JP6201719B2 - Paper shape measuring apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a paper shape measuring apparatus capable of accurately measuring a curved shape of a paper and an image forming apparatus including the paper shape measuring apparatus. More specifically, the present invention relates to a paper shape measuring device capable of measuring the shape of a paper being conveyed while conveying the paper, and an image forming apparatus including the paper shape measuring device.

  In a general image forming apparatus using an electrophotographic method such as a printer or a copying machine, a process for fixing a toner image transferred onto a sheet is performed. In the fixing process, the paper carrying the toner image is pressurized while being heated. The sheet after the fixing process may be curled due to curling or undulation. When the paper is curled or the like, the paper is hindered on the paper discharge tray. In addition, when binding a plurality of sheets, binding quality may be deteriorated due to curling or the like. Therefore, it is preferable that curling and undulation of the discharged paper is reduced as much as possible.

  Therefore, in order to reduce curl and the like, a decurling device that appropriately feeds back the heating temperature in the fixing processing unit and corrects for removing the curl and the like is provided. The feedback to the heating temperature of the fixing processing unit and the adjustment of the curl correction amount in the decurling device are both performed based on the measured curl degree by measuring the shape of the paper after the fixing process. For this reason, it is necessary to accurately measure the shape of the paper. For example, when a sheet is conveyed while being sandwiched between a pair of conveyance rollers, the sheet is constrained by the pair of conveyance rollers, and thus has a shape different from the actual shape. Therefore, it is preferable to measure the shape of the paper in a state where the paper is not constrained by a pair of transport rollers or the like.

  An example of a technique for measuring the shape of a sheet that is not restrained is Patent Document 1. That is, Patent Document 1 describes a method for measuring the shape of a paper sheet by taking an image of the paper sheet placed on an inspection device provided obliquely with a video camera from above.

JP-A-8-313219

  By the way, as a paper shape measuring method, for example, there are a lattice projection method and a light cutting method. The lattice projection method is a method of measuring the shape of a sheet by irradiating the entire surface of the sheet with a lattice-shaped laser beam and imaging the entire surface of the sheet during irradiation. In the optical cutting method, a slit-shaped laser beam in a direction perpendicular to the paper transport direction is irradiated and the paper is passed through the irradiation position. This is a method of measuring the paper shape by taking images once.

  From the viewpoint of the measurement method, it is preferable to select the light cutting method rather than the lattice projection method. This is because, in contrast to the grating projection method that requires an expensive laser irradiation part to irradiate the lattice-shaped laser light, the laser irradiation part is inexpensive in the light cutting method that requires only one slit-shaped laser light irradiation. . Further, in the lattice projection method, since the entire surface of the sheet is imaged at a time, the imaging unit must be arranged at a position far from the sheet. On the other hand, in the optical cutting method, since it is not necessary to image the entire surface of the paper at a time, the imaging unit can be arranged at a position close to the paper. This is because the configuration near the imaging unit can be reduced in size.

  For this reason, for example, as in the above-described prior art, the laser beam irradiation position is provided on the plate surface of the inclined plate provided obliquely, and the paper is slid through the irradiation position and restrained. It is possible to measure the shape of the sheet in the absence of the sheet by the optical cutting method. However, in such a configuration, in order to accurately measure the paper shape, the distance from the upstream conveying roller pair that feeds the paper onto the inclined plate to the irradiation position is the length in the paper conveying direction. It must be longer than this.

  This is because when the leading edge of the sheet reaches the irradiation position, if the trailing edge of the sheet is sandwiched between the upstream conveying roller pair, the accurate shape on the leading edge side may not be measured. Further, the distance from the irradiation position to the pair of rollers on the downstream side that carries the sheet passing through the inclined plate from the inclined plate must be made longer than the length in the sheet conveying direction. That is, when trying to accurately measure the paper shape by the optical cutting method, there is a problem that the apparatus becomes longer in the paper transport direction.

  The present invention has been made for the purpose of solving the problems of the prior art described above. That is, an object of the present invention is to provide a paper shape measuring apparatus and an image forming apparatus that are capable of measuring the paper shape accurately while being inexpensive and small.

  The paper shape measuring device of the present invention made for the purpose of solving this problem is a paper shape measuring device for measuring the curved shape of a paper at the measurement position while passing the paper through the measurement position. It is provided at a distance within the length of the transport direction from the measurement position to at least one of the transport section that carries and transports it to the measurement position and at least one of the upstream and downstream of the measurement position in the transport section. A restraining member that takes a restraint state that restrains the part and a non-restraint state that releases the restraint state, an imaging unit that captures an image when a measurement target region that is at least a part of the measurement position passes through the measurement position , An irradiation unit that irradiates light to a part of the area in the paper conveyance direction at the measurement position, and the restraining member is configured such that when at least a part of the measurement target area of the paper passes through the measurement position, Taking the constraint condition, when not take unconstrained is a sheet shape measuring apparatus, characterized in that taking the constraint condition.

  The paper shape measuring apparatus of the present invention measures the paper shape by an optical cutting method using an irradiation unit that emits slit light. For this reason, the irradiation unit is inexpensive, and the imaging unit can be arranged at a position close to the measurement position to reduce the size of the apparatus. Further, when the measurement target area of the sheet passes through the measurement position, the restraining member can be in an unconstrained state. Therefore, it is possible to accurately measure the shape of the sheet that is not deformed due to restraint on the carrying surface of the transport unit, and the length of the transport unit in the transport direction can be short.

  Further, in the paper shape measuring apparatus described above, the transport unit rotates the belt member in a direction in which the upper surface moves in the paper transport direction, with the upper surface of the outer peripheral surface of the endless belt member as a support surface. An upstream conveying roller pair that is provided upstream of the belt conveying unit and can be pressed or separated toward the other at least one of the belt conveying units. The pair takes a pressure contact state in a restrained state and takes a separated state in an unrestrained state, and takes a pressure contact state until the leading edge of the paper being conveyed reaches the upstream transport roller pair. When the tip of the measurement target area reaches a separation position provided between the upstream conveying roller pair and the measurement position, a separation operation is performed to establish a separation state. Preferred. This is because the sheet can be passed through the measurement position on the belt conveyance unit in an unconstrained state by setting the upstream conveyance roller pair in the separated state.

  Further, in the paper shape measuring apparatus described above, the belt member is formed with a plurality of through holes penetrating in the thickness direction, and is provided inside the belt member as another one of the restraining members. It has an upstream suction part that can suck the air in the upstream suction area upstream from the measurement position on the belt member carrying surface through the through hole of the member, and the upstream suction part is a suction that performs suction in a restrained state. It is in a non-suction state in which suction is not performed in the unconstrained state, and the suction state is taken before the upstream transport roller pair performs the separating operation, and the upstream transport roller pair performs the separating operation, and then the transport is performed. It is preferable that the non-suction state be taken before the leading end of the measurement target area of the paper sheet reaches the measurement position. This is because it is possible to suppress the influence on the paper being transported by the pressure contact of the upstream transport roller pair and the impact due to separation. This is because it can be reliably conveyed from the pair of upstream conveyance rollers onto the carrying surface of the belt conveyance unit.

  Further, in the paper shape measuring apparatus described above, when the upstream suction section is in the suction state, the suction invalidation that invalidates the suction for each divided upstream suction area obtained by dividing the upstream suction area into a plurality of the paper transport directions. Or a suction effective state that does not invalidate the suction, and among the plurality of divided upstream suction areas, at least the divided upstream suction area that does not carry the paper is set to the suction invalid state, It is preferable that the divided upstream suction area not to be in a suction effective state. This is because a sheet whose length in the transport direction is shorter than the upstream suction area can be appropriately held and restrained in the upstream suction area.

  Further, in the paper shape measuring apparatus described above, the transport unit rotates the belt member in a direction in which the upper surface moves in the paper transport direction, with the upper surface of the outer peripheral surface of the endless belt member as a support surface. A belt conveying section that has a pair of downstream conveying rollers that are provided downstream of the belt conveying section and can be pressed against or separated from each other toward the other; The pair takes a pressure contact state in the restrained state and takes a separated state in the non-restrained state, and takes a separated state until the leading edge of the paper reaches the downstream transport roller pair. When the rear end of the measurement target area reaches the pressure contact position provided between the measurement position and the pair of downstream transport rollers, a pressure contact operation is performed to establish a pressure contact state. Preferred. This is because after passing the measurement position on the belt conveyance unit in an unconstrained state, the sheet can be constrained by the downstream conveyance roller pair in a pressure contact state.

  Further, in the paper shape measuring apparatus described above, the belt member is formed with a plurality of through holes penetrating in the thickness direction, and is provided inside the belt member as another one of the restraining members. It has a downstream suction part that can suck the air in the downstream suction area downstream from the measurement position on the belt member carrying surface through the through hole of the member, and the downstream suction part is a suction that performs suction in a restrained state. In the non-restrained state, the suction is not performed, and the suction state is taken before the downstream transport roller pair performs the pressure contact operation, and after the downstream transport roller pair performs the pressure contact operation, It is preferable that the non-suction state be taken before the leading edge of the paper reaches the downstream suction portion. This is because it is possible to suppress the influence on the paper being conveyed due to the impact by the pressure contact and separation of the downstream conveyance roller pair. This is because the belt can be reliably conveyed from the carrying surface of the belt conveyance unit to the downstream conveyance roller pair.

  Further, in the paper shape measuring apparatus described above, when the downstream suction unit is in the suction state, the suction invalidation that invalidates the suction for each divided downstream suction region obtained by dividing the downstream suction region into a plurality of the paper transport directions. Or a suction effective state that does not invalidate the suction. Among the plurality of divided downstream suction regions, at least the divided downstream suction region that does not carry the paper is set to the suction invalid state, and the suction invalid state is set. It is preferable that the divided downstream suction region not to be in a suction effective state. This is because even a sheet whose length in the transport direction is shorter than the downstream suction area can be appropriately held and restrained in the downstream suction area.

  According to another aspect of the present invention, there is provided an image forming apparatus having an image forming unit that transfers a toner image onto a sheet and a fixing unit that performs a fixing process of the transferred toner image on the sheet. However, the paper shape measuring apparatus extends to the image forming apparatus characterized in that it is provided downstream of both the image forming unit and the fixing unit in the paper transport direction.

  According to the present invention, there is provided a paper shape measuring apparatus and an image forming apparatus which are small in size and capable of accurately measuring the paper shape.

1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. FIG. 2 is a diagram illustrating an outline of a control configuration of an image forming apparatus according to the present embodiment. It is a schematic block diagram of the reading conveyance apparatus which concerns on a 1st form. It is a figure for demonstrating the timing of the press-contact and separation | spacing of a belt front roller pair and a belt rear roller pair. It is a schematic block diagram of the reading conveyance apparatus which concerns on a 2nd form. It is a top view of the conveyance belt which concerns on a 2nd form. It is a figure for demonstrating the relationship of the timing of the suction by a duct, and the timing of the press-contact and separation | spacing in a belt front roller pair and a belt rear roller pair. It is a schematic block diagram of the reading conveyance apparatus which concerns on a 3rd form. It is a figure for demonstrating the opening / closing timing of the shutter of a duct.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In this embodiment, the present invention is embodied in an electrophotographic printer.

[First embodiment]
FIG. 1 shows a schematic configuration of an image forming apparatus 1 according to the first embodiment. The image forming apparatus 1 includes an image forming unit 2, a fixing processing unit 3, and a correction unit 4. The image forming unit 2 forms a toner image and transfers the formed toner image onto the paper P. The fixing processing unit 3 fixes the toner image on the paper P by heating and pressurizing the paper P carrying the toner image. The correction unit 4 removes curling and undulation of the paper P after the fixing process.

  First, the image forming unit 2 will be described. The image forming apparatus 1 is a so-called tandem color printer having an intermediate transfer belt 30 in the image forming unit 2. The intermediate transfer belt 30 is an endless belt member having conductivity, and both ends in the figure are supported by rollers 31 and 32. At the time of image formation, the roller 31 on the right side in FIG. 1 is driven to rotate counterclockwise. As a result, the intermediate transfer belt 30 and the left roller 32 in FIG. 1 are driven to rotate.

  A secondary transfer roller 40 is provided on the outer peripheral surface of the portion of the intermediate transfer belt 30 supported by the right roller 31 in FIG. The secondary transfer roller 40 and the outer peripheral surface of the intermediate transfer belt 30 are in contact with each other, and a secondary transfer region is formed by the contact transfer nip N1.

  Also, a belt cleaner 41 is provided on the outer peripheral surface of the portion of the intermediate transfer belt 30 supported by the left roller 32 in FIG. The belt cleaner 41 is in pressure contact with the outer peripheral surface of the intermediate transfer belt 30, and a collection area 42 for collecting the transfer residual toner is formed by the contacting portion.

  In the lower part of the intermediate transfer belt 30 in FIG. 1, image forming units 10Y, 10M, 10C for yellow (Y), magenta (M), cyan (C), and black (K) are sequentially arranged from left to right. 10K is arranged. The image forming units 10Y, 10M, 10C, and 10K are all for transferring the toner images of the respective colors onto the intermediate transfer belt 30. The image forming units 10Y, 10M, 10C, and 10K all have the same configuration. For this reason, in FIG. 1, the image forming unit 10 </ b> Y is represented by a reference numeral.

  That is, the image forming units 10Y, 10M, 10C, and 10K include a photosensitive member 11 that is a cylindrical electrostatic latent image carrier, a charger 12, a developing unit 14, and a photosensitive member cleaner 16 disposed around the photosensitive member. have. A primary transfer roller 15 is disposed at a position facing the photoconductor 11 with the intermediate transfer belt 30 therebetween. Further, an exposure device 13 is disposed below the image forming units 10Y, 10M, 10C, and 10K for each color in FIG.

  The charger 12 is for uniformly charging the surface of the photoconductor 11. The exposure device 13 is for irradiating the surface of the photoconductor 11 with laser light based on image data to form an electrostatic latent image. The developing unit 14 is for applying toner to the surface of the photoreceptor 11 by the developing roller 17.

  Above the intermediate transfer belt 30 in FIG. 1, hoppers 18Y, 18M, 18C, and 18K are arranged. The hoppers 18Y, 18M, 18C, and 18K are equipped with toner bottles 19Y, 19M, 19C, and 19K that store toner of the corresponding color, respectively. Each hopper 18 is connected to the developing unit 14 of the image forming unit 10 of the corresponding color. The hopper 18 is for appropriately supplying toner contained in the toner bottle 19 to the corresponding developing unit 14.

  A density sensor for detecting the image density of the toner image transferred onto the intermediate transfer belt 30 is located downstream of the image forming unit 10K in the rotation direction of the intermediate transfer belt 30 and upstream of the transfer nip N1. 20 is provided. The density sensor 20 uses the outer peripheral surface of the intermediate transfer belt 30 as a detection position. The density sensor 20 includes, for example, a light projecting unit that irradiates light toward a detection position and a light receiving unit that receives the reflected light, which are used for adjusting the image density.

  In FIG. 1, the charger 12 is a roller charging type having a roller shape, but the present invention is not limited to this. A corona discharge charging charger, a blade charging member, a brush charging member, or the like may be used. Further, although the photosensitive member cleaner 16 is a plate and has one end portion in contact with the outer peripheral surface of the photosensitive member 11, the present invention is not limited to this. Other cleaning members, for example, a fixed brush, a rotating brush, a roller, or a combination of a plurality of them can be used. Alternatively, if a cleaner-less system in which the untransferred toner on the photoconductor 11 is collected by the developing unit 14 is employed, the photoconductor cleaner 16 may be omitted.

  A detachable paper feed cassette 51 is mounted at the lower part of the image forming apparatus 1. A conveyance path 50 is provided above the right side in FIG. Then, the sheets P stored in the sheet feeding cassette 51 by stacking are sent out one by one from the uppermost one to the conveying path 50 by the sheet feeding roller 52.

  A pair of registration rollers 53 and a transfer nip N1 are arranged in this order on the conveyance path 50 of the paper P in the image forming unit 2 sent out by the paper feed roller 52. The registration roller 53 is for adjusting the timing of feeding the paper P to the transfer nip N1. Further, the toner image on the intermediate transfer belt 30 is transferred to the paper P at the transfer nip N1. A fixing processing unit 3 is provided further downstream of the transfer nip N1 in the conveyance path 50.

  The fixing processing section 3 is for performing a fixing process on the paper P of the toner image transferred from the intermediate transfer belt 30 to the paper P in the transfer nip N1. The fixing processing unit 3 is provided with a heating roller 60 and a pressure roller 61 facing the heating roller 60 with the conveyance path 50 interposed therebetween. The heating roller 60 has a heater 62 inside. The pressure roller 61 is pressed against the heating roller 60 in a direction perpendicular to the axis. Due to the pressure contact, a fixing nip N <b> 2 for fixing the paper P is formed between the heating roller 60 and the pressure roller 61.

  The heating roller 60 is driven to rotate counterclockwise during image formation. The pressure roller 61 is driven and rotated by the rotation of the heating roller 60. The fixing processing unit 3 performs fixing processing of the toner image carried by the paper P by heating and pressurizing the paper P passing through the fixing nip N2. A correction unit 4 is provided further downstream of the fixing nip N <b> 2 of the conveyance path 50. The correction unit 4 is for correcting and removing curls and undulations generated on the paper P. The curling and undulation of the paper P occurs, for example, when the paper P is heated during the fixing process. That is, the degree of moisture evaporation from the paper P during heating is not uniform, and the paper P is curled.

  The correction unit 4 is provided with a reading conveyance device 100, a decurling device 80, and a paper discharge roller 54 along the conveyance path 50. A paper discharge tray 55 is provided at the lower part of the correction unit 4 further downstream of the paper discharge roller 54. The reading and conveying apparatus 100 conveys the paper P as will be described in detail later. In addition, an imaging unit 70 and an irradiation unit 71 are provided above the reading and conveying apparatus 100. The imaging unit 70 and the irradiation unit 71 are for measuring the shape of the paper P being conveyed by the reading and conveying apparatus 100 in a non-contact manner by an optical cutting method.

  The imaging unit 70 is a CCD camera, and reads the shape of the paper P that is being conveyed by the reading and conveying apparatus 100 at the measurement position M. The measurement position M has a length in the depth direction in FIG. Further, although the measurement position M is indicated by a dot in FIG. 1, the measurement position M actually has a certain length in the conveyance direction of the paper P. The same applies to FIG. 3 and subsequent figures.

  As shown in FIG. 1, the irradiation unit 71 irradiates the laser beam L toward the measurement position M from an oblique direction with respect to the paper surface of the paper P. The laser beam L has a slit shape in the width direction (depth direction in FIG. 1) orthogonal to the transport direction of the paper P.

  Then, by irradiation with the laser beam L, a linear line of light in the width direction is formed on the surface of the sheet P at the measurement position M. The imaging unit 70 is disposed immediately above the measurement position M, and can read the shape of the paper P by imaging the linear light streaks formed on the paper P at the measurement position M by the laser light L. . In this embodiment, by measuring the shape of the paper P by the optical cutting method, the imaging unit 70 is arranged at a position closer to the transport path 50 than when performing the grid projection method. Further, since the light cutting method is used, a cheaper laser light source is used for the irradiation unit 71 than in the case of the lattice projection method.

  The decurling device 80 is for correcting curling or the like of the generated paper P when the paper P is curled or wavy. The decurling device 80 has a plurality of decurling rollers 81 that are roller pairs arranged along the transport path 50. Then, the paper P is passed through the correction nip N3 of each decurling roller 81 to correct the curl or the like.

  In the decurling device 80 of this embodiment, the pressure contact force in the correction nip N3 of each decurling roller 81 can be adjusted. By adjusting the pressure contact force, it is possible to adjust the amount of correction and the direction of correction for correcting curling and undulation occurring on the paper P. The correction amount and correction direction in the decurling device 80 are obtained based on the shape of the paper P read by the imaging unit 70.

  Next, an example of a normal image forming operation by the image forming apparatus 1 of this embodiment will be briefly described. The following description is an example of an image forming operation in a print mode in which a color image is formed on the paper P stored in the paper feed cassette 51 using four color toners.

  During normal image formation, the intermediate transfer belt 30 and the photoreceptors 11 of the respective colors are rotated at a predetermined peripheral speed in the directions indicated by arrows in FIG. First, the outer peripheral surface of the photoconductor 11 is charged almost uniformly by the charger 12. Next, light corresponding to the image data is projected onto the outer peripheral surface of the charged photoconductor 11 by the exposure device 13 to form an electrostatic latent image. Subsequently, the electrostatic latent image is developed with toner supplied by the rotation of the developing roller 17 of the developing unit 14, and a toner image is formed on the photoreceptor 11.

  The toner images of the respective colors formed on the photosensitive member 11 are transferred (primary transfer) onto the intermediate transfer belt 30 by the primary transfer roller 15. That is, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30 in this order. The transfer residual toner that is not transferred to the intermediate transfer belt 30 and remains on the photoconductor 11 even after passing the primary transfer roller 15 is scraped off by the photoconductor cleaner 16 and removed from the photoconductor 11. . The superimposed four color toner images are conveyed by the intermediate transfer belt 30 to the transfer nip N1.

  On the other hand, the paper P stored in the paper feed cassette 51 is pulled out from the uppermost one by one to the transport path 50 by the paper feed roller 52. The drawn paper P is conveyed along the conveyance path 50, and reaches the transfer nip N1 by the registration roller 53 in synchronization with the toner image placed on the intermediate transfer belt 30. Then, the superimposed four color toner images are transferred (secondary transfer) onto the paper P in the transfer nip N1. The toner image remaining on the intermediate transfer belt 30 even after passing through the transfer nip N1 is scraped off by the belt cleaner 41 in the collection area 42. As a result, the intermediate transfer belt 30 is removed.

  The paper P on which the toner image has been transferred is further conveyed downstream of the conveyance path 50. That is, the paper P is transported to the correction unit 4 after the fixing processing unit 3 performs the toner image fixing process. Then, in the correction unit 4, the shape of the paper P is read by the imaging unit 70, and correction is performed by the decurling device 80 based on the shape of the paper P, and then the paper is discharged onto the paper discharge tray 55 by the paper discharge roller 54. The

  FIG. 2 shows an outline of the control configuration of the image forming apparatus 1. The image forming apparatus 1 includes a controller unit 90 and an engine control unit 91 in order to control each unit. The engine control unit 91 is configured around a CPU 92 that performs control processing for the entire apparatus.

  For example, the CPU 92 controls various loads 94 to form an image. That is, the toner image is formed in the image forming unit 10 and the temperature of the heater 62 in the fixing processing unit 3 is controlled. Further, in the correction unit 4 at the time of image formation, the amount of correction of the decurling device 80 is controlled based on the control of reading by the imaging unit 70 of the shape of the paper P being conveyed through the reading and conveying device 100 and the shape of the read paper P. And the direction of correction is calculated. Further, the decurling device 80 is controlled so that the calculated correction amount and correction direction are obtained.

  The engine control unit 91 includes a nonvolatile memory 93 attached to the main body and a nonvolatile memory 95 attached to various units. The CPU 92 performs writing and reading of the nonvolatile memory 93 attached to the main body. That is, the nonvolatile memory 93 stores data calculated by the CPU 92 and the like. Further, the non-volatile memory 93 also stores the rotational speed of the roller 31, the rotational speed of each photoconductor 11, the system speed such as the transport speed of the paper P in the transport path 50, and the like.

  Further, the CPU 92 performs writing and reading of the nonvolatile memory 95 attached to various units. In the nonvolatile memory 95 attached to the various units, for example, the remaining amount of toner is stored in the memory attached to the toner bottle 19, and the number of prints is stored in the memory attached to the imaging unit.

  The controller unit 90 is connected to an external personal computer or the like and receives an instruction input. Further, various information such as a dot counter value is exchanged between the engine control unit 91 and the controller unit 90.

  FIG. 3 is a schematic diagram of the reading and conveying apparatus 100 of the present embodiment. As shown in FIG. 3, the reading and conveying apparatus 100 includes a conveying belt 110, a belt front roller pair 130, and a belt rear roller pair 140 as a configuration for conveying the paper P.

  The conveyor belt 110 is an endless belt member, and both ends in the figure are supported by rollers 120 and 121. When the right roller 121 in FIG. 3 is driven to rotate clockwise, the conveyor belt 110 and the left roller 120 in FIG. 3 are driven to rotate. As a result, the paper P carried on the carrying surface which is the upper surface of the outer circumferential surface of the carrying belt 110 can be carried along the carrying path 50 in the right direction in FIG.

  As shown in FIG. 3, the belt front roller pair 130 is a conveyance roller pair including a lower roller 131 and an upper roller 132 provided upstream of the conveyance belt 110. The lower roller 131 is disposed on the lower side of the conveyance path 50, and the upper roller 132 is disposed on the upper side of the conveyance path 50. The lower roller 131 is a driving roller and is driven to rotate clockwise during image formation.

  The upper roller 132 can move up and down as indicated by arrows in FIG. That is, the upper roller 132 moves upward in FIG. 3 and can be separated from the lower roller 131. The state shown in FIG. 3 is a pressing state in which the upper roller 132 is pressed toward the lower roller 131 in a direction perpendicular to the axis. In the pressure contact state, the upper roller 132 is driven to rotate as the lower roller 131 is driven to rotate. The belt front roller pair 130 conveys the paper P when the lower roller is rotationally driven in a state where the paper P is sandwiched in the nip between the lower roller 131 and the upper roller 132.

  Similarly to the belt front roller pair 130, the belt rear roller pair 140 also transports the paper P by a lower roller 141 that is a driving roller and an upper roller 142 that is pressed against the lower roller 141 and is driven to rotate. However, the belt rear roller pair 140 is provided downstream of the conveyance belt 110 and is used to carry out the paper P on the conveyance belt 110 from the reading conveyance device 100. Further, the upper roller 142 can also move up and down as indicated by arrows in FIG. 3, and can be brought into a pressed state shown in FIG. 3 and a separated state separated from the lower roller 141.

  In FIG. 3, the distance from the belt front roller pair 130 to the measurement position M is indicated by X, and the distance from the measurement position M to the belt rear roller pair 140 is indicated by Y. Further, the distance from the belt front roller pair 130 to the belt rear roller pair 140 is indicated by Z. That is, the distance Z is the sum of the distance X and the distance Y.

  In addition, the paper P that has been transported to the reading transport device 100 is sent onto the transport belt 110 by the belt front roller pair 130. The paper P on the transport belt 110 passes through the measurement position M where the laser beam L is irradiated by the rotation of the transport belt 110. Therefore, a streak of light by the laser beam L is formed on the paper P at the measurement position M. The imaging unit 70 continuously captures the light streaks on the paper P at the measurement position M, and outputs the captured data to the CPU 92.

  When the paper P is not curled or wavy, the streak of light on the paper P at the measurement position M imaged by the imaging unit 70 is straight. On the other hand, when the paper P is curled or wavy, the light streaks on the paper P at the measurement position M imaged by the imaging unit 70 is distorted depending on the degree of the curl or wavy.

  That is, the CPU 92 can obtain the shape of the paper P at the measurement position M by calculation from the shape of the streak of light imaged by the imaging unit 70. Further, the CPU 92 can obtain the overall shape of the sheet P by calculation from data obtained by the imaging unit 70 continuously imaging a plurality of times from the leading end to the trailing end in the transport direction of the sheet P passing the measurement position M. . Thereby, the shape of the paper P can be measured.

  Here, while the paper P passes through the measurement position M, it is preferable that the paper P is not restrained by being caught in either the belt front roller pair 130 or the belt rear roller pair 140. For example, when the trailing edge of the paper P in the conveyance direction where the curl is generated is sandwiched between the nips of the belt front roller pair 130, the leading edge of the paper P may float from the carrying surface of the conveyance belt 110. is there. This is because the shape on the front end side cannot be accurately measured when the measurement position M is passed with the position on the front end side of the paper P floating.

  The reading and conveying apparatus 100 according to the present embodiment conveys the paper P while switching the belt front roller pair 130 and the belt rear roller pair 140 between a pressure contact state and a separated state. Thus, when at least a part of the paper P passes through the measurement position M, the belt front roller pair 130 and the belt rear roller pair 140 do not sandwich the paper P.

  FIG. 4 is a diagram for explaining the switching timing between the pressure contact state and the separation state in the belt front roller pair 130 and the belt rear roller pair 140. The length PL1 shown in FIG. 4 is the maximum length of the sheet P having the longest length in the transport direction among the sheets supported by the image forming apparatus 1.

  In this embodiment, the distance Z from the belt front roller pair 130 to the belt rear roller pair 140 is set to be slightly longer than the maximum length PL1 of the paper P. Further, the measurement position M is set at an intermediate position between the belt front roller pair 130 and the belt rear roller pair 140. That is, the distance X from the belt front roller pair 130 to the measurement position M and the distance Y from the measurement position M to the belt rear roller pair 140 are the same distance.

  First, as shown in FIG. 4A, when the paper P is conveyed to the reading and conveying apparatus 100, the belt front roller pair 130 is in a pressure contact state. Accordingly, the paper P that has been transported to the reading transport device 100 is transported to the transport belt 110 by the belt front roller pair 130.

  Next, as shown in FIG. 4B, before the paper P is transported on the transport belt 110 and the leading end of the paper P in the transport direction reaches the measurement position M, the belt front roller pair 130 is brought into a separated state. Specifically, the upper roller 132 of the belt front roller pair 130 is moved upward. For this reason, in the state shown in FIG. 4B, the paper P is in an unconstrained state in which it is not restrained by any member. Therefore, the leading edge of the paper P reaches the measurement position M in an unconstrained state, and the paper P passes through the measurement position M.

  Further, the leading edge of the paper P transported on the transport belt 110 reaches the belt rear roller pair 140. Then, as shown in FIG. 4c, before the leading edge of the paper P conveyed on the conveyance belt 110 reaches the belt rear roller pair 140, the belt rear roller pair 140 is brought into a separated state. Specifically, the upper roller 142 of the belt rear roller pair 140 is moved upward.

  Further, since the distance Z is slightly longer than the maximum length PL1 of the paper P, as shown in FIG. 4C, the rear end of the paper P in the transport direction of the paper P passes through the front belt roller pair 130 as shown in FIG. After that, the upper roller 132 is moved downward to return to the pressure contact state. The belt front roller pair 130 does not need to return to the press-contact state immediately after the rear end of the paper P in the transport direction passes, but returns to the press-contact state until the front end in the transport direction of the next paper P arrives. It only has to be done.

  Subsequently, as shown in FIG. 4d, the belt rear roller pair 140 moves upward when the paper P is transported on the transport belt 110 after the rear end in the transport direction of the paper P passes the measurement position M. The roller 142 is moved downward to return to the pressure contact state. As a result, the paper P is sandwiched between the belt rear roller pair 140. Therefore, thereafter, the paper P is carried out from the reading and conveying apparatus 100 by the belt rear roller pair 140.

  As described with reference to FIG. 4, the reading and conveying apparatus 100 puts the paper P in an unconstrained state before the leading edge reaches the measurement position M. Further, the sheet P is left in an unconstrained state until the trailing edge passes the measurement position M. For this reason, the reading / conveying device 100 does not move the paper P while the paper P passes through the measurement position M, that is, while at least a part of the paper P passes through the measurement position M. It can be transported in a restrained state. Therefore, the image pickup unit 70 can pick up an image of the paper P that has not been deformed due to being in an unconstrained state. That is, the actual shape of the paper P that is not deformed can be accurately measured.

  Here, a case will be described in which the front-belt roller pair 130 and the rear-belt roller pair 140 are not separated from each other, and the shape measurement of the unrestrained paper P is always performed in the pressure contact state. In this case, the rear end of the paper P must pass through the belt front roller pair 130 before the front end of the paper P reaches the measurement position M. That is, the distance X from the belt front roller pair 130 to the measurement position M must be longer than the maximum length PL1 of the paper P.

  In addition, the rear end of the paper P must pass through the measurement position M before the front end of the paper P reaches the belt rear roller pair 140. That is, the distance Y from the measurement position M to the belt rear roller pair 140 must be longer than the maximum length PL1 of the paper P. That is, the distance Z from the belt front roller pair 130 to the belt rear roller pair 140 must be at least twice as long as the maximum length PL1 of the paper P.

  On the other hand, as described above, the distance Z is set to, for example, the maximum length of the sheet P by transporting the sheet P while switching the belt front roller pair 130 and the belt rear roller pair 140 between the pressure contact state and the separated state. It can be done only slightly longer than PL1. Therefore, it can be seen that the reading and conveying apparatus 100 can be downsized. Further, the image forming apparatus 1 including such a reading and conveying apparatus 100 can be reduced in size because the reading and conveying apparatus 100 is small. In this embodiment, the distance Z only needs to be at least shorter than the maximum length PL1 of the paper P. Among the papers supported by the image forming apparatus 1, the distance Z is shorter than the minimum length of the paper P having the shortest length in the transport direction. It is even better if it is too short.

  Even when the shape measurement of the paper P is performed in the non-restrained state while the front belt pair 130 and the rear belt roller pair 140 are both pressed, the distance Z is set to the maximum length PL1 by stopping the conveyance of the paper P. It is possible to do a little longer than. The paper P having the maximum length PL1 is stopped between the belt front roller pair 130 and the belt rear roller pair 140, and the measurement position M by the imaging unit 70 and the irradiation unit 71 is stopped from the front end of the paper P to the rear end during the stop. This is because it is only necessary to move up to. However, stopping the conveyance of the paper P significantly reduces the productivity of image formation. On the other hand, in the present embodiment, the shape of the sheet P can be measured while being conveyed by the reading and conveying apparatus 100, so that the productivity of image formation is not reduced.

  Further, the CPU 92 determines the amount of curl correction and the direction of correction in the decurling device 80 based on the measured degree of curling of the paper P before the paper P reaches the decurling device 80 after passing through the measurement position M. Adjust. Specifically, the pressure contact force at the correction nip N3 of each decal roller 81 is adjusted. Therefore, the paper P passes through the decurling device 80 in which the correction amount and the correction direction of the curl and the like are adjusted. After the curl and the like are corrected, the paper P is discharged to the paper discharge tray 55 by the paper discharge roller 54.

  Any of the sheets P discharged in this way has no trouble in stacking on the sheet discharge tray 55. This is because the correction amount and the correction direction of the paper P in the decurling device 80 are determined based on the actual shape of the measured paper P. That is, curling and undulation are appropriately removed by the decurling device 80. Thus, even when a plurality of discharged sheets P are bound and bound, the bookbinding quality is high.

  Alternatively, the temperature of the heater 62 in the fixing processing unit 3 can be fed back based on the measured shape of the paper P. Thereby, the degree of curl or the like in the next paper P can be reduced. This is because the feedback to the temperature of the heater 62 can be performed based on the actual shape of the paper P imaged by the imaging unit 70.

  As described above in detail, the image forming apparatus 1 according to the present embodiment includes the reading and conveying apparatus 100 in the correction unit 4. The reading and conveying apparatus 100 includes a conveying belt 110 that carries the paper P and passes it to the measurement position M. A belt front roller pair 130 is disposed upstream of the conveyance belt 110, and a belt rear roller pair 140 is disposed downstream. Both the belt front roller pair 130 and the belt rear roller pair 140 can be in a pressure contact state and a separated state. Further, at the measurement position M, the shape of the paper P is measured by the imaging unit 70. When the paper P, at least a part of which passes through the measurement position M, is on the belt front roller pair 130 and the belt rear roller pair 140, each roller pair takes a separated state so as not to sandwich the paper P. . Therefore, the accurate shape of the paper P can be measured by the imaging unit 70 without reducing the productivity of image formation. Further, the overall length of the reading / conveying apparatus 100 can be shortened, and the entire apparatus can be miniaturized.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the decurling device 80 is not limited to the one that corrects the curl or the like of the paper P by adjusting the pressure contact force in the correction nip N3. For example, the decurling device 80 has a function of removing the curl or the like by supplying moisture to the paper P. It may be. Further, for example, in the above embodiment, the belt rear roller pair 140 is separated before the leading edge of the paper P arrives after the paper P is conveyed to the reading and conveying apparatus 100 (FIG. 4). May be already separated when being conveyed to the reading and conveying apparatus 100. Further, for example, the belt front roller pair 130 and the belt rear roller pair 140 may each switch the pressure contact state and the separated state by moving the lower roller. Alternatively, the upper and lower rollers may be moved to switch between the pressed state and the separated state.

  Further, for example, the distance X from the belt front roller pair 130 to the measurement position M and the distance Y from the measurement position M to the belt rear roller pair 140 may be different distances. For example, the distance Z from the belt front roller pair 130 to the belt rear roller pair 140 may be shorter than the maximum length of the paper P.

  Further, for example, in the above embodiment, the shape of the entire surface from the front end to the rear end of the paper P is measured by the light cutting method, but this is not a limitation. That is, only the shape of a part of the measurement target area of the paper P set in the conveyance direction of the paper P may be measured. This is because the overall shape of the paper P can be calculated by estimation from the shape of the measurement target region. In this case, it is only necessary to place the paper P in an unconstrained state while the measurement target area of the paper P passes through the measurement position M.

  For example, when the measurement target region is from the leading edge of the paper P to the center in the conveyance direction of the paper P, the belt front roller pair 130 is moved before the leading edge of the paper P, that is, the leading edge of the measurement target region reaches the measurement position M. What is necessary is just to set it as a separation state. The belt front roller pair 130 in the separated state may be returned to the pressure contact state after the center in the transport direction of the paper P, that is, the rear end of the measurement target region has passed the measurement position M. Further, the belt rear roller pair 140 may be brought into a pressure contact state after the rear end of the measurement target region passes the measurement position M.

[Second form]
The second embodiment will be described. The image forming apparatus according to this embodiment is different from the first embodiment in the configuration of the reading and conveying apparatus. Specifically, the reading and conveying apparatus of the present embodiment has a configuration for restraining the sheet at a position on the conveying belt.

  FIG. 5 shows a schematic diagram of a reading and conveying apparatus 200 according to the second embodiment. FIG. 6 is a plan view of the conveyance belt 210 of the reading conveyance device 200. The configuration of the image forming apparatus 1 other than the reading and conveying apparatus 200 is the same as that of the first embodiment (FIGS. 1 and 2).

  As shown in FIG. 5, the reading and conveying apparatus 200 includes a conveying belt 210, a belt front roller pair 130, and a belt rear roller pair 140 as a configuration for conveying the paper P. For the belt front roller pair 130 and the belt rear roller pair 140, the upper rollers 132 and 142 can be brought into a pressure contact state and a separated state with respect to the lower rollers 131 and 141, respectively, as in the first embodiment.

  The reading and conveying apparatus 200 has ducts 220 and 230 inside the conveying belt 210. The duct 220 is disposed upstream of the measurement position M on the inner side of the conveyor belt 210. The duct 230 is disposed downstream of the measurement position M inside the conveyor belt 210.

  The duct 220 has a space 221 inside. An opening 222 is formed on the upper side. For this reason, the space 221 communicates with the outside of the duct 220 through the opening 222. The duct 220 has an opening 222 close to the upper lower surface of the transport belt 210.

  The duct 230 is the same as the duct 220. That is, an opening 232 having a space 231 and communicating the space 231 with the outside is formed on the upper side of the duct 230. The duct 230 is provided with an opening 232 in the vicinity of the upper lower surface of the conveyor belt 210.

  Further, as shown in FIG. 6, fans 223 and 233 are connected to the ducts 220 and 230, respectively. The fan 223 discharges the air in the space 221 inside the duct 220 to the outside of the duct 220. Therefore, when the fan 223 is driven, the duct 220 can suck air outside the duct 220 from the opening 222. Similarly, the fan 233 discharges the air in the space 231 inside the duct 230 to the outside of the duct 230. Therefore, when the fan 233 is driven, air outside the duct 230 is sucked from the opening 232. As shown in FIG. 6, the openings 222 and 232 of the ducts 220 and 230 are both shorter in the width direction than the transport belt 210.

  A plurality of through holes that penetrate the belt in the thickness direction are formed in the transport belt 210 of this embodiment. For this reason, when the fan 223 is driven, the duct 220 sucks air on the carrying surface of the paper P of the transport belt 210. The area of the carrying surface where the suction by the duct 220 is performed is indicated by A in FIG. The area A is upstream of the measurement position M in the transport direction of the paper P. When the fan 233 is driven, the duct 230 sucks air on the carrying surface of the transport belt 210 in the region indicated by B in FIG. The area B is downstream of the measurement position M in the transport direction of the paper P.

  The ducts 220 and 230 can hold the paper P in the areas A and B on the transport belt 210 by suction. That is, the ducts 220 and 230 can restrain the paper P in the areas A and B on the transport belt 210 by suction. The paper P held by the ducts 220 and 230 on the upper surface of the transport belt 210 can move in the transport direction together with the upper surface of the transport belt 210 because the transport belt 210 is rotated.

  Next, the relationship between the timing of suction by the ducts 220 and 230 and the switching timing of the pressure contact state and the separation state in the belt front roller pair 130 and the belt rear roller pair 140 will be described with reference to FIG. The switching timing between the pressure contact state and the separation state of the belt front roller pair 130 and the belt rear roller pair 140 is basically the same as the timing described in FIG. In FIG. 7, the areas A and B where the suction is performed by the ducts 220 and 230 are indicated by “ON”, and the areas A and B where the suction is not performed are indicated by “OFF”.

  First, as shown in FIG. 7a, when the paper P is transported to the reading transport device 200 and passes through the pair of pre-belt rollers 130 in a pressure contact state, suction in the region A is turned on. Therefore, the leading end side of the paper P that has passed through the belt front roller pair 130 is held in the region A on the upper surface of the transport belt 210. At this time, suction in the region B is OFF.

  Next, as shown in FIG. 7b, the sheet P is conveyed while being held on the conveying belt 210 while being sandwiched between the pair of front belt rollers 130, and before the leading edge of the sheet P reaches the measurement position M, first, , The belt front roller pair 130 is set in a separated state. Subsequently, as shown in FIG. 7c, after the belt front roller pair 130 is separated, the suction in the region A is turned off before the leading edge of the paper P reaches the measurement position M. For this reason, in the state shown in FIG. 7c, the paper P is in an unconstrained state in which it is not restrained by any member. Therefore, the leading edge of the paper P reaches the measurement position M in an unconstrained state and passes through the measurement position M.

  Then, as shown in FIG. 7d, when the leading edge of the sheet P conveyed on the conveying belt 210 in an unconstrained state passes the position of the belt rear roller pair 140, and the trailing edge of the sheet P passes the measurement position M. First, the suction in the area B that has been turned OFF is turned ON. As a result, the rear end side of the sheet P whose rear end has passed the measurement position M is held in the region B on the transport belt 210. As shown in FIG. 7d, the belt front roller pair 130 is returned to the pressure contact state after the rear end in the transport direction of the paper P passes through the belt front roller pair 130.

  After the suction in the region B is turned ON (FIG. 7d), the belt rear roller pair 140 that has been separated before the leading edge of the paper P arrives is returned to the pressure contact state as shown in FIG. 7e. As a result, the paper P sandwiched between the belt rear roller pair 140 is carried out of the reading and conveying apparatus 100 by the belt rear roller pair 140. The suction in the area B may be turned off before the leading edge of the next sheet P reaches the area B after the belt rear roller pair 140 is returned to the pressure contact state.

  As described with reference to FIG. 7, in the reading and conveying apparatus 200, when the sheet P is conveyed from the pair of front belt rollers 130 onto the conveying belt 210, suction is performed by the duct 220 while the sheet P is being conveyed. The roller pair 130 is set to a separated state. In addition, after the belt front roller pair 130 is separated, the suction by the duct 220 is stopped before the leading edge of the paper P reaches the measurement position M. Therefore, before the leading edge of the paper P reaches the measurement position M, it can be brought into an unconstrained state.

  Here, when the belt front roller pair 130 is moved away from the pressure contact state, an impact accompanying the operation of the upper roller 132 is generated. Further, the paper P passing through the belt front roller pair 130 at the time of separation may be affected by the airflow generated by the upper roller 132 moving upward, and may stick to the upper roller 132 and be pulled upward, for example. . Further, the paper P may stick to the upper roller 132 due to static electricity and be pulled upward. However, as described above, when the front roller side 130 of the belt P is separated while the leading end side of the paper P is held on the transport belt 210 by suction with the duct 220, the paper P is subjected to an impact or the like at the time of separation. Will not be affected. Therefore, it is possible to reliably transfer the paper P from the belt front roller pair 130 to the upper surface of the transport belt 210.

  Further, in the reading and conveying apparatus 200, after the trailing edge of the paper P has passed the measurement position M, suction is performed by the duct 230. When the paper P is conveyed from above the conveying belt 210 to the belt rear roller pair 140, the separated belt rear roller pair 140 is brought into a pressure contact state while the suction is performed by the duct 230. . That is, since the rear end of the paper P passes through the measurement position M, the paper P is brought into a restrained state, so that the paper P can pass through the measurement position M in an unrestrained state. Further, as described above, the rear belt roller 140 is brought into a pressure contact state while the rear end side of the paper P is held on the transport belt 210 by suction by the duct 230, so that the paper P is subjected to an impact during the pressure contact. It is not affected by. Therefore, it is possible to reliably transfer the paper P from the upper surface of the conveyance belt 210 to the belt rear roller pair 140.

  Therefore, even with the reading / conveying device 200, the image pickup unit 70 can pick up an image of the paper P that has not been deformed due to being in an unconstrained state. That is, the actual shape of the paper P that is not deformed can be accurately measured. The paper P is properly corrected by the decurling device 80 in which the correction amount and the correction direction of the curl and the like are adjusted based on the shape accurately measured at the measurement position M. As a result, the paper is discharged to the paper discharge tray 55. For this reason, there is no hindrance in the accumulation of each paper P in the paper discharge tray 55, and the bookbinding quality using the discharged paper P is high. Alternatively, feedback to the temperature of the heater 62 in the fixing processing unit 3 can be appropriately performed based on the measured accurate shape of the paper P, and the degree of curling on the next paper P can be reduced.

  Furthermore, since both the front belt roller pair 130 and the rear belt roller pair 140 can be transported while switching between the pressure contact state and the separation state as described above, the reading transport device is the same as in the first embodiment. 200 can be miniaturized. Further, the image forming apparatus 1 including such a reading / conveying device 200 can be reduced in size because the reading / conveying device 200 is small. In addition, also in the present embodiment, the shape of the paper P can be measured while being conveyed by the reading and conveying apparatus 200, so that the productivity of image formation is not reduced.

  As described in detail above, the reading and conveying apparatus 200 of this embodiment has the ducts 220 and 230 inside the conveying belt 210 in which a plurality of through holes are formed. The ducts 220 and 230 can hold the paper P by suction in the areas A and B on the transport belt 210, respectively. Accordingly, it is possible to suppress the influence on the paper P due to an impact or the like generated when the front belt pair 130 and the rear belt pair 140 are switched between the pressed state and the separated state, and the paper P can be reliably conveyed.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. That is, the shape of only a part of the measurement target area of the paper P set in the conveyance direction of the paper P may be measured. In this case, it is only necessary to place the paper P in an unconstrained state while the measurement target area of the paper P passes through the measurement position M.

  For example, when the measurement target region is from the leading edge of the paper P to the center in the conveyance direction of the paper P, the belt front roller pair 130 is moved before the leading edge of the paper P, that is, the leading edge of the measurement target region reaches the measurement position M. What is necessary is just to make it a separation state and to further stop the suction of the duct 220. The belt front roller pair 130 in the separated state may be returned to the pressure contact state after the center in the transport direction of the paper P, that is, the rear end of the measurement target region has passed the measurement position M. Further, after the rear end of the measurement target region has passed the measurement position M, suction of the duct 230 is started, and the separated belt rear roller pair 140 may be brought into a pressure contact state.

[Third embodiment]
A third embodiment will be described. The image forming apparatus according to this embodiment is different from the above embodiment in the configuration of the reading and conveying apparatus. The reading and conveying apparatus of this embodiment is the same as that of the second embodiment in that it has a configuration for restraining the sheet at a position on the conveying belt. In this embodiment, the suction area of the paper on the transport belt provided upstream and downstream of the measurement position M is different from the second embodiment in the suction state for each small area divided in the paper transport direction. Can be switched between enabled and disabled.

  FIG. 8 shows a schematic diagram of a reading and conveying apparatus 300 according to the third embodiment. The configuration of the image forming apparatus 1 other than the reading and conveying apparatus 300 is the same as that of the first embodiment (FIGS. 1 and 2).

  As shown in FIG. 8, the reading and conveying apparatus 300 includes a conveying belt 210, a belt front roller pair 130, and a belt rear roller pair 140 as a configuration for conveying the paper P. For the belt front roller pair 130 and the belt rear roller pair 140, the upper rollers 132 and 142 can be brought into a pressure contact state and a separated state with respect to the lower rollers 131 and 141, respectively, as in the first embodiment. Further, a plurality of through holes are formed in the transport belt 210 as in the second embodiment.

  The reading and conveying apparatus 300 includes ducts 320 and 330 inside the conveying belt 210. The duct 320 is disposed upstream of the measurement position M on the inner side of the conveyor belt 210. The duct 330 is disposed downstream of the measurement position M inside the conveyor belt 210.

  The duct 320 has a space 321, and an opening 322 that allows the space 321 to communicate with the outside is formed above the duct 320. The duct 330 also has a space 331 and an opening 332 that allows the space 331 to communicate with the outside is formed on the upper side of the duct 330. The ducts 320 and 330 have openings 322 and 332 adjacent to the upper lower surface of the conveyor belt 210, respectively. Furthermore, the ducts 320 and 330 are connected to fans for discharging the air in the internal spaces 321 and 331 to the outside, as in the second embodiment.

  The duct 320 of this embodiment has shutters 323 and 324 that open and close the opening 322. The shutter 323 can open or close the upstream side of the opening 322 in the transport direction of the paper P. The shutter 324 can open or close the downstream side of the opening 322 in the transport direction of the paper P.

  That is, when the shutter 323 is in the open state, the duct 320 can effectively perform suction in the area A1 on the upstream side in the transport direction of the paper P in the area A shown in FIG. On the other hand, by closing the shutter 323, the suction of the duct in the region A1 can be invalidated. Further, when the shutter 324 is in the open state, the duct 320 can effectively perform suction in the area A2 on the downstream side in the transport direction of the paper P in the area A shown in FIG. On the other hand, by closing the shutter 324, the suction of the duct in the area A2 can be invalidated. In addition, when both the shutters 323 and 324 are in the open state, suction is effectively performed in the entire area A.

  In addition, the duct 330 of this embodiment has shutters 333 and 334 that open and close the opening 332. The shutter 333 can open or close the upstream side of the opening 332 in the transport direction of the paper P. The shutter 334 can open or close the downstream side of the opening 332 in the transport direction of the paper P.

  That is, when the shutter 333 is in the open state, the duct 330 can effectively perform suction in the region B1 on the upstream side in the transport direction of the paper P in the region B shown in FIG. On the other hand, by closing the shutter 333, the suction of the duct in the region B1 can be invalidated. Further, when the shutter 334 is in the open state, the duct 330 can effectively perform suction in the region B2 on the downstream side in the transport direction of the paper P in the region B shown in FIG. On the other hand, by closing the shutter 334, the suction of the duct in the region B2 can be invalidated. Note that when both the shutters 333 and 334 are in the open state, suction is effectively performed in the entire region B.

  Therefore, the reading and conveying apparatus 300 according to this embodiment can hold the sheet P on the upper surface of the conveying belt 210 by suction for each of the areas A1, A2, B1, and B2 to be in a restrained state.

  Here, in the image forming apparatus 1, paper P having various sizes may be used. Usually, the distance X, the distance Y, the distance Z, and the like are set by the maximum length PL1 of the sheet P having the longest length in the transport direction among the sheets supported by the image forming apparatus 1. The same applies to the lengths of the areas A and B in the transport direction of the paper P.

  However, as shown in FIG. 8, when the length PL2 in the transport direction of the paper P is shorter than the areas A and B, the paper P is held on the transport belt 210 in the suction for each of the areas A and B. May not be performed properly. This is because most of the suction by the ducts 320 and 330 is performed from the through-holes of the conveyance belt 210 where the paper P is not carried. For this reason, there is a possibility that the paper P having a short length in the transport direction cannot be properly transferred from the belt front roller pair 130 to the transport belt 210 or from the transport belt 210 to the belt rear roller pair 140. is there.

  Therefore, the ducts 320 and 330 according to the present embodiment, when holding the paper P having a short length in the transport direction on the transport belt 210 by suction, are provided for each of the regions A1, A2, B1, and B2 having a short length in the transport direction. The suction state is switched between enabled and disabled. As a result, it is possible to prevent suction from a place where the paper P is not carried, and to appropriately hold the paper P on the transport belt.

  The opening / closing timing of the shutters 323, 324, 333, and 334 will be described with reference to FIG. FIG. 9 shows that the area where the suction is effectively performed is “ON” and the area where the suction is invalid is “OFF” due to the suction by the ducts 320 and 330 and the open / closed state of the shutters 323, 324, 333 and 334. ", Respectively. Further, the sheet P shown in FIG. 9 has a shorter length in the transport direction than both the areas A and B, as described in FIG.

  First, as shown in FIG. 9a, when the paper P is transported to the reading transport device 300 and passes through the pair of pre-belt rollers 130 in the pressure contact state, the suction in the region A1 is turned on. For this reason, the leading end side of the paper P that has passed through the belt front roller pair 130 is held in the region A1 on the transport belt 210. At this time, the areas A2, B1, and B2 are OFF.

  Next, as shown in FIG. 9b, when the trailing edge of the paper P passes through the area A1 by the rotation of the conveying belt 210, the suction in the area A1 is turned off. At this time, since the paper P is on the area A2, the suction in the area A2 is ON. Therefore, the paper P is held in the area A2 on the transport belt 210. Note that the sheet P shown in FIG. 9 is shorter in the conveyance direction than the area A. For this reason, the belt front roller pair 130 is not particularly required to be in a separated state. Further, the suction in the area A2 is turned OFF after the state shown in FIG. 9B and before the leading edge of the paper P reaches the measurement position M. The leading edge of the paper P reaches the measurement position M in an unconstrained state, and the paper P passes through the measurement position M.

  Subsequently, as shown in FIG. 9c, when the rear end of the sheet P conveyed in an unconstrained state on the conveying belt 210 passes the measurement position M, the suction in the area B1 that has been turned off is turned ON. As a result, the paper P whose rear end has passed the measurement position M is held in the region B1 on the transport belt 210.

  When the sheet P conveyed on the conveying belt 210 is in the area B2, the suction in the area B2 is turned on. Then, as shown in FIG. 9d, the suction in the region B2 is turned ON, and the leading end of the sheet P is in a pressure contact state with the trailing end side of the sheet P held in the region B2 on the transport belt 210. 140 is passed. When the trailing edge of the sheet P conveyed from the state shown in FIG. 9c passes through the area B1, the suction at B1 is turned off. As a result, the paper P sandwiched between the belt rear roller pair 140 is carried out from the reading and conveying apparatus 300 by the belt rear roller pair 140.

  Therefore, the reading / conveying device 300 enables (ON) or disables (OFF) the suction for each of the areas A1, A2, B1, and B2 by suction using the ducts 320 and 330 and opening and closing of the shutters 323, 324, 333, and 334. can do. Therefore, it can be seen that even if the paper P is short in the transport direction, the transport can be reliably performed. Further, while at least a part of the sheet P passes through the measurement position M, it can be conveyed in an unconstrained state. As a result, the actual shape of the paper P that has not been deformed due to the unconstrained state can be accurately measured.

  Naturally, in the case of the sheet P having a long length in the transport direction, suction can be performed for each of the areas A and B by the ducts 320 and 330 as in the case described in the second embodiment.

  As described above in detail, the reading and conveying apparatus 300 according to the present embodiment can enable (ON) or disable (OFF) suction for each of the areas A1, A2, B1, and B2. Therefore, even the paper P having a short length in the transport direction can be reliably transported.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, more shutters in the opening of the duct may be provided in the paper transport direction.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Image forming part 3 ... Fixing process part 4 ... Correction | amendment part 70 ... Imaging part 71 ... Irradiation part 100 ... Reading conveyance apparatus 110 ... Conveyance belt 130 ... Belt front roller pair 140 ... Belt rear roller pair L ... Laser beam M ... Measurement position P ... Paper

Claims (8)

In the paper shape measuring apparatus for measuring the curved shape of the paper at the measurement position while passing the paper through the measurement position,
A transport unit for guiding the paper to the measurement position by carrying the paper on a carrying surface;
At least one of the upstream and downstream of the measurement position in the transport unit is provided at a distance within the length in the paper transport direction from the measurement position, and the restraint state and restraint state for restraining a part of the paper are released. A constraining member in an unconstrained state;
An imaging unit that images the measurement position when a measurement target region that is at least a part in the paper conveyance direction passes;
An irradiating unit that irradiates light to a partial area in the conveyance direction of the paper at the measurement position;
The restraining member is
When at least a part of the measurement target area of the paper passes through the measurement position, an unconstrained state is taken.
A paper shape measuring apparatus, which is in a constrained state when not in a non-constrained state. In the paper shape measuring device according to claim 1,
The transport unit is
An upper end of the outer peripheral surface of the endless belt member as the carrying surface, and a belt transport unit that rotates the belt member in a direction in which the upper surface moves in the paper transport direction;
As one of the restraining members, it has an upstream conveying roller pair provided upstream of the belt conveying unit and capable of being pressed or separated toward or away from at least one of the belt conveying unit,
The upstream conveying roller pair is:
In the restrained state, it takes a pressure contact state, and in the unrestrained state, it takes a separated state.
About the paper being transported
The leading edge of the paper takes a pressure contact state before reaching the upstream conveying roller pair,
When the leading end of the measurement target area of the paper reaches a separation position provided between the pair of upstream transport rollers and the measurement position, a separation operation is performed for taking a separation state. Paper shape measuring device. In the paper shape measuring apparatus according to claim 2,
The belt member is formed with a plurality of through holes penetrating in the thickness direction,
As another one of the restraining members, the air in the upstream suction region on the upstream side of the measurement position on the support surface of the belt member is provided inside the belt member and through the through hole of the belt member. Has an upstream suction part that can suck,
The upstream suction part is
In the restraint state, it takes a suction state in which suction is performed, and in the non-restraint state, it takes a non-suction state in which suction is not performed.
Take the suction state before the upstream conveying roller pair performs the separating operation,
After the upstream conveying roller pair performs a separation operation, the sheet shape measurement is performed before the leading end of the measurement target area of the conveyed sheet reaches the measurement position. apparatus. In the paper shape measuring apparatus according to claim 3,
The upstream suction part is
In the suction state, for each divided upstream suction area obtained by dividing the upstream suction area into a plurality of paper transport directions, a suction invalid state in which suction is invalid or a suction valid state in which suction is not invalid can be set. And
Among the plurality of divided upstream suction areas,
At least the divided upstream suction area that does not carry the paper is in a suction invalid state,
The paper shape measuring apparatus according to claim 1, wherein the divided upstream suction area that is not in a suction invalid state is in a suction valid state. In the paper shape measuring device according to claim 1,
The transport unit is
An upper end of the outer peripheral surface of the endless belt member as the carrying surface, and a belt transport unit that rotates the belt member in a direction in which the upper surface moves in the paper transport direction;
As one of the restraining members, it has a downstream conveying roller pair that is provided downstream of the belt conveying unit and can be pressed against or separated from at least one of them toward the other,
The downstream conveying roller pair is:
In the restrained state, it takes a pressure contact state, and in the unrestrained state, it takes a separated state.
About the paper being transported
The leading edge of the paper is separated until it reaches the downstream conveying roller pair,
When the rear end of the measurement target area of the paper reaches a pressure contact position provided between the measurement position and the pair of downstream conveyance rollers, a pressure contact operation for taking a pressure contact state is performed. Paper shape measuring device. In the paper shape measuring apparatus according to claim 5,
The belt member is formed with a plurality of through holes penetrating in the thickness direction,
As another one of the restraining members, the air in the downstream suction region is provided on the inner side of the belt member, and is downstream of the measurement position on the support surface of the belt member through the through hole of the belt member. Having a downstream suction section that can suck,
The downstream suction part is
In the restraint state, it takes a suction state in which suction is performed, and in the non-restraint state, it takes a non-suction state in which suction is not performed.
Take the suction state before the downstream conveying roller pair performs the pressure contact operation,
The paper shape measuring apparatus according to claim 1, wherein after the downstream conveying roller pair performs a pressure contact operation, a non-suction state is taken until a leading edge of a next sheet reaches the downstream suction unit. In the paper shape measuring apparatus according to claim 6,
The downstream suction part is
In the suction state, for each divided downstream suction region obtained by dividing the downstream suction region into a plurality of paper transport directions, a suction invalid state in which suction is disabled or a suction valid state in which suction is not disabled can be set. And
Among the plurality of divided downstream suction regions,
At least the divided downstream suction area that does not carry paper is in a suction invalid state,
The paper shape measuring apparatus according to claim 1, wherein the divided downstream suction region that is not in a suction invalid state is in a suction valid state. An image forming unit for transferring a toner image to paper;
In an image forming apparatus having a fixing unit that fixes a transferred toner image onto a sheet,
A paper shape measuring device according to any one of claims 1 to 7,
The image forming apparatus, wherein the sheet shape measuring device is provided downstream of both the image forming unit and the fixing unit in the sheet conveyance direction.

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