JP2008233440A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the image quality of an output image higher, without promoting the reduction in productivity, even when fixing process execution speed is made lower than that during normal operation. <P>SOLUTION: An image forming apparatus 1 is configured to include: an image forming unit 10 which forms an image onto an image carrier 15 and transfers the image formed on the image carrier 15 onto a medium P; a fixing unit 20 which fixes the image transferred on the medium P, wherein the fixation is performed selectively according to a plurality of modes whose processing speeds are different from each other; a condition correcting means 40 which corrects an image forming condition in the image forming unit 10, on the basis of the detection result of a patch image formed on the image carrier 15 by the image forming unit 10; and an operation control means 50 which allows the image forming unit 10 to form the patch image on a non-image forming area on the image carrier 15, which is generated due to the processing speed difference between the modes, when the fixing unit 20 corresponds to a low processing speed mode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  Conventionally, an electrophotographic image forming apparatus that forms an image through each process of charging → exposure → development → transfer → fixing has been widely used, but in such an electrophotographic image forming apparatus, In order to achieve high image quality of the output image, a toner patch image is formed on an image carrier such as an intermediate transfer belt at a predetermined timing, and the toner patch image is detected by a detection means such as a sensor. Some are configured to correct image forming conditions such as density adjustment, color reproducibility correction, gradation correction, and the like based on the results (for example, Patent Document 1).

JP 2000-221738

  By the way, in recent years, image forming apparatuses tend to be required to realize high productivity (increase in the number of outputs per hour) in addition to realizing high-quality output images.

  However, in the electrophotographic system, there is a high possibility that the fixing process will first reach its performance limit. For example, when outputting high-quality images such as so-called photographic prints, it may be necessary to form an image on a medium with a large basis weight (weight per unit area). This is because a large amount of power is required for fixing the transferred image on the medium. Therefore, in some electrophotographic image forming apparatuses, the processing speed of the fixing process is required to ensure that the transferred image can be fixed even on a medium having a large basis weight when outputting a high-quality image. Some of them are configured to lower the value than usual.

On the other hand, in order to achieve high image quality of the output image, it is effective to perform toner patch image formation and correction of image formation conditions based on the detection result at a high frequency, for example, for each page of the output image. .
However, since the formation of the toner patch image and the correction of the image forming condition based on the detection result are generally performed at a predetermined timing different from the formation of the output image, increasing the frequency increases the productivity. There is a risk of lowering. In particular, in an image forming apparatus configured to reduce the processing speed of the fixing process as described above, an increase in frequency that promotes a reduction in productivity should be avoided.

  Accordingly, the present invention provides an image forming apparatus that can realize high image quality of an output image without promoting productivity reduction even when the fixing process processing speed is reduced than usual. The purpose is to provide.

The present invention is an image forming apparatus devised to achieve the above object.
According to the first aspect of the present invention, there is provided image forming means for forming an image on an image carrier whose surface is circulated and transferring the formed image on the image carrier onto a medium, and the image formed on the medium. In addition to fixing an image, the fixing selectively corresponds to one of a plurality of modes including a first processing speed mode and a second processing speed mode that is slower in processing speed than the first processing speed mode. Fixing means to be performed, condition correction means for correcting image forming conditions in the image forming means based on the detection result of the patch image formed on the image carrier by the image forming means, and the second processing speed mode The difference in the moving speed of the surface of the image carrier between the first processing speed mode and the first processing speed mode is made smaller than the processing speed difference of the fixing means, and the fixing means enters the second processing speed mode. If corresponding, the image shape An operation for forming the patch image by means using a non-image forming area on the image carrier caused by a processing speed difference between the first processing speed mode and the second processing speed mode. An image forming apparatus comprising a control unit.
According to a second aspect of the present invention, when the moving speed of the surface of the image holding member corresponds to the first processing speed mode even when the fixing unit corresponds to the second processing speed mode, 2. The image forming apparatus according to claim 1, wherein the image forming apparatus operates at the same speed.
According to a third aspect of the present invention, the image forming unit is provided between the second processing speed mode and the first processing speed mode when the fixing unit corresponds to the second processing speed mode. The difference in moving speed of the surface of the image carrier increases the image forming pitch, which is the interval between the images formed on the image carrier, corresponding to the difference in processing speed of the fixing means, and the operation control 3. The patch image according to claim 1, wherein the means causes the patch image to be formed in a non-image forming area formed between the image forming areas by widening the image forming pitch. An image forming apparatus.
The invention according to claim 4 is characterized in that the operation control means forms a plurality of different types of images for each image forming pitch when forming the patch image at the image forming pitch. The image forming apparatus according to 2 or 3.
According to a fifth aspect of the present invention, when the operation control unit is configured to form the patch image by the image forming unit and the condition correction unit associated therewith when the fixing unit corresponds to the second processing speed mode. 5. The image forming apparatus according to claim 1, wherein the frequency of correcting the image forming conditions is higher than that in the first processing speed mode.
The invention according to claim 6 includes a medium conveying unit that receives a medium after image transfer from the image forming unit and sends the medium to the fixing unit, and the medium conveying unit has a function of temporarily waiting the medium. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the fixing unit switches the corresponding mode depending on the type of the medium.

According to the first aspect of the present invention, a patch image is formed by forming a non-image forming area generated on the image carrier due to a difference in processing speed of the fixing unit between modes as an area on the image carrier for the formation. Therefore, it is possible to reduce a decrease in image formation productivity that occurs when the patch image is formed and the image forming conditions are corrected accordingly. Since a non-image forming area on the image carrier that is inevitably generated to absorb the difference in processing speed of the fixing unit between modes can be used, patch images can be formed and the image forming conditions associated therewith can be corrected. It is. Therefore, according to the first aspect of the present invention, when the fixing process processing speed is lowered than usual, patch image formation and image formation condition correction associated therewith are performed at a high frequency. Since high accuracy such as tone reproducibility can be achieved, as a result, it is possible to realize high quality of the output image.
In the invention according to claim 2, since the image forming means always operates at a constant productivity, it is possible to avoid complicated operation control, thereby simplifying the apparatus configuration. Realization of cost reduction and the like becomes easy.
In the invention according to claim 3, since the patch image is formed in the non-image forming area generated between the image forming areas by widening the image forming pitch, the patch image is formed at the image forming pitch. The image formation is not affected. That is, it can be surely avoided that the formation of the patch image causes a decrease in productivity.
According to the fourth aspect of the invention, the frequency of patch formation can be increased by using the image formation pitch, but a plurality of images of different types (for example, density) are formed as patch images for each image formation pitch. Therefore, an improvement in the accuracy of correcting the image forming condition based on the detection result can be expected.
In the invention according to claim 5, since the frequency of correction of the image forming condition is increased in the case of supporting the low processing speed mode, it is possible to realize a high image quality of the output image in the low processing speed mode. It is suitable for application to a high-quality image output mode.
In the invention according to claim 6, since the medium conveying unit temporarily holds the medium, even if there is a processing speed difference between the image forming unit and the fixing unit, it is possible to reduce the bending of the medium due to the processing speed difference. it can.
In the invention according to claim 7, since the corresponding mode is switched depending on the type of the medium, for example, for a medium having a large basis weight, it is possible to fix the transfer image on the medium in the low processing speed mode. Can be performed reliably and appropriately. That is, for example, it is suitable for dealing with a high-quality image output mode such as a photo print.

The image forming apparatus according to the present invention will be described below.
Here, an electrophotographic image forming apparatus used for a color copying machine, a color printer, or the like will be described as an example.

FIG. 1 is an explanatory diagram schematically showing a schematic configuration example of an image forming apparatus according to the present invention.
The image forming apparatus 1 shown in FIG. 1 is roughly provided with functions as an image forming unit 10, a fixing device 20, a medium conveying unit 30, a condition correcting unit 40, and an operation control unit 50 which are examples of image forming units. ing.

The image forming unit 10 is a function for performing image formation through each process of charging → exposure → development → transfer. For this purpose, the image forming unit 10 includes a photosensitive drum 11 that is rotationally driven, a charger 12 that uniformly charges the surface of the photosensitive drum 11, and an electrostatic latent image on the surface of the photosensitive drum 11. An exposure device 13 for forming, a developing device 14 for developing a latent electrostatic image on the photosensitive drum 11 to form a toner image, and an intermediate transfer belt 15 that is formed in an endless belt and is circulated and driven at the same speed. A primary transfer device 16 that transfers the toner image on the photosensitive drum 11 onto the intermediate transfer belt 15, and a secondary transfer device that transfers the toner image on the intermediate transfer belt 15 onto a medium P such as recording paper. 17 and cleaning devices 18a and 18b for removing foreign matters such as residual toner and paper dust on the photosensitive drum 11 or the intermediate transfer belt 15. In the illustrated example, the developing device 14 is of a rotary type that sequentially performs development of toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K) while rotating. However, a tandem type in which a photosensitive drum and a developing device corresponding to each color are arranged in parallel may be used.
In the image forming unit 10 having such a configuration, the toner image formed on the intermediate transfer belt 15 includes a toner image corresponding to the output image on the medium P, density adjustment, color reproducibility correction, There is a toner patch image used to correct image forming conditions such as gradation correction. Therefore, the image forming unit 10 is provided with an image density detection sensor 19 for detecting the density of the toner patch image. Since the toner patch image itself may be formed and used in the same manner as in the past, detailed description thereof is omitted here.
That is, the image forming unit 10 forms an image (a toner image or a toner patch image corresponding to the output image) on the intermediate transfer belt 15 that is an image holding member, and forms an image on the intermediate transfer belt 15. The transfer of the toner image corresponding to the output image onto the medium P is performed.

  The fixing device 20 is constituted by a fixing device, and executes a fixing process in the electrophotographic system, that is, by heat and pressure with respect to the medium P after the toner image is transferred by the image forming unit 10. This is a function for performing a fixing process and fixing the transferred image on the medium P. However, in the fixing device 20, the transfer image on the medium P is fixed selectively corresponding to one of a plurality of modes having different processing speeds. That is, the fixing device 20 is a medium P having a large basis weight in addition to a normal mode which is an example of a first processing speed mode for fixing a transfer image on the medium P at a standard processing speed. In order to surely fix the transfer image, the low processing speed mode, which is an example of the second processing speed mode in which the transfer image on the medium P is fixed at a speed lower than the standard processing speed, can be supported. It has become. In which mode the fixing process is performed is determined by an instruction from the operation control means 50.

  The medium conveying means 30 is constituted by, for example, a medium conveying conveyor, and delivers the medium P after the image transfer by the image forming unit 10 from the image forming unit 10 to the fixing device 20. Further, the medium transport unit 30 has a function of temporarily waiting the medium P to be delivered.

  The condition correction unit 40 is a function for correcting the image forming condition in the image forming unit 10 based on the detection result by the image density detection sensor 19 for the toner patch image formed on the intermediate transfer belt 15. Examples of the image forming conditions to be corrected include density adjustment, color reproducibility correction, and gradation correction. However, the correction item is not particularly limited. Further, details of the correction method and the like may be performed using a known technique in the same manner as in the prior art, and the description thereof is omitted here.

  The operation control unit 50 is a function for performing operation control on the units 10 to 40 constituting the image forming apparatus 1. For example, an operation speed, an operation timing, or the like is instructed to the image forming unit 10, the fixing device 20, or the medium conveying unit 30, or an operation parameter is instructed to the image forming unit 10 in response to a correction result by the condition correcting unit 40. To go. The instruction for the operation speed here includes an instruction for causing the fixing device 20 to correspond to the low processing speed mode. The operation timing instruction includes an instruction regarding the toner patch image formation timing in the image forming unit 10.

  Among these means 10 to 50, the condition correction means 40 and the operation control means 50 are a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc., which the image forming apparatus 1 has. It is conceivable to realize the function of the computer as a combination by executing a predetermined program. In this case, the predetermined program may be provided by being stored in a computer-readable storage medium prior to installation in the image forming apparatus 1 or distributed via wired or wireless communication means. It may be done.

  Next, a processing operation example in the image forming apparatus 1 configured as described above will be described. However, here, a processing operation example of toner patch image formation in the image forming unit 10 when the fixing device 20 corresponds to the low processing speed mode, which is a characteristic processing operation example in the image forming apparatus 1, will be described in detail. I will explain it.

  In the image forming apparatus 1 having the above-described configuration, for example, when a high-quality image output such as a photographic print is selected on the operation panel (not shown), a predetermined tray (a tray that accommodates a medium having a large basis weight is set). Or when the basis weight of the medium P supplied to the image forming unit 10 is detected by a detection sensor (not shown), and the detection result is larger than a predetermined threshold value. In addition, the operation control unit 50 instructs the fixing device 20 to operate in the low processing speed mode. Thereby, in the image forming apparatus 1, one or more processes including the fixing process by the fixing device 20 are performed in accordance with the low processing speed mode in which processing is performed at a speed lower than the standard processing speed. . This is because when the basis weight of the medium P is large, a large fixing power is required, but due to the performance limit of the fixing device 20, at least the processing speed in the fixing device 20 is reduced to cope with the large fixing power. It is to do. That is, the corresponding mode is switched for the fixing device 20 depending on the type of the medium P, particularly the size of the basis weight.

The criterion for determining whether the basis weight of the medium P is large may be established in advance.
FIG. 2 is an explanatory diagram illustrating a specific example of the basis weight separation criteria. According to the setting in the example, if the basis weight is 80 to 200 gsm, a default process set as a standard processing speed to realize high productivity of image output (increase in the number of outputs per hour). Run each process at speed. On the other hand, when the basis weight is 201 to 300 gsm, a large fixing power is required depending on the size of the basis weight, and such a medium P having a large basis weight is suitable for high-quality image output such as photographic prints. Since it is generally used, emphasis is placed on improving the quality of the output image rather than on high productivity, and one or more processes including the fixing process are performed corresponding to the low processing speed mode.

  Since it is one or more processes including the fixing process, the operation control unit 50 may make each process performed by the image forming unit 10 uniformly correspond to the low processing speed mode, or the fixing process by the fixing device 20. Only the low processing speed mode is allowed to correspond to each process, and the processes performed by the image forming unit 10 may be operated with the same productivity as when dealing with the standard time mode in which the processing speed is higher than the low processing speed mode. . If only the fixing process by the fixing device 20 is made to correspond to the low processing speed mode, the image forming unit 10 may be controlled in the same manner as the standard time even when the low processing speed mode is supported. Regardless of whether the image forming unit 10 is compatible with the low processing speed mode or the standard mode, the image forming unit 10 always operates at a constant productivity.

FIG. 3 is an explanatory diagram showing a specific example of productivity when the standard mode is supported.
When the standard mode is supported, both the image forming unit 10 and the fixing device 20 operate at a higher processing speed than the low processing speed mode (hereinafter, this speed is referred to as “high speed”). Specifically, as shown in FIG. 3A, the image forming unit 10 forms the toner image A and the toner image B for one page of the medium on the circumference of the intermediate transfer belt 15 side by side. In the case where the toner image C and the toner image D are formed side by side on the circumference, the fixing device 20 also uses the toner at a processing speed (high speed) synchronized with the image forming unit 10 as shown in FIG. Fixing processing is sequentially performed on the images A to D.
Even when the standard mode is supported, the toner patch image is formed and the image forming conditions are corrected based on the detection result. In this case, the toner patch image is formed by securing an interval period during which the toner image is not formed on the circumference of the intermediate transfer belt 15 between the toner image formation of a certain page and the toner image formation of the next page. Shall. And the frequency shall be performed by a predetermined period (for example, every 40-50 pages) in order to suppress the productivity fall of image output.

FIG. 4 is an explanatory diagram showing a specific example of productivity when the low processing speed mode is supported. The figure shows an example in which each process performed by the image forming unit 10 is uniformly made to correspond to the low processing speed mode.
In order to make each process uniformly correspond to the low processing speed mode, the image forming unit 10 also needs to change the speed from high speed to low speed. In the changing process, at least one rotation of the intermediate transfer belt 15 is required. A non-image forming period is required. This is in order to avoid the fluctuation of the belt peripheral speed due to the speed change from adversely affecting the image formation. That is, when changing the speed from high speed to low speed, a non-image forming area is generated on the intermediate transfer belt 15 due to the speed difference between the high speed and the low speed.
For this reason, when each process is uniformly adapted to the low processing speed mode, regardless of the formation of the toner patch image of the predetermined cycle described above, the high speed → low speed speed change period is used. A toner patch image is formed in a non-image forming area on the intermediate transfer belt 15 generated due to the speed difference. Then, the toner patch image is detected by the image density detection sensor 19, and the correction of the image forming condition by the condition correcting unit 40 based on the detection result is reflected in the image forming performed by the image forming unit 10 after the speed change. .
In other words, if the operation control unit 50 uniformly corresponds to the low processing speed mode, the operation control unit 50 causes the image forming unit 10 to form a toner patch image due to the processing speed difference between the modes. An instruction is given to the image forming unit 10 so as to be performed in the non-image forming area on the body belt 15.

FIG. 5 is an explanatory diagram showing another specific example of productivity when the low processing speed mode is supported. The figure shows an example in which only the fixing process by the fixing device 20 is made to correspond to the low processing speed mode, and each process performed by the image forming unit 10 is operated with the same productivity as that to the standard mode. .
Even if the fixing device 20 corresponds to the low processing speed mode, if the processing speed in the image forming unit 10 is the same as that in the standard mode, the circumference of the intermediate transfer belt 15 is absorbed in order to absorb the speed difference. The toner image formation interval on the upper side is set larger than that in the standard mode. That is, for example, the toner image A and the toner image B for one page of the medium are formed side by side on the circumference of the intermediate transfer belt 15 in the standard mode, whereas the intermediate transfer belt 15 of the intermediate transfer belt 15 is used in the low processing speed mode. Without changing the peripheral speed, only the toner image A for one page of the medium is formed on the circumference of the intermediate transfer belt 15, and the toner image B is formed on the next circumference. In other words, when dealing with the low processing speed mode, the interval between pages of the formed toner image is lengthened, so that the intermediate transfer belt 15 is non-applied on the intermediate transfer belt 15 due to the processing speed difference between the modes. An image forming area is generated.
For this reason, even when the fixing device 20 is compatible with the low processing speed mode, when the processing speed in the image forming unit 10 is the same as that in the standard mode, the toner patch image having a predetermined cycle is formed. First, a toner patch image is formed in a non-image forming region generated every circumference of the intermediate transfer belt 15 caused by a difference in processing speed between the modes. The toner patch image is detected by the image density detection sensor 19, and the image forming unit 10 corrects the image forming condition by the condition correcting unit 40 based on the detection result on the next circumference of the intermediate transfer belt 15. Reflect in the formation.
In other words, the operation control unit 50 may use the toner patch by the image forming unit 10 if the processing speed in the image forming unit 10 is the same as that in the standard mode even if the fixing device 20 supports the low processing speed mode. An instruction is given to the image forming unit 10 so that an image is formed in a non-image forming area on the intermediate transfer belt 15 caused by a difference in processing speed between modes.
More specifically, the image forming unit 10 increases the toner image formation pitch on the intermediate transfer belt 15 when the fixing device 20 supports the low processing speed mode, thereby achieving the same productivity as when the standard mode is supported. Further, the operation control means 50 causes the toner patch image to be formed in the non-image forming areas formed between the image forming areas by widening the toner image forming pitch.

If the processing speeds of the image forming unit 10 and the fixing device 20 are different, the medium P transported between them may be bent due to the difference in speed. If the medium transport unit 30 that receives the medium P after image transfer from the image forming unit 10 and sends it to the fixing device 20 has a function of temporarily waiting the medium P, the medium in the medium transport unit 30 By the temporary standby of P, the speed difference between the image forming unit 10 and the fixing device 20 is absorbed. Moreover, even if there is a difference in processing speed between them due to the temporary standby, it is possible to avoid occurrence of a jam of the medium P due to the difference in processing speed.
In this embodiment, as a configuration for temporarily waiting, the length of the sheet conveyance path from the secondary transfer device 17 to which the image is transferred to the medium P to the fixing device 20 is larger than the A4 vertical length of 297 mm, which is considered to be the most frequently used. By increasing the length, the bending of the medium due to the difference in processing speed is reduced.

FIG. 6 is an explanatory diagram showing still another specific example of the productivity when the low processing speed mode is supported. The figure also shows an example in which only the fixing process by the fixing device 20 is made to correspond to the low processing speed mode, and each process performed by the image forming unit 10 is operated with the same productivity as that to the standard mode. .
In the example shown in FIG. 5, the non-image forming area on the intermediate transfer belt 15 is different from the example shown in FIG. That is, in the example shown in FIG. 5, the inter-page interval of the formed toner image is lengthened, and as a result, a non-image forming area is generated for each circumference on the intermediate transfer belt 15. In the example, a case in which the periphery for forming the toner image and the non-image forming region are divided not for each circumference on the intermediate transfer belt 15 but for each circumference of the intermediate transfer belt 15 is shown. Even in the case where the non-image forming area is generated in such a manner, the speed between the image forming unit 10 and the fixing device 20 is sufficient if the medium transport unit 30 has a function of temporarily waiting the medium P. While absorbing the difference, only the fixing process by the fixing device 20 is made to correspond to the low processing speed mode, and each process performed by the image forming unit 10 can be operated with the same productivity as that for the standard mode.

  As described above, the image forming apparatus 1 performs one or more processes including the fixing process corresponding to the low processing speed mode when outputting an image to the medium P having a large basis weight. The toner patch image is formed by using a non-image forming area caused by a difference in processing speed between modes, instead of newly securing an area on the intermediate transfer belt 15 for the formation. .

  A plurality of different types of toner patch images may be formed in the non-image forming area. That is, for example, when the standard mode is supported, one toner patch image corresponding to each of the colors Y, M, C, and K is formed, whereas it is formed in the non-image forming area corresponding to the low processing speed mode. In the case of performing, as shown in FIG. 6A, a plurality of images having different densities are formed for each of Y, M, C, and K colors. Specifically, a Y color high density toner patch image and a low density toner patch image, an M color high density toner patch image and a low density toner patch image, a C color high density toner patch image and a low density toner patch image, It is conceivable to form a K color high density toner patch image and a low density toner patch image in the non-image forming area. Here, the density is exemplified as the type of toner patch image, but the toner patch image is not limited to this, and any other type (if any) that can contribute to the improvement of the accuracy of correction of the image forming condition is used. (Saturation etc.) may be different.

  When the low processing speed mode is supported, a toner patch image is formed in the non-image forming area. The frequency of the toner patch image formation and the correction of the image forming conditions associated therewith is low. Higher than standard mode, which is a mode other than. For example, as shown in FIG. 5, when a non-image forming area is generated every circumference on the intermediate transfer belt 15, the toner patch image is always formed and the associated image forming conditions are corrected every circumference. However, at least at a frequency higher than a predetermined cycle (for example, every 40 to 50 pages) when the standard mode is supported, the toner patch image is formed and the image forming conditions associated therewith are corrected. . Note that the frequency when the low processing speed mode is supported and the frequency when the standard mode is supported may be associated with each other or may not be associated at all. As the association, for example, there is a transition from the standard mode to the low processing speed mode in the middle of the predetermined cycle when the standard mode is supported, and the toner patch image is formed using the non-image forming area in the low processing speed mode. If the image forming conditions are corrected, the starting point of the predetermined period when the mode is changed to the standard mode is updated to the processing point in the low processing speed mode instead of the original starting point. Is mentioned.

  In general, when the processing speed of the fixing process is slower than the processing speed of each process in the image forming unit 10, image formation is often performed on the medium P having a large basis weight. The case where the medium P having a large basis weight is used is often a case where high image quality such as a poster print or a photo print is required. Therefore, in the low processing speed mode that is supposed to cope with such a case, a new area on the intermediate transfer body belt 15 is not secured, but the intermediate transfer body is caused by the processing speed difference between the modes. If a toner patch image is formed using a non-image forming area generated on the belt 15, even if the fixing process processing speed is lowered than usual, the patch image is not promoted to reduce productivity. And the correction of the image forming conditions associated therewith are performed at a high frequency, whereby high accuracy such as color reproduction and gradation reproducibility can be achieved. Therefore, the ability to maintain the color reproducibility and gradation reproducibility in the low processing speed mode in a high quality state with high accuracy is enhanced, and as a result, high quality of the output image can be realized.

In the above-described embodiment, the preferred specific example of the present invention has been described. However, the present invention is not limited to the content, and can be appropriately changed without departing from the gist thereof.
For example, the aspects described in the above description, particularly numerical values, are merely specific examples, and the present invention is of course not limited thereto.
Further, in the present embodiment, the case where the two modes, the standard mode and the low processing speed mode, are described as an example, but the corresponding modes may be three or more. Even in this case, a non-image forming area is generated on the intermediate transfer belt 15 due to the difference in processing speed between the modes. Therefore, a toner patch image may be formed in the non-image forming area.
Further, in this embodiment, the image forming unit 10 configured so that the medium P after image transfer passes in the vertical direction and is sent to the fixing device 20 has been described as an example (see FIG. 1). For example, FIG. As shown, it is conceivable that the present invention is applied in exactly the same manner to a configuration in which the medium P is pulled out in the horizontal direction.

1 is an explanatory diagram schematically illustrating a schematic configuration example of an image forming apparatus according to the present invention. It is explanatory drawing which shows a specific example of a basis weight classification | category standard. It is explanatory drawing which shows a specific example of productivity at the time of standard mode response | compatibility of the image forming apparatus which concerns on this invention. FIG. 6 is an explanatory diagram showing a specific example of productivity when the image forming apparatus according to the present invention is compatible with a low processing speed mode. It is explanatory drawing which shows the other specific example of productivity at the time of the low-processing-speed mode response | compatibility of the image forming apparatus which concerns on this invention. It is explanatory drawing which shows the other specific example of productivity at the time of the low-processing-speed mode response | compatibility of the image forming apparatus which concerns on this invention. It is explanatory drawing which shows typically the example of another schematic structure of the image forming apparatus which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming means, 11 ... Photoconductor drum, 12 ... Charger, 13 ... Exposure device, 14 ... Developing device, 15 ... Intermediate transfer belt, 16 ... Primary transfer device, 17 ... Secondary Transfer device, 18a, 18b ... Cleaning device, 19 ... Image density detection sensor, 20 ... Fixing means, 30 ... Medium conveying means, 40 ... Condition correcting means, 50 ... Operation control means

Claims (7)

An image forming means for performing image formation on an image carrier on which the surface circulates and transferring a formed image on the image carrier onto a medium;
Any of a plurality of modes including fixing the image transferred onto the medium and fixing the first processing speed mode and a second processing speed mode having a processing speed slower than the first processing speed mode. Fixing means for selectively responding to the crab,
Condition correcting means for correcting image forming conditions in the image forming means based on the detection result of the patch image formed on the image carrier by the image forming means;
The difference in moving speed of the surface of the image carrier between the second processing speed mode and the first processing speed mode is made smaller than the processing speed difference of the fixing means, and the fixing means In the case of corresponding to the second processing speed mode, the formation of the patch image by the image forming unit is caused by a processing speed difference between the first processing speed mode and the second processing speed mode. An image forming apparatus comprising: an operation control unit configured to use a non-image forming area on the image holding member.   The moving speed of the surface of the image holding member operates at the same speed as when the fixing unit corresponds to the second processing speed mode, even when the fixing unit corresponds to the second processing speed mode. The image forming apparatus according to claim 1. The image forming unit moves the surface of the image carrier between the second processing speed mode and the first processing speed mode when the fixing unit corresponds to the second processing speed mode. The speed difference corresponds to the processing speed difference of the fixing unit and widens the image formation pitch, which is the formation interval between the images formed on the image carrier,
2. The patch control apparatus according to claim 1, wherein the operation control unit causes the non-image forming area formed between the image forming areas to form the patch image by widening the image forming pitch. 2. The image forming apparatus according to 2.   The image forming apparatus according to claim 1, wherein the operation control unit forms a plurality of different types of images for each image forming pitch when forming the patch image at the image forming pitch. apparatus.   When the fixing unit corresponds to the second processing speed mode, the operation control unit determines the frequency of forming the patch image by the image forming unit and the correction of the image forming condition by the condition correcting unit. 5. The image forming apparatus according to claim 1, wherein the image forming apparatus is higher than that in the first processing speed mode. A medium conveying unit that receives the image-transferred medium from the image forming unit and sends the medium to the fixing unit;
The image forming apparatus according to claim 1, wherein the medium conveying unit has a function of temporarily waiting the medium.   The image forming apparatus according to claim 1, wherein the fixing unit switches a corresponding mode according to a type of the medium.

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