JP4913658B2 - Curl measuring device, curl measuring method, and image forming apparatus - Google Patents

Description

  The present invention relates to a curl measurement device, a curl measurement method, and the curl measurement device that detect a curved state of a paper when the paper discharged from an external device is conveyed to a paper post-processing device that performs predetermined post-processing. The present invention relates to an image forming apparatus using.

  When a sheet discharged after image formation is transported to a sheet post-processing apparatus that performs post-processing such as stapling, a conveyance failure such as the leading end of the sheet being bent due to the sheet curving upward or downward occurs. There is a case. For such a conveyance failure, the sheet is smoothly formed regardless of whether the sheet material (paper) that is formed and discharged from the discharge roller pair is upwardly curled (curved) or downwardly curled. A sheet post-processing apparatus that can be delivered is disclosed (for example, see Patent Document 1).

JP-A-6-263305

  However, as in the technique of Patent Document 1, even when an image is formed and discharged and the paper is smoothly delivered and conveyed to the paper post-processing device, the paper is curved in the paper post-processing device. There is. As a result, in the paper post-processing apparatus, post-processing is performed on the curved paper, and accurate post-processing of the paper may not be performed. For example, when post-processing such as stapling is performed by a paper post-processing device, after a plurality of sheets are held in the staple tray, the sheets are aligned, and stapling processing is performed on the aligned sheets. A bundle of sheets is bound. At this time, if the sheets in the sheet post-processing apparatus are in different curved states, the alignment of the sheets is not uniform, and an irregular portion is generated in the stapled sheet bundle, and accurate post-processing is performed. There was a case that could not be done. Accordingly, it is necessary to detect the curved state of each sheet and adjust the alignment of the sheet in the sheet post-processing apparatus based on the detection result. However, since the curved state of each sheet is different, the detected curved state is detected. It was difficult.

  The present invention has been made in view of the above, and can accurately detect the height from the center of the sheet to both ends, and can also detect the sheet in the sheet post-processing apparatus based on the detection result. It is an object of the present invention to provide a curl measuring apparatus, a curl measuring method, and an image forming apparatus capable of performing accurate post-processing by performing the above alignment.

In order to solve the above-described problems and achieve the object, the invention according to claim 1 is a conveyance for conveying a sheet discharged from an external device to a sheet post-processing apparatus that performs predetermined post-processing on the sheet. A first guide section provided as a part of the transport path on the upstream side of the path and guiding a central portion of the discharged paper in a flat state; and a first guide section on the downstream side of the first guide section. A second guide portion that is provided as a portion and guides the entire width of the paper in a flat state; and a central portion of the paper that is guided by the first guide portion and before reaching the second guide portion Detecting means for detecting the height from the first end to the two end portions, and the first guide portion includes two first plate-like members that face each other and form the transport path, and the two first plate-like members. The paper is received at each end of the external device side with respect to the conveyance path. A first receiving port provided at a possible predetermined angle, and the second guide portion includes two second plate members facing each other to form the transport path, and the two second plate members. Are disposed at predetermined distance positions downstream of the first receiving port from the first receiving port in a direction in which the sheet is conveyed, and at a predetermined angle at which the sheet can be received with respect to the conveyance path. a curl measuring device according to claim Rukoto and a second receiving opening provided.

The invention according to claim 2 is the curl measuring apparatus according to claim 1, wherein, at the first receiving port, the two first plate-shaped members are conveyed so that a distance between them increases toward the upstream side. Each of the two second plate-like members is inclined with respect to the conveying direction so that the interval increases toward the upstream side .

According to a third aspect of the present invention, in the curl measuring apparatus according to the first aspect, the detection means are provided at different positions, and a plurality of sensors for detecting both ends of the paper, and the plurality of sensors. characterized in that a control unit for calculating the height of the sheet based on the detection result of the is provided.

According to a fourth aspect of the present invention, in the curl measuring apparatus according to the first aspect, the first guide portion and the second guide portion are integrally formed.

According to a fifth aspect of the present invention, as a part of the transport path, upstream of a transport path for transporting a sheet discharged from an external device to a sheet post-processing apparatus that performs predetermined post-processing on the sheet. A first guiding step for guiding the central portion of the discharged paper to a flat state by the provided first guiding portion; and a portion of the transport path provided downstream from the first guiding portion. A second guiding step for guiding the entire width of the sheet to a flat state by the second guiding unit; and the sheet before reaching the second guiding unit while being guided by the first guiding unit. Detection step of detecting the height from the central part to both ends by a detecting means , wherein the first guide part is opposed to the two first plate-like members that form the transport path, and the 2 The first plate-like member at each end on the external device side A first receiving port provided at a predetermined angle capable of receiving the paper with respect to the feeding path, and the second guide portion includes two second plate-like members that face each other and form the transport path. The two second plate-like members are disposed at respective end portions on the external device side at a predetermined distance downstream from the first receiving port in the sheet conveyance direction, and are arranged with respect to the conveyance path. a curl measuring method comprising Rukoto and a second receiving port provided at an angle that can accept the paper.

The invention according to claim 6 includes, as the external device, an image forming unit that forms an image on the paper, the curl measuring device according to claim 1, and the paper post-processing device. The post-processing apparatus is an image forming apparatus that performs the predetermined post-processing based on the height detected by the curl measuring apparatus.

  According to the present invention, by detecting the paper in a state where the central portion of the paper is guided in a flat state, the height from the central portion of the paper to both ends can be accurately detected, and the By performing the sheet alignment in the sheet post-processing apparatus based on the detection result, there is an effect that accurate post-processing can be performed.

  Exemplary embodiments of a curl measurement device, a curl measurement method, and an image forming apparatus using the curl measurement device will be described below in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a cross-sectional view illustrating a configuration of a curl measuring apparatus and a sheet post-processing apparatus according to the first embodiment. The curl measuring apparatus and the sheet post-processing apparatus of the present embodiment are mounted on the image forming apparatus as a part of the image forming apparatus. The image forming apparatus forms an image on a sheet by an image forming unit (not shown) in the apparatus main body, detects a curved state of the sheet in the curl measuring apparatus, and based on a detection result by the curl measuring apparatus in the sheet post-processing apparatus. The paper is post-processed, and the paper is discharged out of the image forming apparatus.

  First, the curl measuring apparatus 1 will be described. The curl measuring apparatus 1 detects the height (curved state) of a curved portion of a curved sheet. As shown in FIG. 1, the curl measuring apparatus 1 receives the paper discharged from the apparatus main body and conveyed in the direction of the arrow P after the image formation is performed by the image forming apparatus main body by the receiving guide unit 3. The height of the curved portion of the received sheet is measured, and the sheet is conveyed into the sheet post-processing device 4 by the conveying roller.

  The receiving guide unit 3 forms a conveyance path for conveying the sheet in the direction of arrow C by two plate-like members provided facing each other, and is conveyed to the sheet post-processing device 4 through the conveyance path. The sheet is guided (guided) in a flat state. The height of the curved portion of the sheet conveyed on the conveyance path is detected by the sensor 2a provided above the conveyance path and the sensor 2b provided below the conveyance path. A detailed description of the receiving guide part 3 will be described later.

  Next, the paper post-processing device 4 will be described. The sheet post-processing device 4 sorts sheets on which image formation has been performed, stapling processes that align a plurality of sheets and bind a bundle of sheets, punch processes that open holes in the sheets, and straight sheet discharge that discharges sheets as they are It performs post-processing of the paper after image formation such as processing. With respect to the paper post-processing device 4 of the present embodiment, a case where stapling processing is performed on the paper conveyed from the curl measuring device 1 will be described.

  The paper post-processing device 4 transports the paper received from the curl measuring device 1 in the direction of arrow D by the pre-stack unit 5 that is a transport path, and discharges it to the staple tray 6 that holds the paper. Then, the sheet conveyed in the direction of arrow E toward the staple tray 6 comes into contact with a leading end stopper (not shown) that aligns the leading ends of the sheets, and a plurality of sheets are held on the staple tray 6.

  Next, the plurality of sheets held on the staple tray 6 are conveyed in a direction opposite to the direction of arrow E so as to be dropped downward by the tapping roller 8, and the rear end portion of the sheet comes into contact with the reference fence 7 to form the sheet. The rear ends of are aligned. Then, the aligned sheets are pressed by a pressing member that prevents the sheets from bulging. Further, when the sheet is conveyed in the direction opposite to the arrow E direction, both ends in the sheet conveying direction are aligned by the jogger 13 to align the sheet bundle.

  The aligned sheet bundle is bound near the center by the stapler 9, and the bound sheet bundle is lifted upward by the discharge claw 10, passes through the staple tray 6, and is discharged to the discharge tray 11. Is done. In this way, when performing stapling processing by aligning sheets in the sheet post-processing apparatus, when a plurality of sheets each having a different curved state are conveyed, an alignment consisting of the tapping roller 8, the tip stopper, the jogger 13, and the pressing member is performed. Even if the mechanism aligns the sheets with a uniform operation, the sheets cannot be accurately aligned, and accurate stapling (post-processing) cannot be executed. Therefore, in the present embodiment, the sheet post-processing apparatus is configured to adjust the alignment mechanism using the detection result of detecting the curved state of each sheet and perform an aligning operation according to the curved state of each sheet. A plurality of sheets are accurately aligned and accurate post-processing is executed. Hereinafter, detection of the curved state of the sheet by the curl measuring device will be described.

  Below, the detail of the acceptance guide part 3 is demonstrated with reference to figures. FIG. 2 is an explanatory view showing details of the receiving guide section. The receiving guide portion 3 shown in FIG. 2 is a view of the inside of the curl measuring apparatus in FIG. 1 as viewed from above. 3 is a cross-sectional view taken along the line AA in the receiving guide portion shown in FIG. 4 is a cross-sectional view taken along the line BB in the receiving guide portion shown in FIG.

  The receiving guide unit 3 is on the upstream side of the conveyance path for conveying the paper 12 discharged from the image forming apparatus main body to the paper post-processing device 4 and is provided at the end on the image forming apparatus main body side in FIG. A first guide portion α from the inlet 3d to the receiving port 3c, and a second guide portion downstream from the first guide portion α and from the receiving port 3c in FIG. 2 to the end of the sheet post-processing device 4 side and β. That is, the receiving guide unit 3 makes the entire width including not only the vicinity of the central part 12b of the paper 12 but also the both end parts 12a flat so as to guide the vicinity of the central part 12b of the paper 12 in a flat state. And a second guiding portion β for guiding. The first guide portion α and the second guide portion β are integrally formed to constitute the receiving guide portion 3.

  Referring to FIGS. 3 and 4, the receiving guide portion 3 is composed of an upper guide portion 3 a and a lower guide portion 3 b which are plate-like members provided opposite to each other, and the upper guide portion 3 a A conveyance path is formed between the lower guide portion 3b. The receiving guide unit 3 receives the paper 12 discharged from the image forming apparatus main body on the right side in FIG. 2 in the conveyance path, and guides the received paper 12 to a flat state, for example, a horizontal state in the present embodiment. (Guide)

  As shown in FIG. 2, the receiving guide portion 3 is provided with a receiving port 3 c and a receiving port 3 d at each end of the upper guide portion 3 a and the lower guide portion 3 b on the image forming apparatus main body side.

  The receiving port 3c is a right end portion in FIG. 2 of the second guide portion β, and is provided at a position for receiving both end portions 12a of the paper 12 in a direction orthogonal to the transport direction (see FIG. 2). The sheet 12 is provided with a predetermined angle capable of receiving the sheet 12 with respect to the conveyance path formed by the 3a and the lower guide portion 3b. That is, the end of the upper guide portion 3a on the image forming apparatus main body side is formed with a predetermined angle, for example, 45 degrees upward with respect to the transport direction, and the end of the lower guide portion 3b on the image forming apparatus main body side. The receiving portion 3c formed at each end of the upper guide portion 3a and the lower guide portion 3b is provided by forming the portion at a predetermined angle, for example, 45 degrees downward with respect to the transport direction. It has been.

  The receiving port 3d is the right end portion of the first guide portion α in FIG. 2 and is provided at a position for receiving the central portion 12b of the paper 12 in the direction orthogonal to the transport direction (see FIG. 2). Similar to the entrance 3c, the entrance 12c is provided with a predetermined angle capable of receiving the paper 12 with respect to the conveyance path formed by the upper guide portion 3a and the lower guide portion 3b. That is, the end of the upper guide portion 3a on the image forming apparatus main body side is formed with a predetermined angle, for example, 45 degrees upward with respect to the transport direction, and the end of the lower guide portion 3b on the image forming apparatus main body side. The receiving portion 3d formed at each end of the upper guide portion 3a and the lower guide portion 3b is provided by forming the portion at a predetermined angle, for example, 45 degrees downward with respect to the transport direction. It has been.

  As described above, the receiving port 3c and the receiving port 3d are formed with an angle upward and downward in the transport direction, so even if the paper is curved upward, it is curved downward. Even the received paper is configured to be received by the receiving guide unit 3.

  As shown in FIG. 2, the position where the receiving port 3c is provided is separated from the position where the receiving port 3d is provided by a predetermined distance on the downstream side in the conveyance direction of the paper 12, so A certain distance can be secured from the time when the paper 12 discharged from the image forming apparatus main body is received by the receiving port 3d to the time when the paper 12 is received by the receiving port 3c.

  Next, a flow of receiving and transporting the paper 12 discharged from the image forming apparatus main body by the receiving guide unit 3 will be described. First, when the sheet 12 is discharged from the image forming apparatus main body on the right side and conveyed, the receiving guide unit 3 receives the sheet 12 through the receiving port 3d. In this case, as shown in FIG. 2, only the vicinity of the central portion 12b of the paper 12 is received, and only the vicinity of the central portion 12b of the paper 12 is guided in a horizontal state. When the sheet 12 is conveyed in the direction of arrow C, the receiving guide unit 3 receives both end portions 12a of the sheet 12 through the receiving port 3c that is separated from the receiving port 3d by a predetermined distance downstream. In this case, as shown in FIG. 2, both ends 12a are received after receiving the vicinity 12b of the center of the sheet 12, and as a result, the entire width (entire) of the receiving sheet 3c is guided horizontally. become. Then, the sheet 12 is conveyed in the direction of arrow C by the conveying roller and is conveyed to the sheet post-processing device 4. In other words, the receiving guide unit 3 horizontally guides the entire sheet 12 by guiding the vicinity of the central part 12b of the sheet 12 discharged from the image forming apparatus main body to the horizontal state and then guiding both ends 12a to the horizontal state. Guide the state.

  As shown in FIG. 2, in the curl measuring apparatus 1, a sensor 2 a is provided above the receiving side of the receiving guide unit 3, and a sensor 2 b is provided below the receiving side of the receiving guide unit 3. It has been. The sensors 2a and 2b detect the sheet 12 in order to detect the height of the curved portion when the conveyed sheet 12 forms a curve around the curved line 12c away from the conveyance path. For example, a distance sensor. Here, the distance sensor emits laser light or infrared light to the measurement object, and the measurement object from the emission position depends on the time it takes for the emitted laser light or infrared light to be reflected back from the measurement object. It is a sensor that can measure the distance.

  The sensors 2a and 2b are in a state where the vicinity of the central portion 12b of the paper 12 discharged from the image forming apparatus main body is received by the receiving port 3d (see FIG. 4), and the both ends 12a of the paper 12 are received. In a state before reaching the entrance 3c (see FIG. 3), both end portions 12a of the paper 12 are detected. That is, when the curved sheet 12 is discharged, if the receiving guide part 3 guides only the vicinity of the central part 12b of the sheet 12 to the horizontal state, the curved both ends 12a are not set to the horizontal state, and the sheet 12 Since the vicinity of the central portion 12b is pressed, an accurate curved portion is formed. In such a state, the sensors 2a and 2b detect both ends 12a of the sheet 12, and both ends 12a of the sheet 12 from the center of the sheet 12 received in the transport path by a control unit (not shown) or the like. Distance, that is, the height h of the curved portion of the paper 12 (see FIG. 3) is calculated.

  As a method for calculating the height of the curved portion, for example, from the sensors 2a and 2b to a position where the curved portion of the paper 12 in the conveyance path is detected in advance, that is, a position before the paper 12 is received by the receiving port 3c in the conveyance path. Is stored in a storage means or the like, and the difference between the detected distance to both ends 12a of the paper 12 and the distance to the stored conveyance path described above and the emission angle of the laser beam or infrared ray by the sensors 2a and 2b are stored. Thus, the height of the bending portion is calculated. In the present embodiment, the height of the curved portion of the paper is detected using distance sensors as the sensors 2a and 2b. However, the present invention is not limited to this, and the height of the curved portion of the paper can be detected. Any sensor may be used.

  The sheet 12 for which the height of the curved portion is calculated as described above is conveyed to the sheet post-processing device 4 and subjected to stapling (post-processing). Then, when the stapling process is performed in the sheet post-processing device 4, the alignment mechanism (the takikoro 8, the tip stopper, the jogger 13, and the pressing member is determined based on the numerical value of the height of the curved portion of the sheet detected by the curl measuring device 1. ) Operation. For example, when the height of the curved portion is high, by adjusting the movement distance of the jogger 13 that aligns both sides of the paper 12, the paper 12 can be accurately aligned without being tilted, and the rear end of the paper 12 The part is brought into contact with a predetermined position of the reference fence 7. Further, when the height of the curved portion is low, adjustment is performed to reduce the moving distance of the jogger 13 that aligns both sides of the paper 12, and similarly, the paper 12 is accurately aligned and placed at a predetermined position of the reference fence 7. Make contact. Thus, when stapling is performed on a correctly aligned bundle of sheets 12 by reducing misalignment that occurs when aligning the bundle of sheets 12, it is possible to perform accurate stapling, that is, post-processing. Become.

  As described above, the curl measuring apparatus 1 according to the present embodiment detects the height of the curved portion of the sheet 12 when only the vicinity of the central portion 12b of the sheet 12 is guided in a horizontal state. It is possible to accurately detect the height from the conveyance path receiving the central portion 12b to the both end portions 12a. Further, the sheet post-processing device 4 of the present embodiment performs alignment of the sheet 12 in the sheet post-processing device 4 based on the detection result of the height of the curved portion of the sheet 12 by the curl measuring device 1. Post-processing such as stapling of the paper 12 can be performed accurately.

(Second Embodiment)
In the first embodiment, the height of the curved portion of the sheet is detected by the two sensors provided above and below the conveyance path. However, in the present embodiment, the height is provided above and below the conveyance path. In addition to the two sensors, the height of the curved portion of the sheet is measured by sensors provided at different positions.

  FIG. 5 is a cross-sectional view illustrating a configuration of a curl measuring apparatus and a sheet post-processing apparatus according to the second embodiment. As in the first embodiment, the curl measuring apparatus and the sheet post-processing apparatus according to the present embodiment are mounted on the image forming apparatus as part of the image forming apparatus. The image forming apparatus forms an image on a sheet by an image forming unit (not shown) in the apparatus main body, detects a curved state of the sheet in the curl measuring apparatus, and based on a detection result by the curl measuring apparatus in the sheet post-processing apparatus. The paper is post-processed, and the paper is discharged out of the image forming apparatus.

  First, the curl measuring apparatus 1 will be described. The curl measuring apparatus 1 detects the height (curved state) of a curved portion of a curved sheet. As shown in FIG. 5, the curl measuring apparatus 1 receives the sheet discharged from the apparatus main body and conveyed in the direction of arrow P after the image formation is performed by the image forming apparatus main body by the receiving guide unit 3. The height of the curved portion of the received sheet is detected, and the sheet is conveyed into the sheet post-processing device 4 by the conveying roller.

  The receiving guide unit 3 forms a conveyance path for conveying the sheet in the direction of arrow C by two plate-like members provided facing each other, and is conveyed to the sheet post-processing device 4 through the conveyance path. The paper is guided to a flat state. The heights of the curved portions of the paper conveyed on the conveyance path are detected by the sensors 2a and 2c provided above the conveyance path and the sensors 2b and 2d provided below the conveyance path. .

  Here, the details of the sheet post-processing device 4 and the receiving guide unit 3 are the same as those in the first embodiment, and thus the description thereof is omitted. The following description will be given with reference to FIG. 5 and FIGS. 2, 3, and 4 in the first embodiment.

  Next, a flow of receiving and transporting the paper 12 discharged from the image forming apparatus main body by the receiving guide unit 3 will be described. In the same manner as the receiving guide portion 3 in the first embodiment, the receiving guide portion 3 of the present embodiment guides the vicinity of the central portion 12b of the paper 12 discharged from the image forming apparatus main body in a horizontal state, and then both ends. The entire sheet 12 is guided to the horizontal state by adding the portion 12a and guiding it to the horizontal state.

  As shown in FIG. 2, in the curl measuring apparatus 1, a sensor 2 a is provided above the receiving side of the receiving guide unit 3, and a sensor 2 b is provided below the receiving side of the receiving guide unit 3. It has been. A sensor 2c is provided above the receiving guide unit 3 on the sheet post-processing device side, and a sensor 2d is provided below the receiving guide unit 3 on the sheet post-processing device side. The sensors 2a, 2b, 2c, and 2d detect the paper 12 in order to detect the height of the curved portion of the paper 12 that has been conveyed, as in the first embodiment. Such as a sensor.

  The sensors 2a, 2b, 2c, and 2d are in a state where the vicinity of the central portion 12b of the paper 12 discharged from the image forming apparatus main body is received by the receiving port 3d (see FIG. 4), and both ends of the paper 12 In a state before the portion 12a reaches the receiving port 3c (see FIG. 3), both end portions 12a of the paper 12 are detected. The sensors 2a, 2b, 2c, and 2d detect both end portions 12a of the paper 12, and from the center portion of the paper 12 that is received in the transport path by a control unit (not shown) to the both end portions 12a of the paper 12. The distance, that is, the height h of the curved portion of the paper 12 (see FIG. 3) is calculated.

  As a method for calculating the height of the curved portion, for example, a position where the curved portion of the paper 12 is detected in the conveyance path from the sensors 2a, 2b, 2c, and 2d in advance, that is, the paper 12 enters the receiving port 3c in the conveyance path. The distance to the front position to be accepted is stored in the storage means, and the difference between the distance to the both ends 12a of the paper 12 detected by each sensor and the distance to the stored conveyance path described above is obtained. Further, as in the first embodiment, the height of the curved portion of the sheet 12 is calculated for each sensor from the difference and the emission angle. Then, by calculating an average value of the heights of the curved portions of the paper 12 obtained by the sensors 2a, 2b, 2c, and 2d, a more accurate height of the curved portions is calculated. In the present embodiment, the height of the curved portion of the paper is detected using a distance sensor as the sensors 2a, 2b, 2c, and 2d, but the height of the curved portion of the paper is not limited to this. Any sensor may be used as long as it can be detected.

  As described above, the sheet 12 with the calculated height of the curved portion is stapled by adjusting the operation of the alignment mechanism based on the calculated numerical value of the height of the curved portion, as in the first embodiment. Processing (post-processing) is performed. In this way, when stapling is performed on a bundle of sheets 12 that are accurately aligned, it is possible to perform accurate stapling.

  As described above, the curl measuring apparatus 1 according to the present embodiment has a sensor 2a, 2b, 2c, and 2d that is high in the curved portion of the paper 12 when only the central portion 12b of the paper 12 is guided horizontally. By detecting the height, the height from the conveyance path receiving the central portion 12b of the paper 12 to both end portions 12a can be detected more accurately. Further, the sheet post-processing device 4 of the present embodiment performs alignment of the sheet 12 in the sheet post-processing device 4 based on the detection result of the height of the curved portion of the sheet 12 by the curl measuring device 1. Post-processing such as stapling of the paper 12 can be performed accurately.

It is sectional drawing which shows the structure of the curl measuring apparatus and paper post-processing apparatus concerning 1st Embodiment. It is explanatory drawing which shows the detail of an acceptance guide part. It is AA sectional drawing in the acceptance guide part shown in FIG. It is BB sectional drawing in the acceptance guide part shown in FIG. It is sectional drawing which shows the structure of the curl measuring apparatus and paper post-processing apparatus concerning 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Curl measuring device 2a, 2b, 2c, 2d Sensor 3 Receipt guide part 3a Upper guide part 3b Lower guide part 3c, 3d Receptacle 4 Paper post-processing apparatus 5 Prestack part 6 Staple tray 7 Reference fence 8 Tachikikoro 9 Stapler 10 Release Claw 11 Paper discharge tray 12 Paper 12a Both ends 12b Center 12c Curved line 13 Jogger

Claims (6)

Provided as a part of the transport path upstream of the transport path for transporting the paper discharged from the external device to a paper post-processing device that performs predetermined post-processing on the paper. A first guide part for guiding the part to a flat state;
A second guide part provided as a part of the transport path downstream from the first guide part, for guiding the entire width of the paper in a flat state;
Detecting means for detecting the height from the center portion of the sheet to both ends before reaching the second guide portion in a state of being guided by the first guide portion ;
The first guide unit includes two first plate members that face each other to form the transport path, and each end of the two first plate members on the external device side with respect to the transport path. A first receiving port provided at a predetermined angle capable of receiving paper,
The second guide portion is formed of two second plate members that face each other to form the conveyance path, and each end of the two second plate members on the external device side from the first receiving port. It is disposed at a position a predetermined distance on the downstream side in the transport direction of the paper, curling, wherein Rukoto and a second receiving port provided at an angle capable of receiving said sheet against said conveying path measuring device. In the first receiving port, the two first plate-like members are inclined with respect to the transport direction so that the interval is widened toward the upstream side,
2. The curl measuring apparatus according to claim 1, wherein at the second receiving port, the two second plate-shaped members are inclined with respect to the transport direction so that a distance between the second plate-shaped members increases toward the upstream side. . The detection means are provided at different positions, respectively.
According to claim 1, a plurality of sensors for detecting the opposite ends of the front Symbol sheet, characterized in that a control unit for calculating the height of the sheet based on the detection result by the plurality of sensors are provided Curl measuring device.   The curl measuring apparatus according to claim 1, wherein the first guide part and the second guide part are integrally formed. The paper discharged from the external device is discharged by a first guide portion provided as a part of the transport path upstream of the transport path for transporting the paper to a paper post-processing device that performs predetermined post-processing on the paper. A first guiding step for guiding the center portion of the paper sheet to a flat state;
A second guiding step of guiding the entire width of the sheet in a flat state by a second guiding portion provided as a part of the transport path downstream from the first guiding portion;
A detection step of detecting the height from the central portion of the sheet to both ends before reaching the second guide portion by a detection means in a state of being guided by the first guide portion ,
The first guide unit includes two first plate members that face each other to form the transport path, and each end of the two first plate members on the external device side with respect to the transport path. A first receiving port provided at a predetermined angle capable of receiving paper,
The second guide portion is formed of two second plate members that face each other to form the conveyance path, and each end of the two second plate members on the external device side from the first receiving port. It is disposed at a position a predetermined distance on the downstream side in the transport direction of the paper, curling, wherein Rukoto and a second receiving port provided at an angle capable of receiving said sheet against said conveying path Measuring method. An image forming unit for forming an image on the paper as the external device;
A curl measuring apparatus according to claim 1;
The paper post-processing device,
The sheet post-processing device performs the predetermined post-processing based on the height detected by the curl measuring device.

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