Automatic document transport device, image forming apparatus, and transport method

Abstract

The present invention provides an automatic document transport device, an image forming apparatus, and a transport method that can determine whether the document has been removed from the loading platform by the user or whether the document has moved away from its loading position on the loading platform. [Solution] An automatic document transport device that automatically transports a document to the reading position of an image reader, comprising: a first detection unit that detects when the document is placed on the placement position of the document placement table; a second detection unit positioned upstream of the first detection unit in the document transport direction and detecting the passage of the trailing end of the document when the document is transported from the document placement table; a paper feed control unit that controls the paper feeding operation of the document placed on the document placement table; and a determination unit that, when the paper feeding operation of the document is started by the paper feed control unit, determines whether the document has been pulled out, whether the document has moved away from the previously placed position, or whether the document is properly placed in the previously placed position, according to the detection results of the first detection unit and the second detection unit.

Description

Technical Field

[0001] The present invention relates to an automatic document feeder, an image forming apparatus, and a conveying method.

Background Art

[0002] There is known a technique related to an automatic document feeder that stops when a conveyance abnormality is detected during document conveyance.

[0003] As a technique related to such an automatic document feeder, in order to continue the conveyance of a document when the document pulled out from a placement table is placed again, a technique for determining the re-placement after the pulling out of the document from sensor information and an internal flag is known (for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there has been a problem that it is impossible to determine whether the document has been pulled out from the placement table by the user or has deviated from the set position of the placement table.

[0005] The present invention has been made in view of the above, and an object thereof is to provide an automatic document feeder, an image forming apparatus, and a conveying method capable of determining whether a document has been pulled out from a placement table by a user or has deviated from the placement position of the placement table.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the present invention provides an automatic document transport device that automatically transports a document to the reading position of an image reader, comprising: a first detection unit that detects when the document is placed on the placement position of the document placement table; a second detection unit that is positioned upstream of the first detection unit in the document transport direction and detects when the document is transported from the document placement table and the trailing edge of the document has passed; a paper feed control unit that controls the paper feeding operation of the document placed on the document placement table; and a determination unit that, when the paper feeding operation of the document is started by the paper feed control unit, determines whether the document has been pulled out, whether the document has moved away from the previously described placement position, or whether the document is properly placed in the previously described placement position, according to the detection results of the first detection unit and the second detection unit. [Effects of the Invention]

[0007] According to the present invention, it is possible to determine whether the user has removed the document from the tray or whether the document has moved away from its position on the tray. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows an example of the overall configuration of an image forming apparatus according to an embodiment. [Figure 2] Figure 2 shows an example of a part of the configuration of the image forming section of an image forming apparatus according to an embodiment. [Figure 3] Figure 3 shows an example of a part of the configuration of the tandem section of the image forming unit of the image forming apparatus according to the embodiment. [Figure 4] Figure 4 is a perspective view of the scanner and ADF of the image forming apparatus according to the embodiment. [Figure 5] Figure 5 is a cross-sectional view showing an example of the configuration of the ADF in an image forming apparatus according to an embodiment. [Figure 6] Figure 6 is a perspective view of the ADF of the image forming apparatus according to the embodiment. [Figure 7] Figure 7 is an external perspective view of the document set sensor mounted in the image forming apparatus according to this embodiment. [Figure 8]Figure 8 illustrates the detection operation of the edges of a document by a document set sensor in an image forming apparatus according to an embodiment. [Figure 9] Figure 9 shows an example of the hardware configuration of an image forming apparatus according to an embodiment. [Figure 10] Figure 10 shows an example of a functional block of an image forming apparatus according to an embodiment. [Figure 11] Figure 11 shows an example of the arrangement of a rear-end detection sensor and a sensor for detecting the size of a document in an ADF according to the embodiment. [Figure 12] Figure 12 is a flowchart showing the flow of a conventional document feeding operation. [Figure 13] Figure 13 is a flowchart showing an example of the document feeding operation of the ADF according to this embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the automatic document transport apparatus, image forming apparatus, and transport method according to the present invention will be described in detail below with reference to the drawings. Furthermore, the present invention is not limited by the following embodiments, and the components in the following embodiments include those that are easily conceivable by those skilled in the art, those that are substantially the same, and those that are equivalent. Moreover, various omissions, substitutions, modifications, and combinations of components can be made without departing from the spirit of the following embodiments.

[0010] (Configuration of an image forming apparatus) Figure 1 shows an example of the overall configuration of an image forming apparatus according to the embodiment. Figure 2 shows an example of a part of the configuration of the image forming section of the image forming apparatus according to the embodiment. Figure 3 shows an example of a part of the configuration of the tandem section of the image forming section of the image forming apparatus according to the embodiment. The configuration of the image forming apparatus 100 according to this embodiment will be described with reference to Figures 1 to 3. Note that the four imaging units 3K, 3Y, 3M, and 3C have almost the same configuration except for the different toner colors they use, and are therefore referred to as imaging unit 3 in Figure 3.

[0011] As shown in Figure 1, the image forming apparatus 100 comprises an image forming unit 1, a sheet supply device 40, and an image reading system 50. The image reading system 50 includes a scanner 150, which serves as an image reading device fixed on the image forming unit 1, and an ADF (Automatic Document Feeder) 51 supported by it.

[0012] The sheet supply device 40 includes two paper feed cassettes 42 arranged in multiple stages within the paper bank 41, a feed roller 43 that feeds recording sheets from the paper feed cassettes 42, and a separation roller 45 that separates the fed recording sheets one by one and transports them to the feed path 44. The sheet supply device 40 also has multiple pairs of transport rollers 46 on the feed path 44 that transport recording sheets to the paper feed path 37, which serves as the transport path for the image forming unit 1.

[0013] The paper feed cassette 42 is a cassette that houses a stack of multiple recording sheets. The paper feed cassette 42 presses the feed roller 43 against the top recording sheet. When the feed roller 43 rotates, the top recording sheet of the sheet stack is fed out of the paper feed cassette 42.

[0014] In the supply path 44, a conveying nip is formed when the first conveying roller of the conveying roller pair 46 and the second conveying roller, which is located to the side of the first conveying roller (to the right in Figure 1), come into contact with each other. Furthermore, a separating roller 45 is located below the first conveying roller and comes into contact with the first conveying roller from below, forming a separating conveying nip.

[0015] The recording sheet fed out from the paper feed cassette 42 by the rotational drive of the delivery roller 43 enters the separation conveyance nip formed by the contact between the first conveyance roller of the conveyance roller pair 46 and the separation roller 45 disposed below it. The separation conveyance nip applies a conveyance force to the recording sheet from the paper feed cassette 42 side toward the feed path 44 side while the first conveyance roller that contacts the upper surface of the recording sheet is rotationally driven in the counterclockwise direction in the plane of FIG. 1. On the other hand, the separation roller 45 that contacts the lower surface of the recording sheet applies a conveyance force to the recording sheet from the feed path 44 side toward the paper feed cassette 42 side while rotationally driven in the counterclockwise direction in the plane of FIG. 1, attempting to return the recording sheet to the paper feed cassette 42.

[0016] Also, when the recording sheet is fed out from the paper feed cassette 42 in a state where only one sheet is present, the separation conveyance nip applies conveyance forces in opposite directions to the recording sheet by the first conveyance roller and the separation roller 45. As a result, a load exceeding a predetermined threshold is applied to the drive transmission system of the separation roller 45. Then, the torque limiter disposed within the drive transmission system operates to cut off the transmission of the driving force from a DC brushless motor (not shown) to the separation roller 45. Thereby, the separation roller 45 comes to be carried along with the recording sheet conveyed by the first conveyance roller, and the recording sheet is discharged from the separation conveyance nip toward the feed path 44.

[0017] On the other hand, when the recording sheets are fed out from the paper feed cassette 42 in a state where a plurality of sheets are stacked, in the separation conveyance nip, the first conveyance roller applies a conveyance force to the topmost recording sheet from the paper feed cassette 42 side toward the feed path 44 side. Then, the topmost recording sheet is sent out from the separation conveyance nip toward the feed path 44 side. In contrast, the separation roller applies a conveyance force to the recording sheets located on the lower side from the feed path 44 side toward the paper feed cassette side, causing the lower recording sheets to reverse back from within the separation conveyance nip to the paper feed cassette 42 side. Thereby, in the separation conveyance nip, the topmost recording sheet is separated from the other recording sheets and sent out to the feed path 44 in a single-sheet state.

[0018] The recording sheet that has entered the feeding path 44 enters the conveying nip of the pair of conveying rollers 46 and is given a conveying force directed from the lower side in the vertical direction to the upper side. As a result, within the feeding path 44, the recording sheet is conveyed toward the paper feeding path 37 of the image forming unit 1.

[0019] The image forming unit 1 includes an optical writing device 2 and four image forming units 3K, 3Y, 3M, 3C for forming toner images of black (K), yellow (Y), magenta (M), and cyan (C), etc. Further, the image forming unit 1 also includes a transfer unit 24, a paper conveying unit 28, a registration roller pair 33, a fixing device 34, a switchback device 36, a paper feeding path 37, and the like. Then, the image forming unit 1 drives a light source such as a laser diode or an LED (Light Emitting Diode), not shown, disposed within the optical writing device 2, and irradiates laser light L toward the four drum-shaped photoreceptors 4K, 4Y, 4M, 4C. By this irradiation, an electrostatic latent image is formed on the surfaces of the photoreceptors 4K, 4Y, 4M, 4C, and this electrostatic latent image is developed into a toner image via a predetermined developing process.

[0020] The image forming units 3K, 3Y, 3M, 3C support the photoreceptors 4K, 4Y, 4M, 4C and various devices disposed around them as one unit on a common support, and are detachable from the main body of the image forming unit 1. As shown in FIG. 3, the image forming unit 3 has a charging device 23, a developing device 6, a drum cleaning device 15, a charge removing lamp 22, etc. around the photoreceptor 4. The image forming unit 1 has a so-called tandem type configuration in which the four image forming units 3K, 3Y, 3M, 3C are arranged opposite to each other along the endless moving direction with respect to the intermediate transfer belt 25 described later.

[0021] The photoreceptor 4 is a drum-shaped member in which a photosensitive layer is formed by applying a photosensitive organic photosensitive material to a base tube made of aluminum or the like. Note that an endless belt-shaped photoreceptor 4 may be used.

[0022] The developing apparatus 6 is a device that develops a latent image using a two-component developer containing a magnetic carrier (not shown) and a non-magnetic toner. The developing apparatus 6 has an agitation unit 7 that transports the two-component developer contained inside while agitating it and supplies it to the developing sleeve 12, and a developing unit 11 that transfers the toner in the two-component developer supported on the developing sleeve 12 to the photoreceptor 4.

[0023] The stirring unit 7 is located at a lower position than the developing unit 11 and includes two transport screws 8 arranged parallel to each other, a partition plate provided between the transport screws 8, and a toner density sensor 10 provided on the bottom surface of the developing case 9.

[0024] The developing unit 11 includes a developing sleeve 12 that faces the photoreceptor 4 through the opening of the developing case 9, a magnetic roller 13 that is not rotatable inside the developing sleeve 12, and a doctor blade 14 that brings its tip close to the developing sleeve 12.

[0025] The developing sleeve 12 is a non-magnetic, rotatable cylindrical member. The magnetic roller 13 is a roller having multiple magnetic poles arranged sequentially from a position opposite the doctor blade 14 toward the direction of rotation of the sleeve. Each of these magnetic poles acts a magnetic force on the two-component developer on the developing sleeve 12 at a predetermined position in the direction of rotation. This attracts and supports the two-component developer sent from the agitator 7 on the surface of the developing sleeve 12, and also forms a magnetic brush along the magnetic field lines on the surface of the developing sleeve 12.

[0026] As the developing sleeve 12 rotates, the magnetic brush passes opposite the doctor blade 14, where it is restricted to an appropriate layer thickness before being transported to the developing area opposite the photoreceptor 4. There, the developing bias applied to the developing sleeve 12 and the potential difference between them and the electrostatic latent image on the photoreceptor 4 transfer the toner onto the electrostatic latent image, contributing to development. Furthermore, as the developing sleeve 12 rotates, it returns to the developing section 11, and after being separated from the surface of the developing sleeve 12 by the repulsive magnetic field formed between the magnetic poles of the magnet roller 13, it returns to the stirring section 7. In the stirring section 7, an appropriate amount of toner is supplied to the two-component developer based on the detection result from the toner concentration sensor 10. Note that instead of using a two-component developer, a one-component developer that does not contain magnetic carriers may be used as the developing device 6.

[0027] The drum cleaning device 15 is a device that uses an elastic cleaning blade 16 to press against the photoreceptor 4. The drum cleaning device 15 may be of a different type. Furthermore, to enhance cleaning efficiency, the drum cleaning device 15 has a contact-conductive fur brush 17 that contacts the photoreceptor 4, and is rotatable in the direction of the arrow shown in Figure 3. The fur brush 17 also serves to scrape off lubricant from a solid lubricant (not shown) into a fine powder and apply it to the surface of the photoreceptor 4. The drum cleaning device 15 also has a metal electric field roller 18 that applies a bias to the fur brush 17, and is rotatable in the direction of the arrow shown in Figure 3. The tip of a scraper 19 is pressed against the electric field roller 18. Toner adhering to the fur brush 17 is transferred to the electric field roller 18, which is rotating in a counter-direction relative to the fur brush 17 and to which a bias is applied. The toner is then scraped off the electric field roller 18 by the scraper 19 and falls onto the recovery screw 20. The recovery screw 20 transports the recovered toner toward the end of the drum cleaning device 15 in the direction perpendicular to the plane of the paper in Figure 3, and hands it over to an external recycling transport device. The recycling transport device sends the received toner to the developing device 6 for recycling.

[0028] The static elimination lamp 22 is a lamp that eliminates static electricity from the photoreceptor 4 by light irradiation. After the static elimination, the surface of the photoreceptor 4 is uniformly charged by the charging device 23, and then light writing is performed by the light writing device 2. The charging device 23 is subjected to a charging bias and rotates while in contact with the photoreceptor 4. Alternatively, the charging device 23 may be a non-contact charging device such as a scorotron charger.

[0029] In Figure 2, toner images of K, Y, M, and C are formed on the photoreceptors 4K, 4Y, 4M, and 4C of the four imaging units 3K, 3Y, 3M, and 3C by the process described above.

[0030] The transfer unit 24 is a unit positioned below the four imaging units 3K, 3Y, 3M, and 3C. The transfer unit 24 moves an intermediate transfer belt 25, which is stretched by multiple rollers, in an endless clockwise direction as shown in Figure 2, while keeping it in contact with the photoreceptors 4K, 4Y, 4M, and 4C. This forms primary transfer nips for K, Y, M, and C where the photoreceptors 4K, 4Y, 4M, and 4C are in contact with the endless intermediate transfer belt 25. Near the primary transfer nips for K, Y, M, and C, the intermediate transfer belt 25 is pressed toward the photoreceptors 4K, 4Y, 4M, and 4C by primary transfer rollers 26K, 26Y, 26M, and 26C, which are positioned inside the belt loop. Primary transfer biases are applied to each of these primary transfer rollers 26K, 26Y, 26M, and 26C by power supplies (not shown). As a result, a primary transfer electric field is formed in the primary transfer nip for K, Y, M, and C, which electrostatically moves the toner images on the photoreceptors 4K, 4Y, 4M, and 4C toward the intermediate transfer belt 25. As the intermediate transfer belt 25 moves endlessly in a clockwise direction as viewed on the paper in Figure 2, the toner images are sequentially superimposed and transferred onto the front surface of the intermediate transfer belt 25, passing through the primary transfer nip for K, Y, M, and C in sequence. This superimposed primary transfer forms a four-color superimposed toner image (hereinafter referred to as the four-color toner image) on the front surface of the intermediate transfer belt 25.

[0031] The image forming unit 1 has a paper transport unit 28 below the transfer unit 24, which moves an endless paper transport belt 29 between a drive roller 30 and a secondary transfer roller 31. The intermediate transfer belt 25 and the paper transport belt 29 are sandwiched between the secondary transfer roller 31 and the lower tension roller 27 of the transfer unit 24. This forms a secondary transfer nip where the front surface of the intermediate transfer belt 25 and the front surface of the paper transport belt 29 come into contact. The secondary transfer roller 31 is subjected to a secondary transfer bias by a power supply (not shown). Meanwhile, the lower tension roller 27 of the transfer unit 24 is grounded. This forms a secondary transfer electric field in the secondary transfer nip.

[0032] Furthermore, the image forming unit 1 includes a pair of resist rollers 33 located to the right of the secondary transfer nip in Figure 2, and a resist roller sensor (not shown) located near the entrance of the resist nip of the resist roller pair 33. The recording sheet, transported from the sheet supply device 40 toward the pair of resist rollers 33, pauses temporarily after a predetermined time when its leading edge is detected by the resist roller sensor, and then abuts its leading edge against the resist nip of the resist roller pair 33.

[0033] When the leading edge of the recording sheet hits the resist nip, the resist roller pair 33 restarts its roller rotation drive at a timing that allows the recording sheet to be synchronized with the four-color toner image on the intermediate transfer belt 25, and feeds the recording sheet to the secondary transfer nip. Inside the secondary transfer nip, the four-color toner image on the intermediate transfer belt 25 is transferred to the recording sheet all at once by the action of the secondary transfer electric field and nip pressure, and combined with the white of the recording sheet, it becomes a full-color image. After passing through the secondary transfer nip, the recording sheet separates from the intermediate transfer belt 25 and is held on the front surface of the paper transport belt 29, and is transported to the fixing device 34 as it moves endlessly.

[0034] The surface of the intermediate transfer belt 25, which has passed through the secondary transfer nip, has residual toner that was not transferred to the recording sheet by the secondary transfer nip. This residual toner is scraped off by a belt cleaning device that comes into contact with the intermediate transfer belt 25.

[0035] The recording sheet, transported to the fixing device 34, has a full-color image fixed by pressurization and heating within the fixing device 34. After that, it is sent from the fixing device 34 to the paper discharge roller 35 and then discharged outside the image forming unit 1.

[0036] As shown in Figure 1, the image forming unit 1 has a switchback device 36 located below the paper transport unit 28 and the fixing device 34. This allows the switching claw to switch the path of the recording sheet, after image fixing processing has been completed on one side, towards the recording sheet reversing device, where it is reversed and re-entered the secondary transfer nip. The recording sheet then undergoes secondary image transfer and fixing processing on the other side before being discharged onto the output tray.

[0037] The scanner 150, fixed on the image forming unit 1, has a movable reading unit 152. The scanner 150 and the ADF 51 each have fixed reading units. The movable reading unit 152 is positioned directly beneath a second contact glass 155 (described later), fixed to the upper wall of the scanner 150's casing so as to contact the original document MS. The optical system, consisting of a light source and reflective mirrors, can be moved in the left-right direction in Figure 1. As the optical system moves from left to right in the figure, light emitted from the light source is reflected by an original document (not shown) placed on the second contact glass 155, then passes through multiple reflective mirrors before being received by an image reading sensor 153 fixed to the scanner 150 body.

[0038] On the other hand, the fixed reading unit consists of a first fixed reading unit 151 disposed inside the scanner 150 and a second fixed reading unit 95, which will be described later, disposed inside the ADF 51. The first fixed reading unit 151, which has a light source, a reflective mirror, and an image reading sensor such as a CCD (Charge-Coupled Device), is disposed directly below a first contact glass 154, which will be described later, fixed to the upper wall of the scanner 150 casing so as to contact the original document MS. When the sheet-like original document MS transported by the ADF 51 passes over the first contact glass 154, the light emitted from the light source is sequentially reflected from the surface of the original document MS and received by the image reading sensor after passing through multiple reflective mirrors. In this way, the first surface of the original document MS is scanned without moving the optical system consisting of the light source and reflective mirrors. The second fixed reading unit 95 scans the second surface of the original document MS after it has passed through the first fixed reading unit 151.

[0039] (ADF configuration) Figure 4 is a perspective view of the scanner and ADF of the image forming apparatus according to the embodiment. Figure 5 is a cross-sectional view showing an example of the configuration of the ADF of the image forming apparatus according to the embodiment. Figure 6 is a perspective view of the ADF of the image forming apparatus according to the embodiment. Figure 7 is an external perspective view of the document set sensor mounted on the image forming apparatus according to the embodiment. Figure 8 is a diagram illustrating the detection operation of the edge of the document by the document set sensor in the image forming apparatus according to the embodiment. The configuration of the ADF 51 of the image forming apparatus 100 according to this embodiment will be described with reference to Figures 4 to 8.

[0040] As shown in Figures 4 and 6, the ADF 51, mounted on top of the scanner 150, holds a document rest 53, which is a document resting means for placing the original document MS before scanning, on the main body cover 52. The ADF 51 also holds a transport unit 54 for transporting the original document MS as a sheet material, and a document stacking table 55 for stacking the scanned original document MS. As shown in Figure 4, the ADF 51 is supported so as to be rotatable using a hinge 159 fixed to the scanner 150 as a pivot point. Through this rotational movement, the ADF 51 moves like an opening and closing door, exposing the first contact glass 154 and the second contact glass 155 on the top surface of the scanner 150 when open.

[0041] In the case of single-sided bound documents, such as books bound at one corner of the stack, the ADF 51 cannot separate the documents one by one and therefore cannot transport them. In the case of single-sided bound documents, the user opens the ADF 51 as shown in Figure 4, places the single-sided bound document with the pages to be scanned facing downwards on the second contact glass 155, and then closes the ADF 51. The moving reading unit 152 of the scanner 150 then reads the image of the page in question.

[0042] On the other hand, in the case of a stack of multiple independent original documents (MS) piled up, the ADF 51 can automatically transport the original documents one by one, sequentially scanning them with the first fixed reading unit 151 in the scanner 150 and the second fixed reading unit 95 in the ADF 51 (described later). In this case, the user places the stack of documents on the document tray 53 and then presses the start button 158 shown in Figure 4. The ADF 51 then sends the original documents (MS) from the stack placed on the document tray 53 into the transport unit 54 from top to bottom, and transports them toward the document stack tray 55 while inverting them. During this transport process, the ADF 51 passes the original documents (MS) directly above the first fixed reading unit 151 of the scanner 150 immediately after inverting them. At this time, the first side of the original documents (MS) is read by the first fixed reading unit 151 of the scanner 150.

[0043] As shown in Figure 5, the ADF 51 includes a document setting section A, a separation and feeding section B, a resist section C, a turning section D, a first reading and transport section E, a second reading and transport section F, a paper discharge section G, and a stacking section H, etc. The ADF 51 also includes a document transport path for transporting the document MS from the document placement table 53 toward the first fixed reading section 151, which is the image reading position.

[0044] The document setting unit A has a document placement table 53 on which a stack of document MSs is placed. The separation and feeding unit B separates and feeds the document MSs one by one from the stack of placed document MSs. The resist unit C temporarily abuts the fed document MSs to align them before feeding them out. The turning unit D has a curved transport unit that curves in a C shape, and within this curved transport unit the document MSs are folded and inverted. The first reading and transport unit E transports the document MSs on the first contact glass 154 and causes the first fixed reading unit 151, which is located inside the scanner 150 below the first contact glass 154, to read the first side of the document MSs. The second reading and transport unit F transports the document MSs below the second fixed reading unit 95 and causes the second side of the document MSs to be read by the second fixed reading unit 95. Furthermore, the output unit G ejects the document MS, from which images have been scanned on both sides, toward the stacking unit H. The stacking unit H then stacks the document MS on the document stacking tray 55.

[0045] The original document MS is placed on the document tray 53 so that its leading edge is detected by the document set sensor 56 (first detection unit). That is, the document set sensor 56 detects the original document MS placed in the correct position on the document tray 53. At this time, the position of the original document MS in the width direction is adjusted on the document tray 53 by side guides (not shown) being placed against both ends of the document MS in the width direction (the direction perpendicular to the paper plane in Figure 5). The document set sensor 56 then detects the placement of the original document MS and transmits a detection signal to the controller 60, which will be described later.

[0046] As shown in Figure 7, the document set sensor 56 consists of a photointerrupter 56a and a mechanical flag 56b. The photointerrupter 56a emits and receives light rays inside a U-shape, and the presence or absence of a document MS is detected when the mechanical flag 56b enters the inside of the U-shape and blocks the optical path of the light rays. The mechanical flag 56b is a component that rotates around a pivot point 56c when the document MS comes into contact with it.

[0047] As shown in Figure 8(a), when the original document MS is not in contact with the mechanical flag 56b, the mechanical flag 56b blocks the optical path of the photointerrupter 56a, and this state is determined to be "no original document". The state in which the optical path of the photointerrupter 56a is blocked by the mechanical flag 56b is referred to as the "off" state of the original document set sensor 56. Also, as shown in Figure 8(b), when the original document MS is in contact with the mechanical flag 56b, the mechanical flag 56b no longer blocks the optical path of the photointerrupter 56a, and this state is determined to be "original document present". The state in which the optical path of the photointerrupter 56a is not blocked by the mechanical flag 56b is referred to as the "on" state of the original document set sensor 56. Then, as shown in Figure 8(c), when the document MS passes the document set sensor 56, the mechanical flag 56b again blocks the optical path of the photo interrupter 56a, and the system returns to a state of no document. However, regarding the determination of the presence or absence of a document MS, when the last sheet of the document MS passes the document set sensor 56, the mechanical flag 56b may collide with the transport path and bounce, and after the last sheet has passed, the system may return to a state of having a document. Therefore, a waiting time x[s] is provided until the bouncing of the mechanical flag 56b subsides, and even if the system initially detects no document, if it detects no document again after the waiting time x[s], the state of having no document is confirmed. However, if the determination of the presence or absence of the next document MS is performed solely by the detection operation of the document set sensor 56 after one sheet of the document MS has been sent into the transport unit 54, then the system must wait for the aforementioned waiting time x[s] before feeding the next document, which does not improve productivity. Therefore, the ADF 51 is equipped with a rear-end detection sensor 58 (second detection unit) on the document placement table 53, located upstream in the transport direction from the position where the document set sensor 56 is located, to detect the presence or absence of a document MS. Specifically, the rear-end detection sensor 58 detects the passage of the rear end of a document MS when a paper feeding operation is performed on a document MS placed in the placement position. The ADF 51 uses the detection information of the presence or absence of a document MS from this rear-end detection sensor 58 to determine the presence or absence of the next document after one document MS has been fed into the transport unit 54.

[0048] Furthermore, the ADF 51 is equipped with a document length sensor 57 (third detection unit) on the document placement table 53, which consists of a reflective photosensor or an actuator-type sensor that detects the length of the document MS in the transport direction. This document length sensor 57 detects the length of the document MS in the transport direction.

[0049] Furthermore, the image forming unit 1 is equipped with a touch panel 157 that can be operated and displayed. The user can use the touch panel 157 to perform operations such as setting the reading mode, indicating whether to use double-sided or single-sided reading mode. When the user presses the start button 158, a document feed signal is sent from the main unit control unit 1a (described later) to the ADF 51 controller 60. The ADF 51 then rotates the pickup roller 80 by rotating the paper feed motor 76 (described later) in the forward direction, and feeds the document MS on the document tray 53 into the transport unit 54.

[0050] When setting whether to use double-sided or single-sided scanning mode, place the document on the document tray 53. It is possible to set the scanning mode for all placed documents (MS) at once to either double-sided or single-sided. Furthermore, it is also possible to set the scanning mode for individual documents, for example, setting the first and tenth documents to double-sided scanning mode while setting the others to single-sided scanning mode.

[0051] The original document MS, fed by the pickup roller 80, enters the separation and feeding section B and is fed to the contact position between the paper feed belt 84 and the separation roller 85. The paper feed belt 84 is stretched by a drive roller 82 and a driven roller 83, and is moved endlessly in a clockwise direction as viewed in Figure 5 by the rotation of the drive roller 82 accompanying the forward rotation of the paper feed motor 76. The separation roller 85, which is rotated clockwise as viewed in Figure 5 by the forward rotation of the paper feed motor 76, is in contact with the lower tension surface of the paper feed belt 84. At the contact point, the surface of the paper feed belt 84 moves in the paper feeding direction. In contrast, the separation roller 85 is in contact with the paper feed belt 84 with a predetermined pressure, and when it is in direct contact with the paper feed belt 84, or when only one original document MS is caught in the contact point, it moves along with the paper feed belt 84 or the original document MS. However, when multiple original documents (MS) are caught in the contact area, the accompanying force becomes lower than the torque limiter's torque. Therefore, the separation roller 85 rotates clockwise in the direction opposite to the accompanying direction, as shown in Figure 5. As a result, the original documents below the top are subjected to a moving force in the opposite direction to the paper feed by the separation roller 85, separating only the top original document from several other original documents. This operation is referred to as the paper feed / separation operation.

[0052] The original document MS, separated into individual sheets by the action of the paper feed belt 84 and the separation roller 85, enters the registration section C. The leading edge of the original document MS is detected as it passes directly beneath the abutment sensor 72. The paper feed belt 84 then continues its endless movement for a predetermined time from the moment the leading edge of the original document MS is detected by the abutment sensor 72. As a result, the leading edge of the original document MS abuts against the contact point between the pull-out drive roller 86 and the pull-out driven roller 87, which rotates while in contact with it.

[0053] The pull-out driven roller 87 is responsible for transporting the original document MS to the intermediate roller pair 66 on the downstream side in the transport direction, and is rotationally driven by the reverse rotation of the paper feed motor 76. When the paper feed motor 76 reverses, the pull-out driven roller 87 and one of the rollers in the intermediate roller pair 66 that are in contact with each other begin to rotate, and the endless movement of the paper feed belt 84 stops. At this time, the pickup roller 80 also stops rotating.

[0054] The document MS, fed out from the pull-out driven roller 87, passes directly beneath the document width sensor 73 (fourth detection unit). The document width sensor 73 is composed of multiple paper detection units, such as reflective photosensors, and these paper detection units are arranged in the width direction of the document MS (the direction perpendicular to the paper surface in Figure 5, and the direction perpendicular to the transport direction of the document MS). In other words, the document width sensor 73 is a sensor for detecting the width of the document MS. The ADF 51 calculates the size (width) of the document MS in the width direction based on which of the document width sensors 73 detects the document MS.

[0055] The document MS, whose width has been detected by the document width sensor 73, enters the turn section D and is caught between the contact points of the intermediate roller pair 66. The transport speed of the document MS by this intermediate roller pair 66 is set to be faster than the transport speed of the document MS in the first reading transport section E, which will be described later. This shortens the time it takes to feed the document MS to the first reading transport section E.

[0056] As the document MS is transported within the turn section D, its leading edge passes a position opposite the reading entrance sensor 67. When the leading edge of the document MS is detected by the reading entrance sensor 67, the transport speed by the intermediate roller pair 66 is reduced until the leading edge is transported to the position of the reading entrance roller pair 89, 90 on the downstream side in the transport direction. Furthermore, upon the start of rotational drive of the reading motor (not shown), one roller in the reading entrance roller pair 89, 90, one roller in the reading exit roller pair 92, and one roller in the second reading exit roller pair 93 each begin to rotate.

[0057] Within the turn section D, the original document MS is transported along a curved transport path between the intermediate roller pair 66 and the reading entrance roller pair 89 and 90, during which time its upper and lower surfaces are reversed and its transport direction is reversed. The leading edge of the original document MS, having passed through the nip between the reading entrance roller pair 89 and 90, then passes directly beneath the resist sensor 65. Hereafter, the operation up to this point after the paper feeding / separation operation will be referred to as the pull-out operation.

[0058] When the leading edge of the document MS is detected by the resist sensor 65, the transport speed is reduced while traveling a predetermined transport distance. Then, the rotational drive of the pull-out drive roller 86 and the intermediate roller pair 66 is stopped by the stop of the transport motor 97 (described later), and the rotational drive of the reading inlet roller pair 89 and 90 is stopped by the stop of the reading motor (not shown). As a result, the transport of the document MS is temporarily paused at the resist position in front of the first reading transport unit E. The controller 60 also transmits a resist stop signal to the reading control unit 150a of the scanner 150 (described later).

[0059] When the reading control unit 150a receives a registration stop signal from the controller 60, it transmits a reading start signal, which is a paper feed permission signal, to the controller 60. The controller 60 then restarts the rotation of the transport motor 97 and the reading motor. At the timing when the leading edge of the document MS, calculated based on the pulse count of the reading motor, reaches the reading position of the first fixed reading unit 151, the controller 60 transmits a gate signal to the reading control unit 150a indicating the effective image area in the sub-scanning direction of the first surface of the document MS. The controller 60 continues to transmit the gate signal until the trailing edge of the document MS leaves the reading position of the first fixed reading unit 151, and the first surface of the document MS is read by the first fixed reading unit 151.

[0060] After the document MS has passed through the first reading transport unit E, it passes through the reading exit roller pair 92, and its leading edge is detected by the paper discharge sensor 61. When single-sided reading mode is set, reading the second side of the document MS by the second fixed reading unit 95 is unnecessary. Therefore, when the leading edge of the document MS is detected by the paper discharge sensor 61, the driving force of the transport motor 97 is connected to the paper discharge roller pair 94 by the paper discharge clutch 99, which will be described later. Then, based on the paper discharge motor pulse count since the leading edge of the document MS was detected by the paper discharge sensor 61, the timing for the trailing edge of the document MS to exit the nip of the paper discharge roller pair 94 is calculated. Based on this calculation result, the operation of the paper discharge clutch 99 is stopped.

[0061] On the other hand, when the double-sided reading mode is set, the timing from when the leading edge of the document MS is detected by the paper ejection sensor 61 until it reaches the second fixed reading unit 95 is calculated based on the pulse count of the reading motor. At that timing, the controller 60 transmits a gate signal to the reading control unit 150a indicating the effective image area in the sub-scanning direction on the second side of the document MS. The controller 60 continues to transmit the gate signal until the trailing edge of the document MS leaves the reading position of the second fixed reading unit 95, and the second side of the document MS is read by the second fixed reading unit 95.

[0062] The second fixed reading unit 95 consists of a contact image sensor (CIS), and its reading surface is coated to prevent vertical streaks caused by adhesive foreign matter adhering to the document MS adhering to the reading surface. Opposite the second fixed reading unit 95, a second reading roller 96 is provided as a document support means to support the document MS from the non-reading side. This reading roller 96 prevents the document MS from lifting at the reading position by the second fixed reading unit 95 and also functions as a reference white area for acquiring shading data in the second fixed reading unit 95.

[0063] (Hardware configuration of image forming apparatus) Figure 9 shows an example of the hardware configuration of the image forming apparatus according to this embodiment. The hardware configuration of the image forming apparatus 100 according to this embodiment will be described with reference to Figure 9.

[0064] As shown in Figure 9, the ADF51 includes a controller 60, a document set sensor 56, a document length sensor 57, a rear end detection sensor 58, a paper discharge sensor 61, a registration sensor 65, a reading inlet sensor 67, a stop sensor 72, a document width sensor 73, a paper feed motor 76, a transport motor 97, a pull-out clutch 98, and a paper discharge clutch 99. As shown in Figure 9, the image forming unit 1 includes a main unit control unit 1a and a touch panel 157. As shown in Figure 9, the scanner 150 includes a reading control unit 150a. The main unit control unit 1a and the controller 60, the controller 60 and the reading control unit 150a, and the reading control unit 150a and the main unit control unit 1a are all connected to each other and can communicate with one another.

[0065] The controller 60 is a device that controls the operation of the paper feed motor 76, transport motor 97, pull-out clutch 98, and paper discharge clutch 99, etc., based on detection signals from each sensor. The controller 60 has a CPU (Central Processing Unit) 60a, a ROM (Read Only Memory) 60b, and a RAM (Random Access Memory) 60c.

[0066] The CPU 60a is an arithmetic unit that controls the operation of the ADF 51. The ROM 60b is a non-volatile memory device that stores the operation program of the ADF 51, etc. The RAM 60c is a volatile memory device used as the work area of ​​the CPU 60a.

[0067] Furthermore, the main control unit 1a and the read control unit 150a are equipped with a CPU, ROM, and RAM, similar to the controller 60.

[0068] The pull-out clutch 98 is a clutch component that connects and disconnects the rotational driving force of the transport motor 97 to the pull-out drive roller 86. The paper discharge clutch 99 is a clutch component that connects and disconnects the rotational driving force of the transport motor 97 to the paper discharge roller pair 94.

[0069] The main control unit 1a is a controller that controls the operation of the image forming unit 1.

[0070] The reading control unit 150a is a controller that controls the operation of the scanner 150.

[0071] (Configuration and operation of the functional blocks of the image forming apparatus) Figure 10 shows an example of a functional block of an image forming apparatus according to this embodiment. The configuration of the functional block of the image forming apparatus 100 according to this embodiment will be described with reference to Figure 10.

[0072] As shown in Figure 10, the ADF51 includes a paper feed control unit 201, a determination unit 202, and a notification unit 203.

[0073] The paper feed control unit 201 is a functional unit that controls various motors based on detection signals from the various sensors of the ADF 51 described above, and feeds and transports the document MS placed on the document tray 53 into the transport unit 54.

[0074] The determination unit 202 is a functional unit that determines the state of the document MS based on detection signals from various sensors in the ADF 51. For example, as shown in (Table 1) below, the determination unit 202 determines the state of the document MS placed on the document tray 53 according to the detection results of the document set sensor 56 and the rear end detection sensor 58 when the paper feeding operation of the document MS placed on the document tray 53 by the paper feed control unit 201 is started. Specifically, if the document set sensor 56 is in the off state and the rear end detection sensor 58 is also in the off state, the determination unit 202 determines that the document MS placed on the document tray 53 has been removed by the user. Also, if the document set sensor 56 is in the off state and the rear end detection sensor 58 is in the on state, the determination unit 202 determines that the document MS placed on the document tray 53 has moved backward to the upstream side and moved out of its normal placement position (hereinafter, this may be referred to as the "out of placement position" state). Displacement often occurs, for example, when the original document MS is a curled original. In addition, the determination unit 202 determines that the original document MS is placed on the original document tray 53 if the original document set sensor 56 is on, regardless of whether the rear end detection sensor 58 is on or off.

[0075] [Table 1]

[0076] The notification unit 203 is a functional unit that, when the determination unit 202 determines that the original document MS has been pulled out or has moved out of its placement position, and the paper feed control unit 201 stops the paper feeding operation of the original document MS, notifies the image forming unit 1 of the reason for the stop (i.e., the determination result by the determination unit 202).

[0077] The paper feed control unit 201, determination unit 202, and notification unit 203 described above are implemented by the execution of a program by the CPU 60a shown in Figure 9. Note that some or all of the paper feed control unit 201, determination unit 202, and notification unit 203 may be implemented not by a software program, but by hardware circuits such as an FPGA (Field-Programmable Gate Array) or ASIC (Application Specific Integrated Circuit).

[0078] Note that the paper feed control unit 201, determination unit 202, and notification unit 203 of the ADF51 shown in Figure 10 are conceptual representations of their functions and are not limited to this configuration. For example, the multiple functional units shown as independent functional units in the ADF51 in Figure 10 may be configured as a single functional unit. Alternatively, the functions of one functional unit in the ADF51 shown in Figure 10 may be divided into multiple functions and configured as multiple functional units. Furthermore, each functional unit of the ADF51 does not need to be configured as a clear software module as a block as shown in Figure 10; the individual functions of each functional unit may be realized as a whole when a program is executed in the ADF51.

[0079] As shown in Figure 10, the image forming unit 1 has a display control unit 301.

[0080] The display control unit 301 is a functional unit that controls the display operation of the touch panel 157. The display control unit 301 is realized by the execution of a program by the CPU provided in the main unit control unit 1a.

[0081] (Continuous paper feeding operation of the ADF) Figure 11 shows an example of the arrangement of the rear end detection sensor and sensors for detecting the size of the document in the ADF according to this embodiment. The continuous paper feeding operation of the document MS by the ADF 51 according to this embodiment will be described with reference to Figure 11.

[0082] As shown in Figure 11, when a user places a document MS on the document tray 53 and the document set sensor 56 detects that the document MS has been placed, the paper feed control unit 201 calculates the length of the document MS placed on the document tray 53 based on the detection signals from multiple document length sensors 57 (three document length sensors 57 in the example shown in Figure 11) and waits until a paper feed start request is received. When the paper feed control unit 201 receives a paper feed start request from the main unit control unit 1a, it starts the paper feed operation. The paper feed control unit 201 then feeds the document MS into the transport unit 54 and calculates the width of the document MS based on the detection signals from multiple document width sensors 73 (four document width sensors 73 in the example shown in Figure 11) located downstream of the document set sensor 56 (inside the transport unit 54), and calculates the size of the document MS based on the document length and the document width. Subsequently, the paper feed control unit 201 transports a predetermined amount of the document MS according to the calculated size of the document MS. When a predetermined amount of the original document MS is transported, the rear end of the original document MS passes the rear end detection sensor 58, and if the original document MS is the last sheet, the rear end detection sensor 58 is turned off. In other words, the determination unit 202 determines whether there is a next document for the original document MS based on the detection signal from the rear end detection sensor 58 when the original document MS has been transported by the predetermined amount. If the rear end detection sensor 58 is turned on when the original document MS has been transported by the predetermined amount, the determination unit 202 determines that there is a next document for the original document MS and outputs a paper feed operation request to feed the next document. When the paper feed control unit 201 receives a paper feed operation request from the determination unit 202, it starts feeding the original document MS (the next document). If a paper feed start request is received from the main unit control unit 1a, the determination unit 202 will also output a paper feed operation request for the first document in the bundle of original document MS. On the other hand, if the rear end detection sensor 58 is in the off state when a predetermined amount of the original document MS has been transported, the determination unit 202 determines that there is no further document for the original document MS, and does not output a paper feed operation request, and the paper feed control unit 201 does not start the paper feed operation.

[0083] The above predetermined amount represents the amount transported from the time the size of the original document MS is calculated. However, it can also be interpreted as the amount transported from the placement position detected by the original document set sensor 56, and in this case, the predetermined amount will also be an amount corresponding to the size of the original document MS.

[0084] (Regarding conventional document feeding operations) Figure 12 is a flowchart showing the flow of a conventional document feeding operation. After the document feeding operation for a document has started, if the user pulls out the document or the document moves out of its position, the main unit control is notified by the ADF controller that there is another document, and therefore the job needs to be stopped due to a jam. Now, referring to Figure 12, the conventional document feeding operation of an ADF will be explained.

[0085] The ADF internally determines whether a paper feed operation request exists (step S101). If a paper feed operation request occurs (step S101: Yes), it starts the paper feed operation (step S102). The timing of this paper feed operation request is the same as the timing described in Figure 11 above. When the paper feed operation starts, the ADF monitors the state of the document set sensor (step S103). If the document set sensor is in the off state (step S103: No), it determines that the document has been pulled out or moved out of position, and determines that an initial jam has occurred. At this time, the ADF immediately stops the paper feed operation and also stops the transport operation of the preceding paper (step S105). On the other hand, if the document set sensor is in the on state (step S103: Yes), the ADF continues the paper feed operation and continues transporting the document (step S104).

[0086] However, some users may pull out the placed document. If the paper feeding operation (including the transport of the preceding paper) is stopped in such a situation, it will be necessary to restart the process from transporting the preceding paper after the jam is cleared, and furthermore, the user will not be informed that the paper feeding operation stopped due to the removal of the document. Similarly, if the paper feeding operation (including the transport of the preceding paper) is stopped when the document is misplaced, the paper feeding operation will stop due to a jam, but the user will not be prompted to reposition the document.

[0087] Therefore, in this embodiment, as shown in Figure 13 which will be described later, we will explain an operation that improves user convenience by distinguishing between the withdrawal of a document and the displacement of a document from its placement position, and also completes the paper feeding operation for preceding papers that are already being fed.

[0088] (Flow of document feeding operation of the ADF according to this embodiment) Figure 13 is a flowchart showing an example of the document feeding operation of the ADF according to this embodiment. The document feeding operation of the ADF 51 according to this embodiment will be explained with reference to Figure 13.

[0089] <Step S11> The paper feed control unit 201 of the ADF51 determines whether or not a paper feed operation request has been output by the determination unit 202. The timing of when the determination unit 202 outputs a paper feed operation request is as described in Figure 11 above. If a paper feed operation request is output (step S11: Yes), the process proceeds to step S12.

[0090] <Step S12> The paper feed control unit 201 starts the paper feeding operation of the document MS placed on the document tray 53. Then, it proceeds to step S13.

[0091] <Step S13> The determination unit 202 makes a determination regarding the detection signal of the document set sensor 56 when the paper feed control unit 201 starts feeding the document MS. If the document set sensor 56 is ON (i.e., there is a document MS) (step S13: Yes), the process proceeds to step S14. If the document set sensor 56 is OFF (i.e., there is no document MS) (step S13: No), the process proceeds to step S15.

[0092] <Step S14> The paper feed control unit 201 continues the paper feeding operation of the original document MS placed on the original document tray 53.

[0093] <Step S15> Furthermore, the determination unit 202 makes a determination regarding the detection signal of the rear end detection sensor 58. If the rear end detection sensor 58 is ON (i.e., there is a document MS) (step S15: Yes), the process proceeds to step S16. If the rear end detection sensor 58 is OFF (i.e., there is no document MS) (step S15: No), the process proceeds to step S17.

[0094] <Step S16> In this case, the determination unit 202 determines that the original document MS has been misplaced. The process then proceeds to step S18.

[0095] <Step S17> In this case, the determination unit 202 determines that the original document MS has been removed from the document tray 53 by the user. Then, the process proceeds to step S18.

[0096] <Step S18> The paper feed control unit 201 completes the paper feeding operation of the preceding paper that was transported before the original document MS which is determined to have come off its placement position or been pulled out. If the feeding of the preceding paper is complete (step S18: Yes), the process proceeds to step S19. The process also proceeds to step S19 if there is no preceding paper.

[0097] <Step S19> The paper feed control unit 201 then stops all paper feeding operations of the original document MS. The process then proceeds to step S20.

[0098] <Step S20> If the ADF51's notification unit 203 determines that the document MS has been pulled out or moved out of its position, and the paper feed control unit 201 stops the paper feeding operation of the document MS, it notifies the display control unit 301 of the reason for the stop (i.e., the determination result by the determination unit 202). The display control unit 301 then displays the notification content from the notification unit 203 (the reason for stopping the paper feeding operation) on the touch panel 157.

[0099] The operations in steps S11 to S20 described above are repeated until all of the bundle of original documents MS are fed from the document tray 53, or until the paper feeding operation is stopped in step S19.

[0100] As described above, in the ADF 51 of the image forming apparatus 100 according to this embodiment, the document set sensor 56 detects when a document MS is placed on the placement position of the document placement table 53, the rear end detection sensor 58 is positioned upstream of the document set sensor 56 in the transport direction of the document MS and detects the passage of the rear end of the document MS when the document MS is transported from the document placement table 53, the paper feed control unit 201 controls the paper feeding operation of the document MS placed on the document placement table 53, and the determination unit 202 determines whether the document MS has been pulled out, whether the document MS has moved away from the placement position, or whether the document MS is properly placed in the placement position, based on the detection results of the document set sensor 56 and the rear end detection sensor 58 when the paper feeding operation of the document MS is started by the paper feed control unit 201. Specifically, when the paper feeding operation of the document MS is started by the paper feed control unit 201, the determination unit 202 determines that the document MS has been removed if the document MS is not detected by the document set sensor 56 and is not detected by the rear end detection sensor 58. If the document MS is not detected by the document set sensor 56 and is detected by the rear end detection sensor 58, the determination unit 202 determines that the document MS has moved away from its placement position. This allows the user to determine whether the document was removed from the placement tray or whether the document moved away from its placement position on the placement tray.

[0101] Furthermore, in the ADF 51 of the image forming apparatus 100 according to this embodiment, if the determination unit 202 determines that the original document MS has been withdrawn or has moved away from its placement position, the paper feed control unit 201 completes the transport operation of the preceding paper that was transported before the original document MS and stops the paper feed operation of the original document MS. This prevents the need for jamming if the preceding paper stops midway along the transport path, and also eliminates the need to place the preceding paper back in the placement position and perform the reading operation again.

[0102] In the above-described embodiment, if at least one of the functional units of the ADF 51 of the image forming apparatus 100 is implemented by program execution, the program is provided pre-installed in ROM or the like. Furthermore, in the above-described embodiment, the program executed by the ADF 51 of the image forming apparatus 100 may be provided as an installable or executable file recorded on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), flexible disk (FD), CD-R (Compact Disk-Recordable), or DVD (Digital Versatile Disc). Also, in the above-described embodiment, the program executed by the ADF 51 of the image forming apparatus 100 may be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. Finally, in the above-described embodiment, the program executed by the ADF 51 of the image forming apparatus 100 may be provided or distributed via a network such as the Internet. Furthermore, in the above-described embodiment, the program executed by the ADF 51 of the image forming apparatus 100 is configured as a module that includes at least one of the above-described functional units. In actual hardware, the CPU 60a reads the program from the above-described storage device (ROM 60b) and executes it, thereby loading and generating the above-described functional units onto the main memory (RAM 60c).

[0103] The embodiments of the present invention are as follows. <1> An automatic document transport device that automatically transports a document to the reading position of an image reader, A first detection unit detects that the document has been placed in the designated position on the document placement platform, A second detection unit is positioned upstream of the first detection unit in the document transport direction and detects the passage of the rear end of the document when the document is transported from the document placement table. A paper feed control unit that controls the paper feeding operation of the document placed on the document placement table, When the paper feeding operation of the document is started by the paper feeding control unit, a determination unit determines whether the document has been pulled out, whether the document has moved away from the previously placed position, or whether the document is properly placed in the previously placed position, according to the detection results of the first detection unit and the second detection unit. This is an automatic document transport device equipped with [a specific feature / feature]. <2> The determination unit, when the paper feeding operation of the document is started by the paper feeding control unit, If the first detection unit does not detect the document, and the second detection unit does not detect the document, it is determined that the document has been removed. If the first detection unit has not detected the document, and the second detection unit has detected the document, the unit determines that the document has moved away from the previously described placement position. <1> This is the automatic document transport device described in [reference]. <3> If the determination unit determines that the document has been pulled out or that the document has moved away from its previously placed position, the paper feed control unit stops the document feeding operation and completes the transport operation of the preceding paper that was transported before the document. <1> or <2> This is the automatic document transport device described in [reference]. <4> If the determination unit determines that the document has been pulled out or has moved away from the previously described placement position, and the paper feeding control unit stops the paper feeding operation, the notification unit further comprises a notification unit that notifies the reason for stopping the paper feeding operation. <3> This is the automatic document transport device described in [reference]. <5> The determination unit determines that if a predetermined amount of the original has been transported by the paper feed control unit and is detected by the second detection unit, there is a next original; if it is not detected by the second detection unit, it determines that there is no next original. When the determination unit determines that there is a next document, the paper feed control unit starts the paper feeding operation for the next document. <1> ~ <4> It is an automatic document transport device as described in any one of the items. <6> A third detection unit that detects the length of the document in the transport direction, A fourth detection unit that detects the width of the document in a direction perpendicular to the transport direction, Furthermore, The paper feed control unit calculates the size of the document based on the detection results of the third detection unit and the fourth detection unit, and transports the document in the predetermined amount according to the size. <5> This is the automatic document transport device described in [reference]. <7> The aforementioned <1> ~ <6> An image forming apparatus equipped with an automatic document transport device as described in any one of the items. <8> The aforementioned <4> The automatic document transport device described above, A display control unit that causes the content notified by the notification unit to be displayed on a display device, This is an image forming apparatus equipped with the following features. <9> A method for transporting an automatic document transport device that automatically transports a document to the reading position of an image reader, A first detection step in which the first detection unit detects that the document has been placed on the placement position of the document placement platform, A second detection step is provided, which is located upstream of the first detection unit in the document transport direction, and detects the passage of the trailing edge of the document when the document is transported from the document placement table, A paper feed control step that controls the paper feeding operation of the document placed on the document placement table, When the paper feeding operation of the document is started in the paper feeding control step, a determination step is performed to determine, according to the detection results of the first detection step and the second detection step, whether the document has been pulled out, whether the document has moved away from the previously placed position, or whether the document is properly placed in the previously placed position. This is a transport method that has [a certain feature]. [Explanation of Symbols]

[0104] 1 Image forming unit 1a Main Unit Control 2. Optical writing device 3, 3C, 3M, 3K, 3Y imaging unit 4, 4C, 4M, 4K, 4Y photoconductor 6, 6C, 6M, 6K, 6Y developing device 7 Stirring section 8 Conveyor screw 9 developing case 10 Toner density sensor 11. Developing Section 12 developing sleeves 13 Magnetic roller 14 Doctor Blade 15, 15C, 15M, 15K, 15Y Drum Cleaning Device 16 Cleaning Blades 17 Fur Brush 18 Electric field roller 19 Scraper 20 Recovery Screw 22 Static Elimination Lamp 23 Charging device 24 Transfer Units 25 Intermediate transfer belt 26, 26C, 26M, 26K, 26Y Primary Transfer Rollers 27 Lower tension roller 28 Paper transport unit 29 Paper conveyor belt 30 drive rollers 31 Secondary transfer roller 33 Resistola vs. 34 Fixing device 35 Paper output roller pair 36 Switchback device 37 Paper feed path 40-sheet feeding device 41 Paper Bank 42 Paper feed cassette 43 Sending roller 44 Feeding route 45 Separation Roller 46 Conveyor roller pair 50 Image Reading System 51 ADF 52 Main body cover 53 Manuscript Stand 54 Conveyor Unit 55. Document stacking stand 56 Document Set Sensor 56a Photointerrupter 56b Mechanical Flag 56c fulcrum 57 Document length sensor 58 Rear end detection sensor 60 Controllers 60a CPU 60b ROM 60c RAM 61 Paper output sensor 65 Resist Sensor 66 Intermediate Roller vs. 67 Read Inlet Sensor 72. Buttock sensor 73 Document width sensor 76 Paper feed motor 80 Pickup Roller 82 Drive rollers 83 Driven roller 84 Paper feed belt 85 Separation Roller 86 Pull-out drive roller 87 Pull-out driven roller 89 Read Inlet Roller Compatible 90 Read Inlet Roller Pair 92 Read-out exit roller pair 93 Second Read Exit Roller Compatible 94 Paper output roller pair 95 Second Fixed Reading Unit 96 Reading Roller 97 Conveyor motor 98 Pull-out clutch 99 Paper output clutch 100 Image forming apparatus 150 Scanners 150a Reading Control Unit 151 First Fixed Reading Unit 152 Mobile reading unit 153 Image reading sensor 154 First Contact Glass 155 Second Contact Glass 157 Touch panel 158 Start button 159 Hinge 201 Paper Feed Control Unit 202 Judgment section 203 Notification Department 301 Display Control Unit MS manuscript [Prior art documents] [License]

[0105] [License 1] Special Announcement No. 60-002539

Claims

1. An automatic document transport device that automatically transports a document to the reading position of an image reader, A first detection unit detects that the document has been placed in the designated position on the document placement platform, A second detection unit is positioned upstream of the first detection unit in the document transport direction and detects the passage of the trailing edge of the document when the document is transported from the document placement table. A paper feed control unit that controls the paper feeding operation of the document placed on the document placement table, When the paper feeding operation of the document is started by the paper feeding control unit, a determination unit determines whether the document has been pulled out, whether the document has moved away from the previously designated placement position, or whether the document is properly placed in the previously designated placement position, according to the detection results of the first detection unit and the second detection unit. An automatic document transport device equipped with the following features.

2. The determination unit, when the paper feeding operation of the document is started by the paper feeding control unit, If the first detection unit does not detect the document, and the second detection unit does not detect the document, it is determined that the document has been removed. The automatic document transport device according to claim 1, wherein if the document is not detected by the first detection unit and the document is detected by the second detection unit, it is determined that the document has moved away from the previously described placement position.

3. The automatic document transport device according to claim 1 or 2, wherein the paper feed control unit, when it is determined by the determination unit that the document has been pulled out or has moved away from the previously described placement position, completes the transport operation of the preceding paper that was transported before the document and stops the paper feed operation of the document.

4. The automatic document transport device according to claim 3, further comprising a notification unit that notifies the reason for stopping the paper feeding operation when the determination unit determines that the document has been pulled out or has moved away from the previously described placement position, and the paper feeding control unit stops the paper feeding operation.

5. The determination unit determines that if a predetermined amount of the original has been transported by the paper feed control unit and is detected by the second detection unit, there is a next original; if it is not detected by the second detection unit, it determines that there is no next original. The automatic document transport device according to claim 1 or 2, wherein the paper feed control unit determines that there is a next document, and the determination unit determines that there is a next document, and the paper feed control unit starts the paper feeding operation for the next document.

6. A third detection unit that detects the length of the document in the transport direction, A fourth detection unit that detects the width of the document in a direction perpendicular to the transport direction, Furthermore, The automatic document transport device according to claim 5, wherein the paper feed control unit calculates the size of the document based on the detection results of the third detection unit and the fourth detection unit, and transports the document by a predetermined amount according to the size.

7. An image forming apparatus comprising an automatic document transport device according to claim 1 or 2.

8. The automatic document transport device according to claim 4, A display control unit that causes the content notified by the notification unit to be displayed on a display device, An image forming apparatus equipped with [a specific feature].

9. A method for transporting an automatic document transport device that automatically transports a document to the reading position of an image reader, A first detection step in which the first detection unit detects that the document has been placed in the designated position on the document placement platform, A second detection step is provided, which is positioned upstream of the first detection unit in the document transport direction, and detects the passage of the trailing edge of the document when the document is transported from the document placement table, A paper feed control step that controls the paper feeding operation of the document placed on the document placement table, When the paper feeding operation of the document is started in the paper feeding control step, a determination step is performed to determine, according to the detection results of the first detection step and the second detection step, whether the document has been pulled out, whether the document has moved away from the previously described placement position, or whether the document is properly placed in the previously described placement position. A transport method having

Images