Image forming apparatus and method for controlling supply means used in said apparatus

Abstract

To provide an image forming device efficiently suppressed in probability of occurrence of sheet jam and a control method of supply means used therefor.SOLUTION: An image forming device has storing means storing sheets, supply means supplying the sheets one by one from the storing means to a sheet transportation path, sheet detecting means arranged on the sheet transportation path and detecting passage of the sheets, and control means controlling the supply means. When sheet supply time from the start of the sheet supply by the supply means until detection of the sheet by the sheet detecting means is less than a prescribed reference value, the control means determines occurrence of multiple-sheet feeding, and allows the supply means to supply subsequent sheets, after holding until passage of prescribed extended stand-by time longer than prescribed ordinary stand-by time.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a multifunction machine, a printer, or a facsimile machine. [Background technology]

[0002] As a technique for reducing the probability of sheet jams occurring on the sheet transport path in an image forming apparatus, a control for adjusting the interval between sheets is known. For example, a control for stopping the transport roller and the paper feed roller when the interval between sheets is narrow as in Patent Document 1, and a control for correcting the rotation timing of the pickup roller based on the delay time of the transport of the sheets as in Patent Document 2 are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-44757 A [Patent Document 2] JP 2013-49532 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the example disclosed in Patent Document 1, there is a problem that the processing efficiency may decrease due to the stop of the conveying roller and the paper feed roller. Also, in the example disclosed in Patent Document 2, for example, when the pickup roller pulls out the sheets in a state where multiple sheets are overlapped, that is, when so-called sheet dragging occurs, there is a problem that it is difficult to adjust the supply timing of the sheet that has already jumped out of the pickup roller by controlling the pickup roller.

[0005] The present invention has been made to solve the above-mentioned problems in the conventional art, and aims to provide an image forming apparatus and a control method for a supply means used in the apparatus, which can efficiently reduce the probability of sheet jamming even when a sheet is fed early. [Means for solving the problem]

[0006] In order to achieve the above object, the image forming apparatus described in the present application includes a storage unit for storing sheets, a supply unit for supplying the sheets one by one from the storage unit to a sheet transport path, a sheet detection unit disposed on the sheet transport path for detecting the passage of the sheets, and a control unit for controlling the supply unit. A notification unit capable of notifying a user of information; and wherein the control means determines that a sheet has been conveyed while the sheet is being conveyed, when a sheet conveyance time from when the sheet conveyance means starts to convey the sheet to when the sheet detection means detects the sheet is less than a predetermined reference value, and causes the supply means to supply a subsequent sheet after waiting until a predetermined extended standby time that is longer than a predetermined normal standby time has elapsed. and when a supply delay for causing the supply means to supply a subsequent sheet is executed a predetermined number of times in succession after waiting until the extended waiting time has elapsed, the notification unit issues a notification to prompt a user to turn over the sheet surface. .

[0007] In addition, the image forming apparatus may further include a registration roller arranged on the sheet transport path, the supply means has a supply roller that rotates by receiving a driving force, the sheet detection means is a pre-registration sensor arranged upstream of the sheet transport path from the registration roller, the sheet supply time is the time from when the supply roller starts to rotate to when the pre-registration sensor detects the sheet, and the control means may wait until the extended waiting time has elapsed after the registration roller starts to rotate, and then cause the supply means to supply a subsequent sheet.

[0009] In addition, the image forming apparatus may further include a size discrimination means for discriminating the size of the sheet, and the control means may change the normal standby time and the extended standby time based on the size of the sheet discriminated by the size discrimination means.

[0010] In addition, the image forming apparatus may further include a temperature and humidity measuring means for measuring the temperature and humidity around the storage means, and the control means may change the normal standby time and the extended standby time based on the measurement results of the temperature and humidity measuring means.

[0011] The control method of the supplying means described in the present application is a control method of the supplying means which supplies sheets one by one to a sheet transport path, and when the time from when the supplying means starts supplying the sheet to when the sheet passes a predetermined position on the sheet transport path is less than a predetermined reference value, it is determined that a sheet has been brought forward, and after waiting until a predetermined extended waiting time that is longer than a predetermined normal waiting time has elapsed, the control method causes the supplying means to supply a subsequent sheet. and when a supply delay for causing the supply means to supply a subsequent sheet is executed a predetermined number of times in succession after waiting until the extended waiting time has elapsed, a notification is given to a user to urge the user to turn the sheet surface upside down. The present invention is characterized by the following: Effect of the Invention

[0012] According to the present invention, the probability of occurrence of a sheet jam can be effectively reduced. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view showing a configuration of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing a part of a control configuration of the image forming apparatus according to the first embodiment. [Diagram 3] 5 is a flowchart showing a part of a processing procedure performed by a control unit in the first embodiment. [Figure 4] 4 is a table showing a part of the processing contents by a control unit in one example of the first embodiment. [Diagram 5] 11 is a schematic diagram showing a state in which a plurality of sheets are stacked in a sheet cassette such that the burrs of each sheet face upward. FIG. [Figure 6]11 is a schematic diagram showing a state in which a plurality of sheets are stacked in a sheet cassette such that burrs of each sheet face downward. FIG. [Figure 7] FIG. 11 is a block diagram showing a part of a control configuration of an image forming apparatus according to a second embodiment. [Figure 8] FIG. 11 is a block diagram showing a part of a control configuration of an image forming apparatus according to a third embodiment. [Figure 9] FIG. 11 is a diagram showing an example of a correction table in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the same components in the embodiments described below are designated by the same reference numerals, and redundant descriptions of those components will be omitted.

[0015] (Embodiment 1) -Overall configuration of image forming apparatus- First, the overall configuration of the image forming apparatus A in the first embodiment will be described.

[0016] FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus A in the first embodiment. FIG. 2 is a block diagram showing a part of the control configuration of the image forming apparatus A in the first embodiment. In the figure, the symbol X indicates the width direction (depth direction), with the -X direction (negative X direction) being the front direction and the +X direction (positive X direction) being the rear direction. The symbol Y indicates the left-right direction Y perpendicular to the width direction X, with the -Y direction (negative Y direction) being the left direction and the +Y direction (positive Y direction) being the right direction. The symbol Z indicates the up-down direction, with the -Z direction (negative Z direction) being the down direction and the +Z direction (positive Z direction) being the up direction. These settings are the same in the following embodiments.

[0017] The image forming apparatus A is an electrophotographic image forming apparatus, and is an intermediate transfer type color multifunction machine capable of printing full color images. The image forming apparatus A has an image reading unit 1, an image forming unit 2, an intermediate transfer body 3, a secondary transfer unit 4, a fixing device 5, a sheet storage unit 6, a sheet roller group 7, a pre-registration sensor 70, and a sheet discharge unit 71 (see FIG. 1). The image forming apparatus A is provided with a sheet transport path S through which sheets are transported. In this embodiment, the image forming apparatus A uses toners of the colors yellow (Y), magenta (M), cyan (C), and black (K) for printing.

[0018] The image reading unit 1 reads an image from a document, and is provided on the upper part of the image forming apparatus A. The image reading unit 1 has a document reading device 10, a document placement table 11, and an automatic document processing device 12 (see FIG. 1).

[0019] The document reading device 10 irradiates a document with light and reads an image from the document based on the reflected light. The document reading device 10 includes, for example, a light source that irradiates the document with light, a lens, an image sensor, and a mirror that guides the reflected light from the document to the lens. The reflected light from the document that is incident on the image sensor via the lens is photoelectrically converted by the image sensor to generate image data.

[0020] The document placement table 11 is a portion on which a document is placed by a user, and is provided above the document reading device 10. The document placement table 11 is made of transparent glass. The automatic document processing device 12 is provided above the document placement table 11, and automatically and continuously transports documents inserted by a user to the document reading device 10. An image of the document is read by the document reading device 10 while the document is placed on the document placement table 11 or while the document is transported to the document reading device 10 by the automatic document processing device 12.

[0021] The image forming unit 2 forms a toner image based on image data, and includes an exposure device 20, a developing device 21, an image carrier 22, a charger 23, and a cleaning unit 24 (see FIG. 1). The image data may be generated by the image reading unit 1, or may be supplied from an external device.

[0022] The exposure device 20 exposes the surface of the image carrier 22, which has been charged by the charger 23, to light corresponding to each color, thereby forming an electrostatic latent image corresponding to each color on the image carrier 22. The exposure device 20 incorporates a light source that emits a laser beam, a polygon mirror that scans and reflects the laser beam, and optical elements (e.g., lenses, mirrors, etc.) that guide the laser light of the reflected laser beam to the image carrier 22.

[0023] The developing device 21 forms a toner image by visualizing (making visible) the electrostatic latent image formed on the surface of each image carrier 22 with toner of each color (Y, M, C, K) supplied from the toner cartridge T. The developing device 21 causes the toner to fly to the image carrier 22, whereby the toner is supplied to the electrostatic latent image formed on the surface of the image carrier 22, and a toner image is formed on the surface of the image carrier 22.

[0024] The image carrier 22, on whose surface an electrostatic latent image is formed, is rotated in a predetermined direction by the driving of a main motor (not shown). By the rotation of the image carrier 22, the toner image visualized on the image carrier 22 is transported to the intermediate transfer body 3.

[0025] The charger 23 charges the surface of the image carrier 22 uniformly to a predetermined potential.

[0026] The cleaning unit 24 removes and collects toner remaining on the surface of the image carrier 22 after development and image transfer.

[0027] The intermediate transfer body 3 is disposed above the image carrier 22, and the toner images of each color formed on the surface of the image carrier 22 are temporarily transferred onto the intermediate transfer body 3. The intermediate transfer body 3 has an intermediate transfer belt 30, a driving roller 31, a driven roller 32, and a primary transfer roller 33 (see FIG. 1).

[0028] The intermediate transfer belt 30 is an endless belt that rotates in a predetermined direction, and is suspended between a drive roller 31 and a driven roller 32. The outer surface of the intermediate transfer belt 30 is in contact with the image carrier 22. The toner images of each color visualized on the image carrier 22 are transferred in order onto the intermediate transfer belt 30 in a superimposed manner. The toner images transferred onto the intermediate transfer belt 30 are transported to the secondary transfer unit 4 by the rotation of the intermediate transfer belt 30. The intermediate transfer belt 30 is formed of, for example, a film having a thickness of about 100 μm to 150 μm.

[0029] The driving roller 31 is a roller that is rotated in a predetermined direction by driving a belt motor (not shown), and is provided on the right end side of the intermediate transfer body 3. The intermediate transfer belt 30 is rotated by the rotation of the driving roller 31.

[0030] The driven roller 32 is a roller that is rotatably provided along the intermediate transfer belt 30. The driven roller 32 is rotated in accordance with the rotation of the intermediate transfer belt 30.

[0031] The primary transfer rollers 33 are arranged in a row so as to correspond to the image carriers 22 via the intermediate transfer belt 30. Hereinafter, the transfer of the toner images of each color formed on the image carriers 22 onto the intermediate transfer belt 30 will be referred to as "primary transfer."

[0032] The secondary transfer unit 4 transfers the toner images of each color, which have been primarily transferred onto the intermediate transfer belt 30, onto a sheet. The secondary transfer unit 4 has a secondary transfer roller 40 provided at a transfer position where the sheet and the intermediate transfer belt 30 face each other. Hereinafter, the transfer of the toner images of each color, which have been transferred onto the intermediate transfer belt 30, onto a sheet will be referred to as "secondary transfer."

[0033] The fixing device 5 fixes the toner image onto the sheet by heating and melting the toner image that has been secondarily transferred onto the sheet and fixing it onto the sheet, and is provided upstream of the secondary transfer section 4 on the sheet transport path S.

[0034] The sheet storage unit 6 is disposed at the bottom of the image forming apparatus A, and has a sheet cassette 60 that stores sheets to be used for image formation. In this embodiment, the sheet cassette 60 corresponds to the "storage means" recited in the claims.

[0035] The sheet roller group 7 includes a pickup roller 7a, a supply roller 7b, a separation roller 7c, transport rollers 7d to 7f, and a registration roller 7g.

[0036] The pickup roller 7a pulls out the top sheet of the stack of sheets in the sheet cassette 60. The supply roller 7b sends the sheet out to the sheet transport path S. The separation roller 7c separates the sheets that have been pulled out in a stacked state one by one. The supply roller 7b rotates by receiving a driving force from a supply motor 90 (see FIG. 2), and the pickup roller 7a and separation roller 7c rotate following the rotation of the supply roller 7b. In this embodiment, the pickup roller 7a, supply roller 7b, and separation roller 7c constitute the "supply means" recited in the claims.

[0037] The conveying rollers 7d to 7f convey the sheet along the sheet conveying path S. The registration roller 7g temporarily stops the sheet conveyed from the sheet storage unit 6 and aligns the leading edge of the sheet. The conveying rollers 7d to 7f and the registration roller 7g rotate by receiving a driving force from a conveying motor 91 (see FIG. 2).

[0038] The pre-registration sensor 70 detects a sheet and is disposed upstream of the registration rollers 7g in the sheet transport path S (see FIG. 1). In this embodiment, the pre-registration sensor 70 corresponds to a "sheet detection unit" in the claims.

[0039] The sheet discharge section 71 is provided on the upper part of the image forming apparatus A, and is used to load and pull out printed sheets face down.

[0040] In addition to the above configuration, the image forming apparatus A is provided with a control unit 8 that controls each of the above-described components in response to an input operation by a user. The control unit 8 corresponds to the "control means" recited in the claims. The configuration of the control unit 8 will be described later.

[0041] The image forming apparatus A as described above prints on a sheet as follows. First, the image forming unit 2 forms a toner image based on image data generated by the image reading unit 1 or supplied from an external device. This toner image is primarily transferred onto the intermediate transfer belt 30 of the intermediate transfer body 3. During this time, the sheet is pulled out of the sheet cassette 60 by the pickup roller 7a, conveyed to the registration roller 7g by the conveyance roller 7d, and conveyed to the secondary transfer unit 4 by the registration roller 7g. Next, the secondary transfer unit 4 secondarily transfers the toner image primarily transferred onto the intermediate transfer belt 30 onto the sheet. The fixing device 5 fixes the toner image secondarily transferred onto the sheet. After that, the sheet is conveyed by the conveyance roller 7d and discharged onto the sheet discharge unit 71, completing the printing on the sheet.

[0042] The sheet may be manually fed from a manual feed tray 61 to the sheet conveying path S.

[0043] -Control Unit- Incidentally, when the sheets are pulled out from the sheet cassette 60 by the pickup roller 7a, the so-called "sheet dragging" may occur, in which the sheets are pulled out in a state where multiple sheets are overlapped. Of the multiple sheets that are dragged, the topmost sheet is sent to the sheet conveying path S by the separation roller 7c and the supply roller 7b, but the remaining sheets remain in a state where they are protruding from the pickup roller 7a. When such sheet dragging occurs, the interval between the sheets becomes narrower than when sheet dragging does not occur, and the probability of sheet jamming on the sheet conveying path S increases.

[0044] Therefore, in order to efficiently reduce the probability of sheet jamming, the control unit 8 judges whether or not the sheet has been fed early, and when it judges that the sheet has been fed early, waits until a predetermined extended standby time that is longer than a predetermined normal standby time has elapsed, and then causes the supply roller 7b to supply the succeeding sheet. The configuration and processing of the control unit 8 will be described in detail below.

[0045] <Control Unit Configuration> The control unit 8 has a processing unit 80, a storage unit 81, an input unit 82, and an output unit 83 (see FIG. 2), which are connected to each other by a bus line (not shown). The input unit 82 is communicatively connected to the pre-registration sensor 70, and the output unit 83 is communicatively connected to a supply motor 90 and a transport motor 91.

[0046] The processing unit 80 includes a CPU (Central Processing Unit), etc. The processing unit 80 has a sheet early feed determination unit 800 that determines whether or not a sheet early feed has occurred (see FIG. 2).

[0047] In this embodiment, the early feed determination unit 800 determines whether or not the early feed of the sheet has occurred based on the "sheet feed time" from when the processing unit 80 rotates the supply roller 7b via the supply motor 90 to start supplying the sheet to the supply roller 7b until the pre-registration sensor 70 detects the sheet. When the early feed of the sheet has occurred, the timing at which the sheet protruding from the pickup roller 7a is detected by the pre-registration sensor 70 tends to be earlier than when the early feed of the sheet has not occurred. For this reason, the early feed determination unit 800 determines that the early feed of the sheet has not occurred when the sheet feed time is equal to or greater than a later-described supply time reference value 811, and determines that the early feed of the sheet has occurred when the sheet feed time is less than the supply time reference value 811.

[0048] The storage unit 81 includes a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory). A control program 810 and a supply time reference value 811 are stored in the storage unit 81. The control program 810 is stored in the ROM of the storage unit 81. Under the control of the processing unit 80, the control program 810 stored in the ROM is read out and loaded onto the RAM, thereby executing the control program 810. Note that the control program 810 is not limited to the above, and may be read from a recording medium such as a HDD, or downloaded from a network such as a LAN (Local Area Network).

[0049] The supply time reference value 811 is a value that is a reference for a sheet supply time, and is a value that is referred to by the early feed determination unit 800. In this embodiment, the supply time reference value 811 is set as a fixed value.

[0050] <Processing mode> In this embodiment, the control unit 8 has a normal mode in which the supply roller 7b waits until a predetermined normal standby time has elapsed and then starts supplying the succeeding sheet, and a supply delay mode in which the supply roller 7b waits until a predetermined extended standby time longer than the normal standby time has elapsed and then starts supplying the succeeding sheet. The control unit 8 selectively executes the normal mode or the supply delay mode for each predetermined number of sheets, or for each sheet in this embodiment, based on whether or not sheet advancement has occurred. Specifically, it is as follows.

[0051] When the early feed determination unit 800 of the processing unit 80 determines that early feed of a sheet has not occurred, the processing unit 80 of the control unit 8 waits until a predetermined normal standby time has elapsed, and then executes a normal mode in which the supply roller 7b is rotated via the supply motor 90 to start supplying the succeeding sheet to the supply roller 7b. On the other hand, when the early feed determination unit 800 determines that early feed of a sheet has occurred, the processing unit 80 waits until a predetermined extended standby time longer than the normal standby time has elapsed, and then executes a supply delay mode in which the supply roller 7b is rotated via the supply motor 90 to start supplying the succeeding sheet to the supply roller 7b. As a result, the timing at which the supply of the succeeding sheet is started is delayed according to the occurrence status of early feed of a sheet, and the interval between the sheets narrowed by early feed of a sheet is appropriately widened, so that the occurrence probability of a sheet jam can be efficiently suppressed.

[0052] In this embodiment, the processing section 80 executes the supply delay mode after starting the rotation of the registration rollers 7g via the conveying motor 91. As a result, after the preceding sheet is conveyed by the registration rollers 7g, the supply rollers 7b start supplying the succeeding sheet, so that even if the preceding sheet is temporarily stopped by the registration rollers 7g, the interval between the sheets can be reliably widened.

[0053] <Processing Procedure> Next, the processing procedure of the control unit 8 in the above processing mode will be described.

[0054] Fig. 3 is a flowchart showing a part of the processing procedure by the control unit 8 in the embodiment 1. The series of processes shown in Fig. 3 are repeated according to the number of sheets to be processed. For the sake of convenience, the step of rotating the registration roller 7g is omitted in the figure.

[0055] First, in step S1, the processing unit 80 of the control unit 8 rotates the supply roller 7b via the supply motor 90 to cause the supply roller 7b to start supplying a sheet. Here, the processing unit 80 stores in the memory unit 81, as a sheet supply time, the supply start time at which the supply roller 7b starts supplying the sheet.

[0056] Next, in step S2, the processing unit 80 acquires from the pre-registration sensor 70 the sheet detection time at which the pre-registration sensor 70 detects the sheet.

[0057] Next, in step S3, the processing section 80 calculates the sheet supply time from the difference between the sheet detection time and the sheet supply time.

[0058] In step S4, the early feed determination unit 800 of the processing unit 80 determines whether the calculated sheet supply time is less than the supply time reference value 811. If the sheet supply time is equal to or greater than the supply time reference value 811, the processing unit 80 proceeds to the normal mode in step S5, waits until the normal standby time has elapsed, and then causes the supply roller 7b to start supplying the succeeding sheet (step S1). On the other hand, if the sheet supply time is less than the supply time reference value 811, the processing unit 80 proceeds to the supply delay mode in step S6, waits until the extended standby time has elapsed, and then causes the supply roller 7b to start supplying the succeeding sheet (step S1).

[0059] (Example of embodiment 1) An example of the above-mentioned embodiment 1 will now be described.

[0060] 4 is a table showing a part of the processing contents by the control unit 8 in one example of the embodiment 1. In the figure, the arrows show the correspondence between the sheet supply time and the time that the processing unit 80 waits until the start of supplying the subsequent sheet based on that time.

[0061] 4, the item "No." is a column showing the sheet number, the item "Sheet supply time" is a column showing the sheet supply time corresponding to each sheet, the item "Sheet interval" is a column showing the distance between the leading edge of each sheet and the trailing edge of the preceding sheet preceding each sheet, the item "Supply start waiting time" is a column showing the time that the processing unit 80 of the control unit 8 waits until the start of supplying each sheet, and the item "CPM" is a column showing CPM (Copies Per Minute) showing the number of sheets processed per minute. In this embodiment, the supply time reference value 811 is set to 550 ms, the normal waiting time is set to 858 ms, and the extended waiting time is set to 919 ms.

[0062] As shown in FIG. 4, for sheet No. 2, the feeding time is equal to or greater than the supply time reference value 811, so the early feed determination unit 800 of the processing unit 80 determines that sheet early feed has not occurred. Therefore, the processing unit 80 executes the normal mode. The processing unit 80 waits until the normal standby time has elapsed, and then causes the supply roller 7b to start feeding the subsequent sheet, i.e., sheet No. 3. Next, for sheet No. 3, the feeding time is less than the supply time reference value 811, so the early feed determination unit 800 determines that sheet early feed has occurred. Therefore, the processing unit 80 executes the supply delay mode. The processing unit 80 waits until the extended standby time has elapsed, and then causes the supply roller 7b to start feeding the subsequent sheet, i.e., sheet No. 4.

[0063] In this way, by delaying the timing at which the supply of the succeeding sheet is started depending on the occurrence status of the sheet early feed, it is possible to appropriately widen the interval between sheets narrowed by the sheet early feed as shown in the item "sheet interval." In addition, since the normal mode or the delayed feed mode is selectively executed for each predetermined number of sheets depending on whether the sheet early feed has occurred or not, it is possible to maintain the processing efficiency as shown in the item "CPM."

[0064] The first embodiment is not limited to the control of sheet supply from the sheet cassette 60 of the sheet storage unit 6, but can also be applied to the control of sheet supply from either the manual feed tray 61 or the automatic document processing device 12.

[0065] Furthermore, the supply time reference value 811 may be a variable value that varies under certain conditions.

[0066] Moreover, the normal standby time and the extended standby time may be fixed values ​​set in advance, or may be variable values ​​that vary under predetermined conditions.

[0067] (Embodiment 2) Hereinafter, the second embodiment will be described only with respect to the points different from the first embodiment.

[0068] Fig. 5 is a schematic diagram showing a state in which a plurality of sheets are stacked in the sheet cassette 60 with the burrs of each sheet facing upward. Fig. 6 is a schematic diagram showing a state in which a plurality of sheets are stacked in the sheet cassette 60 with the burrs of each sheet facing downward.

[0069] However, when the supply delay mode is executed a predetermined number of times in succession, the following events may be expected. Generally, since a sheet is cut, it has a burr at the end as shown in FIG. 5 and FIG. 6. As shown in FIG. 5, when a plurality of sheets are stacked in the sheet cassette 60 so that the burr of each sheet on the opposite side of the sheet pull-out direction faces upward, when a top sheet is pulled out of the sheet cassette 60, the burr of the sheet is unlikely to interfere with the sheet in the lower layer, and sheet dragging is unlikely to occur. On the other hand, as shown in FIG. 6, when a plurality of sheets are stacked in the sheet cassette 60 so that the burr of each sheet on the opposite side of the sheet pull-out direction faces downward, when a top sheet is pulled out of the sheet cassette 60, the burr of the sheet interferes with the sheet in the lower layer, and sheet dragging is likely to occur. When the supply delay mode is executed a predetermined number of times in succession, that is, when the dragging determination unit 800 determines that a sheet dragging has occurred a predetermined number of times in succession, an event may be expected in which a plurality of sheets are in a state as shown in FIG. 6. Therefore, the control unit 8 in the second embodiment has the following technical features in order to reduce the probability of occurrence of the accompanied sheet feeding.

[0070] FIG. 7 is a block diagram showing a part of the control configuration of the image forming apparatus A according to the second embodiment.

[0071] In the second embodiment, the control unit 8 further includes a notification unit 84 capable of notifying the user of information (see FIG. 7). The processing unit 80 further includes a count unit 801 that counts the number of times the supply delay mode is executed consecutively.

[0072] When the count value of the count unit 801 is equal to or greater than a predetermined value, that is, when the supply delay mode in which the supply roller 7b is made to supply the succeeding sheet after waiting until the extended waiting time has elapsed has been executed a predetermined number of times in succession, the processing unit 80 of the control unit 8 issues an alert to the user through the notification unit 84. Specifically, the notification unit 84 notifies the user to invert the sheet surface by using voice output or display of a text image or the like on a display unit (not shown). This makes it possible to reduce the frequency of occurrence of the sheet being conveyed together.

[0073] (Embodiment 3) Hereinafter, the third embodiment will be described only with respect to the points different from the first embodiment.

[0074] Fig. 8 is a block diagram showing a part of the control configuration of the image forming apparatus A in the third embodiment. Fig. 9 is a diagram showing an example of a correction table 812 in the third embodiment.

[0075] In the third embodiment, the image forming apparatus A further includes a size discrimination means 9a for discriminating the size of the sheet, and a temperature and humidity measuring means 9b for measuring the temperature and humidity around the sheet cassette 60 corresponding to the storage means (see FIG. 8). The size discrimination means 9a may be, for example, a photoelectric sensor such as a reflective optical sensor. The temperature and humidity measuring means 9b may be, for example, a temperature and humidity sensor.

[0076] In the third embodiment, the storage unit 81 of the control unit 8 stores a correction table 812, which is a calculation table to be referred to for correcting the normal standby time and the extended standby time (see FIGS. 8 and 9).

[0077] The correction table 812 associates predetermined correction conditions with the correction amounts corresponding to each correction condition. The item "processing mode" of the correction table 812 is a column indicating the conditions of the processing mode of the control unit 8, the item "size" is a column indicating the conditions of the sheet size, the item "temperature and humidity" is a column indicating the conditions of the temperature and humidity around the sheet cassette 60, and the item "correction amount (ms)" is a column indicating the correction amount of the normal standby time or the extended standby time according to the processing mode when each condition indicated by the items "processing mode", "size" and "temperature and humidity" is satisfied (see FIG. 9). In the item "size", "LT" indicates letter size. In the item "temperature and humidity", "N" indicates the case where the temperature and humidity around the sheet cassette 60 is less than a predetermined threshold, and "H" indicates the case where the temperature and humidity around the sheet cassette 60 is equal to or greater than a predetermined threshold.

[0078] The processing unit 80 refers to the correction table 812 and changes the normal standby time and the extended standby time based on the size of the sheet determined by the size determination unit 9a. The processing unit 80 also refers to the correction table 812 and changes the normal standby time and the extended standby time based on the measurement result of the temperature and humidity measurement unit 9b. For example, if the size of the sheet is determined to be LT (letter size) by the size determination unit 9a, the temperature and humidity around the sheet cassette 60 measured by the temperature and humidity measurement unit 9b are equal to or higher than a predetermined threshold, and the processing unit 80 is executing the normal mode, the normal standby time is corrected by +α (ms) (see the third column from the top and the fourth column from the left in FIG. 9). Similarly, if the size of the sheet is determined to be other than LT (letter size) by the size determination unit 9a, the temperature and humidity around the sheet cassette 60 measured by the temperature and humidity measurement unit 9b are equal to or higher than a predetermined threshold, and the processing unit 80 is executing the supply delay mode, the normal standby time is corrected by +β+δ (ms) (see the ninth column from the top and the fourth column from the left in FIG. 9).

[0079] As described above, the processing unit 80 changes the normal standby time and the extended standby time based on the size of the sheets, so that the interval between the sheets can be appropriately adjusted according to the size of the sheets.

[0080] Furthermore, as described above, by the processing unit 80 changing the normal standby time and the extended standby time based on the measurement results of the temperature and humidity measuring means 9b, i.e., the temperature and humidity around the sheet cassette 60, even if an increase in temperature and humidity makes the sheets more likely to stick together and cause sheet dragging, the spacing between the sheets can be appropriately widened, thereby efficiently reducing the probability of sheet jams.

[0081] The correction table 812 may be composed of separate correction tables that correlate the sheet size condition and the temperature and humidity condition around the sheet cassette 60 with the correction amount.

[0082] The above-mentioned embodiments and examples are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention is not interpreted solely by the above-mentioned embodiments and examples, but is defined based on the claims. In addition, all modifications within the meaning and scope of the claims are included. [Explanation of symbols]

[0083] A Image forming device 1 Image reading unit 2 Image forming section 3 Intermediate transfer body 4 Secondary transfer section 5 Fixing device 6 Seat storage area 7a Pickup roller 7b Supply roller 7c separation roller 7g Registration roller 70 Pre-resist sensor 8. Control Unit 8. Control Unit 80 Processing section 800 escort judgement department 801 Counting Department 81 Storage section 810 Control Program 811 Supply time reference value 812 Correction Table 82 Input section 83 Output section 84 Notification Department 9a Size discrimination means 9b Temperature and humidity measuring means 90 Supply motor 91 Transport motor

Claims

1. A storage means for storing the sheet; a supply means for supplying the sheets one by one from the storage means to a sheet transport path; a sheet detection means arranged on the sheet transport path and configured to detect the passage of the sheet; A control means for controlling the supply means; An image forming apparatus including a notification unit capable of notifying a user of information, The control means When a sheet supply time from when the supply means starts supplying the sheet to when the sheet detection means detects the sheet is less than a predetermined reference value, determining that a sheet has been fed, and waiting until a predetermined extended standby time that is longer than a predetermined normal standby time has elapsed, and then causing the supplying means to supply a subsequent sheet; The notification unit waits until the extended waiting time has elapsed, and when a supply delay that causes the supply means to supply the subsequent sheet has been executed a predetermined number of times in succession, the notification unit issues a notification to prompt a user to turn over the sheet surface. An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, a registration roller disposed on the sheet conveying path, The supply means has a supply roller that rotates by receiving a driving force, the sheet detection means is a pre-registration sensor disposed upstream of the sheet conveying path with respect to the registration rollers, the sheet supply time is a time from when the supply roller starts to rotate to when the pre-registration sensor detects the sheet, The image forming apparatus according to claim 1, wherein the control means waits until the extended waiting time has elapsed after the registration rollers start rotating, and then causes the supply means to supply a subsequent sheet.

3. 3. The image forming apparatus according to claim 1, The apparatus further includes a size determining means for determining a size of the sheet, The control means an image forming apparatus that changes the normal standby time and the extended standby time based on the size of the sheet determined by the size determination means;

4. 4. The image forming apparatus according to claim 1, A temperature and humidity measuring means for measuring the temperature and humidity around the storage means is further provided, The control means an image forming apparatus that changes the normal standby time and the extended standby time based on a measurement result of the temperature and humidity measuring means;

5. A method for controlling a supplying means for supplying sheets one by one to a sheet conveying path, comprising the steps of: When the time from when the supplying means starts supplying the sheet to when the sheet passes a predetermined position on the sheet transport path is less than a predetermined reference value, determining that a sheet has been fed, and waiting until a predetermined extended standby time that is longer than a predetermined normal standby time has elapsed, and then causing the supplying means to supply a subsequent sheet; When the supply delay for causing the supply means to supply the subsequent sheet is executed a predetermined number of times in succession after waiting until the extended waiting time has elapsed, a notification is given to prompt a user to turn over the sheet surface. A method for controlling a supply means, comprising:

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