JP4732274B2 - Medium transport device and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more specifically, includes a medium conveying apparatus having medium identifying means for identifying the type of medium and the presence / absence of double feeding, and the medium conveying apparatus. The present invention relates to an image forming apparatus.

  Conventionally, the type identification of a sheet in a medium conveyance device used in an image forming apparatus is, for example, an optimum condition setting because an optimum condition regarding a copying condition, a printing condition, a printing condition, and an original reading condition varies depending on the type of the medium. To do. As the type identification method, a method performed by a user's type input operation and a method performed automatically by detecting a sheet are known. Further, the identification of double feeding (conveying in a state where two or more sheets are overlapped) by these medium conveying apparatuses is performed for the following reason. For example, when double feeding occurs during image formation, there is a possibility that winding around the transfer member or fixing member may occur due to separation of the overlapped sheets in the middle of conveyance. If this happens, there is a concern that the machine will be damaged significantly. Even if the sheets are discharged without being separated, the user must reconfirm the mixed state of the multi-feed sheets with respect to the bundle of sheets after the image formation, and extra work is generated. In particular, labor is increased after post-processing such as stapling. In order to avoid such a problem, it is necessary to stop image formation immediately when a double feed occurs and notify the user of the double feed occurrence. Therefore, the presence or absence of double feeding is identified for the control of the stop and notification. As this identification method, a method using a reflected light amount or a transmitted light amount is known.

  Among these, when the sheet type is identified by the above-described user type input operation, a user operation error such as “incorrect sheet information setting” or “incorrect setting of used sheet in tray” may occur. If this operation error occurs, a sheet different from the sheet setting recognized by the machine will be used. As a result, various problems such as a decrease in image fixing quality, a decrease in image quality due to a difference in transfer conditions, and the occurrence of sheet jams. There is concern about the occurrence of In the invention proposed in Patent Document 1, the type input operation by the user and the automatic identification of the sheet type are used in combination, so this concern is small. In addition to this, various techniques have been proposed. Note that the user's type input operation is publicly used, and is also described in Patent Documents 2 and 3.

JP 2003-29581 A JP 2002-311753 A JP 2003-101720 A

  Further, most of the conventional proposals are related to the accuracy improvement of each of the sheet type detection function and the double feed detection function. However, in a system that actually uses a sheet (medium), it is desirable to simplify the mechanism by organically linking the sheet type detection function and the double feed detection function.

  Therefore, the present applicant has proposed an image forming apparatus described in Japanese Patent Application No. 2005-286983 (hereinafter referred to as “prior application”). More specifically, in the image forming apparatus described in this prior application, the transmitted light amount measuring means is arranged so as to measure the transmitted light amount in the thickness direction of the medium on the conveyance path. Further, a measured value storage means for storing the result measured by the transmitted light amount measuring means, a medium setting means for presetting the type of medium to be used, and each medium set by the medium setting means Medium information storage means for storing information on the amount of transmitted light to be allocated. When the transmitted light amount is measured at the timing when the medium is transported, the medium type is determined for the first transported medium, and for the medium transported thereafter. By the medium identification means for performing double feed detection, the type discrimination function and the double feed detection function can be organically linked to simplify the mechanism.

  However, in the image forming apparatus described in the prior application, the medium discriminating unit performs medium type discrimination or double feed detection, and the medium determined to be abnormal according to a predetermined standard is the apparatus main body at the time when the determination is completed. Among them, for example, the conveyance is stopped at the registration unit. For this reason, it is necessary to remove the medium from the conveyance path having the resist portion. Therefore, there arises a problem that when the user removes the medium from the apparatus main body, the user is forced to be bothered by the same jamming process as a normal jam.

  The present invention is to improve the above-mentioned prior application in view of the above background. The object of the present invention is from the main body of the medium determined to be abnormal in the medium type discrimination or double feed detection by the medium identification means. It is an object of the present invention to provide a medium transport device that can easily perform the removal operation and an image forming apparatus including the medium transport device.

To achieve the above object, a first aspect of the invention, and can accommodate accommodating portion a plurality of media, and feeding means for feeding the said medium to the conveying path from the accommodating portion, the thickness direction of the medium conveyance path depending on the and placed transmitted light quantity measurement means to a transmitted light amount measuring, the transmitted light quantity measurement value memory means for storing the results of measurement by the measuring means, the medium used is nitrous et beforehand set information of the transmitted light amount storing a by which medium information memory means, together with the medium makes a transmitted light amount measured by the timing conveyed, and the amount of transmitted light measured at the transparent over-quantity measuring means, the medium information The medium type is determined or double feed is detected by comparing the transmitted light amount corresponding to the medium preset in the storage means or the transmitted light amount stored in the measured value storage means, and is determined timing Thus, are each selectively capable of executing a seed sheet determination and heavy feed detection, the certain determined timing is when the first medium is a timing which is conveyed to classify each said medium In addition, when the predetermined timing is a timing at which the medium after the first conveyance is conveyed, a medium conveyance device provided in the image forming apparatus main body having medium identification means for detecting double feeding In the above, after the first medium is fed out from the container by the feeding means, and the first medium type determination by the medium identifying means is completed, it is determined that the first medium type is normal according to a predetermined standard. Sometimes when the next medium is fed out from the container by the feeding means, and the type of the first medium is determined to be abnormal according to a predetermined standard Together does not perform the feeding of the next medium from the accommodating unit by the feeding means, the type discrimination or heavy feed detection result of the medium by said medium discrimination means, when it is determined that the abnormality according to a predetermined criterion, abnormal The medium determined to be conveyed to a predetermined retreat location provided in the main body of the image forming apparatus.
Further, the invention of claim 2, image forming means for forming an image on a medium, an image forming apparatus and a medium conveyance means for conveying the medium, as the medium conveying means, the medium feeding apparatus according to claim 1 It is characterized by comprising.
According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the image forming conditions of the image forming by the image forming means are switched in accordance with the result of the medium type determining by the medium identifying means. To do.
Further, the invention of claim 4, the image forming apparatus according to claim 2 or 3, on SL predetermined holding locations is characterized in that provided inside at least the apparatus main body.
The invention of claim 5 is the image forming apparatus according to claim 2, 3 or 4, upper Symbol predetermined holding locations is characterized in that provided in at least the apparatus main body outside.
Further, the invention of claim 6, claim 2, in the image forming apparatus 3, 4, or 5, the upper Symbol predetermined holding locations have two or more positions, which is estimated from the amount of transmitted light which is above Symbol measured Based on the type of the medium, the predetermined retreat location where the medium is transported can be selected.

  In the present invention, when the result of medium type discrimination or double feed detection by the medium identifying means is determined to be abnormal, the medium can be transported to a predetermined retreat location provided in the image forming apparatus main body. Thereby, by transporting the medium to a retreat place provided in a place where the medium can be easily removed in the image forming apparatus main body, the user can perform troublesome work such as normal jam processing, The medium can be removed from the apparatus main body.

  As described above, according to the present invention, there is an excellent effect that a medium determined to be abnormal can be easily removed from the apparatus main body by medium type discrimination or double feed detection by the medium identification unit.

  Hereinafter, an embodiment in which the present invention is applied to a copying machine as an image forming apparatus will be described. First, an outline of the copying machine will be described with reference to FIG. This image forming apparatus has a function as a so-called digital color copying machine that scans and reads a document, digitizes it, and copies it on a sheet. The copying machine also has a facsimile function for transferring image information of a document with a remote place and a so-called printer function for printing image information handled by a computer on a sheet.

  In FIG. 2, an image forming unit 1 is provided in the approximate center of the copying machine. A multi-stage feeding unit 2 is disposed below the image forming unit 1. In each stage of the feeding unit 2, a feeding tray 21 on which a bundle of sheets such as plain paper as a recording medium, an OHP sheet, and a second original drawing is stacked is disposed. The exceptional feeding tray 21 reaches the main body individually and can be detached, and a sensor for detecting this desorption is provided on the main body side. The feeding unit 2 is configured such that another feeding device 22 can be added as necessary. An openable / closable manual feed tray 120 is also provided on the right side of the image forming unit 1 in the drawing. As shown in the drawing, the sheet bundle can be stacked on the tray 120 with the upper portion moved away from the main body and opened. A sensor for detecting the presence or absence of a sheet on the tray 120 is also provided. Above the image forming unit 1, a reading unit 3 for reading a document is disposed. Further, on the left side of the image forming unit 1, a discharge tray 4 for discharging and storing sheets on which images are formed is disposed.

  In the image forming unit 1, image forming units 6 for each color for individually forming four color toner images are arranged in parallel so as to face the outer peripheral surface of the endless intermediate transfer belt 5. Each image forming unit 6 includes a drum-shaped photoconductor 61. Around each photoconductor 61, a charging device 62 that performs charging processing on the surface of the photoconductor 61, and an exposure device 7 that irradiates image information onto the surface of the photoconductor with a laser beam are disposed. Further, a developing device 63 for visualizing the electrostatic latent image formed on the surface of the photoconductor 61 and a cleaning device 64 for removing and collecting residual toner on the photoconductor 6 are disposed.

  In the reading unit 3, reading traveling bodies 32 and 33 each including a document illumination light source and a mirror for reading and scanning a document (not shown) placed on the contact glass 31 are reciprocally movable. Has been. Image information scanned by the reading traveling bodies 32 and 33 is read as an image signal into a CCD 35 installed behind the lens 34. The read image signal is digitized and subjected to image processing. Based on the image-processed signal, an electrostatic latent image is formed on the surface of the photoreceptor 61 by light emission of a laser diode LD (not shown) in the exposure device 7. The optical signal from the LD reaches the photosensitive member 61 via a known polygon mirror or lens. An automatic document feeder 36 for automatically feeding a document onto the contact glass 31 is attached above the reading unit 3.

  Around the intermediate transfer belt 5, a transfer device 51 for transferring a full color toner image formed on the intermediate transfer belt 5 to the sheet is disposed. Further, an intermediate transfer cleaning device 52 for removing and collecting the toner remaining on the surface of the intermediate transfer belt 5 after the full color toner image is transferred onto the sheet by the transfer device 51 is disposed.

  Next, an image forming process of the image forming apparatus will be described. In FIG. 2, each image forming unit 6 forms toner images of four colors on each photoconductor 61 at a predetermined timing in accordance with the rotation of the intermediate transfer belt 5 by a known electrophotographic process. First, in the yellow image forming portion (Y), a yellow toner image formed on the leftmost photoconductor is transferred to the intermediate transfer belt 5. In the magenta image forming section (M), the magenta toner image formed on the next photoconductor is superimposed on the yellow toner image and transferred to the intermediate transfer belt 5. In the cyan (C) image forming section, a cyan toner image formed on the next photosensitive member is further superimposed on the magenta toner image and transferred to the intermediate transfer belt 5. In the black (K) image forming unit, the black toner image formed on the right end photoconductor is superimposed on the cyan toner image and transferred to the intermediate transfer belt 5. As described above, the four color toner images formed on the respective photoreceptors are sequentially superimposed and transferred to form a full color toner image on the intermediate transfer belt 5.

  On the other hand, in parallel with the image forming operation of the full-color toner image on the intermediate transfer belt 5, the sheets are sequentially separated and fed one by one from the selected feeding tray 21 of the feeding unit 2. That is, in the feeding unit 2 shown in FIG. 3, the sheet bundle is stacked on the bottom plate 24 that is rotatably supported by the feeding tray 21. By the rotation of the bottom plate 24, the uppermost sheet of the sheet bundle is raised to a position where it can contact the pickup roller 25. This uppermost sheet is fed by the rotation of the pickup roller 25 and separated into one sheet by the reverse roller 27. Then, the uppermost sheet separated into one sheet is sent out from the feed tray 21 by the rotation of the feed roller 26, and to the registration roller 23 shown in FIG. It is conveyed.

  The sheet separated and conveyed as described above abuts against the nip of the registration roller 23 and is temporarily stopped after being conveyed. The registration roller 23 is controlled to start rotating at a timing so that the positional relationship between the full-color toner image formed on the intermediate transfer belt 5 and the leading edge of the sheet is a predetermined position. By the rotation of the registration roller 23, the waiting sheet is fed again. As a result, the full color toner image formed on the intermediate transfer belt 5 is transferred to the predetermined position of the sheet by the transfer device 51.

The sheet on which the full-color toner image is transferred in this manner is sent to the fixing unit 8 on the downstream side of the conveyance path. The fixing unit 8 fixes the full-color toner image transferred by the transfer device 51 on the sheet. The sheet on which the full color toner image is fixed is discharged and stored in the discharge tray 4 by the discharge roller 41.
Here, when image formation is performed on both surfaces of the sheet, the sheet is branched by the branching unit 91 and is passed through the double-side device 9 so that the front and back of the sheet are reversed. The sheet with the front and back sides abutted against the nip of the registration roller 23 is corrected for skew, and image formation on the back surface is performed in the same manner as in the image formation on one side described above.

Next, the medium identification device will be described. FIG. 3 shows an example of the installation form of the mechanical elements of the medium identification device.
A light emitting unit 110 and a light receiving unit 111 constituting a transmitted light amount measuring unit are provided on the conveyance path on the downstream side in the sheet conveyance direction of the feeding tray 21. Then, the transmitted light amount measuring means is fed out in order from the uppermost sheet of the sheet bundle 115 placed on the bottom plate 24 of the feeding tray 21 by the pickup roller 25 as feeding means, and the feeding roller 26 and the reverse roller 27. And the amount of transmitted light of the sheets separated and conveyed one by one is measured for each sheet. The installation location of the transmitted light amount measuring means is not particularly limited as long as it is on the conveyance path from the feeding section to the image forming section. However, if the apparatus has a plurality of conveyance paths, one is located near the registration roller where they are gathered. It is desirable in terms of cost.

  The light emitting means 110 outputs a predetermined amount of light. The light receiving unit 111 detects the amount of light output from the light emitting unit 110. The light emitting means 110 and the light receiving means 111 are arranged so as to sandwich the sheet 114 to be identified, and the amount of transmitted light in the thickness direction of the sheet can be measured. In the present embodiment, a control unit corresponding to each of the light emitting unit 110 and the light receiving unit 111 is provided, and the transmitted light amount of the conveyed medium is measured, and the type of the medium is discriminated from the light amount level, overlap feed, etc. The state of the medium is detected.

FIG. 4 illustrates main control units in the copying apparatus.
The engine control unit 101 mainly performs basic control of operations of main parts of the copying machine such as the image control unit 1, the feeding unit 2, and the fixing unit 8. An external host computer 103, a display unit 104, an input unit 105, and the like are connected to the controller control unit 102, and external information necessary for operation is obtained and managed. Furthermore, the controller control unit 102 provides necessary information to the engine control unit 101 and manages the movement of the entire system. The display unit 104 can be configured using a display of an operation panel. In addition to being able to be configured with operation buttons provided on the operation panel, the input unit 105 can be used as a part or all of the input unit 105 when the display is configured with a touch panel instead.

  A storage unit (medium information storage unit or measurement value storage unit) and various determination units (calculation unit) for various information management of the medium identification device are provided in the engine control unit 101, the controller unit 102, and the feeding unit 2. Any one of the included control units or two or more storage units and calculation units are configured. The medium setting means for presetting the type of sheet to be used is the input section 105 and a predetermined memory section for storing the setting contents in the memory section as the medium information storage means while accepting the input from now on. It can be composed of a recorded control program and arithmetic means for executing this program. In the case of a control program that provides guidance for the setting operation while performing a constant display on the display unit 104, the display unit 104 is also a constituent element. As a specific configuration of such medium setting means, the above-described conventional publicly-known technique, the technique disclosed in Patent Documents 2 and 3, and the like can be used. The control program that constitutes the medium setting means and the calculation unit that executes the control program may be one of the control units included in the engine control unit 101, the controller unit 102, and the feeding unit 2, or two or more storage units and calculation units. Configure the part.

FIG. 5 is a flowchart of medium identification control.
First, the type of sheet to be used is set by the medium setting means (S′1). Thus, the range value information R1 to R4 corresponding to the selected sheet type is called by the transmitted light amount table for each medium stored in advance in the medium information storage means, for example, the table of the contents of Table 1. The comparison value (range value) Rz for determining the medium type is set (S′1). Here, the reason why Rz is set as the range value is that, for example, even though it is plain paper, there are various types of plain paper level media in the market. Therefore, if the measured transmitted light amount falls within a certain range, it is regarded as plain paper, so that a large amount of information and complicated management thereof can be avoided.

  When the medium information is set, the comparison value Y is reset (S'2). This comparison value Y stores the amount of transmitted light of the medium measured last time, and is a comparison parameter used for determination of double feeding. Next, when the conveyance of the medium is started at an arbitrary timing (S′3), the amount of transmitted light is measured at a predetermined timing, and the value is temporarily stored in the memory as a measured value X (S′4). . Up to this point, a series of processes up to the measurement of the transmitted light amount is performed.

  Next, it is determined whether or not the conveyed medium is the first sheet. Based on this determination, it is determined whether to perform medium type determination or double feed determination. This is determined by whether or not the comparison value Y is set (S'5). In the case of the first sheet, when the medium information is set in preparation before the start of conveyance (S'1), the Y value is reset (comparison value Y = NULL) accordingly (S'2). As a result, it can be regarded as the first sheet, and in this case, since it is a medium type determination target (Y in S′5), the measured value X and the range value information Rz are compared (S′6). ).

  When it is considered that replenishment due to a shortage of sheets (paper end or the like) or sheet resetting has occurred, it is not known whether the next sheet to be replenished is the same level. That is, it is a case where it seems that this replenishment or resetting has occurred among the exceptional feeding trays 21 and manual feed trays 120 of the feeding unit 2. Specifically, at the timing when the removal or removal of the feeding tray 21 is detected or the presence of a sheet is detected by the manual feed tray 120 and the presence of a sheet is detected thereafter, the stored sheet is replaced and another type of sheet is detected. It may have become a thing. Therefore, it is desirable to reset the Y value also in these cases. In addition, the timing at which the apparatus main body is turned off or turned on after being turned off is also the timing at which sheets may be exchanged for the trays 21 and 120 during the power interruption. Therefore, it is desirable to reset the Y value even at this timing. The reset means is configured by the control for performing such reset, the program of S3, and the arithmetic unit for executing the program.

Then, the measured value X and the range value information Rz are compared (S′6). If X is within the range of Rz, it is determined that the measured sheet matches the sheet setting, and the measured value X is set to the comparison value Y (S′10), and the carrying operation is continued. When X is out of the range of Rz, it is determined that the sheet is different, and the conveyance operation is stopped after conveying the sheet to a predetermined evacuation place described later, and there is a setting difference or a sheet setting difference. A warning is given to the occurrence (S'12).
The comparison value Y when the measurement value X is set to the comparison value Y corresponds to the measurement result stored in the measurement value storage means, and a memory unit for storing the comparison value Y is provided in the measurement value storage means. Equivalent to.

  When it is determined that the conveyance is continued (N in S′11), the process returns to the medium conveyance operation (S′3) again, and the transmitted light amount of the next sheet is measured (S′4). In determining whether or not the medium is the first sheet (S′5), since the comparison value Y, which is the measurement value of the previous sheet, is set, it is regarded as the second (second) measurement. (N in S′5), the process proceeds to the double feed determination flow (S′8). Here, the comparison value Y (front sheet) and the rear measurement value X (subsequent sheet) are compared. Normally, the amount of transmitted light when double feed (multiple feed) occurs is theoretically attenuated to about half or less than that of a single sheet when two sheets are overlapped. Using this, double feed is detected. As the comparison value Y, a value having a certain range is used in consideration of variations in the measurement value for one sheet. For example, when the measured value of the front sheet is X, the misdetection at the time of 1 sheet → 1 sheet is reliably prevented by setting the comparison value Y = X ± 30%. Then, when the measured value X is significantly different from the comparison value Y, for example, when it is significantly reduced (N in S′8), it is determined that double feeding is performed (S′9), and a predetermined evacuation place described later is taken. After the sheet is conveyed, the conveying operation is stopped, and a warning is given that overlap feeding has occurred (S′12). Further, the control flow is repeated while the sheet is continuously conveyed. During this repetition, the step (S′4) for measuring the amount of transmitted light and the step (S′10) for setting the measurement value X to the comparison value Y are also repeated. Every time the sheet is measured by the transmitted light amount measuring means, the stored contents are rewritten. Further, when the series of conveying operations is normally completed (Y in S′11), when the sheet setting is not changed or the sheet is not changed thereafter, the Y value is not reset to simplify the control. I am trying.

Usually, a sheet tray of a copying machine or the like can store a certain amount of sheets with a single replenishment. From this, as long as the type of the first sheet is detected, there is no change in the setting of the sheet type, replacement of sheets, etc., even if the printing operation (normal end) is repeated many times in the middle. For the second and subsequent sheets, only a double feed detection is performed, so that the system can be realized sufficiently.
With the control flow described above, it is possible to make a mode determination such as medium type detection when it is determined that the first sheet (first time) is measured, and double feed detection when it is determined that the second sheet (second time) or later is measured. .

  In addition to the above-described medium identification control, the copying machine according to the present embodiment performs control for switching image forming conditions according to the type of sheet used for copying. Specifically, at least heat is used as a fixing device when the amount of heat is switched (variable depending on the lamp light amount and the sheet conveyance speed during fixing). In addition, switching of the transfer electric field intensity used for transfer, switching of the sheet conveyance speed and sheet interval (related to switching of heat amount in fixing) is also performed. Instead of or in addition to this, other image forming conditions can be switched. The setting result of S2 can be used for recognizing the type of sheet to be used for this switching control. The feeding unit 2 includes a multi-stage tray 21 and a manual feed tray 120. Therefore, a memory for storing the set sheet type is prepared for each tray. Then, for the tray selected to be used, the type of the sheet accommodated in the tray is read from this memory, and the image forming condition is switched to the appropriate one. For this switching, an optimum image forming condition for each sheet type is stored in a memory in a table format or the like.

Hereinafter, characteristic parts related to the present invention will be described.
As shown in FIG. 2, the copying machine of this embodiment includes a duplex unit 122 and a reversing tray 123 that is included therein. FIG. 6 shows a state where the duplex unit 122 is pulled out from the apparatus main body.

  As for the handling of the sheet determined to be abnormal in the type identification, it is desirable that the sheet is processed without bothering the user by discharging it to the outside of the main body apparatus or the like. Examples of the outside of the main body device include a discharge tray 4 and a discharge tray of an optional post-processing device. However, it is not desirable for the output tray 4 to contain a normal output until then and a sheet that has been determined to be abnormal. Therefore, by providing a retreat place inside the apparatus main body, the above problem can be solved and the user can make the remaining paper process as easy as possible. As an example, the reversing tray 123 configured in the duplex unit 122 can be set as a retreat location.

In addition, as shown in FIG. 3, when the transmitted light amount measurement unit determines that the type identification of the sheet 114 is abnormal, the sheet type is estimated from the measured transmittance light amount Rz, and a suitable retreat location. Select. For example, as shown in Table 2, if the measured transmittance is a sheet up to level 1 of thick paper including OHP, continuous conveyance to the reverse tray 123 is performed after the abnormality determination. The user can easily perform the remaining paper processing on the reversing tray 123 by pulling out the duplex unit 122 from the apparatus main body as shown in FIG. In addition, since the machine can be restored on the delivery tray 4 without removing abnormal sheets, it is not possible to reliably prevent the user from forgetting to remove abnormal sheets. Can be surely processed.

  However, in the case of ultra-thick paper that is physically difficult to enter the reversing tray 123, it is desirable to avoid retracting the sheet to the reversing tray 123. This is because there is a concern about damage to the apparatus main body that may occur when the thick paper 2 is retracted to the reverse tray 123. Therefore, in this embodiment, if the conveyed sheet is ultra-thick paper, for example, the thick paper 2 level shown in Table 2, the sheet is discharged onto the discharge tray 4 without being conveyed to the reverse tray 123.

Next, a description will be given of a configuration in which the feeding timing of subsequent sheets that are continuously fed out from the storage unit can be changed following the sheet that is the target of medium type discrimination or double feed detection.
FIG. 7 shows a sheet interval in a normal continuous conveyance state. The sheets 114, 114a and 114b on the feeding tray 21 of the sheet length Lp that are sequentially fed out from the feeding tray 21 are fed out on the conveying path at a constant interval δ and guided to the image forming unit. Here, when the distance from the feeding tray 21 to the transmitted light amount measuring unit is long, when the leading sheet 114 reaches the transmitted light amount measuring unit, the subsequent sheet 114a has already been conveyed on the conveyance path. In this state, when an abnormality is detected by medium identification, the machine is stopped. In this case, once fed out, the sheet 114a is processed as remaining paper. Further, when the image transferred to the subsequent sheet 114a has already been transferred onto the intermediate transfer belt 5 shown in FIG. 2, wasteful toner consumption occurs, and the durability of the intermediate transfer cleaning device 52 is reduced. Also invite.

  Therefore, in the present embodiment, the above-described problem is avoided by widening the interval between the first sheet to be subjected to medium identification and the subsequent sheet. FIG. 8 shows an example of the sheet interval when the interval between subsequent sheets is increased. By adjusting the feeding timing of the succeeding sheet, the interval between the sheet to be subjected to type discrimination or double feed detection and the succeeding sheet to be continuously fed is increased by a predetermined amount. As a result, even when the leading sheet 114 reaches the measurement unit, the subsequent sheet does not exist on the conveyance path. That is, even if the preceding sheet 114 is determined to be abnormal, no wasted sheet is generated. Further, the timing of exposure, development, transfer, etc. of the entire image forming unit 1 in FIG. 2 is also set so that the interval between the images corresponding to the preceding sheet 114 and the succeeding sheet 114a is opened by a certain amount in advance. Change according to the feeding timing of the sheet. For example, various timings are changed so that the transfer of the image corresponding to the sheet 114a is started simultaneously with the start of feeding of the succeeding sheet 114a. Thereby, useless toner consumption and cleaning burden can be reduced.

  The conditions of the image forming apparatus in which such a timing change is effective are related to the positional relationship between the feeding tray 21 and the transmitted light amount measurement unit. That is, as shown in FIG. 7, when the installation interval L, the sheet length Lp, and the sheet interval δ are satisfied, the condition that satisfies the condition of L> (Lp + δ) is effective. That is, the transmitted light amount measuring means is disposed in the vicinity of the upstream side in the sheet conveying direction of the registration roller 23 shown in FIG. 2 and includes a plurality of sheet storage portions on the lower side of the apparatus main body. That is, the sheets fed from these sheet storage units are transported through a transport path that is long to some extent, which is very effective.

  Further, the feeding timing of the succeeding sheet following the sheet that is the execution target of type discrimination or double feed detection is the timing after the time point when it is determined that the execution target sheet is normal or abnormal. Since such timing is determined in advance for each of a plurality of sheet feeding units, the timing can be set in advance for each sheet feeding unit. Further, the control may be performed so that the subsequent sheet is fed out when it is determined to be normal upon receiving the result of the actual determination as normal or abnormal, and the above feeding is not performed when it is determined as abnormal. Furthermore, the feeding timing of a sheet subsequent to the target sheet may be changed only for one of the two types of type discrimination and double feed detection, for example, only for type discrimination.

  Here, attention is paid to the case where the type determination is performed only for the first sheet, the double feed detection is performed for the second and subsequent sheets, and the above-described feeding timing is changed for the second and subsequent sheets. In this case, the initial continuous productivity cannot be ensured by providing a feeding interval between the first sheet, which is the first sheet, and the subsequent sheet, which is the second sheet. For this reason, it is inevitable that productivity in the initial stage of printing will be reduced. This becomes more prominent as the installation interval L becomes longer. Therefore, it is desirable to provide a mode selection unit that allows the user to arbitrarily select whether or not to perform an operation for separating sheets, that is, a feed interval extension mode ON / OFF, in preparation for the case where productivity is important. As a result, if the user who focuses on productivity turns off the feeding interval extension mode, sheets are fed from the first stage while maintaining the same sheet interval δ as during normal continuous feeding. The nature will not decline. Such a mode selection selection unit can be constituted by a normal operator operation unit and a control unit that performs sequence control of each unit such as the image forming unit 1 using a signal from the operation unit.

FIG. 1 is a flowchart illustrating an example of feeding operation control according to this embodiment.
Prior to the start of printing, whether or not to perform a save operation is set in advance by the save mode setting means. Similarly, whether or not to execute the feeding interval extension mode setting means is selected as a mode for increasing the feeding interval. After the start of the printing operation, based on the determination of the feeding interval extension mode setting means (S1), if the setting is ON, the feeding interval extension mode is applied, and only the first sheet is fed. Start (S2). When the setting is OFF, continuous feeding is performed at a normal feeding interval (S5) until feeding is completed (Y in S6).

  When the feeding interval extension mode is ON, the next operation is performed depending on whether or not the medium detection for the type detection in the preceding first sheet is completed (Y in S3) and whether the identification result is normal determination. Determine (S4). If the identification result is normal (Y in S4), the feeding of the next sheet is continued at the normal feeding interval (S5). Thereafter, the sheet is fed at a normal sheet interval.

  If an abnormality is determined in the identification result (N in S4), it is confirmed whether the save mode is ON (S7). If the save mode is not ON (N in S7), the machine is stopped (S12). Then, a warning is given that a setting difference or a sheet difference has occurred, and the position where the sheet is stopped is displayed (S13). If the retreat mode is ON (Y in S7), the first image forming process is canceled (S8), and a retreat location suitable for the estimated sheet type is selected (S9). Note that it is desirable to temporarily stop the conveyance of the sheet at the time when abnormality is determined and perform image forming cleaning. Then, if it is a sheet of thick paper 2 level shown in Table 2, it is continuously conveyed to the discharge tray 4 (S10). (S11). After the evacuation is completed, the machine is stopped (S12). Then, a warning is given that a setting difference or a sheet difference has occurred, and the user's processing is accurately guided by notifying the save location of the sheet (S13).

  According to this control, if the medium identification of the leading sheet is completed and it is not determined to be normal, the succeeding sheet is not fed, and therefore the succeeding sheet 114a remains on the feeding tray 21 even if an abnormality is determined. Stay on. As described above, the interval between the sheet that is the object of medium identification that is fed in advance and the sheet that is fed subsequently is set wider than in normal continuous conveyance. Thereby, even when the medium identification abnormality is detected and the conveying operation is stopped, it is possible to prevent the useless sheet from remaining in the apparatus main body. Thereby, it is possible to eliminate troublesomeness such as resource saving and remaining paper processing. Further, eliminating unnecessary images on the intermediate transfer belt 5 leads to reduction in toner consumption and improvement in durability of the cleaning mechanism. In addition, when it is determined that the sheet to be previously identified as a medium identification target is normal, the next sheet can be fed and executed so that it can be reliably performed with simple control. become. Further, there is provided a selection means for allowing the user to arbitrarily select whether or not to execute an operation for separating the sheets (initial productivity is lowered). Thereby, when it is not desired to reduce the initial productivity, the normal feeding mode can be applied.

As described above, according to the present embodiment, the feeding tray 21 is capable of accommodating a plurality of media, the pickup roller 25 is a feeding means for feeding a sheet which is a medium to the conveying path from the feeding tray 21, the transport path and placed transmitted light quantity measurement means so as to measure the amount of transmitted light in a thickness direction of the sheet over preparative, the measured value storing means for storing the results of measurement by the transmitted light quantity measurement means, used is set in advance Medium information storage means for storing information on the amount of transmitted light corresponding to the sheet, and measuring the transmitted light amount at the timing when the sheet is conveyed, and the transmitted light amount measured by the transmitted light amount measuring means, The type of the sheet is determined by comparing the transmitted light amount corresponding to the sheet preset in the medium information storage means or the transmitted light amount stored in the measurement value storage means. Can perform double feed detection and selectively execute type discrimination and double feed detection according to a predetermined timing, and the predetermined timing is the timing at which the first sheet is conveyed. An image having medium identifying means for determining the type of sheet in some cases, and for detecting multi-feed when the predetermined timing is a timing at which a sheet after the first conveyance is conveyed In the feeding apparatus, which is a medium conveying apparatus provided in the copying machine main body, which is a forming apparatus, the first sheet is fed from the feeding tray 21 by the pickup roller 25, and the type identification of the first sheet is completed by the medium identifying means. Thereafter, when it is determined that the first sheet type is normal according to a predetermined standard, the sheet is fed by the pickup roller 25. Feeding the next sheet from the tray 21, along with not perform the feeding of the next sheet from the feed tray 21 by the pickup roller 25 when the type of the first sheet in accordance with predetermined criteria is determined to be abnormal, medium identification means When the result of the sheet type discrimination or double feed detection by is determined to be abnormal according to a predetermined standard, the sheet determined to be abnormal is conveyed to a predetermined retreat location provided in the copier body. Thereby, the user can transfer the sheet to a retreat place provided at a place where the sheet can be easily removed from the copying machine body, so that the user can remove the sheet from the copying machine without performing troublesome operations such as normal jam processing. It can be easily removed from the body . Also, the first preceding sheet which is a sheet, complete medium identification, and, if it is determined to be normal, because it does not feed the succeeding sheet is the next sheet, the preceding sheet abnormality determination and Even in this case, the subsequent sheet remains on the feeding tray 21. In this way, the interval between the sheet that is the object of medium identification that is fed in advance and the sheet that is fed subsequently is made wider than in normal continuous conveyance. By doing so, it is possible to prevent the useless sheet from remaining in the apparatus main body even when the medium identification abnormality is detected and the conveying operation is stopped. Thereby, it is possible to eliminate troublesomeness such as resource saving and remaining paper processing.
Further, according to the present embodiment, the predetermined retreat place is at least on the inside of the apparatus main body, for example, on the reversing tray 123 provided in the duplex unit 122. Accordingly, the user can easily perform the remaining paper processing on the discharge tray 123 by pulling out the duplex unit 122 from the apparatus main body.
Further, according to the present embodiment, by setting the predetermined evacuation place at least outside the apparatus main body, for example, the discharge tray 4, the sheet determined to be abnormal is conveyed outside the apparatus main body. Therefore, a user can easily process a sheet that has been determined to be abnormal without bothering hands.
Further, according to the present embodiment, there are two or more evacuation places, and a predetermined evacuation place to which the sheet is conveyed is selected based on the type of the sheet estimated from the measured transmitted light amount. It is configured as possible. For example, if the measured transmittance is OHP, a second original, plain paper, cardboard 1 or the like, the sheet is conveyed to the reversing tray 123 where the user can easily perform the remaining paper processing. Further, in the case of ultra-thick paper having a level of thick paper 2 that is difficult to enter the reversing tray 123, the super-thick paper is discharged onto the discharge tray 4. As a result, damage to the apparatus main body that may occur when the ultra-thick paper is retracted to the reverse tray 123 can be suppressed.

  Although the present embodiment is an example in which the present invention is applied to a feeding device of a copying machine, the present invention can also be applied to a document feeding device in an automatic document feeder 36 of a copying machine. It can also be applied to a printer, a printing machine, or a scanner.

The flowchart of control of evacuation operation | movement. 1 is a schematic configuration diagram of a copier according to an embodiment. The schematic block diagram of a feeder. The block diagram of the electric transmission part of a copying machine. The flowchart of control of medium identification. FIG. 3 is a schematic configuration diagram when the duplex unit is pulled out of the apparatus main body. FIG. 6 is an explanatory diagram illustrating sheet intervals in a normal continuous conveyance state. Explanatory drawing in the case of conveying by expanding the space | interval of the sheet | seat of a head sheet and a succeeding sheet.

Explanation of symbols

4 Discharge tray 21 Feed tray 23 Registration roller 25 Pickup roller 26 Feed roller 27 Reverse roller 101 Engine control unit 102 Controller control unit 104 Display unit 105 Input unit 110 Light emitting unit 111 Light receiving unit 114 Sheet 114a Subsequent sheet 115 Sheet bundle 122 Duplex unit 123 Reverse tray

Claims (6)

An accommodating portion capable of accommodating a plurality of media;
A feeding means for feeding out the medium from the container to the transport path;
And it placed transmitted light quantity measurement means to measure the conveyance amount of transmitted light in a thickness direction of the medium path,
A measurement value memory means for storing the results of measurement by the transmitted light quantity measurement means,
And a medium information memory means for storing Oh et beforehand information of transmission light depending on the medium used has been set,
Together with the medium makes a transmitted light amount measured by the timing conveyed, the transparent and the amount of transmitted light measured by the excessive light quantity measurement means, the amount of transmitted light or measured value corresponding to the medium that is set in advance in the medium information storage means By comparing with the amount of transmitted light stored in the storage means, the type of the medium is detected or the double feed is detected, and the type determination and the double feed detection are selectively executed according to a predetermined timing. Is possible,
If the predetermined timing is the timing when the first medium is transported, the medium type is determined, and the predetermined timing is determined when the medium after the first transport is transported. In the medium conveying device provided in the image forming apparatus main body, having medium identifying means for detecting double feeding when it is time to come,
When the first medium is determined from the storage unit by the supply means and the first medium type is determined by the medium identification means, and the first medium type is determined to be normal according to a predetermined reference, the The next medium is fed out from the storage unit by the feeding unit, and when it is determined that the type of the first medium is abnormal according to a predetermined standard, the next medium is not fed out from the storage unit by the feeding unit, and
The medium type judgment or heavy feed detection results by said medium discrimination means, when it is determined that the abnormality according to a predetermined criterion, a predetermined provided with abnormality determined as the said medium to the image forming apparatus main body shelters A medium conveying apparatus characterized in that the medium is conveyed. Image forming means for forming an image on a medium;
In the image forming apparatus and a medium conveyance means for conveying the medium,
As the medium conveying means, the image forming apparatus characterized by comprising a medium transport device of claim 1.   The image forming apparatus according to claim 2.
An image forming apparatus, wherein image forming conditions for image formation by the image forming unit are switched in accordance with a result of the medium type determination by the medium identifying unit. The image forming apparatus according to claim 2 or 3,
On SL predetermined holding locations, the image forming apparatus, characterized in that provided inside at least the apparatus main body. The image forming apparatus according to claim 2, 3 or 4,
On SL predetermined holding locations, the image forming apparatus, characterized in that provided in at least the apparatus main body outside. The image forming apparatus according to claim 2, 3 , 4, or 5.
On SL predetermined holding locations have two or more places,
Based on the type of the medium was estimated from the top Symbol measured amount of transmitted light, the image forming apparatus, characterized in that the predetermined holding locations where the medium is conveyed can be selected.

Images