JP2013076839A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an occurrence of a situation in which residual toner on an intermediate transfer belt is required to be cleaned while maintaining performance for cleaning the residual toner thereon, to reduce cleaning time and to enhance productivity of image formation by an image forming device.SOLUTION: In a case where the number of recording media required for remaining image formation in an image formation job is determined to be larger than the number of storage recording sheets to be used in the image formation job of a sheet feeding cassette by a first determining section 106, and the number of recording media required for the remaining image formation is determined to be smaller than the number of storage recording sheets of another applicable sheet feeding cassette by a second determining section 107, a sheet feeding mechanism switching section 108 switches the sheet feeding cassette used to the another applicable sheet feeding cassette, and, after switching-over thereto, a cleaning controller 105 causes a cleaning section 22 to perform cleaning.

Description

  The present invention relates to an image forming apparatus, and more particularly to a technique for cleaning an intermediate transfer belt on which a toner image is formed.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an intermediate transfer method in which a toner image is formed on an intermediate transfer member such as an intermediate transfer belt and then the toner image is transferred to a recording paper, the time required for image formation on the intermediate transfer belt In order to reduce the printing time by reducing the influence on productivity, before the recording paper is transported from the intermediate transfer belt to the position where the toner image is transferred, the image forming unit transfers the recording paper onto the intermediate transfer belt. There is known a method of starting the image formation in advance.

  When this method is adopted, the recording paper may be transferred when the toner image is transferred from the intermediate transfer belt due to a change in the paper feeding cassette or slippage of a conveyance roller that transports the recording paper from the paper feeding cassette to the toner image transfer. If the toner image transfer position (secondary transfer position) cannot be reached, the toner image that could not be transferred onto the recording paper due to this conveyance delay remains on the intermediate transfer belt. For this reason, Patent Document 1 below proposes a cleaning technique for removing the residual toner from the intermediate transfer belt.

  Further, a technique has been proposed in which residual toner is transferred from an intermediate transfer belt to a secondary transfer member (for example, a secondary transfer roller) to reduce the amount of toner that must be removed from the intermediate transfer belt during cleaning. In the image forming apparatus described in Patent Document 2 below, after transferring the residual toner to the secondary transfer member in this way, the secondary transfer roller is used when the toner image is transferred from the intermediate transfer belt to the recording paper next time. A toner adhesion prevention mechanism is further provided to prevent the residual toner transferred to the recording paper from adhering to the recording paper.

JP 2006-113217 A JP 2010-204521 A

  In the image forming apparatus of the type in which the image formation precedes the conveyance of the recording paper as described above, if the conveyance delay of the recording paper occurs during the image formation, the time for the cleaning operation is required in addition to the printing time. There is a concern that productivity (printing efficiency on recording paper) may be lowered by the image forming apparatus. In order to suppress the decrease in productivity of the image forming apparatus, it is required to reduce the cleaning operation time by preventing the occurrence of a situation that requires cleaning.

  In the case of the technique described in Patent Document 1, the number of times the intermediate transfer belt is passed through the cleaning mechanism can be set to an appropriate value according to the developer ratio of the toner image transferred onto the intermediate transfer belt, but cleaning is required. It is not possible to prevent the occurrence of the situation. Further, in Patent Document 2, when using the toner adhesion prevention mechanism and used paper as a recording paper (so-called backing paper, one side of which is printed and the other side is blank paper) Although it is described that the toner adhesion preventing process by the toner adhesion preventing mechanism is refrained, the described technique does not prevent the occurrence of a situation that requires cleaning.

  The present invention has been made in order to solve the above-described problem, and while maintaining the performance of cleaning the residual toner on the intermediate transfer belt, the occurrence of a situation that requires cleaning is prevented and the cleaning time is increased. It is an object of the present invention to reduce and increase the productivity of image formation by an image forming apparatus.

The invention according to claim 1 of the present invention includes a plurality of paper feed mechanisms for storing recording media;
A stored number detection unit for detecting the number of recording media stored in each of the paper feed mechanisms;
An intermediate transfer belt stretched between a plurality of rollers so as to be able to run endlessly;
An image forming unit for forming a toner image on the intermediate transfer belt;
A transfer unit for transferring a toner image formed on the intermediate transfer belt to a recording medium passing between the intermediate transfer belt;
A transport unit that transports a recording medium stored in the paper feeding mechanism to a transfer position of the toner image by the transfer unit;
A cleaning unit that performs a cleaning operation to remove residual toner from the intermediate transfer belt;
A job accepting unit that accepts a plurality of image forming jobs specifying the paper feeding mechanism in which a recording medium to be conveyed to the conveying unit is stored;
During execution of an image forming job accepted by the job accepting unit, a delay detecting unit detects whether the conveyance of the recording medium to the transfer position by the conveying unit is delayed with respect to the image transfer timing by the transfer unit. When,
A cleaning control unit for causing the cleaning unit to perform the cleaning operation;
When the delay detection unit detects the conveyance delay of the recording medium, the number of recording media necessary for the remaining image formation in the image forming job currently being executed is used for the execution of the image forming job. A first determination unit that determines whether or not the sheet feeding mechanism is greater than the stored number of sheets detected by the stored number of sheets detection unit;
When the first determination unit determines that the number of recording media required for the remaining image formation is larger than the storage number detected by the storage number detection unit, it is necessary for the remaining image formation. The number of recording media is a paper feed mechanism different from the paper feed mechanism used for the image forming job being executed, and the stored number detection unit for the paper feed mechanism applicable to the image forming job A second determination unit that determines whether the number of stored sheets is equal to or less than the number of stored sheets detected by
When it is determined by the second determination unit that the number of recording media necessary for the remaining image formation is equal to or less than the number of stored sheets by the stored number detection unit detected for the applicable sheet feeding mechanism. A paper feed mechanism switching unit that switches the paper feed mechanism used for the image forming job being executed to the applicable paper feed mechanism;
The cleaning control unit is an image forming apparatus that causes the cleaning unit to perform the cleaning operation after the sheet feeding mechanism is switched by the sheet feeding mechanism switching unit.

  If the transfer of the recording medium to the transfer position of the toner image by the intermediate transfer belt and the transfer unit is delayed during the image forming job, the image formation is interrupted at this point and the intermediate immediately Even after the transfer belt has been cleaned, if the paper feed mechanism is switched later, the paper feed after the switching will occur due to the change in the recording medium transport path accompanying this switching, the paper feed start timing from the paper feed mechanism after the switching, etc. The conveyance of the recording medium from the paper mechanism may be delayed with respect to the toner image transfer timing started prior to the conveyance, and in this case, the intermediate transfer belt needs to be cleaned again.

  In the present invention, when the conveyance of the recording medium to the transfer position of the toner image is delayed with respect to the transfer timing of the toner image, the number of recording media necessary for the remaining image formation in the image forming job being executed is More than the number of sheets stored in the sheet feeding mechanism used for image formation in this image forming job, it is necessary to switch to recording medium supply from another sheet feeding mechanism due to a shortage of recording media later. In some cases, if there is another paper feeding mechanism that stores a larger number of recording media than the number of recording media required for the remaining image formation, the paper feeding mechanism used for the image forming job being executed is changed. After the switching to the other paper feeding mechanism, the cleaning operation for the intermediate transfer belt by the cleaning unit is performed.

  For this reason, in the present invention, the conveyance of the recording medium from the switched another sheet feeding mechanism is started after the cleaning operation, and while the operation time for the cleaning has elapsed, Since the processing and operation necessary for changing the recording medium conveyance path by switching can be completed, even if the sheet feeding from the sheet feeding mechanism is started immediately after the switching, the recording medium conveyance is delayed with respect to the toner image transfer timing. The possibility is reduced. Thereby, the number of cleaning operations of the intermediate transfer belt when it is necessary to switch the sheet feeding mechanism can be reduced. Therefore, the present invention prevents the occurrence of a situation that requires cleaning without particularly degrading the performance of cleaning the residual toner on the intermediate transfer belt, thereby reducing the cleaning time, and the image formed by the image forming apparatus. The productivity of formation can be increased.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a type storage unit that stores the type of the recording medium stored in the paper feeding mechanism for each of the paper feeding mechanisms. In addition,
The second determination unit stores in the type storage unit the same recording medium type as the recording medium type stored in the type storage unit for the paper feed mechanism used in the image forming job being executed. The other paper feeding mechanism is the applicable paper feeding mechanism.

  According to this invention, the second determination unit is provided on condition that the same recording medium type as that stored in the paper feeding mechanism used for the image forming job being executed is stored. In order to determine that the sheet feeding mechanism is the applicable sheet feeding mechanism, even if the sheet feeding mechanism switching unit switches the sheet feeding mechanism so far to the other sheet feeding mechanism, the recording medium used so far It is possible to perform image formation on the same recording medium as that for image formation and maintain the same image formation result.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the second determination unit is housed in the paper feed mechanism used in the image forming job being executed. The type of the recording medium having an image forming area having an area equal to or larger than the image forming area of the recorded recording medium is different from the paper feeding mechanism stored in the type storage unit, and the same recording medium type is This is determined as another sheet feeding mechanism stored in the type storage unit.

  According to the present invention, the second determination unit has an image forming area having an area larger than the image forming area of the recording medium stored in the paper feeding mechanism used in the image forming job being executed. Since the paper feed mechanism in which the recording medium is stored is determined as the applicable paper feed mechanism, even if the paper feed mechanism switching unit switches to the other paper feed mechanism, the recording medium used so far The image formation can be performed with the same contents even with other recording media without performing processing such as reduction.

  According to the present invention, while maintaining the performance of cleaning the residual toner on the intermediate transfer belt, it is possible to prevent the occurrence of a situation where cleaning is necessary and reduce the cleaning time. Productivity can be increased.

1 is a front sectional view showing a structure of an image forming apparatus according to an embodiment of the present invention. 2 is a functional block diagram schematically showing a main internal configuration of the image forming apparatus. FIG. (A) (B) is a figure which shows the outline of the internal mechanism of a paper feed cassette. 6 is a flowchart illustrating execution control of an image forming job by the image forming apparatus.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view showing the structure of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is a multifunction machine having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes an apparatus main body 11 including an image forming unit 12, a fixing device 13, a paper feeding unit 14, a paper discharging unit 15, a document feeding unit 6, a document reading unit 5, and the like.

  The apparatus main body 11 includes a lower main body 111, an upper main body 112 disposed so as to face the lower main body 111, and a connecting portion 113 provided between the upper main body 112 and the lower main body 111. The connecting portion 113 is a structure for connecting the paper discharge portion 15 between the lower main body 111 and the upper main body 112 to each other. In FIG. And is L-shaped in a plan view. The upper body 112 is supported on the upper end portion of the connecting portion 113. The upper body 112 is provided with a document reading unit 5 and a document feeding unit 6.

  The document reading unit 5 includes a contact glass (document table) 161 mounted on the upper surface opening of the upper main body 112 and an openable / closable document presser for pressing the document placed on the contact glass 161. A cover 162 and a reading mechanism 163 that reads an image of a document placed on the contact glass 161 are provided. The reading mechanism 163 optically reads an image of a document using an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and generates image data.

  The document feeding unit 6 includes a document placing table 61 on which a document is placed, a document discharge unit 66 from which an image-read document is discharged, and a document transport mechanism 65. The document transport mechanism 65 includes a paper feed roller, a transport roller, and a paper reversing mechanism (not shown). The document transport mechanism 65 drives the paper feed roller and the transport roller to feed the document placed on the document placing table 61 one by one to a position facing the document reading slit 53, and passes the document reading slit 53 through the document reading slit 53. Then, after reading by the reading mechanism 163 is possible, the document is discharged to the document discharge unit 66. Further, the document transport mechanism 65 causes the paper reversing mechanism to reverse the document and to transport it again to a position facing the document reading slit 53, so that images on both sides of the document are read through the document reading slit 53. 163 enables reading.

  Further, the document feeding unit 6 is provided so as to be rotatable with respect to the upper body 112 so that the front side thereof can move upward. By moving the front side of the document feeder 6 upward to open the upper surface of the contact glass 161 as a document table, the user places a read document, for example, a book in a spread state, on the upper surface of the contact glass 161. It can be done.

  The lower main body 111 includes an image forming unit 12, a fixing device 13, and a paper feeding unit 14. The upper body 112 is provided with a document reading unit 5. The paper feed unit 14 has paper feed cassettes 142, 143, and 144 that can be inserted into and removed from the apparatus main body 11. Each of the paper feed cassettes 142, 143, and 144 stores a sheet bundle in which recording sheets (an example of a recording medium) are stacked. In the present embodiment, three stages of paper feed cassettes 142, 143, and 144 are provided. However, the present invention is not limited to this, and the paper feed cassettes may be provided in other plural stages, for example, four or more stages.

  The image forming unit 12 performs an image forming operation for forming a toner image on the recording paper fed from the paper feeding unit 14. The image forming unit 12 is arranged in order from the upstream side to the downstream side in the traveling direction of the intermediate transfer belt 125, the magenta image forming unit 12M using magenta toner, and the cyan toner using cyan toner. Image forming unit 12C, yellow image forming unit 12Y using yellow toner, and black image forming unit 12B using black toner (hereinafter, each image forming unit is described without distinction. Each of which is referred to as an “image forming unit 120”, and an intermediate transfer belt 125 stretched between a plurality of rollers such as a driving roller 125a (secondary transfer opposing roller) so as to be capable of endless running in the sub-scanning direction in image formation The intermediate transfer belt 125 is a portion where the intermediate transfer belt 125 is stretched around the driving roller 125a. And a secondary transfer roller 210 abutting against the outer peripheral surface 25.

  Each image forming unit 120 includes a photosensitive drum 121, a developing device 122 that supplies toner to the photosensitive drum 121, a toner cartridge (not shown) that stores toner, a charging device 123, an exposure device 124, a primary device. A transfer roller 126 and a drum cleaning device 127 are integrally provided.

  The photosensitive drum 121 forms an electrostatic latent image and a toner image along the electrostatic latent image on the peripheral surface thereof. The developing device 122 supplies toner to the photosensitive drum 121. Each developing device 122 is appropriately supplied with toner from the toner cartridge.

  The charging device 123 is provided immediately below the photosensitive drum 121. The charging device 123 uniformly charges the peripheral surface of each photosensitive drum 121.

  The exposure device 124 is provided below the photosensitive drum 121 and further below the charging device 123. The exposure device 124 irradiates the peripheral surface of the charged photosensitive drum 121 with laser light corresponding to each color based on image data input from a computer or the like or image data acquired by the document reading unit 5, and each photosensitive member. An electrostatic latent image is formed on the peripheral surface of the drum 121. The exposure device 124 is a so-called laser exposure device, which is a laser light source that outputs a laser beam, a polygon mirror that reflects the laser beam toward the surface of the photosensitive drum 121, and a laser beam reflected by the polygon mirror. Optical components such as a lens and a mirror for guiding the drum 121 are provided.

  The developing device 122 supplies toner to the electrostatic latent image on the peripheral surface of the photoconductive drum 121 rotating in the direction of the arrow and stacks the toner, and the toner corresponding to the image data is formed on the peripheral surface of the photoconductive drum 121. Form an image.

  The intermediate transfer belt 125 is disposed above the photosensitive drums 121. The intermediate transfer belt 125 is stretched between the driving roller 125a on the left side in FIG. 1 and the driven roller 125b on the right side in FIG. It is in contact. The driven roller 125b is provided at a position facing the driving roller 125a and rotates following the endless running of the intermediate transfer belt 125. The intermediate transfer belt 125 is driven by a driving roller 125 a in a state where an image carrying surface on which a toner image is transferred is set on the outer peripheral surface thereof and in contact with the peripheral surface of the photosensitive drum 121. The intermediate transfer belt 125 travels endlessly between the driving roller 125a and the driven roller 125b while being synchronized with each photosensitive drum 121.

  A primary transfer roller 126 is provided at a position facing each photosensitive drum 121 with the intermediate transfer belt 125 interposed therebetween. A transfer bias is applied to the primary transfer roller 126 by a transfer bias applying mechanism (not shown), and the primary transfer roller 126 transfers the toner image formed on the outer peripheral surface of each photosensitive drum 121 to the intermediate transfer belt 125. Transfer to the surface.

  The drive roller 125a causes the intermediate transfer belt 125 to run endlessly by a rotational driving force applied from a drive motor (not shown) driven under the control of a control unit (not shown).

  The operation control unit 100 (FIG. 2) drives and controls the primary transfer roller 126 and the image forming unit 120 for each color, and the magenta image formed on the surface of the intermediate transfer belt 125 by the magenta image forming unit 12M. Transfer of the toner image, transfer of the cyan toner image formed by the cyan image forming unit 12C to the same position of the intermediate transfer belt 125, and then yellow image forming unit 12Y to the same position of the intermediate transfer belt 125 The transfer of the yellow toner image formed by the above-mentioned process and the transfer of the black toner image formed by the last black image forming unit 12B are performed so that the toner images of the respective colors overlap each other. An image is formed on the surface of the intermediate transfer belt 125 (intermediate transfer (primary transfer)).

  The secondary transfer roller (transfer unit) 210 is applied with a transfer bias by a transfer bias application mechanism (not shown). The secondary transfer roller 210 transfers the color toner image formed on the surface of the intermediate transfer belt 125 onto the recording paper conveyed from the paper supply unit 14. The secondary transfer roller 210 is provided in contact with the outer peripheral surface of the intermediate transfer belt 125 in the sheet conveyance path 190 where the intermediate transfer belt 125 is stretched around the drive roller 125a. The secondary transfer roller 210 forms a nip portion N where the toner image is secondarily transferred onto the recording paper, with the intermediate transfer belt 125 and the drive roller 125a. The recording sheet conveyed through the sheet conveying path 190 is pressed and sandwiched between the intermediate transfer belt 125 and the secondary transfer roller 210 at the nip portion N, where the toner image on the intermediate transfer belt 125 is secondarily transferred to the recording sheet. The

  Note that a registration roller 630 is disposed upstream of the nip portion N between the secondary transfer roller 210 and the driving roller 125a in the recording paper conveyance direction by the paper conveyance unit 411. The registration roller 630 performs recording in order to synchronize the toner image transfer timing from the intermediate transfer belt 125 by the secondary transfer roller 210 at the upper nip portion N and the timing at which the paper transport portion 411 transports the recording paper to the nip portion N. This is for waiting for the conveyance of the paper.

  A registration sensor 63 is disposed on the upstream side of the registration roller 630 in the recording paper conveyance direction by the paper conveyance unit 411.

  The drum cleaning device 127 is provided on the left side of each photoconductive drum 121 in FIG. 1, and removes residual toner on the peripheral surface of the photoconductive drum 121 for cleaning. The peripheral surface of the photosensitive drum 121 cleaned by the drum cleaning device 127 goes to the charging device 123 again for a new charging process.

  A sheet conveyance path 190 extending in the vertical direction is formed at the left position in FIG. 1 with respect to the image forming unit 12. A conveyance roller 192 is provided at an appropriate position on the sheet conveyance path 190. The conveyance roller 192 conveys the recording paper fed from the paper supply unit 14 toward the nip N and the fixing device 13. A transport mechanism including the transport rollers 192 disposed at the appropriate position is an example of a transport unit.

  The fixing device 13 includes a heating roller 132 provided with an energization heating element as a heating source therein, and a pressure roller 134 disposed to face the heating roller 132. The fixing device 13 applies heat from the heating roller 132 to the toner image on the recording paper transferred by the image forming unit 12 while the recording paper passes through the fixing nip portion between the heating roller 132 and the pressure roller 134. To give a fixing process. The recording sheet on which the color image has been formed after the fixing process is completed is discharged toward a discharge tray 151 provided on the top of the lower main body 111 through a discharge conveyance path 194 extending from the upper part of the fixing device 13. The

  A cleaning unit 22 is provided at a position facing the outer peripheral surface of the intermediate transfer belt 125 stretched around the driven roller 125b. The cleaning unit 22 removes residual toner remaining on the surface of the intermediate transfer belt 125 after the toner image is transferred to the recording paper. The cleaning unit 22 includes, for example, a cleaning roller 24, a cleaning blade 25, and drive sources (not shown) such as a motor and a reduction gear.

  The cleaning roller 24 is a cleaning member that contacts the surface of the intermediate transfer belt 125 and removes the residual toner. The cleaning roller 24 is made of, for example, foamed melamine resin, and is disposed to face the driven roller 125b in a state where the surface of the intermediate transfer belt 125 is in contact. Further, the cleaning roller 24 is rotationally driven by the drive source (not shown) so that the rotation direction of the circumferential surface of the cleaning roller 24 is opposite to the traveling direction of the intermediate transfer belt 125 (clockwise direction in FIG. 2). As a result, the cleaning roller 24 scrapes off the residual toner adhered to the surface of the intermediate transfer belt 125 at the portion in contact with the intermediate transfer belt 125. The scraped residual toner is collected by a cleaning blade 25 disposed at a position downstream of the intermediate transfer belt 125 in the running direction and below the cleaning roller 24.

  The sheet feeding unit 14 includes a manual feed tray 141 that can be freely opened and closed on the right side wall in FIG. 1 of the apparatus main body 11, and a sheet feeding cassette 142 that is detachably mounted at a position below the exposure apparatus 124 in the lower body 111. , 143, 144.

  The manual feed tray 141 is a tray that is provided at a lower position on the right surface of the lower main body 111 and feeds recording paper toward the image forming unit 12 by a manual feed operation. The paper feed cassettes 142, 143, and 144 store paper bundles in which a plurality of recording papers are stacked. A pickup roller 145 is provided above the paper feed cassettes 142, 143, and 144, and the pickup roller 145 transfers the uppermost recording paper in the paper bundle stored in the paper feed cassettes 142, 143, and 144 to the paper transport path 190. Move out toward.

  The paper discharge unit 15 is formed between the lower main body 111 and the upper main body 112. The paper discharge unit 15 includes a discharge tray 151 formed on the upper surface of the lower main body 111. The discharge tray 151 is a tray in which the recording paper on which the toner image is formed by the image forming unit 12 is discharged after the fixing process is performed by the fixing device 13.

  Next, the configuration of the image forming apparatus 1 will be described. FIG. 2 is a functional block diagram schematically showing the main internal configuration of the image forming apparatus 1. 3A and 3B are diagrams showing an outline of the internal mechanism of the paper feed cassettes 142 and 143. FIG.

  The image forming apparatus 1 includes a control unit 10. The control unit 10 includes a CPU (Central Processing Unit), a RAM, a ROM, a dedicated hardware circuit, and the like, and controls overall operation of the image forming apparatus 1.

  The control unit 10 includes an original reading unit 5, an image processing unit 31, an image memory 32, a paper transport unit 411, an image forming unit 12, a driving roller driving unit 164, an operation unit 47, a facsimile communication unit 71, a network interface unit 91, and an HDD. (Hard disk drive) 81, the secondary transfer roller driving unit 162, the cleaning unit 22, and the registration sensor 63 are connected. The control unit 10 performs operation control of each of the connected mechanisms and transmits / receives a signal or data to / from each mechanism.

  The control unit 10 includes an operation control unit 100 that performs overall operation control of the image forming apparatus 1 described above. The operation control unit 100 executes operation control for each function of the scanner function, the printer function, the copy function, and the printer function in accordance with a job execution instruction input from the user through the operation unit 47 or a personal computer connected via a network. The driving and processing of each mechanism unit necessary for the purpose is controlled. Further, the operation control unit 100 executes the image forming jobs received by the job receiving unit 102, which will be described later, in the execution order determined for each image forming job. In other words, the operation control unit 100 controls the operation of each mechanism of the image forming apparatus 1 according to the content indicated by the image forming job to perform the image forming operation.

  The document reading unit 5 includes a scanner unit 51 including the reading mechanism 163 having an image irradiation lamp 511 and a CCD (Charge Coupled Device) sensor 512. The document reading unit 5 irradiates the document with the image irradiation lamp 511 and receives the reflected light with the CCD sensor 512 to read the image from the document.

  The image processing unit 31 performs image processing on the image data of the image read by the document reading unit 5 as necessary. For example, the image processing unit 31 performs predetermined image processing in order to improve the quality after the image read by the document reading unit 5 is formed by the image forming unit 12.

  The image processing unit 31 includes a correction unit 311 and an image processing unit 312. The correction unit 311 outputs the output voltage of the charging device 123 as the image output process data of the image forming unit 12, the exposure light amount of the exposure device 124, the development bias voltage of the development device 122, the transfer bias of the transfer roller 126, and the secondary transfer roller 210. Adjust the transfer bias and other values. For example, the image processing unit 312 performs predetermined correction processing such as level correction and gamma correction on the image data read by the document reading unit 5, or compression or expansion processing, and expansion or reduction processing of the image data Various processing processes such as are performed. The image data processed by the image processing unit 31 is stored in the image memory 32 or output to the image forming unit 12 or the facsimile communication unit 71 or the like.

  The image memory 32 stores image data read by the document reading unit 5.

  The sheet conveying unit (conveying unit) 411 includes the pickup roller 145 and the conveying roller 192 shown in FIG. 1, and records the recording sheets stored in the manual feed tray 141 and the sheet feeding cassettes 142 and 143 to the image forming unit 12 and It is conveyed to the discharge tray 151.

  As described above, the image forming unit 12 includes the image forming units 12M, 12C, 12Y, and 12B, the intermediate transfer belt 125 stretched around the driving roller 125a, and the secondary transfer roller 210. The image data to be output by the image forming unit 12 is transmitted from image data read by the document reading unit 5, image data transmitted from a client computer or the like in the local area via the network interface unit 91, and the like. Image data.

  As shown in FIG. 1 in addition to FIG. 2, the operation unit 47 includes a touch panel unit and operation key units that receive instructions from the user regarding various operations and processes that can be executed by the image forming apparatus 1. The touch panel unit includes a display unit 473 such as an LCD (Liquid Crystal Display) provided with a touch panel.

  The facsimile communication unit 71 includes an unillustrated encoding / decoding unit, modulation / demodulation unit, and NCU (Network Control Unit), and performs facsimile transmission using a public telephone network. For example, the facsimile communication unit 71 transmits image data of a document read by the document reading unit 5 to a facsimile device or the like via a telephone line, or receives image data transmitted from the facsimile device or the like.

  The HDD 81 stores image data read by the document reading unit 5 and the like. The image data stored in the HDD 81 is used for image formation by the image forming unit 12 and can be transmitted to a client computer connected to the image forming apparatus 1 via a network.

  The network interface unit 91 includes a communication module such as a LAN board, and transmits / receives various data to / from a device (such as a personal computer) in the local area via the LAN connected to the network interface unit 91.

  The driving roller driving unit 164 is a motor and a driver for rotationally driving the driving roller 125a on which the intermediate transfer belt 125 is stretched.

  The secondary transfer roller driving unit 162 is a motor and driver for rotationally driving the secondary transfer roller 210 that transfers the toner image formed on the intermediate transfer belt 125 onto the recording paper. The transfer bias unit is included in the secondary transfer roller driving unit 162.

  As described above, the cleaning unit 22 includes, for example, the cleaning roller 24, the cleaning blade 25, and a drive source (not shown), and is driven and controlled by the operation control unit 100.

  The registration sensor 63 is positioned opposite to the light emitting unit, and a light emitting unit disposed on one side wall of the paper conveyance path 190 on the upstream side in the paper conveyance direction by the paper conveyance unit 411 with respect to the registration roller 630. And a light receiving portion disposed on the other side wall portion for receiving light from the light emitting portion. In response to a paper delay determination unit 104, which will be described later, the light receiving unit outputs a High signal when receiving light from the light emitting unit, and outputs a Low signal when not receiving light from the light emitting unit. That is, when a recording sheet exists between the light emitting element and the light receiving element of the registration sensor 63 in the paper transport path 190, a low signal is output from the light receiving unit.

  Further, the control unit 10 further includes a storage number calculation unit 101, a job reception unit 102, a paper delay determination unit 104, a cleaning control unit 105, a first determination unit 106, a second determination unit 107, a type storage unit 1071, and a supply unit. A paper mechanism switching unit 108 is provided. Note that the type storage unit 1071 only needs to be provided when necessary in the execution control of the image forming job described later. The control unit 10 may function as each of these units according to an operation control program stored in the built-in ROM or the like, or each unit may be provided with a hardware circuit.

  The stored number calculation unit 101 detects the number of recording media stored in each of the paper feed mechanisms (in this embodiment, the paper feed cassettes 142 to 144) provided in the image forming apparatus 1. The stored number calculation unit 101 includes, for example, (1) an elevating plate 146 that raises and lowers a bundle of recording sheets and contacts and separates the pickup roller 145 inside each of the paper feeding cassettes 142, 143, and 144. A distance measuring sensor 147 having a light emitting unit and a light receiving unit is installed above. The distance measuring sensor 147 measures the distance to the top surface of the sheet bundle S when the elevating plate 146 is at the retracted position shown in FIG. 3A, and outputs the detected distance to the stored number calculating unit 101. The storage number calculation unit 101 calculates the value of the number of recording sheets corresponding to the detection distance obtained from the distance measuring sensor 147 from the calculation table or reads it from the data table storing the correlation between the detection distance and the number of recording sheets. Is the number of sheets stored in each sheet cassette.

  Further, at the time of image formation, the rotating support shaft 1461 provided on the inner bottom of the paper feed cassettes 142 to 144 is rotated as a rotation shaft, and the lifting plate 146 is the end opposite to the rotation support shaft 1461. 3B, the recording paper can be taken out by the pickup roller 145 as shown in FIG. 3B, but the paper feed cassettes 142 to 144 are fed by the pickup roller 145. A counter switch 148 that is turned on by being pressed by the recording sheet when the recording sheet is discharged near the discharge port of the recording sheet taken out from the cassettes 142 to 144 is output to the stored number calculation unit 101. It is provided for each. The stored sheet number calculation unit 101 subtracts the count value of each of the paper feed cassettes 142 to 144 obtained from the counter switch 148 from the calculated or read value of the number of recording sheets, thereby supplying paper even when image formation is performed. The number of stored sheets (remaining number) of the paper cassettes 142 to 144 is calculated as needed.

  The stored number calculation unit 101, the distance measuring sensor 147, and the counter switch 148 function as a stored number detection unit. Further, the method for detecting the number of stored sheets in the paper feed cassettes 142 to 144 by the stored number detection unit is not limited to the above, and other methods for detecting the number of stored sheets may be employed.

  The job receiving unit 102 receives an image forming job specifying a paper feed mechanism used for image formation. The image forming job is input by the operation of the operation unit 47 by the user or received by the network interface unit 91 from a client computer connected to the image forming apparatus 1 via the network, and is received by the job receiving unit 102. The job receiving unit 102 can receive a plurality of image forming jobs, and stores the image forming jobs together with the execution order of the image forming jobs. Note that the image forming job includes information on which paper feeding mechanism (in this embodiment, the paper feeding cassettes 142 to 144) is used for recording paper used for image formation.

  The paper delay determination unit (delay determination unit) 104 determines whether the conveyance of the recording paper by the paper conveyance unit 411 is delayed at the image transfer timing at which the toner image is transferred from the intermediate transfer belt 125 to the recording paper by the secondary transfer roller 210. Determine whether or not. At the time of image formation based on the execution of the image formation job, the paper delay determination unit 104 determines whether the image formation starts based on the image formation start timing by the image formation unit 12 and the traveling speed of the intermediate transfer belt 125 by the operation control unit 100. The arrival time of the toner image formed on the transfer belt 125 at the nip N (the toner image transfer position from the intermediate transfer belt 125 to the recording paper) is calculated.

  Then, the paper delay determining unit 104 determines that the recording paper (the leading end portion of the recording paper in the transport direction) in the paper feeding mechanism that has been transported by the paper transport unit 411 is a predetermined time before the arrival time. (The time required for the transported recording paper to reach the nip portion N from the position at which the registration sensor 63 is disposed) does not reach the position at which the registration sensor 63 is disposed before the registration sensor 63 is reached. When the Low signal from the light receiving unit is not received (when the High signal is received), it is determined that the conveyance of the recording sheet to the nip portion N by the sheet conveying unit 411 is delayed with respect to the image transfer timing.

  Further, the paper delay determination unit 104 reaches the position where the registration sensor 63 is arranged by a predetermined time before the arrival time, and receives the LOW signal from the light receiving unit of the registration sensor 63. When it is received (when the High signal is not received), it is determined that the conveyance of the recording paper to the nip portion N is not delayed with respect to the image transfer timing.

  That is, the paper delay determination unit 104 and the registration sensor 63 detect whether the conveyance of the recording paper by the paper conveyance unit 411 is delayed with respect to the image transfer timing by the secondary transfer roller 210 as a paper delay detection unit.

  The cleaning control unit 105 controls the operation of the cleaning unit 22.

  When the paper delay determination unit 104 and the registration sensor 63 detect a recording paper conveyance delay, the first determination unit 106 determines the number of recording media necessary for the remaining image formation in the image forming job currently being executed. Is determined based on the number of recording sheets on which image formation has been completed up to this point and information on the number of recording sheets on which image formation is included in the image forming job. Then, the first determination unit 106 determines that the number of recording media necessary for the remaining image formation in the image forming job being executed is one of the paper feed cassettes 142 to 144 used for executing the image forming job. It is determined whether or not the number of stored sheets is larger than the number of stored sheets detected by the calculation of the stored sheet number calculating unit 101.

  The second determination unit 107 has the number of recording media necessary for the remaining image formation in the image forming job being executed by the first determination unit 106 larger than the stored number calculated by the stored number calculation unit 101. The number of recording media necessary for the remaining image formation is different from the paper feed cassette used for the image forming job being executed, and the image forming job It is determined whether the number of stored sheets is equal to or less than the number of stored sheets calculated by the stored sheet number calculating unit 101 for the sheet cassette applicable to the above.

  The type storage unit 1071 is a part of the second determination unit 107 in this embodiment, and stores the type of each recording medium stored in the paper feed cassettes 142 to 144 for each of the paper feed cassettes 142 to 144. To do. The recording medium type is, for example, a paper size (A3, A4, B5, B4, Letter size...) Or the like.

  The paper feed mechanism switching unit 108 calculates, by the second determination unit 107, the number of recording media necessary for the remaining image formation in the image forming job that is being executed for the paper feeding mechanism applicable to the image forming job. If it is determined that the number of stored sheets is equal to or less than the number of stored sheets, the sheet cassette used for the image forming job being executed is changed to another applicable sheet cassette. Switch.

  Next, execution control of the image forming job by the image forming apparatus 1 will be described. FIG. 4 is a flowchart showing execution control of the image forming job by the image forming apparatus 1.

  When an image forming job is input by the operation of the operation unit 47 by the user or received from the client computer by the network interface unit 91 and received by the job reception unit 102 (YES in S1), the operation control unit 100 displays the image. The execution of the forming job is started, and a series of operation control based on the image forming job is performed. The operation control unit 100 first causes the image forming unit 12 to start image formation on the intermediate transfer belt 125 (S2). Then, the operation control unit 100 causes the paper transport unit 411 to transport the recording paper from the paper feed mechanism (any of the paper feed cassettes 142 to 144) designated to be used for image formation in the image forming job (S3). ).

  After starting the conveyance of the recording paper, the paper delay determination unit 104 detects the recording paper by the paper conveyance unit 411 with respect to the image transfer timing at which the toner image is transferred from the intermediate transfer belt 125 to the recording paper by the secondary transfer roller 210. The above-described determination of whether or not the conveyance is delayed is started (S4). Here, the paper delay determination unit 104 detects the presence or absence of a delay in the transported recording paper based on the signal output from the registration sensor 63, and a delay occurs in the transported recording paper. If it is detected that the sheet is not detected (NO in S4), the operation control unit 100 adjusts the recording paper conveyance timing by the registration roller 630 and then performs the intermediate transfer by the secondary transfer roller 210 at the nip N. The toner image on the belt 125 is transferred to the recording paper (S10). The recording paper on which the toner image has been transferred is discharged onto the discharge tray 151 by the paper transport unit 411 under the control of the operation control unit 100 (S11). Thereafter, the operation control unit 100 determines whether or not there is a remaining page on which image formation is to be performed based on the content indicated by the image forming job being executed (S12), and determines that there is a remaining page. In this case (YES in S12), the process returns to S2, and the processes after S2 are performed on the remaining page.

  If the operation control unit 100 determines that there is no remaining page on which image formation is to be performed (NO in S12), the operation control unit 100 is received by the job reception unit 102 and is waiting for the execution order. It is determined whether there is another image forming job (S13). If the operation control unit 100 determines that there is an image forming job waiting for the execution order (YES in S13), the process returns to S2, and the operation control unit 100 waits for the execution order. Among the forming jobs, execution of an image forming job having the next execution order is started, and the processes after S2 are performed. If the operation control unit 100 determines that there is no other image forming job waiting for the execution order (NO in S13), the process ends.

  On the other hand, when the paper delay determination unit 104 detects that a delay has occurred in the transported recording paper in S4 (YES in S4), the first determination unit 106 For the paper feed cassette used for the image forming job executed in step 1, the number of stored sheets calculated by the stored number calculation unit 101 at that time is acquired from the stored number calculation unit 101, and the image being executed It is determined whether or not the number of recording media necessary for the remaining image formation in the forming job is larger than the acquired number of stored sheets (S5). For the sake of clarity, the paper feed cassette will be described as a paper feed cassette 142 hereinafter.

  When the first determination unit 106 determines in S5 that the number of recording media necessary for the remaining image formation in the image forming job being executed is greater than the acquired number of stored sheets (YES in S5). Subsequently, the second determination unit 107 has the same type of recording medium as the type of recording medium stored in the type storage unit 1071 for the paper feed cassette 142 used for the image forming job being executed. It is determined whether there is another paper feed cassette stored in (S6). The other sheet feeding cassette is one of the sheet feeding cassettes 143 and 144 in the description of the present embodiment. In this embodiment, the recording medium type will be described as a paper size.

  Here, the second determination unit 107 has the same type of recording medium as the type of recording medium stored in the type storage unit 1071 for the paper feeding cassette 142 used for the image forming job being executed. For example, A4 recording paper having the same size as the recording paper size A4 stored in the paper feeding cassette 142 used for the image forming job being executed. When it is determined that there is another sheet feeding cassette 143 that stores the image (YES in S6), the second determination unit 107 further determines that the number of recording media necessary for the remaining image formation is the new another It is determined whether or not the sheet feeding cassette 143 is equal to or smaller than the number of stored sheets calculated by the stored number calculation unit 101 at this time (S7).

  In S <b> 7, the second determination unit 107 further determines that the number of recording media necessary for the remaining image formation is equal to or less than the number of stored sheets by the stored number calculation unit 101 calculated for the other sheet feeding cassette 143. If so (YES in S7), the paper feed mechanism switching unit 108 switches the paper feed cassette 142 used for the image forming job being executed to the other paper feed cassette 143 (S8).

  After switching the paper feed cassette, the cleaning control unit 105 causes the cleaning unit 22 to clean the intermediate transfer belt 125 (S9). After this cleaning, the process proceeds to S12. The operation control unit 100 resumes the image forming job, and if there is a page for which image formation has not been completed in the image forming job (YES in S12), the operation control unit 100 performs the processing from S2 on the incomplete page. If there is no page for which image formation has not been completed in the image forming job (NO in S12), the operation control unit 100 ends the image forming job and waits for the next image forming job to be executed. The process proceeds to (S13).

  On the other hand, when the first determination unit 106 determines in S5 that the number of recording media required for the remaining image formation in the image forming job being executed is equal to or less than the acquired storage number (NO in S5). In S6, the second determination unit 107 determines that there is no other paper feed cassette that stores a recording medium of the same size as the paper feed cassette 142 used in the image forming job being executed ( (NO in S6), and in S7, the second determination unit 107 determines that the number of recording media necessary for the remaining image formation is larger than the number of recording sheets stored in the other sheet feeding cassette 143. In this case (NO in S7), the cleaning control unit 105 does not switch the intermediate transfer belt 125 to the cleaning unit 22 without switching the paper feeding cassette by the paper feeding mechanism switching unit 108. To perform the training (S9).

  After this cleaning, the process moves to S12, and the subsequent processing is continued using the paper feeding cassette that has been used without changing the paper feeding cassette.

  For example, if the transfer of the recording medium to the transfer position of the toner image by the intermediate transfer belt 125 and the secondary transfer roller 210 is delayed with respect to the transfer timing of the toner image during the execution of the image forming job, the image formation is performed at this time. Even if the intermediate transfer belt 125 is cleaned immediately after the interruption, if the paper feed cassette is later switched to another paper feed cassette due to a shortage of recording paper, the change of the recording medium conveyance path by the switching or the Depending on the paper feed start timing from the paper feed mechanism, etc., there is a possibility that the transfer of the recording medium from the paper feed mechanism after the switching is delayed with respect to the transfer timing of the toner image. It becomes necessary to perform cleaning again.

  In contrast, according to the present embodiment, the conveyance of the recording paper from the switched paper feed cassette (the paper feed cassette 143 in the above) is started after the cleaning of the intermediate transfer belt 125 by the cleaning unit 22. In addition, since the processing and operation necessary for changing the recording medium conveyance path by switching can be completed while the operation time for the cleaning elapses, the sheet feeding from another sheet feeding cassette 143 is immediately performed after the switching. Even if the paper is started, the possibility that the recording medium conveyance is delayed with respect to the toner image transfer timing is reduced. For this reason, it is possible to reduce the number of cleaning operations of the intermediate transfer belt 125 when it is necessary to switch the paper feed cassette.

  As a result, in this embodiment, the performance of cleaning the residual toner on the intermediate transfer belt 125 is not particularly deteriorated, and the occurrence of a situation that requires cleaning can be prevented in advance and the cleaning time can be reduced. The productivity of image formation by the apparatus 1 can be increased.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the above embodiment, the second determination unit 107 sets the same recording medium type as the recording medium type stored in the type storage unit 1071 for the paper feeding cassette 142 used for the image forming job being executed. In the determination of whether there is another paper feed cassette stored in the storage unit 1071 (S6), the recording medium type has been described as the paper size. However, the present invention is not limited to this, and other determination methods can be used.

  For example, the type storage unit 1071 similarly stores the recording paper size, and the second determination unit 107 stores the recording medium stored in the paper feed cassette used in the image forming job being executed. A paper feed cassette that stores a recording medium having an image forming area having an area larger than that of the image forming area may be determined as the other paper feeding cassette.

  In this case, even if the paper feed mechanism switching unit 108 switches the paper feed cassette used for image formation to the other paper feed cassette, the image formation on the recording medium used so far is processed such as reduction. Even if the recording medium is another recording medium supplied from the other sheet feeding cassette, the same contents can be used.

  In the above embodiment, the image forming apparatus according to the present invention has been described as a multifunction peripheral. However, the image forming apparatus according to the present invention is not limited to this. For example, the image forming apparatus according to the present invention may be a copier, a facsimile machine, or the like.

  The configurations and processes shown in the above embodiments using FIGS. 1 to 4 are only one embodiment of the present invention, and the present invention is not limited to the configurations and processes.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Control unit 22 Cleaning part 47 Operation part 63 Registration sensor 100 Operation control part 101 Storage number calculation part 102 Job reception part 104 Paper delay determination part 105 Cleaning control part 106 1st determination part 107 2nd determination part 1071 Type Storage unit 108 Paper feed mechanism switching unit 147 Distance sensor 148 Counter switch 192 Conveying roller

Claims (3)

A plurality of paper feed mechanisms for storing recording media;
A stored number detection unit for detecting the number of recording media stored in each of the paper feed mechanisms;
An intermediate transfer belt stretched between a plurality of rollers so as to be able to run endlessly;
An image forming unit for forming a toner image on the intermediate transfer belt;
A transfer unit for transferring a toner image formed on the intermediate transfer belt to a recording medium passing between the intermediate transfer belt;
A transport unit that transports a recording medium stored in the paper feeding mechanism to a transfer position of the toner image by the transfer unit;
A cleaning unit that performs a cleaning operation to remove residual toner from the intermediate transfer belt;
A job accepting unit that accepts a plurality of image forming jobs specifying the paper feeding mechanism in which a recording medium to be conveyed to the conveying unit is stored;
During execution of an image forming job accepted by the job accepting unit, a delay detecting unit detects whether the conveyance of the recording medium to the transfer position by the conveying unit is delayed with respect to the image transfer timing by the transfer unit. When,
A cleaning control unit for causing the cleaning unit to perform the cleaning operation;
When the delay detection unit detects the conveyance delay of the recording medium, the number of recording media necessary for the remaining image formation in the image forming job currently being executed is used for the execution of the image forming job. A first determination unit that determines whether or not the sheet feeding mechanism is greater than the stored number of sheets detected by the stored number of sheets detection unit;
When the first determination unit determines that the number of recording media required for the remaining image formation is larger than the storage number detected by the storage number detection unit, it is necessary for the remaining image formation. The number of recording media is a paper feed mechanism different from the paper feed mechanism used for the image forming job being executed, and the stored number detection unit for the paper feed mechanism applicable to the image forming job A second determination unit that determines whether the number of stored sheets is equal to or less than the number of stored sheets detected by
When it is determined by the second determination unit that the number of recording media necessary for the remaining image formation is equal to or less than the number of stored sheets by the stored number detection unit detected for the applicable sheet feeding mechanism. A paper feed mechanism switching unit that switches the paper feed mechanism used for the image forming job being executed to the applicable paper feed mechanism;
The cleaning control unit is an image forming apparatus that causes the cleaning unit to perform the cleaning operation after the sheet feeding mechanism is switched by the sheet feeding mechanism switching unit. A type storage unit for storing the type of the recording medium stored in the paper feed mechanism for each paper feed mechanism;
The second determination unit stores in the type storage unit the same recording medium type as the recording medium type stored in the type storage unit for the paper feed mechanism used in the image forming job being executed. The image forming apparatus according to claim 1, wherein the another sheet feeding mechanism is the applicable sheet feeding mechanism.   The second determination unit is a type of a recording medium having an image forming area having an area equal to or larger than an image forming area of the recording medium stored in the paper feeding mechanism used in the image forming job being executed. 3. The image formation according to claim 2, wherein another paper feeding mechanism stored in the type storage unit is determined as another paper feeding mechanism in which the same recording medium type is stored in the type storage unit. apparatus.

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