JP2010265044A - Automatic document feeder and image forming device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically feed even a small-sized document while suppressing cost of an automatic document feeder when prescribed conditions are met. <P>SOLUTION: CPU 300 of this image forming device 150 executes a program comprising steps of: displaying an input screen for setting a scan mode, thickness of the document, and image quality on a display panel (S1010) when the document is set in a document tray (YES in S1000); displaying a confirmation screen on the display panel (S1060) when the setting is input (YES in S1050); calculating a shorter jam threshold LTH based on the scan mode, thickness of the document, and image quality (S1090) when a start button is pressed down (YES in S1080); detecting the length L of the document in the conveyance direction (S1120); and continuing the processing (S1140) when L is greater than or equal to LTH (YES in S1130). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder that automatically feeds a document to an image forming apparatus or the like that forms an image on a recording medium (typically, recording paper) by an electrophotographic method or the like, and in particular, a short document such as a business card. The present invention relates to an automatic document feeder that can automatically convey a document as much as possible even if the length in the conveyance direction is a document shorter than a standard threshold value set based on the distance between the conveyance rollers. The present invention also relates to an image forming apparatus provided with such an automatic document feeder.

  2. Description of the Related Art Conventionally, an automatic document feeder that conveys a plurality of documents in order from the first page to a predetermined image reading position and discharges the document after the image reading is performed in the order of pages is a copying machine (copier), a facsimile machine, It may be provided in a scanner device or the like. In order to minimize the installation space of a copying machine or the like equipped with such an automatic document feeder, a compact automatic document feeder is required. In order to meet these demands, an automatic document feeder called a wingless type in which a document tray and a document discharge tray are arranged vertically has been proposed.

  When such an automatic document feeder is provided in an image forming apparatus such as a copying machine, the operation speed of feeding the document to the document reading unit by the automatic document feeder cannot follow the operation speed of continuous copying in the copying machine. The ability of the image forming apparatus cannot be fully demonstrated. Therefore, it is important to increase the document feeding operation speed by such an automatic document feeder.

  Note that document reading methods in an image forming apparatus provided with such an automatic document feeder may be broadly classified into two types. The automatic document feeder feeds the document onto the contact glass, scans the scanner section while the document is stationary, reads the document, and discharges the document when scanning is completed. This is a type in which a document is read by a scanner unit that is stationary while being conveyed (the scanner unit may be the same as or different from the scanner unit described above). In the former type, the document conveyance speed by the automatic document conveyance device is not related to the image quality (although the scanning speed of the scanner unit is related to the image quality), in the latter type, the document conveyance speed is related to the image quality. In the latter type, when high image quality is required, the document conveyance speed may not be increased. The present invention mainly relates to the latter type of automatic document feeder.

  Further, in such an automatic document feeder, the document is fed to the next pair of conveyance rollers by rotating the roller with the document sandwiched between the pair of conveyance rollers. Therefore, the length of the document in the conveyance direction that can be automatically conveyed is determined by the distance between the conveyance roller pair and the conveyance roller pair. If a large number of conveyance roller pairs are arranged and the distance between the conveyance roller pair and the conveyance roller pair is narrowed, even a document having a short length in the conveyance direction can be automatically conveyed, but the cost of the automatic document conveyance device increases. If the number of conveyance roller pairs is reduced in order to reduce the cost of the automatic document conveyance device, the distance between the conveyance roller pair and the conveyance roller pair becomes long, and a document having a short length in the conveyance direction cannot be automatically conveyed.

  In relation to such an automatic document feeder, there are known techniques described below. Japanese Laid-Open Patent Publication No. 2002-244361 (Patent Document 1) discloses an automatic document feeder that can quickly convey a document so that an image can be read efficiently. The automatic document feeder includes a document placing table on which a document is placed, a document feeding mechanism that sequentially feeds the document placed on the document placing table toward a predetermined image reading position at a predetermined interval, A document transport mechanism for unloading a document that has been read from the image reading position, a reversing mechanism for reversing the front and back of the document unloaded by the document transport mechanism, a document discharge table for stacking and storing the document on which the image has been read, and reversing And a discharge mechanism for discharging the document reversed by the mechanism to a document discharge table. In this automatic document feeder, the document conveyance distance between the document feeding mechanism and the image reading position is L1, the document conveyance distance between the image reading position and the reversing mechanism is L2, and the document length in the conveyance direction is Lp. In this case, a relationship of L2> L1 + 2 × Lp is established. In particular, the automatic document feeder is suitable for conveying a small-size document having a document length that is half or less of the maximum size that can be conveyed.

  In this automatic document feeder, in order to prevent the page order of the document from being reversed when the document after image reading is discharged onto the discharge tray and stacked, the front and back of the document after image reading has been performed even times. The document is discharged after being reversed (switched back only an odd number of times). In this case, the document conveyance interval can be shortened by arranging the relationship L2> L1 + 2 × Lp among the document conveyance distance L1, the document conveyance distance L2, and the document length Lp. Therefore, it is possible to quickly convey the document so that the image can be read efficiently without increasing the document conveyance speed. In particular, when transporting a small-size document having a document length that is half or less of the maximum transportable size, the size in the width direction of the automatic document feeder is made as small as possible by arranging such a relationship. However, the original can be conveyed so that the image can be read quickly.

  Japanese Patent Laid-Open No. 2001-139169 (Patent Document 2) discloses an automatic document feeder that can prevent a reduction in conveyance accuracy when a document is a small size, and can avoid unnecessary high-speed conveyance and reduce noise. To do. The automatic document feeder detects a document stacked on a document placement mechanism, separates the sheets one by one and feeds them to an image reading unit, and images a document fed from the sheet feeding unit. These are controlled by driving the paper discharge section that stops the reading section and re-transports and discharges the image after reading, and the conveyance paper discharge section and paper feed section, and sets two or more document conveyance speeds with different speeds. And a control unit capable of arbitrarily switching between. The control unit detects the document size based on a detection signal sent from the sheet feeding unit, and continuously feeds the document at a slower conveyance speed when the detected document size is a specific size. To do.

  According to the automatic document feeder, the control unit detects the document size based on the detection signal sent from the sheet feeding unit, and the detected document size is a specific size (when it is equal to or smaller than a predetermined size). In this case, the slower transport speed is set for a specific size that is likely to cause skew during separation and transport. Accuracy can be improved. That is, this automatic document feeder suppresses the occurrence of skew and the like by slowing the conveyance speed when the document size is equal to or smaller than a predetermined size.

  Furthermore, Japanese Patent Laid-Open No. 11-84756 (Patent Document 3) discloses an automatic document feeder that can prevent a decrease in processing speed even in the case of a small-size document. The automatic document feeder includes a document placing mechanism for placing a document, a document feeding mechanism for feeding a document set on the document placing mechanism, and a document fed by the document feeding mechanism. A document carry-in path guided upward, a registration roller pair for temporarily stopping the document transported by the document feeding mechanism disposed in the document carry-in path and transporting the stopped document toward the transparent plate, and a pair of registration rollers A document transport mechanism that transports the document transported to the document exposure position on the transparent plate, a document reversing mechanism that reverses the front and back of the document transported on the transparent plate and transports the document to the transparent plate through the document transport path, and transparent A document discharge mechanism for discharging a document for which exposure processing has been completed at a document exposure position on the plate, a document feeding mechanism, a pair of registration rollers, a document transport mechanism, a document reversing mechanism, and a control unit for controlling the document discharge mechanism; Comprising a document size detection mechanism for detecting the size of the document conveyed from the location mechanism to document exposure position on the transparent plate. This control unit discharges a document that has been exposed at the document exposure position on the transparent plate, and at the time of document replacement that transports the document conveyed to the pair of registration rollers toward the transparent plate, Based on the detection signal, when the original is larger than the predetermined value, the original conveying mechanism and the registration roller pair are operated at the first conveying speed, and when the original is equal to or smaller than the predetermined value, the original conveying mechanism is faster than the first conveying speed. The document transport mechanism and the registration roller pair are operated at the first transport speed after transporting a predetermined amount of the document that is operated at the second transport speed and has been subjected to the exposure process.

  This automatic document conveying device discharges a document whose exposure processing has been completed at a document exposure position on a transparent plate, and at the time of exchanging a document for conveying a document conveyed to a pair of registration rollers toward the transparent plate, a document size detection mechanism The conveyance speed is changed based on the detection signal from. When the document is larger than the predetermined value, the document transport mechanism and the pair of registration rollers are operated at the first transport speed. When the document is less than the predetermined value, the document transport mechanism is operated at the second transport speed that is faster than the first transport speed. After a predetermined amount of the original that has been operated and the exposure process has been conveyed, the original conveyance mechanism and the registration roller pair are operated at the first conveyance speed. Therefore, even if the next original conveyed on the transparent plate is reversely fed, it is not returned and can be reliably discharged. Moreover, the second transport speed of the document before being fed forward by a predetermined amount from the transparent plate is set faster than the first transport speed for transporting the next document that has been primarily fed toward the transparent plate. , It is possible to prevent a decrease in processing speed.

JP 2002-244361 A JP 2001-139169 A Japanese Patent Laid-Open No. 11-84756

  The above-described known techniques are all provided in an image forming apparatus, relate to an apparatus that automatically conveys a document to a document reading unit, and relate to handling a small-size document. As described above, a document having a short length in the conveyance direction is not suitable for automatic conveyance. Basically, the size of a document that can be automatically conveyed is determined in consideration of the safety factor in the maximum value of the distance between the conveyance roller pair. The above-described known technology discloses an automatic document conveying device that suitably conveys a small-size document determined to be automatically conveyed in this way.

  In this way, it is also important to suitably convey a small-size document that has been determined to be automatically conveyed in advance. However, the length in the conveyance direction should be reduced without increasing the number of conveyance roller pairs (without increasing costs). It is also important to be able to automatically convey even a short document as much as possible.

  However, the above-described known technology is not an automatic document feeder developed from such a viewpoint. That is, even if the document is a small-size document that can be transported when specific conditions are met, it is impossible to transport the document uniformly. Therefore, the range of document sizes that can be automatically transported may be narrowed. .

  Therefore, according to the present invention, the size of a document that can be automatically conveyed is determined by determining that automatic conveyance is possible even for a small-size document when specific conditions are met while suppressing the cost of the automatic document conveyance device. It is an object of the present invention to provide an automatic document feeder that can be expanded and an image forming apparatus including the automatic document feeder.

  An automatic document feeder according to an aspect of the present invention is an automatic document feeder that conveys a document to an image reading unit. This automatic document transport device is configured to automatically set a document transport direction threshold value set based on a plurality of rollers provided along a document transport direction for transporting a document and a distance between the rollers. Storage means for storing the image, setting means for setting the conveyance conditions for the document to be conveyed, and based on the conveyance conditions, it is possible to automatically convey a document whose conveyance direction length is shorter than the conveyance direction threshold value And a control unit for controlling the roller for conveying the document based on the determined result.

  According to this automatic document conveying device, when the conveying condition for conveying the document satisfies a specific condition, the conveying direction length is shorter than the conveying direction threshold set based on the distance between the rollers. Even a small-sized document (such as a business card) can be determined to be automatically conveyed. Accordingly, it is possible to provide an automatic document feeder that can increase the size of a document that can be automatically conveyed while suppressing the cost of the automatic document feeder without increasing the number of rollers that convey the document.

  The automatic document feeder can be configured to further include detection means for detecting the length of the document in the conveyance direction during document conveyance. In this case, the determination means includes means for correcting the conveyance direction threshold value to the correction threshold value based on the conveyance condition, and if the detected conveyance direction length is longer than the corrected threshold value. And means for determining that the document can be automatically conveyed.

  According to this automatic document feeder, the length of the document in the conveyance direction is detected during conveyance of the document, and if the detected conveyance direction length is longer than the threshold value corrected based on the conveyance conditions, the document is It can be determined that automatic conveyance is possible.

  The setting means can be configured to include means for setting the conveyance conditions based on information input from the user.

  Of the transport conditions, the transport speed often affects the image quality. For this reason, for example, it becomes possible to automatically convey a small-size document by changing the conveyance speed based on the information about the image quality input by the user.

  The automatic document feeder can be configured to further include a document detection means for detecting a document of a specific size whose transport direction length is shorter than the transport direction threshold before transport. In this case, the determination unit can be configured to include a unit for correcting the conveyance direction threshold value to the correction threshold value based on the conveyance condition. The conveyance conditions can be set such that the corrected threshold value is shorter than the length in the conveyance direction of a document having a specific size.

  When a document of a specific size is detected, the transport condition is set so that the corrected threshold value is shorter than the length in the transport direction of the document of the specific size. In this way, the conveyance conditions are changed so that a document of a specific size can be automatically conveyed, and the document of a specific size can be automatically conveyed.

  The document detection means can be configured to include means for detecting a document of a specific size based on information input from the user.

  For example, when the user inputs to select a business card reading mode, it can be detected that a document of a specific size is a business card.

  The document detection means can be configured to include means for detecting a document of a specific size by detecting the size of the document placed on the document tray.

  For example, the size of the document can be detected by a sensor provided on the document tray, and it can be detected that the document of a specific size is a business card.

  The control means can be configured to include means for controlling to stop the document at a position where it can be easily taken out when the determination means determines that automatic conveyance is not possible.

  If it is determined that automatic conveyance cannot be performed during conveyance, the document is stopped at a position where it is easy to remove the document, so that the document can be easily removed. For this reason, the load of the return work which a user performs can be reduced.

  When the automatic document feeder includes a reversing conveyance path for reversing and conveying a document, the storage unit can automatically convey the sheet, which is set based on the distance between the rollers in the document conveyance path including the reversing conveyance path. It can be configured to include means for storing a threshold value in the direction of conveyance of a simple document.

  When reading the first surface (front surface) and the second surface (back surface) of the document, the automatic document transport device is provided with a reverse transport path. Even when such a reverse conveyance path is provided, the conveyance direction threshold value set based on the distance between the rollers in the conveyance reverse path is stored. For this reason, in the automatic document feeder provided with such a reverse conveyance path, the size of the document that can be automatically conveyed can be increased.

  The conveyance condition can be configured to be the thickness of the document. Further, the conveyance condition can be configured to be a document conveyance speed. It should be noted that the document conveyance speed can be configured to change depending on the required image quality.

  If the thickness of the document is small, it can be assumed that if the jam occurs, the document is seriously damaged and difficult to recover. Therefore, the size of the document that can be automatically conveyed is determined by using the thickness of the document as a conveyance condition. If the document conveyance speed is high, it can be assumed that the document can be conveyed by inertia even if the distance between the rollers is long. Therefore, the size of the document that can be automatically conveyed is determined by using the document conveyance speed as a conveyance condition. In this case, the conveyance speed varies depending on the image quality required by the user. The size of the document that can be automatically conveyed can be increased according to the thickness of the document and / or the document conveyance speed (required image quality).

  An image forming apparatus according to another aspect of the present invention includes any one of the automatic document feeders described above.

  According to this image forming apparatus, since the above-described automatic document conveyance device is provided, the conveyance direction threshold set based on the distance between the rollers is set when the conveyance conditions for conveying the document satisfy certain conditions. Even a small-sized document (such as a business card) whose conveyance direction length is shorter than the value can be determined to be automatically conveyed. Accordingly, it is possible to provide an image forming apparatus that can increase the size of a document that can be automatically conveyed while suppressing the cost of the automatic document conveyance device without increasing the number of rollers that convey the document.

  According to the present invention, it is possible to determine that automatic conveyance is possible even for a small-sized document (such as a business card) when specific conditions for document conveyance are met. Accordingly, an automatic document conveying device and an image including the automatic document conveying device that can increase the size of a document that can be automatically conveyed while suppressing the cost of the automatic document conveying device without increasing the number of rollers for conveying the document. A forming apparatus can be provided.

1 is a perspective view showing an appearance of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a simplified internal configuration of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a diagram illustrating a simplified internal configuration of an automatic document feeder in an image reading unit of the image forming apparatus illustrated in FIG. 1. FIG. 4 is a diagram for explaining an operation in a single-sided scan mode by the automatic document feeder shown in FIG. 3. FIG. 4 is a diagram for explaining an operation in a duplex scan mode by the automatic document feeder shown in FIG. 3. FIG. 4 is a diagram for explaining an operation of detecting the length of a document in the conveyance direction in the automatic document conveyance device shown in FIG. 3. FIG. 4 is a diagram for explaining a stop position of a short jam document in the automatic document feeder shown in FIG. 3. FIG. 4 is a diagram for explaining a distance between conveyance rollers in the automatic document conveyance device illustrated in FIG. 3. FIG. 2 is a functional block diagram illustrating a hardware configuration of the image forming apparatus illustrated in FIG. 1. It is a figure which shows the structure of the threshold value management table about the short jam memorize | stored with the image forming apparatus which concerns on the 1st Embodiment of this invention. 3 is a flowchart showing a control structure of an automatic document conveyance processing program executed by the image forming apparatus according to the first embodiment of the present invention. 6 is a flowchart illustrating a control structure of an automatic document conveyance processing program executed by an image forming apparatus according to a second embodiment of the present invention. 10 is a flowchart illustrating a control structure of an automatic document conveyance processing program executed by an image forming apparatus according to a third embodiment of the present invention.

  An automatic document feeder according to an embodiment of the present invention and an image forming apparatus including the automatic document feeder will be described. In the following description, the same parts are denoted by the same reference numerals. Their functions and names are also the same. Therefore, detailed description thereof will not be repeated. In the present embodiment, an electrophotographic image forming apparatus (multifunction machine) will be described. However, the present invention is not limited to this, and an automatic document feeder according to the embodiment of the present invention is provided. May be any of a copying machine, a facsimile machine, and a scanner.

-First embodiment-
[Image forming apparatus]
FIG. 1 is a diagram illustrating an external configuration of the image forming apparatus 150. FIG. 2 is a diagram illustrating a simplified internal configuration of the image forming apparatus 150. FIG. 3 is a diagram showing a simplified internal configuration of the automatic document feeder 153 in the image reading unit 152 of the image forming apparatus 150, and FIGS. 4 to 8 show a simplified document conveyance state in the automatic document feeder 153. FIG. FIG. 9 is a functional block diagram of the image forming apparatus 150.

  Referring to FIGS. 1 and 2, the image forming apparatus 150 includes a document reading unit 152, an image forming unit 154, a paper feeding unit 156, and a paper discharge processing device 158. The document reading unit 152 includes an automatic document feeder 153.

  Hereinafter, the internal configuration of the image forming apparatus 150 will be described by describing the operation in the copy mode.

  In the image forming apparatus 150, a document placed on a document placement table is read as image data by the document reading unit 152, and the read image data is a CPU (Central Processing Unit) composed of a microcomputer or the like shown in FIG. 300, various image processing is performed on the image data, and the image data is output to the image forming unit 154.

  When the document is read by the document reading unit 152, the user places the document on the document table and the document is read by the document reading unit 152 in a stationary state, or is automatically conveyed by the automatic document conveying device 153. In some cases, an original document is read by the document reading unit 152. The document reading unit 152 provided on the upper portion of the image forming apparatus 150 is provided with a document placing table 296 (see FIG. 3) made of transparent glass on which the document is placed. Automatic document conveyance is provided above the document placing table 296. A device 153 is attached. The automatic document feeder 153 according to the present embodiment automatically conveys the document to the position of the document reading window 294 (see FIG. 3) of the document reading unit 152. Details of the automatic document feeder 153 will be described later.

  As shown in FIG. 1, the automatic document feeder 153 (upper part of the image reading unit 152) is configured to be able to rotate obliquely upward, and by opening the upper part of the document placing table, the user manually holds the document. It can be placed on the document table.

  The image forming unit 154 prints an image of a document indicated by image data on a recording sheet. The image forming unit 154 includes a photosensitive drum 222, a charging device 224, a laser scan unit (hereinafter referred to as “LSU”) 226, and development. A device 228, a transfer device 230, a cleaning device 232, a fixing device 234, a static elimination device (not shown), and the like are provided.

  The image forming unit 154 is provided with a main transport path 236 and a reverse transport path 238, and the recording paper fed from the paper feed unit 156 is transported along the main transport path 236. The paper feeding unit 156 pulls out the recording paper stored in the paper cassette 240 or the recording paper placed on the manual feed tray 242 one by one and sends the recording paper to the main conveyance path 236 of the image forming unit 154.

  While the recording paper is being conveyed along the main conveyance path 236 of the image forming unit 154, the recording paper passes between the photosensitive drum 222 and the transfer device 230, and further passes through the fixing device 234 to be recorded. Printing on paper is performed.

  The photosensitive drum 222 rotates in one direction, and its surface is cleaned by the cleaning device 232 and the static eliminator and then uniformly charged by the charging device 224.

  The LSU 226 modulates a laser beam based on the image data to be printed, and repeatedly scans the surface of the photosensitive drum 222 in the main scanning direction with the laser beam to form an electrostatic latent image on the surface of the photosensitive drum 222. To do.

  The developing device 228 develops the electrostatic latent image by supplying toner to the surface of the photosensitive drum 222, and forms a toner image on the surface of the photosensitive drum 222.

  The transfer device 230 transfers the toner image on the surface of the photosensitive drum 222 onto a recording sheet that passes between the transfer device 230 and the photosensitive drum 222.

  The fixing device 234 includes a heating roller 248 for heating the recording paper and a pressure roller 250 for pressing the recording paper. The recording sheet is heated by the heating roller 248 and pressed by the pressure roller 250, whereby the toner image transferred onto the recording sheet is fixed on the recording sheet.

  A branching claw 244 is disposed at a connection position between the main conveyance path 236 and the reverse conveyance path 238. When printing is performed only on one side of the recording paper, the branching claw 244 is positioned, and the recording paper from the fixing device 234 is guided to the paper discharge tray 246 or the paper discharge processing device 158 by the branching claw 244.

  When printing is performed on both sides of the recording paper, the branching claw 244 is rotated in a predetermined direction, and the recording paper is guided toward the reverse conveyance path 238. The recording sheet passes through the reverse conveyance path 238, is reversed on the front and back, and is conveyed again to the main conveyance path 236. During the re-conveyance of the main conveyance path 236, printing on the back surface is performed and the recording paper is discharged. It is guided toward the paper tray 246 or the paper discharge processing device 158.

  The recording paper printed as described above is guided toward the paper discharge tray 246 or the paper discharge processing device 158 and discharged to the paper discharge tray 246, or on each paper discharge tray 168 of the paper discharge processing device 158. Discharged to either.

  The paper discharge processing device 158 performs processing for sorting and discharging a plurality of recording papers to each paper discharge tray 168, processing for punching each recording paper, and processing for stapling each recording paper. For example, when creating a plurality of printed materials, each recording sheet is sorted and discharged to each paper discharge tray 168 so that a part of the printed material is allocated to each paper discharge tray 168. In addition, a punching process or a stapling process is performed on each recording sheet on the discharge tray 168 to create a printed matter.

[Automatic document feeder]
<Configuration of automatic document feeder>
The automatic document feeder 153 in the image reading unit 152 will be described with reference to FIG.

  As shown in FIG. 3, the automatic document feeder 153 includes a document tray 252 on which a document (either one sheet or two or more document bundles) is placed (set), and a document. A document presence / absence sensor 254 for detecting whether or not there is a document on the tray 252, a paper feed roller 256 as a driving roller, and a document transport as a driving roller for separating the documents one by one from a bundle of two or more documents. A roller 258. The paper feed roller 256 is lowered to a position in contact with the original when the paper is fed, and rises and waits at a time other than during the paper feed.

  The automatic document feeder 153 further includes a document conveyance roller 260 (and a document conveyance roller 262 paired therewith) provided on the conveyance path 266 and a document for detecting a document sent from the document conveyance roller 260. A conveyance sensor 264.

  The automatic document feeder 153 is further fed from a document carrying roller 268 that is a driving roller (and a document carrying roller 270 that is a driven roller that is paired with the document feeding roller 268) and a document carrying roller 268 provided in the carrying path 282. A document conveyance sensor 272 for detecting the original document, a document conveyance roller 274 that is a driving roller for discharging the document from the position of the document reading window 294 (and a document conveyance roller 276 that is a driven roller that is paired with the roller), A document discharge tray 292 on which a document discharged from the automatic document feeder 153 is placed, and a discharge roller 278 (and a pair thereof) as a driving roller for discharging the document to the document discharge tray 292 A paper discharge roller 280) which is a driven roller.

  The automatic document feeder 153 further includes a reverse conveyance path 290 that reverses the original and conveys it to the position of the original reading window 294 in order to read the second side after the first side of the double-sided original is read.

  The automatic document feeder 153 further includes a reversing roller 284 that is a driving roller (and a reversing roller 286 that is a driven roller that is paired with the driving roller) provided in the reversing conveyance path 290 and a document that is fed from the reversing roller 284. And a document conveyance sensor 288 for detecting the above.

  As described above, the transport path 266 is from the document tray 252 to the front of the document transport roller 268, the transport path 282 is from the document transport roller 268 to the front of the paper discharge roller 278, and the reverse transport path 290 is the front of the reverse roller 284. To the front of the document conveying roller 268.

  With the above-described configuration, automatic document feeder 153 according to the present embodiment automatically conveys a document placed on document tray 252 to the position of document reading window 294 of document reading unit 152, and discharges the document. It is discharged to the tray 292. The document reading unit 152 is provided with a document placing table 296, and a document is placed on the document placing table 296 by the user. Further, the arrangement of the conveying rollers and the driving form (combination of the driving roller and the driven roller) in the automatic document conveying device 153 shown in FIG. 3 are merely examples, and the present invention is limited to such an automatic document conveying device 153. Is not to be done. In particular, the reverse conveyance path 290 may not be provided.

<Operation of automatic document feeder (when scanning on one side)>
FIGS. 4A to 4E are diagrams illustrating a conveyance state of the document 400 during single-sided reading. Schematically, the paper feed roller 256 descends with respect to the original 400 (or original bundle) placed on the original tray 252 and draws the originals 400 one by one from the original bundle to read the original at the reading position. The documents 400 are conveyed one by one toward the window 294. The paper feed roller 256 moves up after the document 400 is discharged to the document discharge tray 292.

  As shown in FIGS. 4A to 4E, at the time of single-sided reading, all the rollers rotate only in one direction in which the original 400 is fed to convey the original 400. In the following description, the rotation direction of the pair of rollers formed by the driving roller and the driven roller will be described using the rotation direction of the driving roller.

  As shown in FIG. 4A, when the document 400 (or document bundle) is placed on the document tray 252, the document presence / absence sensor 254 detects that the document 400 is on the document tray 252. In this state, when a start button provided on the operation panel 170 of the image forming apparatus 150 is pressed, the paper feed roller 256 is lowered and the paper feed roller 256 is rotated clockwise as shown in FIG. And the document conveying roller 258 rotates clockwise. As a result, the documents 400 are pulled from the document tray 252 to the conveyance path 266 one by one.

  As shown in FIG. 4C, the document conveying roller 260 rotates clockwise and the document conveying roller 268 rotates counterclockwise. As a result, the document 400 drawn into the transport path 266 is transported to the transport path 282 and reaches the position of the document reading window 294. When the document 400 is transported to the position of the document reading window 294 (from when the document transport sensor 272 detects the document 400 until it is not detected), the document 400 is transported at a constant speed. Thus, while the original 400 is being conveyed at a constant speed, the original 400 is read by the optical mechanism (scanner unit).

  As shown in FIG. 4D, the document conveying roller 274 rotates counterclockwise and the paper discharge roller 278 rotates clockwise. As a result, the document 400 on the conveyance path 282 is discharged to the document discharge tray 292 as shown in FIG. When the document 400 is discharged to the document discharge tray 292 in this way, the feed roller 256 is raised and its rotation is stopped, and the rotation of the other rollers that have been rotated is also stopped.

<Operation of automatic document feeder (dual-side scanning)>
5 (A) to 5 (D) are views showing a conveyance state of the document 400 at the time of double-side reading, and are inserted between FIG. 4 (D) and FIG. 4 (E). . In general, when one side of the original 400 is read, the original 400 is stopped at the switchback position, the paper discharge roller 278 is rotated in the reverse direction (rotated counterclockwise), and the original 400 is moved to the reverse conveyance path 290. Send it in. When the original 400 reaches the original conveying roller 268 immediately before the original reading window 294, the paper discharge roller 278 is temporarily stopped and then rotated again (rotated clockwise).

  As shown in FIG. 4C, the document conveying roller 260 rotates clockwise and the document conveying roller 268 rotates counterclockwise. As a result, the document 400 drawn into the transport path 266 is transported to the transport path 282 and reaches the position of the document reading window 294. At the position of the document reading window 294, the first surface of the document 400 is read by an optical mechanism (scanner unit).

  As shown in FIG. 4D, when the document transport roller 274 rotates counterclockwise and the discharge roller 278 rotates clockwise, the document 400 on the transport path 282 is just before being discharged to the document discharge tray 292. It is transported to the switchback position. When the paper discharge roller 278 that has rotated clockwise is stopped, the document 400 is stopped at the switchback position, as shown in FIG.

  As shown in FIG. 5B, the stopped paper discharge roller 278 rotates counterclockwise, and the original document 400 stopped in the middle of discharge is drawn into the reverse conveyance path 290 to the document discharge tray 292.

  As shown in FIG. 5C, the reverse roller 284 rotates in the clockwise direction and the document conveying roller 268 rotates in the counterclockwise direction. As a result, the document 400 drawn into the reverse conveyance path 290 is conveyed again to the conveyance path 282 and reaches the position of the document reading window 294. At the position of the document reading window 294, the second surface of the document 400 is read by an optical mechanism (scanner unit). Note that when the document 400 reaches the document transport roller 268 immediately before the document reading window 294, the paper discharge roller 278 is temporarily stopped.

  As shown in FIG. 5D, the document conveying roller 274 rotates counterclockwise, and the paper discharge roller 278 that has been temporarily stopped rotates clockwise. As a result, the document 400 on the conveyance path 282 is discharged to the document discharge tray 292 as shown in FIGS. 4D and 4E. When the document 400 is discharged to the document discharge tray 292 in this way, the feed roller 256 is raised and its rotation is stopped, and the rotation of the other rollers that have been rotated is also stopped.

<Detection of length in original transport direction>
The automatic document feeder 153 according to the present embodiment detects the length of the document 400 in the conveyance direction while the document 400 is being conveyed. With reference to FIG. 6, the detection of the length of the document 400 in the conveyance direction will be described.

  As shown in FIG. 6A, when the document conveyance sensor 272 detects the document 400, detection of the length in the conveyance direction of the document 400 is started, and as shown in FIG. 6B, the document conveyance sensor 272 When the document 400 is no longer detected, the detection of the length of the document 400 in the conveyance direction is terminated. That is, the length of the document 400 in the transport direction is measured while the document transport sensor 272 detects the document 400. The measurement of the length of the document 400 in the conveyance direction is performed, for example, according to the following procedure.

  A stepping motor is used as a motor for driving the document conveyance roller, and the number of steps of the stepping motor from when the document conveyance sensor 272 is turned on (detection of the document 400 is started) to when it is turned off (detection of the document 400 is ended). Based on this, the length of the document 400 in the conveyance direction is measured. For example, when using a stepping motor having a conveyance distance of 0.0422 mm per step, if 5000 steps are counted from when the document conveyance sensor 272 is turned on to when it is turned off, 5000 × 0.0422 = 211.0, and it can be detected that the length of the document 400 in the conveyance direction is 211.0 mm.

  Note that the period from when the document conveyance sensor 272 is turned on to when it is turned off is when the document 400 is being conveyed to the position of the document reading window 294, and thus the document 400 is conveyed at a constant speed. As described above, since the length of the document 400 in the transport direction is detected while the document 400 is transported at a constant speed, the length of the document 400 in the transport direction can be detected with high accuracy.

<Short jam stop>
In the automatic document feeder 153 according to the present embodiment, as described above, when the length of the document in the conveyance direction is detected and the length is shorter than a predetermined value (short jam threshold), the short jam is detected. And the automatic document feeding is stopped. The purpose of determining such a short jam is to stop a small-size document that cannot be automatically conveyed at an appropriate position to reduce damage to the document.

  As shown in FIG. 7A, when the document 400 is stopped on the conveyance path 282 (not the reverse conveyance path 290), the automatic document conveyance device 153 (the upper part of the image reading unit 152) is rotated obliquely upward. By opening the upper part of the document placing table 296 (opening the document cover), the stopped document 400 can be confirmed. By stopping the document 400 at such a position, the document 400 can be easily taken out. Since it can be easily taken out, it can be taken out without damaging the original 400.

  If the original 400 is conveyed to the reverse conveying path 290 without stopping the original 400 at the position shown in FIG. 7A, the original 400 is opened by opening the original cover as shown in FIG. 7B. It gets stuck in a position where it is difficult to take out. For this reason, the document 400 cannot be taken out easily and without being damaged. Further, if the document is stopped at the position shown in FIG. 7B, it can be assumed that the document itself is seriously damaged (particularly a thin document).

<Threshold for short jam>
In general, in an automatic document feeder, a short jam threshold is set based on the longest roller interval in the conveyance path. The longest roller interval in the automatic document feeder 153 according to the present embodiment is L (2) shown in FIG. The longest roller interval L (2) is the interval between the reversing roller 284 and the document conveying roller 268 in the reversing conveyance path 290, and is, for example, 110 mm. For this L (2) (= 110 mm), the threshold for short jam is set to 125 mm in view of the safety factor. In a general automatic document feeder, the document 400 that is less than 125 mm is stopped at a predetermined position.

  Also in the automatic document feeder 153 according to the present embodiment, the longest roller interval is L (2) shown in FIG. On the other hand, the longest roller interval L (2) has no relation in the case of a single-sided original, but in the prior art, a short jam threshold value of 125 mm that is uniformly set based on the longest roller interval L (2). Documents 400 that are less than (even single-sided documents) were not automatically conveyed.

  In automatic document feeder 153 according to the present embodiment, the longest roller interval in the conveyance path for conveying a single-sided document is L (1) shown in FIG. The roller interval L (1) is an interval between the document conveying roller 268 and the document conveying roller 274 in the conveying path 282, and is 80 mm, for example. For this L (1) (= 80 mm), the threshold for short jam in the single-sided scan mode is set to 95 mm in view of the safety factor. For this reason, an original with a length of 100 mm in the conveyance direction of the original 400 is lower than the conventional short jam threshold of 125 mm, but is higher than the short jam threshold of 95 mm in the single-sided scan mode in the present embodiment. It can be transported.

  As described above, in the automatic document feeder 153 according to the present embodiment, different threshold values are set in accordance with the types of scan modes (double-sided scan / single-sided scan), and conventionally, the threshold is uniformly short. Even a document 400 that is determined to be jammed and cannot be automatically conveyed can be automatically conveyed as much as possible.

  Further, in the automatic document feeder 153 according to the present embodiment, in addition to such a scan mode (double-sided scan / single-sided scan), the document weighing (thin paper / plain paper / thick paper) and the image quality (high quality / normal paper) It is characterized in that it can be automatically conveyed as much as possible by changing the threshold value of the short jam according to the combination of (image quality / low image quality) (these are described as conveyance conditions).

  Such features include the hardware configuration of the image forming apparatus 150 (particularly, the configuration of the automatic document feeder 153) and the image forming apparatus 150 (the image forming apparatus 150 includes the image reading unit 152, and the image reading unit 152 includes Including an automatic document feeder 153). Hereinafter, the hardware configuration (control block diagram) included in the image forming apparatus 150 or the image reading unit 152 for executing this control will be described, and then the software configuration (program) will be described. 9 illustrates the hardware configuration (control block diagram) of the image forming apparatus 150, but the control unit 310 controls the entire image forming apparatus 150 even if the image forming apparatus 150 controls the image. It may be a device that controls the reading unit 152 or a device that controls the automatic document feeder 153.

[Hardware block]
Referring to FIG. 9, an image forming apparatus 150 includes an operation device 166 capable of setting each function relating to image forming processing, a control unit 310 mainly including a CPU 300, an image reading unit (scanner unit) 152, The image processing unit 320, the image storage unit 330, the image forming unit 154, and the optical sensor unit 340 (for example, the document presence / absence sensor 254, the document transport sensor 264, the document transport sensor 272, and the document transport sensor 288 are optically linked to the document 400. These sensors correspond to the case of detecting the motor.), A motor driver 350 and a driver 352, a platen document scanning unit driving motor 360 connected to the driver 350, and a paper feed roller connected to the driver 352. A vertical movement moving motor 362 and a document conveying roller driving motor 364 are included.

  The document transport roller drive motor 364 rotates not only the drive roller of the document transport roller but also the drive roller of the paper feed roller, the paper discharge roller, and the reverse roller. As described above, for example, a stepping motor is used as the document transport roller drive motor 364.

  In addition to the CPU 300, the control unit 310 is an input / output interface, for example, an HDD (Hard Disk Drive) 302 that is a nonvolatile storage device that can store programs and data even when power is cut off. An I / O (Input / Output) 304, a ROM (Read Only Memory) 306 for storing a program and the like, and a RAM (Random Access Memory) 308 for providing a storage area when executing the program are further provided. Including.

  In the control unit 310, the CPU 300, HDD 302, I / O 304, ROM 306, and RAM 308 are connected by a bus (not shown), and the CPU 300 executes a predetermined program to realize a general function as an image forming apparatus.

  The ROM 306 stores programs, data, and the like necessary for controlling the operation of the image forming apparatus 150. The CPU 300 controls the image forming apparatus 150 according to the program and data stored in the ROM 306 and executes control related to each function of the image forming apparatus 150.

  The RAM 308 provides a function as a working memory that temporarily stores the results of calculation and processing by the CPU 300 and a function as a frame memory that stores image data.

  The CPU 300 controls the document reading unit 152, the image forming unit 154, the plate-like operation panel 170 and the display panel 172 of the operation device 166, and the ROM 306, HDD 302, and RAM 308 by executing predetermined programs.

  The operation device 166 includes a plate-like operation panel 170 provided with a hardware button, which is a numeric keypad and other various operation buttons, disposed in a region on the right side of the surface of the operation device 166, and the operation device 166. And a display panel 172 configured from a small touch panel integrated liquid crystal display device disposed in the left region from the center. The operation panel 170 and the display panel 172 are held in one housing, and the operation device 166 is configured to be integrated as a whole.

  In the operation device 166, the display panel 172 displays the state of the image forming apparatus 150, the job processing status (for example, displaying a short jam error that occurred during processing), replacement of consumable parts, and a request for maintenance work. Is done. A selection button is displayed on the display area of the liquid crystal display device of the display panel 172. When the area where the selection button is displayed is pressed with a finger, the touch panel detects the pressed position. By comparing the display position of the selection button with the position where the touch panel is pressed on the program, the function setting, operation instruction, and the like of the image forming apparatus 150 are performed.

  As shown in FIG. 9, the image processing unit 320 and the external device are connected by an image data bus 370, and the control unit 310 and the external device are connected by a communication line. Further, the control block diagram shown in FIG. 9 is an example, and the present invention is not limited to such a control block diagram.

[Threshold management table]
FIG. 10 illustrates a threshold management table for short jams stored in a nonvolatile storage device such as the HDD 302 or the ROM 306. As described above, in the automatic document feeder 153 provided in the image forming apparatus 150 according to the present embodiment, the longest roller interval in the duplex scanning mode is L (2) (= 110 mm) shown in FIG. ) And the threshold of short jam in the double-sided scan mode is set to 125 mm for this L (2) (= 110 mm). The longest roller interval in the single-sided scan mode is shown in FIG. L (1) (= 80 mm) shown, and for this L (1) (= 80 mm), the threshold value of the short jam in the single-sided scan mode is set to 95 mm. This setting is a premise in the threshold management table shown in FIG.

  As shown in FIG. 10A, 95.0 mm is stored in the single-sided scan mode and 125.0 mm is stored in the double-sided scan mode as the standard threshold for short jams. This is stored based on the premise described above. For this reason, if the automatic document feeder is different, the standard threshold value is different because the arrangement of the rollers is different and the distance between the rollers is different.

  As shown in FIG. 10B, a coefficient (correction coefficient) with respect to the standard threshold value of the short jam is stored in correspondence with the document weighing (weight per unit area of the document 400). The coefficient 1.000 is stored when the original 400 is thin, the coefficient 0.980 is stored when the original 400 is plain paper, and the coefficient 0.950 is stored when the original 400 is thick paper.

  This coefficient is multiplied by the standard threshold value in FIG. 10A or the threshold value already multiplied by the coefficient. Since the coefficient increases as the document 400 is thinner, the threshold calculated by multiplying the standard threshold value increases as the document 400 is thinner. This means that the thinner the original 400 is, the higher the threshold value is corrected. When the original 400 is short, it is automatically conveyed if the original 400 is thick, but not automatically if the original 400 is thin. This is because if the thickness of the document 400 is thin, the document 400 itself is greatly damaged when a jam occurs, and / or it is difficult to recover from the jam. Other reasons may be used.

  As shown in FIG. 10C, a coefficient (correction coefficient) with respect to the standard threshold value of the short jam is stored in correspondence with the scanning speed (conveyance speed) of the document 400. Note that there is a relationship between the transport speed and the image quality that the higher the image quality, the lower the speed, and the lower the image quality, the faster. That is, when the user requests high image quality, the conveyance speed of the document 400 is set to a low speed, and when the user allows low image quality, the conveyance speed of the document 400 is set to a high speed. When the scan speed of the document 400 is low (high image quality), the coefficient 1.000, and when the scan speed of the document 400 is medium speed (normal image quality), the coefficient 0.980 is high, and the scan speed of the document 400 is high. In the case of (low image quality), a coefficient of 0.950 is stored.

  This coefficient is multiplied by the standard threshold value in FIG. 10A or the threshold value already multiplied by the coefficient. Since the coefficient decreases as the scanning speed of the document 400 increases, the threshold calculated by multiplying the standard threshold value decreases as the document 400 is scanned at a higher speed (lower image quality required by the user). . This means that the threshold is corrected to be lower as the conveyance speed of the original 400 is higher, and automatic conveyance is performed if the conveyance speed is high even if the original 400 is short. This is because when the conveyance speed of the original 400 is high, the conveyance between the conveyance roller pair and the conveyance roller pair can be carried by inertia. Other reasons may be used.

  As shown in FIG. 10D, the threshold value of short jam (corrected) is corrected by multiplying the standard threshold value by the coefficient associated with the document weighing and the coefficient associated with the scanning speed. Threshold) is stored.

  Conventionally, a document 400 (even a single-sided document) that is less than the short jam threshold 125 mm that is uniformly set based on the longest roller interval L (2) has not been automatically conveyed. In the automatic document feeder 153 according to the present embodiment (even if the conveyance roller pair is the same), even an original having a length in the conveyance direction of 85.7 mm can be automatically conveyed.

  In the image forming apparatus 150 provided with the automatic document feeder 153 according to the present embodiment, the document 400 that satisfies the user's requirements for image quality and the like as much as possible can be automatically performed even if the document 400 has a short length in the conveyance direction. Change the transport conditions so that it can be transported. Hereinafter, a control structure of a program for changing such a conveyance condition and automatically conveying the original 400 as much as possible will be described.

Software configuration
FIG. 11 is a flowchart showing a control structure of an automatic document conveyance processing program executed by CPU 300 (hereinafter simply referred to as CPU 300) of image forming apparatus 150 (or document reading unit 152, automatic document conveyance device 153). .

  Referring to FIG. 11, in step (hereinafter, step is referred to as S) 1000, CPU 300 determines whether or not document 400 is set on document tray 252 of automatic document feeder 153. At this time, when the document presence / absence sensor 254 detects the document 400, the CPU 300 determines that the document 400 is set on the document tray 252. If it is determined that document 400 is set on document tray 252 (YES in S1000), the process proceeds to S1010. If not (NO in S1000), the process returns to S1000 and waits until the document 400 is set on the document tray 252.

  In S1010, CPU 300 causes display panel 172 to display an input screen for scan mode (single side / double side), document thickness (thin paper / plain paper / thick paper), and image quality (high image quality / normal image quality / low image quality).

  In S1020, CPU 300 determines whether or not there is an input for setting a transport condition for the scan mode, document thickness, and image quality. At this time, the CPU 300 displays either a single-sided key or a double-sided key, which is a transport condition selection key corresponding to the scan mode, displayed on the display panel 172, or a thin paper key, which is a transport condition selection key corresponding to the thickness of the document. When any one of the plain paper key and the thick paper key, or any one of the high image quality key, the normal image quality key, and the low image quality key, which is a selection key for the transport condition corresponding to the image quality, is pressed, it is determined that the setting has been input. If it is determined that a setting input has been made (YES in S1020), the process proceeds to S1030. If not (NO in S1020), the process proceeds to S1040. It should be noted that YES is determined in the process of S1020 because one of the single-sided key and double-sided key is pressed and one of the thin paper key, plain paper key, and thick paper key is pressed, and the high-quality key, normal Although it is assumed that either the image quality key or the low image quality key is pressed, YES may be determined in the process of S1020 when at least one key is pressed. In this case, the transport condition in which the key is not pressed may be set as a default, or may be set so that the correction threshold value becomes higher (or lower). Absent.

  In S1030, CPU 300 displays a confirmation screen on display panel 172. At this time, settings (or default settings, etc.) input by the user regarding the scan mode, the thickness of the document, and the image quality are displayed. Thereafter, the process proceeds to S1050.

  In S1040, CPU 300 determines whether or not a predetermined time has elapsed after the input screen is displayed on display panel 172 and a timeout has occurred. If time-out occurs (YES in S1040), this process ends. Until the time-out occurs (NO in S1040), the process returns to S1010 to display the input screen on the display panel 172 and wait until the setting of the conveyance condition is input by the user.

  In S1050, CPU 300 determines whether or not there is an input for confirming the transport conditions input for the scan mode, the thickness of the document, and the image quality. At this time, the CPU 300 displays on the display panel 172 the settings input for the scan mode, the settings input for the thickness of the document, and the settings input for the image quality, and the “OK” key and the “reset” key. When it is displayed and the “OK” key is pressed, it is determined that a confirmation input has been made. If it is determined that a confirmation input has been made (YES in S1050), the process proceeds to S1060. If not (NO in S1050), the process proceeds to S1070.

  In S1060, CPU 300 displays a copy-capable screen on display panel 172. Thereafter, the process proceeds to S1080.

  In S1070, CPU 300 determines whether or not a predetermined time has elapsed after the confirmation screen is displayed on display panel 172 and a timeout has occurred. If time-out occurs (YES in S1070), this process ends. Until the time-out is reached (NO in S1070), the process returns to S1030, a confirmation screen is displayed on the display panel 172, and the process waits until confirmation of setting of the conveyance conditions is input by the user.

  In S1080, CPU 300 determines whether or not a start button provided as a hardware button on operation device 166 has been pressed. If it is determined that the start button has been pressed (YES in S1080), the process proceeds to S1090. If not (NO in S1080), the process proceeds to S1100.

  In S1090, CPU 300 calculates short jam threshold value (correction threshold value) LTH. At this time, the scan mode (single-sided / double-sided), document thickness (thin paper / plain paper / thick paper), image quality (high quality = low speed / normal quality = medium speed / low quality = high speed) input and confirmed by the user The threshold value LTH of the short jam is calculated based on the transport conditions relating to the threshold value and the threshold value management table shown in FIG. Thereafter, the process proceeds to S1110.

  In S1100, CPU 300 determines whether or not a predetermined time has elapsed since the display of the copyable screen on display panel 172, resulting in a timeout. If time-out occurs (YES in S1100), this process ends. Until time-out occurs (NO in S1100), the process returns to S1060 to display a copy-capable screen on the display panel 172 and wait until the start button is pressed.

  In step S1110, the CPU 300 lowers the paper feed roller 256 to rotate it counterclockwise, and rotates the other conveyance rollers in the direction in which the document 400 is fed.

  In S1120, CPU 300 detects length L of document 400 in the conveyance direction. At this time, the CPU 300 detects the length L in the conveyance direction of the document 400 according to the procedure described with reference to FIG.

  At S1130, CPU 300 determines whether or not length L of document 400 in the conveyance direction is equal to or greater than short jam threshold LTH. If L ≧ LTH (YES in S1130), the process proceeds to S1140. If not (NO in S1130), the process proceeds to S1150.

  In S1140, CPU 300 continues the automatic document conveyance process. In S1150, CPU 300 stops the automatic document conveyance process. At this time, the CPU 300 stops the conveyance roller that has been rotated in the direction in which the document 400 is fed, and raises the paper feed roller 256. Further, the CPU 300 displays an error on the display panel 172 that a short jam has occurred. At this time, the document 400 is stopped at the position shown in FIG.

[Operation]
An operation of automatic document feeder 153 in image forming apparatus 150 according to the present embodiment based on the above-described structure and flowchart will be described. In the following description of the operation, it is assumed that the length of the original 400 in the conveyance direction is 90.0 mm, and L = 90.0 mm is detected in S1120.

<Single-sided scan mode, plain paper, normal image quality>
A case will be described in which the document 400 is set on the document tray 252 and the scan mode is set to the single-sided scan mode, the document thickness is selected to be plain paper (ordinary thickness), and the image quality is selected to be the normal image quality.

  When document 400 is set on document tray 252 of automatic document feeder 153 (YES in S1000), scan mode (single / double-sided), document thickness (thin paper / plain paper / thick paper) on display panel 172, An input screen for image quality (high image quality / normal image quality / low image quality) is displayed (S1010). The user inputs that the scan mode is set to single-sided scan mode, the original thickness is set to plain paper (ordinary thickness), and the image quality is set to normal image quality (medium speed) before the timeout occurs (NO in S1040). (YES in S1020). The display panel 172 displays that the scan mode is the single-sided scan mode, the document thickness is plain paper, and the image quality is normal image quality (medium speed) (S1030).

  If the user who thinks that this setting is correct depresses the “OK” key (YES in S1050) before the timeout occurs (NO in S1070), a copy ready screen is displayed on display panel 172 (S1060). Further, before the time-out (NO in S1100), if the user who wants to copy depresses the start button (YES in S1080), the short jam threshold LTH is in the single-sided scan mode, and the thickness of the document Is 91.2 mm, which is a threshold value when S is plain paper (normal thickness) and the image quality is normal image quality (medium speed) (S1090).

  While the document 400 is being automatically conveyed, the length L in the conveyance direction of the document 400 is detected as 90.0 mm (S1120). Since L (= 90.0 mm) <LTH (91.2 mm) (NO in S1130), this process is stopped (S1150). At this time, the document 400 is stopped at a position shown in FIG. 7A where the document 400 can be taken out easily and without being damaged.

<Single-sided scan mode, plain paper, low image quality>
A case will be described in which the original 400 is set on the original tray 252 and the scan mode is selected as the single-sided scan mode, the original thickness is selected as plain paper (normal thickness), and the image quality is selected as low image quality.

  When document 400 is set on document tray 252 of automatic document feeder 153 (YES in S1000), scan mode (single / double-sided), document thickness (thin paper / plain paper / thick paper) on display panel 172, An input screen for image quality (high image quality / normal image quality / low image quality) is displayed (S1010). Before the time-out is reached (NO in S1040), the user inputs that the scan mode is set to single-sided scan mode, the original thickness is set to plain paper (ordinary thickness), and the image quality is set to low image quality (high speed). (YES at S1020). The display panel 172 displays that the scan mode is the single-sided scan mode, the thickness of the original is plain paper, and the image quality is low (high speed) (S1030).

  If the user who thinks that this setting is correct depresses the “OK” key (YES in S1050) before the timeout occurs (NO in S1070), a copy ready screen is displayed on display panel 172 (S1060). Further, before the time-out (NO in S1100), if the user who wants to copy depresses the start button (YES in S1080), the short jam threshold LTH is in the single-sided scan mode, and the thickness of the document Is a plain paper (ordinary thickness), and is calculated to be 88.4 mm as a threshold value when the image quality is low (high speed) (S1090).

  While the document 400 is being automatically conveyed, the length L in the conveyance direction of the document 400 is detected as 90.0 mm (S1120). Since L (= 90.0 mm) ≧ LTH (88.4 mm) (YES in S1130), this process is continued (S1140).

  As described above, even the original 400 that cannot be automatically conveyed at high image quality (low speed) and normal image quality (medium speed) can be automatically conveyed at low image quality (high speed).

  In the case of scanning one side of a document 400 having a length L of 90.0 mm in the conveyance direction, when normal image quality (medium speed) is required for image quality, thin paper (threshold value LTH = 93.1 mm) and It cannot be automatically conveyed with plain paper (threshold value LTH = 91.2 mm), but can be automatically conveyed with thick paper (threshold value LTH = 88.4 mm).

  As described above, according to the automatic document conveyance device and the image forming apparatus including the automatic document conveyance device according to the present embodiment, the scan mode (single side / double side) that is a conveyance condition can be provided without arranging a large number of conveyance rollers. ), The threshold value is changed by appropriately setting the thickness of the original (thin paper / plain paper / thick paper) and the image quality (high image quality / normal image quality / low image quality). For this reason, the threshold value is uniformly determined by the distance between the conveyance rollers, and even if the document has a shorter conveyance direction length than the case where it is uniformly determined whether or not automatic conveyance is possible. It becomes possible to carry automatically.

-Second Embodiment-
Hereinafter, a second embodiment of the present invention will be described. The automatic document feeder according to the present embodiment and the image forming apparatus provided with the automatic document feeder are the same as those of the first embodiment described above and the image provided with the automatic document feeder. A program having a control structure partially different from the program executed in the forming apparatus is executed.

  The automatic document feeder 153 according to the present embodiment determines whether or not the document 400 is a business card according to the information input by the user, and changes the transport condition if it is determined to be a business card. Thus, the business card as the document 400 can be automatically conveyed.

  Here, a general business card size will be described. The size of a business card is generally 89.0 mm (length L in the transport direction) × 51.0 mm in the West, and No. 4 (91.0 (length L in the transport direction) mm × 55.0 mm in Japan. ). For example, such a business card cannot be automatically conveyed because the short threshold LTH is 91.2 mm when the “single-sided scan mode, plain paper, normal image quality (medium speed)” is set. When automatically conveying a business card, automatic document feeder 153 according to the present embodiment changes the conveyance condition to “single-sided scan mode, thick paper, low image quality (high speed)” for business card reading, and uses a short threshold value. The LTH is set to 85.7 mm so that the document 400 can be automatically conveyed.

  A control structure of a program executed by the CPU 300 to realize such a function will be described with reference to FIG. FIG. 12 corresponds to FIG. 11 and is a flowchart of a program executed by CPU 300 that controls automatic document feeder 153 according to the present embodiment.

  Referring to FIG. 12, in S2000, CPU 300 causes display panel 172 to display a selection screen for a business card reading mode and another reading mode.

  In S2010, CPU 300 determines whether business card reading mode has been selected or not. At this time, when the selection key corresponding to the business card reading mode displayed on display panel 172 is pressed, CPU 300 determines that business card reading mode has been selected. If it is determined that the business card reading mode has been selected (YES in S2010), the process proceeds to S2020. If not (NO in S1020), the process proceeds to S1040.

  In S2020, CPU 300 displays a mode confirmation screen on display panel 172. At this time, it is displayed that the document 400 that is automatically conveyed and read is a business card, and that the conveyance condition is set to “single-sided scan mode, thick paper, low image quality (high speed)”.

  In S2030, CPU 300 sets the conveyance condition to “single-sided scan mode, thick paper, low image quality (high speed)”. At this time, the short jam threshold LTH is 85.7 mm. The length L in the conveyance direction of business cards in Europe and America is 89.0 mm, and the length L in the conveyance direction of business cards in Japan is 91.0 mm. The conveyance conditions are set so that the short jam threshold LTH is shorter than the length L in the conveyance direction of the business card. Therefore, since the length L of the business card in the conveyance direction is longer than the short jam threshold LTH, the business card can be automatically conveyed.

  In S2040, CPU 300 lowers paper feed roller 256 and rotates it counterclockwise, and rotates other transport rollers in the direction of feeding document 400 to execute automatic transport processing.

  An operation of automatic document feeder 153 in image forming apparatus 150 according to the present embodiment based on the above-described structure and flowchart will be described.

  When the user sets a business card on document tray 252 (YES in S1000), a screen for selecting a business card reading mode and another reading mode is displayed on display panel 172 (S2000). When the user selects business card reading mode (YES in S2010), a mode confirmation screen is displayed on display panel 172 (S2020).

  When the user confirms and inputs (YES in S1050) and presses the start button (YES in S1080), the conveyance condition is set to “single-sided scan mode, cardboard, low image quality (high speed)” (S2030). At this time, the short jam threshold LTH is 85.7 mm, and the length L (89.0 mm, 91.0 mm) in the conveyance direction of the business card is longer than the short jam threshold LTH, so that the automatic conveyance processing is executed. (S2040).

  As described above, according to the automatic document feeder and the image forming apparatus including the automatic document feeder according to the present embodiment, when the user selects the business card reading mode when the document is a business card, the transport condition is “Single-sided scan mode, thick paper, low image quality (high speed)” is set. As a result, it is possible to automatically carry a Western business card or a domestic business card.

  A business card may be printed on only one side, or even if it is a business card printed on both sides, the information required by the user is often collected on one side (one is in Japanese and the other is Is a foreign language, one is company information and the other is a map, etc., and there are many cases where the thickness is more than a certain level and there are few cases where high image quality is required. "High speed)" does not cause a big problem.

-Third embodiment-
Hereinafter, a third embodiment of the present invention will be described. The automatic document feeder according to the present embodiment and the image forming apparatus provided with the automatic document feeder are the same as those of the second embodiment described above and the image provided with the automatic document feeder. A program having a control structure partially different from the program executed in the forming apparatus is executed.

  The automatic document feeder 153 according to the present embodiment determines whether or not the document 400 is a business card based on the width of the document presence / absence sensor provided on the document tray 252 and / or the document regulation guide. When the determination is made, the conveyance conditions are changed so that the business card as the document 400 can be automatically conveyed.

  A control structure of a program executed by the CPU 300 to realize such a function will be described with reference to FIG. FIG. 13 corresponds to FIG. 12 and is a flowchart of a program executed by CPU 300 that controls automatic document feeder 153 according to the present embodiment.

  Referring to FIG. 13, at S3000, CPU 300 detects the size of the document placed on document tray 252.

  In S3010, CPU 300 determines whether or not the document is a business card based on the size of the document. If it is determined that the document placed on document tray 252 is a business card (YES in S3010), the process proceeds to S3020. Otherwise (NO in S3010), this process ends.

  In S3020, CPU 300 displays a confirmation screen for business card reading mode on display panel 172. At this time, it is displayed that the document 400 set on the document tray 252 is automatically recognized as a business card and that the conveyance condition is set to “single-sided scan mode, thick paper, low image quality (high speed)”. The

  An operation of automatic document feeder 153 in image forming apparatus 150 according to the present embodiment based on the above-described structure and flowchart will be described.

  When the user sets a business card on document tray 252 (YES in S1000), the size of document 400 set on document tray 252 is detected (S3000). Since document 400 is a business card (YES in S3010), a confirmation screen for business card reading mode is displayed on display panel 172 (S3020).

  When the user confirms and inputs (YES in S1050) and presses the start button (YES in S1080), the conveyance condition is set to “single-sided scan mode, cardboard, low image quality (high speed)” (S2030). At this time, the short jam threshold LTH is 85.7 mm, and the length L (89.0 mm, 91.0 mm) in the conveyance direction of the business card is longer than the short jam threshold LTH, so that the automatic conveyance processing is executed. (S2040).

  As described above, according to the automatic document feeder and the image forming apparatus including the automatic document feeder according to the present embodiment, when the document set on the document tray is automatically detected as a business card When the user confirms that the business card is read, the conveyance condition is set to “single-sided scan mode, cardboard, low image quality (high speed)”. As a result, it is possible to automatically carry a Western business card or a domestic business card.

  The embodiment disclosed herein is merely an example, and the present invention is not limited to the above-described embodiment. The scope of the present invention is indicated by each claim in the claims after taking into account the description of the detailed description of the invention, and all modifications within the meaning and scope equivalent to the wording described therein are intended. Including.

DESCRIPTION OF SYMBOLS 150 Image forming apparatus 152 Image reading apparatus 153 Automatic document conveying apparatus 166 Operation apparatus 170 Operation panel 172 Display panel 300 CPU
302 HDD
304 I / O
306 ROM
308 RAM
310 Control unit

Claims (13)

An automatic document feeder that conveys a document to an image reading unit,
A plurality of rollers provided along the conveyance direction of the document for conveying the document;
A storage unit configured to store a threshold value for a conveyance direction of a document which can be automatically conveyed, which is set based on a distance between the rollers;
Setting means for setting the conveyance conditions for the document to be conveyed;
A determination means for determining that a document having a length in the transport direction shorter than the transport direction threshold value can be automatically transported based on the transport condition;
An automatic document feeder including control means for controlling the roller for feeding the document based on the determined result. The automatic document feeder further includes detection means for detecting the length of the document in the conveyance direction during document conveyance,
The determination means includes
Means for correcting the transport direction threshold to a correction threshold based on the transport conditions;
The automatic document feeder according to claim 1, further comprising means for determining that the document can be automatically conveyed when the detected conveyance direction length is longer than the corrected threshold value.   The automatic document feeder according to claim 1, wherein the setting unit includes a unit for setting the conveyance condition based on information input from a user. The automatic document feeder further includes a document detection means for detecting a document of a specific size whose transport direction length is shorter than the transport direction threshold before transport,
The determination means includes means for correcting the conveyance direction threshold value to a correction threshold value based on the conveyance condition,
The automatic document feeder according to claim 1, wherein the conveyance condition is set so that the corrected threshold value is shorter than a length in a conveyance direction of the document of the specific size.   The automatic document feeder according to claim 4, wherein the document detection unit includes a unit for detecting the document having the specific size based on information input from a user.   5. The automatic document feeder according to claim 4, wherein the document detection unit includes a unit for detecting a document of a specific size by detecting a size of a document placed on a document tray.   The automatic document feeder according to claim 4, wherein the document is a business card.   8. The control unit according to claim 1, wherein the control unit includes a unit for controlling the document to be stopped at a position where the document can be easily taken out when the determination unit determines that automatic conveyance is not possible. 9. Automatic document feeder. The automatic document feeder may include a reversing conveyance path for reversing and conveying a document,
2. The storage means includes means for storing a document conveyance direction threshold value that can be automatically conveyed, which is set based on a distance between rollers in a document conveyance path including the reverse conveyance path. The automatic document feeder according to claim 8.   The automatic document conveyance device according to claim 1, wherein the conveyance condition is a thickness of the document.   The automatic document conveyance device according to claim 1, wherein the conveyance condition is a conveyance speed of the document.   The automatic document feeder according to claim 11, wherein the document conveyance speed varies depending on a required image quality. An image forming apparatus comprising the automatic document feeder according to claim 1.

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