JP2012042901A - Image forming apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and a program suppressing adhesion of a developer to fixing means forming a developer image when a recording medium having a conveyance-direction length different from a predetermined length is conveyed with the developer image formed thereon.SOLUTION: This image forming apparatus includes a detecting unit 91 for detecting the length of recording paper P in a conveyance-direction upstream side of a secondary transfer unit 37, when recording paper P having the length different from the predetermined length is detected by the detecting unit 91, controls not to apply a voltage to the secondary transfer unit 37, and when the conveyance-direction tip end side of the recording paper P in a region where no voltage has been applied reaches a fixing device 100, controls to stop the conveyance of the recording paper P.

Description

  The present invention relates to an image forming apparatus and a program.

  Patent Document 1 discloses a display unit, a recording unit that records data, a control unit, a unit that sets the size of a sheet to be fed, and a sensor that detects the size of a sheet that is actually conveyed on a conveyance path. And a timer for setting a timer value for determining a jam when the paper transport time exceeds a predetermined time, and setting a timer value for determining a jam according to the size of the paper detected by the sensor. An image forming apparatus is disclosed which is characterized by being changed.

  Patent Document 2 discloses a plurality of image forming units that are spaced apart from each other by a predetermined distance in the sheet conveyance direction of the sheet conveyance path, and a sheet that is disposed upstream of the plurality of image forming units in the conveyance direction. A paper edge detector that detects the leading edge of a sheet conveyed on the conveying path and outputs a leading edge detection signal, and detects a trailing edge of a sheet shorter than a predetermined sheet length and outputs an abnormal trailing edge detection signal. When the leading edge detection signal is input from the sheet edge detection unit, the exposure start time for each image forming unit is calculated from the sheet conveyance speed and the distances between the sheet detection unit and the image forming unit on the sheet conveyance path. When an abnormal trailing edge detection signal is input from the exposure start time calculating means and the sheet edge detection unit, image formation is performed based on the sheet conveyance speed and the distance between the sheet edge detection unit and the image forming unit on the sheet conveyance path. When exposure is prohibited to calculate the exposure prohibited time for each copy When the calculation unit, the sheet end detection unit, the exposure start time calculation unit, and the exposure prohibition time calculation unit are controlled to expose and transfer an image for each image forming unit, and a sheet shorter than a predetermined sheet length is received, There is disclosed an image forming apparatus comprising: a control unit that prohibits exposure to a portion lacking from a predetermined sheet length for each forming unit.

JP 2001-151383 A JP 2003-323020 A

  It is an object of the present invention to control the transfer unit so that no voltage is applied to the transfer unit and stop the conveyance of the recording medium when the leading end side in the conveyance direction of the area where the voltage of the recording medium is not applied reaches the fixing unit. The developer that formed the developer image is fixed when a recording medium having a length different from the predetermined length in the conveyance direction is conveyed in a state where the developer image is formed. It is an object to provide an image forming apparatus and a program that suppress the adhesion to the means.

  In order to achieve the above object, the image forming apparatus according to claim 1 includes a transfer unit that transfers a developer image held on the peripheral surface of the image holding member to a recording medium when a voltage is applied thereto, and the transfer unit. A conveying unit that conveys the recording medium so as to sequentially pass through a fixing unit that contacts the developer image transferred to the recording medium by a transfer unit and fixes the developer image on the recording medium; and the transfer unit A detection unit that detects the length of the recording medium on the upstream side in the transport direction, and a control that prevents the voltage from being applied to the transfer unit when a length different from a predetermined length is detected by the detection unit And a control means for controlling the conveying means so that the conveyance of the recording medium is stopped when the leading end side in the conveying direction of the area where the voltage of the recording medium is not applied reaches the fixing means. In is configured.

  According to a second aspect of the present invention, the image forming apparatus according to the first aspect of the present invention is configured so that the conveyance of the recording medium is stopped after the control unit is controlled not to apply the voltage to the transfer unit. The time until the conveying means is controlled is the distance from the transfer position at which the developer image is transferred to the recording medium by the transfer means to the fixing position at which the developer image is fixed on the recording medium by the fixing means. And the time derived based on the conveyance speed of the recording medium.

  According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the fixing unit is transferred to the recording medium at a position where the leading end side of the region in the transport direction reaches the fixing unit. The position is in contact with the developer image.

  According to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, wherein the fixing unit is rotatable so that the recording medium is transported in the transport direction. And a pair of rotators for fixing the developer image to the recording medium with the recording medium and the developer image formed on the recording medium sandwiched between the outer peripheral surfaces of the recording medium.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, an alarm is issued when a length different from the predetermined length is detected by the detection means. Is further included.

  According to a sixth aspect of the present invention, there is provided a program for transferring a developer image held on a peripheral surface of an image holding member to a recording medium by applying a voltage to the recording medium, and the transfer means to the recording medium. The length of the recording medium being conveyed by the conveying means that conveys the recording medium so as to sequentially pass through a fixing means that contacts the transferred developer image and fixes the developer image to the recording medium. Means for controlling so that the voltage is not applied to the transfer means when a length different from a predetermined length is detected by a detection means for detecting upstream of the transfer means in the transport direction; and the voltage of the recording medium For functioning as a means for controlling the conveying means so as to stop the conveyance of the recording medium when the leading end side in the conveying direction of the area where no toner is applied reaches the fixing means A.

  According to the first and sixth aspects of the invention, the recording medium is controlled when the leading end side in the transport direction of the area where the voltage of the recording medium is not applied is controlled so that no voltage is applied to the transfer unit, and reaches the fixing unit. Compared to the case where control is not performed to stop the conveyance of the developer image, the developer image is formed when a recording medium having a length different from the predetermined length in the conveyance direction is conveyed in a state where the developer image is formed. An effect of suppressing the formed developer from adhering to the fixing unit can be obtained.

  According to the second aspect of the invention, the time from when the voltage is applied to the transfer unit until the conveyance unit is controlled so as to stop the conveyance of the recording medium is determined from the fixing position to the transfer position. Compared to the case where the time is not derived based on the distance and the conveyance speed of the recording medium, it is easy to convey the recording medium when the leading end side in the conveyance direction of the area where the voltage of the recording medium is not applied reaches the fixing unit. The effect of stopping is obtained.

  According to the third aspect of the present invention, the position at which the leading end side in the conveyance direction of the region where the voltage of the recording medium is not applied reaches the fixing unit is the position where the fixing unit contacts the developer image transferred to the recording medium. The developer that formed the developer image is fixed when a recording medium having a length different from the predetermined length in the conveyance direction is conveyed in a state where the developer image is formed. The effect of further suppressing the adhesion to the means can be obtained.

  According to the fourth aspect of the present invention, the recording medium is rotatably provided so as to be conveyed in the conveying direction, and the development is performed by sandwiching the recording medium and the developer image formed on the recording medium with each outer peripheral surface. As compared with the case where there is no pair of rotating bodies for fixing the agent image on the recording medium, an effect of easily pulling out the recording medium from the fixing unit while suppressing the adhesion of the developer to the fixing unit can be obtained.

  According to the fifth aspect of the present invention, the length in the transport direction of the recording medium being transported is determined in advance as compared with a case where no alarm is issued when a length different from the predetermined length is detected by the detection means. The effect of easily grasping that the length is different from the obtained length is obtained.

1 is a side cross-sectional view illustrating an example of a configuration of an image forming apparatus according to an embodiment. It is a schematic diagram which shows an example of arrangement | positioning of the detection part which concerns on embodiment. It is a block diagram showing an example of an image forming unit according to an embodiment. 1 is a block diagram illustrating a main configuration of an electrical system of an image forming apparatus according to an embodiment. It is a flowchart which shows the flow of a process of the stop control processing program which concerns on embodiment.

  Hereinafter, an example of an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a front view of an image forming apparatus 10 as an example of the present embodiment. The image forming apparatus 10 includes a sheet storage unit 12 that stores recording paper P from the lower side to the upper side in the vertical direction (the arrow Y direction in the drawing), and the sheet storage unit 12 that is provided on the sheet storage unit 12. An image forming unit 14 that forms an image on the recording paper P supplied from the paper, a discharge unit 16 that is integrally provided on the upper left side of the image forming unit 14 and discharges the recording paper P on which the image is formed, A document reading unit 18 provided on the image reading unit G for reading the read document G, and a control unit 20 provided inside the image forming unit 14 as a control unit for controlling the operation of each unit of the image forming apparatus 10 are configured. Yes. In the following description, the vertical direction of the image forming apparatus 10 is described as an arrow Y direction, and the horizontal direction is described as an arrow X direction. In addition, left and right indicate left and right when the image forming apparatus 10 is viewed from the front.

  In the paper storage unit 12, the first storage unit 22, the second storage unit 24, the third storage unit 26, and the fourth storage unit 28 in which recording papers P having different sizes as an example of a recording medium are stored are in the arrow Y direction. It is provided side by side. The first storage unit 22, the second storage unit 24, the third storage unit 26, and the fourth storage unit 28 send out the stored recording paper P to the conveyance path 30 provided inside the image forming apparatus 10. A roll 32 is provided, and a pair of conveyance rolls 34 and a conveyance roll 36 for conveying the recording paper P one by one are provided on the downstream side of the delivery path 32 in the conveyance path 30. Further, the recording paper P is stopped once in the conveyance direction of the recording paper P in the conveyance path 30 and in the image forming unit 14 in the downstream direction of the conveyance roll 36, and to the secondary transfer unit 37 at a predetermined timing. An alignment roll 38 is provided.

  The image forming unit 14 includes a housing 16A that is an apparatus main body. In the housing 16 </ b> A, the upper left portion of the image forming unit 14 protrudes above the upper center portion and the upper right portion in a front view of the image forming apparatus 10. The left end of the document reading unit 18 is coupled to the upper end of the discharge unit 16. As a result, the image forming apparatus 10 has a discharge area 19 surrounded by the upper surface of the image forming unit 14, the lower surface of the document reading unit 18, and the right side surface of the discharge unit 16. In the discharge area 19, the recording paper P is discharged and stacked from the discharge unit 16.

  A foldable manual sheet feeding unit 39 provided on the left side of the image forming apparatus 10 on the opposite side of the conveyance roll 36 of the fourth storage unit 28 across the conveyance path 30 of the image forming unit 14. A preliminary transport path 40 through which the recording paper P is transported to the transport path 30 is provided. The preliminary conveyance path 40 includes a delivery roll 42 that sends the recording paper P of the manual paper feed unit 39 to the preliminary conveyance path 40, and a plurality of recording papers P that are provided downstream of the delivery roll 42 and convey the recording paper P one by one. A transport roll 44 is provided, and the downstream end of the preliminary transport path 40 is connected to the transport path 30.

  Further, a fixing device 100 is provided in the image forming unit 14 on the downstream side of the secondary transfer unit 37 in the conveyance path 30. The fixing device 100 includes a fixing roll 102 that heats the developer on the recording paper P, and a pressure roll 104 that presses the recording paper P toward the fixing roll 102, and the recording paper P is the fixing roll 102. When the toner passes through a nip portion N that is a contact portion between the pressure roller 104 and the pressure roll 104, the developer is melted and solidified to fix the developer image on the recording paper P. In the image forming apparatus 10 according to the present embodiment, a two-component developer mainly including a toner and a carrier is employed as the developer. Hereinafter, the developer is referred to as “toner”. .

  Further, the image forming unit 14 includes a detection unit 91 that detects the leading end and the trailing end of the recording paper P in the conveyance direction. FIG. 2 schematically illustrates an installation example of the detection unit 91 according to the present embodiment. As shown in the figure, an alignment roll 38, a secondary transfer unit 37, and a fixing device 100 are sequentially arranged in the conveyance path 30 from the upstream side to the downstream side in the conveyance direction. It is arrange | positioned rather than the position alignment roll 38 in the conveyance direction upstream. The detection unit 91 detects the leading edge and the trailing edge of the recording paper P, outputs a leading edge detection signal when the leading edge of the recording paper P is detected, and outputs a trailing edge detection signal when the trailing edge of the recording paper P is detected. . In the image forming apparatus 10 according to the present embodiment, a reflection type photo interrupter is applied as the detection unit 91. However, the detection unit 91 is not limited thereto, and may be a transmission type photo interrupter. As long as it detects the rear end, any sensor may be used.

  As shown in FIGS. 1 and 3, in the center of the image forming unit 14, toners on the recording paper P are combined with black (K), yellow (Y), magenta (M), and cyan (C) toners. An image forming unit 60 is provided as an example of a forming unit that forms an image. In the image forming unit 60, the photosensitive drums 62K, 62Y, 62M, and 62C that hold the electrostatic latent images correspond to toners of black (K), yellow (Y), magenta (M), and cyan (C). Is provided. In the following description, when it is necessary to distinguish between K, Y, M, and C, an alphabetic character of any one of K, Y, M, and C is added after the numeral, and K, Y is structurally used. , M, and C are omitted, the description of K, Y, M, and C is omitted.

  The photosensitive drums 62K, 62Y, 62M, and 62C are arranged in this order toward the upper right side in the figure, and rotate in the direction of arrow b (counterclockwise direction in the figure) and are formed by light irradiation. The latent image is held on the outer peripheral surface. Further, around each of the photosensitive drums 62K, 62Y, 62M, and 62C, a charging roll 66, an LED (Light Emitting Diode) head 68, a developing device 72, and an intermediate transfer belt 64 (primary transfer) are sequentially arranged along the direction of the arrow b. A roll 74) and a cleaning roll 76 are provided.

  As an example, the charging roll 66 has a configuration in which a plurality of layers (all not shown) including an elastic layer having electrical conductivity, an intermediate layer, and a surface resin layer are formed around a shaft portion made of stainless steel. It has become. The charging roll 66 is rotatably provided with a shaft so that the outer peripheral surface thereof is in contact with the surface layer of the photosensitive drum 62 and is applied with a voltage from a voltage application unit (not shown). The outer peripheral surface of the photosensitive drum 62 is charged by the discharge generated by the above.

  The LED head 68 irradiates (exposes) light corresponding to each toner color on the outer peripheral surface of the photosensitive drum 62 charged by the charging roll 66 to form an electrostatic latent image. As a means for exposing the photosensitive drum 62, a method of scanning laser light with a polygon mirror in common for four colors K, Y, M, and C may be used.

  The developing device 72 includes a developing roll 71 that supplies toner to the electrostatic latent image formed on the photosensitive drum 62 to form a toner image, and conveyance members 73A and 73B that circulate and convey the toner to the developing roll 71. is doing.

  The intermediate transfer belt 64 is formed in an endless shape, and includes a belt conveyance roll 82 provided in the secondary transfer unit 37, a belt conveyance roll 84 provided on the lower right side of the belt conveyance roll 82, and a belt conveyance roll 82. Is wound around a driving roll 86 that is provided on the upper right side of the motor and driven by a motor (not shown), and is supported so as to move around in the direction of arrow a (clockwise direction in the figure). The outer peripheral surface of the intermediate transfer belt 64 is a transfer surface onto which a toner image is transferred. The photosensitive drums 62K, 62Y, 62M, and 62C are provided on the transfer surface from the drive roll 86 to the belt conveyance roll 84 of the intermediate transfer belt 64. Are in contact with each other.

  On the other hand, primary transfer rolls 74 (74K, 74Y, 74M, 74C) are provided on the opposite side of the photosensitive drums 62K, 62Y, 62M, 62C with the intermediate transfer belt 64 interposed therebetween. The primary transfer roll 74 is in contact with the inner peripheral surface of the intermediate transfer belt 64, and is applied with a voltage from a voltage application unit (not shown), thereby causing a photosensitive member due to a potential difference with the grounded photosensitive drum 62. The toner image on the drum 62 is primarily transferred to the transfer surface of the intermediate transfer belt 64. As a result, the toner images are transferred onto the intermediate transfer belt 64 while the intermediate transfer belt 64 makes one round.

  A toner density detection sensor 88 is provided on the opposite side of the intermediate transfer belt 64 from the belt conveyance roll 84. The toner density detection sensor 88 has a function of detecting the density of the toner image transferred to the transfer surface of the intermediate transfer belt 64. Further, a cleaning member 92 that cleans the toner remaining on the transfer surface of the intermediate transfer belt 64 after the secondary transfer is provided on the opposite side of the drive roll 86 across the intermediate transfer belt 64.

  The secondary transfer unit 37 includes a belt conveyance roll 82 around which the intermediate transfer belt 64 is wound, and a secondary transfer roll as an example of conveyance means provided on the opposite side of the belt conveyance roll 82 with the intermediate transfer belt 64 interposed therebetween. 89. The secondary transfer roll 89 is connected to the voltage application unit 90 so that a voltage is applied from the voltage application unit 90. Due to the potential difference between the belt conveyance roll 82 and the secondary transfer roll 89, the secondary transfer roll 89 is placed on the intermediate transfer belt 64. The toner image is configured to be secondarily transferred onto the recording paper P.

  As shown in FIG. 1, toner cartridges 77K, 77Y, 77M, and 77C for storing K, Y, M, and C toners are provided on the right side of the cleaning member 92 of the image forming unit 14 in a replaceable manner. Yes. Further, on the left side of the conveyance path 30 of the image forming unit 14, there is provided a double-sided conveyance path 94 through which the recording paper P is conveyed and reversed in order to form an image on both sides of the recording paper P.

  The double-sided conveyance path 94 is provided on the downstream side of the fixing device 100 in the conveyance direction of the recording paper P in the conveyance path 30 and on the downstream side of the conveyance roll 95 so that the rotation direction can be switched. The other end is connected to the upstream side of the alignment roll 38. The double-sided conveyance path 94 is provided with a plurality of conveyance rolls 97 that convey the recording paper P fed from the conveyance roll 96 toward the alignment roll 38. As a result, at the time of double-sided image formation, the recording paper P on which the toner image is fixed on the front side by the fixing device 100 enters the double-sided conveyance path 94 by the reverse rotation of the conveyance roll 96 and a path switching member (not shown). By entering the alignment roll 38, the front and back of the recording paper P are reversed.

  The recording paper P is discharged to a lower base 52 provided on the upper portion of the image forming unit 14 in the conveyance path 31 branched from the conveyance path 30 to the discharge area 19 side downstream of the conveyance roll 95 in the discharge unit 16. A lower discharge roll 54 is provided. A lower detection unit 55 is provided at a position adjacent to the lower discharge roll 54 to detect the stacking height of the recording sheets P stacked on the lower table 52. Further, an upper discharge roll 57 that discharges the recording paper P to an upper table 56 provided above the lower table 52 is provided in the conveyance path 30 on the downstream side of the conveyance roller 95 in the discharge unit 16. An upper detection unit 58 for detecting the stacking height of the recording sheets P stacked on the upper table 56 is provided at a position adjacent to the upper discharge roll 57.

  On the other hand, the document reading unit 18 includes a document transport device 45 that automatically transports the read document G one by one, a platen glass 47 that is disposed below the document transport device 45 and on which one read document G is placed, and a document A document reading device 49 that reads the read document G conveyed by the conveyance device 45 or the read document G placed on the platen glass 47 is provided. The document conveyance device 45 has an automatic conveyance path 48 in which a plurality of pairs of conveyance rolls 46 are arranged, and a part of the automatic conveyance path 48 is arranged so that the recording paper P passes over the platen glass 47. . The document reading device 49 reads the read document G conveyed by the document conveying device 45 in a state of being stationary at the left end portion of the platen glass 47, or is read on the platen glass 47 while moving in the arrow X direction. It is configured to read G.

  FIG. 4 is a block diagram showing a main configuration of the electrical system of the image forming apparatus 10 according to the present embodiment. As shown in the figure, the image forming apparatus 10 includes a CPU 150, a ROM (Read Only Memory) 152, a RAM (Random Access Memory) 154, an NVM (Non Volatile Memory) 156, a UI (User Interface) panel 158, and a communication. An interface 160 is included.

  The ROM 152 functions as a storage unit that stores in advance a control program for controlling the operation of the image forming apparatus 10, a stop control processing program to be described later, various parameters, and the like. The RAM 154 is used as a work area when executing various programs. The NVM 156 stores various types of information that must be retained even when the power switch of the apparatus is turned off. The UI panel 158 includes a touch panel display or the like in which a transmissive touch panel is superimposed on a display. Various types of information are displayed on the display surface of the display, and various information and instructions are received when the user touches the touch panel. The communication interface 160 is connected to a terminal device 162 such as a personal computer, receives various information such as image information indicating an image to be formed on the recording paper P from the terminal device 162, and receives the status of the image forming apparatus 10 in the terminal device 162. This is for transmitting various types of information such as information indicating.

  The image forming engine unit 14, the CPU 150, the ROM 152, the RAM 154, the NVM 156, the UI panel 158, and the communication interface 160 are connected to each other via a system bus BUS. Therefore, the CPU 150 accesses the ROM 152, RAM 154, and NVM 156, displays various information on the UI panel 158, grasps the contents of user operation instructions on the UI panel 158, and communicates via the communication interface 160 from the terminal device 162. Various types of information are received, various types of information are transmitted to the terminal device 162 via the communication interface 160, the operating state of the image forming unit 14 is grasped, and the operation of the image forming unit 14 is controlled.

  The image forming unit 14 generates a driving force for rotationally driving various rolls for transporting the recording paper P such as delivery rolls 32 and 42, transport rolls 34, 36, 44, 95 and 96, and an alignment roll 38. A motor 14A, a motor control unit 14B that is connected to the motor 14A and controls driving of the motor 14A, a voltage application unit 90, and a detection unit 91 are provided. The motor control unit 14B, the voltage application unit 90, and the detection unit 91 are connected to each other via the system bus BUS. Therefore, the CPU 150 outputs the control of the motor 14A via the motor control unit 14B, the understanding of the operation state of the motor 14A via the motor control unit 14B, the control of the operation of the voltage application unit 90, and the detection unit 91. Receiving the leading edge detection signal and the trailing edge detection signal.

  Next, the operation of the image forming apparatus 10 according to the present embodiment will be described.

  First, an image forming process in the image forming apparatus 10 will be described.

  When the image forming apparatus 10 operates, image data of each color of black (K), yellow (Y), magenta (M), and cyan (C) is transmitted from the image processing apparatus (not shown) or from the outside to the LED head 68 (FIG. 2). Output). Subsequently, the light emitted from the LED head 68 according to the image data exposes the outer peripheral surface (surface) of the photosensitive drum 62 charged by the charging roll 66, and the surface of each photosensitive drum 62 has each color. An electrostatic latent image corresponding to the image data is formed. Further, the electrostatic latent image formed on the surface of each photosensitive drum 62 is developed as a toner image by each developing device 72. Then, the toner image on the surface of each photosensitive drum 62 is sequentially multiplex-transferred onto the intermediate transfer belt 64 by the primary transfer roll 74.

  On the other hand, the recording paper P sent out from the paper storage unit 12 and conveyed through the conveyance path 30 is aligned with the multiple transfer of each toner image onto the intermediate transfer belt 64 by the alignment roll 38 and the secondary transfer unit. It is conveyed to 37. The toner image that has been multiplex-transferred onto the intermediate transfer belt 64 is secondarily transferred by the secondary transfer roll 89 onto the recording paper P that has been conveyed to the secondary transfer unit 37.

  Subsequently, the recording paper P to which the toner image is transferred is conveyed to the fixing device 100. In the fixing device 100, the toner image is fixed on the recording paper P by being heated and pressed by the fixing roll 102 and the pressure roll 104. Further, the recording paper P on which the toner image is fixed is discharged from the discharge unit 16 to the lower table 52 or the upper table 56. When forming images on both sides of the recording paper P, after fixing the image on the front surface by the fixing device 100, the lower end of the recording paper P is fed from the conveying roll 96 to the double-sided conveying path 94 and the alignment roll 38 is used. By sending out to (conveyance path 30), the leading edge and the trailing edge of the recording paper P are switched. Then, image formation and fixing are performed on the back surface of the recording paper P.

  Incidentally, in the image forming apparatus 10 according to the present embodiment, sheet length size information (for example, rated sizes such as A4, A5, and B4) indicating the size of the recording sheet P in the conveyance direction (hereinafter referred to as “sheet length size”). Is designated in advance by the user via the UI panel 158, and the image forming apparatus 10 executes the image forming process described above according to the designated sheet length size information. However, the paper length size indicated by the paper length size information specified in advance by the user via the UI panel 158 and the paper length size of the currently transported recording paper P on which the toner image is formed inside the image forming apparatus 10 If the toner image transferred onto the recording paper P by the secondary transfer unit 37 reaches the nip N of the fixing device 100, the toner adheres to the fixing roll 102 and the pressure roll 104. If the conveyance of the recording paper P is stopped when the paper length size designated in advance is different from the paper length size of the recording paper P currently being conveyed on which the toner image is formed in the image forming apparatus 10. In some cases, the area of the recording paper P on which the toner image is formed remains in the nip portion N. When the recording paper P remaining in the fixing device 100 is pulled out from the discharge portion 16 in this state, the toner is fixed. It adheres to the roll 102 and the pressure roll 104. Further, depending on the toner density, a large amount of toner may be attached to the fixing roll 102 and the pressure roll 104. Therefore, when the recording paper P conveyed next reaches the nip portion N of the fixing device 100, the toner image formed on the recording paper P that has previously entered the fixing device 100 causes the fixing roll 102 and the additional paper to be added. The toner adhering to the pressure roll 104 is contaminated.

  Therefore, in the image forming apparatus 10 according to the present embodiment, when the paper length size of the recording paper P currently being conveyed is not the paper length size designated by the user, the toner attached to the fixing roll 102 and the pressure roll 104 is the next. A stop control process is executed to stop the operation of a predetermined part of the image forming apparatus 10 so as to suppress the adhesion to the recording paper P that is being conveyed.

  Next, the operation of the image forming apparatus 10 when the stop control process is executed will be described with reference to FIG. FIG. 5 is a flowchart showing a flow of processing of a stop control processing program executed by the CPU 150 when the conveyance of the recording paper P from the paper storage unit 12 to the image forming unit 14 is started along with the image forming processing. The stop control processing program is stored in advance in a predetermined area of the ROM 152. Here, in order to avoid complications, the paper length size information is designated in advance by the user via the UI panel 158, and the above-described image forming processing is executed by the image forming apparatus 10 according to the designated paper length size information. A description will be given of the case. Here, a case where the conveyance speed of the recording paper P is a predetermined conveyance speed α will be described in order to avoid complications.

  In step 200 of the figure, reception of the front end detection signal and the rear end detection signal output from the detection unit 91 is waited for, and an affirmative determination is made when both the front end detection signal and the rear end detection signal are received. 202.

  In step 202, it is determined whether or not the paper length size of the recording paper P being conveyed from the paper storage unit 12 to the image forming unit 14 is different from the paper length size designated in advance by the user. Terminates the stop control processing program, and proceeds to step 204 if an affirmative determination is made. In this step 202, the paper length size of the recording paper P is calculated based on the reception interval period of the leading edge detection signal and the trailing edge detection signal output from the detection unit 91 and the conveyance speed α, and the calculated paper length size is determined by the user. It is determined whether or not the sheet length size is different from the previously specified sheet length size.

  In step 204, the voltage application unit 90 is controlled so as to stop the voltage application to the secondary transfer unit 37. In response to this, the voltage application unit 90 stops applying the voltage to the secondary transfer unit 37. As a result, adhesion of the toner image on the intermediate transfer belt 64 to the recording paper P at the secondary transfer position is suppressed.

  In the next step 206, the process waits until a predetermined time elapses after the process of step 204 is completed. In this “predetermined time”, the area where the toner image is not secondarily transferred on the recording sheet P currently being conveyed by the processing of step 204 (hereinafter referred to as “non-secondary transfer area”) is nipped. Time required to reach the portion N (in other words, from the end of the processing in step 204 until the end of the region that has entered the nip portion N preceding the non-secondary transfer region passes through the nip portion N) In this embodiment, the time derived by dividing the transport distance from the secondary transfer position to the nip portion N by the transport speed α is applied. The “predetermined time” is not limited to this, and is based on the time obtained by repeatedly performing an experiment for actually measuring the transport time from the secondary transfer position to the nip portion N using the image forming apparatus 10. It is good also as time derived | led-out (for example, the average value of the conveyance time obtained by repeating experiment). In this case, it may be stored in advance in storage means such as the ROM 152 or the NVM 156, and read out and used when executing the processing of step 206.

  As described above, the non-secondary transfer area of the recording paper P reaches the nip portion N when a predetermined time elapses after the processing of step 204 is completed. At this time, step 206 is affirmative and the routine proceeds to step 208. In step 208, the motor 14A is controlled so that the conveyance operation of the recording paper P is stopped. Accordingly, the motor 14A does not generate a driving force, and the conveyance operation of the recording paper P stops accordingly.

  In the next step 210, error information indicating that the paper length size specified in advance and the paper length size of the recording paper P actually conveyed is different is displayed on the UI panel 158 (error display), and then this stop is performed. The control processing program is terminated. In the image forming apparatus 10 according to the present embodiment, an alarm is generated by visually displaying the error information on the UI panel 158 by the process of step 210. However, the present invention is not limited to this. An alarm may be issued by performing an audible display by a sound reproducing device or a permanent visual display by a printer that the paper length size is different from the paper length size of the recording paper P actually conveyed. Further, an alarm may be issued by combining these visual display, audible display, and permanent visual display.

  As described above, in the image forming apparatus 10 according to the present embodiment, even if the paper length size specified in advance is different from the paper length size of the recording paper P actually conveyed, the nip portion N is placed on the recording paper P. Since the area where the toner image is formed does not stay, even if the recording paper P is pulled out from the discharge unit 16 side, the adhesion of the toner image to the fixing roll 102 and the pressure roll 104 is suppressed. Accordingly, the toner that has formed the toner image formed on the recording paper P that has entered the fixing device 100 in advance, that is, the toner that has adhered to the fixing roll 102 and the pressure roll 104 is then conveyed to the fixing device 100. Occurrence of a situation in which the recording paper P that is received is soiled is suppressed.

  In the above-described embodiment, an example in which the recording paper P has already reached the secondary transfer position when the trailing edge of the recording paper P is detected has been described. At the time of detection, the recording paper P does not have to reach the secondary transfer position yet.

  Further, in the above embodiment, in order to avoid complications, the processing using the predetermined time corresponding to the conveyance speed α is executed in the above step 206 with the conveyance speed α of the recording paper P being the conveyance speed α. For example, a plurality of conveyance speeds may be prepared in advance as the conveyance speed of the recording paper P, and a predetermined time used in the process of step 206 may be derived for each of these conveyance speeds. Further, as the predetermined time used in the process of step 206, a time corresponding to each of the plurality of transport speeds may be stored in advance in a storage unit such as the ROM 152 or the NVM 156. For example, when the conveyance speeds α, β, γ, and δ are adopted as the conveyance speed of the recording paper P, the predetermined time used in the processing of step 206 is (the conveyance distance from the secondary transfer position to the nip portion N). ) / (Transport speed α), (transport distance from secondary transfer position to nip N) / (transport speed β), (transport distance from secondary transfer position to nip N) / (transport speed γ), And (transport distance from the secondary transfer position to the nip portion N) / (transport speed δ) may be employed. Further, the time obtained by the above experiment may be stored in advance in storage means such as the ROM 152 or the NVM 156 in association with each of the transport speeds α, β, γ, and δ.

  In the above embodiment, the toner image is secondarily transferred from the intermediate transfer belt 64 to the recording paper P, and the toner image is fixed on the recording paper P. However, the present invention is not limited to this. The toner image formed on the photosensitive drum 62 may be directly transferred and fixed on the recording paper P without using the intermediate transfer belt 64. In this case, control is performed so as to stop the voltage application for transfer used when transferring from the photosensitive drum 62 to the recording paper P, and the recording paper P that has passed the transfer position when the voltage application for transfer is stopped is stopped. Control is performed so that the conveyance of the recording paper P is stopped when the area reaches the nip portion N.

  In the above-described embodiment, the recording paper P and the toner image formed on the recording paper P are sandwiched between the outer peripheral surfaces of the pair of rolls of the fixing roll 102 and the pressure roll 104, and heated and pressed against them. However, at least one of the fixing roll 102 and the pressure roll 104 may be formed of a belt-like member. Thus, the fixing device 100 is rotatably provided so that the recording paper P is conveyed to the discharge unit 16 side, and at least one of heating and pressurization is applied to the recording paper P and the toner image. It is only necessary to include a pair of rotating bodies that fix the toner image on the recording paper P by applying.

  Further, in the above-described embodiment, an example of a case where secondary transfer is performed by applying a voltage to the secondary transfer roll 89 has been described. However, the present invention is not limited thereto, and a voltage is applied to the belt transport roll 82. Alternatively, the belt conveyance roll 82 and the secondary transfer so that a potential difference sufficient for secondary transfer of the toner image on the intermediate transfer belt 64 onto the recording paper P is generated between the belt conveyance roll 82 and the secondary transfer roll 89. A voltage may be applied to at least one of the rolls 89.

  In the above-described embodiment, the development method using the two-component developer has been described as an example. However, the present invention is not limited to this, and any one-component developer mainly including toner may be used. As described above, any developer may be used as long as the developer forms an image by adhering to the recording paper P using electrostatic force.

  In the above-described embodiment, the four-color development of K, Y, M, and C has been described as an example. However, the present invention is not limited to this. For example, in addition to K, Y, M, and C, light magenta and light cyan are added. Alternatively, six-color development or monochrome development may be used.

  In the above-described embodiment, it is determined whether or not the non-secondary transfer area has reached the nip portion N by determining whether or not a predetermined time has elapsed since the completion of the processing of step 204. In the case of the embodiment, the installation space inside the image forming apparatus 10 and the cost constraints can be ignored. For example, a camera that photographs the recording surface of the recording paper P in front of the nip portion N. And the non-secondary transfer area on the recording paper P is identified based on the image information obtained by photographing with this camera, and it is determined whether or not the non-secondary transfer area has reached the nip portion N. May be. In this case, the present invention is not limited to the camera, and an optical sensor for detecting the thickness of the toner image on the recording paper P may be used, and the non-secondary transfer area on the recording paper P and the other areas are used. Any sensor may be used for identification.

  In the above-described embodiment, an example in which the paper length size is designated in advance by the user via the UI panel 158 has been described. However, the present invention is not limited to this. For example, the CPU 150 is transmitted from the terminal device 162. The received paper length size information is received, the paper length size indicated by the received paper length size information is registered in the NVM 156, and the registered paper length size is recorded as the paper length of the recording paper P that is actually conveyed. It is good also as a comparison object with size.

  Further, in the above-described embodiment, an example in which the single image forming unit 91 is provided in the image forming unit 14 has been described, but the installation space inside the image forming apparatus 10 and cost restrictions may be ignored. For example, a plurality of detection units 91 may be provided. In this case, for example, a configuration example in which the two detection units 91 are arranged along the conveyance path 30 on the upstream side of the alignment roll 38 is given. In this case, the paper length size of the recording paper P being conveyed is detected earlier.

  In the above embodiment, the recording paper P is sandwiched between the belt conveyance roll 82 and the secondary transfer roll 89, and a voltage is applied to the secondary transfer unit 37 to apply a potential difference between the belt conveyance roll 82 and the secondary transfer roll 89. As a result, the toner image on the intermediate transfer belt 64 is secondarily transferred onto the recording paper P, and voltage application to the secondary transfer portion 37 is stopped according to the processing of step 204. You may make it weaken the force which pinches | interposes the recording paper P with the roll 82 and the secondary transfer roll 89. FIG. In this case, in this embodiment, since the secondary transfer roll 89 is urged to the belt conveyance roll 82 by the elastic force of the spring, the urging force may be weakened. For example, a sliding mechanism is provided that slides the outer peripheral surface of the secondary transfer roll 89 and the outer peripheral surface of the belt conveyance roll 82 in a contact and separation direction, and the secondary transfer roll 89 is moved by the sliding mechanism. What is necessary is just to move away from. As a result, the amount of toner adhering to the recording paper P at the secondary transfer position becomes smaller. Further, when the recording paper P remaining on the fixing device 100 is pulled out from the discharge unit 16 side, the force for pinching the recording paper P between the fixing roll 102 and the pressure roll 104 may be weakened. In this case, for example, the above-described sliding mechanism is provided on at least one of the fixing roll 102 and the pressure roll 104, and at least one of the rolls is moved by the sliding mechanism so that the outer peripheral surfaces of the rolls are separated from each other. Good. Accordingly, the recording paper P remaining on the fixing device 100 can be easily pulled out from the discharge unit 16 side. Moreover, since the amount of toner adhering to the recording paper P is suppressed, it is effective when the margin portion of the extracted recording paper P is used.

  Further, in the above-described embodiment, the description has been given by taking an example in which the detection unit 91 detects the leading edge and the trailing edge of the recording paper P. However, the present invention is not limited to this, and the recording paper P passes through the alignment roll 38. Alternatively, a sensor for detecting a load applied to the alignment roll 38 may be provided on the alignment roll 38, and the leading edge and the trailing edge of the recording paper P may be detected using the output from the sensor. That is, in this detection method, the load applied to the alignment roll 38 when the front end side in the conveyance direction of the recording paper P enters the alignment roll 38 and when the rear end side in the conveyance direction of the recording paper P is detached from the alignment roll 38. This is a detection method that utilizes the fact that the amount of change in is larger than other areas of the recording paper P.

  In the above embodiment, the stop control processing program is stored in advance in the ROM 152. However, the present invention is not limited to this, and the stop control processing program is executed by a computer such as a CD-ROM, DVD-ROM, or USB (Universal Serial Bus) memory. A form provided in a state stored in a storage medium to be read may be applied, or a form distributed via wired or wireless communication means may be applied.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14A Motor 37 Secondary transfer part 64 Intermediate transfer belt 89 Secondary transfer roll 90 Voltage application part 91 Detection part 100 Fixing apparatus 102 Fixing roll 104 Pressure roll 150 CPU

Claims (6)

A transfer means for transferring the developer image held on the peripheral surface of the image carrier to a recording medium by applying a voltage, and the developer image transferred to the recording medium by the transfer means in contact with the developer image; A conveying means for conveying the recording medium so as to sequentially pass a fixing means for fixing the developer image to the recording medium;
Detection means for detecting the length of the recording medium upstream in the transport direction from the transfer means;
Control is performed so that the voltage is not applied to the transfer means when a length different from a predetermined length is detected by the detection means, and the leading end of the recording medium in the area where the voltage is not applied Control means for controlling the conveying means to stop conveying the recording medium when the side reaches the fixing means;
An image forming apparatus including:   The time from when the control means is controlled so that the voltage is not applied to the transfer means until the conveyance means is controlled so as to stop the conveyance of the recording medium is set to the recording medium by the transfer means. 2. The distance derived from a transfer position at which a developer image is transferred to a fixing position at which the developer image is fixed on the recording medium by the fixing unit, and a time derived based on a conveyance speed of the recording medium. The image forming apparatus described.   3. The image forming apparatus according to claim 1, wherein the position where the leading end side in the transport direction of the area reaches the fixing unit is a position where the fixing unit comes into contact with the developer image transferred to the recording medium.   The fixing unit is rotatably provided so that the recording medium is transported in the transport direction, and the developer sandwiches the recording medium and the developer image formed on the recording medium with each outer peripheral surface. The image forming apparatus according to claim 1, further comprising a pair of rotating bodies that fix the image on the recording medium.   5. The image forming apparatus according to claim 1, further comprising a warning unit that issues a warning when a length different from the predetermined length is detected by the detection unit. Computer
A transfer means for transferring the developer image held on the peripheral surface of the image carrier to a recording medium by applying a voltage, and the developer image transferred to the recording medium by the transfer means in contact with the developer image; Detecting means for detecting the length of the recording medium being conveyed by the conveying means for conveying the recording medium so as to sequentially pass the fixing means for fixing the developer image to the recording medium on the upstream side in the conveying direction from the transfer means. Means for controlling so that the voltage is not applied to the transfer means when a length different from the predetermined length is detected, and the leading end side in the transport direction of the area where the voltage of the recording medium is not applied is A program for functioning as a means for controlling the conveying means to stop conveying the recording medium when it reaches the fixing means.

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