JP6038756B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus and a method for suppressing curling (warping) occurring in a sheet when an image is formed, recorded, and discharged.

  Some image forming apparatuses such as copiers, facsimiles, and multifunction peripherals cause the paper to curl before the image is formed and recorded on the paper and discharged. If the paper is strongly curled, the paper may be bent or soiled, the image formation accuracy may be degraded (defective size or shape, or color quality may be degraded), or a paper jam may occur in the paper transport path in the image forming apparatus. Such a conveyance failure may be caused. Furthermore, it may lead to failure or unexpected accidents.

In general, in an image forming apparatus that uses heat for image recording, paper curl is likely to occur, and in particular, the image is fixed to the paper by heat (the toner attached to the paper is fixed by heating and pressing). In the image forming apparatus, the curl of the paper tends to become remarkable.
In order to eliminate the trouble caused by the curling of the paper, there is an image forming apparatus having a mechanism for suppressing curling, such as a decurler (decurling mechanism).

JP 2004-175567 A JP 2012-098477 A JP 2002-348023 A

Japanese Patent Application Laid-Open No. 2004-175567 exemplifies a configuration in which the temperature of a sheet or the temperature of a conveying roller is measured and the sheet after fixing is cooled according to the temperature. This suppresses curling.
Japanese Patent Laid-Open No. 2012-098477 discloses an image forming apparatus for forming and recording images on both sides of a sheet, and a cooling conveyance path between a recording and fixing unit on the first surface and a recording and fixing unit on the second surface. A configuration in which the paper is cooled by measuring the temperature is illustrated. This improves the double-sided image formation accuracy.
However, in these examples, since the curling of the paper is corrected, a dedicated conveyance path is essential. For this reason, the machine configuration is increased and complicated, which increases the production cost and the maintenance cost.

On the other hand, Japanese Patent Application Laid-Open No. 2002-348023 has a measurement unit for measuring a curl shape, uses a blank sheet or a sheet on which a reference image is formed as a reference sheet, stores the curl amount of the reference sheet, A configuration in which the difference between the image area ratio and the reference value is calculated as a correction value and the curl is corrected is illustrated.
However, in this example, although the curl correction amount is calculated based on the temperature change during paper conveyance and the paper temperature after ejection, and the curl correction is performed, the curl is corrected based on the stored reference value. If an element that affects the curl amount changes, the curl correction cannot be controlled and there is a possibility that the curl is reversed.

  The present invention has been made in view of such points, and an object of the present invention is to perform optimal control on curl generated on a sheet, and to perform decurl optimal for reverse curl when reverse curl occurs. An object of the present invention is to provide an image forming apparatus that performs control or fixing temperature control.

The image forming apparatus of the present invention forms an image on a recording medium, and includes deformations that may occur on the recording medium during the forming process, including partial heat treatment or pressure treatment, or both heating and pressure treatment. An image forming apparatus that corrects by a correction process and corrects and discharges by a correction unit that can change the correction amount, and detects heat at a plurality of predetermined portions of the recording medium immediately after being discharged and parts, wherein it comprises a calculating unit for calculating the temperature distribution information group in a predetermined surface of the recording medium based on a predetermined temperature of the plurality of sites, and a storage unit for storing reference temperature distribution information group is the discharge The calculation unit calculates a temperature distribution information group of temperatures detected by the heat detection unit in a state in which the deformation that has occurred in the recording medium is corrected to an appropriate state by the correction unit, and serves as the reference temperature distribution information group A temperature distribution information group of temperatures detected by the heat detection unit is calculated by the calculation unit every time the recording medium stored in the storage unit and the image is formed and corrected is discharged, and the measured temperature distribution information group Compared with the reference temperature distribution information group, the correction amount by the correction unit is changed so as to approximate the arrangement state of the measured temperature distribution information group to the arrangement state of the reference temperature distribution information group .
Further, the image forming apparatus of the present invention forms an image on a recording medium, and deforms the recording medium during the image forming process by partially heating or pressing, or both heating and pressing. An image forming apparatus that performs correction processing including correction processing and performs correction processing by a correction unit that can vary the correction amount and discharges the image forming apparatus, and can detect temperatures of a plurality of predetermined portions of the recording medium immediately after being discharged A heat detection unit; a calculation unit that calculates a temperature distribution information group on a predetermined surface of the recording medium based on temperatures of the predetermined plurality of parts; and a storage unit that stores a reference temperature distribution information group, The reference temperature distribution information is calculated by calculating the temperature distribution information group of the temperatures detected by the heat detection unit in a state in which the deformation that has occurred in the discharged recording medium is corrected to an appropriate state by the correction unit. group And then stored in the storage unit, before Symbol reference temperature distribution information group arrangement state and the arrangement of the measured temperature distribution information group the temperature distribution information group is calculated is the arithmetic unit of the temperature detected by the heat detecting section The arrangement state of the measured temperature distribution information group is approximated to the arrangement state of the reference temperature distribution information group each time the recording medium on which the image is formed and corrected is discharged until the difference approaches a predetermined range. The process of changing the correction amount by the correction unit is repeated.

  As a result, according to the present invention, it is possible to suppress the curling of the paper without newly providing a decurling dedicated conveying path or the like that has a complicated mechanical configuration and increases production cost and maintenance cost, and further, occurrence of reverse curling. As a result, it is possible to control the curl correction so as to suppress the phenomenon.

1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a main part of an image forming apparatus according to an embodiment of the present invention. In embodiment of this invention, it is a figure which shows a mode that the paper P is discharged | emitted from the discharge part 46a over time. In an embodiment of the present invention, it is a figure at the time of seeing paper P from one side. It is a figure which shows an example of the temperature transition measured along each transition state in FIG. 3 of this Embodiment. In the embodiment of the present invention, it is a diagram showing the state in which curled paper P is discharged from the discharge unit 46a over time. It is a figure which shows an example of the temperature transition measured along each transition state in FIG. 6 of this Embodiment. In the embodiment of the present invention, it is a diagram showing the state in which reversely curled paper P is discharged from the discharge unit 46a over time. It is a figure which shows an example of the temperature transition measured along each transition state in FIG. 8 of this Embodiment. It is a flowchart which shows an example of the flow of the process sequence in this Embodiment. It is a schematic diagram which shows the internal structure which concerns on the modification of the principal part of this Embodiment.

Next, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a diagram showing an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus of the present embodiment is a copying machine 1 using an electrophotographic (dry electrophotographic) system, and uses a main body unit 4 for performing various processes such as image formation on a document reading unit 2 and image formation. It comprises an operation unit 51 and the like for a person to perform various operations.

  The document reading unit 2 to be read is disposed above the main body unit 4, but has a general configuration and is not a characteristic part of the present invention, and thus detailed illustration and description are omitted. A paper discharge space 6 is formed between the document reading unit 2 and the main body unit 4, and a thermopile 45 (temperature sensor) as an example of a heat detection unit is provided in a part thereof. Since this thermopile 45 is also an element having a general configuration, detailed illustration of the inside is omitted.

FIG. 2 is a diagram showing the main part and the main body 4 of the image forming apparatus according to the embodiment of the present invention.
The image forming unit 41 serving as a transfer unit transfers toner (not shown) to a sheet P as an example of a recording medium pulled out from the sheet tray 40. The sheet P on which an image is formed by toner transfer is conveyed to a fixing unit 42 as an example of a fixing unit, and is pressed and heated by a heat roller 42a and a press roller 42b as an example of a first roller. Thus, the image is fixed on the paper P. In addition, a photo interrupter 43 that is a position sensor for detecting the movement of the paper P (detecting the edge of the paper by shading) is provided in the conveyance path in the vicinity of the fixing unit 42.

  The paper P on which the image has been formed and fixed is discharged from the discharge portion 46a or the double-sided print discharge portion 46b to the discharge space 6. In the present embodiment, an example of the correction portion is provided on the conveyance path to the discharge portion 46a. A curl correction unit 44 is provided. The curl correction unit 44 restores the curled paper P to its original uncurled state by applying a strong pressure, pulling force (or friction) or heat to a predetermined surface of the paper P with a roller or the like. . The curl correction unit 44 can adjust the force, heat, and the like that determine the amount of curl correction in response to an instruction from a control unit, which will be described later.

The paper P discharged into the paper discharge space 6 (after processing for both sides in the case of double-sided printing) is accumulated in the discharge tray 49 on the upper surface of the main body unit 4. The thermopile 45 is attached to a position that is not covered by the discharged and accumulated paper P (the left end side in FIG. 2).
In general, a thermopile is a thermocouple assembly (thermocouple array) that outputs a temperature (voltage) signal proportional to a local temperature difference or temperature gradient from incident infrared rays or the like. . That is, it is an element that has a certain degree of directivity and detects temperature by a point, line, or surface. In the example shown in FIG. 2, the thermopile 45 is attached so as to detect the temperature in the direction of the one-dot chain line arrow.

The copying machine 1 as shown in FIGS. 1 and 2 has a control unit 5 as an example of a control unit in the document reading unit 2 or the main body unit 4. The control unit 5 includes an operation unit 51, a storage unit 52 as an example of a storage unit, a calculation unit 53 as an example of a calculation unit, and an interface unit (not shown).
The operation unit 51 displays various types of information to the user of the present embodiment and receives operation signals and information from the user.

  The storage unit 52 temporarily stores image data read by the document reading unit 2 and stores curl information calculated every time the paper P is discharged into the paper discharge space 6 temporarily or for a long time. . As the storage unit 52, a magnetic disk (hard disk), a semiconductor memory (RAM = random access memory, flash memory), or the like is used in accordance with a holding period required for storing various types of information and a required read / write speed. An area for storing reference temperature transition data (reference temperature distribution information group) to be described later may be supported by a read-only memory (ROM, mask ROM, one-time PROM, etc.).

Based on the paper detection signal sent from the photo interrupter 43, the temperature signal sent from the thermopile 45, and the like, the calculation unit 53 has a temperature distribution (temperature transition data, temperature distribution information group) corresponding to the curled state of the discharged paper P. Is calculated.
Control of the heating amount (heat generation amount) and pressurization amount in the fixing unit 42, conveyance control of the paper P based on a paper detection signal sent from the photo interrupter 43, etc., control of the curl correction amount in the curl correction unit 44, etc. Is done through the department.

In the present embodiment, the temperature distribution (temperature transition) of the paper P discharged into the paper discharge space 6 is measured by the thermopile 45. The first measuring method will be described below.
FIG. 3A to FIG. 3F are diagrams illustrating the state in which the paper P is discharged from a discharge unit 46a as an example of a correction discharge unit over time. In addition, in each part shown in FIG. 3, the same code | symbol is attached | subjected to the site | part corresponded to each part shown in the above-mentioned FIG. 1 and FIG. 2, and the detailed description is abbreviate | omitted (this shall apply hereafter).

FIG. 3 shows a case where the paper P is substantially properly curled. That is, in the example shown in FIG. 3, as the paper P changes from (a) to (b) to (c) to (d), the end portion (the left end portion in this example) hangs slightly due to its own weight. .
Further, the paper P is discharged. In (e), the end of the paper P comes into contact with the discharge tray 49, and in (f), the substantially central portion of the paper P is slightly hung down by its own weight.

FIG. 4 is a schematic plan view when the paper P is viewed from one side, and the rough part where the temperature is measured by the thermopile 45 is indicated by broken-line circles. In addition, the code | symbol of (a)-(f) shown in this FIG. 4 respond | corresponds with each of (a)-(f) in FIG.
That is, in the state shown in FIG. 3 (a), the temperature of the dotted circle indicated by (a) in FIG. 4 is measured, and in the state shown in FIG. 3 (b), in FIG. 4 (b). The temperature of the dotted circle shown is measured.

FIG. 5 is a graph showing an example of temperature transition measured along each transition state in FIG. 3 and FIG. The reference numerals (a) to (f) shown in FIG. 5 also correspond to (a) to (f) in FIG. 2 or FIG. In the graph shown in FIG. 5, y is temperature.
X in the graph shown in FIG. 5 is time, and the time when the photo interrupter 43 shown in FIGS. That is, x in the graph shown in FIG. 5 is proportional to the position from the edge of the paper P (the length in the transport direction).

  As described above, in the example shown in FIG. 3, the paper P is properly curled and discharged into the paper discharge space 6, and an example of the temperature transition from the end of the paper P corresponding to this is shown in FIG. 5. Suppose that it was as the graph. However, the graph shape (trend) of the temperature transition differs depending on the paper quality (composition, density, fiber direction) of the paper P, and the density and density of the image to be formed (image forming ratio per unit area of the paper).

  Therefore, temperature transition (temperature distribution) data when the paper P is properly curled is stored in the storage unit 52 in advance. Alternatively, all or part of the image data in this case (a predetermined number of extracted data sufficient to determine the tendency of the image) is stored in the storage unit 52 in combination with the temperature transition.

On the other hand, FIGS. 6 (a) to 6 (f) are diagrams showing the state in which the sheet P is discharged from the discharge unit 46a over time, but the degree of curl correction for the sheet P is smaller than that in FIG. This is an example of the case where the curl remains.
In the example shown in FIG. 6, since the paper P is curled, the end portion (left end portion in this example) has already drooped drastically during the transition from FIG. 6A to FIG. 6B. Further, at the time of transition to FIG. 6C, the end of the paper P comes into contact with the discharge tray 49, and the middle of the paper P hangs down by its own weight in (d) to (e) to (f). The curl has become smaller.

  FIG. 7 is a graph showing an example of the temperature transition measured along each transition state in FIG. 6, as in the combination of FIG. 3, FIG. 4, and FIG. In FIG. 7, an example of the graph when the paper P shown in FIG. 5 is properly curled and discharged to the paper discharge space 6 is overlapped, and the graph of the example in which the solid line is appropriately corrected, the broken line It is a graph of the example which is curled.

Further, FIGS. 8A to 8F are schematic views showing the state in which the paper P is discharged from the discharge portion 46a with time, but excessive curl correction is performed on the paper P as compared with FIG. This is an example of the case where reverse curl occurs.
In the example shown in FIG. 8, since the paper P is reversely curled, the direction of the edge of the paper P hangs down from the middle with its own weight while being reversely curled during the transition from FIG. 8A to FIG. 8B. The curve is reversed and the cross section starts to show a substantially S shape.
8 (e), the vicinity of the end of the paper P (not necessarily the end depending on the degree of reverse curl) finally comes into contact with the discharge tray 49, but has a complicated cross-sectional shape in which the reverse curl portion remains. ing.

FIG. 9 shows an example of temperature transition measured along each transition state in FIG. 8, as in the combination of FIG. 3, FIG. 4, and FIG. 5, or the combination of FIG. 6 and FIG. Is a graph. In FIG. 9, the graph example shown in FIG. 7 is overlapped, the graph in the example in which the solid line is appropriately corrected, the graph in the example in which the broken line is curled, and the graph in the example in which the one-dot chain line is reversely curled It is.
As shown in FIG. 9 (and FIG. 7), when the temperature distribution of the paper P being discharged (conveyed) is measured around the discharge portion 46a by the thermopile 45, the transition graph shows the curl state (correction) of the paper P. It becomes a peculiar shape according to (degree).

  Therefore, in the present embodiment, as described above, temperature transition (temperature distribution) data in the case where the paper P is appropriately curled in advance or all or a part of the image data in this case (sufficient to determine the tendency of the image). Data obtained by combining predetermined excerpt data) with temperature transition is stored in the storage unit 52. Then, after the image is actually formed according to an instruction from the operation unit 51 or the like, the curled state of the discharged paper is detected, and the control unit 5 applies a feedback (feedback) for controlling the curl correction amount to the curl correction unit 44. .

FIG. 10 is a flowchart illustrating an example of the flow of a processing procedure in the present embodiment. The processing of this embodiment is roughly divided into “initial setting” from Step 11 to Step 15 and “image formation” from Step 21 to Step 28.
The initial setting process is performed at the time of shipment from the factory, for example, when paper or toner of a new composition is used, or during regular maintenance, it is recognized that the curl or reverse curl of the discharged paper has become prominent It may be performed only in The image forming process is performed when there is an instruction to start image formation (reading or copying of an original) via the operation input switches (operation unit 51), or externally via a LAN (Local Area Network) or a printer interface. This process is started when image data is sent from the computer of FIG. 1, when an image is sent via a FAX modem.

  In the initial setting process shown in FIG. 10, the reference image read by the document reading unit 2 as Step 11 or read from the storage unit 52 (see FIG. 2 and the like) is formed and fixed on the paper P, and is discharged from the discharge unit 46a. Discharge. At this time, as Step 12, the temperature distribution of the discharged paper P is measured by the thermopile 45.

In Step 13, it is determined whether or not the curl of the discharged paper is equal to or less than a predetermined amount (determined from the maximum amount that the paper floats from the upper surface of the paper discharge tray). The temperature distribution data of the paper measured as Step 14 is stored in the storage unit 52 as reference temperature transition data.
If the curl of the discharged paper exceeds a predetermined amount at Step 13, the curl correction amount is adjusted at Step 15 and the process returns to Step 11.
In this way, the process of determining the temperature distribution and curl correction amount on the paper and storing it in the storage unit 52 when the curl of the paper discharged after image formation / fixing is properly corrected is the initial setting process. After the initial setting process is completed, the control unit 5 waits for an image formation instruction.

The control unit 5 starts image formation upon receiving an image formation instruction. When an image formation instruction is received, image formation / fixing / discharge is continued (continuous or intermittent) and n times (n is an integer of 1 or more, that is, once, twice, three times, etc.). For convenience, n is 1 here.
As the next step 21, the image read by the document reading unit 2, the image data read from the storage unit 52, and the image data sent via the LAN, printer interface, or FAX modem are formed and fixed on the paper P. In Step 22, the nth discharge is performed from the discharge unit 46a. At this time, as Step 23, the temperature distribution of the discharged paper P is measured by the thermopile 45.

  In Step 24, the temperature distribution of the discharged paper P is compared with the reference temperature transition data read from the storage unit 52. If the difference between the two is equal to or less than the predetermined value, it is determined that the curl correction amount is an appropriate value, and the process proceeds to Step 25 to form and fix the next image on the paper P (or image formation). The system waits for an instruction, and when there is an instruction for the next image formation, the image is formed and fixed on the paper P), and the process returns to Step 22.

  Alternatively, this operation is performed only when the paper tray 40 is clearly opened and the composition of the paper P may be changed immediately after the power is supplied to the copying machine 1 or after waiting for an image formation instruction for a long time. The curl correction amount may be adjusted as in the above embodiment. In this case, this stage is set to Step 25 ′, and the next process or instruction is awaited without returning to Step 22.

On the other hand, when the difference between the temperature distribution of the discharged paper P and the reference temperature transition data read from the storage unit 52 exceeds a predetermined value at Step 24, the temperature distribution of the discharged paper P is determined as Step 26 from the temperature distribution of the discharged paper P. It is determined whether or not P is reverse curled.
If it is determined in step 26 that the paper P is reversely curled, the curl correction amount is reduced and stored in the storage unit 52 in step 27, and the process proceeds to step 25. If it is determined in Step 26 that the curl correction amount for the paper P is insufficient, the curl correction amount is increased and stored in the storage unit 52 in Step 28, and the process proceeds to Step 25.

  Further, in Step 24, the above-described processing may be repeated until the difference between the temperature distribution of the discharged paper P and the reference temperature transition data read from the storage unit 52 becomes a predetermined value or less. Even in this case, if the difference between the temperature distribution of the discharged paper P and the reference temperature transition data read from the storage unit 52 is equal to or smaller than a predetermined value, this stage is set to Step 25 ′, and the process proceeds to the next process without returning to Step 22. Transition.

In this way, in this embodiment, the temperature distribution of the paper with the curl properly corrected is measured and stored as a reference temperature transition, and after image formation, the image is fixed and discharged by heating and pressing. The temperature distribution of the paper is measured by a temperature sensor such as a thermopile, and the curl correction amount is adjusted so that the temperature distribution approaches the reference temperature transition data.
Further, after the curl correction amount is adjusted once in this way, the temperature distribution of the discharged paper is measured by a temperature sensor such as a thermopile, and the curl correction amount can be adjusted again so that the temperature distribution approaches the reference temperature transition data. .
That is, the curl correction state is grasped from the temperature distribution of the discharged first sheet, and the curl correction state is fed back to the curl correction amount, whereby the second sheet, the third sheet and thereafter (n is 2 or later) are discharged. This is to suppress the curling of the paper, and is characterized in that it can be converged to an appropriate state even if the amount of correction is large and reverse curl is generated.

In addition, when reverse curl occurs in the discharged paper, the temperature difference between the heat roller and the press roller in the fixing unit is affected. Therefore, this temperature difference can also be fed back to the curl correction amount.
FIG. 11 is a diagram illustrating a configuration for feeding back a temperature difference between the heat roller and the press roller. In the configuration shown in FIG. 11, a thermistor 42d as an example of a temperature detection unit is incorporated in a press roller 42c as an example of a second roller.

In general, since the heat roller has a kind of temperature sensor, according to the configuration shown in FIG. 11, the temperature difference between the heat roller 42a and the press roller 42c can be grasped.
The control unit 5 adjusts the correction amount by the curl correction unit 44 based on the temperature distribution on the paper P measured by the thermopile 45, and also adjusts the temperature distribution on the paper P and the temperature difference between the heat roller 42a and the press roller 42c. Based on this, the curled state or reverse curled state of the paper P is grasped, and the heat generation amount and the rotation speed of the heat roller 42a are controlled.
Thereby, for example, even when the curl of the discharged paper is not constant and the reverse curl partially occurs, the curl and reverse curl of the paper can be suppressed more finely.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. For example, even if it is a printer other than a dry electrophotographic copying machine, if the printing machine has a correction unit that restores the warp generated in the recording medium by various internal processes by pressurization, the temperature distribution on the discharged recording medium Is within the scope of the present invention.

Further, the graph shape of the temperature distribution used in the above description is an example, and when the present invention is applied, the composition of the paper, the detailed characteristics of the temperature sensor, the shape of the paper discharge tray, the discharge portion, and the like. Different temperature distribution shapes are derived in accordance with the distance relationship.
Therefore, for example, if it is decided by a producer or the like to use paper whose composition and characteristics are guaranteed to be constant, the temperature change data of the paper is also stored in the ROM area of the storage unit 52 in this embodiment. It can also be set as a structure to memorize. In this case, the user of the present embodiment only needs to specify the paper to be used from the operation unit 51 or the like without performing the above-described initial setting process. Although not shown in the drawings, there is provided means for printing a code unique to the paper on a part of the paper with a pigment or the like that does not impair the formed image and reading the code around the paper tray 40. Accordingly, there is no need for the user to perform an operation for designating the paper, and a configuration error can be eliminated.
Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a number, position, shape, and the like that are suitable for implementing the present invention. In each figure, the same numerals are given to the same component.

1 Copying machine (image forming device)
2 Document Reading Unit 4 Body Unit 5 Control Unit 6 Paper Discharge Space 40 Paper Tray 41 Image Forming Unit (Transfer Unit)
42 Fixing part 42a Heat roller 42b, 42c Press roller 42d Thermistor 43 Photo interrupter (position sensor)
44 Curl correction unit 45 Thermopile (temperature sensor)
46a Ejection unit 46b Ejection unit for double-sided printing 49 Ejection tray 51 Operation unit 52 Storage unit 53 Calculation unit P Paper

Claims (5)

An image is formed on a recording medium, and a deformation that may occur on the recording medium during the image forming process is corrected by a correction process including a partial heating process or a pressing process, or both a heating process and a pressing process, and a correction amount. An image forming apparatus that performs correction processing and discharges by a correction unit that can vary
A heat detection unit capable of detecting temperatures of a plurality of predetermined portions of the recording medium immediately after being discharged;
Comprising an arithmetic unit for calculating the temperature distribution information group in a predetermined surface of the recording medium based on the temperature of the predetermined plurality of sites, and a storage unit for storing reference temperature distribution information group,
The calculation unit calculates a temperature distribution information group of temperatures detected by the heat detection unit in a state where the deformation that has occurred in the discharged recording medium is corrected to an appropriate state by the correction unit, and the reference temperature distribution Memorize | store in the said memory | storage part as an information group,
Each time the recording medium on which the image is formed and corrected is discharged, the calculation unit calculates a temperature distribution information group of temperatures detected by the heat detection unit, and the reference temperature distribution information group is a measurement temperature distribution information group. And the correction amount by the correction unit is changed so as to approximate the arrangement state of the measured temperature distribution information group to the arrangement state of the reference temperature distribution information group . An image is formed on a recording medium, and a deformation that may occur on the recording medium during the image forming process is corrected by a correction process including a partial heating process or a pressing process, or both a heating process and a pressing process, and a correction amount. An image forming apparatus that performs correction processing and discharges by a correction unit that can vary
A heat detection unit capable of detecting temperatures of a plurality of predetermined portions of the recording medium immediately after being discharged;
A calculation unit that calculates a temperature distribution information group on a predetermined surface of the recording medium based on the temperatures of the predetermined plurality of parts, and a storage unit that stores a reference temperature distribution information group,
The calculation unit calculates a temperature distribution information group of temperatures detected by the heat detection unit in a state where the deformation that has occurred in the discharged recording medium is corrected to an appropriate state by the correction unit, and the reference temperature distribution Memorize | store in the said memory | storage part as an information group,
Until the difference between the arrangement of pre-Symbol measured temperature distribution information group the temperature distribution information group temperature detected by the arrangement of the reference temperature distribution information group the heat sensing portion is calculated the arithmetic unit approaches a predetermined range, Each time the recording medium on which the image is formed and corrected is discharged, the correction amount by the correction unit is changed so as to approximate the arrangement state of the measured temperature distribution information group to the arrangement state of the reference temperature distribution information group. images forming apparatus you and repeating the process. A correction discharge unit for discharging the recording medium subjected to the image forming process and the correction process;
The heat detection unit is attached to a peripheral part at a predetermined distance from the correction discharge unit, and detects the temperature of a predetermined surface of the recording medium or a part of the predetermined surface in a non-contact manner. the image forming apparatus according to claim 1 or 2. The image formed on the recording medium as the correction unit is heated, pressurized, or heated with a first roller that contacts the first surface of the recording medium and a second roller that contacts the second surface. A fixing unit to be fixed by a fixing process by both pressure processes;
A correction unit that performs correction processing on the recording medium that is inwardly curved toward the first or second surface by the fixing process;
If the inner surface of the curved by the correction process based on the difference between the sequence state before Symbol reference temperature distribution information group and arrangement of the measured temperature distribution information group is determined to have reversed, the correction amount by the correction unit The image forming apparatus according to claim 1 , wherein the image forming apparatus is reduced. The first of the with the heating the recording medium calorific or rotational speed together the temperature detecting portion is provided inside the first roller that can be controlled consists of a second roller for pressing the recording medium the recording medium Alternatively, a fixing unit that fixes the image formed on the second surface by a heat treatment or a pressure treatment or a fixing treatment by both heat and pressure treatments;
A correction unit that performs correction processing on the recording medium that is inwardly curved toward the first or second surface by the fixing process;
Have
If the inner surface of the curved by the correction process based on the difference between the sequence state before Symbol reference temperature distribution information group and arrangement of the measured temperature distribution information group is determined to have reversed, the said first roller The image forming apparatus according to claim 1, wherein the heat generation amount and the rotation speed of the first roller are controlled so that a temperature difference with the second roller is small.

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