JP2021179519A - Image forming apparatus - Google Patents

Abstract

To appropriately prevent a cleaning blade of an intermediate transfer body from being turned up during the execution of a monochrome toner mode.SOLUTION: An image forming apparatus has: control means 500 that, in accordance with a predetermined selection condition, selects a plural toner mode for forming images by using two or more image forming units of a plurality of image forming units, or a single toner mode for forming an image by using one image forming unit of the plurality of image forming units, and controls an image forming operation in accordance with the selected mode; and temperature detection means 142. Even when the control means selects the single toner mode in accordance with the predetermined selection condition, if a temperature condition is satisfied in which a temperature detected by the temperature detection means is higher than a prescribed temperature, the control means selects the plural toner mode.SELECTED DRAWING: Figure 5

Description

The present invention relates to an image forming apparatus.

Conventionally, a plurality of image forming portions that form a toner image on a latent image carrier, an intermediate transfer body that carries a toner image formed on the latent image carrier, and transfer residual toner on the intermediate transfer body are used. A plurality of toner modes for forming an image using a cleaning blade to be cleaned and two or more image forming portions of the plurality of image forming portions according to a predetermined selection condition, or one of the plurality of image forming portions. An image forming apparatus having a single toner mode for forming an image using one image forming unit and a control means for controlling an image forming operation according to the selected mode is known.

For example, in Patent Document 1, in order to increase the image formation speed, when a monochrome image and a color image are mixed and continuously formed, a monochromatic image is usually formed in a single toner mode. However, an image forming apparatus for forming an image in a plurality of toner modes is disclosed.

However, in the conventional image forming apparatus, there is a problem that the cleaning blade for cleaning the transfer residual toner on the intermediate transfer member is rolled up when the single color toner mode is executed.

In order to solve the above-mentioned problems, the present invention comprises a plurality of image forming portions that form a toner image on the latent image carrier, and an intermediate transfer body that carries the toner image formed on the latent image carrier. A plurality of toner modes in which an image is formed by using a cleaning blade for cleaning the transfer residual toner on the intermediate transfer body and two or more image forming portions among the plurality of image forming portions according to predetermined selection conditions, or a plurality of toner modes. An image forming apparatus having a control means for selecting a single toner mode for forming an image using one of the plurality of image forming units and controlling an image forming operation according to the selected mode. , The temperature condition that the temperature detected by the temperature detecting means is higher than the specified temperature even when the single toner mode is selected according to the predetermined selection condition. When the condition is satisfied, the plurality of toner modes are selected.

According to the present invention, it is possible to appropriately suppress the occurrence of a problem that the cleaning blade for cleaning the transfer residual toner on the intermediate transfer member is rolled up when the single color toner mode is executed.

Explanatory drawing which shows the structure of the image forming apparatus of embodiment. Explanatory drawing which shows the state which the surface of the intermediate transfer belt was brought into contact with all the photoconductors by the contact and separation mechanism of the image forming apparatus. Explanatory drawing which shows the state which the photoconductor for color is separated from the surface of the intermediate transfer belt by the contact and separation mechanism of the image forming apparatus. (A) is an explanatory diagram schematically showing the transfer residual toner input to the cleaning blade of the intermediate transfer belt when the image forming operation is performed in the color mode. (B) is an explanatory diagram schematically showing the transfer residual toner input to the cleaning blade of the intermediate transfer belt when the image forming operation is performed in the monochrome mode. The block diagram which shows the main part of the control part which controls the image formation operation in an embodiment. The flowchart which shows the flow of the process which selects the control mode of the image formation operation in an embodiment. The flowchart which shows the flow of the process which selects the control mode of the image formation operation in the modification 1. The flowchart which shows the flow of the process which selects the control mode of the image formation operation in the modification 2.

Hereinafter, an embodiment of the image forming apparatus according to the present invention will be described.
FIG. 1 is an explanatory diagram showing a configuration of an image forming apparatus of the present embodiment.
As shown in FIG. 1, in a substantially central portion inside the main body case 20 of the image forming apparatus 10, a printer engine 74, optical writing that emits an optical beam and irradiates a photosensitive member to be described later with scanning lines by the optical beam. The device 40, the intermediate transfer belt 50 which is an intermediate transfer body, and the like are arranged.

The printer engine 74 includes four process units 30Y, 30C, 30M, and 30K as image forming units that form toner images of different colors from each other. Each process unit 30Y, 30C, 30M, 30K has the same structure. Further, in each process unit 30Y, 30C, 30M, 30K, toner images of different colors are produced by using toners of different colors supplied from the toner bottles 32Y, 32C, 32M, 32K arranged above. It is formed. The toner bottles 32Y, 32C, 32M, and 32K are detachably attached so that they can be replaced with new ones when the toner runs out.

In the following, in the description of this specification and drawings relating to these process units 30Y, 30C, 30M, 30K and the components of the process units 30Y, 30C, 30M, 30K, the subscripts of Y, C, M, and K are used. , Respectively show the colors of yellow, cyan, magenta, and black. In addition, these subscripts are omitted as necessary.

Each process unit 30Y, 30C, 30M, 30K has a photoconductor unit 70Y, 70C, 70M, 70K having photoconductors 60Y, 60C, 60M, 60K rotationally driven in the direction of an arrow, and a developing device 80Y, 80C, 80M, It is composed of 80K. As will be described later, the photoconductor units 70Y, 70C, 70M, 70K have cleaning devices 90Y, 90C, 90M, 90K and charging devices 92Y, 92C, 92M, 92K around the photoconductors 60Y, 60C, 60M, 60K. Has.

The photoconductors 60Y, 60C, 60M, and 60K as the latent image carrier are rotationally driven by a drive motor during printing, and a photosensitive layer is provided on the outer peripheral surface of the cylinder. By irradiating the outer peripheral surface of the photoconductor 60 with a light beam emitted from the optical writing device 40 as a latent image forming means, the outer peripheral surfaces of the photoconductors 60Y, 60C, 60M, and 60K correspond to image data. An electrostatic latent image is written.

The developing apparatus 80Y, 80C, 80M, 80K supplies toner to the photoconductors 60Y, 60C, 60M, 60K. When the supplied toner adheres to the electrostatic latent image written on the outer peripheral surface of the photoconductor 60, the electrostatic latent image on the photoconductor 60 is visualized as a toner image.

The optical writing device 40 irradiates each photoconductor 60Y, 60C, 60M, 60K through a plurality of lens mirrors while polarizing the laser beam L with the polygon mirror 41 based on the image data. As the optical writing device 40, it is also possible to use an LED array (light emitting diode array) method in addition to the polygon scanning method for driving the polygon mirror 41 as described above.

The intermediate transfer belt 50, which is an intermediate transfer body, is a loop-shaped belt formed of a resin film or rubber as a substrate, and a toner image formed on the photoconductor 60 is transferred. The intermediate transfer belt 50 is supported by rollers 100, 110, and 120 and is rotationally driven in the direction of the arrow. On the inner peripheral surface side (inside the loop) of the intermediate transfer belt 50, four primary transfer rollers 130Y, 130C, 130M, 130K for transferring the toner image on each photoconductor 60 onto the intermediate transfer belt 50 are arranged. ing.

The primary transfer nip is formed by sandwiching the intermediate transfer belt 50 between the primary transfer rollers 130Y, 130C, 130M, 130K and the photoconductors 60Y, 60C, 60M, 60K. The primary transfer rollers 130Y, 130C, 130M, 130K are in contact with the inside of the intermediate transfer belt 50. Further, a primary transfer bias is applied to the primary transfer rollers 130Y, 130C, 130M, 130K, and the toner image of the photoconductors 60Y, 60C, 60M, 60K due to the potential difference from the photoconductors 60Y, 60C, 60M, 60K. Is transferred to the surface of the intermediate transfer belt 50. In this way, the toner images formed on the photoconductors 60Y, 60C, 60M, and 60K are sequentially transferred onto the intermediate transfer belt 50, so that the color toner image is supported on the intermediate transfer belt 50. ..

Further, on the outer peripheral surface side (outside of the loop) of the intermediate transfer belt 50, a cleaning unit 140 for cleaning transfer residual toner, paper dust, etc. adhering to the outer peripheral surface of the intermediate transfer belt 50 is arranged. The cleaning unit 140 abuts the tip of the cleaning blade 141 on the outer peripheral surface of the intermediate transfer belt 50 backed up by the cleaning facing roller 115, and removes the transfer residual toner, paper dust, etc. adhering to the outer peripheral surface of the intermediate transfer belt 50. Adopt a blade cleaning method that dams and cleans.

Below the four process units 30Y, 30C, 30M, 30K and the optical writing device 40 in the main body case 20, the first paper feed tray 151 and the second paper feed tray 151, in which the paper P as a recording material is laminated and held. The paper feed tray 152 is arranged. The paper P stacked and held in the first paper feed tray 151 and the second paper feed tray 152 is fed by the paper feed rollers 161 and 162 in order from the highest paper. Further, in the paper feed tray 222 on the right side of the main body case 20, for example, paper P having a size different from that of the first paper feed tray 151 and the second paper feed tray 152 is stored.

In the main body case 20, a transport path 170 is formed in which the paper P separately fed from the first paper feed tray 151 and the second paper feed tray 152 is conveyed. Therefore, the paper P stored in the paper feed trays 151 and 152 and the paper feed tray 222 is taken out from the top-level paper one by one by the rotation drive of the paper feed rollers 160 and 224, and the transport path 170. Will be transported to. A resist roller 180, a secondary transfer roller 190, a fixing device 200, a paper ejection roller 210, and the like are arranged on the transport path 170. A secondary transfer nip is formed between the roller 120 through which the intermediate transfer belt 50 passes and the secondary transfer roller 190. The toner image of each color transferred onto the intermediate transfer belt 50 is transferred to the paper P in the process of the paper P conveyed from the first paper feed tray 151 or the second paper feed tray 152 passing through the secondary transfer nip. Transcribed.

The resist roller 180 is a roller that is intermittently rotationally driven at a predetermined timing. By intermittently rotationally driving the resist roller 180, the paper P that has been conveyed to the position of the resist roller 180 and stopped is sandwiched between the intermediate transfer belt 50 and the secondary transfer roller 190 (secondary transfer position). It is sent to the transfer nip). Then, in the process of the paper P passing through this transfer position, the toner image on the intermediate transfer belt 50 is transferred to the paper P.

The fixing device 200 is a unit that applies heat and pressure to the paper P on which the toner image is transferred to melt the toner and fix the toner image on the paper P. The specific configuration of the fixing device 200 includes a pressurizing roller 201 including a fixing heater 201a (heat generation source) such as a halogen lamp, and a fixing belt unit 202. Further, the fixing belt unit 202 is composed of a fixing belt 204, a heating roller 203 including a fixing heater 203a (heat generation source) such as a halogen lamp, a driving roller 206, and the like. The fixing belt 204 is rotated counterclockwise by the drive roller 206 and heated by the heating roller 203 to maintain a constant temperature. The pressurizing roller 201 also rotates clockwise and is internally heated by a heat generating source to maintain a constant temperature. The fixing belt 204 and the pressure roller 201 are in contact with each other to form a fixing nip.

The paper P is transferred with a toner image supported on the intermediate transfer belt 50 in the process of passing through the intermediate transfer belt 50, and then transferred to a fixing nip in the fixing device 200. The paper P for which the toner image has been fixed by passing through the fixing device 200 is discharged onto the paper ejection tray 220 formed on the upper surface of the main body case 20 by the paper ejection roller 210.

Further, the image forming apparatus 10 of the present embodiment is provided with a contact / detachment mechanism 135 as a contact / detachment means for bringing the color photoconductors 60Y, 60M, 60C into contact with the surface of the intermediate transfer belt 50. There is. The contact / detachment mechanism 135 of the present embodiment is configured to move the primary transfer rollers 130Y, 130C, 130M for color in the vertical direction by a predetermined drive device. The primary transfer roller 130K for black is always in contact with the surface of the intermediate transfer belt 50.

Further, in the present embodiment, as the control mode of the image forming operation, a "color mode" as a plurality of toner modes and a "monochrome mode" as a single toner mode are provided.
The "color mode" is a mode selected when a predetermined selection condition that the image forming target is a color image is satisfied, and as shown in FIG. 2, the contact / separation mechanism 135 covers the entire surface of the intermediate transfer belt 50. This is a mode in which an image is formed by contacting the photoconductors 60Y, 60C, 60M, and 60K. On the other hand, the "monochrome mode" is a mode selected when a predetermined selection condition that the image formation target is a monochrome image is satisfied, and as shown in FIG. 3, the surface of the intermediate transfer belt 50 is provided by the contact / detachment mechanism 135. This is a mode in which an image is formed by separating the color photoconductors 60Y, 60C, and 60M from the above.

Next, a problem in which the cleaning blade 141 for cleaning the intermediate transfer belt 50 is rolled up will be described.
FIG. 4A is an explanatory diagram schematically showing the transfer residual toner input to the cleaning blade 141 of the intermediate transfer belt 50 when the image forming operation is performed in the color mode, and FIG. 4B is an explanatory diagram. It is explanatory drawing which shows typically the transfer residual toner which is input to the cleaning blade 141 of the intermediate transfer belt 50 when the image formation operation is performed in the monochrome mode.

In the present embodiment, when the image forming operation is performed in the color mode, the transfer residual toner TY for the toner images of the four colors formed in the color mode is displayed on the intermediate transfer belt 50 as shown in FIG. 4A. , TC, TM, TB (mainly, ground stain toner adhering to the non-electrostatic latent image portion (ground surface portion) on the photoconductors 60Y, 60C, 60M, 60K) is generated. In this case, since a predetermined amount or more of the transfer residual toner is stably input to the cleaning blade 141 for cleaning the intermediate transfer belt 50, the lubrication function by the transfer residual toner is fully exhibited. Therefore, the blade turning that the cleaning blade 141 is rolled with the surface movement of the intermediate transfer belt 50 does not occur.

On the other hand, in the case of the image forming operation in the monochrome mode, as shown in FIG. 4B, only the transfer residual toner TB for the black toner image formed in the monochrome mode is generated on the intermediate transfer belt 50. Therefore, the amount of residual transfer toner input to the cleaning blade 141 of the intermediate transfer belt 50 is small. In this case, since the amount of residual transfer toner that exerts the lubrication function is small, the blade of the cleaning blade 141 is likely to be rolled up.

In particular, in the present embodiment, since the structure is not provided to apply the lubricant to the outer peripheral surface of the intermediate transfer belt 50, the cleaning blade 141 is likely to be rolled up.

In addition, as in the present embodiment, in the configuration in which the color emitters 60Y, 60M, 60C are separated from the intermediate transfer belt 50 by the contact / detachment mechanism 135 in the monochrome mode, the color photoconductors 60Y, 60M, 60C Even a small amount of ground stain toner that adheres to the top does not adhere to the intermediate transfer belt 50. Therefore, particularly in the case of such a configuration, the amount of transfer residual toner input to the cleaning blade 141 of the intermediate transfer belt 50 is small, and the blade curl of the cleaning blade 141 is likely to occur.

Since it is possible to form an image in the color mode even for a monochrome image formed in the monochrome mode, it is effective to form an image in the color mode for the monochrome image in order to suppress the occurrence of blade turning. However, there is a problem that the toner consumption in the image formation in the color mode is larger than that in the monochrome mode. Therefore, for an image that can be formed in monochrome mode, such as a monochrome image, it is desirable to form the image in monochrome mode as much as possible.

Here, as a result of research on blade curling, the present inventors have found that when the temperature of the cleaning blade 141 rises, blade curling is likely to occur. It is considered that this is because the hardness of the cleaning blade 141 becomes low due to the temperature rise of the cleaning blade 141, and the intermediate transfer belt 50 tends to move around the surface, so that the blade rolls easily.

Therefore, in the present embodiment, a temperature sensor 142 is provided as a temperature detecting means for detecting the temperature inside the main body case 20 (inside the machine) so that the temperature of the cleaning blade 141 can be grasped. In the present embodiment, the temperature of the cleaning blade 141 is grasped by using the temperature detection result of the temperature sensor 142 installed near the secondary transfer unit, but a correlation with the temperature of the cleaning blade 141 is recognized. As long as it is a temperature sensor that detects the temperature of a certain place, a temperature sensor of another place may be used.

Then, in the present embodiment, even when a monochrome image is formed, if the detection temperature of the temperature sensor 142 is higher than the specified temperature, the color mode is selected and the image forming operation is executed. As a result, the amount of transfer residual toner input to the cleaning blade 141 increases as compared with the monochrome mode, and the occurrence of blade curling is suppressed. On the other hand, if the temperature detected by the temperature sensor 142 is a temperature equal to or lower than the specified temperature at which blade turning is unlikely to occur, the monochrome mode is selected as it is and the image forming operation of the monochrome image is executed. In this case, it is possible to form a monochrome image while suppressing the toner consumption as compared with the case of selecting the color mode in a state where the occurrence of blade curling is suppressed.

FIG. 5 is a block diagram showing a main part of the control unit 500 that controls the image forming operation in the present embodiment.
FIG. 6 is a flowchart showing a flow of processing for selecting a control mode for an image forming operation in the present embodiment.
When a print job is input to the control unit 500 of the image forming apparatus 10 (S1), the mode selection unit 501 of the control unit 500 determines whether or not the image related to the input print job is a monochrome image (S1). S2). In this determination, when it is determined that the image is not a monochrome image (for example, when it is determined that the image is a color image), the mode selection unit 501 selects the color mode (S3). As a result, the image formation control unit 502 controls the contact / detachment mechanism 135 as necessary to bring the surface of the intermediate transfer belt 50 into contact with all the photoconductors 60Y, 60C, 60M, 60K as shown in FIG. Then, an image forming operation for forming an image (color image) according to the print job is executed (S6).

On the other hand, when it is determined that the image is a monochrome image, the mode selection unit 501 next acquires the detected temperature from the temperature sensor 142, and determines whether or not the detected temperature is equal to or higher than the specified temperature Tth (S4). In this determination, when it is determined that the detected temperature is less than the specified temperature Tth (No in S4), the mode selection unit 501 selects the monochrome mode (S5), and the image formation control unit 502 determines, if necessary. As shown in FIG. 3, the contact / detachment mechanism 135 is controlled to separate the color photoconductors 60Y, 60C, and 60M from the surface of the intermediate transfer belt 50 to form an image forming operation for forming a monochrome image according to a print job. Execute (S6).

On the other hand, even when it is determined that the image is a monochrome image, if it is determined that the detected temperature of the temperature sensor 142 is equal to or higher than the specified temperature Tth (Yes in S4), the mode selection unit 501 selects the color mode (S3). ). As a result, the image formation control unit 502 controls the contact / detachment mechanism 135 as necessary to separate the color photoconductors 60Y, 60C, and 60M from the surface of the intermediate transfer belt 50 as shown in FIG. , An image forming operation for forming a monochrome image according to a print job is executed (S6).

As described above, according to the present embodiment, even when a monochrome image is formed, when the temperature condition that the detection temperature of the temperature sensor 142 is higher than the specified temperature is satisfied, the color mode is selected and the image forming operation is performed. To execute. That is, when the temperature condition at which blade turning is likely to occur is satisfied, the color mode is selected instead of the monochrome mode and the image forming operation is executed. As a result, the amount of transfer residual toner input to the cleaning blade 141 increases as compared with the monochrome mode, and the occurrence of blade curling is suppressed. On the other hand, if the temperature detected by the temperature sensor 142 is a temperature equal to or lower than the specified temperature at which blade turning is unlikely to occur, the monochrome mode is selected as it is and the image forming operation of the monochrome image is executed. In this case, it is possible to form a monochrome image while suppressing the toner consumption as compared with the case of selecting the color mode in a state where the occurrence of blade curling is suppressed.

[Modification 1]
Next, a modification of the above-described embodiment (hereinafter, referred to as “modification 1”) will be described.
Generally, when the continuous image forming operation is executed, the cleaning blade 141 is continuously loaded from the intermediate transfer belt 50, so that the blade curl tends to occur as the number of images formed in the continuous image forming operation increases. However, conversely, even when the continuous image forming operation is executed, when the number of image forming sheets is small, even if the in-machine temperature is equal to or higher than the specified temperature Tth, the blade turning is unlikely to occur. Therefore, in the present modification 1, the color mode is selected when the condition of the number of image formations that the number of continuous images formed in the monochrome mode is larger than the specified number is also satisfied.

FIG. 7 is a flowchart showing the flow of the process of selecting the control mode of the image forming operation in the present modification 1.
In the present modification 1, it is determined that the input print job is a monochrome image (Yes in S1 and S2), and the detected temperature of the temperature sensor 142 is determined to be equal to or higher than the specified temperature Tth (Yes in S4). , The mode selection unit 501 determines whether or not the number of prints (the number of continuous images formed) of the print job is equal to or more than the specified number (S11).

In this determination, when it is determined that the number of prints is less than the specified number (No in S11), the mode selection unit 501 is considered to be in a situation where the blade curl is unlikely to occur even if the internal temperature is equal to or higher than the specified temperature Tth. Select the monochrome mode (S5). On the other hand, when it is determined that the number of prints is equal to or greater than the specified number (Yes in S11), the mode selection unit 501 selects the color mode (S3), assuming that the blade curl is likely to occur.

As described above, according to the present modification 1, when a monochrome image is formed, even when the temperature condition that the detection temperature of the temperature sensor 142 is higher than the specified temperature is satisfied, the number of continuous images formed is the occurrence of blade curling. When the number is difficult to measure (less than the specified number), the monochrome mode is selected and the image forming operation is executed. As a result, it is possible to increase the number of cases in which a monochrome image can be formed while suppressing the toner consumption as compared with the case of selecting the color mode in the state where the occurrence of blade curling is suppressed.

In the present modification 1, when it is determined that the number of prints is equal to or more than the specified number, the color mode is selected before the print job is executed, and the entire image forming operation of the print job is executed in the color mode. As an example, the monochrome mode may be switched to the color mode in the middle of the print job (in the middle of the continuous image formation period), that is, when the number of prints reaches the specified number. In this case, even if the number of prints of the print job is more than the specified number, the monochrome mode is selected until the number of continuous image formations reaches a small number (less than the specified number) at which blade turning is unlikely to occur, and the toner consumption is suppressed. can do. However, in this case, since the operation for mode switching (operation of the contact / detachment mechanism 135, etc.) is performed in the middle of the print job, the productivity of the image of the print job is lowered. Therefore, when giving priority to image productivity, it is preferable to select the color mode before executing the print job when it is determined that the number of prints is equal to or more than the specified number as in the first modification.

[Modification 2]
Next, another modification of the above-described embodiment (hereinafter, referred to as “modification 2”) will be described.
In general, even in a monochrome image, the higher the image area ratio, the larger the transfer residual toner tends to be. Therefore, when forming a monochrome image having a high image area ratio, blade turning is unlikely to occur even if the in-machine temperature is equal to or higher than the specified temperature Tth. Therefore, in the second modification, the color mode is selected when the image area ratio condition that the image area ratio of the image (monochrome image) formed in the monochrome mode is equal to or less than the specified threshold value is also satisfied.

FIG. 8 is a flowchart showing the flow of the process of selecting the control mode of the image forming operation in the second modification.
In the second modification, it is determined that the input print job is a monochrome image (Yes in S1 and S2), and the detected temperature of the temperature sensor 142 is determined to be equal to or higher than the specified temperature Tth (Yes in S4). , The mode selection unit 501 determines whether or not the image area ratio of the monochrome image is equal to or less than the specified threshold value (S12).

In this determination, when it is determined that the image area ratio is larger than the specified threshold value (No in S12), it is considered that the blade turning is unlikely to occur even if the in-machine temperature is equal to or higher than the specified temperature Tth, and the mode selection unit 501 Selects a monochrome mode (S5). On the other hand, when it is determined that the image area ratio is equal to or less than the specified threshold value (Yes in S12), the mode selection unit 501 selects the color mode (S3), assuming that the blade turning is likely to occur.

As described above, according to the present modification 2, when a monochrome image is formed, the image area ratio causes blade curling even when the temperature condition that the detection temperature of the temperature sensor 142 is higher than the specified temperature is satisfied. When it is larger than the difficult specified threshold, the monochrome mode is selected and the image forming operation is executed. As a result, it is possible to increase the number of cases in which a monochrome image can be formed while suppressing the toner consumption as compared with the case of selecting the color mode in the state where the occurrence of blade curling is suppressed.

In the second modification, it may be determined for each image whether or not the image area ratio of the monochrome image is equal to or less than the specified threshold value. In this case, printing in which a plurality of image forming operations are continuously performed is performed. An operation for mode switching (operation of the contact / detachment mechanism 135, etc.) may be performed in the middle of the job, which may reduce the productivity of the image of the print job. Therefore, when giving priority to image productivity, it is possible to determine whether or not the image area ratio is equal to or less than the specified threshold before executing the print job, and select the mode according to the image area ratio. good. As the image area ratio at this time, for example, it is preferable to use the average image area ratio for a plurality of images related to all or part of the print job.

In this embodiment (including each of the above-described modifications), it is determined that the input print job is a monochrome image (Yes in S1 and S2), and the detection temperature of the temperature sensor 142 is equal to or higher than the specified temperature Tth. When it is determined that there is (Yes in S4), the image formation operation is controlled so that the transfer residual toner on the intermediate transfer belt 50 increases as compared with the normal color mode (when the color image is formed in the color mode). You may. As a specific example, for example, it is possible to increase the amount of ground stain toner by lowering the skin potential by lowering the photoconductor charging potential (ground surface potential) by the charging devices 92Y, 92C, 92M, 92K. In this case, more toner can be input to the cleaning blade 141, and blade curling can be suppressed more stably.

The above description is an example, and the effect peculiar to each of the following aspects is exhibited.
[First aspect]
The first aspect is a plurality of image forming units (for example, process units 30Y, 30C, 30M, 30K) that form a toner image on a latent image carrier (for example, photoconductors 60Y, 60C, 60M, 60K), and the latent image. An intermediate transfer body (for example, an intermediate transfer belt 50) that carries a toner image formed on the carrier, a cleaning blade 141 that cleans the transfer residual toner on the intermediate transfer body, and a plurality of the above according to predetermined selection conditions. A plurality of toner modes (for example, a color mode) for forming an image using two or more image forming portions (process units 30Y, 30C, 30M, 30K) of the image forming portions, or among the plurality of image forming portions. A control means (for example, control unit 500) that selects a single toner mode (for example, monochrome mode) for forming an image using one image forming unit (process unit 30K for black) and controls an image forming operation according to the selected mode. The image forming apparatus 10 has a temperature detecting means (for example, a temperature sensor 142), and the control means selects the single toner mode according to the predetermined selection condition. It is characterized in that the plurality of toner modes are selected when the temperature condition that the temperature detected by the temperature detecting means is higher than the specified temperature Tth is satisfied.
In the case of the image forming operation in the plurality of toner modes, the transfer residual toner for the plurality of toner images formed in the plurality of toner modes is generated on the intermediate transfer body, so that the cleaning blade for cleaning the intermediate transfer body is used. , A transfer residual toner of a predetermined amount or more is stably input. In this case, since the lubrication function by the transfer residual toner is fully exerted, the blade curl that the cleaning blade is curled with the surface movement of the intermediate transfer body does not occur.
On the other hand, in the case of the image forming operation in the single toner mode, only the transfer residual toner for the single toner image formed in the single toner mode is generated on the intermediate transfer body. In this case, since the amount of transfer residual toner input to the cleaning blade of the intermediate transfer body is small, the lubrication function by the transfer residual toner becomes insufficient, and the blade of the cleaning blade is likely to be rolled up.
In order to suppress the occurrence of blade turning, it is effective to form an image in the multiple toner modes even for an image that can form an image in the single toner mode, but in this case, the toner consumption is higher than in the single toner mode. There is a problem that it increases. Therefore, for an image that can form an image in the single toner mode, it is desirable to form the image in the single toner mode as much as possible.
As a result of the research, the present inventors have found that, as described above, the blade curl is likely to occur when the temperature of the cleaning blade rises. It is considered that this is because the hardness of the cleaning blade becomes low due to the temperature rise of the cleaning blade, and it becomes easy to move around the surface of the intermediate transfer body and the blade rolls easily.
Therefore, in this embodiment, even when the single toner mode is selected according to a predetermined selection condition, the plurality of toner modes are selected when the temperature condition that the temperature detected by the temperature detecting means is higher than the specified temperature is satisfied. Then, the image forming operation is executed. As a result, when the temperature condition at which blade curling is likely to occur is satisfied, a plurality of toner modes are selected instead of the single toner mode and the image forming operation is executed. As a result, the amount of transfer residual toner input to the cleaning blade increases as compared with the single toner mode, and the occurrence of blade curling is suppressed. On the other hand, if the temperature detected by the temperature detecting means is a temperature equal to or lower than the specified temperature at which blade rolling is unlikely to occur, the single toner mode is selected as it is and the image forming operation is executed. In this case, the toner consumption can be suppressed as compared with the case of selecting the plurality of toner modes.
Therefore, it is possible to appropriately suppress the occurrence of a problem that the cleaning blade for cleaning the transfer residual toner on the intermediate transfer body is rolled up when the single color toner mode is executed.

[Second aspect]
In the second aspect, in the first aspect, the plurality of image forming portions are black image forming portions (for example, for black) that form a black toner image on a black latent image carrier (for example, black photoconductor 60K). (Process unit 30K) and a plurality of color image forming units (for example, color process units 30Y, 30C) that form a color toner image on a color latent image carrier (for example, color photoconductors 60Y, 60C, 60M). , 30M), the single toner mode is a monochrome mode in which a monochrome image is formed by using the black image forming unit without using the plurality of color image forming units, and the plurality of toner modes are The color mode is characterized in that a color image is formed by using the plurality of color image forming units.
According to this, it is possible to appropriately suppress the occurrence of a problem that the cleaning blade for cleaning the transfer residual toner on the intermediate transfer member is rolled up when the monochrome mode, which is widely used, is executed.

[Third aspect]
The third aspect is the latent image of the image forming part (for example, process units 30Y, 30C, 30M for color) which is not used in the single toner mode among the plurality of image forming parts in the first or second aspect. It has a contact / detachment means (for example, a contact / detachment mechanism 135) for bringing a carrier (for example, color photosensitive members 60Y, 60C, 60M) into contact with the intermediate transfer body, and in the single toner mode, the single toner is provided. An image is formed in a state where the latent image carrier of the image forming portion, which is not used in the mode, is separated from the intermediate transfer body by the contacting / detaching means, and the image is not used in the single toner mode in the plurality of toner modes. It is characterized in that an image is formed in a state where the latent image carrier of the forming portion is brought into contact with the intermediate transfer body by the contacting / detaching means.
In the image forming apparatus provided with such contacting and detaching means, even the ground-staining toner slightly adhering to the latent image carrier of the image forming portion, which is not used in the single toner mode, does not adhere to the intermediate transfer body. .. Therefore, the amount of residual transfer toner input to the cleaning blade of the intermediate transfer body in the single toner mode is further smaller than that of the image forming apparatus not provided with such contact / detachment means, and the blade of the cleaning blade is likely to be rolled up.
According to this aspect, in such an image forming apparatus in which blade curling is likely to occur, blade curling can be appropriately suppressed.

[Fourth aspect]
In the fourth aspect, in any one of the first to third aspects, the control means not only satisfies the temperature condition, but also defines the number of image formations (for example, the number of prints) for continuously forming an image in the single toner mode. It is characterized in that the plurality of toner modes are selected when the condition of the number of image formations to be larger than the number is also satisfied.
According to this aspect, even when the temperature condition is satisfied, when the number of continuous images formed in the single toner mode is a small number (less than the specified number) in which blade turning is unlikely to occur, the single toner mode is selected for the image. The forming operation is performed. As a result, it is possible to increase the number of cases in which the image forming operation is executed while suppressing the toner consumption as compared with the case of selecting the plurality of toner modes in the state where the occurrence of blade curling is suppressed.

[Fifth aspect]
In a fifth aspect, in any one of the first to fourth aspects, the control means not only satisfies the temperature condition, but also has an image area ratio of an image formed in the single toner mode of a specified threshold value or less. It is characterized in that the plurality of toner modes are selected when the image area ratio condition is also satisfied.
According to this aspect, even when the temperature condition is satisfied, when the image area ratio is larger than the specified threshold value at which blade turning is unlikely to occur, the single toner mode is selected and the image forming operation is executed. As a result, it is possible to increase the number of cases in which the image forming operation is executed while suppressing the toner consumption as compared with the case of selecting the plurality of toner modes in the state where the occurrence of blade curling is suppressed.

[Sixth aspect]
A sixth aspect is, in any one of the first to fifth aspects, when the control means satisfies the temperature condition and selects the plurality of toner modes, the control means selects the plurality of toner modes without satisfying the temperature condition. It is characterized in that the image forming operation is controlled so that the transfer residual toner on the intermediate transfer body increases more than the case.
According to this, more transfer residual toner can be input to the cleaning blade, and blade curling can be suppressed more stably.

[7th aspect]
A seventh aspect is, in any one of the first to sixth aspects, when the control means satisfies the condition for selecting the plurality of toner modes during the continuous image formation period by the single toner mode, the continuous image. During the image forming period, the mode to be selected is switched from the single toner mode to the plurality of toner modes to control the image forming operation.
According to this, it is possible to suppress the toner consumption as compared with the case where the image forming operation is performed by selecting the plurality of toner modes from the beginning of the continuous image forming period.

10: Image forming device 20: Main body case 30: Process unit 40: Optical writing device 50: Intermediate transfer belt 60: Photoreceptor 70: Photoconductor unit 74: Printer engine 80: Developing device 90: Cleaning device 92: Charging device 100 , 110, 120: Roller 130: Primary transfer roller 135: Contact / detachment mechanism 140: Cleaning unit 141: Cleaning blade 142: Temperature sensor 170: Conveyance path 180: Resist roller 190: Secondary transfer roller 200: Fixing device 210: Paper ejection Roller 220: Paper ejection tray 500: Control unit 501: Mode selection unit 502: Image formation control unit

Japanese Unexamined Patent Publication No. 2007-11151

Claims (7)

A plurality of image forming portions that form a toner image on a latent image carrier,
An intermediate transfer member that carries a toner image formed on the latent image carrier, and an intermediate transfer member that carries the toner image.
A cleaning blade for cleaning the transfer residual toner on the intermediate transfer body, and
A plurality of toner modes for forming an image using two or more image forming portions of the plurality of image forming portions, or one of the image forming portions of the plurality of image forming portions is used according to a predetermined selection condition. An image forming apparatus having a control means for selecting a single toner mode for forming an image and controlling an image forming operation according to the selected mode.
Has a temperature detecting means,
Even when the single toner mode is selected according to the predetermined selection condition, the control means satisfies the temperature condition that the temperature detected by the temperature detecting means is higher than the specified temperature, the plurality of toner modes. An image forming apparatus characterized by selecting. In the image forming apparatus according to claim 1,
The plurality of image forming portions include a black image forming portion that forms a black toner image on a black latent image carrier, and a plurality of color images that form a color toner image on the color latent image carrier. Including the forming part
The single toner mode is a monochrome mode in which a monochrome image is formed by using the black image forming unit without using the plurality of color image forming units.
The plurality of toner modes are image forming apparatus characterized in that they are color modes for forming a color image by using the plurality of color image forming units. In the image forming apparatus according to claim 1 or 2.
It has a contacting / detaching means for bringing the latent image carrier of the image forming portion, which is not used in the single toner mode among the plurality of image forming portions, into contact with the intermediate transfer body.
In the single toner mode, an image is formed in a state where the latent image carrier of the image forming portion, which is not used in the single toner mode, is separated from the intermediate transfer body by the contacting and detaching means.
The plurality of toner modes is characterized in that an image is formed in a state where the latent image carrier of the image forming portion, which is not used in the single toner mode, is brought into contact with the intermediate transfer body by the contacting and detaching means. Device. The image forming apparatus according to any one of claims 1 to 3.
The control means selects the plurality of toner modes when not only the temperature condition is satisfied but also the image formation number condition that the number of image formations for continuous image formation in the single toner mode is larger than the specified number. An image forming apparatus characterized in that. The image forming apparatus according to any one of claims 1 to 4.
The control means selects the plurality of toner modes when not only the temperature condition is satisfied but also the image area ratio condition that the image area ratio of the image formed in the single toner mode is equal to or less than the specified threshold value is satisfied. An image forming apparatus characterized by The image forming apparatus according to any one of claims 1 to 5.
When the control means satisfies the temperature condition and selects the plurality of toner modes, the transfer residual toner on the intermediate transfer body increases as compared with the case where the plurality of toner modes are selected without satisfying the temperature condition. In addition, an image forming apparatus characterized by controlling an image forming operation. The image forming apparatus according to any one of claims 1 to 6.
When the condition for selecting the plurality of toner modes is satisfied during the continuous image forming period by the single toner mode, the control means sets the mode to be selected during the continuous image forming period. An image forming apparatus characterized in that the image forming operation is controlled by switching from the above to the plurality of toner modes.

Images