JP2021071618A - Image forming apparatus - Google Patents

Abstract

To avoid a reduction in productivity of printing as much as possible while appropriately reducing thermal deterioration of developer to thereby improve convenience.SOLUTION: An image forming apparatus 10 comprises: a developing device 22; a temperature detection unit 43; and a control unit 46. When the temperature detected by the temperature detection unit 43 is less than a predetermined threshold temperature, the control unit 46 operates the developing unit 22 in a normal printing mode, and when the temperature detected by the temperature detection unit 43 is equal to or higher than the threshold temperature, if a drive time ratio of the drive time of the developing device 22 in a period immediately before the time point at which the temperature becomes equal to or higher than the threshold temperature is less than a first threshold time ratio, does not set a cooling mode and maintains the normal printing mode, and if the drive time ratio is equal to or more than the first threshold time ratio, sets the cooling mode and restricts the operation of the developing device 22.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image forming apparatus including a developing apparatus, and more particularly to cooling control of the developing apparatus.

In the developing apparatus of the image forming apparatus, the developing agent is conveyed while stirring, and the developing agent is applied to the electrostatic latent image of the image carrier via the developing roller to visualize the electrostatic latent image of the image carrier. It is being developed into an image (image of a developer). For example, in an image forming apparatus, when the temperature of the developing apparatus carrying and transporting the developing agent rises due to continuous printing or the like, the printing operation is restricted or interrupted in order to prevent thermal deterioration of the developing agent. Cooling is done.

For example, the image forming apparatus described in Patent Document 1 detects the temperature around the developing apparatus, sets the number of image forming times per unit time corresponding to the detected temperature around the developing apparatus, and develops by continuous printing or the like. When the temperature of the developing apparatus that carries and conveys the agent rises, the printing operation is restricted or interrupted in order to prevent the thermal deterioration of the developing agent, so that the thermal deterioration of the developing agent is prevented.

Japanese Unexamined Patent Publication No. 2003-122192

Since it is difficult to directly monitor the actual temperature of the developing agent, the image forming apparatus described in Patent Document 1 detects the ambient temperature of the developing apparatus and predicts based on the detected ambient temperature of the developing apparatus. Printing is restricted / interrupted. Therefore, at the actual temperature of the developer, there is a problem that the convenience is hindered because the printing is restricted even when the printing restriction is not yet required.

In addition, while the number of cases of use in a high temperature environment is increasing due to the influence of global warming in recent years, the melt viscosity of the developer is becoming lower in order to comply with environmental regulations. For this reason, it is expected that there will be an increasing number of cases where printing is restricted / interrupted and convenience is impaired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve convenience by appropriately reducing thermal deterioration of a developing agent and avoiding a decrease in printing productivity as much as possible.

The image forming apparatus according to one aspect of the present invention is an image forming apparatus including a developing apparatus, and the developing apparatus applies a developer to an electrostatic latent image formed on an image carrier to apply the developer to the electrostatic. A developing roller that develops a latent image into a visible image, a developing agent accommodating portion that has a stirring member that stirs the developing agent while being conveyed along the developing roller, and supplies the developing agent to the developing roller. Further, the image forming apparatus further performs continuous printing based on a temperature detecting unit that detects the temperature of the developing agent accommodating unit and a temperature detected by the temperature detecting unit when a printing request is received. A control unit that sets a possible normal print mode or a cooling mode that cools the developing device by limiting the operation of the developing device to execute printing related to the printing request, and the control unit includes the control unit. When the temperature detected by the temperature detection unit is less than a predetermined threshold temperature, the developing apparatus is operated in the normal printing mode, and the temperature detected by the temperature detection unit is equal to or higher than the threshold temperature. If the drive time ratio indicating the ratio of the drive time of the developing apparatus in the period immediately before the time when the temperature exceeds the threshold temperature is less than the predetermined first threshold time ratio, the normal printing is performed without setting the cooling mode. When the mode is maintained and the drive time ratio is equal to or greater than the first threshold time ratio, the cooling mode is set to limit the operation of the developing apparatus.

Further, the image forming apparatus according to another aspect of the present invention is an image forming apparatus including a developing apparatus, and the developing apparatus applies a developer to an electrostatic latent image formed on an image carrier. A developer that has a developing roller that develops the electrostatic latent image into a visible image, and a stirring member that stirs the developer while transporting it along the developing roller, and supplies the developer to the developing roller. The image forming apparatus further includes a temperature detecting unit for detecting the temperature of the developing agent accommodating unit, and a temperature detecting unit based on the temperature detected by the temperature detecting unit when a printing request is received. The control unit includes a normal print mode capable of continuous printing or a control unit which sets a cooling mode for cooling the developing device by limiting the operation of the developing device and executes printing related to the printing request. When the temperature detected by the temperature detection unit is less than a predetermined threshold temperature, the unit operates the developing apparatus in the normal printing mode, and the control unit measures the temperature detected by the temperature detection unit. When the temperature is equal to or higher than the threshold temperature, a predetermined second driving time ratio in the period immediately preceding the time when the temperature reaches the threshold temperature or higher is equal to or higher than the first threshold time ratio and larger than the first threshold time ratio. If it is less than the threshold time ratio, the first cooling mode is set as the cooling mode, and the driving time ratio in the period immediately before the time when the temperature becomes equal to or higher than the threshold temperature is equal to or higher than the second threshold time ratio and the second. If it is larger than the threshold time ratio and less than a predetermined third threshold time ratio, the cooling mode is set to the second cooling mode in which the operation is restricted compared to the first cooling mode, and the temperature becomes equal to or higher than the threshold temperature. If the drive time ratio in the period immediately preceding the time point is equal to or greater than the third threshold time ratio, the cooling mode is set to the third cooling mode in which the operation of the developing apparatus is stopped.

According to the present invention, it is possible to improve convenience by appropriately reducing thermal deterioration of the developer while avoiding a decrease in printing productivity as much as possible.

It is sectional drawing which shows the image formation apparatus of 1st Embodiment of this invention. It is a vertical cross-sectional view which shows the photoconductor drum, the developing apparatus and the like in the image forming apparatus of this embodiment. It is sectional drawing which shows the developer accommodating part of a developing apparatus. It is a functional block diagram which shows the main internal structure of an image forming apparatus. It is a functional block diagram which shows the main internal structure and the like of the drive part shown in FIG. It is a figure which shows the determination table of 1st Embodiment. (A) is a diagram for explaining the mode setting when the detection temperature becomes the threshold temperature or higher, and (B) explains the mode setting at the mode determination timing after the time when the detection temperature becomes the threshold temperature or higher. It is a figure for doing. It is a flowchart which shows the cooling control of the developing apparatus in the image forming apparatus of 1st Embodiment. It is a figure which shows an example of the divergence between a toner temperature and an ambient temperature of a developing apparatus. It is a flowchart which shows the cooling control in the image forming apparatus of 2nd Embodiment. It is a figure which shows the determination table of the 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an image forming apparatus according to the first embodiment of the present invention. The image forming apparatus 10 includes an image reading unit 11 and an image forming unit 12.

The image reading unit 11 has an image sensor that optically reads an image of the manuscript paper, and the analog output of the image sensor is converted into a digital signal to generate image data indicating the image of the manuscript paper.

The image forming unit 12 prints the image indicated by the image data on the recording paper, and has an image forming unit 3M for magenta, an image forming unit 3C for cyan, an image forming unit 3Y for yellow, and black. The image forming unit 3Bk of the above is provided. In each of the image forming units 3M, 3C, 3Y, and 3Bk, the surface of the photoconductor drum 4 is uniformly charged, the surface of the photoconductor drum 4 is exposed, and an electrostatic latent image is formed on the surface of the photoconductor drum 4. Is formed, the electrostatic latent image on the surface of the photoconductor drum 4 is developed into a visible image (image of a developer), and the visible image on the surface of the photoconductor drum 4 is transferred to the intermediate transfer belt 5. As a result, a visible image of color is formed on the intermediate transfer belt 5. This color visible image is secondarily transferred to the recording paper P conveyed from the paper feed unit 14 through the transfer path 8 in the nip area N between the intermediate transfer belt 5 and the secondary transfer roller 7. The photoconductor drum 4 is an example of an image carrier within the scope of claims.

After that, the recording paper P is heated and pressurized by the fixing device 15, the visible image on the recording paper P is fixed by thermocompression bonding, and the recording paper P is further discharged to the discharge tray 17 through the discharge roller 16.

FIG. 2 is a vertical cross-sectional view showing a set of photoconductor drums 4 and a developing device 22 in each image forming unit 3M, 3C, 3Y, and 3Bk. Further, FIG. 3 is a cross-sectional view showing a developer accommodating portion 31 of the developing apparatus 22.

As shown in FIG. 2, a photoconductor drum 4, a developing device 22, a primary transfer roller 6, and the like are provided for each of the image forming units 3M, 3C, 3Y, and 3Bk. Around the photoconductor drum 4, a static eliminator 24 that eliminates static electricity on the surface of the photoconductor drum 4, a cleaning unit 25 that cleans the toner remaining on the surface of the photoconductor drum 4, and the surface of the photoconductor drum 4 are uniformly charged. The charged portion 26, the exposed portion 23 that forms an electrostatic latent image on the surface of the photoconductor drum 4, and the like are provided. The developing apparatus 22 is provided with a developing roller 27, a layer regulating member 28, a developing agent accommodating portion 31 accommodating a developing agent, two spiral feeders 32 for circulating and conveying the developing agent, and the like. The spiral feeder 32 is an example of a stirring member within the scope of claims.

In this embodiment, a one-component magnetic toner is used as the developing agent contained in the developing agent accommodating portion 31 of the developing apparatus 22. The developing roller 27 includes a sleeve made of a metal such as aluminum, a magnet provided inside the sleeve and having a developing electrode, a layer regulating electrode, and the like. Further, the surface of the sleeve of the developing roller 27 is formed with irregularities having a predetermined roughness for stabilizing the transfer of the developing agent.

The layer regulating member 28 regulates the layer thickness of the developer on the surface of the developing roller 27. Specifically, the layer regulating member 28 is composed of a magnetic blade and a magnet, generates a magnetic field between the layer regulating electrode of the magnet in the developing roller 27, and the developing roller is formed by a gap between the developing roller 27 and the sleeve. A thin layer of developer is formed on the surface of 27.

As shown in FIGS. 2 and 3, the developer accommodating portion 31 has two supply transport paths 31A and a reflux transport path 31B arranged side by side with respect to the developing roller 27 and partitioned by a partition wall 29. The supply transport path 31A and the reflux transport path 31B are connected through the connecting paths 31C and 31D at both ends to form a circulation transport path through which the developer circulates. Spiral feeders 32 are provided in the supply transport path 31A and the reflux transport path 31B, respectively. Each spiral feeder 32 is rotationally driven in the direction of the arrow by a drive unit 47 shown in FIG. 4, which will be described later.

In the supply transport path 31A, the developer is subjected to the spiral feeder 32 of the supply transport path 31A from the upstream side in the transport direction of the developer to the downstream side in the transport direction (from one end side to the other end side of the developing roller 27) in the arrow direction. It is agitated while being transported to the developing roller 27, supplied to the developing roller 27, and sent out to the reflux transport path 31B through one of the connecting paths 31C. Further, in the reflux transfer path 31B, the developer is agitated while being conveyed by the spiral feeder 32 of the reflux transfer path 31B in the direction opposite to the transfer direction in the supply transfer path 31A, and is agitated while being conveyed in the direction opposite to the transfer direction in the supply transfer path 31A. Returned to 31A. As a result, the developer is supplied to the developing roller 27 while being circulated and conveyed.

The developer accommodating unit 31 is provided with a developer replenishment port (not shown), and the amount of the developer contained in the developer accommodating unit 31 is maintained by replenishing the developer through the replenishment port. Will be done.

The developing roller 27 and the photoconductor drum 4 are rotationally driven in the direction of the arrow by the driving unit 47 shown in FIG. 4, which will be described later. A developer is supplied to the sleeve surface of the developing roller 27, a thin layer of the developer is formed on the sleeve surface of the developing roller 27 by the layer regulating member 28, and the developer on the sleeve surface of the developing roller 27 is the photoconductor drum 4. A visible image (image of a developing agent) is formed on the surface of the photoconductor drum 4 by being applied to an electrostatic latent image formed on the surface.

Next, the configuration related to the control of the image forming apparatus 10 will be described. FIG. 4 is a functional block diagram showing a main internal configuration of the image forming apparatus 10. As shown in FIG. 4, the image forming apparatus 10 includes an image reading unit 11, an image forming unit 12, a display unit 41, an operation unit 42, a temperature detection unit 43, a storage unit 44, a cooling fan 48, a control unit 45, and the like. I have. These components are capable of transmitting and receiving data or signals through the bus to each other.

The display unit 41 is a display device such as a liquid crystal display (LCD) or an organic EL (OLED: Organic Light-Emitting Diode) display.

The operation unit 42 includes hard keys such as a numeric keypad, an enter key, and a start key that are input and operated by the user.

Here, the drive unit 47 will be described a little more with reference to FIG. FIG. 5 is a functional block diagram showing a main internal configuration and the like of the drive unit shown in FIG. The drive unit 47 includes a first motor 47A, a first clutch 47B capable of switching between a transmission state in which the rotation of the first motor 47A is transmitted to the developing roller 27 and a cutoff state in which the rotation is cut off, a second motor 47C, and a second. Transmission that transmits the rotation of the second clutch 47D, the third motor 47E, and the third motor 47E to the photoconductor drum 4 that can switch between the transmission state that transmits the rotation of the motor 47C to the spiral feeder 32 and the cutoff state that shuts off. It includes a third clutch 47F that can switch between a state and a cutoff state. The first motor 47A, the second motor 47C, and the third motor 47E are, for example, stepping motors. The first clutch 47B, the second clutch 47D, and the third clutch 47F are, for example, electromagnetic clutches.

For example, the developing roller 27 is rotationally driven in the direction of the arrow by transmitting the rotational force of the first motor 47A to the developing roller 27 via the first clutch 47B in the transmission state. As shown in FIG. 3, the spiral feeder 32 is rotatably supported on the outer wall surface 31E of the developer accommodating portion 31. Each spiral feeder 32 is rotationally driven in the direction of the arrow by transmitting the rotational force of the second motor 47C to the shaft portion 32A of each spiral feeder 32 via the second clutch 47D in the transmission state. The photoconductor drum 4 is rotationally driven in the direction of the arrow by transmitting the rotational force of the third motor 47E to the photoconductor drum 4 via the third clutch 47F in the transmission state.

The temperature detection unit 43 is a temperature sensor that detects the ambient temperature of the developing device 22, and is arranged at a predetermined position of the developing device 22. Specifically, as shown in FIG. 3, the temperature detection unit 43 is a drive input unit (for example, rotation of the first motor 47A) that drives the developing roller 27 and the spiral feeder 32 on the outer wall surface 31E of the developer accommodating unit 31. Is arranged around the input gear G1) transmitted via the first clutch 47B (or may be around the support portion of the spiral feeder 32), and is a developer accommodating portion of the developing apparatus 22. The temperature of the outer wall surface 31E of 31 is detected as the temperature Ti of the developing apparatus 22. Since the rotational force of the first motor 47A is transmitted to the input gear G1 via the first clutch 47B, the heat from the first motor 47A and the first clutch 47B is transmitted to the input gear G1. It is the hottest part of the developer accommodating portion 31. Since this temperature Ti affects the temperature of the developer stored in the developer accommodating portion 31 of the developing apparatus 22, the higher the temperature Ti, the higher the temperature of the developer.

As a cause of raising the temperature of the developer, for example, the heat generated by the first motor 47A or the first clutch 47B is developed by the spiral feeder 32 and the developing agent via the gear mechanism including the input gear G1 and the shaft portion 32A of the spiral feeder 32. It is transmitted to the roller 27 and the like.

The cooling fan 48 takes in air outside the image forming apparatus 10 as cooling air from a suction port (not shown) formed in the housing 10A of the image forming apparatus 10, and the taken-in cooling air is taken in by the developing roller shown in FIG. To cool the sleeve of the developing roller 27 and the photoconductor drum 4 by circulating in the vicinity of the space SP between the sleeve of 27 and the photoconductor drum 4 and along the longitudinal direction of the sleeve of the developing roller 27 and the photoconductor drum 4. I'm a fan of The cooling air is exhausted from an exhaust port (not shown) formed in the housing 10A of the image forming apparatus 10. The cooling air can be a breeze to the extent that the developer supported on the sleeve surface of the developing roller 27 and the surface of the photoconductor drum 4 is not blown away. For example, the cooling fan 48 rotates at a predetermined first rotation speed to obtain the above-mentioned breeze. Further, the cooling fan 48 rotates at a predetermined second rotation speed, which is larger than the first rotation speed, so that a wind stronger than the above-mentioned breeze can be supplied, and the cooling effect is enhanced.

The storage unit 44 is a storage device such as a RAM or a large-capacity HDD (Hard Disk Drive), and stores various data and programs. As shown in FIG. 6, the storage unit 44 stores in advance a determination table used for mode setting and a threshold temperature Tf (for example, 40 ° C.) described later. FIG. 6 is a diagram showing a determination table of the first embodiment. The determination table corresponds to the normal print mode when the drive time ratio Pk of the developing device 22 in the immediately preceding period (for example, 10 minutes) is less than the first threshold time ratio Pf1 (for example, Pf1 = 0.5, that is, 50%). It is a data table to which a cooling mode is associated when the drive time ratio Pk is equal to or greater than the first threshold time ratio Pf1, and is, for example, a lookup table.

The control unit 45 is composed of a processor, a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The processor is, for example, a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an MPU (Micro Processing Unit), or the like. The control unit 45 functions as a control unit 46 and a timekeeping unit 49 when the control program stored in the ROM or the storage unit 44 is executed by the processor.

The timekeeping unit 49 is, for example, a clock such as a real-time clock.

The control unit 45 controls the overall control of the image forming apparatus 10. Further, the control unit 45 is connected to an image reading unit 11, an image forming unit 12, a display unit 41, an operation unit 42, a temperature detection unit 43, a storage unit 44, a cooling fan 48, and the like, and these constituent elements. Controls and sends and receives signals or data to and from each component.

The control unit 46 serves as a processing unit that executes various processes, and also has a function of controlling the display unit 41.

Further, the control unit 46 controls the drive unit 47 in the image forming unit 12 to rotate and drive the developing roller 27, each spiral feeder 32, the photoconductor drum 4, and the like individually.

Further, the control unit 46 controls the cooling fan 48 to circulate the cooling air along the sleeve of the developing roller 27 and the longitudinal direction of the photoconductor drum 4.

When the control unit 46 receives a print job (print request), the control unit 46 limits the operation of the normal print mode or the developing device 22 capable of continuous printing based on the temperature Ti detected by the temperature detection unit 43. The developing device 22 is set to a cooling mode for cooling, and printing related to the print job is executed.

Specifically, when the temperature Ti detected by the temperature detection unit 43 is less than a predetermined threshold temperature Tf (for example, Tf = 40 ° C.), the control unit 46 determines the normal printing mode, that is, the productivity. The developing device 22 is operated at "1 (= 100%)".

Further, when the temperature Ti detected by the temperature detection unit 43 is equal to or higher than the threshold temperature Tf (Ti ≧ Tf), the control unit 46 drives the developing device 22 in the immediately preceding period when the threshold temperature Tf or higher is reached. If the drive time ratio Pk indicating the ratio of is less than the predetermined first threshold time ratio Pf1 (for example, Pf1 = 0.5, that is, 50%), the normal print mode is maintained without setting the cooling mode. If the drive time ratio Pk is equal to or greater than the first threshold time ratio Pf1, the cooling mode is set and the operation of the developing device 22 is limited to "1/4 (= 25%)" in productivity.

FIG. 7A is a diagram for explaining the mode setting at the time when the detected temperature becomes equal to or higher than the threshold temperature. FIG. 7B is a diagram for explaining the mode setting at the mode determination timing after the time when the detection temperature becomes equal to or higher than the threshold temperature. The drive time ratio of the developing device 22 is, for example, the driving time of the developing device 22 in the period immediately before t1 (for example, 10 minutes) when the temperature Ti detected by the temperature detection unit 43 becomes equal to or higher than the threshold temperature Tf (for example, 40 ° C.). Is the ratio. For example, in FIG. 7A, when the developing device 22 is not driven (driving time is “0 minutes”) in the immediately preceding period (for example, 10 minutes), the driving time ratio of the developing device 22 is “0%”. (= 0 minutes / 10 minutes) ”, the control unit 46 determines that the drive time ratio Pk is 0% and is less than the first threshold time ratio Pf1 (50%), and sets the cooling mode. Instead, keep the normal print mode. On the other hand, in the following example shown in FIG. 7A, the developing apparatus 22 is in the period immediately before the time point t1 (for example, 10 minutes) when the temperature Ti detected by the temperature detecting unit 43 becomes equal to or higher than the threshold temperature Tf (for example, 40 ° C.). When is operating for 5 minutes, the drive time ratio Pk of the developing device 22 is 50% (= 5 minutes / 10 minutes), so that the control unit 46 has a drive time ratio Pk of 50%. It is determined that the first threshold time ratio is Pf1 (50%) or more, and the cooling mode is set.

Further, as shown in FIG. 7B, the control unit 46 has a drive time ratio in a period immediately before the mode determination timing t2 (for example, 10 minutes) that arrives at a predetermined cycle after the normal print mode is maintained. When Pk is less than the first threshold time ratio Pf1, the normal print mode is maintained. Here, since the developing device 22 is driven by the start of execution of the print job (for example, 1 minute drive = 10% drive), the drive time ratio Pk is 10%, but the control unit 46 controls the first threshold time ratio Pf1 (for example, 1 minute drive = 10% drive). It is determined that it is less than 50%), and the normal print mode is maintained. Further, at the mode determination timing t3 several times, the developing device 22 is driven (for example, 5 minutes drive = 50% drive) by the start of execution of the print job, so that the drive time ratio Pk is 50%, but the control unit 46 Determines that the first threshold time ratio is Pf1 or more, and sets the above-mentioned cooling mode (here, the cooling mode in which the productivity is limited to "1/4 (= 25%)").

Further, after setting the cooling mode, the control unit 46 returns to the normal print mode when the temperature Ti detected by the temperature detection unit 43 becomes less than the threshold temperature Tf at the mode determination timing that arrives at a predetermined cycle. ..

Further, the storage unit 44 stores the operating period of the developing device 22 as the operating time of the developing device 22 in association with the time measured by the time measuring unit 49 under the control of the control unit 46. The control unit 46 is predetermined from the operation time of the developing device 22 stored in the storage unit 44, the time indicated by the time measuring unit 49 when the threshold temperature Tf or higher is reached, and the time when the threshold temperature Tf or higher is reached. The drive time ratio Pk in the immediately preceding period at the time when the threshold temperature Tf or more is reached is calculated using the immediately preceding period, which is the calculated period, and the calculated drive time ratio Pk is the first threshold time ratio Pf1 or more. Judge whether or not. Thereby, the drive time ratio Pk in the period immediately before the time when the threshold temperature becomes Tf or more can be preferably calculated.

Further, the storage unit 44 stores the operating period of the developing device 22 as the operating time of the developing device 22 in association with the time measured by the time measuring unit 49 under the control of the control unit 46. The control unit 46 uses the operating time of the developing device 22 stored in the storage unit 44, the time indicated by the time measuring unit 49 at the time of mode determination, and the immediately preceding period which is a predetermined period from the time of the mode determination. The drive time ratio Pk in the period immediately before the mode determination is calculated, and it is determined whether or not the calculated drive time ratio Pk is equal to or greater than the first threshold time ratio Pf1. Thereby, the drive time ratio Pk in the period immediately before the mode determination can be preferably calculated.

Further, in the cooling mode, the control unit 46 performs printing related to the print job by deceleration printing (so-called inter-paper standby printing) including a pause period of the printing operation every time one sheet is printed. As a result, the increase in the developing temperature is suppressed as compared with the case where a plurality of sheets are continuously printed in the previous period of 10 minutes and intermittent printing is performed in which the subsequent period, which is the remaining period, is the rest period. it can.

Further, the control unit 46 drives the developing roller 27, each spiral feeder 32, and the photoconductor drum 4 with the first clutch 47B, the second clutch 47D, and the third clutch 47F cut off when the print job is not received. I won't let you. By doing so, it is possible to prevent the temperature rise of the developing device 22 due to the operation during the standby drive. Further, the control unit 46 uses the cooling fan 48 when the temperature detected by the temperature detection unit 43 reaches a predetermined cooling temperature (for example, 35 ° C.) when the print job is not received. It may be operated at a predetermined second rotation speed higher than the first rotation speed in the normal print mode.

Further, the control unit 46 may not drive the developing device 22 during the above-mentioned resting period of the printing operation, which is located during the printing period for each sheet. Specifically, the control unit 46 does not drive the developing roller 27, each spiral feeder 32, and the photoconductor drum 4 with the first clutch 47B, the second clutch 47D, and the third clutch 47F shut off. Therefore, it is possible to prevent heat generation due to the driving of the developing roller 27 and the spiral feeder 32 during the rest period of the printing operation, and to improve the cooling effect. Further, the control unit 46 operates the cooling fan 48 at a predetermined second rotation speed higher than the first rotation speed in the normal print mode during the rest period of the above-mentioned printing operation in the cooling mode. According to this, the cooling effect can be improved.

Further, when the control unit 46 receives a continuous printing job (continuous printing request) instructing printing of a plurality of sheets as a printing job, the control unit 46 sets the printing start timing of the second and subsequent sheets for printing the plurality of sheets. At the time of judgment.

Next, the cooling control of the developing device 22 in the image forming device 10 will be described with reference to the flowchart shown in FIG. FIG. 8 is a flowchart showing cooling control of the developing apparatus in the image forming apparatus of the first embodiment.

First, the control unit 46 determines whether or not there is a print job (print request) for recording the visible image on the recording paper (S101). When the control unit 46 determines that there is no print job (S101 “No”), the control unit 46 ends this process. When the control unit 46 determines that there is a print job (S101 “Yes”), the control unit 46 acquires the temperature Ti of the developer accommodating unit 31 of the developing device 22 detected by the temperature detection unit 43, and this temperature Ti is preset. It is determined whether or not the temperature is equal to or higher than the threshold temperature Tf (S102).

For example, when the control unit 46 determines that the temperature Ti is less than the threshold temperature Tf (S102 “Yes”), the control unit 46 sets the normal print mode (S103). The control unit 46 causes the image forming unit 12 to execute continuous printing for the print job (S104). In the normal printing mode, the cooling fan 48 rotates at the first rotation speed, so that the above breeze is blown along the sleeve of the developing roller 27 and the longitudinal direction of the photoconductor drum 4 even during continuous printing, and the developing roller. The sleeve of 27 and the photoconductor drum 4 can be cooled.

The control unit 46 determines whether or not the print job is completed (S105). The control unit 46 returns to the process of S102 when the print job is not completed (S105 “No”), that is, when continuous printing is not completed for the print job. On the other hand, when the control unit 46 determines that there is no print job, that is, the continuous printing is completed (S105 “Yes”), the control unit 46 ends this process.

By the way, in the process of S102 described above, when the control unit 46 determines that the temperature Ti detected by the temperature detection unit 43 is not less than the threshold temperature Tf, in other words, is equal to or higher than the threshold temperature Tf (S102 “No”), the threshold temperature It is determined whether or not the drive time ratio Pk of the developing device 22 in the immediately preceding period (10 minutes) at the time when the temperature becomes Tf or more is less than the first threshold time ratio Pf1 (50%) (S106). Specifically, the control unit 46 sets the operating time of the developing device 22 stored in the storage unit 44, the time indicated by the time measuring unit 49 when the threshold temperature Tf or higher, and the threshold temperature Tf or higher. Using the immediately preceding period, which is a predetermined period from the time point, and the determination table shown in FIG. 6, the drive time ratio Pk of the developing device 22 in the immediately preceding period (10 minutes) is the first threshold time ratio Pf1 (50%). ) To determine whether or not it is less than.

For example, in the case of the drive 0% shown in FIG. 7A, the control unit 46 has a drive time ratio Pk of 0%, so that the drive time ratio Pk (= 0%) is the first threshold time ratio Pf1 ( If it is determined that the ratio is less than 50%) (S106 “Yes”), the process proceeds to S103 and the continuous printing mode is set (S103).

On the other hand, in the process of S106, in the case of the drive 50% shown in FIG. 7A, the drive time ratio Pk is 50%, so that the drive time ratio Pk (= 50%) is the first. It is determined that the threshold time ratio is Pf1 (50%) or more (S106 “No”), and the cooling mode is set (S107).

After the processing of S107, the control unit 46 determines whether or not the temperature Ti detected by the temperature detection unit 43 is less than the threshold temperature Tf (S108). When the control unit 46 determines that the temperature Ti is less than the threshold temperature Tf (S108 “Yes”), the control unit 46 proceeds to S103 and sets the continuous printing mode (S103).

On the other hand, in the process of S108, when the control unit 46 determines that the temperature Ti is not less than the threshold temperature Tf (S108 “No”), the control unit 46 executes printing (S109). In the process of S109, the control unit 46 executes printing for one sheet related to the print job by deceleration printing (inter-paper standby printing).

After the process of S109, the control unit 46 determines whether or not the print job is completed (S110). For example, the control unit 46 determines whether or not to print the next page for the print job. The control unit 46 proceeds to the process of S106 when the print job is not completed (S110 “No”), that is, when the next page of the print job is printed. On the other hand, in the process of S110, when the control unit 46 determines that there is no print job, that is, there is no printing of the next one page (S110 “Yes”), the control unit 46 ends this process.

As described above, according to the image forming apparatus 10 of the first embodiment, when the temperature Ti detected by the temperature detection unit 43 becomes the threshold temperature Tf or more, the cooling mode is not set immediately, but when the temperature becomes Tf or more. When the drive time ratio Pk of the developing device 22 in the period immediately preceding the above is less than the first threshold time ratio Pf1, the normal print mode is maintained, and when the drive time ratio Pk is equal to or more than the first threshold time ratio Pf1, the cooling mode is set. For example, when the developing device 22 is not operating in the period immediately before the threshold temperature Tf or higher, the actual development temperature deviates to the higher temperature side than the detection temperature Ti of the developer accommodating unit 31. Therefore, it is possible to maintain the normal print mode for a certain period of time. On the other hand, when the developing device 22 is operating for a certain period or longer in the period immediately before the threshold temperature Tf or higher, as shown in FIG. 9, the actual temperature is higher than the detection temperature Ti of the developing agent accommodating portion 31. Since the RD is large enough to deviate from the development temperature to the high temperature side, it is necessary to immediately set the cooling mode. Therefore, when the temperature Ti detected by the temperature detection unit 43 becomes equal to or higher than the threshold temperature Tf, the drive time ratio Pk of the developing device 22 in the immediately preceding period at the time when the temperature becomes equal to or higher than the threshold temperature Tf becomes the first threshold time ratio Pf1. If it is less than, it is possible to prevent the printing productivity from being excessively lowered by maintaining the normal printing mode. That is, it is possible to avoid a decrease in printing productivity as much as possible. On the other hand, when the temperature Ti detected by the temperature detection unit 43 becomes equal to or higher than the threshold temperature Tf, the drive time ratio Pk of the developing apparatus 22 in the immediately preceding period at the time when the temperature becomes Tf or higher is the first threshold time ratio Pf1 or higher. If this is the case, the cooling mode is set to limit the operation of the developing apparatus 22, so that the developing temperature can be suppressed within the upper limit temperature of the developing agent. From the above, the development temperature can be suppressed within the upper limit temperature of the developer for maintaining the performance of the developer and guaranteeing the image quality, and image defects and damage to the image forming apparatus due to thermal deterioration of the developer can be prevented. Further, since printing can be permitted up to the vicinity of the upper limit temperature of the developer even in a high temperature environment, it is possible to avoid a decrease in printing productivity as much as possible and improve convenience.

Further, the control unit 46 performs the normal printing when the drive time ratio Pk in the period immediately before the mode determination timing that arrives at a predetermined cycle after the normal print mode is maintained is less than the first threshold time ratio Pf1. Since the mode is maintained and the cooling mode is set when the first threshold time ratio is Pf1 or higher, the normal print mode can be maintained for an appropriate period after the first temperature threshold is reached, that is, development. The normal printing mode can be maintained for a period in which the actual development temperature deviates to the higher temperature side than the detection temperature Ti of the agent accommodating portion 31. Therefore, the productivity of printing can be improved.

Further, after setting the cooling mode, the control unit 46 returns to the normal print mode when the temperature Ti detected by the temperature detection unit 43 becomes less than the threshold temperature Tf at the mode determination timing that arrives at a predetermined cycle. Therefore, it is possible to return to normal printing at an appropriate timing, and it is possible to secure printing productivity.

Further, when the control unit 46 receives a continuous print request instructing printing of a plurality of sheets as a print job (print request), the control unit 46 sets the print start timing of each sheet as the mode determination time for printing the plurality of sheets. For each print start timing of each sheet, it can be determined whether the drive time ratio Pk of the developing device 22 in the period immediately before the print start timing is equal to or higher than the first threshold time ratio Pf1, and the cooling mode can be set accurately and appropriately. it can.

In the first embodiment, the control unit 46 elapses a predetermined period after setting the cooling mode, or has an upper threshold time ratio of Pf1 or more of the first threshold time ratio (for example, the second embodiment described later). When the third threshold time ratio Pf3) or more of the embodiment is reached, the operation of the developing device 22 may be stopped for a certain period of time.

Next, the image forming apparatus 10 according to the second embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a flowchart showing cooling control in the image forming apparatus of the second embodiment. FIG. 11 is a diagram showing a determination table of the second embodiment. The image forming apparatus 10 according to the first embodiment employs one first threshold time ratio Pf1, but the image forming apparatus 10 according to the second embodiment employs three first threshold time ratios Pf1 and a first. It differs from the first embodiment in that the two threshold time ratio Pf2 and the third threshold time ratio Pf3 are adopted. The same components as those described in the first embodiment are assigned the same numbers, and the description thereof will be omitted.

The storage unit 44 stores the determination table shown in FIG. The determination table shown in FIG. 11 is usually used when the drive time ratio Pk of the developing device 22 in the immediately preceding period (for example, 10 minutes) is less than the first threshold time ratio Pf1 (for example, Pf1 = 0.2, that is, 20%). A print mode is associated with the drive time ratio Pk, which is greater than or equal to the first threshold time ratio Pf1 and larger than the first threshold time ratio Pf1 (for example, Pf1 = 0.5, that is, Pf1 = 0.5, that is, When it is less than 50%), the first cooling mode is associated, and the drive time ratio Pk is equal to or more than the second threshold time ratio Pf2 and larger than the second threshold time ratio Pf2. (For example, Pf1 = 0.8, that is, 80%) is associated with the second cooling mode, and the drive time ratio Pk is associated with the third threshold time ratio Pf3 or more. It is a data table that has been created. The first cooling mode is a cooling mode in which the productivity is limited to "1/2 (= 50%)". The second cooling mode is a cooling mode in which the productivity is limited to "1/4 (= 25%)". The third cooling mode is a cooling mode in which the operation of the developing device 22 is stopped, and the productivity is limited to "0 (= 0%)".

The control unit 46 operates the developing device 22 in the normal print mode when the temperature Ti detected by the temperature detection unit 43 is less than a predetermined threshold temperature Tf. On the other hand, when the temperature Ti detected by the temperature detection unit 43 is equal to or higher than the threshold temperature Tf, the control unit 46 has a first drive time ratio Pk of the developing device 22 in the immediately preceding period when the threshold temperature Tf or higher is reached. If the threshold time ratio is Pf1 or more and less than the second threshold time ratio Pf2, the first cooling mode is set as the cooling mode, and the drive time ratio Pk in the immediately preceding period at the time when the threshold temperature Tf or more becomes the second If the threshold time ratio is Pf2 or more and less than the third threshold time ratio Pf3, the second cooling mode is set as the cooling mode, and the drive time ratio Pk in the immediately preceding period at the time when the threshold temperature Tf or more becomes the third threshold If the time ratio is Pf3 or more, the third cooling mode is set as the cooling mode.

The control unit 46 controls the normal print mode when the drive time ratio Pk in the period immediately preceding the mode determination timing that arrives at a predetermined cycle after the normal print mode is maintained is less than the first threshold time ratio Pf1. If the first threshold time ratio is Pf1 or more and the second threshold time ratio is less than Pf2, the first cooling mode is set, and the second threshold time ratio Pf2 or more and the third threshold time ratio is less than Pf3. For example, the second cooling mode is set, and if the third threshold time ratio is Pf3 or more, the third cooling mode is set.

After setting the cooling mode, the control unit 46 returns to the normal print mode when the temperature Ti detected by the temperature detection unit 43 becomes less than the threshold temperature Tf at the mode determination timing that arrives at a predetermined cycle.

In the second embodiment, since the processes of S121 to S126 in the flowchart of FIG. 10 are different from the flowchart of FIG. 8 of the first embodiment, the processes of S121 to S126 will be described.

In the process of S102 of FIG. 10, when the control unit 46 determines that the temperature Ti detected by the temperature detection unit 43 is not less than the threshold temperature Tf, in other words, is equal to or higher than the threshold temperature Tf (S102 “No”), the threshold temperature Tf It is determined whether or not the drive time ratio Pk of the developing device 22 in the period immediately before (10 minutes) at the time of the above is less than the first threshold time ratio Pf1 (20%) (S121).

When the control unit 46 determines that the drive time ratio Pk is less than the first threshold time ratio Pf1 (20%) (S121 “Yes”), the control unit 46 proceeds to the process of S103 and sets the continuous print mode (S103).

When the control unit 46 determines that the drive time ratio Pk is not less than the first threshold time ratio Pf1 (20%) (S121 “No”), the drive time ratio Pk is equal to or greater than the first threshold time ratio Pf1 and the second threshold value. It is determined whether or not the time ratio is less than Pf2 (S122), and if so (S122 “Yes”), the first cooling mode is set (S123).

On the other hand, when the control unit 46 determines in the processing of S122 that the drive time ratio Pk is equal to or greater than the first threshold time ratio Pf1 and is not less than the second threshold time ratio Pf2 (S122 “No”), the drive time ratio Pk is the second. It is determined whether or not the two threshold time ratio Pf2 or more and the third threshold time ratio is less than Pf3 (S124), and if so (S124 “Yes”), the second cooling mode is set (S125).

On the other hand, when the control unit 46 determines in the processing of S124 that the drive time ratio Pk is equal to or greater than the second threshold time ratio Pf2 and is not less than the third threshold time ratio Pf3 (S124 “No”), that is, the drive time ratio Pk. Is determined to be equal to or greater than the third threshold time ratio Pf3, the third cooling mode is set (S126), and the process proceeds to S110.

The control unit 46 determines whether or not the temperature Ti detected by the temperature detection unit 43 is less than the threshold temperature Tf after the processing of S123 or after the processing of S125 (S108). Since each process of S108 to S110 shown in FIG. 10 is the same as that of the first embodiment, the description thereof will be omitted here.

As described above, according to the image forming apparatus 10 of the second embodiment, when the temperature Ti detected by the temperature detection unit 43 is equal to or higher than the threshold temperature Tf, the driving time in the immediately preceding period at the time when the temperature becomes Tf or higher. A plurality of cooling modes can be set according to the ratio Pk. That is, when the temperature Ti detected by the temperature detection unit 43 is equal to or higher than the threshold temperature Tf, the control unit 46 has a drive time ratio Pk in the immediately preceding period at the time when the threshold temperature Tf or higher becomes the first threshold time ratio Pf1. When the above and the second threshold time ratio is less than Pf2, the first cooling mode is set, and the drive time ratio Pk in the immediately preceding period at the time when the threshold temperature Tf or more becomes the second threshold time ratio Pf2 or more and is the second. Since the second cooling mode is set when the threshold time ratio is less than Pf3, printing can be permitted up to the vicinity of the upper limit temperature of the developer even in a high temperature environment, and printing productivity can be ensured. Further, the control unit 46 is set to the third cooling mode in which the operation of the developing device is stopped when the drive time ratio Pk in the period immediately before the time when the threshold temperature becomes Tf or more is the third threshold time ratio Pf3 or more. Therefore, the development temperature can be suppressed within the upper limit temperature of the developer.

The control unit 46 performs the normal printing when the driving time ratio Pk in the period immediately before the mode determination timing that arrives at a predetermined cycle after the normal printing mode is maintained is less than the first threshold time ratio Pf1. If the mode is maintained and the first threshold time ratio is Pf1 or more and the second threshold time ratio is less than Pf2, the first cooling mode is set, and the second threshold time ratio is Pf2 or more and the third threshold time ratio is less than Pf3. For example, if the second cooling mode is set and the third threshold time ratio is Pf3 or more, the third cooling mode is set. Therefore, the normal printing mode is set in an appropriate period after the first temperature threshold is reached. That is, the normal printing mode can be maintained for a period in which the actual development temperature deviates to the higher temperature side than the detection temperature Ti of the developer accommodating portion. Therefore, the productivity of printing can be improved. Further, even if the second cooling mode or the third cooling mode is set, printing can be performed while the operation is restricted, so that printing can be permitted up to the vicinity of the upper limit temperature of the developer even in a high temperature environment, so that the printing productivity is lowered. Can be avoided as much as possible to improve convenience.

After setting the cooling mode, the control unit 46 returns to the normal print mode when the temperature Ti detected by the temperature detection unit 43 becomes less than the threshold temperature Tf at the mode determination timing that arrives at a predetermined cycle. It is possible to return to normal printing at an appropriate timing, and it is possible to secure printing productivity.

In each of the above embodiments, the control unit 46 drives the cooling fan 48 in the normal printing mode, but it does not have to be driven.

Further, in each of the above embodiments, the drive unit 47 shown in FIG. 5 includes a first clutch 47B, a second clutch 47D, and a third clutch 47F, but may be configured without a clutch. In this case, the control unit 46 may stop the rotation of the first motor 47A, the second motor 47C, and the third motor 47E during the above-mentioned rest period.

Further, as a developer housed in the developer accommodating portion 31, a one-component developer such as a one-component magnetic toner is exemplified, but it is a two-component developer formed by mixing toner and a carrier. Also, the present invention can be applied.

Further, in the above-described embodiment and the like, a multifunction device is exemplified as an embodiment of the image forming apparatus of the present invention, but this is only an example, and may be a copy machine, a printer, a facsimile machine, or the like.

Further, the configuration of the above-described embodiment described with reference to FIGS. 1 to 11 is merely an example of the present invention, and is not intended to limit the present invention to the configuration.

4 Photoreceptor drum (image carrier)
10 Image forming device 22 Developing device 27 Developing roller 31 Developer accommodating unit 32 Spiral feeder (stirring member)
43 Temperature detection unit 44 Storage unit 46 Control unit 49 Timekeeping unit

Claims (10)

An image forming apparatus equipped with a developing apparatus.
The developing device
A developing roller that applies a developer to the electrostatic latent image formed on the image carrier and develops the electrostatic latent image into a visible image.
It has a stirring member that stirs the developer while being conveyed along the developing roller, and has a developing agent accommodating portion that supplies the developing agent to the developing roller.
The image forming apparatus further
A temperature detection unit that detects the temperature of the developer housing unit,
When a print request is received, it is set to a normal printing mode capable of continuous printing or a cooling mode for cooling the developing device by limiting the operation of the developing device based on the temperature detected by the temperature detecting unit. It is equipped with a control unit that executes printing related to the print request.
When the temperature detected by the temperature detecting unit is less than a predetermined threshold temperature, the control unit operates the developing device in the normal printing mode, and the temperature detected by the temperature detecting unit is the threshold temperature. In the above case, if the drive time ratio indicating the ratio of the drive time of the developing device in the period immediately before the time when the threshold temperature becomes equal to or higher than the threshold temperature is less than the predetermined first threshold time ratio, the cooling mode is set. An image forming apparatus that maintains the normal printing mode without doing so, and if the driving time ratio is equal to or greater than the first threshold time ratio, sets the cooling mode to limit the operation of the developing apparatus. The control unit performs the normal printing when the driving time ratio in the period immediately before the mode determination timing that arrives at a predetermined cycle after the normal printing mode is maintained is less than the first threshold time ratio. The image forming apparatus according to claim 1, wherein the mode is maintained and the cooling mode is set when the ratio is equal to or greater than the first threshold time ratio. After setting the cooling mode, the control unit claims to return to the normal print mode when the temperature detected by the temperature detection unit becomes less than the threshold temperature at the mode determination timing that arrives at a predetermined cycle. The image forming apparatus according to claim 1 or 2. An image forming apparatus equipped with a developing apparatus.
The developing device
A developing roller that applies a developer to the electrostatic latent image formed on the image carrier and develops the electrostatic latent image into a visible image.
It has a stirring member that stirs the developer while being conveyed along the developing roller, and has a developing agent accommodating portion that supplies the developing agent to the developing roller.
The image forming apparatus further
A temperature detection unit that detects the temperature of the developer housing unit,
When a print request is received, it is set to a normal printing mode capable of continuous printing or a cooling mode for cooling the developing device by limiting the operation of the developing device based on the temperature detected by the temperature detecting unit. It is equipped with a control unit that executes printing related to the print request.
When the temperature detected by the temperature detection unit is less than a predetermined threshold temperature, the control unit operates the development device in the normal print mode, and the control unit detects the temperature detection unit. When the temperature is equal to or higher than the threshold temperature, the drive time ratio in the period immediately preceding the time when the threshold temperature is equal to or higher is equal to or higher than the first threshold time ratio and larger than the first threshold time ratio. If it is less than the second threshold time ratio, the first cooling mode is set as the cooling mode, and the drive time ratio in the period immediately before the time when the threshold temperature becomes equal to or higher is equal to or higher than the second threshold time ratio. If it is larger than the second threshold time ratio and less than a predetermined third threshold time ratio, the cooling mode is set to the second cooling mode in which the operation is restricted compared to the first cooling mode, and the threshold temperature or higher is set. If the drive time ratio in the period immediately before the time is equal to or greater than the third threshold time ratio, the image forming apparatus is set to the third cooling mode in which the operation of the developing device is stopped as the cooling mode. The control unit performs the normal printing when the driving time ratio in the period immediately before the mode determination timing that arrives at a predetermined cycle after the normal printing mode is maintained is less than the first threshold time ratio. If the mode is maintained and is equal to or greater than the first threshold time ratio and less than the second threshold time ratio, the mode is set to the first cooling mode, and is equal to or greater than the second threshold time ratio and less than the third threshold time ratio. The image forming apparatus according to claim 4, wherein if the case is set to the second cooling mode, and if the ratio is equal to or higher than the third threshold time ratio, the third cooling mode is set. After setting the cooling mode, the control unit claims to return to the normal print mode when the temperature detected by the temperature detection unit becomes less than the threshold temperature at the mode determination timing that arrives at a predetermined cycle. The image forming apparatus according to claim 4 or 5. The control unit according to any one of claims 1 to 6, wherein in the cooling mode, the printing related to the printing request is performed by deceleration printing including a pause period of the printing operation every time one sheet is printed. Image forming device. When the control unit receives a continuous printing request instructing printing of a plurality of sheets as the printing request, the control unit requests that the printing start timing of the second and subsequent sheets for printing the plurality of sheets be the mode determination time. 2. The image forming apparatus according to any one of claims 3, 5, 5 and 6. Timekeeping part and timekeeping
A storage unit that records the operating period of the developing device as the operating time of the developing device in association with the time measured by the time measuring unit is provided.
The control unit is predetermined from the operating time of the developing device stored in the storage unit, the time indicated by the timekeeping unit when the temperature exceeds the threshold temperature, and the time when the temperature exceeds the threshold temperature. Using the immediately preceding period, which is a period, the driving time ratio in the immediately preceding period at the time when the threshold temperature becomes equal to or higher is calculated, and whether or not the calculated driving time ratio is equal to or higher than the first threshold time ratio. The image forming apparatus according to any one of claims 1 to 8. Timekeeping part and timekeeping
A storage unit that records the operating period of the developing device as the operating time of the developing device in association with the time measured by the time measuring unit is provided.
The control unit uses the operating time of the developing device stored in the storage unit, the time indicated by the time measuring unit at the time of mode determination, and the immediately preceding period which is a predetermined period from the mode determination. 2. The driving time ratio in the period immediately before the mode determination is calculated, and it is determined whether or not the calculated driving time ratio is equal to or greater than the first threshold time ratio. The image forming apparatus according to any one of claims 6.

Images