JP2009175422A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which, while measuring a deflection state of a recording material on which an image is to be formed in conveyance of the recording material in an upward direction between the transfer and fixation thereof, performs stable conveyance of the recording material without incurring oblique running and paper jamming in conveying the recording material, and thereby provides an image having parallelism. <P>SOLUTION: The image forming apparatus 1 reads the disturbance of the balance of the recording material P as the deflection positional information of the recording material by measuring the positions of the left and right end portions of the recording material P by using ranging sensors 91 and 92, and changes the positional relation (alignment) of a fixing device 60 or a transfer device 10 so that the difference in the position is reduced, thereby keeping image parallelism. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a recording material such as a copying machine, a printer, and a fax machine using an electrophotographic method.

In recent years, in image forming apparatuses such as printers, copiers, and facsimiles, space-saving and high-speed and high-quality machines are desired. For this reason, the paper path of the part that forms the image from the part that feeds the paper as the recording material is set in the vertical direction, which is the vertical direction, and is not discharged to the outside of the image forming apparatus but is provided inside. There is a tendency that the number of machines that discharge paper into the inner space increases.
However, in a machine with a vertical conveyance path, if there is no suction belt that forcibly holds the paper to be conveyed, due to the force such as gravity acting on the paper or air current flowing inside the machine, The state of the paper is not stable, and the recording material such as paper may bend between the transfer portion and the fixing portion where the image is formed or between the transfer portion and the resist portion.

Also, in the transfer part that forms the image, the registration part before and after the transfer part, and the fixing part, right and left manufacturing errors such as rollers, pressure deviations, mounting position errors, and positional deviations such as guide plates that restrict paper movement As a result, the difference between the left and right movements of the paper is likely to occur. These differences result in an influence on a transfer portion that forms an image, and become a factor that disturbs the parallelism of the image.
Further, if the pressure at the transfer portion is forcibly increased to stabilize the paper state, there will be no paper escape space between the transfer and fixing, causing paper wrinkles and the like.
As a method for correcting this parallelism, there has been proposed a means for printing an image once as in Patent Document 1 and Patent Document 2, and taking the result of the image into a reading device and correcting the image. However, this method requires an operation for printing and reading an image each time. For this reason, it is difficult to cope with the change due to the deformation during the use period of the roller or the like and the change including the friction due to the difference in the type of paper used.
Further, when the suction belt for forcibly holding the paper to be conveyed is provided, it is possible to suppress the bending of the recording material, but the belt, the rotating member, the motor for performing the suction, and the high pressure. Cost is required.
Also, these are paper conveyances in the horizontal direction, which adjust the parallelism, squareness, image magnification, etc. in transfer or superimposition, and adjustments related to the image position. It does not control the bending of the conveyance in the upward direction of the material.

Japanese Patent Application No. 2003-414553 Special No. 3867675

  Therefore, the present invention has been made in view of the above-mentioned problems, and the problem is that the recording material is measured while measuring the state of bending in the upward conveyance between the transfer and fixing of the recording material forming the image. It is an object of the present invention to provide an image forming apparatus that can perform stable conveyance without skew or paper jam in conveyance and obtain an image with parallelism.

The features of the present invention, which is a means for solving the above problems, are listed below.
An image forming apparatus according to the present invention includes a transfer device in which a rotating transfer member abuts against a carrier on which a toner image is carried, and transfers the toner image to a recording material conveyed by the transfer member; In an image forming apparatus having a fixing device in which a recording material having a transferred toner image is conveyed in a vertical direction and fixed by a heat fixing member, recording conveyed to a portion between the transfer device and the fixing device A control unit that includes a measuring unit that measures the bending state of the recording material with respect to the upward conveyance of the material, and that calculates the bending state of the recording material at the two left and right end portions obtained from the measuring unit; According to the result, the position of the transfer device or the fixing device is changed to adjust the bending state.
Alternatively, the image forming apparatus of the present invention may further include the transfer device and / or the fixing device based on a result of a control unit that calculates a bending state of the recording material at the two left and right end portions obtained from the measuring unit. It is characterized by changing the speed of the apparatus and adjusting the bending state.
Alternatively, the image forming apparatus of the present invention is further characterized in that the bending state is adjusted from the result of calculating the bending state of the left and right two portions of the recording material for each sheet or a plurality of predetermined recording materials.
Alternatively, the image forming apparatus of the present invention is further characterized in that the deflection state is adjusted when the average value of the deflection results of the left and right two portions of the recording material for each sheet or a plurality of sheets exceeds an allowable limit. .
Alternatively, the image forming apparatus of the present invention further sets a permissible limit by a combination of the paper feed cassette and the paper size, and each sheet or a plurality of sheets when the paper feed cassette is mounted or the paper size is changed. When the average value of the results of bending of the left and right two recording materials exceeds an allowable limit, the bending state is adjusted.
Alternatively, the image forming apparatus according to the present invention is further characterized in that a new allowable limit is set from the average value of the results of bending of the left and right two portions of the newly obtained one or plural recording materials. .

The present invention, which is a means for solving the above problems, has the following specific effects.
In the image forming apparatus of the present invention, it is possible to change the mounting alignment position of transfer or fixing, and to constantly monitor the state of bending or twisting of the recording material being conveyed, and the bending exceeding the allowable limit occurs. It is possible to predict image parallelism problems and wrinkles that occur when the image is read without reading the result of the image, and to provide an image forming apparatus that stably conveys the recording material. It becomes possible.
In addition, it is possible to provide an appropriate relative speed with respect to the deformation generated in the rollers of the transfer device and the fixing device of the image forming apparatus that has been used for a long time. It is possible to prevent image defects caused by recording material splashes.
Furthermore, when the sheet feeding cassette device is opened, it can be predicted that another type of recording material has been set, and the setting can be changed according to the recording material.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

Next, FIG. 1 is a schematic view showing a configuration of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, a color image forming apparatus 1 includes a transfer device 10 having an intermediate transfer belt 11 and four image stations. Each image station has an image carrier (hereinafter referred to as a photosensitive drum) 20Y, 20C, 20M, and 20Bk. There are dedicated charging devices 30Y, 30C, 30M, 30Bk, developing devices 50Y, 50C, 50M, 50Bk, and cleaning devices 40Y, 40C, 40M, 40Bk.
A toner bottle for replenishing toner, which is filled with toners of yellow (Y), cyan (C), magenta (M), and black (Bk) from the left in the figure. The developing devices 50Y, 50C, 50M, and 50Bk for each color are replenished by the replenishment amount.
Regarding the operation, the recording material P as a recording medium is fed from the paper feed cassette 81 by the paper feed roller 82, and when the leading end of the recording material P reaches the registration roller pair 83, it is detected by a sensor (not shown). The recording material P is conveyed to the nip portion between the secondary transfer roller 15 and the intermediate transfer belt 11 by the registration roller pair 83. The photosensitive drums 20Y, 20C, 20M, and 20Bk, which are uniformly charged in advance by the charging devices 30Y, 30C, 30M, and 30Bk, are exposed and scanned by the exposure device 70 with laser beams 71Y, 71C, 71M, and 71Bk. An electrostatic latent image of yellow (Y), cyan (C), magenta (M), and black (Bk) is formed on the drums 20Y, 20C, 20M, and 20Bk.

The electrostatic latent images are developed by the developing devices 50Y, 50C, 50M, and 50Bk for the respective colors, and yellow, cyan, magenta, and black toner images are formed on the surfaces of the photosensitive drums 20Y, 20C, 20M, and 20Bk. The intermediate transfer belt 11 having no drive starts to be driven by the frictional force with the photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers that have started rotating, and then the primary transfer rollers 12Y, 12C, 12M, and 12Bk. A voltage is applied to the photosensitive drums 20Y, 20C, 20M, and 20Bk, and the toner is sequentially transferred onto the intermediate transfer belt 11. At this time, the image forming operation for each color is executed while shifting the timing from the upstream side toward the downstream side so that the toner image is transferred to the same position on the intermediate transfer belt 11.
The image formed on the intermediate transfer belt 11 is conveyed to the position of the secondary transfer roller 15 and is secondarily transferred to the recording material P. The recording material P on which the toner images of the respective colors are transferred is conveyed substantially vertically toward the fixing device 60 provided above. The transport direction may not be the vertical direction, but the image forming apparatus can be downsized in the vertical direction, and the transport distance is shortened, so that the time for the image forming operation can be shortened.
The recording material P is conveyed to the fixing device 60 and is fixed by heat and pressure in a fixing region formed between the pressure roller 61 and the fixing roller 62 and is discharged by the paper discharge roller 84. Thus, one image forming job is completed.
The residual toner on the photoconductive drums 20Y, 20C, 20M, and 20Bk is cleaned by the respective cleaning devices 40Y, 40C, 40M, and 40Bk, and then the charging device 30Y, in which the bias of the AC component is superimposed and applied to the direct current. 30C, 30M, and 30Bk are charged at the same time as static elimination to prepare for the next image forming job. The residual toner on the intermediate transfer belt 11 is cleaned by the elastic intermediate transfer belt cleaning device 14 to prepare for the next image forming job.

FIG. 2 is an image forming apparatus according to an embodiment of the present invention, and is a schematic diagram illustrating a configuration between a transfer roller and a fixing device.
Among the color electrophotographic apparatuses that have been increasing in recent years, a diagram of a tandem type apparatus in which four image forming apparatuses are arranged and a recording material is conveyed vertically is shown. As described above, the recording material P is fed from the paper feed cassette 81 and contacts the intermediate transfer belt 11 after passing through the registration roller 83. The intermediate transfer belt 11 on which the color image is formed enters the nip portion with the secondary transfer roller together with the recording material P, and moves from the intermediate transfer belt 11 to the recording material P by a bias applied to the secondary transfer roller 15. . Further, the recording material onto which the toner image has been transferred is directed to the fixing device 60 and is heated and pressed by the fixing roller 62 and the pressure roller 61 to depict the image on the recording material P.

Here, as described above, an image is formed on the recording material P by the secondary transfer roller 15, but unfixed toner is applied to the recording material between the transfer nip portion of the secondary transfer roller 15 and the fixing device 60. In some cases, it cannot be positively held on the image side. The conveyance of the recording material P in the upward direction (hereinafter referred to as “longitudinal conveyance”) in the drawing of FIG. If the image forming apparatus 1 is not such a vertically transported image forming apparatus 1 but is transported horizontally in the horizontal direction (hereinafter referred to as “horizontal transport”), an unfixed toner image is placed on the top. Although it is possible to feed the lower side of the recording material P in accordance with the gravity with a conveying belt or the like, in the case of vertical conveyance, the movement of the paper is disturbed due to the influence of the gravity or the internal air current, and the paper is skewed. In some cases, the paper is not conveyed to the fixing nip portion between the fixing devices 60 and becomes jammed.
Generally, a guide plate or the like for assisting the conveyance of the recording material P toward the non-image surface between the transfer nip portion of the secondary transfer roller 15 and the fixing device 60 may be provided. When the recording material collides with the plate, the balance may be lost, causing skew and paper jam.

This disturbance in the balance of the movement of the recording material P becomes an image formation disorder in the transfer nip portion of the secondary transfer roller 15. For example, the non-uniformity around the guide plate described above becomes a conveyance load of the recording material. The image parallelism is disturbed by a slight change in the transfer time of the image to the recording material.
Further, regarding the image formation on the recording material P, the dimensions of the outer diameters of the secondary transfer roller 15 and the rollers 61 and 62 of the fixing device 60 are greatly related. For example, when the outer diameter of the fixing roller 62 for secondary transfer is different between the left end portion and the right end portion of the recording material, the paper feed speed becomes slower on the thin outer diameter side. The produced image is stretched when transferred to the recording material. Similarly, when the fixing roller 62 and the pressure roller 61 of the fixing device 60 have different roller diameters at the left end and the right end, the image is affected.

Depending on the magnitude of the pressure of the secondary transfer roller 15 and the fixing device 60, that is, the balance of the conveying force with respect to the recording material P, the slip factor of the recording material P, or the secondary which is the target two rollers, respectively. The phenomenon varies depending on which of the transfer roller 15, the secondary transfer unit, the intermediate transfer belt unit roller 12, the fixing roller 62, and the pressure roller 61 has a force for conveying the recording material. There is no change in influencing.
Therefore, in the image forming apparatus 1 of the present invention, the balance of the recording material P is read as the positional information of the deflection of the recording material using the distance measuring sensors 91 and 92 at the positions of the left end and the right end of the recording material P. The image parallelism is maintained by the change in the positional relationship (alignment) of the fixing device 60 or the transfer device 10 so as to reduce the difference.

FIG. 3 is a schematic diagram showing the arrangement of distance measuring sensors that take in the positional information of the recording material in the image forming apparatus of the present invention. FIG. 4 is a graph showing an output example of the distance measuring sensor. FIG. 5 is a schematic view showing the relationship between the position of the control unit that captures the output of the distance measuring sensor and the position of the recording material and the output value.
In the image forming apparatus of the present invention, as a measuring means for measuring the bending state of the recording material P with respect to the upward conveyance of the recording material P conveyed to the portion between the secondary transfer roller 15 and the fixing device 60. Distance sensors 91 and 92 are provided. As shown in FIG. 3, the distance measuring sensors 91 and 92 are positions where the left end portion and the right end portion of the recording material P can be measured, and between the secondary transfer roller 15 and the fixing device 60 that are easily affected by the image parallelism. Are arranged at two positions where the measurement can be performed.
A signal representing the bending state of the recording material P at the two left and right end portions obtained from the sensors 91 and 92 is transmitted to the control unit 93. As shown in FIG. 5, the control unit 93 includes an A / D converter 94 that converts a signal into data, a storage unit 95 that stores the data, and an arithmetic processing unit 96 that performs calculation using the data in the storage unit 95. Is arranged.
As shown in FIG. 4, the output of this sensor is a type of sensor that outputs an output having a correlation with the sensor output such that the output voltage decreases as the distance increases and increases as the distance decreases. When the recording material P is placed on the third distance measuring sensor 91, 92 side, the output is high, and when the recording material P is separated, the output is low.

At this time, if the output of the distance measuring sensor 91 at the left end is POS1 and the output of the distance measuring sensor 92 at the right end is POS2 with respect to the conveying direction of the recording material P of the image forming apparatus 1, the two outputs are the conveying direction of the recording material. In contrast, outputs POS11, 12, 13... 1n and POS21, 22, 23. Further, this output becomes position information Dpos11, 12, 13... 1n and Dpos21, 22, 23... 2n having a predetermined interval by the A / D converter 94 of the control unit 93, and is for the sub-scan of the recording material P. The data is stored in the storage unit 95 as data. The stored data is subjected to a difference so as to be the result of the left and right deflection states, and converted into deflection information Ddef1, Ddef2,.
FIG. 6 is a schematic diagram illustrating a state in which the recording material is bent between the transfer roller and the fixing device. (A) shows the state where it is not bent at both left and right ends, and (b) shows the state where it is bent at both left and right ends.
In the state (a), the difference between the left and right ends is zero. In other words, at this time, the ideal transport state is the state where the bending state is always the same, that is, the most ideal state when Ddef is 0 at any position. However, when the bending occurs, the state collapses. become.
The state of (b) is a simplified representation of the state of the recording material at that time when there is a difference in the left and right outer diameters of the fixing roller or pressure roller as an example of a state where there is bending. is there.

Assuming that the left and right ejection states and speed states of the recording material P of the secondary transfer roller 15 are the same, and that the recording material P is not subjected to any guide plate or external factors, the recording material P is transferred from the secondary transfer roller 15 to the fixing device 60. It is conveyed in the same state until the time of entry. At this time, assuming that the position in the transport direction until the fixing approach is t, Ddef1, Ddef2,. However, when the recording material P is sandwiched between the fixing roller 62 and the pressure roller 61, basically, when the outer diameter difference 61 ′, 62 ′ is generated, the recording material P is fed differently, as shown in FIG. When it occurs on the left and right of the state and the state of (b), it becomes a difference in deflection of the recording material P and appears from Ddeft + 1 to Ddefn where the recording material P passes through the secondary transfer roller 15.
As described above, the influence on the final image differs depending on the pressure of the secondary transfer roller 15 and the fixing device 60, that is, the balance of the conveying force with respect to the recording material P and the slip factor of the recording material P. However, this bending appears as a difference in the parallelism of the images, but the state is recorded in the recording unit 95 in the control unit 93.

Next, a means for correcting this bending state will be described. In the image forming apparatus of the present invention, the bending state of the recording material P at the two left and right end portions obtained from the distance measuring sensors 91 and 92 is changed by changing the positions of the secondary transfer roller 15 and the fixing device 60. Adjust the condition. Although not shown, it is possible to change the position of the secondary transfer roller 15 by adjusting the positions of the bearings provided at both ends that are pivotally supported. In particular, even if the intermediate transfer belt 11 with which the secondary transfer roller 15 is in contact is moved between two stretched rollers 12 and the position thereof is changed, the intermediate transfer belt 11 is brought into contact without greatly changing the contact conditions. Can do.
FIG. 7 is a schematic diagram for explaining a change in the position of the fixing device.
In order to slide the position of the fixing device 60, as shown in FIG. 7, the height of the positioning member 63 that holds the fixing device 60 is rotated by a gear 67 having an eccentric mechanism to which the drive of the motor 68 is transmitted. As a result, the position of the fixing device 60 can be slid. At this time, the positioning member 63 is moved by shifting the height of the positioning portion 64 opposite to the direction in which the fixing device 60 is driven along the side plates 65 and 66 without greatly shifting the gear drive engagement. Can be achieved.
In addition, the bending of the recording material P is corrected by moving the fixing device 60 in the vertical direction. However, various other methods are conceivable, and the fixing device 60 is slid in the horizontal direction or the transfer device. The method of changing the position of 10, the pressure of the secondary transfer roller 15 is changed, or the position of the guide plate of the recording material P of the transfer device 10 -fixing device 60 not shown is controlled. It is possible to correct the deflection.

FIG. 8 is an example of the output voltage of the distance measuring sensor when the position of the fixing device is changed. By sliding the position of the fixing device 60, the positional relationship with the secondary transfer roller 15 changes, the state of the recording material P entering, the speed, etc. change, and the entering angle with respect to the feeding direction also changes. To do. Therefore, the solid line in the figure is the case where the position of the fixing device 60 is changed upward, and the broken line is the case where the position of the fixing device 60 is changed upward. By moving the fixing device 60 up and down, the approach angle of the recording material P is changed, and the state of bending is also changed. As shown in FIG. 8, it can be confirmed that the output difference between the distance measuring sensors 91 and 92, that is, the deflection of the recording material P changes and becomes smaller. As a result, it is understood that the amount of bending of the recording material P can be reduced, and the conveyance of the recording material P and the parallelism of the image on the recording material P can be corrected.
By controlling this change so that the values of the deflection information Ddef1, Ddef2,... Ddefn at the above-described positions return to 0, it becomes possible to adjust the parallelism. At this time, the position deflection information Ddef can be adjusted even with only one result. However, in order to maintain more accuracy, it is preferable to carry out an average of a plurality of results.

Next, in the present invention, the deflection can be adjusted by adjusting the relative speed between the transfer device 10 and the fixing device 60 using the distance measuring sensors 91 and 92.
Durability is one of the major problems in image formation of the image forming apparatus 1. However, when the various rollers shown here are used for a long period of time, the outer diameter of the rollers changes. If it is a metal type roller, a big problem will not generate | occur | produce, but if it is a sponge type, the possibility of causing those problems increases.
As shown in FIG. 6, the change in the position of the pressure roller 61 and the fixing roller 62 in the fixing device 60 appears in the bending of the left and right ends of the recording material P. This fluctuation does not occur uniformly on the left and right, but as an overall change, the outputs Dpos11, 12, 13,... When the control unit 93 calculates 22, 23... 2n, the overall position variation can be captured. At this time, when the overall position fluctuation output is ALLDpos 1, 2,..., N, when it is determined that the value of ALLDposn exceeds a certain allowable limit M, the speed is corrected.
For example, as shown in FIG. 6B, when the diameter of the fixing roller 62 decreases and the speed decreases, the rotational speed of the fixing roller 62 is increased so as to return to the state of FIG. When the allowable limit M is exceeded, a phenomenon occurs in which the recording material P jumps when it hits a guide plate (not shown) and the recording material P is no longer escaped. By storing it, it becomes possible to maintain an appropriate state.
Therefore, the deflection is adjusted when each of the deflections Dpos1n and Dpos2n exceeds a predetermined allowable limit. Further, the outputs Dpos1n and Dpos2n are regarded as an average of a plurality of deflections instead of each Dpos1n and Dpos2n, and the deflection is adjusted when the average exceeds an allowable limit. When one sheet is bent, there is a variation in strength of the recording material P, the adjustment frequency is increased, and the image forming operation may be hindered.

  The recording material P of the electrophotographic apparatus 1 is replenished as needed by the user who is using it. In general, when the recording material P before replenishment and the recording material P after replenishment become large, the user registers the recording material type to be newly replenished, but it is also possible to forget to register, etc. It is done. At this time, the parallelism of the image and the relative speed of the transfer device and the fixing device may change greatly. On the other hand, since the electrophotographic apparatus can recognize that the user has performed the operation with the opening / closing sensor at the time of replenishment, the deflection information Ddef of the position before and after that and the overall position change When it is confirmed that ALLDpos has changed, an adjustment operation is performed. This adjustment operation can also be adjusted with only one result as described above. However, in order to maintain more accuracy, it is preferable to perform an average operation from a plurality of results.

  Further, the image forming apparatus 1 sets an allowable limit by a combination of the paper feed cassette 81 and the size of the recording material P. When the paper feed cassette 81 is mounted or the size of the recording material P is changed, one sheet is formed. When the average value of the results of bending of the left and right two positions of each recording material or a plurality of sheets exceeds the allowable limit, the bending state is adjusted. There is a machine-to-machine difference in the image forming apparatus 1, and there is also a machine-to-machine difference in the combination of the paper feed cassette 81 and the image forming apparatus 1. At this time, an allowable limit is set in advance, in which bending occurs and the parallelism of the image decreases. As a matter of course, the image forming apparatus 1 is set so that the image forming operation without deflection is in a standard state in advance. However, in the image forming apparatus 1, when the user installs the paper feed cassette 81 in order to replenish a new recording material P or changes the size of the recording material P, the conveyance state of the recording material P changes and the bending is caused. May occur. In severe cases, paper jams can occur. Therefore, when the paper feed cassette 81 is mounted or when the size of the recording material P is changed, the bending of the recording material P is measured to adjust the bending. As a result, the occurrence of a paper jam can be suppressed.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. 1 is an image forming apparatus according to an exemplary embodiment of the present invention, and is a schematic diagram illustrating a configuration between a transfer roller and a fixing device. FIG. 3 is a schematic diagram showing an arrangement of distance measuring sensors that take in positional information of a recording material in the image forming apparatus of the present invention. It is a graph which shows the example of an output of the distance measuring sensor. It is the schematic which shows the control part which takes in the output of the distance sensor, and the relationship between the position of a recording material, and an output value. FIG. 6 is a schematic diagram illustrating a state in which a recording material is bent between a transfer roller and a fixing device. FIG. 6 is a schematic diagram for explaining a change in the position of the fixing device. It is an example of the output voltage of a ranging sensor when the position of the fixing device is changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Transfer apparatus 11 Intermediate transfer belt 12 Stretching roller 13 Primary transfer roller 14 Belt cleaning apparatus 15 Secondary transfer roller 20 Photosensitive drum 30 Charging apparatus 40 Cleaning apparatus 50 Developing apparatus 51 Developing sleeve 60 Fixing apparatus 61 Pressure Roller 62 Fixing roller 63 Positioning material 64 Opposite positioning part 65, 66 Side plate 67 Gear 68 Motor 70 Exposure device 71 Laser beam 80 Paper feed device 81 Paper feed cassette 82 Paper feed roller 83 Registration roller 84 Paper discharge roller 91, 92 Sensor 93 Control unit 94 A / D converter 95 Storage unit 96 Arithmetic processing unit P Recording material

Claims (6)

A transfer device in which a rotating transfer member abuts against a carrier on which a toner image is carried, and the toner image is transferred to a recording material conveyed by the transfer member;
An image forming apparatus having a fixing device in which the recording material having the transferred toner image is conveyed in a vertical direction and fixed by a heat fixing member;
A measuring unit that measures a bending state of the recording material with respect to the upward conveyance of the recording material conveyed to a portion between the transfer device and the fixing device;
The position of the transfer device or the fixing device is changed and the bending state is adjusted according to the result of the control unit that calculates the bending state of the recording material at the two left and right ends obtained from the measuring means. Image forming apparatus. The image forming apparatus according to claim 1,
The image forming apparatus changes the speed of the transfer device and / or the fixing device based on the result of the control unit that calculates the bending state of the recording material at the two left and right end portions obtained from the measuring unit. An image forming apparatus characterized by adjusting a bending state. The image forming apparatus according to claim 1, wherein
The image forming apparatus adjusts the bending state based on the result of calculating the bending state of two left and right positions of the recording material for each sheet or a plurality of predetermined recording materials. The image forming apparatus according to claim 3.
The image forming apparatus adjusts the bending state when the average value of the bending results of the left and right two portions of the recording material for each sheet or a plurality of sheets exceeds an allowable limit. The image forming apparatus according to claim 4.
The image forming apparatus sets an allowable limit by a combination of a paper feed cassette and a recording material size,
When the paper cassette is installed or the size of the recording material is changed, the deflection state is adjusted when the average value of the results of bending of the left and right of each recording material or multiple recording materials exceeds the allowable limit. An image forming apparatus. The image forming apparatus according to claim 5.
The image forming apparatus is characterized in that a new allowable limit is set based on the average value of the results of bending of the left and right two positions of each recording material or a plurality of newly obtained recording materials.

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