and after going through a predetermined image creating process (charging process, exposure process, and development process), an image (toner image) corresponding to the image information is formed on the photosensitive drum 5. Thereafter, the image formed on the photosensitive drum 5 is transferred to the transfer section 9 onto the paper P conveyed by the registration rollers 17 .

[0013] On the other hand, the paper P transported to the transfer unit 9 (image forming unit) operates as follows. First, one of the multiple paper feed units 12-14 of the image forming apparatus main body 1 is automatically or manually selected (for example, assume that the topmost paper feed unit 12 in the apparatus main body 1 is selected). Then, the topmost sheet of paper P stored in the paper feed unit 12 is fed by the paper feed mechanism 52 (comprised of a feed roller, a pickup roller, a backup roller, etc.) and conveyed toward the conveying path. Thereafter, the paper P passes through the conveying path on which multiple conveying rollers are arranged, and reaches the position of the registration rollers 17.

[0014] The paper P that has reached the position of the registration rollers 17 is transported toward a transfer unit 9 (image forming unit) in time for alignment with the image formed on the photosensitive drum 5. Then, after the transfer process, the paper P passes through the position of the transfer unit 9, and then reaches the fixing device 20 via a transport path. The paper P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, and the toner image is fixed to the paper P by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22 (the fixing process). After the fixing process, the paper P with the fixed toner image is sent out from between the fixing roller 21 and the pressure roller 22 (the fixing nip), and then discharged from the image forming apparatus main body 1 and stacked on the paper output tray 31 as an output image. In this way, a series of image forming processes is completed.

[0015] When forming an image based on the image of the back side of the document D in addition to the front side, when the document D passes through the position of the second image reading unit 80 via the position of the first image reading unit 18 in the document transport device 10, the image information of the back side of the document D passing underneath is optically read by the second image reading unit 80. Then, similar to the image formation process based on the image of the front side, the optical image information read by the second image reading unit 80 is transmitted to the exposure unit 3, and the image formation process based on that is performed.

[0016] Next, the configuration and operation of the document transport device 10 serving as a feeding device will be described in detail with reference to FIG. As shown in FIG. 2, the document transport device 10 is composed of a document placement section 60 (placement section), a first image reading section 18, a second image reading section 80, a document discharge section 61 (paper discharge tray), a pickup roller 62, a feed roller 63, a reverse roller 64, multiple transport roller pairs 65-69, a discharge roller pair 70 (paper discharge roller pair), size detection sensors S4-S7, document detection sensors S8-S13, etc.

[0017] Here, the document placement section 60 as a placement section has an open space formed at the top, and is configured so that a user can place the document D from above with the front side facing upward (configured so that a stack of multiple documents D can be stacked). Although not shown, the document placement section 60 is provided with a pair of side fences for determining the position of the placed document D in the width direction (the direction perpendicular to the feeding direction, the direction perpendicular to the paper surface in Figs. 1 to 3, and the vertical direction in Fig. 4). The document discharge section 61 is disposed below the document loading section 60, and is configured so that the document D is discharged and loaded after the image has been read by the image reading sections 18, 80 (configured so that multiple sheets of the document D can be stacked).

[0018] Further, on the transport path from the document placement section 60 to the document discharge section 61, there are provided, in order from the upstream side in the transport direction, a pickup roller 62, a feed roller 63, a reverse roller 64, a first transport roller pair 65 (abutting roller pair), a second transport roller pair 66, a third transport roller pair 67, a fourth transport roller pair 68, a fifth transport roller pair 69, and a discharge roller pair 70. These roller members 62 to 70 function as transport means that transport the document D placed on the document placement section 60 toward the positions of the first image reading section 18 and the second image reading section 80, and transport the document D after image reading toward the document discharge section 61.

[0019] In addition, in the transport path formed by these roller members 62 to 70, as shown in FIG. 2, a number of guide plates for guiding the transport of the original D are installed approximately parallel to each other on the side facing the front surface of the original D and the side facing the back surface of the original D.

[0020] Here, the multiple transport roller pairs 65-69 (particularly the three transport roller pairs 67-69 related to the reading accuracy at the positions of the first image reading unit 18 and the second image reading unit 80) transport the original D at a predetermined transport speed (constant speed) at the positions of the first image reading unit 18 and the second image reading unit 80. The first image reading unit 18 is disposed so as to face the front side of the original D on the transport path between the third transport roller pair 67 and the fourth transport roller pair 68, and the second image reading unit 80 is disposed so as to face the back side of the original D on the transport path between the fourth transport roller pair 68 and the fifth transport roller pair 69. The discharge roller pair 70 is disposed at the position of the document discharge port downstream in the transport direction with respect to a fifth conveyor roller pair 69 that is located on the most downstream side in the transport direction among the multiple conveyor roller pairs 65 to 69. Then, the document D after the image has been read at the position of the first image reading unit 18 or the second image reading unit 80 is conveyed by the discharge roller pair 70 and discharged (stacked) toward the document discharge unit 61.

[0021] 2, the document placement unit 60 has a plurality of document detection sensors S8 to S13 installed along the transport path of the document D. These document detection sensors S8 to S13 are reflective photosensors that detect the presence or absence of a jam of the document D on the transport path and control the transport timing to the image reading units 18, 80 and the reading timing of the image reading units 18, 80. 2, the document placement section 60 has a plurality of size detection sensors S4 to S7 arranged in parallel along the feeding direction on the upstream side in the feeding direction (the right side in FIG. 2, which is a fixed placement section portion other than the lift-and-lower placement section 60a). These size detection sensors S4 to S7 are reflective photosensors that optically detect the rear end (the end portion on the upstream side in the feeding direction) of the document D placed on the document placement section 60 to detect the size of the document D.

[0022] The basic operation of the document transport device 10 thus configured will now be described. First, when the document D (at least the document D with an image formed on its front surface) is loaded on the document placement section 60 with its front surface facing up so that its leading edge (leading edge in the feeding direction) hits the reference wall 78 (see Figs. 3 and 4), the lifting placement section 60a of the document placement section 60 rises (rotates clockwise around the rotation axis 60a1 from the standby position shown by the solid line to the feeding position shown by the broken line in Fig. 2). Then, when an instruction to read the image of the document D (copy instruction) is given by operating the operation panel, the document D is transported by the pickup roller 62 from the upper document D on the document placement section 60 toward the nip between the feed roller 63 and the reverse roller 64 in sequence. At this time, there is a possibility that a plurality of documents D are transported toward the nip between the feed roller 63 and the reverse roller 64, but only the uppermost document D is separated and sent to the downstream transport path by the separation of the feed roller 63 and the reverse roller 64 in the FRR method. In this embodiment, the pickup roller 62 is configured to be movable up and down by a moving mechanism (not shown), and moves from the standby position shown by the dashed lines in Figures 2 and 3 so as to abut on the surface of the uppermost document D on the document loading section 60 when the feeding operation is started.

[0023] Thereafter, the document D conveyed to the conveying path abuts against the nip of the first conveying roller pair 65 (abutting roller pair) that is in a stopped state of rotation, and is subjected to skew correction (oblique feed correction). The skew-corrected document D is then conveyed downstream by the first conveying roller pair 65 that has started to rotate, and after passing the position of the document detection sensor S10 (registration sensor), is conveyed by the second and third conveying roller pairs 66, 67, and conveyed to the position of the first image reading unit 18 while being guided by the conveying guide plate. Then, at the position of the first image reading unit 18, the image on the front side of the document D is optically read. Thereafter, the document D from which the image has been read is transported to the position of the second image reading unit 80 by the third and fourth transport roller pairs 67, 68. Then, at the position of the second image reading unit 80, the image on the back side of the document D is optically read. When the image information on the back side of the document D is not to be read (when a mode for reading only the image information on the front side is set), the document D passes directly through the position of the second image reading unit 80 without reading the image by the second image reading unit 80 as described above. Thereafter, the document D is conveyed by the fourth and fifth conveyance roller pairs 68 and 69 to the position of the discharge roller pair 70. Then, the document D is conveyed by the discharge roller pair 70 and discharged onto the document discharge section 61. When multiple originals D are loaded on the original placement section 60 and images are to be formed on those originals D, the multiple originals D on the original placement section 60 are transported continuously with intervals between them, and the series of original transport operations described above is repeated.

[0024] Hereinafter, the characteristic configuration and operation of the document transport device 10 serving as a feeding device in this embodiment will be described in detail with reference to Figs. 3 to 5 etc. In this embodiment, the document transport device 10 previously described with reference to FIG. 2 etc. functions as a feeding device that feeds the document D as a sheet in a predetermined feeding direction. The document transport device 10 serving as a feeding device is provided with a document placement section 60 serving as a placement section on which a document D (sheet) can be placed.

[0025] Here, the document placing section 60 (placing section) in this embodiment is provided with a lifting placing section 60a which raises the document D (sheet) placed on the document placing section 60 from a standby position (the position shown by the solid lines in Figures 2 and 3) to a feeding position (the position shown by the dashed lines in Figures 2 and 3) when the feeding operation previously described using Figure 2 is started. The lifting and lowering placement section 60a is configured to be rotatable (liftable) around a rotation axis 60a1 located at the boundary with a fixed portion of the document placement section 60 by being driven by a motor (not shown). When the document D is not set on the document placement section 60, the lifting and lowering placement section 60a is rotated (lifted) to be located at a standby position shown by a solid line in Fig. 3, and when the document D is set on the document placement section 60, the lifting and lowering placement section 60a is rotated (lifted) to be located at a feed position shown by a dashed line in Fig. 3. By providing such a lifting and lowering placement section 60a, the ease of setting the document D on the document placement section 60 is improved. Whether or not the document D is placed on the document placement unit 60 is detected by a first detection sensor S1 (or a second detection sensor S2) which will be described later. The state where the lift placement unit 60a is located at the standby position is detected by the lift home position sensor S3. Furthermore, the state where the uppermost document D on the lift placement unit 60a is located at the feeding position is detected by the document detection sensor S8.

[0026] Now, with reference to FIGS. 3, 4, etc., the document transport device 10 (feeding device) in the present embodiment is provided with a filler 75 (movable member) and a first detection sensor S1 (first detection means). The filler 75 is pushed by the downstream tip of the document D (sheet) placed on the document loading section 60 in the feeding direction, and rotates around the support shaft 75a from a reference position (the position shown by the solid line in Figures 3 and 4) to a pushing position (the position shown by the dashed line in Figures 3 and 4, which is the detection position of the first detection sensor S1). The first detection sensor S1 detects the rotation of the feeler 75 from a reference position (or a pushed position) to a pushed position (or the reference position).

[0027] More specifically, a weight 76 for maintaining the position at the reference position is provided at the bottom of the filler 75. When the filler 75 is located at the reference position, the weight 76 abuts against a stopper portion 72 formed on the housing so that the filler 75 does not rotate beyond that position in the clockwise direction in FIG. The first detection sensor S1 is a transmission type photosensor, and is installed in a recess 78a (see FIG. 4) of the reference wall 78. The recess 78a of the reference wall 78 is formed so as to be recessed from the reference wall 78 to the downstream side in the feeding direction, and is for storing the filler 75 rotated to the pushing position so as not to protrude upstream from the reference wall 78 (so as not to interfere with the feeding of the document D). As explained above, when the document D is set on the document placement section 60 so that the leading edge of the document D (the leading edge on the left side in Figs. 3 and 4) hits the reference wall 78, the feeler 75 is pushed by the leading edge of the document D and rotates counterclockwise in Fig. 3 around the support shaft 75a. When the feeler 75 rotates to the pushing position, the feeler 75 enters between the light emitting element and the light receiving element of the first detection sensor S1, and the sensor output changes (changes from OFF to ON). This allows the document D to be detected as being set on the document placement section 60. When all the documents D on the document placement section 60 are removed and the filler 75 in the pushing position (detection position) rotates toward the reference position, the sensor output of the first detection sensor S1 changes (from an ON state to an OFF state), and it is detected that no documents D are set on the document placement section 60. In the present specification and the like, this state is referred to as "a state in which the first detection sensor S1 detects the rotation of the filler 75 from the pushing position to the reference position."

[0028] Here, in the document placement section 60 (placement section) of the document transport device 10 (feeding device) in this embodiment, a second detection sensor S2 that detects a state in which a document D (sheet) is placed on the document placement section 60 is provided. Specifically, the second detection sensor S2 is disposed near the upstream side in the feeding direction (on the right side in Figs. 3 and 4) of the filler 75 and the first detection sensor S1. This positional relationship (the second detection sensor S2 is located upstream of the filler 75) does not change whether the lift placement unit 60a is raised to the feeding position or lowered to the standby position. In addition, the position of the second detection sensor S2 in the feeding direction is set to a position where it can detect the document D with its leading edge abutting the filler 75, assuming that the filler 75 is fixed to the reference position, and where the document D in that state can be fed by the pickup roller 62 at the feeding position.

[0029] In this embodiment, a reflective photosensor (which receives light by a light receiving element after light emitted from a light emitting element is reflected by a detection object) is used as the second detection sensor S2. Specifically, when the document D is set on the placement surface of the document placement section 60, the light emitted from the light emitting element of the second detection sensor S2 is reflected by the document D, and the reflected light is received by the light receiving element, causing the sensor output to change (from OFF to ON). This allows the setting of the document D on the document placement section 60 to be detected.

[0030] The second detection sensor S2 (reflective photosensor) is disposed so that its detection surface is located on the placement surface (upper surface) of the document placement section 60 or at a lower position. Specifically, as shown in Fig. 4, the second detection sensor S2 is formed so that its detection surface (a sensor surface that enables light emission from a light-emitting element and reception by a light-receiving element of reflected light from a detected object) is exposed without protruding from an opening formed in the lift-and-lower placement section 60a. This prevents the occurrence of a problem such as the document D getting caught on the second detection sensor S2 during a feeding operation or when the document is set. In order to prevent erroneous detection, it is preferable that the second detection sensor S2 (reflective photosensor) is less affected by disturbance light.

[0031] In this embodiment, after the first detection sensor S1 detects the rotation of the filler 75 from the reference position to the pushing position (rotation around the support shaft 75a from the position shown by the solid line in FIG. 3 to the position shown by the dashed line), if the second detection sensor S2 continues to detect the placement of the document D (sheet) on the document placement section 60 during that time, the control is performed to start the feeding operation as if the document D is placed on the document placement section 60 (as if the document D has not been removed). In other words, in this embodiment, even if the document set state detected by the first detection sensor S1 and the second detection sensor S2 is cancelled (even if the document no-set state is detected) when the document set state is still detected by the second detection sensor S2, it is assumed that the document is set, and the subsequent feeding operation is continued without interruption.

[0032] The reason for performing such control is that when a lightweight document D such as thin paper or small size paper is set on the document placement section 60, the user pushes the document D, causing the filler 75 to rotate to the pushing position (detection position), and this state is detected by the first detection sensor S1. However, the moment the user releases the document D, the filler 75, which tries to return to the reference position, may push the document D slightly back to the upstream side in the feeding direction (the right side in Figs. 3 and 4, in the direction away from the reference wall 78). In such a case, the filler 75 moves away from the first detection sensor S1, and the first detection sensor S1 detects that the document is not set. However, even if the document D moves slightly away from the reference wall 78 in the document placement section 60, the pickup roller 62 can still transport the document D downstream in the feeding direction, and interrupting the feeding operation in this state would result in a waste of time. That is, when the document set state is detected only by the first detection sensor S1, it is likely to be erroneously detected as if the document D is not placed on the document placement section 60, even though the document D is actually placed on the document placement section 60. In addition, such erroneous detection by the first detection sensor S1 is also likely to occur when the leading edge of the document D is curled (curved). In contrast, in the present embodiment, in addition to detecting the document set state by the first detection sensor S1, the second detection sensor S2 also detects the document set state. Even if the detection of the document set state by the first detection sensor S1 is canceled, the feeding operation is not interrupted as long as the detection of the document set state by the second detection sensor S2 continues, so that the problem of the document D being mistakenly detected as not being placed on the document placement section 60 when it is actually placed thereon is less likely to occur. If the first detection sensor S1 and the filler 75 are not provided and the second detection sensor S2 alone is used to detect the document set state, it is necessary to use the second detection sensor S2 with high detection accuracy since the detection is performed independently. In such a case, if the punch holes of the document D with punch holes are positioned on the detection surface, there is a high possibility that the document is erroneously detected as not being set. There is also a possibility that the second detection sensor S2 may detect foreign matter such as dust or dirt other than the document D as the document. Therefore, as in the present invention, it is preferable to use both the detection of the document set state by the first detection sensor S1 and the filler 75 and the detection of the document set state by the second detection sensor S2.

[0033] In this embodiment, the second detection sensor S2 can detect a state in which all of the documents D (sheets) placed on the document placement section 60 have been removed. That is, the second detection sensor S2 also functions as an end detection sensor that detects an end state of the documents D on the document placement section 60. Specifically, when all the documents D on the document placement section 60 are gone, the light emitted from the light-emitting element of the second detection sensor S2 is not received by the light-receiving element as reflected light, and the sensor output changes (changes from ON to OFF). This allows the end of the documents D on the document placement section 60 to be grasped. When the end of the documents D is detected in this way, a message to that effect is displayed on a display panel (not shown) of the image forming apparatus main body 1. As explained above, the feeler 75 of the first detection sensor S1 is more likely to rotate to the reference position as the weight of the document D it comes into contact with (the force it receives from the document D) decreases, so that as the stacking state of the document D on the document placement section 60 approaches the end state, a problem of erroneously detecting that the document D is not placed on the document placement section 60 even though the document D is still placed on the document placement section 60 is more likely to occur. Therefore, it is not preferable to use the first detection sensor S1 as the end detection sensor. In this embodiment, the second detection sensor S2 is used as the end detection sensor, so that erroneous detection of the end state is less likely to occur.

[0034] As shown in FIG. 3 and other figures, in this embodiment, the support shaft 75a of the filler 75 is located below the placement surface of the document placement section 60. In particular, in this embodiment, the support shaft 75a of the filler 75 is positioned below the placement surface of the lift-and-lower placement portion 60a that is positioned at the standby position. By setting it in this way, the filler 75 can be extended in the vertical direction to the feeding position. Specifically, the filler 75 is formed to extend in the vertical direction from a position below the placement surface of the lift placement unit 60a located at the standby position to the feeding position near the pickup roller 62. Therefore, regardless of the elevation and lowering of the elevation placement section 60a, the contact state between the document D on the document placement section 60 and the filler 75 can be maintained. This allows the first detection sensor S1 to properly detect the setting of the document.

[0035] Hereinafter, an example of control in the document transport device 10 using the first and second detection sensors S1 and S2 will be described with reference to FIG. First, when the first detection sensor S1 is turned on (step St1), it is assumed that a document D is placed on the document placement unit 60, and the lifting and lowering placement unit 60a (document tray) that is in the standby position is raised (rotated) to the feeding position (step St2). Thereafter, it is determined whether the first detection sensor S1 is turned off (step St3). As a result, if the first detection sensor S1 is not turned off, it is determined that the original D has not been pushed back by the filler 75, and the feeding operation is started (step St5), and this flow ends. That is, as described above with reference to FIG. 2, the original D is conveyed to the nip between the feed roller 63 and the reverse roller 64 by the pickup roller 62, and then the original D is conveyed toward the image reading units 18, 80. On the other hand, if the first detection sensor S1 is off in step St3, it is determined that the original D has been pushed back by the filler 75, and it is then determined whether the second detection sensor S2 is still on (step St4). As a result, if the second detection sensor S2 is on, it is determined that the original D is placed on the original placement section 60, and the control flow from step St5 onwards is carried out. On the other hand, if the second detection sensor S2 is not on in step St4, it is assumed that no document D is placed on the document placement section 60 (it is assumed to be in the end state), and the lifting / lowering placement section 60a (document tray), which was in the feeding position until the lifting / lowering home position sensor S3 turned on, is lowered (rotated) to the standby position (steps St6, St7), and this flow is terminated.

[0036] <Variation 1> Referring to FIG. 6, the document transport device 10 (image forming device 1) as variant example 1 is triggered by the detection of the document set state by the second detection sensor S2 to return from the power saving mode and raise the lifting and lowering placement section 60a to the feeding position. Specifically, the "power saving mode" is a control mode in which, for the purpose of energy saving, the power consumption of the image forming apparatus 1 is controlled to be reduced compared to when printing (normal power mode). Specifically, when a timer built into the apparatus determines that the user has not used the image forming apparatus 1 for a predetermined period of time, the power supplied to the heater of the fixing device 20, the display panel (not shown), etc. is cut off (or reduced). In the first modification, when the power saving mode is being executed and the second detection sensor S2 detects that the document D (sheet) is placed on the document placement section 60, the power saving mode is cancelled and the normal power mode for printing is restored. By controlling in this way, it becomes possible to quickly return from the power saving mode in accordance with the user's operation of setting the document D. In addition, in the first modification, when the second detection sensor S2 detects that the document D is placed on the document placement section 60, the lift placement section 60a is controlled to be raised from the standby position to the feeding position. By controlling in this manner, it becomes possible to start the feeding operation promptly in accordance with the setting operation of the document D by the user. Hereinafter, an example of control in the document transport device 10 triggered by the detection by the second detection sensor S2 described above will be described with reference to FIG. First, it is determined whether the first detection sensor S1 is on (step St1), and also whether the second detection sensor S2 is on (step St10). As a result, if it is determined that the second detection sensor S2 has been turned on, the power saving mode is returned to the normal power mode (step St11), and the lifting and lowering placement section 60a (original tray), which was in the standby position, is raised (rotated) to the feeding position (step St2). Thereafter, the control flow from step St3 onwards is carried out in the same manner as that described above with reference to FIG.

[0037] <Variation 2> As shown in FIGS. 7 and 8, the document transport device 10 (feeding device) in the second modification does not use a reflective photosensor as the second detection sensor, but uses a transmissive photosensor as the second detection sensor S12. In detail, the document placing section 60 (lifting and lowering placing section 60a) is provided with a second filler 79 which is pushed by the document D (sheet) placed on the document placing section 60 and rotates about a second support shaft 79a from a protruding position where it protrudes from the placing surface of the document placing section 60 to a non-protruding position where it does not protrude. The second detection sensor S22, which is a transmissive photosensor, is installed at a position in the document loading section 60 (lifting loading section 60a) that does not protrude from the loading surface, and detects the rotation of the second filler 79 from the protruding position (or non-protruding position) to the non-protruding position (or protruding position). Specifically, when the document D is set on the document placement section 60, the second feeler 79 is pushed by the document D and rotates counterclockwise in FIG. 7 around the support shaft 79a. When the second feeler 79 rotates from the protruding position to the non-protruding position, the second feeler 79 enters between the light emitting element and the light receiving element of the second detection sensor S22, and the sensor output changes (from the OFF state to the ON state). This allows the document D to be detected as being set on the document placement section 60. Furthermore, when all the documents D on the document placing section 60 are removed and the second filler 79, which is in the non-protruding position (detection position), rotates toward the protruding position, the sensor output of the second detection sensor S22 changes (from an on state to an off state), and it is detected that no documents D are set on the document placing section 60 (the end state is detected). In the second variant, in addition to detecting the document set state by the first detection sensor S1, the second detection sensor S22 also detects the document set state. Even if the detection of the document set state by the first detection sensor S1 is canceled, the feeding operation continues as long as the detection of the document set state by the second detection sensor S22 continues, so that the problem of erroneously detecting that the document D is not placed on the document placement section 60 when the document D is actually placed on the document placement section 60 is less likely to occur. Furthermore, by using a transmission type photosensor using the second filler 79 as the second detection sensor S22, the problem of detecting foreign matter such as dust or dirt other than the original D as the original is less likely to occur.

[0038] As described above, the document transport device 10 in this embodiment is a feeding device that feeds the document D (sheet) in a predetermined feeding direction, and is provided with a document placement section 60 (placement section) on which the document D can be placed. Also provided are a feeler 75 that is pushed by the leading end of the document D placed on the document placement section 60 on the downstream side in the feeding direction to rotate from a reference position to a pushing position around a support shaft 75a, and a first detection sensor S1 that detects the rotation of the feeler 75 from the reference position (or pushing position) to the pushing position (or reference position). The document placement section 60 is provided with a second detection sensor S2 that detects a state in which the document D is placed on the document placement section 60. This makes it possible to prevent a problem in which, even though the document D is actually placed on the document placement section 60, it is erroneously detected that the document D is not placed thereon.

[0039] In this embodiment, the present invention is applied to a document transport device 10 installed in a monochrome image forming apparatus 1, but the present invention can naturally also be applied to a document transport device installed in a color image forming apparatus. Furthermore, in this embodiment, the present invention is applied to a document transport device 10 installed in an electrophotographic image forming apparatus 1, but the application of the present invention is not limited to this, and the present invention can also be applied to document transport devices installed in other types of image forming apparatus (for example, an inkjet image forming apparatus, a stencil printer, etc.). In addition, in this embodiment, the present invention is applied to a document transport device 10 in which a lifting and lowering loading section 60a is provided on the document loading section 60, but the present invention can naturally be applied to a document transport device in which a lifting and lowering loading section is not provided on the document loading section. In addition, in this embodiment, the present invention is applied to a document transport device 10 provided with a second image reading unit 80, but the present invention can naturally also be applied to a document transport device that does not have a second image reading unit. In addition, in this embodiment, the present invention is applied to the document transport device 10 as a feeding device, but the application of the present invention is not limited to this, and for example, the present invention can also be applied to the paper feeding sections 12-14 as feeding devices that feed paper P as a sheet. Even in these cases, the same effects as those of this embodiment can be obtained.

[0040] It is clear that the present invention is not limited to the present embodiment, and that the present embodiment may be modified as appropriate within the scope of the technical concept of the present invention in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and may be any number, position, shape, etc. suitable for implementing the present invention.

[0041] In this specification, a "sheet" is defined as an original D set in the original transport device 10, and includes not only ordinary paper, but also all sheet-like materials such as coated paper, label paper, OHP sheets, film, sheets with punched holes, etc., and further includes paper P fed by paper feeding sections 12-15 as a feeding device. [Explanation of symbols]

[0042] 1 Image forming apparatus (image forming apparatus main body), 10 Document transport device (feeding device), 60 Original placement section (placement section), 60a lifting and lowering unit, 60a1 spindle, 61 Original output section, 62 Pickup roller, 63 Feeding roller, 64 Reverse roller, 75 1st Filler (Filler), 75a spindle, 79 Second Filler, 79a 2nd spindle, S1 First detection sensor, S2 Second detection sensor (reflective photosensor), S3 Lift home position sensor, S22 Second detection sensor (transmissive photosensor), D Manuscript (sheet). [Prior art documents] [Patent documents]

[0043] [Patent Document 1] JP 2007-331940 A

Claims

1. A feeding device that feeds a sheet in a predetermined feeding direction, A placement section on which a sheet can be placed; a filler that is pushed by a leading end of the sheet placed on the sheet placement unit on a downstream side in a sheet feeding direction and rotates about a support shaft from a reference position to a pushing position; a first detection sensor that detects rotation of the filler from the reference position or the pushing position to the pushing position or the reference position; Equipped with the placement section includes a second detection sensor that detects a state in which a sheet is placed on the placement section, A feeding device characterized in that, even if the first detection sensor detects the rotation of the filler from the reference position to the pushing position and then detects the rotation of the filler from the pushing position to the reference position, if the second detection sensor continues to detect the placement of a sheet on the placement section during that time, the feeding device starts a feeding operation as if a sheet is placed on the placement section.

2. The feeding device as described in Claim 1, characterized in that the second detection sensor is arranged upstream of the filler in the feeding direction.

3. A feeding device as described in claim 1 or claim 2, characterized in that the second detection sensor is a reflective photosensor arranged so that its detection surface is located on the loading surface of the loading section or at a lower position therebetween.

4. A second filler is provided which is pushed by a sheet placed on the loading section and rotates about a second support shaft from a protruding position protruding from the loading surface of the loading section to a non-protruding position not protruding, 3. The feeding device according to claim 1, wherein the second detection sensor is a transmission type photosensor that detects rotation of the second filler from the protruding position or the non-protruding position to the non-protruding position or the protruding position.

5. The feeding device is installed in an image forming apparatus, A feeding device as described in any one of claims 1 to 4, characterized in that when a power saving mode is being executed in which the power consumption in the image forming device is controlled to be reduced compared to when printing, when the second detection sensor detects that a sheet has been placed on the loading section, the power saving mode is cancelled and the device is returned to the normal power mode when printing.

6. The loading section includes a lifting loading section that lifts the sheet loaded on the loading section from a standby position to a feeding position when a feeding operation is started, A feeding device as described in any one of claims 1 to 5, characterized in that when the second detection sensor detects that a sheet is placed on the loading section, the lifting and lowering loading section is raised from the standby position to the feeding position.

7. A feeding device as described in any one of claims 1 to 6, characterized in that the second detection sensor is capable of detecting a state in which all of the multiple sheets placed on the loading section have been removed.

8. A feeding device as described in any one of claims 1 to 7, characterized in that the support shaft of the filler is located below the loading surface of the loading section.

9. A feeding device as described in any one of claims 1 to 7, characterized in that it is a document transport device in which a document as a sheet is placed on the placement section.

10. An image forming apparatus comprising a feeding device according to any one of claims 1 to 9.

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