JP7342622B2 - Image forming device - Google Patents

Description

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

In the developing device of the image forming apparatus, the developer is conveyed while being stirred, and the developer is applied to the electrostatic latent image on the image carrier through a developing roller to make the electrostatic latent image on the image carrier visible. It is developed into an image (developer image). For example, in an image forming apparatus, when the temperature of the developing device that carries and transports developer increases due to continuous printing, etc., the printing operation is restricted or interrupted to prevent thermal deterioration of the developer. Cooling takes place.

For example, in the image forming apparatus described in Patent Document 1, the temperature inside or around the developing device is detected, and when the detected temperature exceeds a threshold temperature, the number of pages that can be continuously formed is limited to a predetermined number or less. The intermittent printing operation mode is set, and then, when the detected temperature in the intermittent printing operation mode becomes less than a release temperature that is lower than the above-mentioned threshold temperature, the restriction on the number of pages on which continuous image formation can be performed is canceled.

Patent No. 5863011

However, in Patent Document 1, the number of pages that can be continuously printed is not completely proportional to the amount of heat that causes the temperature of the developer to rise, and even when the number of pages that can be continuously printed is limited, the number of pages that can be continuously printed is The temperature may exceed the threshold temperature and thermal deterioration of the developer may not be prevented. Furthermore, if there is a discrepancy between the detected temperature of the developing device and the temperature of the part of the developer that is exposed to the highest temperature, the temperature of the developer may exceed the upper limit temperature of the developer, causing thermal deterioration of the developer. increases. However, if the threshold temperature is lowered, thermal deterioration of the developer will be reduced, but printing will be restricted or interrupted more than necessary, and convenience will be significantly hindered, so lowering the threshold temperature is not recommended. is not desirable.

Furthermore, due to the effects of global warming in recent years, examples of use in high-temperature environments are increasing, and the melt viscosity of developers is becoming lower in order to comply with environmental regulations. For this reason, it is expected that there will be an increase in cases where printing is restricted or interrupted and convenience is hampered.

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 developer while avoiding a decrease in printing productivity as much as possible.

An image forming apparatus according to one aspect of the present invention is an image forming apparatus including a developing device, an external temperature detecting section, and a control section, wherein the developing device applies an electrostatic latent image formed on an image carrier. It has a developing roller that applies a developer to develop the electrostatic latent image into a visible image, and a stirring member that stirs the developer while conveying it along the developing roller. It is arranged around a developer storage unit that supplies the roller and a drive input unit that drives the developing roller and the stirring member on the outer wall surface of the developer storage unit, and controls the temperature of the outer wall surface of the developer storage unit. an internal temperature detection unit that detects the internal temperature of the machine, the external temperature detection unit detects the temperature outside the image forming apparatus, and the control unit that detects the internal temperature detected by the internal temperature detection unit. When the temperature is lower than a predetermined first threshold temperature, cooling control is performed by setting a first cooling mode in which continuous printing is possible, and when the temperature is set to the first cooling mode, the internal temperature detection section If the period ta during which the detected internal temperature is equal to or higher than the first threshold temperature continues for longer than the fastest image forming cycle Tm (seconds) (however, the maximum number of printed sheets per minute Pmax (sheets/minute), the fastest image forming cycle Tm = 60/Pmax), enters a second cooling mode in which intermittent printing is performed at a development drive duty ratio determined by the inside temperature detected by the inside temperature detection section and the outside temperature detected by the outside temperature detection section. This setting is used to perform cooling control.

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.

1 is a sectional view showing an embodiment of an image forming apparatus of the present invention. FIG. 2 is a longitudinal cross-sectional view showing a photoreceptor drum, a developing device, and the like in the image forming apparatus of the present embodiment. FIG. 3 is a cross-sectional view showing a developer storage section of the developing device. FIG. 2 is a functional block diagram showing the main internal configuration of the image forming apparatus. FIG. 5 is a functional block diagram showing the main internal configuration of the drive section shown in FIG. 4. FIG. FIG. 3 is a diagram showing a reference table for specifying a developing drive duty ratio. FIG. 3 is a diagram for explaining a developing drive duty ratio expressed as a ratio between printable time and print standby time. 3 is a flowchart showing cooling control of a developing device in an image forming apparatus. It is a figure which shows the reference table after a change in the 1st modification. It is a flowchart which shows cooling control of the developing device in a 3rd modification.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 10 includes an image reading section 11 and an image forming section 12.

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

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

Thereafter, 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 longitudinal sectional view showing a set of photosensitive drums 4, developing devices 22, etc. in each of the image forming units 3M, 3C, 3Y, and 3Bk. Further, FIG. 3 is a cross-sectional view showing the developer storage section 31 of the developing device 22. As shown in FIG.

As shown in FIG. 2, each of the image forming units 3M, 3C, 3Y, and 3Bk is provided with a photosensitive drum 4, a developing device 22, a primary transfer roller 6, and the like. Around the photoconductor drum 4, there is a static eliminator 24 that eliminates static electricity from the surface of the photoconductor drum 4, a cleaning section 25 that cleans toner remaining on the surface of the photoconductor drum 4, and a cleaning section 25 that uniformly charges the surface of the photoconductor drum 4. A charging section 26, an exposing section 23 for forming an electrostatic latent image on the surface of the photoreceptor drum 4, and the like are provided. The developing device 22 is provided with a developing roller 27, a layer regulating member 28, a developer accommodating section 31 containing developer, two spiral feeders 32 that circulate and transport the developer, and the like. Note that the spiral feeder 32 is an example of a stirring member in the claims.

In this embodiment, a one-component magnetic toner is used as the developer contained in the developer storage section 31 of the developing device 22. The developing roller 27 includes a sleeve made of metal such as aluminum, and a magnet having a developing pole, a layer regulating pole, etc. provided inside the sleeve. Furthermore, the surface of the sleeve of the developing roller 27 is formed with unevenness having a predetermined roughness in order to stabilize the conveyance of the developer.

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, and generates a magnetic field between the layer regulating pole of the magnet in the developing roller 27 and the developing roller 27 due to the gap with the sleeve of the developing roller 27. A thin layer of developer is formed on the surface of 27.

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

In the supply conveyance path 31A, the developer is transported by the spiral feeder 32 of the supply conveyance path 31A from the upstream side in the developer conveyance direction to the downstream side in the conveyance direction (from one end side of the developing roller 27 to the other end side) in the direction of the arrow. The toner is stirred while being conveyed to the developer roller 27, and then sent out to the reflux conveyance path 31B through one connecting path 31C. In addition, in the reflux conveyance path 31B, the developer is stirred while being conveyed by the spiral feeder 32 of the reflux conveyance path 31B in a direction opposite to the conveyance direction in the supply conveyance path 31A, and then passes through the other connecting path 31D to the supply conveyance path. Returned to 31A. Thereby, the developer is supplied to the developing roller 27 while being circulated and conveyed.

The developer storage section 31 is provided with a developer replenishment port (not shown), and the amount of developer stored in the developer storage section 31 is maintained by replenishing the developer through this replenishment port. be done.

The developing roller 27 and the photosensitive drum 4 are rotationally driven in the direction of the arrow by a drive section 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 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 applied to the photoreceptor drum 4 . A visible image (developer image) is formed on the surface of the photoreceptor drum 4 by being added to the electrostatic latent image formed on the surface.

Next, a configuration related to control of the image forming apparatus 10 will be described. FIG. 4 is a functional block diagram showing the main internal configuration of the image forming apparatus 10. As shown in FIG. As shown in FIG. 4, the image forming apparatus 10 includes an image reading section 11, an image forming section 12, a display section 41, an operation section 42, an internal temperature detecting section 43, an external temperature detecting section 49, a storage section 44, and a cooling fan. 48, a control unit 45, and the like. These components are capable of transmitting and receiving data or signals to and from each other via a bus.

The display unit 41 is a display device such as a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display.

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

Here, the drive section 47 will be explained a little more using FIG. 5. FIG. 5 is a functional block diagram showing the main internal configuration of the drive section shown in FIG. 4. As shown in FIG. The drive unit 47 includes a first motor 47A, a first clutch 47B that can be switched between a transmission state in which the rotation of the first motor 47A is transmitted to the developing roller 27 and the spiral feeder 32 and a cutoff state in which it is interrupted, and a second motor 47E. and a second clutch 47F that can be switched between a transmission state in which the rotation of the second motor 47E is transmitted to the photoreceptor drum 4 and a cutoff state in which the rotation is interrupted. The first motor 47A and the second motor 47E are, for example, stepping motors. The first clutch 47B and the second clutch 47F are, for example, electromagnetic clutches. Note that the first motor 47A is an example of a motor in the claims, and the first clutch 47B is an example of a clutch in the claims.

For example, the developing roller 27 is rotationally driven in the direction of the arrow by the rotational force of the first motor 47A being transmitted 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 an outer wall surface 31E of the developer storage section 31. As shown in FIG. Each spiral feeder 32 is rotationally driven in the direction of the arrow by transmitting the rotational force by the first motor 47A to the shaft portion 32A of each spiral feeder 32 via the first clutch 47B in the transmission state. The photosensitive drum 4 is rotationally driven in the direction of the arrow by the rotational force of the second motor 47E being transmitted to the photosensitive drum 4 via the second clutch 47F in the transmission state.

The internal temperature detection section 43 is a temperature sensor that detects the temperature around the developer, and is arranged at a predetermined position inside the image forming apparatus 10. Specifically, as shown in FIG. 3, the in-machine temperature detection section 43 is connected to a drive input section (for example, a drive input section 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 storage section 31. It is arranged around the input gear G1) whose rotation is transmitted via the first clutch 47B, and the temperature of the outer wall surface 31E of the developer storage section 31 of the developing device 22 is adjusted to the internal temperature Ti of the image forming apparatus 10. Detected as. In addition, since the input gear G1 is configured such that the rotational force of the first motor 47A is transmitted via the first clutch 47B, heat from the first motor 47A and the first clutch 47B is transmitted. This is the part of the developer storage section 31 that has the highest temperature. This in-machine temperature Ti affects the temperature of the developer stored in the developer storage section 31 of the developing device 22, so the higher the in-machine temperature Ti becomes, the higher the temperature of the developer becomes.

Note that the cause of the temperature rise of the developer is, for example, when heat from the first motor 47A or the first clutch 47B is transmitted to the spiral feeder 32 and the developer via the gear mechanism including the input gear G1 and the shaft portion 32A of the spiral feeder 32. For example, it may be transmitted to the roller 27.

The external temperature detection unit 49 is a temperature sensor that detects the temperature outside the image forming apparatus 10, and is arranged at a predetermined position outside the image forming apparatus 10. For example, the external temperature detection section 49 is disposed at a predetermined location on the outer surface of the casing 10A of the image forming apparatus 10 (for example, a location around the suction port of the casing 10A), and 10 is detected as the external temperature To of the image forming apparatus 10.

The cooling fan 48 takes in air from outside the image forming apparatus 10 as cooling air from a suction port (not shown) formed in the casing 10A of the image forming apparatus 10, and uses the taken in cooling air to pass through the developing roller shown in FIG. In order to cool the sleeve of the developing roller 27 and the photosensitive drum 4 by circulating it near the space SP between the sleeve of the developing roller 27 and the photosensitive drum 4 and along the longitudinal direction of the sleeve of the developing roller 27 and the photosensitive drum 4. I'm a fan of. The cooling air is exhausted from an exhaust port (not shown) formed in the casing 10A of the image forming apparatus 10. The cooling air can be so small that the developer carried on the sleeve surface of the developing roller 27 and the surface of the photoreceptor drum 4 is not blown away. For example, the cooling fan 48 generates the above-mentioned breeze by rotating at a predetermined first rotation speed.

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 reference table for specifying the development drive duty ratio of the development device 22, and a first threshold temperature Tf and a second threshold temperature Ts, which will be described later. FIG. 6 is a diagram showing a reference table for specifying the development drive duty ratio. The reference table is a data table showing the correspondence between the input data, which is the internal temperature Ti and the external temperature To, and the output data, which is the developing drive duty ratio, and is, for example, a look-up table. In the reference table, a plurality of internal temperatures Ti and a plurality of external temperatures To are stored, and a developing drive duty ratio uniquely determined by the internal temperature Ti and the external temperature To is determined based on the internal temperature Ti and the external temperature To. It is stored in association with each combination with the outside temperature To. For example, as shown in FIG. 6, when the internal temperature Ti is 39° C. and the external temperature To is 30° C. or more and less than 35° C., the developing drive duty ratio is specified as 50%. The development drive duty ratio is preset within a range that does not exceed the upper limit temperature of the developer. Note that the external temperature To in the reference table may be set in 1°C increments.

FIG. 7 is a diagram for explaining the developing drive duty ratio, which is represented by the ratio of printable time to print standby time. The development drive duty ratio is the proportion of the printable time t in a predetermined period T (for example, 60 seconds). For example, if the printable time t is 12 seconds, the development drive duty ratio is 20%.

The control unit 45 includes 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), or an MPU (Micro Processing Unit). This control unit 45 functions as a control section 46 when a control program stored in the ROM or storage section 44 is executed by the processor.

Control unit 45 manages overall control of image forming apparatus 10 . The control unit 45 is also connected to the image reading section 11, the image forming section 12, the display section 41, the operation section 42, the inside temperature detection section 43, the outside temperature detection section 49, the storage section 44, the cooling fan 48, etc. It controls these components and sends and receives signals and 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 individually rotationally drive the developing roller 27, each spiral feeder 32, the photoreceptor drum 4, and the like.

Furthermore, the control unit 46 controls the cooling fan 48 to cause cooling air to flow along the sleeve of the developing roller 27 and the photosensitive drum 4 in the longitudinal direction.

The control unit 46 sets the first cooling mode or the second cooling mode as the cooling mode for cooling the developing device 22.

Specifically, when the in-machine temperature Ti detected by the in-machine temperature detection unit 43 is less than a predetermined first threshold temperature Tf (for example, Tf=39°C) (Ti<Tf), the control unit 46 Cooling control is performed by setting the first cooling mode in which continuous printing is possible.

Further, when the cabin temperature Ti detected by the cabin temperature detection unit 43 is equal to or higher than the first threshold temperature Tf (Ti≧Tf), the control unit 46 uses the reference table to Cooling control is performed by setting the second cooling mode in which intermittent printing is performed at a development drive duty ratio determined by the temperature Ti and the external temperature To detected by the external temperature detection section 49. Specifically, in the second cooling mode, the control unit 46 responds to a print request by setting a printable time t and a print standby time that are set within a range that does not exceed the developer upper limit temperature every predetermined cycle T. Intermittent printing is performed with a development drive duty ratio set to (Tt). For example, as shown in FIG. 6, when the in-machine temperature Ti detected by the in-machine temperature detection unit 43 is 39° C., the control unit 46 determines that the in-machine temperature Ti is equal to or higher than the first threshold temperature Tf, and When Ti is 39° C. and outside temperature To is 32° C., the development drive duty ratio is determined to be 50% using a reference table.

Further, the control unit 46 drives the developing device 22 during the printable time t, and does not drive the developing device 22 during the printing standby time (Tt). Specifically, the control unit 46 sets the first clutch 47B in the transmission state to drive the developing roller 27 and each spiral feeder 32 during the printable time t, and also sets the second clutch 47F in the transmission state to drive the photoreceptor drum. During the printing standby time (Tt), the first clutch 47B and the second clutch 47F are disconnected, and the developing roller 27, each spiral feeder 32, and the photosensitive drum 4 are not driven.

When set to the second cooling mode, the control unit 46 sets the in-machine temperature Ti detected by the in-machine temperature detection unit 43 to a predetermined second threshold temperature Ts (for example, Ts) that is lower than the first threshold temperature Tf. =38.5°C), the first cooling mode is returned to perform cooling control.

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

First, the control unit 46 acquires the temperature of the outer wall surface 31E of the developer storage section 31 of the developing device 22 detected by the internal temperature detection unit 43 as the internal temperature Ti of the image forming apparatus 10, and this internal temperature Ti is set in advance. It is determined whether the temperature is equal to or higher than a set fan operation threshold temperature T1 (for example, 35° C.) (S101). When the control unit 46 determines that the internal temperature Ti is equal to or higher than the fan operation threshold temperature T1 (S101 "Yes"), the control unit 46 drives the cooling fan 48 (S102). For example, the control unit 46 rotates the cooling fan 48 at the predetermined first rotation speed. On the other hand, if the control unit 46 determines that the internal temperature Ti is less than the fan operation threshold temperature T1 (S101 "No"), the control unit 46 stops the cooling fan 48 (S103).

The control unit 46 determines whether there is a print job (print request) for recording a visible image on recording paper (S104). If the control unit 46 determines that there is no print job (S104 "No"), it ends this process. When the control unit 46 determines that there is a print job (S104 “Yes”), the control unit 46 determines whether the internal temperature Ti detected by the internal temperature detection unit 43 is equal to or higher than a preset first threshold temperature Tf. (S105).

For example, if the control unit 46 determines that the internal temperature Ti is less than the first threshold temperature Tf (S105 "Yes"), the control unit 46 sets the first cooling mode (S106). The control unit 46 causes the image forming unit 12 to execute continuous printing for the print job (S107). In the present embodiment, in the first cooling mode and the second cooling mode, when the internal temperature Ti is equal to or higher than the fan operation threshold temperature T1, the cooling fan 48 rotates at the first rotation speed, so that during continuous printing, the cooling fan 48 rotates at the first rotation speed. The above-mentioned breeze is also caused to flow along the longitudinal direction of the sleeve of the developing roller 27 and the photosensitive drum 4, thereby cooling the sleeve of the developing roller 27 and the photosensitive drum 4.

The control unit 46 determines whether the print job is finished (S108). If the print job has not ended (S108 "No"), that is, if the continuous printing of the print job has not ended, the control unit 46 returns to the process of S105. On the other hand, if the control unit 46 determines that there is no print job, that is, that continuous printing has ended (S108 "Yes"), it ends this process.

By the way, in the process of S105 described above, when the control unit 46 determines that the internal temperature Ti is not less than the first threshold temperature Tf, in other words, it is equal to or higher than the first threshold temperature Tf (S105 "No"), the developer storage section It is assumed that the temperature of the developer No. 31 is high, and the second cooling mode is set (S109). Subsequently, the control unit 46 acquires the temperature detected by the external temperature detection unit 49 as the external temperature To of the image forming apparatus 10 (S110). Then, the control unit 46 uses the detected internal temperature Ti and external temperature To and the reference table shown in FIG. is specified (S111). For example, as shown in FIG. 6, when the internal temperature Ti is 39° C. and the external temperature To is 30° C. or more and less than 35° C., the control unit 46 specifies the developing drive duty ratio as 50%. .

As shown in FIG. 7, the control unit 46 determines whether or not the present time is the printable time (S112), and if it is determined that the current time is the printable time (S112 "Yes"), the specified development drive duty is The developing device 22 or the like is caused to perform intermittent printing at a ratio (here, 50%) (S113). Note that if the control unit 46 determines that it is not the printable time (S112 "No"), the process returns to S112.

The control unit 46 determines whether the print job is finished (S114). If the print job has not ended (S114 "No"), that is, if intermittent printing has not ended for the print job, the control unit 46 determines whether the internal temperature Ti is less than the second threshold temperature Ts. (S115). When the control unit 46 determines that the internal temperature Ti is less than the second threshold temperature Ts (S115 "Yes"), the process proceeds to S106. On the other hand, if the control unit 46 determines that the internal temperature Ti is not less than the second threshold temperature Ts (S115 "No"), the process proceeds to S110. On the other hand, in the process of S114, if the control unit 46 determines that there is no print job, that is, that intermittent printing has ended (S114 "Yes"), this process ends.

As described above, according to the image forming apparatus 10 of the present embodiment, a power input section (for example, The temperature of the input gear G1) is higher than other parts, and the temperature at this part is detected by the machine internal temperature detection section 43 as the machine internal temperature Ti, so the temperature at or near the part where the developer is exposed to the highest temperature , and the discrepancy between the internal temperature Ti detected by the internal temperature detection section 43 and the temperature of the portion of the developer exposed to the highest temperature can be reduced. In addition, when the inside temperature Ti detected by the inside temperature detection section 43 is equal to or higher than the first threshold temperature Tf, the control section 46 controls the inside temperature Ti detected by the inside temperature detection section 43 and the outside temperature detection section 49. Cooling control is performed by setting the second cooling mode to perform intermittent printing at the development drive duty ratio determined by the external temperature To, which maintains developer performance and guarantees image quality. The development temperature can be suppressed to within the upper limit temperature, and thermal deterioration of the developer can be appropriately reduced. Therefore, image defects and damage to the image forming apparatus due to developer deterioration can be prevented. Further, since printing can be permitted up to near 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.

Moreover, when the control unit 46 is set to the second cooling mode and the internal temperature Ti detected by the internal temperature detection unit 43 is less than the second threshold temperature Ts, which is lower than the first threshold temperature Tf, Since cooling control is performed by returning to the first cooling mode, unstable mode transitions can be reduced compared to a configuration in which the first cooling mode is returned only by the first threshold temperature Tf. The printing operation behavior when returning to the first cooling mode can be reduced.

In addition, in the second cooling mode, the control unit 46 responds to a print request with a printable time t and a print standby time (T- Since intermittent printing is performed with a development drive duty ratio set to t), the development temperature can be suppressed to within the upper limit temperature of the developer, and thermal deterioration of the developer can be appropriately reduced.

Further, since the control unit 46 drives the developing device 22 during the printable time t and does not drive the developing device 22 during the printing standby time (Tt), the developing device 22 is driven during the printing standby time (Tt). It is possible to prevent heat generation caused by Therefore, the cooling effect during printing standby time (Tt) can be improved.

Further, the control unit 46 sets the first clutch 47B in a transmission state to drive the developing device 22 and the spiral feeder 32 during the printable time t, and sets the first clutch 47B in a disengaged state during the print standby time (Tt). Since the developing device 22 and the spiral feeder 32 are not driven, it is possible to prevent heat generation due to the driving of the developing roller and the spiral feeder 32 during the printing standby time (Tt). Therefore, the cooling effect during printing standby time (Tt) can be improved.

Furthermore, the storage unit 44 stores in advance a reference table showing the correspondence between the input data, which is the internal temperature Ti and the external temperature To, and the output data, which is the developing drive duty ratio. The control unit 46 uses the internal temperature Ti detected by the internal temperature detection unit 43, the external temperature To detected by the external temperature detection unit 49, and the reference table stored in the storage unit 44 to determine the developing drive duty ratio. Identify. Thereby, the developing drive duty ratio can be suitably specified.

In the above embodiment, as shown in FIG. is arranged around the input gear G1) whose rotation is transmitted via the first clutch 47B, and the temperature of the outer wall surface 31E of the developer storage section 31 is detected as the internal temperature Ti of the image forming apparatus 10. However, it is not limited to this. The in-machine temperature detection section 43 is connected to a drive input section (for example, the rotation of the first motor 47A) that drives the developing roller 27 and the spiral feeder 32 at a location indicated by a broken line in FIG. may be arranged around the input gear G1) that is transmitted via the first clutch 47B, and the temperature of the inner wall surface 31F of the developer storage section 31 may be detected as the internal temperature Ti. Further, the in-machine temperature detection section 43 may be disposed at a location where the developing roller 27 is supported on the inner wall surface 31F of the developer storage section 31, and may detect the surface temperature of the sleeve of the developing roller 27 as the in-machine temperature Ti. In these cases, the temperature of the area around the support area of the spiral feeder 32 or the area around the support area of the developing roller 27 on the inner wall surface 31F of the developer storage section 31 is higher than other areas, and Since the internal temperature detection section 43 detects the temperature, it is possible to detect the temperature of the part where the developer is exposed to the highest temperature or the temperature in the vicinity thereof, and the internal temperature detected by the internal temperature detection section 43 and the temperature of the developer at the highest temperature can be detected. It is possible to reduce the deviation from the temperature of the part exposed to the temperature.

<First modification example>
The image forming apparatus 10 of the first modification is capable of accepting changes to the setting values of the reference table by the administrator. Specifically, input operations are performed on the operation unit 42 by the administrator. The administrator is, for example, a service person, a supervisor, or the like who has authority to change the settings of the image forming apparatus 10. The storage unit 44 stores in advance administrator confirmation information such as a password known only to the administrator. The control unit 46 determines that the person is the administrator when the information input to the operation unit 42 (for example, name and password) matches the password stored in the storage unit 44 (for example, name and authentication password).

When the control unit 46 performs an operation to change the setting value of the reference table on the operation unit 42 when it is determined that the administrator is the administrator, the control unit 46 stores the changed reference table separately from the reference table in the storage unit. 44. FIG. 9 is a diagram showing a reference table after modification in the first modification. The revised reference table shows three developing drive duty ratios when the machine internal temperature Ti is 39°C and the external temperature To is 25°C or more and less than 40°C, and when the machine internal temperature Ti is 40°C and the machine external temperature To is 25°C or more and less than 40°C. Three developing drive duty ratios are changed when the external temperature To is 25° C. or more and less than 40° C. Note that the set values of the first threshold temperature Tf and the second threshold temperature Ts may be changed.

Then, the control unit 46 uses the inside temperature Ti detected by the inside temperature detection unit 43, the outside temperature To detected by the outside temperature detection unit 49, and the changed reference table shown in FIG. Specify the drive duty ratio.

Thereby, the changed reference table can be added to the storage unit 44 by the administrator, and the development drive duty ratio can be suitably specified from the changed reference table.

Note that the image forming apparatus 10 may be configured to be able to select one reference table from among a plurality of types of reference tables. For example, the storage unit 44 stores in advance a high temperature environment reference table, a medium temperature environment reference table, and a low temperature environment reference table as a plurality of types of reference tables corresponding to the usage environment of the image forming apparatus 10. Then, when the control unit 46 performs a selection operation of a reference table on the operation unit 42 when it is determined that the administrator is the administrator, the control unit 46 registers the selected reference table as an effective reference table. The developing drive duty ratio is specified using the registered reference table, the internal temperature Ti, and the external temperature To. Further, the control unit 46 selects a reference table from among the plurality of types of reference tables to which the operating environment temperature of the image forming apparatus 10 input by the administrator or the external temperature To detected by the external temperature detection unit 49 corresponds. select. For example, when the operating environment temperature of the image forming apparatus 10 input by the administrator is "high temperature", the control unit 46 selects a high temperature environment reference table corresponding to "high temperature" from among multiple types of reference tables. Choose from among them. Thereby, a reference table suitable for the usage environment of the image forming apparatus 10 can be selected.

<Second modification example>
In the above embodiment, in the process of S105 shown in FIG. 8, when the internal temperature Ti becomes equal to or higher than the first threshold temperature Tf, the control unit 46 immediately shifts from the first cooling mode to the second cooling mode, and in the process of S115, When the internal temperature Ti becomes less than the second threshold temperature Ts, the second cooling mode is immediately returned to the first cooling mode. On the other hand, in the image forming apparatus 10 of the second modification, the period in which the internal temperature Ti exceeds the first threshold temperature Tf in the first cooling mode continues for a period longer than the time required to print one sheet of recording paper. In this case, the first cooling mode is shifted to the second cooling mode, and the period during which the internal temperature Ti is lower than the second threshold temperature Ts in the second cooling mode continues for a period longer than the time required to print one sheet of recording paper. In this case, the second cooling mode is returned to the first cooling mode.

In the process of S105 shown in FIG. 8, the control unit 46 determines that if the period ta during which the internal temperature Ti detected by the internal temperature detection unit 43 is equal to or higher than the first threshold temperature Tf continues for longer than the fastest image forming cycle Tm (seconds) ( However, when the maximum number of sheets printed per minute is Pmax (sheets/min) and the fastest image forming cycle Tm is 60/Pmax (S105 "No"), the internal temperature Ti and the external temperature detected by the internal temperature detection section 43 are Cooling control is performed by setting a second cooling mode in which intermittent printing is performed at a development drive duty ratio determined by the external temperature To detected by the detection unit 49. For example, if the image forming apparatus 10 has a printing capacity of 40 sheets/minute, that is, it is a 40-sheet machine, the maximum number of sheets printed per minute Pmax=40 (sheets/minute), and the fastest image forming cycle Tm is: From the formula Tm=60/Pmax, Tm=60/40=1.5 seconds, so when the period ta becomes 1.5 seconds or more, the second cooling mode is set.

According to the above configuration, when the first cooling mode is set, if the period ta during which the internal temperature Ti is equal to or higher than the first threshold temperature Tf continues for longer than the fastest image forming cycle Tm (seconds), that is, If the process continues for more than the time required to print one sheet of recording paper (S105 "No"), the first cooling mode shifts to the second cooling mode (S109), thereby preventing unstable mode transitions. This makes it possible to stabilize the printing operation behavior when transitioning from the first cooling mode to the second cooling mode.

Moreover, when the control unit 46 is set to the second cooling mode, specifically, in the process of S115 shown in FIG. If the period tb during which the temperature is lower than the predetermined second threshold temperature Ts continues for the fastest image forming period Tm (seconds) or more (S115 "Yes"), the first cooling mode is returned to perform cooling control. . For example, if the image forming apparatus 10 is the above-mentioned 40-sheet machine, the first cooling mode is returned when the period tb becomes 1.5 seconds or more.

According to the above configuration, when the second cooling mode is set, the period tb during which the in-machine temperature Ti detected by the in-machine temperature detection section 43 is less than the second threshold temperature Ts, which is lower than the first threshold temperature Tf, is When the fastest image forming period Tm (seconds) or more continues (S115 "Yes"), the first cooling mode is returned (S106) and cooling control is performed, so that unstable mode transition can be prevented. The printing operation behavior when returning from the second cooling mode to the first cooling mode can be stabilized.

For comparison with the second modification example, in an image forming apparatus 10 having the same configuration as the second modification example, the internal temperature detection time was recorded at a sampling period of 1 second, that is, the fastest image forming period Tm (seconds). If the time is set to 1 second, which is less than the time required to print one sheet of paper (=1.5 seconds), the state transition between the first cooling mode and the second cooling mode will occur frequently. It has been found that irregular printing causes unpleasant sensations such as noise to the user.

Further, in the above embodiment and each modification example, the reference table shown in FIG. 6 is used, but a relational expression for calculating the development drive duty ratio may be used. For example, the storage unit 44 stores in advance a relational expression for calculating the developing drive duty ratio using the input data of the internal temperature Ti and the external temperature To. The control unit 46 calculates the developing drive duty ratio using the internal temperature Ti detected by the internal temperature detection unit 43, the external temperature To detected by the external temperature detection unit 49, and the relational expression. Also in this case, the developing drive duty ratio can be suitably calculated.

Further, in the above embodiment and each modification example, the drive section 47 shown in FIG. 5 includes the first clutch 47B and the second clutch 47F, but it may be configured without a clutch. In this case, the control unit 46 may stop the rotation of the first motor 47A and the second motor 47E during the print standby time (Tt).

<Third modification example>
In the embodiment described above, the control unit 46 causes the cooling fan 48 to rotate at the first rotation speed when the internal temperature Ti is equal to or higher than the fan operation threshold temperature T1 in the first cooling mode and the second cooling mode. However, it is not limited to this. During the print standby time (Tt) in the second cooling mode, the control unit 46 of the image forming apparatus 10 in the third modification sets the cooling fan 48 at a speed higher than the first rotation speed in the first cooling mode. Operate at a predetermined second rotational speed.

FIG. 10 is a flowchart showing cooling control of the developing device in the third modification. In the third modification, S121 to S125 shown in FIG. 10 are different from the flowchart shown in FIG. 8 of the above embodiment, so S121 to S125 will be explained.

As shown in FIG. 10, after the process in S111, the control unit 46 rotates the cooling fan 48 at the first rotation speed (S121). The control unit 46 causes the developing device 22 and the like to perform intermittent printing at the developing drive duty ratio specified in the process of S111 described above (S122). That is, during the printable time shown in FIG. 7, the control unit 46 rotates the cooling fan 48 at the first rotation speed, and causes the developing device 22 and the like to perform intermittent printing at the specified developing drive duty ratio. The control unit 46 determines whether or not the current time is the printable time (S123), and if it is determined that the current time is the printable time (S123 "Yes"), the process returns to S123. On the other hand, if the control unit 46 determines that it is not the printable time (S123 "No"), the control unit 46 rotates the cooling fan 48 at the second rotation speed (S124). That is, during the printing standby time shown in FIG. 7, the control unit 46 rotates the cooling fan 48 at the second rotation speed.

When the control unit 46 determines that it is the print standby time (S125 "Yes"), the process returns to S124 and continues the rotation of the cooling fan 48 at the second rotation speed. On the other hand, when the control unit 46 determines that it is not the print standby time (S125 "No"), that is, as shown in FIG. 7, when the print standby time ends, it determines whether the print job is finished (S114). . Since the processing after S114 is the same as in the above embodiment, the explanation here will be omitted.

According to the third modification, the control unit 46 controls the cooling fan 48 at a predetermined rotation speed higher than the first rotation speed in the first cooling mode during the printing standby time (Tt) in the second cooling mode. Since the printing apparatus is operated at the second rotational speed, the cooling effect during printing standby time (Tt) can be further improved.

Furthermore, by rotating at a predetermined second rotation speed that is higher than the first rotation speed, the cooling fan 48 can supply wind stronger than the above-mentioned breeze, thereby increasing the cooling effect.

Further, although a one-component developer such as one-component magnetic toner is illustrated as the developer stored in the developer storage section 31, a two-component developer made by mixing toner and carrier is used. The present invention can also be applied to.

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

Further, the configuration of the above embodiment described using FIGS. 1 to 10 is only an example of the present invention, and is not intended to limit the present invention to this configuration.

4 Photosensitive drum (image carrier)
10 Image forming device 22 Developing device 27 Developing roller 31 Developer storage section 32 Spiral feeder (stirring member)
41 Display section 42 Operation section 43 Inside temperature detection section 44 Storage section 46 Control section 47A First motor 47B First clutch 48 Cooling fan 49 Outside temperature detection section

Claims (7)

An image forming apparatus comprising a developing device, an external temperature detection section, and a control section,
The developing device includes:
a developing roller that applies a developer to the electrostatic latent image formed on the image carrier to develop the electrostatic latent image into a visible image;
a developer accommodating section that includes a stirring member that stirs the developer while conveying the developer along the developing roller, and supplies the developer to the developing roller;
an in-machine temperature detection section that is disposed on an outer wall surface of the developer accommodating section around a drive input section that drives the developing roller and the stirring member, and that detects the temperature of the outer wall surface of the developer accommodating section as an in-machine temperature; , comprising:
The external temperature detection unit detects the external temperature of the image forming apparatus,
The control unit performs cooling control by setting a first cooling mode in which continuous printing is possible when the internal temperature detected by the internal temperature detection unit is less than a first predetermined threshold temperature, and 1 If the period ta during which the internal temperature detected by the internal temperature detection unit is equal to or higher than the first threshold temperature when the cooling mode is set continues for longer than the fastest image forming cycle Tm (seconds) Maximum print number Pmax (sheets/min), fastest image forming cycle Tm = 60/Pmax) is determined by the machine internal temperature detected by the machine internal temperature detection section and the machine external temperature detected by the machine external temperature detection section. An image forming apparatus that performs cooling control by setting a second cooling mode to perform intermittent printing at a developing drive duty ratio. The control unit is configured to control a period tb during which the cabin temperature detected by the cabin temperature detection unit is less than a predetermined second threshold temperature that is lower than the first threshold temperature when the second cooling mode is set. The image forming apparatus according to claim 1, wherein the image forming apparatus performs cooling control by returning to the first cooling mode when the image forming apparatus continues for the fastest image forming period Tm (seconds) or more. In the second cooling mode, the control unit responds to a print request by setting a printable time t and a print standby time (Tt 3. The image forming apparatus according to claim 1, wherein the image forming apparatus performs intermittent printing with the developing drive duty ratio set as follows. The image forming apparatus according to claim 3, wherein the control unit drives the developing device during the printable time t, and does not drive the developing device during the print standby time (Tt). The developing device includes a motor and a clutch capable of switching between a transmission state in which the rotation of the motor is transmitted to the developing roller and the stirring member and a cutoff state in which the rotation is interrupted.
The control unit sets the clutch to a transmission state to drive the developing device and the stirring member during the printable time t, and sets the clutch to a disengaged state to drive the developing device during the printing standby time (Tt). The image forming apparatus according to claim 4, wherein the stirring member is not driven. a cooling fan that takes in air outside the image forming apparatus as cooling air and causes the taken in cooling air to flow along the surface of the developing roller;
During the printing standby time (Tt) in the second cooling mode, the control unit controls the cooling fan at a predetermined second rotational speed that is higher than the first rotational speed in the first cooling mode. The image forming apparatus according to any one of claims 3 to 5, wherein the image forming apparatus is operated. further comprising a storage unit that stores in advance a reference table showing the correspondence between the input data, which is the inside temperature and the outside temperature, and the developing drive duty ratio, which is the output data;
1 . The control unit specifies the developing drive duty ratio using the internal temperature detected by the internal temperature detection unit, the external temperature detected by the external temperature detection unit, and the reference table. The image forming apparatus according to claim 6.