JP2010269905A - Device for detecting curling of sheet and device for carrying sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for detecting curling of a sheet capable of detecting a curling state accurately regardless of the stiffness or size of the sheet. <P>SOLUTION: The device for detecting the curling includes a distance measuring means for measuring the distance to the paper surface of the sheet, which is arranged opposedly to the paper surface of the sheet carried and passed through a prescribed position, and a curling state determining means for determining the curling state of the sheet from the distance measuring information of the distance measuring means. The distance measuring means measures the distance to the paper surface at least at two places in front and rear of the carrying direction of the sheet passed through the prescribed position, and determines the curling state of the sheet from the distance measuring information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a curl detection device for a sheet mounted on a sheet conveyance device, and the curl detection device is disposed and used in a sheet conveyance device of an image forming apparatus such as a copying machine or a printer.

In general, in an image forming apparatus, sheet curl is extremely important information related to image quality and stackability of discharged sheets, and many sheet curl detection apparatuses that capture information have been proposed.

For example, a curl detection device as disclosed in Patent Document 1 is disclosed. As shown in FIG. 01, the curl detection method is shown by placing a load cell (pressure detection sensor) SE on the sheet conveyance path, and measuring the force pressed by the curled sheet S by the load cell SE. The curl amount is detected by a control device. FIG. 02 shows a case where the curl of the sheet S in the lower curl state is detected. The curl of the sheet S in the upper curl state and the lower curl state can be detected using this one load cell SE, and the curl in the sheet width direction can also be detected from information on the sheet conveyance direction.

Japanese Patent Laid-Open No. 5-221574

However, the above detection method has the following problems.
(1) The measurement value varies depending on the strength of the seat, making it difficult to accurately measure the curl amount.
That is, as shown in FIG. 02, the strength of the waist varies depending on the quality and thickness of the sheet S. Even in the same curled state, in the case of a strong seat (thickness t1), the load cell The pressing force F1 to SE acts greatly, and in the case of a sheet with a low waist (thickness t2: t1> t2), the pushing force F2 (F1> F2) to the load cell SE acts small. As a result, the load cell SE is regarded as a different curl value even if the sheet S is in the same curled state, and accurate measurement cannot be performed.

(2) Depending on the transport path length and the predetermined curl position, accurate measurement is difficult even in the same curl state.
That is, as shown in FIG. 03, the curl amount at the leading end of the sheet S conveyed in the direction of the arrow by the conveying roller pair R reaches C1 when it reaches the P1 position of the conveying distance L1 shown in FIG. C2 value is shown when reaching the P2 position of the transport distance L2 shown in FIG. 2B, and C3 value is shown when reaching the P3 position of the transport distance L3 shown in FIG. In this way, the curl amount C varies depending on the position P where the leading edge of the sheet S is detected. This is because, as shown in FIGS. 04A to 04C, when the curl amount C of the sheet S is not changed by the following factors, the conveyance roller R depends on the position where the sheet S is nipped. It is considered that the leading end position of the sheet S changes.

Further, as shown in FIG. 05, even when the curl amount is detected at the same position for a sheet having the same curl amount, the leading end position of the sheet S may be different. In the state shown in FIG. 5A, the weight of the sheet S on the leading end side is small, and the sheet S has a sufficiently strong lumbar force, and the leading end of the sheet S that protrudes from the conveying roller R bends downward. It is because there is no. In the state shown in FIG. 5B, the weight on the leading end side of the sheet S increases, and the lumbar force of the sheet S does not sufficiently support the weight on the leading end side of the sheet S. The leading end of the sheet S is bent downward. In the state of FIG. 6C, the weight on the leading end side of the sheet S is further increased, and the lumbar force of the sheet S is incapable of supporting the weight on the leading end side of the sheet S. The tip of S is in a state of bending further downward. This factor is considered to be influenced by the lumbar force, gravity, etc. of the sheet S. Even if the curl state of the sheet S is simply captured at a predetermined conveyance position, accurate detection cannot be performed in the state including the above factors, and the result Therefore, there arises a problem that the curl cannot be sufficiently eliminated by the recurling process.

The present invention has been made in view of the above problems, and an object thereof is to provide a curl detection device capable of accurately measuring a curl of a sheet and a sheet conveying device of an image forming apparatus including the curl detection device. .

In order to achieve the above object, a sheet curl detection apparatus according to the present invention is disposed opposite to a sheet surface of a sheet conveyed and passed through a predetermined position, and a distance measuring unit that measures a distance to the sheet surface of the sheet; Curling state determining means for determining the curled state of the sheet from the distance measurement information of the distance measuring means, and the distance measuring means measures at least two positions on the front and back of the sheet passing direction passing through a predetermined position. The curl state determination unit determines the curl state of the sheet by comparing the distance measurement information of the distance measurement unit with the basic information stored in advance.

The distance measuring means measures the distance between three positions, that is, a first sheet surface position of the sheet leading end passing through a predetermined position, a second sheet surface position of the sheet central portion, and a third sheet surface position of the sheet rear end portion. .

Further, by arranging two or more distance measuring means in the sheet width direction, it is possible to simultaneously capture the curl state in the sheet conveyance direction and the width direction.

Actually, the distance measuring means includes three positions, that is, a first paper surface position of the sheet leading edge passing through a predetermined position, a second paper surface position of the sheet central portion, and a third paper surface position of the sheet rear end portion. Captures detection information of at least two points in ranging.

Then, as specific curl characteristic determination, an upper curl or a lower curl is specified by the distance measurement information of the first paper surface position, and the curl undulates vertically by the distance measurement information of the second paper surface position Identify whether
Using the distance measurement information of the third paper surface position, the degree of sheet deflection is specified, and at least two of these pieces of information are combined and compared with basic distance measurement information registered in advance in the storage means, and the closest data is captured. Thus, the curled state of the transport sheet is determined.

In addition, the curl detecting apparatus includes a distance measuring unit that is arranged to face a sheet surface of a sheet that is transported through a predetermined position and measures the distance to the sheet surface of the sheet, and a distance measuring unit that measures the distance. A curl state judging means for judging the curl state of the sheet from distance information, and the distance measuring means measures at least two distances on the front and back of the sheet passing direction passing through a predetermined position. In addition, a sheet having a necessary data value among the data value indicating the curl degree of the upper curl and the lower curl, the data value indicating the degree of waviness, and the data value indicating the degree of sheet deflection is conveyed and passed through a predetermined position. A first step of measuring the distance of at least two of the first, second and third paper surface positions before and after the sheet conveying direction and storing the distance measurement data as basic information; A second step of conveying a sheet for measuring a sheet, passing the predetermined position, and detecting at least two of the first, second, and third paper surface positions of the sheet as distance measurement information; A third step of comparing the basic information stored in step 1 with the distance measurement information of the curl measurement sheet detected in the second step and determining the curl state of the curl measurement sheet. To work.

Further, the curl detection device is mounted on the image forming apparatus and serves as a curl correction unit for correcting the curl of the conveyed sheet based on the curl information of the curl state determination unit of the curl detection device. It is connected to a decal molding apparatus that performs attachment, and is used by being mounted on a sheet conveying apparatus of an image forming apparatus.

According to the present invention, the following effects can be obtained.

1) By detecting the sheet surface at two or more locations and detecting the curl shape from the data at two or more locations, it is possible to determine the curl state in consideration of the sheet waviness and the strength of the seat. Compared with the method of determining the curl shape only at the tip position, it is possible to obtain detection accuracy that is several steps higher.

2) Further, by mounting on an image forming apparatus and connecting to a decal molding apparatus, accurate decurling can be performed.

3) Furthermore, by arranging two or more non-contact sensors of the present application in the sheet width direction, the curl shape in the sheet width direction can be accurately measured with high detection accuracy as well.

4) Furthermore, by using this curl detection device, a sheet whose curl state value has been found can be easily registered in the storage means as basic distance measurement information, and maintenance can be easily performed according to the specifications of the sheet to be handled. .

It is explanatory drawing explaining the conventional curl detection apparatus. It is explanatory drawing explaining the subject by the conventional curl detection method. It is explanatory drawing explaining the subject by the conventional curl detection method. It is explanatory drawing explaining the subject by the conventional curl detection method. It is explanatory drawing explaining the subject by the conventional curl detection method. 1 is an explanatory diagram of an overall configuration of an image forming apparatus equipped with a curl detection device of the present invention. FIG. 7 is an explanatory diagram of a separation state of the post-processing device in FIG. 6. FIG. 7 is a schematic perspective view when a post-processing device is attached to the image forming apparatus in FIG. 6. It is explanatory drawing of the sheet conveying apparatus which has arrange | positioned the curl detection apparatus of this invention. It is a schematic explanatory drawing of the curl detection element used for the curl detection apparatus of this invention. It is a curl detection state explanatory drawing of the curl detection apparatus of this invention. FIG. 11 is an explanatory diagram for explaining a curl detection determination method in FIG. It is explanatory drawing explaining the curl removal method based on the curl ranging data of the curl detection apparatus of this invention.

Embodiments of the present invention will be described below with reference to FIGS.

[Image forming device]
First, an outline of an image forming apparatus provided with a sheet conveying apparatus equipped with a curl detection apparatus of the present invention will be described with reference to FIGS. FIG. 6 is a diagram illustrating the overall configuration of an image forming apparatus equipped with the curl detection device of the present invention, FIG. 7 is a diagram illustrating a separation state of a post-processing device incorporated in the image forming device, and FIG. It is a general | schematic perspective view at the time of attaching an apparatus.

(Overall configuration of image forming apparatus)
As shown in FIG. 6, the image forming apparatus including the sheet conveying device equipped with the curl detecting device of the present invention includes an image forming apparatus main body IMH, an automatic document feeder ADF, a scanner device SCM, and a post-processing device FIN. It consists of.

(About image forming apparatus main body IMH)
The image forming apparatus main body IMH includes a sheet feeding cassette CAS as a sheet supply unit, a manual feed tray HFT in which a sheet can be manually inserted, an image forming unit IFM that forms an image on the fed sheet, and an image formed sheet. The sheet conveying device SHM is provided with a curl detecting means CDM for detecting the curl state.

(About automatic document feeder ADF)
The automatic document feeder ADF stacks a document tray DFT on which a document bundle is set, a sheet conveying unit DFH that separates the document bundle one by one and conveys it to a reading position, and a sheet discharged through the reading position. It includes a paper discharge tray DFT to be accommodated.

(About Scanner SCM)
The scanner device SCM is manually loaded on the platen with a sheet-through reading position for reading a sheet automatically conveyed to a reading position by the automatic document feeder ADF and the automatic document feeder ADF rotated upward. A first carriage SCK1 composed of a light source that selectively moves a flat bed reading position for reading a placed sheet and a reflecting mirror, and a pair of mirrors that move half a distance relative to the amount of movement of the first carriage SCK1 Read by the second carriage SCK2, the lens unit ORU for condensing the image light reflected from the second carriage SCK2, the image reading element CCD disposed at the focal position of the lens unit ORU, and the image reading element CCD. Communication means (not shown) for transferring the received image data to the memory of the image forming apparatus main body IMH.

(About the post-processing device FIN)
The post-processing device FIN is a so-called in-body finisher housed in a U-shaped space formed by the image forming apparatus main body IMH and the scanner device SCM, and its functional configuration can be selected and selected in various cases. Intermediate coupling unit SHM incorporating a curl removing device DCM for removing curl of the sheet to be processed, post-processing unit SPM for receiving sheets from intermediate coupling unit CHM and performing post-processing such as stapling and punching, and post-processed sheets The sheet stacker DET can be moved up and down to sequentially stack and stack sheets that are not bundled or post-processed.

Thereafter, as shown in FIG. 7, the post-processing unit SPM is movably mounted on a pair of left and right moving guides CPM1 / CPM2 supported by the intermediate connecting unit CHM, and the main body of the image forming apparatus is used for jam processing. Can be withdrawn from IMH. Further, as shown in FIG. 8, the rearward movement guide CPM2 of the pair of left and right movement guides is set to have a larger projection amount than the movement guide CPM1 on the other front side by a dimension d, so that the post-processing unit SPM is connected to the intermediate connection unit. When the post-processing apparatus FIN connected and fixed to the CHM is attached to the image forming apparatus main body IMH, it can be easily fitted.

[Sheet conveying device with curl detector]
Next, a curl detection apparatus of the present invention and a sheet conveying apparatus equipped with the apparatus will be described with reference to FIGS. FIG. 9 is an explanatory view of a sheet conveying apparatus provided with the curl detecting device of the present invention, FIG. 10 is a schematic explanatory view of a curl detecting element used in the curl detecting device, and FIG. 11 is an explanatory view of a curl detection state of the curl detecting device. FIG. 12 is an explanatory diagram for explaining a curl detection determination method, and FIG. 13 is an explanatory diagram for explaining a curl removal method based on curl distance measurement data.

(About the sheet transport device SHM)
First, the sheet conveying device SHM equipped with the curl detecting device CDM shown in FIG. 9 will be described. The sheet transport apparatus SHM includes a transport roller pair R1 / R2 on the upstream side in the transport direction and a transport roller pair R3 / R4 on the downstream side in the transport direction, which are arranged at intervals slightly shorter than the minimum size width of the transportable sheet SH, and will be described later. When the curl is detected, the front end of the curled sheet SH in the conveyance direction is not restricted, and an upper and lower conveyance space is formed. The sheet SH between the pair of rollers is conveyed to the conveyance guide G1 / G2 and the conveyance roller on the downstream side in the conveyance direction. The sensor pair SE1 / SE2 that detects the leading edge of the sheet SH in the vicinity of the downstream of the pair R3 / R4, and the sheet surface height of the sheet SH at a position where the sensor pair SE1 / SE2 conveys a predetermined pulse from the position at which the leading edge of the sheet SH is detected. It comprises a curl detection device CDM for measuring the position.

(About the curl detection device CDM)
The curl detection device CDM includes a light emitting means PD1 for irradiating spot light toward the paper surface of the sheet SH, a light receiving means PD2 for receiving reflected light reflected from the paper surface of the sheet SH, and a paper surface of the sheet SH from output data of the light receiving means PD2. And a curl state judging means (CPU) for detecting the amount of curl by capturing the amount of displacement from the reference position.

(About the light receiving means PD2)
In this embodiment, a position detection element PSD as shown in FIG. 10 is used as the light receiving means PD2. This position detection element PSD has both output terminals with respect to the vertical axis (-a to + a) as shown in the figure, as the spot light of the light emitting means PD1 shifts the reflected light irradiation position depending on the vertical position of the sheet SH. The output value (Ia-Ib) of Ia / Ib changes. From the output value (Ia−Ib), the curl state determination means (CPU) captures a value corresponding to the vertical axis (−a to + a) to determine the curl state.

(About the curl state judgment method)
The curl state judging means (CPU) performs curl detection according to the following procedure. The detection method will be described with reference to FIGS.

<Input initial data to determine curl status>
First, in order to determine the curl state shown in FIG. 12, various sheets whose curl state is known in advance are passed through the sheet conveying device SHM, and necessary data values are captured by the curl detection device CDM, and the curl state determination means (CPU). Remember me. Although the figure shows only the state of the lower curl, the state of the upper curl is omitted because it is inverted upside down.

<First detection: distinguishing between upper curl and lower curl>
The leading end of the sheet SH is further conveyed downstream by the conveying amount L1 from the time when the leading end of the sheet SH conveyed downstream by the conveying roller pair R1 / R2 is detected by the sensor pair SE1 / SE2. The position of the leading end of the sheet SH is detected by the curl detection device CDM, and first, it is determined whether the sheet SH is an upper curl or a lower curl, and the displacement (for example, a1 / b1 value) is stored as data. In this way, by grasping the leading end of the sheet SH in the vicinity of the conveying roller pair R1 / R2, the curl direction can be determined without being affected by the degree of waist strength of the sheet SH.

<Second detection: discriminating up and down swell state>
Further, the leading end of the sheet SH is further conveyed downstream by the conveying amount L2 from the time when the leading end of the sheet SH conveyed downstream by the conveying roller pair R1 / R2 is detected by the sensor pair SE1 / SE2. Then, the paper surface of the sheet SH reaching the detection area detected by the curl detection device CDM is detected, and the displacement amount (for example, a2 / b2 value) in that state is stored as data. In this way, the undulation state of the sheet SH can be detected by detecting the displacement of the sheet SH around the center and detecting the change in the gradient of the paper surface.

<Third detection: Determining the degree of deflection>
Further, the leading end of the sheet SH is further conveyed downstream by the conveying amount L3 from the time point when the leading end of the sheet SH conveyed downstream by the conveying roller pair R1 / R2 is detected by the sensor pair SE1 / SE2. The paper surface of the sheet SH reaching the detection area detected by the curl detection device CDM is detected, and the displacement amount (for example, a3 / b3 value) in that state is stored as data. In this way, in a state where the conveying roller pair R1 / R2 grips the trailing end of the sheet SH, the amount of bending is affected by the strength of the waist of the sheet SH by bending due to the weight of the sheet SH itself. It can be judged from.

<Determination of curl state determination means (CPU)>
The curl state determination means (CPU) compares the first to third distance measurement data with the initial data, and determines various curl states as shown in FIG.

[Curl correction]
Next, the curl correction shown in FIG. 13 will be described. In the figure, the decurler DCM is configured in the intermediate connection unit CHM described above.

(About the decurler DCM)
The decurling device DCM is stretched between the upstream-side transport roller pair R5 / R6 and the downstream-side transport roller pair R7 / R8 arranged in the front and rear of the transport direction, and presses and sandwiches the sheet SH with each other. A pair of upper and lower belts VE1 / VE2 to be conveyed and a sheet supported by a central portion of the pair of upper and lower belts VE1 / VE2 so as to be movable up and down, and the pair of upper and lower belts VE1 / VE2 being detected by a curl state determining means (CPU) It consists of a pair of upper and lower curl removal rollers DC1 / DC2 that form a curled state opposite to the curled state of SH.

(About the curl removal method)
Therefore, the curl removal method will be described with reference to FIG. Depending on the curl state of the sheet SH determined by the curl state determination means (CPU), the pair of upper and lower curl removal rollers DC1 / DC2 are paired up and down so as to be opposite to the curl state of the discharged sheet SH as shown in the figure. The belts VE1 / VE2 are bent. The curl is removed by the sheet SH passing through the pair of upper and lower curved belts VE1 / VE2.

In the embodiment described above, two or more paper surface positions of a sheet passing through a predetermined position of the sheet paper surface detection sensor are detected, and the distance measurement information of the two or more locations is output as the distance measurement information of the sheet. However, the paper surface of the sheets passing through the predetermined position may be continuously detected. In this case, the curl state can be detected more accurately.

In the above embodiment, the curl detection device CDM detects three predetermined positions of the sheet SH. However, the curl detection accuracy is increased by increasing the predetermined position and continuously detecting the paper surface of the sheet SH. Needless to say, it can be improved significantly.

R1, R2 Conveying means SE Sheet paper surface detection sensor (ranging sensor)
SE1 Light emission source SE2 Light receiving sensor PSD Position Sensitive Detector
CPU curl state judging means

Claims (12)

A distance measuring means disposed opposite to the sheet surface of the sheet conveyed and passed through a predetermined position, and measuring the distance to the sheet surface of the sheet;
Curling state determination means for determining the curl state of the sheet from distance measurement information of the distance measuring means,
The sheet curl detection apparatus is characterized in that the distance measuring unit measures at least two positions on the front and back of a sheet passing in a predetermined position. 2. The sheet curl according to claim 1, wherein the curl state determination unit determines the curl state of the sheet by comparing distance measurement information of the distance measurement unit with basic information stored in advance. Detection device. 2. The sheet curl detection apparatus according to claim 1, wherein two or more distance measuring units are arranged in the sheet width direction and simultaneously capture a curl state in the sheet conveyance direction and width direction. The distance measuring means measures a distance between three positions, that is, a first sheet surface position of a sheet front end portion passing through a predetermined position, a second sheet surface position of a sheet central portion, and a third sheet surface position of a sheet rear end portion. The sheet curl detecting apparatus according to claim 1 or 3, wherein The distance measurement information of the first paper surface position detects characteristic data for determining upper curl and lower curl, and the distance measurement information of the second paper surface position detects characteristic data for determining wavy curl, 5. The sheet curl detection apparatus according to claim 4, wherein the distance measurement information of the third paper surface position is obtained by detecting characteristic data for determining a degree of sheet deflection. The basic information conveys a sheet for which a necessary data value is found among a data value indicating the curl degree of the upper curl and the lower curl, a data value indicating the degree of waviness, and a data value indicating the degree of sheet deflection. 2. The sheet curl detecting apparatus according to claim 1, wherein each distance of each of the first, second, and third paper surface positions is detected and the distance measurement data is stored. 5. The sheet curl detection apparatus according to claim 1, wherein the distance measuring unit is a non-contact type distance measuring sensor. The distance measuring sensor includes a light emitting source for irradiating a sheet passing through the predetermined position with a spot light;
A light receiving sensor that captures reflected light emitted from the light source and reflected from the sheet surface;
8. The sheet curl detection apparatus according to claim 7, comprising: 9. The sheet curl detection apparatus according to claim 8, wherein the light receiving sensor includes a position sensitive detector. A distance measuring unit arranged to face the sheet surface of the sheet conveyed and passed through a predetermined position, and a curl for determining the curl state of the sheet from the distance measurement information of the distance measuring unit A state determination unit, and the distance measurement unit is a sheet curl detection device that measures a distance of at least two places on the front and back of the sheet in the conveyance direction of a sheet passing through a predetermined position,
A sheet for which a necessary data value among the data value indicating the curl degree of the upper curl and the lower curl, the data value indicating the degree of undulation, and the data value indicating the degree of sheet deflection is conveyed and passed through a predetermined position. A first step of measuring at least two of the first, second, and third paper surface positions before and after the conveyance direction and storing the distance measurement data as basic information;
A second step of conveying the curl measurement sheet, passing the predetermined position, and detecting at least two or more of the first, second, and third paper surface positions of the sheet as ranging information;
A third step of comparing the basic information stored in the first step with the distance measurement information of the curl measurement sheet detected in the second step, and determining the curl state of the curl measurement sheet;
A curl detection method for a sheet comprising: A sheet curl detection device according to claim 1, which is disposed in a sheet conveyance path;
A curl correcting unit that corrects curl of a sheet conveyed based on curl information of a curl state determining unit of the curl detecting device;
A sheet conveying apparatus comprising: 12. The sheet conveying apparatus according to claim 11, wherein the curl correcting unit includes a decurling device that receives curl information from the curl state determining unit and performs reverse curling on the sheet.