Patent Publication Number: US-10310431-B2

Title: Image forming device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The entire disclosure of Japanese Patent Application No. 2016-051915 filed on Mar. 16, 2016 including description, claims, drawings, and abstract are incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an image forming device. 
     Description of the Related Art 
     Conventionally, an electrophotographic image forming device including an image forming unit that forms a toner image on an image carrying body, and a transfer unit that primarily transfers the toner image on the image carrying body onto an intermediate transfer belt and secondarily transfers the intermediate toner image on the intermediate transfer belt onto a recording medium is known. 
     In the image forming device, a poor image or an internal device failure may occur due to an adhesive adhering to each member (such as a transport roller and a secondary transfer roller) when a recording medium such as a label sheet, in which sheets are laminated via an adhesive layer, is used. 
     Accordingly, a configuration including a removing member that detects adhesion of an adhesive and removes the same, is proposed (for example, refer to JP 2008-266012 A). 
     In addition, an image forming device generally includes various detection sensors that each detect image density or the position of a recording medium (for example, refer to JP 2015-135399 A and JP 2015-158577 A). Therefore, corrections are made using the detection results of these sensors when, for example, a gradient in the image density, positional displacement of an image, a meandering and an inclination of a recording medium occur because of the adhesion of the adhesive. 
     However, a removing member for removing an adhesive and various detection sensors for detecting image density or a position of a recording medium are needed in such an image forming device. As a result, there are a large number of components in such an image forming device. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of such matters, and an object of the invention is to provide an image forming device capable of achieving good image quality and transport stability even with a small number of components. 
     To achieve the abovementioned object, according to an aspect, an image forming device reflecting one aspect of the present invention comprises: an image forming section configured to form an image onto a recording medium in which sheets are laminated via an adhesive layer; a detection unit configured to detect an amount of an adhesive adhered beyond both edges of the recording medium in a width direction orthogonal to a transport direction; and a control unit configured to calculate a correction amount for correcting an image formation condition for the image forming section on the basis of a difference in the amount of the adhesive on both edges of the recording medium in the width direction detected by the detection unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, advantages and features of the present invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, and wherein: 
         FIG. 1  is a functional block diagram illustrating a configuration of control of an image forming device; 
         FIG. 2  is a schematic diagram illustrating a structure of main sections of the image forming device; 
         FIGS. 3A and 3B  are diagrams describing a structure of a detection unit; 
         FIG. 4  is a diagram illustrating installation positions of the detection units; 
         FIG. 5  is a diagram describing a movement of a recording medium moved by a steering mechanism; 
         FIG. 6  is a flowchart illustrating an adhesive removing process; 
         FIG. 7  is a diagram for describing a moving state of the recording medium in the adhesive removing process; 
         FIGS. 8A to 8C  are diagrams for describing the moving state of the recording medium in the adhesive removing process; 
         FIGS. 9A to 9C  are diagrams for describing the moving state of the recording medium in the adhesive removing process; 
         FIG. 10  is a flowchart illustrating correction amount calculation processing; 
         FIG. 11A  is a diagram illustrating one example of an adhesion amount of an adhesive at near and far sides of the recording medium in a secondary transfer roller; 
         FIG. 11B  is a diagram illustrating one example of a correction amount based on  FIG. 11A ; 
         FIGS. 12A and 12B  are diagrams for describing a method of converting the adhesion amount of an adhesive into an image density; 
         FIG. 13A  is a diagram illustrating one example of an adhesion amount of the adhesive at near and far sides of the recording medium in the secondary transfer roller and a pair of paper feeding rollers; 
         FIG. 13B  is a diagram illustrating one example of a correction amount based on  FIG. 13A ; and 
         FIG. 14  is a flowchart illustrating correction amount calculation processing of another aspect. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. 
     First, a configuration of an image forming device in the present embodiment will be described. 
       FIG. 1  is a functional block diagram illustrating a configuration of control of an image forming device  100 .  FIG. 2  is a schematic diagram illustrating a structure of main sections of the image forming device  100 . 
     As illustrated in  FIGS. 1 and 2 , the image forming device  100  includes, for example, a paper feeding unit  10 , an image forming section G, a fixing unit  40 , an operation display unit  50  as a notification unit, a control unit  60 , a memory unit  70 , a detection unit  80 , and a steering mechanism  90 . 
     The paper feeding unit  10  includes a long recording medium P, which is wound into a roll. The recording medium P is, for example, a label sheet in which two sheets are laminated via an adhesive layer, in the present embodiment. The recording medium P is transported by pairs of paper feeding rollers  11 ,  12 , and  13  to a secondary transfer roller  33  mentioned below. 
     Note that the recording medium P may be a sheet-like medium. 
     The image forming section G includes, for example, a transfer unit  30  and image forming units  20 Y,  20 M,  20 C, and  20 K that form an image with respective colored toners of yellow (Y), magenta (M), cyan (C), and black (K). The image is formed, for example, on the basis of an image forming job (hereinafter, simply called “job”), which has been transmitted from an external device. 
     The image forming units  20 Y,  20 M,  20 C, and  20 K for Y, M, C, and K components have similar structures. Note that for convenience of illustration and description, the same signs are used for common structural components. 
     A structure of the image forming unit will be described by using the image forming unit  20 Y. 
     The image forming unit  20 Y includes, for example, an exposure unit  21 , a developing unit  22 , a photoreceptor  23 , and a charging unit  24 . 
     The charging unit  24  negatively charges the surface of the photoconductive photoreceptor  23  uniformly. Each of the exposure units  21  includes, for example, a semiconductor laser and irradiates a part of the corresponding photoreceptor  23 , matching the image of the respective color components, with laser light. Electrostatic latent images of the respective color components are formed on the surfaces of the respective photoreceptors  23 , due to the potential difference with the surroundings. The developing units  22  house developers of the corresponding color components, and form toner images by making the electrostatic latent images visible by adhering the toners of the respective color components onto the surfaces of the photoreceptors  23 . 
     The transfer unit  30  includes, for example, an intermediate transfer belt  31 , primary transfer rollers  32 , a secondary transfer roller  33 , driving rollers  34 , driven rollers  35 , and a belt cleaning unit not illustrated. 
     The intermediate transfer belt  31  includes an endless belt. The intermediate transfer belt  31  is stretched around the driving rollers  34  and the driven rollers  35 . The intermediate transfer belt  31  travels in a direction illustrated by an arrow A at a fixed speed by the rotation of the driving rollers  34 . 
     The toner images of each of the colors are sequentially overlapped on the intermediate transfer belt  31  to be primarily transferred by the intermediate transfer belt  31  being brought into pressure contact with the photoreceptors  23  by the primary transfer rollers  32 . Then, the intermediate toner image primarily transferred onto the intermediate transfer belt  31  is secondarily transferred onto the recording medium P by the intermediate transfer belt  31  being brought into pressure contact with the recording medium P by the secondary transfer roller  33 . 
     The fixing unit  40  fixes the toner image transferred onto the recording medium P. 
     The fixing unit  40  includes, for example, a heating roller  41  and a pressurizing roller  42  for sandwiching the recording medium P therebetween. 
     The heating roller  41  is heated to a predetermined temperature by a heater that is a heat source. 
     The pressurizing roller  42  is pressed against the heating roller  41  by an elastic member not illustrated. Heat and pressure are applied to the recording medium P, onto which the toner image has been transferred, by the recording medium P passing a nip part between the heating roller  41  and the pressurizing roller  42 . The toner image is thereby melted and fixed. 
     The operation display unit  50  includes a display screen. The screen includes a display unit that displays various information on the screen and an operation unit used for various instructions to be input by a user. 
     The control unit  60  includes, for example, a central processing unit (CPU) and a random access memory (RAM). The CPU of the control unit  60  reads various programs such as a system program and a processing program, which are stored in the memory unit  70 , and applies the programs in the RAM. The CPU executes various processing such as image forming processing, an adhesive removing process, and correction amount calculation processing, by following the applied programs. Details of the adhesive removing process and the correction amount calculation processing will be mentioned below. 
     The memory unit  70  includes, for example, a hard disk drive (HDD) or a non-volatile semiconductor memory. 
     The memory unit  70  stores various programs such as the system program and the processing program executed in the control unit  60 , and data necessary for the control unit  60  to execute these programs. The memory unit  70 , for example, stores setting information necessary for the control unit  60  to execute the various processing. 
       FIGS. 3A and 3B  are diagrams describing a structure of the detection unit  80 . 
     The detection unit  80  includes, for example, two sensors  81  placed at the corresponding edges on both sides of the recording medium P in the width direction (X direction) that is orthogonal to the transport direction, as illustrated in  FIG. 3A . 
     The two sensors  81  are, for example, optical sensors. The two sensors  81  each detect an amount of an adhesive adhered (amount of adhesive) on a roller, beyond both edges of the recording medium P in the X direction. The roller is the target member to be detected (the pairs of paper feeding rollers  11 ,  12 , and  13 , the secondary transfer roller  33 , and the pressurizing roller  42 ). The amount of the adhesive is detected at the nip part of the roller by control from the control unit  60  on the basis of output values of the two sensors  81 . 
     The two sensors  81  include a moving mechanism that moves the two sensors  81  in the X direction. The positions of the two sensors  81  in the X direction are adjusted according to the size of the recording medium P in the X direction. 
     In addition, the detection unit  80  may include, for example, one long line sensor  82  extending along the X direction of the recording medium P, as illustrated in  FIG. 3B . In this case, the part of the line sensor  82  to be used is selected according to the size of the recording medium P in the X direction. 
     In addition, the detection unit  80  can include a camera for capturing an image, instead of the two sensors  81  or the line sensor  82 . In this case, the area of the adhesive is calculated by image analysis, and the amount of the adhesive can be detected from the area. 
       FIG. 4  is a diagram illustrating installation positions of the detection units  80 . 
     The detection units  80  are placed at multiple places on a transport route of the recording medium P, as illustrated in FIG.  2 . The detection units  80  are placed with respect to, for example, the pairs of paper feeding rollers  11 ,  12 , and  13 , the secondary transfer roller  33 , and the pressurizing roller  42 . 
     In addition, the detection units  80  are placed at positions where the detection units  80  can directly detect parts to which the adhesive adheres on the rollers that are the target members to be detected (the pairs of paper feeding rollers  11 ,  12 , and  13 , the secondary transfer roller  33 , and the pressurizing roller  42 ). 
       FIG. 5  is a diagram describing a movement of the recording medium P moved by the steering mechanism  90 . 
     The steering mechanisms  90  are placed at positions corresponding to the detection units  80  placed with respect to the pairs of paper feeding rollers  11 ,  12 , and  13 , and the pressurizing roller  42 . 
     The steering mechanism  90  moves the recording medium P being transported in the X direction by the control from the control unit  60  as illustrated in  FIG. 5 . The recording medium P is moved on the basis of the amount of the adhesive detected by the detection unit  80 . Therefore, the recording medium P can wipe the adhesive adhered on the transport path. 
     The steering mechanism  90  as a mechanism includes, for example, a screen part  91  placed at the edge of the recording medium P in the X direction, and a driving unit  92  that moves the screen part  91  in the X direction. A configuration in which the recording medium P is pushed in the X direction by moving the screen part  91  in the X direction by driving the driving unit  92 , can be adopted. However, the mechanism can be any known mechanism other than this one. 
     Next, an operation of the image forming device  100  in the present embodiment will be described. 
     The image forming device  100  executes the adhesive removing process for removing the adhesive adhered on the transport path, during the image forming processing in the present embodiment. In the adhesive removing process, the recording medium P being transported is moved in the X direction by each of the steering mechanisms  90  on the basis of the amount of the adhesive detected by each of the detection units  80 , thereby allowing the adhesive to be removed. 
     In addition, the image forming device  100  executes the correction amount calculation processing to calculate an amount for correcting an image density on the basis of the amount of the adhesive detected by all of the detection units  80 . 
       FIG. 6  is a flowchart illustrating the adhesive removing process. 
     Also,  FIGS. 7 to 9C  are diagrams for describing the moving state of the recording medium P in the adhesive removing process.  FIGS. 7 to 9C  illustrate the position of the recording medium P in the lateral direction and the amount of the adhesive in the vertical direction, and describe the moving state of the recording medium P corresponding to the amount of the adhesive. Also, X 1  denotes a reference position (position before moving) of a near side and X 2  denotes a reference position (position before moving) of a far side of the recording medium P in the X direction. 
     Note that the adhesive removing process is performed at each steering mechanism  90  while the recording medium P is transported from the paper feeding unit  10  to the fixing unit  40  for the image forming processing. 
     First, the control unit  60  detects the amount of the adhesive by using the detection unit  80  (step S 101 ). To be specific, the control unit  60  detects, by using the detection unit  80 , the amount of the adhesive adhered on a roller, which is the target to be detected, beyond the recording medium P in both edges of the recording medium P in the X direction. 
     Next, the control unit  60  determines whether the amount is a predetermined first threshold or more (step S 102 ). If the amount is below the first threshold (NO in step S 102 ), the control unit  60  repeats the processing of step S 102 . 
     The first threshold is a value that represents a reference of the amount of the adhesive, for the steering to be performed. 
     On the other hand, if the amount is the first threshold or more (YES in step S 102 ), the control unit  60  determines whether the amount is a predetermined second threshold or more, which is larger than the first threshold (step S 103 ). 
     The second threshold is considered to be a reference value indicating that the removing of the adhesive by the steering is impossible. That is to say, the second threshold indicates that the amount of the adhesive is too much and the adhesive cannot be removed simply by being wiped by the recording medium P. 
     When the amount is the second threshold or more (refer to  FIG. 7 ) (YES in step S 103 ), the control unit  60  instructs a user to clean (step S 104 ) and finishes this processing. 
     The cleaning instruction for the user is achieved by, for example, a message being displayed on the display screen of the operation display unit  50 . 
     On the other hand, if the amount is below the second threshold (refer to  FIG. 8A ) (NO in step S 103 ), the control unit  60  performs the steering to move the recording medium P to the side where the adhesive in an amount of the first threshold or more is adhered (refer to  FIG. 8B ) (step S 105 ). 
     As a result, the part shifted from the reference position of the recording medium P wipes the adhesive present in the transport direction (broken line in  FIG. 8B ), whereby the adhesive is removed. 
     Next, the control unit  60  determines whether a predetermined time has passed after the steering (step S 106 ). When the predetermined time has passed (YES in step S 106 ), the control unit  60  makes the recording medium P return to the original position (refer to  FIG. 8C ) (step S 107 ). Thereafter, the control unit  60  returns to step S 101  mentioned above and repeats the process after step S 101 . 
     On the other hand, when the predetermined time has not passed (NO in step S 106 ), the control unit  60  determines whether the recording medium P has moved a fixed distance or more in the same direction, i.e., reached a limit position where the steering is possible (step S 108 ). 
     When the recording medium P has not reached the limit position (refer to  FIG. 9A ) (NO in step S 108 ), the control unit  60  returns to step S 105  mentioned above and repeats the process after step S 105  (refer to  FIG. 9B ). 
     On the other hand, when the recording medium P has reached the limit position (refer to  FIG. 9C ) (YES in step S 108 ), the control unit  60  changes the pressure of the roller that is the target to be detected (step S 109 ), and finishes this processing. 
     Note that step S 109  mentioned above has been described with an example of the configuration in which the pressure of the roller that is the target to be detected changes. However, a cleaning instruction may be given to a user, instead. 
     As mentioned above, in the present embodiment, the recording medium P transported in the image forming processing wipes the adhesive by being steered by each of the steering mechanisms  90  placed with respect to the pairs of paper feeding rollers  11 ,  12 , and  13  and the pressurizing roller  42  by the adhesive removing process being performed. 
     Note that the adhesive will be adhered on the recording medium P by the process. However, this does not cause any effect since the adhesive will be adhered on the edges of the recording medium P. 
       FIG. 10  is a flowchart illustrating the correction amount calculation processing. 
     The correction amount calculation processing is performed after one recording medium P is transported from the paper feeding unit  10  to the fixing unit  40  for the image forming processing, and the amount of the adhesive on both edges of the one recording medium P is detected by all of the detection units  80 . 
     First, the control unit  60  calculates the difference in the amount of the adhesive between the near side and the far side in the X direction at each of the rollers corresponding to the detection units  80  from the detection result at each of the detection units  80  (step S 201 ). 
     Next, the control unit  60  determines whether the difference is in the same direction at all of the rollers (step S 202 ). 
     To be specific, the control unit  60  determines whether there is a directional tendency in which there is a large amount of adhesive at the near side compared with the far side in the X direction, or vice versa, at all of the rollers. 
     The determination is processing for estimating where the cause of the difference in the amount of the adhesive is. The condition of the adhesive applied onto the recording medium P or environment outside the device is considered to be the cause when there is a difference in the same direction at all of the rollers. 
     The roller with the difference is considered to be the cause when the difference is not in the same direction. 
     Note that the determination made here is as to whether there is a difference in the same direction at all of the rollers. However, determination may be made as to whether there is a difference in the same direction at a predetermined number of rollers among all of the rollers. 
     When the difference is not in the same direction (NO instep S 202 ), the control unit  60  calculates the correction amount from the difference in the amount of the adhesive detected at the detection unit  80  placed for the secondary transfer roller  33  (step S 203 ). 
       FIG. 11A  is a diagram illustrating one example of the amount of the adhesive adhered at the near and far sides of the recording medium P detected at the detection unit  80  placed for the secondary transfer roller  33 .  FIG. 11B  is a diagram illustrating one example of the correction amount of the image density at the near and far sides of the recording medium P based on  FIG. 11A . 
     In  FIG. 11A , the amount of the adhesive is larger by W 1  at the far side than at the near side of the recording medium P. In other words, W 1  is the difference in the amount of the adhesive. 
     In this case, as illustrated in  FIG. 11B , the pressure of the secondary transfer roller  33  corresponding to the far side of the recording medium P is considered to be the cause of the difference in the amount of the adhesive. Here, the difference W 1  in the amount of the adhesive is converted into the image density and the correction amount is calculated. 
       FIGS. 12A and 12B  are diagrams for describing a method of converting the difference W 1  in the amount of the adhesive into the image density. 
     First, the amount of the adhesive (the difference W 1  in the amount of the adhesive) is converted into a roller pressure by using conversion data in  FIG. 12A . Next, the roller pressure is converted into the image density by using the conversion data in  FIG. 12A . 
     The conversion data illustrated in  FIGS. 12A and 12B  are stored beforehand in the memory unit  70  as setting information. 
     When there is the difference in the same direction (YES in step S 202 ) in  FIG. 10 , the control unit  60  calculates the correction amount of the image density by subtracting the amount of the adhesive detected at the detection units  80  placed for the pairs of paper feeding rollers  11 ,  12 , and  13  from the amount of the adhesive detected at the detection unit  80  placed for the secondary transfer roller  33  (step S 204 ). 
       FIG. 13A  is a diagram illustrating one example of the amount of the adhesive adhered at the near and far sides of the recording medium P detected at the detection units  80  placed for the secondary transfer roller  33  and the pair of paper feeding rollers  11 .  FIG. 13B  is a diagram illustrating one example of the correction amount of the image density at the near and far sides of the recording medium P based on  FIG. 13A . 
     In  FIG. 13A , the amount of the adhesive is larger by W 2  at the far side than at the near side of the recording medium P at the detection unit  80  placed for the secondary transfer roller  33 . In other words, W 2  is the difference in the amount of the adhesive. 
     The amount of the adhesive is larger by W 3  at the far side than at the near side of the recording medium P at the detection unit  80  placed for the pair of paper feeding rollers  11 . In other words, W 3  is the difference in the amount of the adhesive. 
     In this case, the difference W 2  in the amount of the adhesive in the secondary transfer roller  33  is divided by the difference W 3  in the amount of the adhesive in the pair of paper feeding rollers  11 . The resultant value is the amount of the adhesive causing a substantial effect on the secondary transfer roller  33  (substantial amount of adhesive W 4 ). Accordingly, the substantial amount of the adhesive W 4  is converted into the image density and the correction amount is calculated. 
     Note that the calculation of the substantial amount of the adhesive W 4  by using the difference in the amount of the adhesive at the pair of paper feeding rollers  11  (the difference W 3  in the amount of the adhesive) has been described. However, it is preferable, in view of accuracy, to use an average value of the amounts of the adhesive detected at the pairs of paper feeding rollers  11 ,  12 , and  13 , for the calculation of the substantial amount of the adhesive W 4 . 
     Note that as a method of converting the substantial amount of the adhesive W 4  into the image density,  FIGS. 12A and 12B  mentioned above can be used similarly to step S 203  mentioned above. 
     Next, the control unit  60  determines whether processing of steps S 201  to S 204  mentioned above has been repeated a predetermined number of times, in other words, whether the correction amount has been calculated for a predetermined number of the recording media P (step S 205 ). When the predetermined number of times is not satisfied (NO in step S 205 ), the control unit  60  returns to step S 201  mentioned above and repeats the processing after step S 201 . 
     On the other hand, when the processing is repeated the predetermined number of times (YES in step S 205 ), the control unit  60  determines a final correction amount, which is an average value of the predetermined number of the correction amounts (step S 206 ). 
     Thereafter, the control unit  60  performs correction processing of the image density, for example, exposure amount control and density gradation control by using the final correction amount. 
     The correction amount is calculated on the basis of the difference in the amount of the adhesive, and the image density is corrected as mentioned above in the present embodiment. 
     In the present embodiment, as mentioned above, the image forming device includes the image forming section G configured to form an image onto the recording medium P in which sheets are laminated via an adhesive layer, the detection unit  80  configured to detect an amount of an adhesive adhered beyond both edges of the recording medium P in the X direction, and the control unit  60  configured to calculate a correction amount for correcting an image formation condition for the image forming section G on the basis of a difference in the amount of the adhesive between both edges of the recording medium P in the X direction detected by the detection unit  80 . 
     Therefore, there is no need to install various sensors, and good image quality and transport stability can be achieved with a small number of components. 
     In addition, in the present embodiment, the image forming device includes the paper feeding unit  10  configured to feed the recording medium P to the image forming section G, the detection units  80  are included in the image forming section G and the paper feeding unit  10 , and the control unit  60  calculates the correction amount by subtracting an amount of an adhesive detected by the detection unit  80  included in the paper feeding unit  10  from an amount of an adhesive detected by the detection unit  80  included in the image forming section G when all of the detection units  80  at the image forming section G and the paper feeding unit  10  detect a larger amount of an adhesive at an edge on the same side of the recording medium P in the X direction. 
     Therefore, the correction amount can be calculated more accurately because the amount of the adhesive adhered beyond the recording medium P (amount of adhesive) caused from the environment is subtracted. 
     In addition, in the present embodiment, the paper feeding unit  10  includes the plurality of detection units  80 , and the control unit  60  calculates the correction amount by subtracting an average value of amounts of an adhesive detected by the detection units  80  in the paper feeding unit  10  from an amount of an adhesive detected by the detection unit  80  included in the image forming section G. 
     Therefore, the amount of the adhesive adhered beyond the recording medium P (amount of adhesive) caused from the environment can be calculated accurately. 
     In addition, in the present embodiment, the control unit  60  calculates the correction amount for a plurality of the recording media P and determines, as a final correction amount, an average value of the correction amounts calculated for the plurality of recording media P. 
     Therefore, the image formation condition for the image forming section G can be more accurately corrected. 
     In addition, in the present embodiment, the detection unit  80  includes the line sensor  82  extending in the X direction of the recording medium P. 
     Therefore, recording media P in various sizes can be used without including a plurality of sensors or a mechanism that moves the sensors. 
     In addition, in the present embodiment, the detection unit  80  is placed at a position where the detection unit  80  can detect a part of the target member to be detected (the pairs of paper feeding rollers  11 ,  12 , and  13 , the secondary transfer roller  33 , and the pressurizing roller  42 ) to which the adhesive is adhered beyond both edges of the recording medium P in the X direction. 
     Therefore, the amount of the adhesive can be detected more accurately by the detection unit directly detecting the part of the target member to be detected to which the adhesive is adhered. 
     In addition, in the present embodiment, the image forming device further includes the steering mechanism  90  configured to move the recording medium P in the X direction, and the control unit  60  moves the recording medium P in a direction in which an amount of an adhesive exceeds a first threshold, by the steering mechanism  90  when the amount of the adhesive detected by the detection unit  80  exceeds the first threshold. 
     Therefore, the recording medium P being transported can wipe the adhesive. 
     In addition, in the present embodiment, the control unit  60  makes the recording medium P return to an original position by the steering mechanism  90  when a predetermined time has passed since the recording medium P has been moved. 
     Therefore, the control unit can prevent the recording medium P from excessively deviating in the X direction. 
     In addition, in the present embodiment, the image forming device further includes the pairs of rollers (pairs of paper feeding rollers  11 ,  12 , and  13 , the secondary transfer roller  33 , and the pressurizing roller  42 ) configured to sandwich the recording medium P therebetween and transport the recording medium P, the detection units  80  are placed with respect to the pairs of rollers, and the control unit  60  changes a nip pressure of the pairs of rollers when the recording medium P is moved for a fixed distance or more in the same direction by the steering mechanism  90 . 
     Therefore, it is possible to prevent a large amount of the adhesive from adhering beyond the recording medium P on one side thereof in the X direction by changing the nip pressure of the pair of rollers. 
     In addition, in the present embodiment, the image forming device further includes the operation display unit  50  configured to notify a user of a predetermined message, and the control unit  60  prompts the user to clean by using the operation display unit  50  when the recording medium P is moved for a fixed distance or more in the same direction by the steering mechanism  90 . 
     Therefore, the operation display unit  50  can notify the user that a large amount of the adhesive is adhered on one side of the recording medium P in the X direction, and prompt the user to clean. 
     In addition, in the present embodiment, the image forming device further includes the operation display unit  50  configured to notify a user of a predetermined message, and the control unit  60  prompts the user to clean by using the operation display unit  50  when an amount of an adhesive detected by the detection unit  80  exceeds the second threshold larger than the first threshold. 
     Therefore, the operation display unit  50  can notify the user that a large amount of the adhesive is adhered on one side of the recording medium P in the X direction, and prompt the user to clean. 
     Note that the processing of steps S 201  to S 204  mentioned above is repeated a predetermined number of times and the final correction amount is determined by use of an average, i.e., the average of the correction amounts of the predetermined number in the flowchart in  FIG. 10  mentioned above. However, the configuration may not repeat the processing of steps S 201  to S 204  mentioned above a predetermined number of times as illustrated in the flowchart in  FIG. 14 . 
     In  FIG. 14 , the same processing as  FIG. 10  is executed from steps S 201  to S 204 . 
     Thereafter, the control unit  60  detects the density of an image formed on the recording medium P by a density sensor (not illustrated) placed downstream of the secondary transfer roller  33 , compares the result with the correction amount calculated at step S 203  or S 204  mentioned above, and determines a final correction amount (step S 207 ). 
     With this configuration, a correction accuracy can be ensured without repeating the processing of steps S 201  to S 204  mentioned above a predetermined number of times. 
     Note that in view of further increasing the accuracy, the processing of steps S 201  to S 204  mentioned above is repeated a predetermined number of times in the flowchart in  FIG. 10  mentioned above and the final correction amount is determined by use of the result of the density sensor in the flowchart in  FIG. 14  mentioned above. However, it is possible to omit any of these. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustrated and example only and is not to be taken by way of limitation, the scope of the present invention being interpreted by terms of the appended claims.