Document feeding device and image forming apparatus equipped therewith

Abstract

To provide a document feeding device that can suppress document jams in the document transport path, and an image forming apparatus equipped with the same. [Solution] A document feeder comprising a document placement section, a document transport path, and a document supply section, wherein the document supply section comprises a support member, a roller holder rotatably attached to the support member, a take-up roller rotatably attached to the roller holder to send documents to the document transport path, a drive mechanism that rotates the roller holder and raises and lowers the take-up roller, a document stopper rotatably attached to the support member, and a lock / release mechanism, wherein the document stopper is rotatable between a restricting position that restricts the supply of documents to the document transport path and a release position that releases the restriction on the supply of documents to the document transport path, and the lock / release mechanism is switchable between a locked state in which the document stopper is locked in the restricting position and a released state that releases the lock and allows the document stopper to rotate to the release position, in conjunction with the rotational movement of the roller holder.

Description

Technical Field

[0004] , , , , , , , , ,

[0001] The present invention relates to a document feeder and an image forming apparatus including the same.

Background Art

[0002] As a document feeder provided in an image forming apparatus, for example, the document conveyance apparatus of Patent Document 1 includes a document tray, a paper discharge tray, a document conveyance path provided between the document tray and the paper discharge tray, a pickup roller that feeds the documents placed on the document tray one by one to the document conveyance path, a roller holder that holds the pickup roller rotatably and vertically movably, and a document stopper provided rotatably on the roller holder. According to this document conveyance apparatus, when the pickup roller is in the raised position, the rotating end of the document stopper descends to regulate one end (the downstream end in the document conveyance direction) of the document before conveyance to the regulation position, and when the pickup roller descends and shifts to the document conveyance state, the rotating end of the document stopper ascends to the regulation release position to release the regulation of the movement of one end of the document in the conveyance direction.

[0003] In a general document feeder including the document conveyance apparatus of Patent Document 1, usually, a pair of document guides that align both ends in the width direction (the direction orthogonal to the document conveyance direction) of the documents placed on the document tray are provided movably in the width direction, and marks (lines, inverted triangles, etc.) indicating the allowable loading capacity of the documents on the document tray are provided on the inner surface of one (the inner side in the width direction) of the document guides. In such a general document feeder, the documents having an amount (number of sheets) not exceeding the height of the mark indicating the allowable loading capacity must be placed on the document tray.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, even if a user accidentally places more documents (number of pages) than the allowable limit into the document tray, the document stopper will retract to the release position as the pickup roller rotates and descends. This can cause the pickup roller to forcibly pull in the document at the top, potentially resulting in a document jam within the document transport path.

[0006] The present invention aims to provide a document feeding device and an image forming apparatus equipped therewith, which have been designed with these circumstances in mind. [Means for solving the problem]

[0007] The present invention provides a document feeding device comprising a document placement section on which documents can be placed, a document transport path on which documents are transported, and a document supply section that supplies documents placed on the document placement section to the document transport path. The document supply section comprises a support member, a roller holder rotatably attached to the support member via a first axis, a take-up roller rotatably attached to the roller holder via a second axis to feed documents placed on the document placement section one by one to the document transport path, a document stopper rotatably attached to the support member via a third axis, and a lock / release mechanism. The document stopper is rotatable between a restricting position that restricts the supply of documents to the document transport path and a release position that releases the restriction on documents to the document transport path. The lock / release mechanism is configured to be switchable between a locked state in which the document stopper is locked in the restricting position and a released state that releases the lock and allows the document stopper to rotate to the release position, in conjunction with the rotational movement of the roller holder.

[0008] The present invention provides an image forming apparatus comprising a document reading device, a document feeding device for feeding a document to the document reading device, and an image forming apparatus main body for forming an image on a sheet-like recording medium based on image data of a document read by the document reading device. [Effects of the Invention]

[0009] According to the document feeder of the present invention, the lock / unlock mechanism is configured to be linked to the rotational movement of the roller holder. Therefore, depending on the degree of descent of the feed roller accompanying the descent of the roller holder due to rotation, the mechanism switches between a locked state in which the document stopper is locked in a restricting position and an unlocked state in which the lock is released and the document stopper is allowed to rotate to the release position. Consequently, if a document exceeding the loading capacity is placed on the document placement section and the feed roller descends and contacts the document at the uppermost position, the amount of descent of the roller holder decreases, and the lock / unlock mechanism does not release the locked state of the document stopper at the restricting position. Therefore, it is possible to avoid a situation in which a document exceeding the loading capacity is forcibly sent into the document transport path, causing a document jam. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view of an image forming apparatus equipped with a document feeding device according to the first embodiment, viewed from the front. [Figure 2] Figure 1 is a perspective view showing the document feeder and image reading device. [Figure 3] Figure 1 is a perspective view showing the document feeder with the opening / closing member in the open position. [Figure 4] Figure 1 is a cross-sectional view showing the main parts of the document feeder and image reading device. [Figure 5] This is a perspective view showing the lower side of the opening / closing member in the open position in the document feeder of the first embodiment. [Figure 6] This is a magnified perspective view of the roller holder on the lower side of the opening / closing member in the document feeder of the first embodiment, when it is in the open position. [Figure 7] This is a perspective view showing the state in which the roller holder of the opening / closing member in the document feeder of the first embodiment is raised relative to the document. [Figure 8] This is a cross-sectional view from the front showing the state in which the roller holder of the opening / closing member of the document feeder of the first embodiment is raised. [Figure 9] Figure 1 is a perspective view showing the document stopper included in the document feeder. [Figure 10]It is a front view showing a document stopper included in the document feeder shown in FIG. 1. [Figure 11] It is a cross-sectional view showing the document stopper along the line B - B shown in FIG. 10. [Figure 12] It is a perspective view showing the state where the roller holder in the document feeder of the first embodiment has descended. [Figure 13] It is a cross-sectional view taken from the front side showing the state where the roller holder in the document feeder of the first embodiment has descended. [Figure 14] It is a cross-sectional view taken from the front side showing the state where the lock of the document stopper is released and the document is being conveyed following FIG. 13. [Figure 15] It is a cross-sectional view taken from the front side showing the placed document detection unit in the document feeder of the first embodiment. [Figure 16] It is a cross-sectional view taken from the front side showing the state where the placed document detection unit has detected the placed document following FIG. 15. [Figure 17] It is a schematic block diagram showing the system configuration of the control unit in the document feeder of the first embodiment. [Figure 18] It is a cross-sectional view taken from the front side showing the state where the roller holder of the opening / closing member in the document feeder of the second embodiment has ascended. [Figure 19] It is a schematic cross-sectional view taken from the front side showing the placed document detection unit in the document feeder of the third embodiment. [Figure 20] It is a schematic cross-sectional view taken from the front side showing the state where the placed document detection unit has detected the placed document following FIG. 19.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. Note that the following description is illustrative in all respects and should not be construed as limiting the present invention.

[0012] (First Embodiment) [Overall configuration of the image forming apparatus] Figure 1 is a schematic cross-sectional view of an image forming apparatus 1 equipped with a document feeder 3 according to the first embodiment, viewed from the front. In each figure, including Figure 1, the symbol X represents the width direction (front-to-back direction), the symbol Y represents the left-to-right direction, the symbol Z represents the up-to-down direction (vertical direction), and the symbol H represents the document supply direction (transport direction), which is the direction in which the document G is supplied by the document feeder 3, which will be described later.

[0013] The image forming apparatus 1 according to this embodiment is a color image forming apparatus that forms multi-color and monochrome images on a sheet of paper P. The image forming apparatus 1 performs image forming processing according to image data read by the image reading device 2 or image data transmitted from an external source. The image forming apparatus 1 may also be a monochrome image forming apparatus.

[0014] The image forming apparatus 1 comprises an image forming apparatus body 10 for forming an image on a sheet of paper P. The image forming apparatus body 10 includes an image forming unit 11 and a paper transport unit 12.

[0015] The image forming unit 11 includes an exposure device 4, a developing device 5, a photoreceptor drum 6 that acts as an electrostatic latent image carrier, a cleaning device 7, a charging device 8, a primary transfer device 9, a secondary transfer device 13, and a fixing device 14. The paper transport unit 12 includes a paper feed tray 15 that holds one or more sheets of paper P on which an image is formed, a manual feed tray 16 that also holds one or more sheets of paper P on which an image is formed, an output roller 17, and an output tray 18.

[0016] The paper transport unit 12 further includes a paper transport path W1 for transporting sheets of paper P, contained in the paper feed tray 15 or manual feed tray 16, one sheet at a time, to the secondary transfer unit 13 and the fuser unit 14, and then to the discharge tray 18. The paper transport path W1 is equipped with pickup rollers 19a, 19b, transport roller 20a, registration roller 21, transfer roller 13a in the secondary transfer unit 13, heat roller 14a and pressure roller 14b in the fuser unit 14, and discharge roller 17 for transporting the paper P.

[0017] Next, the image formation process performed in the image forming unit 11 will be briefly explained. In the image forming unit 11, the surface of the photoreceptor drum 6, which has been uniformly charged by the charging device 8, is laser-exposed by the exposure device 4 according to the image data (image information), and electrostatic latent images are formed on the photoreceptor drum 6. The electrostatic latent images formed on the photoreceptor drum 6 are developed by the developing device 5 and manifested as toner images. The toner images on the photoreceptor drum 6 are intermediately transferred onto the intermediate transfer belt 9c, which is stretched over the drive roller 9a and driven roller 9b in the primary transfer device 9 and rotated in a predetermined rotation direction E. The toner images on the intermediate transfer belt 9c, which rotates in a predetermined rotation direction E, are transported to the secondary transfer device 13, which has a secondary transfer roller 13a. The toner images intermediately transferred onto the intermediate transfer belt 9c are transported from the paper feed tray 15 or the manual feed tray 16 to the transfer nip, which is the contact point between the intermediate transfer belt 9c and the secondary transfer roller 13a, and are transferred at the transfer nip. Here, the paper P transported to the transfer nip section is paper P that has been collected in the paper feed tray 15 or manual feed tray 16, drawn one sheet at a time into the paper transport path W1 by the pickup roller 19a or 19b, transported via the transport roller 20a, and temporarily stopped by the register roller 21. The register roller 21 then resumes transporting the temporarily stopped paper P toward the transfer nip section at the timing to align it with the toner image on the intermediate transfer belt 9c. The paper P onto which the toner image has been transferred in the transfer nip section is sent to the fixing nip section, which is the contact point between the heat roller 14a and the pressure roller 14b of the fixing device 14, the surfaces of which are controlled to a predetermined temperature. The toner image transferred to the paper P is melted by heat and pressure in the fixing nip section and fixed to the paper P. The paper P with the fixed toner image continues to be transported along the paper transport path W1 and is discharged onto the discharge tray 18 via the discharge roller 17. Here, if image formation is to be performed on the back side of the paper P as well as the front side, the paper P is transported in the reverse direction from the discharge roller 17 to the inverted paper transport path W2. The paper P is then inverted via the inverted transport roller 20b and guided again to the registration roller 21. Then, after the toner image is formed and fixed on the back side of the paper P in the same way as on the front side, the paper P is discharged toward the discharge tray 18.

[0018] [Image reading device] The image reading device 2 included in the image forming apparatus 1 will now be described. An image reading device 2 for reading the image of the original document G is provided on the upper part of the main body 10 of the image forming apparatus. The image reading device 2 includes an original document tray 22 (specifically, an original document tray glass) on which the original document G is placed, and an original document reading plate section 23 (specifically, an original document reading glass). An original document feeder 3 is also provided above the original document tray 22 and the original document reading plate section 23. In the image forming apparatus 1, the image of the original document G read by the image reading device 2 is sent to the main body 10 of the image forming apparatus as image data, and the image is recorded on the paper P.

[0019] The image reading device 2 includes an image reading unit 25 (specifically, an image reading unit) having an image sensor 24 for reading an image of the document G. The image reading device 2 scans the document G placed on the document placement table 22 while moving the image reading unit 25 along the lower surface of the document placement table 22 to one side of the document G in the left-right direction Y, thereby reading the image of the document G placed on the document placement table 22 with the image sensor 24. The reciprocal movement of the image reading unit 25 in the left-right direction Y relative to the housing 26 is performed by a drive unit (drive motor) not shown. The image reading device 2 can also stop the image reading unit 25 at a position below the document reading plate section 23 and scan the document G as it is transported by the document feeder 3 (described later) and passes over the document reading plate section 23, and read it with the image sensor 24.

[0020] [Document feeder] Figure 2 is a perspective view showing the document feeder 3 and image reading device 2 shown in Figure 1. Figure 3 is a perspective view showing the document feeder 3 shown in Figure 1 with the opening / closing member 33 in the open position. Figure 4 is a cross-sectional view showing the main parts of the document feeder 3 and image reading device 2 shown in Figure 1. As shown in Figures 1 to 4, the document feeder 3 includes a document placement section 31 on which multiple documents G can be placed, a document transport path W3 that guides the documents G placed on the document placement section 31 to the document reading plate section 23 of the image reading device 2, a document supply section 32 that transports (supplies) the documents placed on the document placement section 31 one by one to the document transport path W3, an opening / closing member 33 (opening / closing cover member), and a document discharge section 34. The document G placed on the document placement section 31 is supplied to the document transport path W3 by the document supply section 32, transported to the document reading plate section 23 of the image reading device 2 by the document transport system 36 including the document transport roller 35, read by the image sensor 24 of the image reading section 25, and then discharged to the document discharge section 34. In this embodiment, the document feeding device 3 is of the type in which the document supply section 32 is provided on the inner surface side of the opening / closing member 33.

[0021] In this embodiment, the document placement section 31 is provided with a pair of guide members 37 (see Figure 2) that restrict the position of the document G being transported on the document transport path W3 in a direction perpendicular to the transport direction H (width direction X). The guide members 37 may be provided so as to be movable (slidable) in the width direction X relative to the document placement section 31 so as to guide the document G according to its size. In that case, the guide members 37 may be configured to reciprocate in the width direction X with respect to the center of the document G in the width direction X. Furthermore, a mark F (for example, an inverted triangle, a straight line, or a mark combining these) indicating the thickness of a stack of documents that is permitted to be placed on the document placement section 31 may be provided on the inner surface of the guide member 37 on the far side in the width direction X (see Figures 3 and 4).

[0022] The document feeder 3 of this embodiment comprises a lower unit 38 including a document placement section 31, a document transport system 36, and a document discharge section 34, and an upper unit 39 rotatably attached to the lower unit 38 via a pivot shaft 40 (see Figure 4) so ​​as to be able to open and close the upstream portion of the document transport direction H in the document transport path W3.

[0023] The opening / closing member 33 constitutes part of the upper unit 39, and both ends of the opening / closing member 33 on the left side in the width direction X are rotatably attached to both ends of the opening / closing member 33 on the left side in the width direction X via a pivot shaft 40 having an axis in the width direction X. This makes it possible to switch the opening / closing member 33 from the closed state (see Figure 2) to the open state (see Figure 3) by rotating the right end upward around the pivot shaft 40. Inside the opening / closing member 33, a plurality of guide ribs 41 (see Figure 3) that constitute the document transport path W3 are formed extending in the left-right direction. Furthermore, a part of the document supply section 32 that constitutes the upper unit 39 is provided in the middle of the width direction X inside the opening / closing member 33.

[0024] Figure 5 is a perspective view showing the lower side of the open / closed member 33 in the open state in the document feeder 3 of the first embodiment. Figure 6 is a perspective view showing an enlarged view of the roller holder 44 on the lower side of the open / closed member 33 in the open state in the document feeder 3 of the first embodiment. Figure 7 is a perspective view showing the state in which the roller holder 44 of the open / closed member 33 in the document feeder 3 of the first embodiment is raised relative to the document G. As shown in Figures 3 to 7, the document supply unit 32 includes a support member 42, a roller holder 44 rotatably attached to the support member 42 via a first shaft 43, a take-up roller 46 rotatably attached to the roller holder 44 via a second shaft 45 to feed the document G placed on the document placement unit 31 one by one to the document transport path W3, a supply roller 47 rotatably attached to the roller holder 44 via the first shaft 43, and a drive mechanism (not indicated) that raises and lowers the take-up roller 46 by rotating the roller holder 44. Here, "rotation" means that the object in question rotates 360 degrees or more, while "rotation" means that the object in question rotates less than 360 degrees.

[0025] The support member 42 consists of at least one pair of guide ribs 41 and rotatably supports both ends of the rectangular frame-shaped roller holder 44 in the width direction X on the downstream side of the document transport direction H via the first shaft 43 (see Figures 3 and 4). The feed roller 46 is positioned upstream of the supply roller 47 in the document transport direction H. The supply roller 47 transports the document G sent from the feed roller 46 to the document transport path W3. When the opening / closing member 33 is closed, a separation pad 48 (see Figure 4) is provided in the lower unit 38 at a position opposite the supply roller 47, and when two documents G are sent between the supply roller 47 and the separation pad 48, the separation pad 48 restricts the transport of the lower document G.

[0026] The drive mechanism includes a drive motor 50 (see Figure 3) provided on the lower unit 38 and a power transmission mechanism 51 that transmits rotational force from the output shaft of the drive motor 50 to the pull-in roller 46. As will be described in detail below, the mechanism is configured to rotate the pull-in roller 46 with rotational force Ra in the forward direction from the output shaft of the drive motor 50, while simultaneously rotating the roller holder 44 downward to lower the pull-in roller 46, and to rotate the roller holder 44 upward with rotational force Rb in the reverse direction from the output shaft of the drive motor 50 to raise the pull-in roller 46. In Figures 3 to 7, the reference numeral (51) is also used to indicate each of the multiple components that constitute the power transmission mechanism 51, which will be described later.

[0027] As shown in Figure 3, the power transmission mechanism 51 is connected to the output shaft of the drive motor 50 and includes a drive gear 51a provided on the lower unit 38 and a driven gear 51b provided on the upper unit 39 so as to be able to mesh with the drive gear 51a and to be rotatable. The drive gear 51a is located on the left side of the lower unit 38, towards the rear in the width direction X, and the driven gear 51b is located on the rear in the width direction X in the middle of the left-right direction Y of the upper unit 39. By closing the upper unit 39 from its open state, the driven gear 51b meshes with the drive gear 51a.

[0028] Furthermore, as shown in Figures 5 and 6, in addition to the first shaft 43 that transmits rotational force from the driven gear 51b to the pull-in roller 46, the power transmission mechanism 51 in this embodiment includes a torque limiter 52, a drive timing pulley 53, a driven timing pulley 54, a timing belt 55 wrapped around the drive timing pulley 53 and the driven timing pulley 54, a first one-way clutch 56, and a second one-way clutch 57.

[0029] The driven gear 51b is connected to the rear end of the first shaft 43, which is the drive shaft, in the width direction X. The torque limiter 52 comprises a shaft portion, a sleeve through which the shaft portion is inserted, a housing through which the shaft portion and sleeve are inserted, and a torque spring and drive key provided between the shaft portion and the housing. A cylindrical limiter coupling 59 is provided between the torque limiter 52 and the roller holder 44, and the limiter coupling 59 connects the housing of the torque limiter 52 to the roller holder 44. The front end of the first shaft 43 in the width direction X is connected to the rear end of the shaft portion of the torque limiter 52 in the width direction X. The front end of the first shaft 43 in the width direction X is connected to the rear end of the drive timing pulley 53 in the width direction X via the shaft portion of the torque limiter 52. The first shaft 43 and the torque limiter 52 are held on the guide rib 41 so as to be rotatable about the rotation axis α3 of the first shaft 43. Further details on the operation of the torque limiter 52 will be provided later.

[0030] The drive timing pulley 53 is rotatably mounted on the axis of the first shaft 43 in the inner space of the roller holder 44, and the rotational force from the shaft of the torque limiter 52 is transmitted to it. The driven timing pulley 54 is rotatably mounted in the inner space of the roller holder 44 via a second shaft 45 parallel to the first shaft 43, and the rotational force from the drive timing pulley 53 is transmitted to it via the timing belt 55.

[0031] The first one-way clutch 56 is provided between the supply roller 47 and the drive timing pulley 53. The first one-way clutch 56 connects the supply roller 47 and the shaft portion of the drive timing pulley 53 in response to the rotation of the first shaft 43 in the forward rotation direction Ra, causing the supply roller 47 to rotate in the forward rotation direction Ra as the first shaft 43 rotates in the forward rotation direction Ra. On the other hand, the first one-way clutch 56 allows the supply roller 47 to rotate in the forward rotation direction Ra when the rotation of the drive timing pulley 53 is stopped.

[0032] The second one-way clutch 57 is provided between the second shaft 45 of the intake roller 46 and the driven timing pulley 54. The second one-way clutch 57 connects the second shaft 45 of the intake roller 46 and the driven timing pulley 54 to the rotation of the driven timing pulley 54 in the forward rotation direction Ra, causing the intake roller 46 to rotate in the forward rotation direction Ra. On the other hand, the second one-way clutch 57 allows the intake roller 46 to rotate in the forward rotation direction Ra when the rotation of the driven timing pulley 54 is stopped.

[0033] In this way, by using the first one-way clutch 56 and the second one-way clutch 57, even if the rotational drive of the drive motor 50 and the power transmission mechanism 51 is stopped after the leading edge of the document G (the downstream end in the document transport direction H) reaches the roller nip position of the document transport roller 35, the transport force of the document G being transported by the document transport roller 35 can cause both the supply roller 47 and the incoming roller 46 to rotate in the forward rotation direction Ra.

[0034] When the load on the roller holder 44 during rotation of the first shaft 43 is below a predetermined value, the torque limiter 52's shaft, sleeve, and housing rotate together, and the torque limiter 52's housing and limiter coupling 59 rotate together, as described later, causing the roller holder 44 to rotate in conjunction with the rotation of the first shaft 43. At this time, if the first shaft 43 rotates in the forward rotation direction Ra, the roller holder 44 descends due to the rotation in the forward rotation direction Ra, and the supply roller 47 and the retrieval roller 46 rotate in the forward rotation direction Ra. On the other hand, if the first shaft 43 rotates in the reverse rotation direction Rb, the roller holder 44 rises due to the rotation in the reverse rotation direction Rb, but the first one-way clutch 56 and the second one-way clutch 57 block the rotational force in the reverse rotation direction Rb, causing the supply roller 47 and the retrieval roller 46 to stop.

[0035] On the other hand, for example, when the first axis 43 is rotating in the forward rotation direction Ra, if the feed roller 46 comes into contact with the uppermost document Gu of the stack of documents G on the document placement section 31 and the load on the roller holder 44 exceeds a predetermined value, the housing of the torque limiter 52 stops, but the shaft and sleeve rotate together. Therefore, the roller holder 44 stops for each component that rotates in the forward rotation direction Ra from the first axis 43 to the feed roller 46. Also, for example, when the first axis 43 is rotating in the reverse rotation direction Rb, if the feed roller 46 comes into contact with the inner surface of the opening / closing member 33 and the load on the roller holder 44 exceeds a predetermined value, the housing of the torque limiter 52 stops, but the shaft and sleeve rotate together. At this time, each component from the first shaft 43 to the driven timing pulley 54 is rotating in the reverse direction Rb, but the rotational force in the reverse direction Rb is blocked by the first one-way clutch 56 and the second one-way clutch 57, so the supply roller 47 and the pull-in roller 46 stop.

[0036] Therefore, with the power transmission mechanism 51 equipped with a torque limiter 52, when the opening / closing member 33 is in the closed position, the feed roller 46 descends together with the roller holder 44 when the first shaft 43 rotates in the forward rotation direction Ra, and when the feed roller 46 contacts the document G on the document placement section 31, the downward rotation of the roller holder 44 is restricted, and the first shaft 43 can continue to rotate relative to the roller holder 44 which has stopped in the lowered position. As a result, the feed roller 46 presses down on the document G on the document placement section 31 from above, and the uppermost document G can be sent in the document transport direction H by the forward rotation direction Ra of the feed roller 46. On the other hand, when the first shaft 43 rotates in the reverse rotation direction Rb, the feed roller 46 rises together with the roller holder 44, and when the feed roller 46 contacts the opening / closing member 33, the upward rotation of the roller holder 44 is restricted, and the first shaft 43 can continue to rotate relative to the roller holder 44 which has stopped in the raised position. Alternatively, the rotation of the first shaft 43 may be stopped (the drive motor 50 may be turned off) when the roller holder 44 stops in the raised position.

[0037] Figure 8 is a front cross-sectional view showing the state in which the roller holder 44 of the opening / closing member 33 of the document feeder 3 of the first embodiment is raised. Figure 9 is a perspective view showing the document stopper 60 provided in the document feeder 3 shown in Figure 1. Figure 10 is a front view showing the document stopper 60 provided in the document feeder 3 shown in Figure 1. Figure 11 is a cross-sectional view showing the document stopper 60 along the BB line shown in Figure 10. As shown in Figure 8, the document supply unit 32 includes a document stopper 60 that restricts the movement of the document G in the document transport direction H so that the leading edge Ga (see Figure 8) of the document G placed on the document placement unit 31 is aligned with the restricted position (initial position), and a lock / release mechanism 70 that switches the document stopper 60 between a locked state and an unlocked state. Figures 9 to 11 illustrate the posture of the document stopper 60 when it is locked in the restricted position, and the structure of the document stopper 60 will be described below based on this posture.

[0038] As shown in Figures 7 and 8, a pair of document stoppers 60 are provided on the back and front sides of the roller holder 44 in the width direction X (direction of rotation axis X). Since the pair of document stoppers 60 have the same structure, only the structure of one of the document stoppers 60 will be described below. As shown in Figures 9 to 11, the document stopper 60 has a large-diameter shaft portion 61 provided on a rotation axis α1 extending in the width direction X (direction of rotation axis X), a first arm portion 62 protruding to the left in the left-right direction Y from the large-diameter shaft portion 61, and a stopper piece portion 63 hanging downward from the left end of the first arm portion 62.

[0039] Furthermore, in this embodiment, a pair of small-diameter shaft portions 64 are provided on the rotation axis α1 at both ends of the large-diameter shaft portion 61 in the width direction X, and a pair of second arm portions 65 are provided projecting diagonally upward and to the left in the left-right direction Y from the ends of the pair of small-diameter shaft portions 64, and a pair of small, piece-shaped stopper-side locking portions 71 are provided at the tips of the pair of second arm portions 65. The stopper-side locking portions 71 are part of the lock / release mechanism 70 and are integrated with the document stopper 60.

[0040] When the document stopper 60 is viewed from the left-right direction Y, the pair of stopper-side locking portions 71 protrude from each other from the pair of second arm portions 65 on opposite sides in the direction of the rotation axis X. By providing two stopper-side locking portions 71 on one document stopper 60, a pair of document stoppers 60 positioned on the rear and front sides in the width direction X (rotation axis direction X) of the roller holder 44 can be used as common parts. In the document stopper 60 locked in the restricting position, the pair of second arm portions 65 are inclined diagonally upward to the left with respect to the horizontal line β at a predetermined inclination angle θ (for example, 30° to 50°), and in this embodiment, the inclination angle θ is approximately 40°.

[0041] Returning to Figures 5 to 7, the pair of document stoppers 60, positioned on the rear and front sides in the width direction X (rotation axis direction X) of the roller holder 44, are rotatably supported by support members 42 formed similarly to the multiple guide ribs 41 provided inside the opening / closing member 33. Specifically, one document stopper 60 has its pair of small-diameter shaft portions 64 (hereinafter sometimes referred to as the third axis 64) rotatably supported by the pair of support members 42, and the other document stopper 60 is similarly supported. The rotation axis α1 of the pair of document stoppers 60 is located near the left side (downstream side in the document transport direction H) of the rotation axis α2 of the feed roller 46, and the rotation axis α3 of the supply roller 47 is located to the left side (downstream side in the document transport direction H) of the rotation axis α1 of the document stopper 60 (see Figure 8).

[0042] As shown in Figures 7 and 8, the lock / unlock mechanism 70 further includes a holder-side locking portion 72 provided on the roller holder 44. In this embodiment, a pair of small, piece-shaped holder-side locking portions 72 are provided projecting upward from the outer surface on the rear side and the outer surface on the front side in the width direction X of the roller holder 44. As will be described in detail below, the pair of holder-side locking portions 72 lock or unlock to a pair of stopper-side locking portions 71 in conjunction with the rotation of the roller holder 44 around the rotation axis α3 of the first shaft 43.

[0043] As shown in Figures 7 and 8, when the roller holder 44 is in the raised position (standby position), the holder-side locking portion 72 of the lock / unlock mechanism 70 is locked to the stopper-side locking portion 71 at the upper right position (upstream side in the document transport direction H). In this locked state, the stopper piece 63 of the document stopper 60 is restricted from rotating downstream in the document transport direction H, and the leading edge Ga of the document G (for example, a bundle of documents G) on the document placement section 31 is restricted (aligned) to a restricted position by the stopper piece 63 so as not to move downstream in the document transport direction H. In other words, the document stopper 60 is locked by the locking state of the holder-side locking portion 72 and the stopper-side locking portion 71. When the roller holder 44 is in the raised position (standby position), the vertical distance L from the placement surface 31a of the document placement section 31 to the feed roller 46 is at its maximum. In this case, the maximum vertical height T (thickness T) of the document G that is permitted to be placed on the document placement section 31 is smaller than the maximum distance L.

[0044] In this embodiment, the document stopper 60 is designed so that the weight of the stopper piece 63 causes the stopper piece 63 to naturally hang downward (towards the regulating position). However, in this embodiment, a rotation-preventing part 73 is provided on the support member 42 to prevent the stopper piece 63 from rotating upstream of the regulating position in the document transport direction H. That is, if the stopper piece 63 attempts to rotate upstream of the regulating position in the document transport direction H, the stopper-side locking part 71 comes into contact with the rotation-preventing part 73, preventing it from rotating.

[0045] Figure 12 is a perspective view showing the state in which the roller holder 44 of the document feeder 3 of the first embodiment is lowered. Figure 13 is a cross-sectional view from the front showing the state in which the roller holder 44 of the document feeder 3 of the first embodiment is lowered. Figure 14 is a cross-sectional view from the front showing the state in which the lock of the document stopper 60, following Figure 10, is released and the document G is transported. In Figures 12 to 14, the document stopper 60 on the front side is shown with a dashed line relative to the holder-side locking part 72 on the front side in the width direction X, in order to make the positional relationship between the stopper-side locking part 71 and the holder-side locking part 72 easier to understand. Also, Figures 12 to 14 illustrate the case in which a number of documents G less than or equal to the stacking capacity is placed on the document placement section 31.

[0046] As shown in Figures 12 and 13, when the drive motor 50 (see Figure 3) is driven, the roller holder 44 rotates downward (in the forward rotation direction Ra) around the rotation axis α3, and the paper feed roller 46 rotates in the forward rotation direction Ra around the rotation axis α2 while rotating downward (in the forward rotation direction Ra) around the rotation axis α3. At this time, the holder-side locking part 72 also rotates downward (in the forward rotation direction Ra) around the rotation axis α3. As a result, the holder-side locking part 72 separates from the stopper-side locking part 71, the locking state between the holder-side locking part 72 and the stopper-side locking part 71 is released, and the locked state of the document stopper 60 is released (see Figure 13).

[0047] As shown in Figures 12 to 14, when the feed roller 46 descends while rotating in the forward rotation direction Ra, it contacts the uppermost document Gu in the stack of documents G on the document placement section 31, and feeds the uppermost document Gu in the document transport direction H. Then, the leading edge Ga of the uppermost document Gu pushes the stopper piece 63 of the document stopper 60 in the document transport direction H, causing the stopper piece 63 to rotate in the forward rotation direction Rc about the rotation axis α1. At this time, the stopper-side locking portion 71 rotates in the forward rotation direction Rc above the holder-side locking portion 72. The uppermost document Gu is transported to the document transport path W3 by the feed roller 46 and the supply roller 47, and during this time, the lower end of the stopper piece 63 slides against the upper surface of the uppermost document Gu. In this way, the topmost document Gu of the stack of documents G is sequentially transported to the document transport path W3, and the lower end of the stopper piece 63 slides against the upper surface of the sequentially transported documents G. At this time, the stopper piece 63 of the document stopper 60 has moved to the release position.

[0048] Incidentally, if the number of documents placed on the document placement section 31 exceeds the stacking capacity, when the documents G are sent to the document transport path W3 by the call roller 46, there is a tendency for the documents to jam in the document transport path W3. Therefore, in the document transport operation described above, if the number of documents G exceeding the stacking capacity is placed on the document placement section 31, the document feeder 3 of this embodiment is configured such that even if the drive motor 50 (see Figure 3) is driven and the call roller 46 rotates in the forward rotation direction Ra to try to pick up the document Gu at the uppermost position, the locked state of the document stopper 60 is not released.

[0049] To explain in more detail, the lock will not be released from the locked state of the document stopper 60 shown in Figure 8 to the released state of the document stopper 60 shown in Figure 13 unless the holder-side locking part 72 descends to a position lower than the stopper-side locking part 71. In other words, the lock / release mechanism 70 keeps the document stopper 60 locked in the restricted position when the vertical distance L from the placement surface 31a of the document placement section 31 to the feed roller 46 exceeds a predetermined value (the stopper-side locking part 71 cannot rotate over the holder-side locking part 72), and releases the lock when the distance L falls below the predetermined value (the stopper-side locking part 71 can rotate over the holder-side locking part 72). This predetermined value of distance L is the allowable stacking capacity of documents G that are permitted to be placed on the document placement section 31, that is, the vertical height T (thickness T) of the stack of documents G when the maximum allowable stacking capacity is placed on the document placement section 31. Therefore, when the maximum allowable stack of documents G is placed on the document placement section 31, and the feed roller 46 descends to the uppermost document G in the stack, the lock on the document stopper 60 is released. The unlocked state continues until the number of documents G falls below the maximum allowable stack and there are no documents G left.

[0050] On the other hand, the document stopper 60 is not released when the lower end of the feed roller 46 has not yet reached the height T (thickness T) of the document G at the maximum allowable limit (when the distance L is greater than a predetermined value). Therefore, if a stack of documents G exceeding the maximum allowable limit is placed on the document placement section 31, the document stopper 60 remains locked even when the lower end of the feed roller 46 descends to the uppermost document Gu, preventing the feed roller 46 from transporting the documents G to the document transport path W3. In this embodiment, when such a situation occurs, even though the feed roller 46 is rotating, the movement of the documents G in the document transport direction H is restricted by the stopper piece 63, so the feed roller 46 slides and spins freely on the upper surface of the uppermost document Gu. Furthermore, in this case, if the feed roller 46 continues to spin idly for a certain period of time (for example, about 1 to 3 seconds), the control unit 90 (see Figure 17), which will be described later, will stop the drive motor 50 and display on the operation display unit 91 that a document G exceeding the maximum allowable amount is placed on the document placement unit 31, or in addition, the lamp on the operation display unit 91 may flash to alert the user. In this case, for example, if the document detection sensor provided on the document transport system 36 (see Figure 1) does not detect the document G within a predetermined period of time (for example, about 1 to 3 seconds) from the start of operation of the drive motor 50, the control unit 90 will determine that the feed roller 46 has been spinning idly for a certain period of time. Setting the distance L to a predetermined value is possible by adjusting the ease of engagement and disengagement between the holder-side locking part 72 and the stopper-side locking part 71 by adjusting the vertical dimension J (see Figure 8) of the holder-side locking part 72. In other words, the longer the vertical dimension J of the holder-side locking portion 72 is made upward, the more difficult it becomes for the stopper-side locking portion 71 to detach from the holder-side locking portion 72. This allows the maximum allowable amount of the document G on the document placement portion 31 to be reduced (the allowable height T of the document G can be set lower).

[0051] By the way, when the upper unit 39, which is in the open state as shown in Figure 3, is closed as shown in Figures 2 and 7, the driven gear 51b may spontaneously rotate slightly (for example, by about 0.5 to 1 tooth) in the forward rotation direction Ra due to the collision when the driven gear 51b meshes with the drive gear 51a. Then, due to this slight spontaneous rotation of the driven gear 51b, the roller holder 44 and the holder-side locking part 72 also rotate (down) slightly in the forward rotation direction Ra, causing the holder-side locking part 72 to disengage from the stopper-side locking part 71, and releasing the lock on the document stopper 60, which was locked in the restricting position. In this case, when the user places a document G on the document placement section 31, a problem occurs in which the leading edge of the document G moves further towards the document transport direction H than the normal restricting position. In the document feeder 3 of this embodiment, in order to prevent such a situation, the aforementioned distance L is set to a predetermined value such that it is slightly lower than the height T of the document loading capacity G, thereby preventing unintended unlocking of the document stopper 60 due to the natural rotation of the driven gear 51b.

[0052] Furthermore, the document feeder 3 of this embodiment is designed to prevent the following problems. Specifically, as shown in Figure 3, when the opening / closing member 33 is opened from the closed state, and the connection to the transmission path of rotational driving force to the feed roller 46 is interrupted, it is assumed that the feed roller 46 (roller holder 44) will naturally rotate downward (in the forward rotation direction Ra) due to its own weight, and the document stopper 60 will return from the release position to the regulated position. In this case, if the document G becomes jammed, and the opening / closing member 33 is closed without removing the jammed document G, the lower end of the stopper piece 63 of the document stopper 60 (see Figure 8) will be pressed against the document G from above, potentially damaging the document G. Therefore, in this embodiment, a biasing member 74 (see Figures 4, 7, and 8) is provided to prevent the feed roller 46 (roller holder 44) from naturally rotating downward (in the forward rotation direction Ra) due to its own weight when the opening / closing member 33 is opened.

[0053] In this embodiment, the biasing member 74 is a tension coil spring, one end 74a of the biasing member 74 is locked to a locking portion 75 provided at the end of the roller holder 44 on the rotation axis α3 side, and the other end 74b of the biasing member 74 is locked to a locking portion 76 provided at the left end of the opening / closing member 33. In this configuration, even if the opening / closing member 33 is opened and the connection to the transmission path of rotational driving force to the drawing roller 46 is interrupted, the biasing member 74 biases the roller holder 44 so that the drawing roller 46 can maintain its raised position, thereby maintaining the raised position of the drawing roller 46, and consequently, the restriction on the rotation of the document stopper 60 from the release position to the restricted position is not released.

[0054] Figure 15 is a front-view cross-sectional view showing the document detection unit 80 in the document feeder 3 of the first embodiment. Figure 16 is a front-view cross-sectional view showing the state in which the document detection unit 80, following Figure 15, has detected a document G. Figure 17 is a schematic block diagram showing the system configuration of the control unit 90 in the document feeder 3 of the first embodiment. The document feeder 3 of this embodiment is equipped with a document detection unit 80 (document detection sensor) that detects whether or not a document G is placed on the document placement unit 31. The document detection unit 80 is provided on the lower surface of the opening / closing member 33 in the document feeder 3.

[0055] The document detection unit 80 comprises a detection unit 81 and a transmissive optical sensor 82. The detection unit 81 has a rotating shaft 81a that rotates around a rotation axis along the width direction X (the rotation axis α2 of the feed roller 46), a document contact arm 81b provided on the rotating shaft 81a that contacts the leading edge Ga of the document G on the document placement unit 31, and a sensor light shielding unit 81c provided on the rotating shaft 81a that is detected by the transmissive optical sensor 82.

[0056] The transmissive light sensor 82 has a light-emitting unit and a light-receiving unit that receives light from the light-emitting unit. When the light-receiving unit receives light from the light-emitting unit, the transmissive light sensor 82 transmits a light-receiving signal to the control unit 90, and when the light from the light-emitting unit is blocked by the sensor light-shielding unit 81c and the light-receiving unit does not receive light, it transmits a non-receiving signal to the control unit 90.

[0057] As shown in Figure 15, the document detection unit 80 is configured such that when a document G is not placed on the document placement unit 31, the document contact arm 81b contacts the document placement unit 31 by its own weight, and the sensor light shielding part 81c does not shield the transmissive optical sensor 82. At this time, a light reception signal is transmitted from the transmissive optical sensor 82 to the control unit 90. Furthermore, in the document detection unit 80, as shown in Figure 16, when a document G is placed on the document placement unit 31 and the leading edge Ga of the document G is pushed toward the document transport direction H, the leading edge Ga of the document G pushes the document contact arm 81b, causing it to rotate against its own weight, and thereby the sensor light shielding part 81c shields the transmissive optical sensor 82. At this time, a non-receiving signal is transmitted from the transmissive optical sensor 82 to the control unit 90. As the leading edge Ga of the document G is pushed further in the document transport direction H, the stopping piece 63 of the document stopper 60 restricts the leading edge Ga of the document G to a restricted position.

[0058] The document detection unit 80 (transmissive light sensor 82) is connected to the input system of the control unit 90 and transmits a light reception signal (non-document detection signal) and / or a non-light reception signal (document detection signal) to the control unit 90. As a result, the control unit 90 can detect whether or not a document G is placed on the document placement unit 31 based on the presence or absence of the non-document detection signal and / or document detection signal from the document detection unit 80.

[0059] As shown in Figures 1 and 17, the image forming apparatus 1 comprises a control unit 90 and an operation display unit 91. The control unit 90 has a processing unit 90a consisting of a microcomputer such as a CPU, and a storage unit 90b including non-volatile memory such as ROM and volatile memory such as RAM. The control unit 90 controls the operation of various components by having the processing unit 90a load a control program pre-stored in the ROM of the storage unit 90b onto the RAM of the storage unit 90b and execute it.

[0060] The operation display unit 91 is located on the front side of the image reading device 2. The operation display unit 91 is connected to the input system of the control unit 90 and receives user operation information (operation data), and outputs the received operation information to the control unit 90. This allows the control unit 90 to recognize the operation information from the operation display unit 91. The operation display unit 91 is also connected to the output system of the control unit 90 and displays various information based on the display information (display data) output from the control unit 90.

[0061] As shown in Figures 3 and 17, the drive motor 50 is connected to the output system of the control unit 90 and receives a drive signal from the control unit 90. This allows the control unit 90 to rotate the drive motor 50 at a predetermined timing.

[0062] As shown in Figures 15 to 17, the control unit 90 enables the drive motor 50 based on a non-received signal (document detection signal) and / or a non-received signal (document detection signal) from the document detection unit 80 that detects a document G on the document placement unit 31, and stops the drive motor 50 based on a received signal (non-placed document detection signal) and / or a non-received signal (document detection signal) from the document detection unit 80 that does not detect a document G on the document placement unit 31. Of course, it is also possible to control the enable and stop states of the drive motor 50 based on only one of the non-received signal (document detection signal) or non-received signal (document detection signal). Therefore, when no document G is placed on the document placement unit 31, if the user attempts to perform a copy operation using the operation display unit 91, it is possible to display a message such as "Please place a document on the document placement unit" on the operation display unit 91.

[0063] (Second Embodiment) Figure 18 is a cross-sectional view from the front showing the state in which the roller holder 44 of the opening / closing member of the document feeder 3 of the second embodiment is raised. In Figure 18, elements similar to those in Figure 8 are denoted by the same reference numerals. In the lock / unlock mechanism 170 of the second embodiment, the holder-side locking portion 172 is rotatable together with the roller holder 44 about the rotation axis α3 of the first axis, similar to the first embodiment, and has a contact surface 172a that contacts the stopper-side locking portion 71 when locked with the stopper-side locking portion 71. Furthermore, in the case of the second embodiment, this contact surface 172a is formed in the shape of a concave curved arc along a virtual circle C centered on the rotation axis α3 of the first axis. In the second embodiment, the other configurations are generally the same as those of the first embodiment.

[0064] In this configuration, when the holder-side locking portion 172 rotates together with the roller holder 44 around the rotation axis α3 of the first shaft, the contact surface 172a of the holder-side locking portion 172 moves along the arc-concave curved surface, and the stopper-side locking portion 71 can slide against the arc-concave curved surface which is the contact surface 172a. As a result, while the stopper-side locking portion 71 and the rotating holder-side locking portion 172 are locked together, the stopper-side locking portion 71 is maintained in approximately the same position. In the first embodiment, since the contact surface of the holder-side locking portion 72 is flat (see Figure 8), the stopper-side locking portion 71 tends to move slightly compared to the second embodiment while the stopper-side locking portion 71 and the rotating holder-side locking portion 72 are locked together, but this does not pose a particular problem.

[0065] (Third embodiment) Figure 19 is a schematic cross-sectional view from the front showing the placed document detection unit 180 in the document feeder of the third embodiment. Figure 20 is a schematic cross-sectional view from the front showing the state in which the placed document detection unit 180, following Figure 19, has detected a placed document. Note that in Figures 19 and 20, the same reference numerals are used for elements that are the same as those in Figures 15 and 16. In the document feeder 300 of the third embodiment, the placed document detection unit 180 is configured to detect not only the presence or absence of a document G (in this case, a stack of documents G) placed on the placement surface 31a of the document placement unit 31, but also the height T (or thickness T) of the document.

[0066] The document detection unit 180 of the third embodiment has the same configuration as the document detection unit 80 of the first embodiment, plus a second transmissive optical sensor 181. The second transmissive optical sensor 181 has a light-emitting unit and a light-receiving unit that receives light from the light-emitting unit. When the light-receiving unit receives light from the light-emitting unit, the second transmissive optical sensor 181 transmits a light-receiving signal to the control unit 90, and when the light from the light-emitting unit is blocked by the sensor light-shielding unit 81c and the light-receiving unit does not receive light, it transmits a non-receiving signal to the control unit 90. Note that the other configurations of the document detection unit 180 are the same as those of the document detection unit 80 of the first embodiment, so their description is omitted.

[0067] According to the third embodiment of the document detection unit 180, by using two sensors, a first transmissive optical sensor 82 and a second transmissive optical sensor 181, it is possible to detect not only the presence or absence of a document G (in this case, a stack of documents G) placed on the document placement unit 31, but also the height T (or thickness T) of the document. That is, as shown in Figure 19, when no document is placed on the document placement unit 31, the document contact arm 81b contacts the document placement unit 31 by its own weight, and the sensor light shielding unit 81c does not shield the first transmissive optical sensor 82 but shields the second transmissive optical sensor 181. At this time, the control unit 90 receives a light reception signal from the first transmissive optical sensor 82 and a non-receiving signal from the second transmissive optical sensor 181, and the control unit 90 determines that no document G is placed on the document placement unit 31 and maintains the drive motor 50 in a stopped state (see Figure 17).

[0068] As shown in Figure 20, when an amount of documents G exceeding the stacking capacity is placed on the document placement section 31, and the leading edge Ga of the documents G is pushed toward the document transport direction H, the document contact arm 81b is pushed by the leading edge Ga of the documents G and rotates against its own weight, causing the sensor light shielding section 81c to shield the first transmissive light sensor 82 but not the second transmissive light sensor 181. At this time, the control unit 90 receives a non-receiving signal from the first transmissive light sensor 82 and a receiving signal from the second transmissive light sensor 181, and the control unit 90 determines that an amount of documents G exceeding the stacking capacity (height T or thickness T) has been placed on the document placement section 31, and maintains the drive motor 50 in a stopped state. With this configuration, when an amount of documents G exceeding the stacking capacity is placed on the document placement section 31, even if the user inputs a copy operation using the operation display section 91, the call roller 46 will not descend to call up the document G at the uppermost position. As the leading edge Ga of the document G is pushed further in the document transport direction H, the stopping piece 63 of the document stopper 60 restricts the leading edge Ga of the document G to a restricted position.

[0069] Furthermore, if an amount of documents G exceeding the stacking capacity is placed on the document placement section 31, the control unit 90 may display a message on the operation display unit 91 informing the user that the amount of documents G on the document placement section 31 exceeds the stacking capacity. This allows the user to recognize that the amount of documents G on the document placement section 31 exceeds the stacking capacity and to place documents G on the document placement section 31 in an amount less than or equal to the stacking capacity. When an amount of documents G less than or equal to the stacking capacity is placed on the document placement section 31 (not shown), the sensor light shielding section 81c shields both the first transmissive light sensor 82 and the second transmissive light sensor 181. At this time, the control unit 90 receives non-receiving signals from the first transmissive light sensor 82 and the second transmissive light sensor 181, respectively, and the control unit 90 determines that an amount of documents G less than or equal to the stacking capacity (height T or thickness T) has been placed on the document placement section 31, and sets the drive motor 50 to a driveable state.

[0070] (Other embodiments) In the document feeding devices of the first to third embodiments, a document jam detection unit may be provided in the document transport path W3 to detect a jam in the document G, and the document jam detection unit may detect the document G jammed in the document transport path W3. Furthermore, in this case, the control unit 90 may maintain the drive motor 50 in a stopped state based on the signal from the document jam detection unit and display a message on the operation display unit 91 informing the user that a document G is jammed in the document transport path W3.

[0071] Preferred embodiments of the present invention include combinations of any of the embodiments described above. In addition to the embodiments described above, various modifications of the present invention are possible. These modifications should not be considered outside the scope of the present invention. The present invention should encompass all variations within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0072] 1: Image forming apparatus, 2: Image reading apparatus, 3,300: Document feeder, 4: Exposure apparatus, 5: Developing apparatus, 6: Photoreceptor drum, 7: Cleaning apparatus, 8: Charging apparatus, 9: Primary transfer apparatus, 9a: Drive roller, 9b: Driven roller, 9c: Intermediate transfer belt, 10: Image forming apparatus main body, 11: Image forming section, 12: Paper transport section, 13: Secondary transfer apparatus, 13a: Secondary transfer roller, 14: Fixing apparatus, 14a: Heat roller, 14b: Pressure roller, 15: Paper feed tray, 16: Manual feed tray, 17: Discharge roller, 18: Discharge tray, 19a,19b: Pickup roller, 20a: Transport roller, 20b: Reversing transport roller, 21: Register roller, 22: Document placement table, 23: Document reading plate section 24: Image sensor, 25: Image reading unit, 26: Housing, 31: Document placement unit, 31a: Placement surface, 32: Document supply unit, 33: Opening / closing member, 34: Document ejection unit, 35: Document transport roller, 36: Document transport system, 37: Guide member, 38: Lower unit, 39: Upper unit, 40: Rotating shaft, 41: Guide rib, 42: Support member, 43: First shaft, 44: Roller holder, 45: Second shaft, 46: Entry roller, 47: Supply roller, 48: Separation pad, 50: Drive motor, 51: Power transmission mechanism, 51a: Drive gear, 51b: Driven gear, 52: Torque limiter, 53: Drive timing pulley, 54: Driven timing pulley, 55: Timing belt, 56: First one-way clutch, 57: Second one-way clutch, 58: Second shaft, 59: Limiter coupling, 60: Document stopper, 61: Large diameter shaft section, 62: First arm section, 63: Stopper piece section, 64: Small diameter shaft section (third shaft), 65: Second arm section, 70,170: Lock / release mechanism, 71: Stopper side locking section, 72,172: Holder side locking section, 73: Rotation stopper section, 74: Biasing member, 74a: One end, 74b: Other end, 75,76: Locking section, 80,180: Document detection unit, 81: Detected unit, 81a: Rotation axis, 81b: Document contact arm, 81c: Sensor light shielding unit, 82: Transmissive light sensor (first transmissive light sensor), 181: Second transmissive light sensor, 90: Control unit, 90a: Processing unit, 90b: Memory unit, 91: Operation display unit, C: Virtual circle, E: Rotation direction, F: Marker, G, Gu: Document, Ga: Front end, H: Document transport direction, J: Dimensions, L: Distance, P: Paper, Ra: Forward rotation direction, Rb: Reverse rotation direction, Rc: Forward rotation direction, T: Height, Thickness, W1: Paper transport path, W2: Reversing paper transport path, W3: Document transport path, X: Width direction (front / back direction, rotation axis direction), Y: Left / right direction, Z: Up / down direction (vertical direction) α1: Rotation axis, α2, α3: axis of rotation,

Claims

1. It comprises a document placement section on which a document can be placed, a document transport path on which the document is transported, and a document supply section that supplies the document placed in the document placement section to the document transport path. The document supply unit comprises a support member, a roller holder rotatably attached to the support member via a first axis, a retrieval roller rotatably attached to the roller holder via a second axis to send the document placed on the document placement unit to the document transport path, a document stopper rotatably attached to the support member via a third axis, and a lock / release mechanism. The document stopper is rotatable between a restricting position that restricts the supply of the document to the document transport path and a release position that releases the restriction on the document to the document transport path. The locking and unlocking mechanism is configured to switch between a locked state, in conjunction with the rotational movement of the roller holder, which locks the document stopper in the restricting position, and an unlocked state, which releases the lock and allows the document stopper to rotate to the restricted release position.

2. The document feeding device according to claim 1, wherein the locking and unlocking mechanism locks the document stopper to the restricting position when the vertical distance from the placement surface of the document placement section to the feed roller exceeds a predetermined value due to the rotational operation of the roller holder, and unlocks the document when the distance becomes less than or equal to the predetermined value.

3. The document feeding device according to claim 2, wherein the predetermined value is the maximum vertical height from the aforementioned surface of the document that can send the uppermost document among those placed on the aforementioned surface of the document placement section to the document transport path without causing a paper jam by the paper intake roller.

4. The locking and unlocking mechanism has a holder-side locking portion provided on the roller holder and a stopper-side locking portion provided on the document stopper. The document feeding device according to claim 1, wherein the holder-side locking portion and the stopper-side locking portion are locked together to achieve the locked state, and the unlocked state is achieved when the locking between the holder-side locking portion and the stopper-side locking portion is released.

5. The locking and unlocking mechanism has a holder-side locking portion provided on the roller holder and a stopper-side locking portion provided on the document stopper. The document feeding device according to claim 1, wherein, due to the rotational operation of the roller holder, when the vertical distance from the placement surface of the document placement section to the document feeding roller exceeds a predetermined value, the holder-side locking portion and the stopper-side locking portion engage, locking the document stopper in the restricting position, and when the distance becomes less than or equal to the predetermined value, the engagement between the holder-side locking portion and the stopper-side locking portion is released, thereby releasing the lock.

6. The document feeding device according to claim 5, wherein the predetermined value is the maximum vertical height from the aforementioned placement surface of the document at the uppermost position among the documents placed on the aforementioned placement surface of the document placement section, so that the document at the uppermost position can be sent to the document transport path by the intake roller without causing a paper jam.

7. The holder-side locking portion is rotatable together with the roller holder about the first axis and has a contact surface that contacts the stopper-side locking portion when locked with the stopper-side locking portion. The document feeding device according to claim 5, wherein the contact surface is formed in the shape of a concave curved arc along a virtual circle centered on the first axis.

8. The system further comprises a drive mechanism that raises and lowers the intake roller by rotating the roller holder, The drive mechanism comprises a drive motor and a power transmission mechanism that transmits rotational force from the output shaft of the drive motor to the pull-in roller. The document feeding device according to claim 1, wherein the power transmission mechanism rotates the roller holder downward by the rotational force from the output shaft to lower the feed roller.

9. The document supply unit comprises a lower unit having the support member and an upper unit rotatably attached to the lower unit so as to be openable and closable. The lower unit has the drive motor, The upper unit comprises the roller holder, the drawing roller, the document stopper, and the lock / release mechanism. The power transmission mechanism includes a drive gear fixed to the output shaft of the drive motor and provided on the lower unit, and a driven gear provided on the upper unit so as to be able to mesh with the drive gear. The document feeding device according to claim 8, wherein the lock / unlock mechanism is adjusted so that the lock of the document stopper is not released when the driven gear rotates naturally downward due to the natural rotation of the driven gear when the upper unit is moved from an open state to a closed state and the driven gear is engaged with the drive gear.

10. The document feeding device further comprises a document detection unit capable of detecting a document on the document placement unit, The document feeding device according to claim 1, wherein the drive mechanism becomes drivable when the document detection unit detects a document on the document placement unit, and the drive mechanism becomes stopped when the document detection unit does not detect a document on the document placement unit.

11. The document placement detection unit is capable of detecting the vertical height of the document on the document placement unit. The document feeding device according to claim 10, wherein the drive mechanism becomes drivable when the height of the document detected by the document detection unit is less than or equal to a predetermined value, and the drive mechanism becomes stopped when the height of the document detected by the document detection unit exceeds a predetermined value.

12. An image forming apparatus comprising: a document reading device; a document feeding device according to any one of claims 1 to 11 for feeding a document to the document reading device; and an image forming apparatus main body for forming an image on a sheet-like recording medium based on image data of a document read by the document reading device.

13. The image forming apparatus body further includes a control unit that controls the drive mechanism based on a signal from the previously described document detection unit, The image forming apparatus according to claim 12, referencing claim 10, wherein the control unit enables the drive mechanism to be driven based on a signal from the aforementioned document placement detection unit that detects a document on the document placement unit, and stops the drive mechanism based on a signal from the aforementioned document placement detection unit that does not detect a document on the document placement unit.

14. The document placement detection unit is capable of detecting the vertical height of the document on the document placement unit. The image forming apparatus according to claim 13, wherein the drive mechanism becomes drivable when the height of the document detected by the document detection unit is less than or equal to a predetermined value, and the drive mechanism becomes stopped when the height of the document detected by the document detection unit exceeds a predetermined value.

15. The image forming apparatus body has an operation display unit, The image forming apparatus according to claim 14, wherein the control unit causes the operation display unit to display a message to the user informing them that the number of documents on the document placement unit exceeds the stacking capacity, based on a signal from the document placement unit that has detected a document with a height exceeding the predetermined value.

Images