JP5531779B2 - Image forming apparatus and curl correction method - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image by melting toner in a copying machine, a printer, a multifunction machine, or the like using an electrophotographic technology, and more specifically, a toner image is carried on a pressure contact portion of a pressure contact member. Image forming apparatus including a fixing device that passes a transfer material such as paper and melts the toner image by heat and fixes the image onto the transfer material, and a curl correction device that corrects deformation of the transfer material such as curl, and curl correction Regarding the method.

  Conventionally, in an image forming apparatus using an electrophotographic method, a charging device holds charges on the surface of an image carrier, and laser light or LED (Light Emitting Diode) light is irradiated from a light irradiation device according to image information. Then, a latent image is formed on the image bearing member, the latent image is visualized with toner of a developing device, the toner image is transferred to a transfer belt by a transfer device, and then transferred to paper. Next, the toner image formed on the paper is heated between the fixing member and the pressure member in the fixing device to be fixed on the recording medium.

  In such an electrophotographic fixing device, the paper that has come out of the pressure contact portion between the fixing member and the pressure member is deprived of humidity due to heating and shrinks due to the dehumidification. In such a fixing device, there is a case where there is a heat source on the heating roller side, but there is no heat source on the pressure side or the output of the heat source is small. The difference will occur. Due to this temperature difference, a difference occurs in how the humidity on the front and back sides of the paper is deprived, thus causing a difference in shrinkage, and curling occurs depending on this difference. If the curled paper is discharged from the fixing device as it is, paper jams in the transport path after fixing, bulkiness on the storage in the paper discharge unit, and the like are likely to occur.

  Further, in the fixing unit that pinches the paper, rollers or belts having different hardnesses are in contact with each other and deformed in order to secure a contact area. As a result, sufficient melting of the toner is performed, but as a side effect, the paper is curled along the deformation of the contact portion. Conventionally, a curl correcting device is sometimes used to correct the curl that occurs during such fixing.

  As a curl correction device, for example, a roll nip type device including an elastic roll and a pressure roll that rotates while pressing the elastic roll to form a curved nip conveying portion is known. In addition, a belt nip type belt comprising a belt that is wound around a belt support roll and rotated, and a portion that becomes the support roll of the belt is pressed to form a curved nip conveying portion, and is composed of a rotating pressure roll. Are known. In any of the above-described curl correction apparatuses, the direction in which the paper after fixing is passed through the curved nip conveyance unit between the elastic roll or the belt and the pressing roll and the paper is curled is defined as By curving and deforming temporarily in the opposite direction, the curl-free state is corrected.

  In such a curl correction apparatus, the curl state generated after fixing varies depending on the type of transfer paper, the density of an image formed on the paper, the environmental humidity, and the like. For this reason, conventionally, the amount of curl correction to be corrected by the curl correction device is adjusted according to predetermined parameters such as the type of transfer paper and the image density.

  For example, Japanese Patent Laid-Open No. 2002-316761 (Patent Document 1) calculates a correction amount according to the surrounding environment and the type of paper for the purpose of performing accurate curl correction with respect to environmental changes and paper types. An image forming apparatus is disclosed. More specifically, in the technique of Patent Document 1, environmental information around the printing unit is acquired by the environmental information input unit, and the curving correction amount of the medium by the curl correcting unit is calculated based on the acquired environmental information. . This makes it possible to perform curl correction with a relatively accurate curvature correction amount even when there are environmental fluctuations such as changes in ambient temperature and humidity. In the technique of Patent Document 1, the winding angle of the paper passing through the curl correction roller can be adjusted depending on the type of paper that has been input in advance.

  Furthermore, the patent No. 4009051 (Patent Document 2) can correct the curl with certainty, eliminates the complexity of the structure used for that purpose, prevents the cost increase, and further occurs in the used sheet. For the purpose of correcting the curl regardless of the degree of curling, the roller positioned upstream in the paper transport direction can change the winding angle according to the thickness of the sheet or the curl amount of the sheet The curl correcting apparatus is characterized in that the winding angle can be set in a plurality of stages.

  Japanese Patent Laid-Open No. 2007-328054 (Patent Document 3) is fixed by a fixing device and a first dehumidifying suppression means for suppressing dehumidification from one surface of a sheet fixed by the fixing device. And a second dehumidification suppression unit that suppresses dehumidification from the other surface of the sheet 2, and the first and second dehumidification suppression units correct the curl of the sheet generated by the fixing device. Disclosed is a sheet correction apparatus characterized by varying the degree of dehumidification suppression.

  Further, Japanese Patent Laid-Open No. 2006-208509 (Patent Document 4) has a good fixability and a paper curl after fixing by performing control to correct the fixing temperature by detecting the environment over time in addition to during standby. In order to obtain a stable fixing property, the fixing device has a plurality of temperature detecting means, and the image forming apparatus has a plurality of detecting means for detecting temperature and humidity. An image forming apparatus is disclosed that performs temperature correction to change the target control temperature of the fixing device to a predetermined value in accordance with the temperature or humidity detected by the detecting means.

  However, in the environment around the actual fixing device, paper heated to 100 ° C. or more is passed, so the moisture of the paper evaporates at the time of passing, and a state different from the vicinity of the image forming unit is formed. Has been. Further, the temperature of the fixing roller or fixing belt of the fixing device and the temperature of the pressure roller or pressure belt facing each other are not always constant, and fluctuate immediately after rising in the morning or during continuous paper feeding. Such a change in the fixing state is difficult to grasp from temperature / humidity measurement values in the vicinity of the image forming unit and information on only the paper type.

  Therefore, in the conventional techniques disclosed in Patent Document 1 and Patent Document 2, even if curl correction is controlled in accordance with temperature / humidity measurement values and paper type information in the vicinity of the image forming unit, it is uncertain. End up. In the technique of Patent Document 3 described above, the curling state changes immediately after startup in the morning or during continuous paper feeding, and the curling state varies depending on the paper type. It was not sufficient in that it could not cope sufficiently with the number of paper sheets and the like, resulting in uncertain curl correction. The prior art disclosed in Japanese Patent Laid-Open No. 2004-228561 is a target for a fixing device that is closely related to a temperature difference between an internal temperature of an image forming apparatus and a temperature of a portion close to the outside air, and an internal or external humidity value. The purpose is to fix the image without curling by correcting the temperature, but it does not correct the generated curl.

  In the fixing device, the heater for heating the fixing roller or belt is energized, and then the opposite roller or belt is warmed by heat conduction and radiation. However, when the image forming apparatus is started up, the opposite roller or belt is heated. Instead, a surface temperature difference occurs between the fixing roller or belt side of the image surface and the roller or belt on the opposite side, and this temperature difference is different from that in the state after sufficiently warming. . Further, even after the paper is sufficiently warmed, if the paper passes continuously, the heat of the fixing device is taken away by the paper, and there is no particular heating means, or the pressure roller on the opposite side where the output is not sufficient. If it does, the temperature will drop.

  Hereinafter, a curl generation mechanism when there is a temperature difference between the fixing roller and the pressure roller will be described with reference to FIG. In FIG. 18A, in the nip portion between the heating roller and the pressure roller, since the heating roller is at a temperature exceeding 100 ° C., the water content contained in the paper is vaporized to become water vapor. However, since both surfaces are closed by the heating roller and the pressure roller, moisture cannot be evaporated to the outside and is discharged into the gap between the fibers in the paper. At this time, when the temperature on the pressure side is low and does not reach 100 ° C., the air pressure is high in the gap in the paper near the heating side, and the air pressure is low on the low temperature side. Due to the pressure change inside the void, the water vapor density on the low temperature side becomes higher than that on the high temperature side.

  In FIG. 18B showing a state where the paper is discharged from the fixing nip, if the temperature on the pressure side is about 100 ° C. and the water vapor can be sufficiently evaporated to the outside, a large amount of water vapor is generated from the pressure side. It will be transpired. FIG. 18D shows the relationship between the moisture evaporation amount of paper and the shrinkage amount, but the moisture evaporation amount of paper and the shrinkage amount of paper are approximately proportional to each other. Since the roller side contracts greatly, curling occurs on the pressure roller side as shown in FIG. In fact, immediately after the fixing nip, if there is a thermohygrometer with responsiveness that can sense moisture evaporating from the paper in the vicinity of the front and back of the paper, and if curling occurs, It was found that the more evaporated side curls inward, and the greater the difference in temperature and humidity, the greater the curl. In addition, when the temperature on the heating side and the pressure side is high as described above, moisture content is unevenly distributed due to internal moisture movement, so that the curl amount becomes larger.

  In other words, in the prior art, depending on the operating conditions of the image forming apparatus, the curl suppression effect may be lower than the actual curl amount, or if the suppression effect is adjusted higher, the curl may be excessive and curl to the opposite side. Such a problem occurs, and it is not possible to sufficiently cope with a change in the fixing state that changes according to the operation state. Further, in order to predict the curl amount, the curl calculation data is necessary. However, the paper type cannot be specified, and appropriate curl calculation data may not be obtained. The prior art could not cope. Even if the type of paper can be identified, curl calculation data unique to the paper is required in order to be able to predict the curl amount with high accuracy. For example, even in the existing types, paper on the market does not always have a certain characteristic, so there is a possibility that the current characteristic is different from the past data. Also, considering the correspondence of new products, the curl calculation data must be updated. However, updating the data to an image device that is already in operation in the market has a lot of labor and labor.

  The present invention has been made in view of the above-mentioned problems in the prior art, and the present invention affects the fixing state such as the temperature state in the fixing device and the transfer material characteristics accompanying the change in the operation state of the image forming apparatus. It is an object of the present invention to provide an image forming apparatus and a curl correction method capable of realizing an appropriate and fine curl correction in response to a change in a factor that gives a sharpness. Another object of the present invention is to provide an image forming apparatus and a curl capable of realizing curl correction with sufficient accuracy even when the type of transfer material cannot be specified or the characteristics of the transfer material fluctuate. It is to provide a correction method.

  As a result of intensive studies in view of the above problems, the present inventors have determined that the size of the fixing curl is not simply determined by the setting environment of the image forming apparatus and the type of paper, Specifically, the mechanism related to humidity as described above immediately after the start of printing when the temperature inside the image forming apparatus is substantially the same as the temperature, greatly influenced by the temperature difference between the front and back of the transfer material at the fixing nip. It has been found that a large curl is generated and the present invention has been achieved. By considering the above mechanism, it is possible to finely correct the curl by taking into account fluctuations in the factors affecting the fixing state, such as the temperature / humidity state of the fixing device and the transfer material characteristics, depending on the operating status of the image forming apparatus. It has been found important to control the device.

  In the present invention, in order to solve the above problems, in an image forming apparatus including a fixing device and a curl correcting device, at least of the transfer material that is provided in the transfer path of the transfer material in the image forming device and is conveyed. A first detection sensor that detects and outputs humidity near one surface; and at least one physical quantity related to one or both of temperature and humidity near at least one surface of the transfer material that has passed through the pressure contact portion of the fixing device. And second detection sensor means for detecting and outputting the above. Then, a curl estimation amount is calculated from the humidity output value output from the first detection sensor means and the output value of at least one physical quantity output from the second detection sensor means, and the curl estimation amount is associated with the curl estimation amount. Set the control value and control the curling device.

  According to the above configuration, at least one physical quantity related to one or both of humidity near at least one surface of the transfer material and temperature and humidity near at least one surface of the transfer material that has passed through the pressure contact portion. By measuring the physical quantity of the factor that directly affects the curl generated in the machine, the state of curl generation is estimated, and the environmental fluctuations inside the machine, changes in the fixing conditions in the fixing device, and the transfer material The amount of curl that can be affected by various factors such as thickness and moisture absorption state can be estimated with high accuracy, and as a result, highly accurate curl correction can be realized.

  Further, according to the present invention, it is possible to read the transfer material information that characterizes the shrinkage characteristics of the used transfer material input to the image forming apparatus, and obtain the estimated curl amount according to the transfer material information. The transfer material information that characterizes the shrinkage characteristics of the transfer material can include a value that indicates the thickness of the transfer material, a value that identifies the classification of the transfer material, or a value that identifies a unique type of transfer material. In the present invention, a function for calculating a curl estimation amount from an output value of humidity output from the first detection sensor means and an output value (for example) of at least one physical quantity, or output from the first detection sensor means. The curl estimation amount can be obtained by using a table that associates the curl estimation value with the output value of the humidity and the output value of at least one physical quantity.

  Furthermore, according to the present invention, it is possible to perform update processing of a function parameter or table for obtaining a curl estimation amount by communicating with a server device connected via a network. According to the above configuration, it is possible to cope with a case where a new transfer material is used or a change in characteristics over time of a circulating transfer material, and greatly reduces the work burden on the administrator at that time. It becomes possible.

  Further, in the present invention, the first detection sensor means can be disposed in the vicinity of the pressure contact portion of the fixing device, and detects the humidity near the first surface of the transfer material that has passed through the pressure contact portion of the fixing device. (For example, sensor 41a) can be provided. The second detection sensor means can be disposed opposite the first detection means, and detects the humidity near the second surface of the transfer material that has passed through the pressure contact portion of the fixing device as one of the physical quantities. A sensor (eg, sensor 41b) may be provided. In this case, the curl estimation amount can be obtained by using the sum and difference of the humidity output values on the first surface side and the second surface side.

  Further, in the present invention, the first detection sensor means includes a temperature sensor (for example, a sensor 41a) that detects the temperature in the vicinity of the first surface of the transfer material, and the second detection sensor means further includes the second surface of the transfer material. A temperature sensor (for example, a sensor 41b) that detects a temperature in the vicinity as one of the physical quantities can be provided. In this case, instead of the difference between the output values of the humidity near the first surface and the second surface of the transfer material, the estimated curl amount is obtained using the difference between the output values of the temperatures near the first surface and the second surface. be able to.

  Further, in the present invention, the first detection sensor means can be disposed in the vicinity of the pressure contact portion of the fixing device, and one of the vicinity of the first surface and the second surface of the transfer material that has passed through the pressure contact portion of the fixing device, or At least one humidity sensor (for example, sensors 41a and 41b) that detects both humidity levels may be provided. Further, the second detection sensor means may include two temperature sensors (for example, sensors 36 and 39) that detect the surface temperatures of both the pressure member and the fixing heating member constituting the pressure contact portion as at least one physical quantity. it can. In this case, the type of transfer material is determined using a function or table that defines the correlation of the estimated curl amount of the transfer material with respect to at least three variables including two surface temperatures and at least one humidity defined for each type of transfer material. Correspondingly, the curl estimation amount can be obtained.

  According to the above configuration, for example, when the type of transfer material is unknown, the standard or average data is used, and when only the thickness or classification of the transfer material is known, the thickness range or It can be handled by using standard or average data of classification, and when specific types (brands) of transfer materials are known, it is possible to meticulously deal with specific types of data. It becomes.

  In the present invention, the first detection sensor means (for example, the sensor 402) can be installed upstream of the transfer portion of the transport path, and the second detection sensor means includes a pressure member and a fixing member that constitute the pressure contact portion, respectively. Two temperature sensors (sensors 36, 39) that detect the surface temperature of both of the heating members as at least one physical quantity may be included. In this case, the curl estimation amount of the transfer material with respect to the moisture content of the transfer material converted from the humidity output value output from the first detection sensor means and the difference between the output values of the surface temperature of the pressure member and the fixing heating member The curl estimator can be determined using a function or table that defines the correlation of

  Further, according to the present invention, there is provided a curl correction method executed by an image forming apparatus including a fixing device and a curl correction device. In the curl correction method of the present invention, the first detection sensor means provided in the transfer material conveyance path in the image forming apparatus detects and outputs the humidity in the vicinity of at least one surface of the transferred transfer material. A step of detecting and outputting at least one physical quantity related to one or both of temperature and humidity in the vicinity of at least one surface of the transfer material that has passed through the pressure contact portion of the fixing device; and A calculating means for calculating a curl estimation amount from an output value of humidity output from the first detection sensor means and an output value of at least one physical quantity output from the second detection sensor means; Setting a control value corresponding to the amount and controlling the curling device.

1 is a diagram illustrating a schematic configuration of a multifunction machine according to a first embodiment. FIG. 3 is a diagram illustrating a schematic configuration around a fixing device and a curl correction device in the multifunction machine according to the first embodiment. FIG. 3 is a diagram illustrating an example of sensor arrangement in the multifunction peripheral according to the first embodiment. 1 is a diagram illustrating a hardware configuration of an image forming system including a multifunction machine according to a first embodiment. 1 is a functional block diagram of a multifunction machine and a server device according to a first embodiment. 6 is a flowchart illustrating a curl correction control operation executed by the multifunction machine according to the first embodiment. 5 is a flowchart illustrating update processing executed by the multifunction peripheral according to the first embodiment. FIG. 4A is a graph showing the time change of humidity output of the first sensor and the second sensor, and FIG. 4B is a graph plotting the curl amount against the humidity difference between the front surface and the back surface of the transfer material. The figure which illustrates the data structure of the data for curl calculation. The graph which plotted the distortion amount of the transfer material with respect to the humidity of the transfer material vicinity. The figure which illustrates the data structure of the data for curl calculation which can be used in 2nd Embodiment. The figure which illustrates the test device which tests the distortion amount of a transfer material. FIG. 10 is a diagram illustrating a schematic configuration of a multifunction machine according to a third embodiment. The figure which shows the structure of the thickness sensor which measures the thickness of the transfer material of 3rd Embodiment. FIG. 9 is a functional block diagram of a multifunction machine according to a third embodiment. 10 is a flowchart illustrating a curl correction control operation executed by the multifunction machine according to the third embodiment. The figure which illustrates the data structure of the data for curl calculation of 3rd Embodiment. The figure which shows the production | generation mechanism of a curl when there exists a temperature difference of a fixing roller and a pressure roller.

  Hereinafter, although embodiment of this invention is described, embodiment of this invention is not limited to the following embodiment. In the embodiment described below, a multifunction machine having a color printing function will be described as an example of an image forming apparatus.

  FIG. 1 shows a schematic configuration of a multifunction machine according to the first embodiment. In the multifunction machine 1 shown in FIG. 1, for each color of black (K), magenta (M), cyan (C), and yellow (Y), the photosensitive drum 3 and the charging that charges the photosensitive drum 3 are charged. A roller 4, a light irradiation device 6 such as a laser diode or LED, a polygon mirror 5 that is driven to rotate at a high speed and a constant speed by a motor, and scans a light beam in the main scanning direction of the photosensitive drum 3, and a developer are held. A developing device 7 is arranged along the intermediate transfer belt 2. The MFP 1 shown in FIG. 1 illustrates an embodiment that employs a so-called tandem configuration.

  In the image forming process, first, negative charges are applied to the photosensitive drums 3a, 3b, 3c, and 3d by the charging rollers 4a, 4b, 4c, and 4d, respectively, so that they are uniformly charged. Light beams are output from the light irradiation devices 6a, 6b, 6c, and 6d in accordance with the written image signal, and charged photosensitive drums 3a, 3b, and 3c through an optical system including the polygon mirrors 5a, 5b, 5c, and 5d. , 3d is irradiated, and a potential distribution according to the presence or absence of light beam irradiation and the exposure amount is written.

  The electrostatic latent image to be written is black (K), magenta (M), cyan (C) and yellow (Y), which are toner primary colors generated after processing data transmitted from a scanner or personal computer. It is formed by controlling the on / off of the light beam according to the signal. The formed electrostatic latent images are conveyed in the developing devices 7a, 7b, 7c, and 7d directions as the photosensitive drums 3a, 3b, 3c, and 3d rotate, and are developed with toner. Then, a toner image corresponding to the writing signal is formed on the photosensitive drum 3 and carried.

  On the other hand, an intermediate transfer belt 2 stretched around rollers 21 and 22 is disposed as an intermediate transfer member below the photosensitive drums 3a, 3b, 3c, and 3d. The intermediate transfer belt 2 is rotated in the direction of the arrow shown in the figure, and the rollers 9a, 9b, 9c, and 9d are in contact with the back side thereof, and a primary bias is applied by the power supplies 31a, 31b, 31c, and 31d connected thereto, respectively. ing. The toner image is conveyed to the intermediate transfer belt 2 side as the photosensitive drum 3 rotates, and is transferred onto the intermediate transfer belt 2 at a position where the photosensitive drum 3 and the intermediate transfer belt 2 are in contact with each other by the roller 9. The toner images of the respective colors are superimposed at the same position, and a toner image of a multicolor image is formed on the intermediate transfer belt 2. After the toner image transfer on the photosensitive drum 3 is completed, the toner remaining on the outer peripheral surface is wiped off by the photosensitive cleaner, and then the charge is removed by the static eliminator and supplied to the next image forming process.

  The multi-color toner image transferred onto the intermediate transfer belt 2 is conveyed toward the transfer roller 23 of the secondary transfer portion. On the other hand, a transfer material, which is a sheet-like member such as paper set in the paper feed cassette 51 or the paper feed cassette 52, is fed toward the transfer roller 23 at a set timing. The transfer material is sent out at an appropriate timing in accordance with image writing.

  Charge is supplied to the transfer roller 23 from the power source 25, and together with the roller 14, the toner images on the intermediate transfer belt 2 are transferred to the fed transfer material in a batch. The transfer material is conveyed to a position in contact with the intermediate transfer belt 2 and receives a multicolor toner image. The transfer material on which the multicolor toner image is formed is supplied to the nip portion between the heat fixing roller 30 and the pressure roller 37 of the heated fixing device. Then, the transfer material and the multicolor toner image are heated and pressed, and the held toner image is fixed on the transfer material.

  The transfer material after fixing is subjected to curl correction by the curl correction device 40 and then discharged onto the discharge tray 50 by a discharge roller along a predetermined conveyance path. On the other hand, the intermediate transfer belt 2 after transferring the multicolor toner image is supplied to the next image forming process after the remaining toner agent is removed by a cleaning blade or the like. In the present embodiment, description will be made assuming that roller-shaped members such as the heat-fixing roller 30 and the pressure roller 37 are used as the fixing member and the pressure member, but in other embodiments, the roller-shaped member is used instead. The belt-shaped member can also be used.

  Hereinafter, the details of the fixing device and the curl correcting device will be described with reference to FIG. FIG. 2 shows a schematic configuration of the periphery of the fixing device and the curl correction device in the multifunction machine of the first embodiment. As shown in FIG. 2, the fixing device of the present embodiment includes a heat fixing roller 30 and a pressure roller 37 facing the heat fixing roller 30. In the heat fixing roller 30, a resin layer 30b such as a fluororesin (PFA) having heat resistance and excellent releasability is formed on the peripheral surface of the pipe-shaped metal core 30a. And the heater 34 is provided inside the pipe-shaped metal core 30a, and the temperature sensor 36 is arrange | positioned in contact with the surrounding surface of the resin layer 30b.

  As the heater 34, any one such as a halogen heater or an electromagnetic induction heater can be used. The heat fixing roller 30 and the pressure roller 37 rotate in a direction indicated by an arrow in FIG. 2, and convey and pass the transfer material P to the nip portion 35 where they are in pressure contact. An inlet guide 33 is provided on the transfer material inlet side of the nip portion 35 to direct the front end of the transfer material toward the nip portion 35.

  In the fixing device described above, the transfer material P after image transfer is guided by the entrance guide 33 and passed through the nip portion 35 between the heat fixing roller 30 and the pressure roller 37, and the transferred multicolor toner image is subjected to heat and pressure. To fix on the transfer material P. At this time, the temperature sensor 36 measures the surface temperature of the heat-fixing roller 30 and appropriately controls the temperature in accordance with the measurement signal, and controls the energization / interruption of the heater 34 or the current value to thereby control the heat-fixing roller 30. The surface temperature is kept constant. The temperature range of the heat fixing roller 30 is set to about 100 ° C. to 180 ° C., and is generally set to about 160 ° C. Furthermore, a temperature sensor can be installed in contact with the surface of the pressure roller 37 according to the specifications of the fixing device. In the fixing device of the present embodiment, a temperature sensor 39 is provided on the pressure roller 37 side, and pressure is applied. The surface temperature of the roller 37 can be measured.

  As shown in FIG. 2, a first sensor 41a and a second sensor 41b are installed on the downstream side of the nip portion 35 of the fixing device in the passing direction of the transfer material so as to face the first sensor 41a. The sensors 41a and 41b of the present embodiment are preferably configured as temperature and humidity sensors and have a response performance of 1 second or less. From the viewpoint of improving the printing throughput, the response performance of 0.1 second or less. It is more preferable to use one having

  The part of the temperature / humidity sensor as a humidity sensor is, for example, a capacitance type humidity that forms a capacitor using a polymer film as a dielectric, and converts moisture absorption and desorption into an electrical signal as a change in capacitance. An electrode is composed of a high-sensitivity polymer material and a stable metal on a sensor or a substrate, and an electric resistance humidity sensor that converts a change in resistance due to moisture at the electrode into an electric signal is used. be able to. As the temperature sensor of the temperature / humidity sensor, a thermistor, a band gap type temperature sensor, or the like can be used, and other principles and configurations may be used as long as they have similar performance. In the embodiment to be described, the sensors 41a and 41b are configured as a temperature and humidity sensor having a function of detecting both humidity and temperature. However, in other embodiments, the sensor detects only one of humidity and temperature. You may comprise as.

  FIG. 3 shows an example of sensor arrangement in the multi-function peripheral of this embodiment. As shown in FIG. 3, these sensors 41 a and 41 b are arranged at a predetermined distance L from the exit of the nip portion 35 between the heat fixing roller 30 and the pressure roller 37. The distance L can be 1 mm to 50 mm, and is more preferably 5 mm to 20 mm from the viewpoint of stably detecting the humidity and temperature in the vicinity of the front and back surfaces of the transfer material with high accuracy. Further, as shown in FIG. 3, the sensors 41a and 41b are arranged so as to be separated by a predetermined distance H from the respective positions of the front surface and the back surface of the passing transfer material. The distance H can be within 10 mm, and is more preferably 0.1 mm to 1 mm from the viewpoint of accurately detecting the humidity and temperature in the vicinity of the front and back surfaces of the transfer material.

  Referring to FIG. 2 again, the transfer material P that has passed through the nip portion 35 between the heat fixing roller 30 and the pressure roller 37 further passes between the first sensor 41a and the second sensor 41b facing each other. Since the transfer material P that has passed through the fixing device is heated to about 100 ° C. to 180 ° C. by the heat fixing roller 30, moisture contained in the transfer material P is released as vapor into the air from both sides. The sensors 41 a and 41 b capture these vapors, detect the temperature and humidity of the vapors near the front surface and the back surface of the transfer material P, and output them to a CPU (Central Processing Unit) 46.

  FIG. 8A shows the change over time in the humidity output of the first sensor 41a and the second sensor 41b. As shown in FIG. 8A, the outputs of the sensors 41a and 41b are such that the humidity output of both the sensors 41a and 41b increases and the output of the second sensor 41b is high in the time region in which the transfer material P passes, Data such that the first sensor 41a is lowered is measured. When such data is obtained, curling with the second sensor 41b side, which is the side with the larger evaporation amount, inside occurs on the transfer material P.

  The CPU 46 of the multifunction device 1 of the present embodiment acquires both or one of the temperature output value and the humidity output value of the first sensor 41a and the second sensor 41b in the transfer region of the transfer material P, and the curl amount of the transfer material P Is estimated (hereinafter referred to as a curl estimation amount). The output value is sampled in synchronization with the timing when the transfer material P passes between the sensors 41. In the case where the sensors 41a and 41b have response performance that allows multiple sampling during the passage period, an average value of a plurality of sampling points can be used. Note that the timing at which the transfer material P passes between the sensors 41 can be measured from the timing of paper feeding, or a paper passing sensor or the like may be used.

  The CPU 46 is also connected to the temperature sensor 36 on the heat fixing roller 30 side and the temperature sensor 39 on the pressure roller 37 side, and can acquire these temperature output values. Details of the curl estimation amount calculation method will be described later. The control device 47 controls the operation of the curl correction device 40 using a control value according to the calculated curl estimation amount. The curl correction device 40 includes an endless belt 45 that constitutes a transfer path of the transfer material P, a transfer driving roller 42 that is opposed to and abuts against the expansion surface of the endless belt 45, and rotates in a direction corresponding to the transfer direction of the transfer material. A spring 43 and a cam 44 are included.

  The curl correcting device 40 drives the cam 44 under the control of the control device 47 and applies a force by the spring 43 to correct the curl generated on the transfer material. The winding angle can be changed. Thereby, the curl correction according to the estimated curl amount is performed on the transfer material P. The curl correction device 40 is not limited to the illustrated embodiment, and any configuration of the curl correction device can be used as long as a predetermined amount of curl correction can be controlled.

  Hereinafter, a hardware configuration of an image forming system including the multifunction machine 1 according to the present embodiment will be described. FIG. 4 shows a hardware configuration 100 of an image forming system including the multifunction peripheral of this embodiment. As shown in FIG. 4, the MFP 110 according to the present embodiment includes a CPU 112 that controls image forming operations such as image formation and transfer material transfer, and an operation of the curl correction device 40, a ROM (Read Only Memory) 114, A random access memory (RAM) 116 and a non-volatile RAM (NV-RAM) 118 are included.

  The ROM 114 stores a basic input / output system (BIOS) and the like. The RAM 116 provides an execution space for the CPU 112. The NV-RAM 118 stores system setting information, curl calculation data for calculating a curl estimation amount to be described later, control value calculation data for adjusting the curl correction device 40 according to the curl estimation amount, and the like.

  Further, the multifunction device 110 connects the display device 120 and the input device 122 such as an operation panel, the printer 124 for performing the image forming operation, the scanner 126 for performing the image reading operation, and the multifunction device 110 to the network 130. And a network interface card (NIC) 128.

  4 reads out a program (not shown) stored in a storage device such as a ROM 114, NV-RAM 118 or SD card (not shown), and provides a memory of a RAM 116 that provides a work area for the CPU 112. Each functional unit and each process to be described later are realized by expanding the area.

  The network 130 is connected using a LAN (Local Area Network), a VPN (Virtual Private Network), or a dedicated line using a transaction protocol such as Ethernet (registered trademark) or TCP / IP (Transmission Control Protocol / Internet Protocol). WAN (Wide Area Network) or the like. However, the configuration of the network 130 is not particularly limited, and may include the Internet connected via a router (not shown), and may be configured as a wired or wireless network, or a mixed network thereof. it can.

  FIG. 4 further shows the hardware configuration of the server apparatus 150 of the present embodiment, and the server apparatus 150 is connected to the network 130. The server device 150 of this embodiment centrally manages curl calculation data for calculating an estimated curl amount according to the type of transfer material (including various types of products supplied from each supply source). In addition, a server function for appropriately transmitting update data for curl calculation data is provided in response to a request from the multifunction machine via the network 130.

  The server device 150 is configured as a computer device such as a personal computer, a workstation, a blade server, or a multifunction device having a server function, and includes a CPU 152, a ROM 154, a RAM 156, a display device 158 such as a display device, and an input device such as a mouse and a keyboard. 160, NIC 162, and HDD 164. As a result, a server function for providing update data of the curl calculation data described above is realized.

  FIG. 5 shows functional blocks of the multifunction peripheral and the server device of the present embodiment. As shown in FIG. 5, the functional block 200 of the multifunction machine includes a curl amount calculation unit 202, a curl correction control value determination unit 204, a curl correction control unit 206, and an input unit 216. The input unit 216 receives designation of the type of transfer material currently set in the paper feed cassettes 51 and 52 from the operator, and stores it as an appropriate storage area such as the RAM 116 or the NV-RAM 118 as the transfer material information 214.

  The transfer material information 214 holds a type identification value that identifies the type of transfer material for each paper feed cassette. This type identification value characterizes the transfer material of the paper feed set, and the value specified as the type identification value is a value indicating that the type of transfer material is unknown, and a thickness specifying the thickness of the transfer material. It can include a classification value indicating the classification of the transfer material, such as a value, fine paper, recycled paper, semi-glossy paper, glossy paper, matte paper. In a more preferred embodiment, the value specified as the type identification value includes an identification value (part number or series number) for identifying a specific type (brand) of transfer material including differences in supply sources. Also good.

  The curl amount calculation unit 202 appropriately acquires output values from the first sensor 41a, the second sensor 41b, the temperature sensor 36 on the heating and fixing roller 30 side, and the temperature sensor 39 on the pressure roller 37 side, and transfers the transfer material information 214. Read out and calculate curl estimate. For the calculation of the curl amount, at least two variables of the temperature output value of the surface of the transfer material, the humidity output value of the front surface, the temperature output value of the back surface, and the humidity output value of the back surface are used among the output values of the sensor. .

  The functional block 200 of the multifunction machine further includes a curl amount database (hereinafter, the database is simply referred to as DB) 208 in the storage area. The curl amount DB 208 holds a curl calculation table that associates the estimated curl amount with the output value of the sensor for each type identification value of the transfer material information 214 described above.

  In this case, the curl amount calculation unit 202 can refer to the curl calculation table in the curl amount DB 208 and perform a search using the output value of each sensor as a key to obtain a corresponding curl estimation amount. However, although details will be described later, the curl estimation amount can also be calculated using a function expressed by a predetermined expression instead of the curl calculation data of the table structure. In this case, the curl amount DB 208 holds the curl calculation data that holds the coefficient of the functional expression.

  The functional block 200 of the multifunction machine further includes a control value DB 210 that holds a control value calculation table that associates the estimated curl amount with the control value, and the curl correction control value determination unit 204 stores the control value calculation table. Using the curl estimation amount obtained by the curl amount calculation unit 202, a control value for actually performing a desired amount of curl correction in the curl correction device 40 is determined. The control value calculation table defines the control parameters of the curl correction apparatus 40 necessary for performing the curl correction of a desired correction amount.

  The curl correction control value determination unit 204 can search using the estimated curl amount with reference to the control value calculation table in the control value DB 210 to obtain a corresponding control value. As for the control value, the estimated curl amount can be calculated using a predetermined function instead of the control value calculation data having the table structure. The curl correction control unit 206 controls the curl correction device 40 to perform curl correction according to the control value determined by the curl correction control value determination unit 204.

  In the preferred embodiment, the functional block 200 of the multifunction peripheral can further include an update processing unit 218. The update processing unit 218 performs update processing of data in the curl amount DB 208 in order to cope with changes such as the release of new transfer material products distributed in the market and changes in specifications. For example, when the update processing unit 218 detects that the setting of the transfer material information 214 is changed from the input unit 216 and there is no curl calculation data corresponding to the type identification value, the update processing unit 218 regardless of whether the setting is changed or not. The update process is started at the scheduled timing or when the operator gives an instruction.

  In the update process, the update processing unit 218 transmits the model identification value of the multifunction peripheral and the type identification value of the necessary curl calculation data to the transfer material data management unit 260 on the server device 150 side. The transfer material data management unit 260 on the server apparatus 150 side accesses the transfer material DB 262 in which curl calculation data is stored in a database for each type of transfer material distributed in the market, and receives the received model identification value. The curl calculation data corresponding to the type identification value is acquired, and the update data is transmitted to the update processing unit 218 on the multifunction machine side. When the update processing unit 218 acquires update data, the update processing unit 218 updates data in the curl amount DB 208. Since the characteristics of the product itself distributed may change over time, an expiration date is set for the curl calculation data to be updated, and updated to the latest one regularly. It is preferable to be configured.

  Hereinafter, the curl correction control operation executed by the multifunction machine of the present embodiment will be described. FIG. 6 is a flowchart showing the curl correction control operation executed by the multifunction machine of this embodiment. The operation shown in FIG. 6 is started from step S100 in accordance with an appropriate timing when the transfer material passes the sensor or the fixing device. In step S101, the CPU 46 acquires output values from the sensors 41a, 41b, 36, and 39. In step S102, the CPU 46 reads the transfer material information 214, obtains the type identification value designated for the paper feed source cassette of the current process, and sets the obtained output value and the obtained type identification value. The curl estimation amount is obtained using the corresponding curl calculation data.

  In step S103, the CPU 46 determines a control value of the curl correction device 40 according to the calculated curl estimation amount. In step S104, the curl correction device 40 is controlled to change the winding angle in accordance with the determined control value, and the operation is terminated in step S105. After the curl correction control operation is completed, the transfer material is conveyed to the curl correction device 40, curled at a set winding angle, and discharged onto the discharge tray 50.

  FIG. 7 is a flowchart showing an update process executed by the multifunction machine of this embodiment. The update processing shown in FIG. 7 detects that the setting of the transfer material information 214 has been changed, detects that the scheduled timing has arrived regardless of the setting change, or executes update processing from the operator. The instruction is detected and the process starts from step S200. When the update process starts, the update processing unit 218 reads the transfer material information 214 in step S201, and determines in step S202 whether or not an update is necessary. Here, it is determined that updating is necessary when curl calculation data corresponding to the newly set type identification value does not exist in the curl amount DB 208 or when the expiration date has expired. For example.

  If it is determined in step S202 that updating is necessary (YES), the process proceeds to step S203. Subsequently, in step S203, the update processing unit 218 starts communication with the server apparatus 150. In step S204, the update processing unit 218 obtains the type identification value of the transfer material that needs to be updated and the model identification value of the multifunction peripheral. The data is transmitted to the server device, and the corresponding curl calculation data is inquired.

  In step S205, the update processing unit 218 receives update data including the inquiry curl calculation data from the server apparatus, and ends the communication with the server apparatus in step S206. In step S207, the update processing unit 218 updates the data in the curl amount DB 208 according to the received update data, and ends the update process in step S208. On the other hand, if it is determined in step S202 that no update is necessary (NO), the process directly branches to step S208, and the update process is terminated in step S208.

  Hereinafter, the calculation method of the curl estimation amount will be described in more detail with reference to FIGS. 8 and 9. The multifunction machine of this embodiment calculates the curl estimation amount using the humidity output value in the transfer material passage area output from the first sensor 41a and the second sensor 41b.

  FIG. 8B shows that a humidity sensor that detects moisture evaporated from the front and back surfaces of the transfer material is installed immediately after the nip portion 35 of the fixing device, and the humidity in the vicinity of the transfer material is measured. It is a graph which shows the experimental result obtained by measuring the curl amount. In the graph of FIG. 8B, the vertical axis indicates the measured value of the curl amount, and the horizontal axis indicates the difference in humidity output between the front and back humidity sensors. As a result of such an experiment, as shown in FIG. 8B, the curl amount changes approximately in proportion to the difference in humidity output between the front surface and the back surface, and the moisture content (moisture content) originally contained in the transfer material is changed. Accordingly, data whose proportionality constant changes can be obtained. The moisture content can be estimated well from the sum of the humidity outputs of the sensors 41a and 41b. Therefore, in this embodiment, the estimated curl amount is obtained using the sum and difference of the humidity output values of the front and back surfaces of the transfer material.

  FIG. 9 is a diagram illustrating a data structure of curl calculation data. FIG. 9A shows a curl calculation table used in the multifunction machine of this embodiment. In the curl calculation table shown in FIG. 9A, the row represents the range of the difference D of the humidity output, the column represents the range of the sum S of the humidity output, and the cell specified by the row and the column includes the range. The curl estimation amount under the condition corresponding to is held.

  The curl calculation table shown in FIG. 9A is defined for each type identification value. In this embodiment, the curl amount calculation unit 202 stores the curl calculation table corresponding to the type identification value from the curl amount DB 208. , The sum S and the difference D of the humidity output value of the first sensor 41a and the humidity output value of the second sensor 41b are calculated, and the sum S and the difference D are specified in the corresponding range in the read curl calculation table. Read the value from the cell to get the curl estimate.

  The curl calculation table for each type identification value can be generated from experimental data measured for each type of transfer material. For the type identification value corresponding to the classification value and thickness value, for example, the experimental data acquired for each transfer material is grouped by the classification and thickness, and averaged within the group, the classification or A curl calculation table can be generated corresponding to the thickness, and a curl calculation table can be generated using the most common paper in the group as a representative example. The value indicating that the type of transfer material is unknown can be generated, for example, by averaging over all experimental data, and within the group that is considered the most standard. It can be generated by averaging, or a curl calculation table can be generated using the most common paper as a representative example.

  As described above, the curl estimation amount can be calculated using a predetermined function expression such as the following formula (1) without using the curl calculation table having the table structure. In the following formula (1), Y represents the estimated curl amount, and C (S) is a function that defines the relationship between the sum S of humidity output values and the estimated moisture content. The function C (S) is expressed by, for example, a polynomial having the sum S as a variable, and the coefficient can be obtained by curve fitting the above-described experimental data. Further, as shown in FIG. 8B, the curl amount is approximately proportional to the humidity output difference D. Therefore, in the following equation (1), the estimated curl amount Y is expressed by a linear function with respect to the difference D. Has been.

  The coefficient of the function C (S) can be held in the curl amount DB 208 as curl calculation data for each type identification value. The above formula (1) is for illustrative purposes, and is not particularly limited, and more complicated formulas can be used. For example, in another embodiment, a paper thickness value may be included in the equation in addition to the sum S and the difference D of the humidity output values as variables.

  In the above description, the curl estimation amount is calculated using only the humidity output value in the transfer material passage area output from the first sensor 41a and the second sensor 41b. However, in another embodiment, the estimated curl amount can also be calculated using both the humidity output value and the temperature output value in the transfer material passage region output from the first sensor 41a and the second sensor 41b.

  For example, the temperature difference and the humidity difference between the front surface and the back surface show a good correlation, and the curl amount tends to increase as the temperature difference increases. From such knowledge, instead of obtaining the difference between the humidity output values, the temperature difference between the front surface and the back surface is obtained, and the sum of the humidity output values of the sensors 41a and 41b and the difference between the temperature output values are curled. The amount can be estimated. In this case as well, a curl calculation table as shown in FIG. 9A can be used, and a function equation as shown in the above equation (1) can also be used.

  In addition, since the front and back surface temperatures and the surface temperatures of the heat-fixing roller 30 and the pressure roller 37 have good correlations, in another embodiment, the temperature values of the first sensor 41a and the second sensor 41b are used. Instead, temperature output values from the temperature sensor 36 and the temperature sensor 39 that respectively detect the surface temperatures of the heat fixing roller 30 and the pressure roller 37 constituting the nip portion 35 of the fixing device may be used. In this case, the first sensor 41a and the second sensor 41b do not need to have a function of measuring the temperature, and the manufacturing cost of the multifunction machine can be reduced.

  In addition, the amount of curling of transfer materials such as paper varies depending on the fiber thickness, manufacturing process, thickness, etc., but heat-fixing affects the type of transfer material and the amount of shrinkage on the front and back surfaces of the transfer material. There is a knowledge that the curl amount can be estimated with good accuracy by the temperature difference between the surface temperatures of the roller 30 and the pressure roller 37. Therefore, in another embodiment, the estimated curl amount can be obtained from the type of transfer material and the difference between the surface temperatures of the heat fixing roller 30 and the pressure roller 37.

  FIG. 9B shows a curl calculation table used in a multifunction machine according to another embodiment. In the curl calculation table shown in FIG. 9B, the row indicates the range of the temperature output value difference D between the temperature sensor 36 on the heat-fixing roller 30 side and the temperature sensor 39 on the pressure roller 37 side, and the columns are columns. A corresponding curl estimation amount is held in a cell that represents the type of transfer material and is specified by a row and a column. This curl calculation table can be suitably used when the type identification value is a thickness value or a classification value. In this case, the curl amount calculation unit 202 reads the curl calculation table shown in FIG. 9B from the curl amount DB 208, calculates the difference D between the temperature output values of the temperature sensors 36 and 39, and reads the curl calculation data read out. , The curl estimation amount can be acquired by reading the value from the cell specified by the range corresponding to the temperature difference D and the type of the transfer material.

  As described above, the curl generated on the transfer material, such as the humidity and temperature of the front and back surfaces of the transfer material immediately after passing through the fixing device, and the surface temperature of the heat-fixing roller 30 and the pressure roller 37 that apply heat to the transfer material. It is possible to estimate the curl amount with high accuracy by measuring the physical quantity of the factor that directly affects the curl, and estimating the curl amount from the measured value, thereby realizing high-precision curl correction. it can.

  Corresponding to the value indicating that the type of transfer material is unknown, the thickness value specifying the thickness of the transfer material, the classification value indicating the classification of the transfer material, and the value identifying the transfer material of a specific type (brand) With the configuration that provides curl calculation data, it is possible to cope with the details. In other words, when the type of transfer material is unknown, it can be dealt with by using standard or average data. When only the thickness or classification of the transfer material is known, the thickness range or classification Standard or average data can be used, and when a specific type (brand) of the transfer material is known, data specific to the specific type can be used.

  Furthermore, a new product or a product to be distributed is configured by updating the curl calculation data at the timing when a new type identification value that does not hold the curl calculation data is set, the schedule or the instruction. Thus, it is possible to easily cope with changes in characteristics over time, and it is possible to significantly reduce the work burden on the manager at that time.

  Hereinafter, a second embodiment using another curl estimation amount calculation method will be described with reference to FIGS. Since the second embodiment employs the same configuration and operation as the first embodiment, the following description will focus on a curl estimation amount calculation method that is a difference. In the multifunction machine of the second embodiment, the humidity output value in the transfer material passage area output from the first sensor 41a and the second sensor 41b and the surface temperature output values of the heat fixing roller 30 and the pressure roller 37 are obtained. To calculate the curl estimate.

  FIG. 10 is a graph showing the experimental results of measuring the humidity by installing a humidity sensor that detects moisture evaporated from the front and back surfaces of the transfer material immediately after the fixing process, and measuring the distortion amount of the obtained transfer material. is there. The experimental result shown in FIG. 10 can be measured using, for example, the test apparatus 300 shown in FIG.

  In the test apparatus 300 shown in FIG. 12A, first, the paper sample 304 is held in the sample holder 302 and hung vertically downward. Humidity sensors 306 are arranged on both sides of the paper sample 304 so as to be movable up and down with a gap of about 1 mm. A plate 308 heated to a predetermined temperature is attached to both sides of the paper sample 304 so as to be horizontally movable. A heater 310 and rubber 312 are attached to the surface of the plate 308, and a temperature sensor 314 can measure the temperature near the heating surface. The temperature control unit (not shown) can be controlled to a predetermined temperature.

  A weight 316 of about several tens of grams is attached to the lower end of the paper sample 304, and a distance sensor 318 capable of measuring the position of the lower surface of the weight is installed. The distance sensor 318 is preferably a non-contact type using laser light, and preferably has a resolution of 1 μm or less.

  As shown in FIG. 12B, the test machine first pressurizes and heats the paper sample 304 from the left and right with the plate 308 for a predetermined time with a predetermined pressure. Thereafter, after a predetermined time has elapsed, the plate 308 is retracted, and as shown in FIG. 12C, the humidity sensor 306 is lowered along the paper sample 304 to quickly measure the humidity on the paper surface. At the same time, the distance sensor 318 measures the position (height) of the lower end of the weight for about 30 seconds. If the displacement of the weight after a predetermined time is h and the initial length of the paper sample 304 is L, the strain amount X can be calculated by the following equation (2).

  FIG. 10 shows a plot of the amount of distortion against the output value of the humidity sensor by measuring a large number of data using the humidity control of the paper sample and the temperature of the heating plate as the fluctuation factors. By curve fitting the data obtained for each temperature, a function defining the relationship between the output value of the temperature sensor and the amount of distortion can be obtained.

  In the second embodiment, the curl amount calculation unit 202 outputs the humidity output value in the transfer material passage region output from the first sensor 41a and the second sensor 41b, and the transfer material of the heat fixing roller 30 and the pressure roller 37. Using the surface temperature output value in the vicinity of the passage time, it is input to a function that defines the relationship between the output value of the temperature sensor and the distortion amount. First, the front surface distortion amount E1 and the back surface distortion amount E2 are transferred. Is calculated. Then, an estimated curl amount (curl curvature) R is calculated by the following equation (3) using the thickness t of the transfer material to be used. The thickness t of the transfer material may be a thickness value input as a type identification value, may be included as a coefficient in the curl calculation data of each type identification value, or the type of transfer material is unknown. In some cases, standard values may be used.

  Further, as described above, the curl estimation amount can be calculated using a curl calculation table having a table structure without using the function shown in the above formula. FIG. 11 is a diagram illustrating a data structure of curl calculation data that can be used in the second embodiment. The curl calculation table shown in FIG. 11A is defined for each range and thickness of the humidity output value, the row indicates the temperature output range of the temperature sensor 39 on the pressure roller 37 side, and the column indicates the heat fixing roller 30. The range of the temperature output of the temperature sensor 36 on the side is indicated, and the corresponding curl estimation amount is held in the cell specified by the row and the column. Note that the curl amount can be satisfactorily determined if there are at least three variables of the humidity output on either side and the temperature output value related to the temperature in the vicinity of both sides. Therefore, the humidity output value used here is the first Any one of the sensor 41a and the second sensor 41b may be used, or an average value of the humidity output values of the first sensor 41a and the second sensor 41b may be used. Note that the curl calculation data shown in FIG. 11A is created from experimental data obtained using the test apparatus shown in FIG.

  In the case of using the curl calculation table shown in FIG. 11A, the curl amount calculation unit 202 has a thickness obtained from the curl amount DB 208 within the range in which the humidity output values obtained from the sensors 41a and 41b fall within the applicable range and the type identification value. The curl calculation data corresponding to the range corresponding to is read. Then, the curl amount calculation unit 202 reads the value from the cell specified in the range in which the temperature output value of the temperature sensor 39 on the pressure roller 37 side and the temperature output value of the temperature sensor 36 on the heating and fixing roller 30 side correspond, Get curl estimator.

  FIG. 11B is a diagram illustrating another data structure of curl calculation data that can be used in the second embodiment. Note that the curl calculation data shown in FIG. 11B is preferably used when the type identification value designates a specific type of transfer material including the difference in supply source. In the curl calculation table shown in FIG. 11B, the row indicates the temperature output range of the temperature sensor 39 on the pressure roller 37 side, and the column indicates the temperature on the heat fixing roller 30 side, as in FIG. 11A. The range of the temperature output of the sensor 36 is represented, and a corresponding curl estimation amount is held in a cell specified by a row and a column. Unlike the case of FIG. 11A, the curl calculation table shown in FIG. 11B is defined for each range of humidity output values and type identification values.

  When the curl calculation table shown in FIG. 11B is used, the curl amount calculation unit 202 is in the range corresponding to the humidity output values obtained from the sensors 41a and 41b from the curl amount DB 208, and the type identification value is The curl calculation data corresponding to the corresponding range is read. Then, the curl amount calculation unit 202 reads the value from the cell specified in the range in which the temperature output value of the temperature sensor 39 on the pressure roller 37 side and the temperature output value of the temperature sensor 36 on the heating and fixing roller 30 side correspond, Get curl estimator.

  Since the curl calculation table shown in FIG. 11B can be defined for each type of transfer material including differences in supply sources, curl correction can be performed with higher accuracy. In the second embodiment, the surface temperature of the heat fixing roller 30 and the pressure roller 37 is measured as a factor related to the front and back temperature of the transfer material. However, in other embodiments, the sensor 41a is used. , 41b may be used for temperature measurement.

  Hereinafter, a third embodiment having another configuration will be described with reference to FIGS. In addition, since 3rd Embodiment has a structure similar to 1st Embodiment, it demonstrates below centering on difference. Further, the same components as those in the first embodiment will be described using the same reference numerals.

  FIG. 13 shows a schematic configuration of a multifunction machine according to the third embodiment. A multi-function device 400 shown in FIG. 13 generally has the same configuration as that of the first embodiment shown in FIG. 1, but the multi-function device 1 shown in FIG. Instead of the first sensor 41a and the second sensor 41b that are provided, a humidity sensor 402 provided on the upstream side of the transfer material conveyance path is provided. In the example shown in FIG. 13, the humidity sensor 402 is installed on the downstream side of the transport roller 12 and on the upstream side of the transfer roller 23. This is because it is possible to detect the humidity of the transfer material after printing the surface at the time of double-sided printing at this position.

  Further, even while the transfer material is loaded on the cassette 51 or the cassette 52, the transfer material may absorb moisture depending on the installation environment of the multi-function device 400, and the moisture content may change. In the state where the transfer material is laminated, the moisture content increases from the end portion of the transfer material. Therefore, even when the moisture content at the central portion is low, the moisture content at the end portion may be high. Therefore, the multi-function device 400 of this embodiment includes a plurality of humidity sensors 402 in the width direction of the transfer material, and more preferably includes at least one humidity sensor on the end side of the transfer material. As a result, it is possible to avoid overlooking the high moisture content generated at the end portion and to correct the curl appropriately.

  As the humidity sensor 402, similarly to the sensors 41a and 41b in the first embodiment, a capacitance type humidity sensor or an electric resistance type humidity sensor can be used. Further, the response of the humidity sensor 402 at that time can be 1 second or less, preferably 0.1 second or less. Since there is a correlation between the moisture content of the transfer material and the humidity in the vicinity of the transfer material, the humidity in the vicinity of the surface of the transfer material is measured using a humidity sensor on the upstream side of the fixing device in the transfer material conveyance path in this way. As a result, it can be suitably used for calculating the estimated curl value as a value that approximates the overall moisture content of the transfer material.

  Further, the multifunction machine 400 shown in FIG. 13 is provided with a thickness detection sensor 406 for detecting the thickness of the transfer material on the upstream side of the conveying roller 12 so that the thickness of the transfer material can be measured by the apparatus itself. Yes.

  FIG. 14 is a diagram illustrating a configuration of a thickness detection sensor that can be suitably used in the present embodiment. The thickness detection sensor 406 includes a thickness detection roller 420, a thickness detection lever 422, and a drive roller 426. The thickness detection roller 420 is attached to the thickness detection lever 422 and pressed against the driving roller 426 by a spring 424. The thickness detection lever 422 is supported so as to be rotatable about a fulcrum 428. The driving roller 426 is rotated in the direction of the arrow in the drawing by a driving means (not shown), and conveys the transfer paper. The displacement sensor 430 measures the rotational displacement of the thickness detection lever 422. The driving roller 426 is preferably a rubber roller in order to secure a frictional driving force for transporting the transfer material, and a hardness of 50 degrees (Asker A type) or more is desirable in order to increase the thickness detection accuracy.

  When a transfer material enters between the driving roller 426 and the thickness detection roller 420, the thickness detection roller 420 is pushed up, and the thickness detection lever 422 rotates. Then, the distance from the displacement sensor 430 changes, an output corresponding to the distance is generated, and an output value corresponding to the thickness of the transfer material is output. In this way, when the thickness detection sensor 406 is used, the apparatus itself measures the thickness of the transfer material, so that the operator's trouble of inputting the paper thickness value for each cassette is saved. , Workability is improved. Furthermore, it is possible to prevent correction errors due to input errors.

  Note that the thickness detection sensor 406 has an arbitrary configuration, and as described in the first embodiment, information such as the paper type and thickness input from an operator or input from an external personal computer device is used. May be used.

  If the thickness of the transfer material is greater than a certain value, the amount of heat required to melt and fix the toner on the transfer material increases, so the nip time of the fixing device needs to be increased. Accordingly, the transfer speed of the transfer material can be changed in accordance with the output value of the thickness detection sensor 406 corresponding to the increase in the nip time. Further, since the curl amount also changes depending on the nip time, the information on the conveyance speed is used in the calculation of the curl estimation amount according to this embodiment.

  Further, in the case of coated paper or the like in which the air permeability of the transfer material is significantly different from that of normal paper, the curl amount may be different even under the same thickness, the same moisture content, and the same heating conditions. Therefore, for such a transfer material, it is preferable to input a paper type from the input unit of the multi-function device 400 or a connected computer device, and to calculate an estimated curl amount using information on the paper type. In addition, the multifunction machine 400 shown in FIG. 13 is provided with a transfer material position detection sensor 404, which will be described in detail later, in order to grasp the position of the transfer paper to be conveyed.

  FIG. 15 illustrates functional blocks of the multifunction machine according to the third embodiment. The functional block 500 of the MFP 400 shown in FIG. 15 includes a curl amount calculation unit 202, a curl correction control value determination unit 204, a curl correction control unit 206, an input unit 216, as in the first embodiment. A curl amount DB 208 and a control value DB 210 are included. The input unit 216 receives designation of the type of transfer material currently set in the paper feed cassettes 51 and 52 from the operator, and holds it in an appropriate storage area such as the RAM 116 or the NV-RAM 118 as transfer material information. The input unit 216 receives designation of a transfer material type from an external computer device or the like via a network, and holds it as transfer material information.

  The curl amount calculation unit 202 is connected to the heat fixing roller temperature sensor 36, the pressure roller side temperature sensor 39, the input unit 216, and the curl amount DB 208. In this embodiment, the humidity sensor 402, the thickness detection sensor 406, and the conveyance are further provided. It is connected to the speed determination unit 410. The conveyance speed determination unit 410 controls the conveyance speed according to the thickness of the transfer material. The curl amount calculation unit 202 obtains output values from the various sensors described above, reads transfer material information as appropriate, refers to the curl calculation table of the curl amount DB 208, searches using each output value as a key, and Find the curl estimate.

  The functional block 500 of the multifunction machine further includes a timing determination unit 412. A transfer material position detection sensor 404 and a conveyance speed determination unit 410 are connected to the timing determination unit 412. As described above, when the thickness is equal to or greater than the predetermined value, it is necessary to increase the nip time. However, for example, when the thickness of the transfer material is equal to or greater than a predetermined value, the conveyance speed determination unit 410 sets the conveyance speed to the normal speed. Decide in half. In this case, the speed of the motor that drives each roller of the transfer material conveyance path is halved, and control according to the conveyance speed is performed in other processes. The conveyance speed determination unit 410 can be realized by arithmetic processing of the CPU 46 of the multifunction machine 400.

  The timing determination unit 412 calculates the timing at which the transfer material reaches the curl correction device 40 according to the timing at which the transfer material position detection sensor 404 detects the sheet passing and the transport speed determined by the transport speed determination unit 410. The curl correction control value determination unit 204 determines a control value in the curl correction device 40 from the estimated curl amount obtained by the curl amount calculation unit 202 using the control value calculation table in the control value DB 210.

  The curl correction control unit 206 is connected to the curl correction device 40 and the timing determination unit 412, receives information on the timing at which the transfer material reaches the curl correction device 40 from the timing determination unit 412, and the curl correction control value determination unit 204 According to the determined control value, correction control of the curl correction device 40 is started at an appropriate timing. In the preferred embodiment, the functional block 500 of the multifunction peripheral can further include the update processing unit 218 described in the first embodiment, but the description of the update processing is omitted.

  The curl correction control operation executed by the multifunction machine according to the third embodiment will be described below. FIG. 16 is a flowchart showing the curl correction control operation executed by the multifunction machine of this embodiment. The operation shown in FIG. 16 is started from step S300 in accordance with an appropriate timing when the transfer material reaches the thickness detection sensor 406. In step S301, the CPU 46 causes the thickness detection sensor 406 to measure the thickness of the transfer material conveyed from the cassettes 51, 52, and acquires the measured value. In step S302, the CPU 46 detects the position of the transfer material by the transfer material position detection sensor 404, causes the humidity sensor 402 to measure the humidity near the transfer material surface at an appropriate timing, and acquires the measured value.

  In step S <b> 303, the CPU 46 determines the timing from the temperature sensor 36 of the heat fixing roller 30 and the temperature sensor 39 of the pressure roller 37 immediately before the transfer material onto which the toner image has been transferred by the transfer roller 23 arrives at the fixing device. Get a measurement of the surface temperature. In step S304, the CPU 46 further acquires a conveyance speed from the conveyance speed determination unit 410, and acquires transfer material information from the input unit 216 in step S305. In step S306, the CPU 46 refers to the curl calculation table in the curl amount DB 208 and calculates the curl estimation amount.

  In step S307, the CPU 46 determines the control value of the curl correction apparatus 40 by referring to the control value calculation table in the control value DB 210 according to the determined curl estimation amount. In step S308, the CPU 46 calculates the timing at which the transfer material reaches the curl correction device 40 using the timing at which the transfer material position detection sensor 404 detects the sheet passing and the determined conveyance speed. Correction control of the curl correction device 40 is started so as to change the winding angle at an appropriate timing according to the control value, and this operation is finished in step S309. After the curl correction control operation is completed, the transfer material is conveyed to the curl correction device 40, curled at a set winding angle, and discharged onto the discharge tray 50. This timing determination makes it possible to correct the curl appropriately for each sheet in accordance with the characteristics of the transfer material and the temperature changes of the heat fixing roller 30 and the pressure roller 37 of the fixing device.

  Hereinafter, the curl estimation amount calculation method according to the third embodiment will be described in more detail with reference to FIG. In the multifunction machine of this embodiment, the estimated curl amount is calculated using the humidity output value in the transfer material passage region output from the humidity sensor 402 and the surface temperature output values of the heat fixing roller 30 and the pressure roller 37. To do.

  As described with reference to FIG. 8B, as the water content increases, the curl amount increases, and the temperature difference between the surface temperatures of the heat fixing roller and the pressure roller that affects the humidity on the front and back surfaces respectively. If it increases, the curl amount increases. When the moisture content is used as a value used in the curl calculation table, a correlation coefficient between the output value of the humidity sensor 402 and the moisture content of the transfer material is calculated, and the output value of the humidity sensor 402 is calculated when calculating the estimated curl amount. Is converted into a moisture content to correspond to the value in the curl calculation table. Further, when creating the curl calculation table data, a sensor equivalent to the humidity sensor 402 may be used so that the curl amount is associated with the humidity value near the surface of the transfer material. In this case, the humidity sensor 402 Can be used as a database.

  FIG. 17 shows a data structure of a curl calculation table that can be suitably used in the multifunction machine of the third embodiment. In the curl calculation table shown in FIG. 17, the row indicates the range of the temperature output value difference D between the temperature sensor 36 on the heat fixing roller 30 side and the temperature sensor 39 on the pressure roller 37 side, and the column indicates the humidity sensor 402. Represents the range of the moisture content σ converted from the output of, and the cell specified by the row and the column holds the curl estimation amount under the condition corresponding to the range.

  Since the curve shown in FIG. 8B changes depending on the paper thickness, heating time, and paper type, measurement is performed under each condition, a database is created, and curl calculation data as shown in FIG. 17 is created in advance for each condition. It is preferable. Since it is not efficient to cover all conditions, using the data measured for typical transfer material thickness and heating time, for the transfer material thickness value and heating time value in between, The value of the cell can be calculated by linear interpolation. Further, with respect to a change in the curl amount depending on the paper type, a characteristic coated paper can be used to obtain a change due to the air permeability, and a coefficient thereof can be obtained. Then, the curl calculation data can be converted by multiplying the coefficient according to the air permeability to calculate the curl estimation amount.

  As an example, the curl estimation amount Y is calculated using the following equation (4) using the curl A of the curl calculation table, the air permeability ap of the coated paper, and the coefficient E corresponding to the air permeability. be able to.

  The coefficient ap can be obtained by curve fitting the data obtained by the above-described experiment. In addition, the said Formula (4) aims at an illustration, Comprising: It does not specifically limit.

  As described above, according to the above-described embodiment, it is appropriate to cope with fluctuations in factors affecting the fixing state such as the temperature state in the fixing device and the paper characteristics accompanying the change in the operation state of the image forming apparatus. It is possible to provide an image forming apparatus and a curl correction method capable of realizing precise and precise curl correction. Further, according to the above-described embodiment, even when the paper type cannot be specified or the paper characteristics fluctuate, the image forming apparatus and the curl correction method capable of realizing the curl correction with sufficient accuracy. Can be provided. In addition, it is possible to provide an image forming apparatus and a curl correction method capable of realizing curl correction with higher accuracy when the type of paper can be specified.

  In the above-described embodiment, a multifunction peripheral is used as an example of an image forming apparatus. However, a transfer material in which a toner image is carried on a pressure contact portion of a pressure contact member such as a copying machine, a printer, or a facsimile machine is used. It can be configured as any image forming apparatus including a fixing device that passes and fuses the toner image by heat and fixes the toner image on the transfer material, and a curl correction device that corrects deformation of the transfer material such as curl.

  The above functions can be realized by computer-executable programs written in legacy programming languages such as assembler, C, C ++, C #, Java (registered trademark), object-oriented programming languages, etc. ROM, EEPROM, EPROM, Store in a device-readable recording medium such as flash memory, flexible disk, CD-ROM, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, Blu-ray disc, SD card, MO, or distribute it through an electric communication line can do.

DESCRIPTION OF SYMBOLS 1 ... MFP, 2 ... Intermediate transfer belt, 3 ... Photosensitive drum, 4 ... Charging roller, 5 ... Polygon mirror, 6 ... Light irradiation device, 7 ... Developing device, 9 ... Roller, 12 ... Conveying roller, 14 , 21, 22 ... Roller, 23 ... Transfer roller, 25 ... Power source, 30 ... Heat fixing roller, 30a ... Pipe-shaped metal core, 30b ... Resin layer, 31 ... Power source, 33 ... Inlet guide, 34 ... Heater, 35 ... Nip 36, temperature sensor, 37 ... pressure roller, 39 ... temperature sensor, 40 ... curl correction device, 41a ... first sensor, 41b ... second sensor, 42 ... transport drive roller, 43 ... spring, 44 ... cam, 45 ... Endless belt, 46 ... CPU, 47 ... Control device, 50 ... Paper discharge tray, 51 ... Paper feed cassette, 52 ... Paper feed cassette, 100 ... Hardware configuration, 110 ... Multifunction machine, 112 ... CPU, 114 ... RO 116 ... RAM, 118 ... NV-RAM, 120 ... display device, 122 ... input device, 124 ... printer, 126 ... scanner, 128 ... NIC, 130 ... network, 150 ... server device, 152 ... CPU, 154 ... ROM, 156 ... RAM, 158 ... display device, 160 ... input device, 162 ... NIC, 164 ... HDD, 200 ... functional block, 202 ... curl amount calculation unit, 204 ... curl correction control value determination unit, 206 ... curl correction control unit, 208 ... curl amount DB, 210 ... control value DB, 214 ... transfer material information, 216 ... input unit, 218 ... update processing unit, 250 ... functional block, 260 ... transfer material data management unit, 262 ... transfer material DB, 300 ... Test device 302 ... Sample holder 304 ... Paper sample 306 ... Humidity sensor 308 ... Plate 310 ... Heat 312 ... Rubber 314 ... Temperature sensor 316 ... Weight 318 ... Distance sensor 400 ... Multifunction machine 402 ... Humidity sensor 404 ... Transfer material position detection sensor 406 ... Thickness detection sensor 410 ... Conveying speed determination unit DESCRIPTION OF SYMBOLS 412 ... Timing determination part 420 ... Thickness detection roller 422 ... Thickness detection lever 424 ... Spring 426 ... Drive roller 428 ... Supporting point 430 ... Displacement sensor 500 ... Functional block P ... Transfer material

Japanese Patent Laid-Open No. 2002-316761 Japanese Patent No. 4009051 JP 2007-328054 A JP 2006-208509 A

Claims (9)

A fixing device that passes the transfer material through the heated pressure contact portion and fixes the toner image carried on the transfer material; and a curl correction device that corrects curl generated in the transfer material that has passed through the fixing device. An image forming apparatus comprising:
It is provided in the transfer material conveyance path in the image forming apparatus, is disposed in the vicinity of the pressure contact portion of the fixing device, and is near the first surface of the transfer material that has passed through the pressure contact portion of the fixing device. A first detection sensor means comprising a humidity sensor for detecting humidity ;
A second detection sensor means arranged to face the first detection sensor means, and comprising a humidity sensor for detecting the humidity in the vicinity of the second surface of the transfer material that has passed through the pressure contact portion of the fixing device ;
Curl estimation using the sum and difference of the output value of the humidity on the first surface side output from the first detection sensor means and the output value of the humidity on the second surface side output from the second detection sensor means Computing means for computing the quantity;
An image forming apparatus comprising: a control unit configured to control the curl correction apparatus by setting a control value corresponding to the calculated estimated curl amount.   2. The image according to claim 1, wherein the calculation unit reads transfer material information that characterizes a shrinkage characteristic of the transfer material in use that is input to the image forming apparatus, and obtains the estimated curl amount according to the transfer material information. Forming equipment. Said calculating means, the curl from the output value of the humidity of the said second surface side to the output value of the humidity of the first the first surface side outputted from the sensor means and the output from the second sensor means A function for calculating an estimated amount, or an output value of humidity on the first surface side output from the first detection sensor means, and an output value of humidity on the second surface side output from the second detection sensor means The image forming apparatus according to claim 1, wherein the curl estimation amount is obtained using a table associated with the curl estimation amount.   The image forming apparatus according to claim 1, further comprising an updating unit that communicates with a server device connected via a network and performs an updating process of a coefficient of a function or a table for obtaining the estimated curl amount. The image forming apparatus according to claim 1. A fixing device that passes the transfer material through the heated pressure contact portion and fixes the toner image carried on the transfer material; and a curl correction device that corrects curl generated in the transfer material that has passed through the fixing device. An image forming apparatus comprising:
A first detection sensor means provided in a transfer path of the transfer material in the image forming apparatus and detecting and outputting a humidity in the vicinity of at least one surface of the transferred transfer material;
Second detection sensor means for detecting and outputting at least one physical quantity related to one or both of temperature and humidity in the vicinity of at least one surface of the transfer material that has passed through the pressure contact portion of the fixing device;
Arithmetic means for calculating an estimated curl amount from an output value of humidity output from the first detection sensor means and an output value of at least one physical quantity output from the second detection sensor means;
Control means for controlling the curl correction device by setting a control value corresponding to the calculated curl estimation amount;
Wherein the first sensor means, the proximity to the contact portion are arranged, the first surface vicinity and the second surface of the transfer material has passed through the pressure contact portion of each of the fixing device of the fixing device At least one humidity sensor for detecting one or both of the neighboring humidity, wherein the second detection sensor means respectively determines the surface temperatures of both the pressure member and the fixing heating member constituting the pressure contact portion. Including two temperature sensors that detect physical quantities, and the computing means defines a correlation between the estimated curl amount of the transfer material for at least three variables including two surface temperatures and at least one humidity defined for each type of transfer material An image forming apparatus that obtains the estimated curl amount corresponding to the type of the transfer material using a function or a table. Comprising a thickness detection sensor that detects the thickness of the transfer material conveyed, an image forming apparatus according to any one of claims 1-5. The image forming apparatus according to claim 6 , wherein a transfer material conveyance speed is determined according to a thickness output from the thickness detection sensor, and the calculation unit obtains the estimated curl amount according to the conveyance speed. The calculating means calculates the curl estimated amount for each transfer material conveyed, an image forming apparatus according to any one of claims 1-7.   The transfer material information characterizing the shrinkage characteristics of the transfer material includes a value indicating the thickness of the transfer material, a value identifying the classification of the transfer material, or a value identifying a unique type of the transfer material. The image forming apparatus described in 1.