JP2020160167A - Image formation apparatus - Google Patents

Abstract

To provide a structure which can further properly take the countermeasures against dew condensation in an apparatus body.SOLUTION: An environment sensor detects the temperature and humidity on the outside of an apparatus body. A scanner temperature sensor detects the temperature on the inside of the apparatus body. The absolute humidity obtained from the temperature and humidity detected by the environment sensor is defined as an external absolute humidity Ho, and the saturation absolute humidity obtained from the temperature detected by the scanner temperature sensor is defined as an internal saturation absolute humidity Hi. When the value obtained by subtracting Hi from Ho is larger than a first threshold α (YES in S302), the first control for stopping a cartridge fan 42a and a discharge path fan 42b (S305, S306) is executed. Then, when the value obtained by subtracting Hi from Ho is equal to or less than a second threshold β smaller than the first threshold α (YES in S310), the second control for driving the cartridge fan 42a and the discharge path fan 42b (S312, S313) is executed.SELECTED DRAWING: Figure 8

Description

The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile, and a multifunction device having a plurality of these functions.

The image forming apparatus is provided with a fan that takes in the outside air or exhausts the inside air in order to suppress the temperature rise inside. Further, a configuration has been proposed in which the fan is driven or stopped when there is a risk of dew condensation occurring inside the device by detecting the temperature and humidity outside the device and the temperature inside the device (patented). Document 1). In the configuration described in Patent Document 1, the fixing device is energized with the fan stopped during the first predetermined time, and then the fan is driven to drive the photoconductor and the like during the second predetermined time. I have to.

Japanese Unexamined Patent Publication No. 2003-98938

As described above, in the case of the configuration described in Patent Document 1, when it is determined that dew condensation may occur inside the apparatus, the fan is stopped for a predetermined first predetermined time, and then predetermined. The fan is driven during the second predetermined time. For this reason, the fan stop time is insufficient during the first predetermined time, and the subsequent fan drive causes more moist air than the internal air to flow in, causing dew condensation inside the apparatus main body. May not be sufficiently suppressed.

An object of the present invention is to provide a configuration capable of more appropriately taking measures against dew condensation in the main body of the apparatus.

The image forming apparatus of the present invention includes an apparatus main body, an image forming unit that is arranged inside the apparatus main body and forms a toner image on a recording material, and an external temperature / humidity detection that detects the temperature and humidity outside the apparatus main body. The function of at least one of the means, the in-flight temperature detecting means for detecting the temperature inside the device body, the intake of outside air into the inside of the device body, and the exhaustion of the air inside the device body to the outside. The absolute humidity obtained from the temperature and humidity detected by the outside temperature and humidity detecting means is the outside absolute humidity Ho, and the saturated absolute humidity obtained from the temperature detected by the inside temperature detecting means is inside the machine. When the saturated absolute humidity Hi is set and the value obtained by subtracting the Hi from the Ho is larger than the first threshold value α, the first control for stopping the blowing means is executed, and the first control is performed. A second control that drives the blower means when the value obtained by subtracting the Hi from the Ho is equal to or less than the second threshold β, which is smaller than the first threshold α, which is a control executed later. It is characterized by having a control means to execute.

According to the present invention, it is possible to more appropriately take measures against dew condensation inside the apparatus main body.

The schematic block sectional view of the image forming apparatus which concerns on embodiment. The schematic diagram which shows the air blowing path of the fan inside the apparatus main body which concerns on embodiment. A cross-sectional view of the path from the fixing end fan to the fixing device as viewed from above in FIG. 1, showing (a) a state in which the shutter is open and (b) a state in which the shutter is closed. The control block diagram of the image forming apparatus which concerns on embodiment. The flowchart of the control of the cartridge fan in the normal time which concerns on embodiment. The flowchart of control of the fixing end fan at the time of image formation which concerns on embodiment. The flowchart of the control of the power supply fan at the time of the 1st control which concerns on embodiment. The flowchart of the dew condensation countermeasure mode which concerns on embodiment. The graph which shows the change over time of the absolute humidity Ho outside the machine and the saturated absolute humidity Hi inside the machine according to the embodiment. The graph which shows the change with the lapse of time of the dew condensation counter Cnt which concerns on embodiment.

The embodiment will be described with reference to FIGS. 1 to 10. First, the schematic configuration of the image forming apparatus of this embodiment will be described with reference to FIG.

[Image forming device]
The image forming apparatus 100 of the present embodiment is an electrophotographic tandem full-color printer including four cartridges 7a, 7b, 7c, and 7d having photosensitive drums 1a, 1b, 1c, and 1d as image carriers, respectively. is there. The image forming apparatus 100 is arranged in the apparatus main body 100a (inside the apparatus main body), and has an image forming unit 101 that forms a toner image on a recording material. The image forming unit 101 includes cartridges 7a, 7b, 7c, 7d, a scanner unit 3, an intermediate transfer unit including an intermediate transfer belt 5, a fixing device 14, and the like.

The image forming apparatus 100 receives a toner image (image) in response to an image signal from a document reading device (not shown) connected to the apparatus main body 100a or a host device such as a personal computer communicably connected to the apparatus main body. Is formed on the recording material. Examples of the recording material include sheet materials such as paper, plastic film, and cloth. Further, the cartridges 7a, 7b, 7c, and 7d form a toner image of yellow, magenta, cyan, and black, respectively.

The four cartridges 7a, 7b, 7c, and 7d as a plurality of process units included in the image forming apparatus 100 have substantially the same configuration except that the developed colors are different. Therefore, the cartridge 7a will be described as a representative, and for other cartridges, the subscript "a" of the code attached to the configuration in the cartridge 7a will be replaced with b, c, and d, respectively, and the description will be omitted.

The cartridge 7a includes a drum unit 26a having an image carrier and a photosensitive drum 1a as a photoconductor for electrophotographic photography, and a developing unit 4a. The photosensitive drum 1a is rotationally driven clockwise (in the direction of arrow Q) in FIG. 1 by a driving member (not shown). Further, around the photosensitive drum 1a, a cleaning member 6a, a charging roller 2a, and a developing unit 4a are arranged in the order of their rotation directions.

The charging roller 2a uniformly charges the surface of the photosensitive drum 1a. After the surface of the photosensitive drum 1a is charged by the charging roller 2a, the surface of the photosensitive drum 1a is exposed to laser light as exposure light from the scanner unit (exposure means) 3 through the dustproof glasses 32a to 32d. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 1a. In this embodiment, the scanner unit 3 is arranged below the cartridges 7a to 7d.

Further, the scanner unit 3 has openings formed at positions where the photosensitive drums 1a to 1d can be irradiated, and the openings are covered with transparent dustproof glasses 32a to 32d, respectively. As a result, laser light can be irradiated from the inside of the scanner unit 3 to the photosensitive drums 1a to 1d through the dustproof glasses 32a to 32d, and foreign matter such as dust is suppressed from entering the inside of the unit. Further, the scanner unit 3 is provided with a scanner temperature sensor 41, and the irradiation timing of the laser beam is corrected so as to cancel the influence of the distortion of the housing of the scanner unit 3 caused by the temperature change. In the present embodiment, the temperature inside the apparatus main body 100a is detected by the scanner temperature sensor 41 as the in-machine temperature detecting means. Therefore, in the present embodiment, the scanner temperature sensor 41 is arranged closer to the scanner unit 3 than the environmental sensor 40 described later, and in the present embodiment, the scanner temperature sensor 41 is provided in the housing of the scanner unit 3.

The developing unit 4a is for supplying toner to the electrostatic latent image formed on the photosensitive drum 1a and developing the electrostatic latent image as a toner image. The developing unit 4a is provided with a developing roller 25a that comes into contact with the photosensitive drum 1a and supplies toner to the surface of the photosensitive drum 1a, and a supply roller 34a that comes into contact with the developing roller 25a and supplies toner to the developing roller 25a.

When forming an image on the recording material S, first, the electrostatic latent image formed on the surface of the photosensitive drum 1a by the scanner unit 3 is developed as a toner image by the developing unit 4a and transferred to the intermediate transfer belt 5.

The intermediate transfer belt 5 as the intermediate transfer body is stretched on the drive roller 10, the tension roller 11, and the like, and is driven in the direction of the arrow R in FIG. Further, primary transfer rollers 12a to 12d are arranged inside the intermediate transfer belt 5 so as to face each of the photosensitive drums 1a to 1d, and a transfer bias is applied by a power source (bias applying means) (not shown). It has a structure of For example, when a negatively charged toner is used, a positive electrode bias is applied to the primary transfer rollers 12a to 12d, so that the toner image is sequentially transferred onto the intermediate transfer belt 5. Further, a secondary transfer roller 18 as a secondary transfer member is arranged on the downstream side of the tension roller 11 with respect to the rotation direction of the intermediate transfer belt 5 so as to come into contact with the outer peripheral surface of the intermediate transfer belt 5. A secondary transfer unit 15 is formed between the surface and the secondary transfer roller 18.

The cleaning member 6a transfers the toner image formed on the photosensitive drum 1a onto the intermediate transfer belt 5, and then removes the toner remaining on the photosensitive drum 1a. The toner removed by the cleaning member 6a is collected in the removal toner chamber in the drum unit 26a.

The toner images on the photosensitive drums 1a to 1d are superimposed on the intermediate transfer belt 5 and primaryly transferred. Then, the toner images of the four colors are transferred to the secondary transfer unit 15 in a state of being overlapped on the intermediate transfer belt 5. In the secondary transfer unit 15, the toner image is secondarily transferred from the intermediate transfer belt 5 to the recording material S. The toner remaining on the intermediate transfer belt 5 after the secondary transfer to the recording material S is removed by the belt cleaning device 23, and the removed toner passes through a waste toner transport path (not shown) and is a waste toner collection container. Collected in (not shown).

On the other hand, in synchronization with the image forming operation described above, the recording material S is fed to the secondary transfer unit 15 by a transport mechanism including a feeding device 13 and a resist roller pair 17. The feeding device 13 includes a feeding cassette 24 for storing a plurality of recording materials S, a feeding roller 8 for feeding the recording material S, and a transport roller pair 16 for transporting the fed recording material S. are doing.

The feeding cassette 24 is detachably configured from the apparatus main body 100a of the image forming apparatus 100. The user pulls out the feeding cassette 24, removes it from the apparatus main body 100a, sets the recording material S, and inserts the recording material S into the apparatus main body to complete the replenishment of the recording material S. Of the recording materials S stored in the feeding cassette 24, the feeding roller 8 is pressed against the recording material S located at the highest position, and is peeled off one by one by the separation pad 9 as the feeding roller 8 rotates. (Friction piece peeling method), the recording material S is conveyed.

Then, the recording material S conveyed from the feeding device 13 is conveyed to the secondary transfer unit 15 by the resist roller pair 17. In the secondary transfer unit 15, by applying a positive electrode bias to the secondary transfer roller 18, the four-color toner image on the intermediate transfer belt 5 can be secondarily transferred to the transferred recording material S. It is possible.

Then, the recording material S supplied from the secondary transfer unit 15 is further conveyed to the fixing device 14. The fixing device 14 has a fixing belt 14a, a pressure roller 14b, and a heater 14c, as shown in FIG. 1 and FIGS. 3A and 3B described later. The fixing belt 14a as the fixing rotating body is a thin-walled hollow endless belt. The pressure roller 14b as a nip forming member is pressed against the fixing belt 14a to form a nip portion N that sandwiches and conveys the recording material S with the fixing belt 14a. The heater 14c as a heating portion is arranged on the inner peripheral surface of the fixing belt 14a so as to hold the fixing belt 14a between the pressing roller 14b and rub it, and heat the fixing belt 14a. In such a fixing device 14, heat and pressure are applied to the toner image supported on the recording material S at the nip portion N to fix the toner image on the recording material S.

After that, the recording material S on which the toner image is fixed is discharged to the discharge tray 20 by the discharge roller pair 19 through the discharge path 19a. The discharge path 19a as a transfer path conveys the recording material S between the fixing device 14 and the discharge roller pair 19 as the discharge means.

[Fan configuration and ventilation path]
Next, the configuration of a plurality of fans and the ventilation path included in the image forming apparatus 100 of the present embodiment will be described with reference to FIGS. 1 to 4. The present embodiment includes a cartridge fan 42a, a discharge path fan 42b, a fixing end fan 42c, and a power supply fan 42d. The front side of the paper surface of FIGS. 1 and 2 is the front surface of the image forming apparatus 100, and the back side of the paper surface is the back surface of the image forming apparatus 100.

In the present embodiment, the cartridge fan 42a and the exhaust passage fan 42b are blown air having at least one of the functions of taking in the outside air into the device main body 100a and exhausting the air inside the device main body 100a to the outside. Corresponds to means. The cartridge fan 42a and the exhaust passage fan 42b are intake fans that take in outside air into the apparatus main body 100a, but at least one fan may be an exhaust fan that exhausts the air inside the apparatus main body 100a to the outside.

[Cartridge fan]
The cartridge fan 42a as the first air blower is arranged in the vicinity of the opening 71 provided on one side surface (left side surface of FIGS. 1 and 2) of the apparatus main body 100a of the image forming apparatus 100, and is located outside the apparatus main body 100a. Air is taken into the inside to generate an air flow T1. The opening 71 communicates between the inside and the outside of the apparatus main body 100a, and the cartridge fan 42a is arranged inside the apparatus main body 100a so as to face the opening 71. The cartridge fan 42a is for cooling the cartridges 7a to 7d including the developing units 4a to 4d that mainly handle toner. In the present embodiment, two cartridge fans 42a are arranged on one side surface of the apparatus main body 100a, but one cartridge fan 42a may be used.

When images are formed, the cartridges 7a to 7d gradually rise in temperature due to the heat generated from the fixing device 14 and electrical components (not shown) inside the device body 100a, or the effect of self-heating due to driving. To go. When the temperature rises significantly, the toner melts due to heat, which may lead to image defects and drive defects. Therefore, in the present embodiment, the cartridge fan 42a sucks outside air into the cartridges 7a to 7d as a plurality of process units to cool the cartridges 7a to 7d.

Therefore, in the present embodiment, as shown in FIG. 2, the duct 61 connected to the cartridge fan 42a is arranged above the cartridges 7a to 7d. Then, the outside air is sent to the cartridges 7a to 7d from the plurality of openings 61a provided in the duct 61.

The airflow taken in from the cartridge fan 42a flows between the adjacent cartridges 7a to 7d through the opening 61a of the duct 61 and reaches the surface of the scanner unit 3 (the surface on the cartridge 7a to 7d side). Then, it flows on the dustproof glasses 32a to 32d on the surface of the scanner unit 3. Further, the airflow leaking from the gap of the duct 61 also flows on the surfaces of the dustproof glasses 32a to 32d on the surface of the scanner unit 3. That is, the cartridge fan 42a forms an air flow that passes through the surfaces of the dustproof glasses 32a to 32d, which are the emission surfaces of the laser light (exposure light) of the scanner unit 3. Therefore, by flowing the air flow through the scanner unit 3 in this way, the surfaces of the dustproof glasses 32a to 32d can be dried to prevent dew condensation, and even if dew condensation occurs, the dew condensation can be dried at an early stage.

Further, in the case of the present embodiment, as shown in FIG. 1, an environment sensor 40 as an external temperature / humidity detecting means is arranged at a position facing the opening 71 in the device main body 100a (inside the device main body). .. The environment sensor 40 is arranged near the opening 71 and detects the temperature and humidity outside the device main body 100a. As shown in FIG. 4, the environment sensor 40 is connected to the control unit 50 as a control means, and the control unit 50 is based on the temperature detected by the environment sensor 40 and the amount of temperature rise predicted from the image forming operation. The temperature of the cartridges 7a to 7d is predicted. The cartridge fan 42a is usually driven and stopped based on the cartridge predicted temperature predicted in this way, which will be described later.

[Discharge channel fan]
As shown in FIGS. 1 and 2, the exhaust passage fan 42b as the second air blower is provided in the vicinity of the opening 72 provided in the front surface of the device main body 100a of the image forming apparatus 100, and is provided outside the device main body 100a. Air is taken into the inside to generate an air flow T2. The opening 72 communicates between the inside and the outside of the device main body 100a, and the discharge path fan 42b is arranged inside the device main body 100a so as to face the opening 72. The device main body 100a is provided with a door (not shown) openable and closable on the front side, and the cartridges 7a to 7d can be replaced by opening the door. In the present embodiment, the discharge path fan 42b is provided at a position corresponding to the door of the apparatus main body 100a.

Such a discharge path fan 42b is mainly for exhausting the water vapor generated in the fixing device 14 to the outside of the device main body 100a. That is, when the recording material S passes through the fixing device 14, the water contained in the recording material S evaporates due to the heat of the fixing device 14, and water vapor is generated. When this water vapor is not exhausted, water droplets are generated in parts such as the discharge passage 19a and the discharge roller pair 19 arranged above the fixing device 14, which leads to poor transport of the recording material S and deterioration of image quality due to water droplet adhesion. There is. Therefore, the exhaust passage fan 42b is designed to take in the outside air toward the exhaust passage 19a.

In the case of the present embodiment, as shown in FIG. 2, the apparatus main body 100a is provided with a duct 63 connected to the discharge path fan 42b. The duct 63 extends from the discharge path fan 42b above the device main body 100a, and is arranged so that the air taken in from the discharge path fan 42b reaches the discharge path 19a and the discharge roller pair 19. An opening 64 is formed at the upper end of the duct 63, and the airflow sent from the discharge passage fan 42b flows from the opening 64 through the discharge passage 19a and the vicinity of the discharge roller pair 19. Then, the airflow from the opening 64 is exhausted to the outside through the discharge opening where the recording material S is discharged to the discharge roller pair 19 together with the water vapor above the fixing device 14 generated by the fixing device 14 as described above. ..

Further, the discharge path fan 42b is arranged in the vicinity of the cartridge 7d farthest from the cartridge fan 42a among the plurality of cartridges 7a to 7d. Therefore, the exhaust passage fan 42b takes in air in the vicinity of the cartridge 7d in addition to the intake of air from the outside, and generates an air flow T2'as shown in FIG. As described above, the airflow taken in from the cartridge fan 42a flows on the surfaces of the dustproof glasses 32a to 32d of the scanner unit 3, but the airflow is unlikely to be generated in the cartridge 7d farthest from the cartridge fan 42a, or even if it is generated. There are few. Therefore, the dustproof glass 32d facing the cartridge 7d may be insufficiently dried. Therefore, in the present embodiment, by sucking the airflow in the vicinity of the cartridge 7d from the discharge path fan 42b, it is easy to form the airflow on the surface of the dustproof glass 32d, and the surface of the dustproof glass 32d is less likely to condense. ing. That is, the discharge path fan 42b forms an air flow that passes through the surface of the dustproof glass 32d, which is the emission surface of the laser beam (exposure light) of the scanner unit 3.

[Fixed end fan]
As shown in FIG. 1, the fixing end fan 42c as the fixing device air blowing means is arranged in the vicinity of the opening 73 provided on one side surface of the device main body 100a of the image forming device 100, and is located outside the device main body 100a. Air is taken into the inside to generate an air flow T3. The opening 73 communicates between the inside and the outside of the apparatus main body 100a, and the fixing end fan 42c is arranged inside the apparatus main body 100a so as to face the opening 73.

When the width of the recording material S (the size in the direction orthogonal to the transport direction) is narrow, the fixing end fan 42c does not pass through the recording material S when the recording material S passes through the fixing device 14. It is for cooling the fixing belt 14a of the region. That is, the fixing end fan 42c can supply air to both ends of the fixing belt 14a in the width direction intersecting the conveying direction of the recording material S at the time of image formation.

That is, in the fixing belt 14a, the heat in the passing region through which the recording material S passes is taken away by the recording material S, whereas the heat in the non-passing region is not easily taken away by the fixing belt 14a. If the temperature of the non-passing region rises significantly, it may lead to image defects, transfer defects of the recording material S, and damage to parts. Therefore, the fixing end fan 42c sucks air to suppress the temperature rise in this non-passing region.

Therefore, in the present embodiment, as shown in FIG. 1, the duct 62 connected to the fixing end fan 42c is arranged above the cartridges 7a to 7d. As shown in FIGS. 3A and 3B, the duct 62 is branched into a first duct portion 62a and a second duct portion 62b, and the first duct portion 62a and the second duct portion 62b are fixed belts 14a. It is designed to face both ends in the width direction of.

Further, between the fixing belt 14a and the first duct portion 62a and the second duct portion 62b, a shutter 43 is arranged so as to open and close the openings of the first duct portion 62a and the second duct portion 62b, respectively. There is. FIG. 3A shows a state in which the shutter 43 opens the openings of the first duct portion 62a and the second duct portion 62b, and FIG. 3B shows a state in which the shutter 43 opens the first duct portion 62a and the second duct. A state in which the opening of the portion 62b is shielded is shown. The shutter 43 can change the opening widths of the first duct portion 62a and the second duct portion 62b according to the size of the recording material passing through the nip portion N, and the airflow T3 is not recorded from the fixing end fan 42c. It is controlled by the control unit 50 (FIG. 4) so as to correspond to the passing region.

Further, in the present embodiment, the fixing center temperature sensor 44a and the fixing end temperature sensor 44b are arranged so as to come into contact with the heater 14c at the center and the end in the rotation axis direction (width direction) of the fixing belt 14a. The fixing central temperature sensor 44a detects the heater temperature in the passing region, and at the time of image formation, the control unit 50 controls the heater temperature to 200 ° C. in order to fix the toner image on the recording material S. The fixing end temperature sensor 44b as a heating part temperature detecting means can detect the heater temperature in the non-passing region, and as will be described later, the detection result is used for controlling the fixing end fan 42c.

The duct 62 through which the airflow T3 from the fixing end fan 42c flows and the duct 61 through which the airflow T1 from the cartridge fan 42a flows are arranged side by side in the front-rear direction inside the apparatus main body 100a. However, the arrangement of these ducts 61 and 62 may be arranged in the vertical direction of FIG. 1, and may be appropriately set based on the shape and size of the device main body 100a, the cartridges 7a to 7d, the arrangement of the fixing device 14, and the like. It is possible.

[Power fan]
As shown in FIGS. 1 and 2, the power supply fan 42d as the power supply blowing means is connected to the device main body 100a from the opening 74 provided on the other side surface (right side surface of FIGS. The air inside the above is exhausted to the outside to generate an air flow T4. The opening 74 communicates the inside and the outside of the device main body 100a, and the power supply fan 42d is arranged inside the device main body 100a so as to face the opening 74. The power supply fan 42d is mainly for cooling the power supply unit 70 (FIG. 2), which is a low-voltage power supply. The power supply unit 70 can supply, for example, the electric power supplied from an external commercial power source to each part of the apparatus main body 100a. In the case of the present embodiment, the power supply fan 42d can be switched between low-speed drive and high-speed drive in which the air volume is larger than that of low-speed drive.

Further, in the present embodiment, the cartridge fan 42a, the discharge path fan 42b, and the fixing end fan 42c have an intake configuration, and the inside of the device tends to have a positive pressure with respect to the outside. Therefore, the power supply fan 42d having an exhaust configuration also has a function of exhausting the air. Further, the power supply unit 70 is provided with a power supply temperature sensor 45 as a power supply temperature detecting means capable of detecting the temperature of the power supply unit 70, and the power supply fan 42d is provided with the power supply temperature sensor 45 at the time of the first control described later. It is controlled based on the temperature detected by.

[Control unit]
The control configuration of the image forming apparatus 100 of the present embodiment will be briefly described with reference to FIG. The control unit 50 controls the entire image forming apparatus 100. Such a control unit 50 has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU controls each part while reading a program corresponding to the control procedure stored in the ROM. In addition, work data and input data are stored in the RAM, and the CPU controls by referring to the data stored in the RAM based on the above-mentioned program or the like.

Further, various sensors such as an environment sensor 40, a scanner temperature sensor 41, a fixing center temperature sensor 44a, a fixing end temperature sensor 44b, and a power supply temperature sensor 45 are connected to the control unit 50. Further, each part such as a fixing device 14, a shutter 43, a cartridge fan 42a, a discharge path fan 42b, a fixing end fan 42c, and a power supply fan 42d is connected to the control unit 50. Each part of the image forming apparatus 100 is controlled by the control unit 50 based on the detection signals of each of these sensors.

For example, the fixing device 14 (specifically, the heater 14c) is energized and controlled based on the detection result of the fixing center temperature sensor 44a. The opening / closing position of the shutter 43 (specifically, a drive source such as a motor for driving the shutter 43) is controlled according to the size of the recording material passing through the nip portion N of the fixing device 14.

Further, the cartridge fan 42a and the discharge path fan 42b are controlled based on the detection results of the environment sensor 40 and the scanner temperature sensor 41, as will be described later. Further, the fixing end fan 42c is controlled based on the detection result of the fixing end temperature sensor 44b, and the power supply fan 42d is controlled based on the power supply temperature sensor 45. The fixing end fan 42c and the power supply fan 42d may be driven or stopped regardless of the detection results of these sensors.

[Normal fan control]
Next, the operation of each fan in a normal state will be described with reference to FIGS. 5 and 6 and Table 1. The normal time is a time when the first control and the second control (condensation countermeasure mode) described later are not executed. In addition, Table 1 shows the operation of each fan in the normal state of each fan separately in the standby state and the image formation time.

The standby state is a state in which the power of the image forming apparatus 100 is turned on, various preparatory operations are completed, and the heater temperature of the fixing apparatus 14 is maintained at a temperature lower than that at the time of image forming. Specifically, during standby, the heater 14c of the fixing device 14 is energized to enter the fixing standby temperature control state. During the fixing standby temperature control, the fixing belt 14a and the pressurizing roller 14b are not driven, and the temperature is controlled at a lower temperature than during image formation by the fixing central temperature sensor 44a. In this embodiment, the temperature was set to 150 ° C. In such a standby state, the image forming operation can be started immediately after the image forming job is input. At the time of image formation, the image formation job is being executed.

Here, the image formation job is a period from the start of image formation to the completion of image formation based on the print signal (image formation signal) that forms an image on the recording material. That is, the image formation job performs a series of operations of a pre-operation (forward rotation) performed before the image formation operation, an image formation operation, and a post-operation (rear rotation) performed after the image formation operation by inputting the image formation signal. The period.

Further, the image forming apparatus 100 can shift to a sleep state in which the power consumption is lower than that in the standby state when a state in which the operator does not operate or the image forming operation is not performed has elapsed for a predetermined time or more. During sleep, for example, the energization of the fixing device 14 is stopped, and the driving of each fan is also stopped. The sleep state may have lower power consumption than the standby state, and the function to be stopped may differ depending on the device or mode.

First, as shown in Table 1, the operation of the cartridge fan 42a during normal operation is controlled according to the flow shown in FIG. 5 during both standby and image formation. That is, as shown in FIG. 5, when the control of the cartridge fan 42a is started (S101), the control unit 50 predicts the temperature detected by the environment sensor 40 and the temperature rise predicted from the image forming operation as described above. Calculate the estimated cartridge temperature from the quantity. Then, the control unit 50 determines whether or not the cartridge predicted temperature is equal to or higher than a predetermined temperature (35 ° C. in the present embodiment) (S102). Then, when the predicted cartridge temperature is 35 ° C. or higher (YES in S102), the cartridge fan 42a is driven (S103). On the other hand, when the predicted cartridge temperature is less than 35 ° C. (NO in S102), the cartridge fan 42a is stopped (S104).

Next, as shown in Table 1, the discharge path fan 42b is stopped during normal operation during standby and driven during image formation. The discharge path fan 42b is stopped during standby because the recording material does not pass through the nip portion N and water vapor is not generated. Therefore, in order to suppress power consumption, the discharge path fan 42b is stopped during standby in the normal operation. Even at this time, the discharge path fan 42b may be driven. On the other hand, at the time of image formation, the recording material may pass through the nip portion N and water vapor may be generated, so that the discharge path fan 42b is driven.

Next, as shown in Table 1, the fixing end fan 42c is controlled during normal operation according to the flow shown in FIG. 6 during standby operation and during image formation. The flow of FIG. 6 will be described. First, when the control of the fixing end fan 42c is started (S201), the control unit 50 acquires the width size of the recording material S (S202). The width size of the recording material S is based on, for example, information input by the operator by an input unit (not shown). The control unit 50 controls a drive source (not shown) such as a motor that drives the shutter 43 according to the acquired width of the recording material S, and opens the shutter 43 so as to open the non-passing region of the recording material S. Operate (S203).

Next, the control unit 50 determines whether or not the temperature detected by the fixing end temperature sensor 44b is equal to or higher than the predetermined heater temperature (220 ° C. in the present embodiment) (S204). Then, when the detection temperature of the fixing end temperature sensor 44 is 220 ° C. or higher (YES in S204), the fixing end fan 42c is driven (S205). On the other hand, when the detection temperature is less than 220 ° C. (NO in S204), the fixing end fan 42c is stopped (S206).

Next, the control unit 50 determines whether or not the image forming job is completed (S207), and if the image forming job is not completed (NO in S207), returns to S202. On the other hand, when the image forming job is completed (YES in S207), the control unit 50 closes the shutter 43 (S208), stops the fixing end fan 42c (S209), and ends the control of the fixing end fan 42c. (S210).

Next, as shown in Table 1, the power supply fan 42d is driven at low speed during normal operation and at high speed during image formation. That is, during standby of the image forming apparatus 100, and particularly during image forming, the electric components of the power supply unit 70 generate heat and raise the temperature. Therefore, the power supply unit 70 is cooled by driving the power supply fan 42d at a low speed during standby when the amount of temperature rise is low and driving at high speed during image formation when the amount of temperature rise is high.

[Condensation countermeasure mode]
Next, the dew condensation countermeasure mode according to this embodiment will be described with reference to FIGS. 6 to 10 and Tables 2 and 3. First, the image forming apparatus is installed and used in various environments. This includes the case where the room is rapidly heated and humidified by a heater or a humidifier the next morning in a low temperature environment at night. In such an environment, various rollers such as photosensitive drums and developing rollers inside the main body of the device, glass parts of laser scanners, and other parts that have a large heat capacity and are difficult to heat cannot keep up with the rise in environmental temperature and remain at a low temperature for several hours. May be. At this time, if the fan is kept operating constantly, warm and moist air outside the device flows into the vicinity of the low temperature component inside, and dew condensation occurs on the surface of the component.

Therefore, it is conceivable to stop the fan when the environment is such that dew condensation is likely to occur. However, if the environmental temperature and humidity fluctuate more than expected, dew condensation may occur even with a small amount of air flowing into the main body of the device through openings or gaps in the device. Then, once dew condensation occurs, it takes time to evaporate the water droplets generated by the dew condensation even when the internal temperature warms up. Therefore, in the present embodiment, the following dew condensation countermeasure mode can be executed.

In the present embodiment, the dew condensation countermeasure mode has a first control and a second control, and executes the first control and the second control by the following parameters. First, the absolute humidity obtained from the temperature and humidity detected by the environment sensor 40 is defined as the outside absolute humidity Ho, and the saturated absolute humidity obtained from the temperature detected by the scanner temperature sensor 41 is defined as the in-flight saturated absolute humidity Hi. Ho and Hi are calculated by the control unit 50. In the present embodiment, the absolute humidity is the absolute humidity by weight, and the amount of saturated water vapor is calculated by the Sunday formula. However, the absolute humidity by weight may be the absolute humidity by volume corresponding to the absolute humidity, and the saturated water vapor pressure is calculated. Other approximation formulas may be used.

Then, the control unit 50 executes the first control for stopping the cartridge fan 42a and the discharge path fan 42b when the value obtained by subtracting Hi from Ho is larger than the first threshold value α (Ho—Hi> α). To do. Further, when the value obtained by subtracting Hi from Ho is equal to or less than the second threshold value β, which is smaller than the first threshold value α (Ho−Hi ≦ β), the control unit 50 sets the cartridge fan 42a and the discharge path fan 42b. Perform a second control to drive. The second control is the control executed after the first control.

That is, the control switching is determined from the external absolute humidity Ho calculated from the temperature and humidity outside the device detected by the environment sensor 40 and the internal saturated absolute humidity Hi calculated from the temperature inside the device detected by the scanner temperature sensor 41. .. Then, in the first control, the fan of the image forming apparatus 100 is stopped as much as possible to suppress the occurrence of dew condensation due to the internal inflow of warm and moist air outside the apparatus main body 100a. On the other hand, in the second control, the fan included in the image forming apparatus 100 is driven as much as possible, and the generated dew condensation is blown by an air flow to dry the image forming apparatus 100 at an early stage.

Further, in the present embodiment, the first threshold value α = 0 is set. However, the value of α may be arbitrarily set depending on the variation between the environment sensor 40 and the scanner temperature sensor 41 and the necessity of measures against dew condensation in the target environment of the image forming apparatus 100. If the value of α is set small, the first control can be easily executed and the effect of dew condensation countermeasures becomes higher, but it becomes difficult to suppress the temperature rise inside the device main body 100a, and the exhaust performance of water vapor above the fixing device 14 Decreases. On the contrary, if the value of α is large, it becomes difficult to execute the first control and the effect of the dew condensation countermeasure is reduced, but it becomes easy to suppress the temperature rise inside the device main body 100a, and the exhaust of water vapor above the fixing device 14 is performed. Performance improves. From the above, it is preferable that the first threshold value α is set so as to satisfy -1 [g / kg] ≦ α ≦ 1 [g / kg].

Further, in the present embodiment, the second threshold value β = -1. However, if β is a value smaller than α (β <α), the value of β may be arbitrarily set in the same manner as the value of α. If the value of β is large, the second control can be easily executed, the time until dew condensation recovery is shortened, the temperature rise inside the device main body 100a can be easily suppressed, and the exhaust performance of water vapor above the fixing device 14 can be improved. Improve. However, if the inside of the device main body 100a is not sufficiently warmed, dew condensation may temporarily occur inside the device main body 100a. On the contrary, if the value of β is set small, it becomes difficult to execute the second control, it takes time to recover the dew condensation, it becomes difficult to suppress the temperature rise inside the device main body 100a, and the exhaust of water vapor above the fixing device 14 becomes difficult. Performance is reduced. However, the effect of suppressing dew condensation is enhanced. From the above, it is preferable that the second threshold value β is set so as to satisfy −5 [g / kg] ≦ β <1 [g / kg].

Further, in the present embodiment, a dew condensation counter Cnt is used in order to grasp how much water droplets are generated inside the apparatus main body 100a due to dew condensation. The dew condensation counter Cnt (count value Cnt) is calculated by subtracting the in-flight saturation absolute humidity Hi from the outside absolute humidity Ho and adding it every first hour (every 10 seconds in this embodiment). The first time can be set as appropriate.

The dew condensation counter Cnt is set to 0 at the start of execution of the first control. Then, after the execution of the second control is started, when the state in which the dew condensation counter Cnt is 0 or less continues for the second time (continues for 10 minutes in the present embodiment), the second control is terminated. There is. The dew condensation counter Cnt is not calculated except when the dew condensation countermeasure mode is executed. Further, the dew condensation counter Cnt may be set to 0 so as not to be less than 0, that is, when it becomes a negative value. In this case, since the dew condensation counter Cnt is 0 at the end of the second control, it is 0 at the next start of execution of the first control. The second time can also be set as appropriate.

Further, the fixing device 14 as a heating means is energized in both the first control and the second control, and heats the inside of the device main body 100a. That is, the fixing device 14 is temperature-controlled so as to be the temperature at the time of standby at the time of standby and the temperature at the time of image formation at the time of image formation. Therefore, particularly in the first control, the temperature inside the apparatus main body 100a gradually rises due to the heat of the fixing apparatus 14.

Under the first control condition, the temperature of the outside is often higher than that of the inside, so that when the fan is driven, the warm air from the outside enters the inside and the temperature inside the apparatus main body 100a is likely to rise. However, as described above, in the first control, since the cartridge fan 42a and the discharge path fan 42b are stopped, it is difficult for the outside air to enter the inside. Therefore, in the first control, the temperature inside the device main body 100a is gradually increased by raising the temperature of each device inside the device main body 100a and gradually transmitting the outside air temperature through the housing or the like. become.

When the temperature inside the apparatus main body 100a rises, the saturated absolute humidity Hi inside the machine also rises, the difference from the absolute humidity Ho outside the machine becomes smaller, and the Hi becomes larger than Ho. In such a state, dew condensation is unlikely to occur inside the apparatus main body 100a even if outside air enters. Therefore, in particular, in the first control, it is preferable to raise the temperature inside the device main body 100a by the heat of the fixing device 14.

On the other hand, even in the second control, when the temperature inside the apparatus main body 100a rises, the air inside can be dried, and the drier air can be applied to the dew condensation. Therefore, even in the second control, it is preferable to raise the temperature inside the apparatus main body 100a by the heat of the fixing apparatus 14.

However, the heating of the inside of the device main body 100a by the fixing device 14 may be performed in at least one of the first control and the second control. That is, in either the first control or the second control, the energization of the fixing device 14 may be stopped, for example, during standby. However, from the above viewpoint, it is preferable that the inside of the apparatus main body 100a is heated by the fixing apparatus 14 at least in the first control.

As described above, the cartridge fan 42a and the discharge path fan 42b are stopped during the first control and driven during the second control. On the other hand, the fixing end fan 42c was detected by the fixing end temperature sensor 44b at the time of image formation regardless of whether or not the first control and the second control were executed for the purpose of protecting the fixing device 14. It drives and stops based on temperature (see FIG. 6). Further, in order to protect the power supply board and the like, the power supply fan 42d is driven and stopped based on the temperature detected by the power supply temperature sensor 45 during the first control (see FIG. 7 described later), and the second power supply fan 42d is driven and stopped. Drives during execution of control. Hereinafter, the operation of each fan during the first control and the second control will be described.

[Fan control during the first control]
Next, the operation of each fan during the first control will be described with reference to FIGS. 6 and 7 and Table 2. Table 2 shows the operation of each fan during the first control of each fan separately during standby and image formation.

First, as shown in Table 2, the cartridge fan 42a and the discharge path fan 42b are stopped during the first control operation during both standby and image formation. This makes it difficult for warm and moist air outside the device body 100a to flow into the inside. In the first control, the case where the cartridge fan 42a and the discharge path fan 42b are stopped includes the case where the cartridge fan 42a and the discharge path fan 42b are stopped from the drive state and the case where the stopped state is continued as it is. ..

Next, as shown in Table 2, the fixing end fan 42c is controlled according to the flow shown in FIG. 6 when the first control operation is stopped during standby and when the image is formed. That is, during standby, the temperature of the fixing device 14 is controlled at a lower temperature than during image formation, and the recording material does not pass through the nip portion N. Therefore, even if the fixing end fan 42c is not driven, the temperature of both ends of the fixing belt 14a does not rise excessively. Therefore, at the time of standby, similarly to the cartridge fan 42a and the discharge path fan 42b, the fixing end fan 42c is stopped to prevent the warm and moist air outside the apparatus main body 100a from flowing into the inside.

On the other hand, at the time of image formation, the fixing end fan 42c is controlled according to the flow of FIG. 6 described above in order to prevent the temperature of the non-passing region of the fixing device 14 from rising significantly. That is, in order to suppress image defects due to the temperature rise in the non-passing region, transfer defects of the recording material S, and damage to parts, the fixing end fan 42c may be driven even during the first control.

Next, as shown in Table 2, the operation of the power supply fan 42d during the first control is controlled according to the flow of FIG. 7 during both the standby mode and the image formation. The flow of FIG. 7 will be described. First, when the control of the power supply fan 42d is started (S401), the control unit 50 determines whether or not the temperature detected by the power supply temperature sensor 45 is equal to or higher than the predetermined power supply temperature (50 ° C. in the present embodiment). Judgment (S402). Then, when the detection temperature of the power supply temperature sensor 45 is 50 ° C. or higher (YES in S402), the power supply fan 42d is driven at high speed (S403). On the other hand, when the detection temperature is less than 50 ° C. (NO in S402), the power supply fan 42d is stopped (S404).

That is, during the standby in the first control, the cartridge fan 42a, the discharge path fan 42b, and the fixing end fan 42c are stopped, and the temperature inside the apparatus main body 100a tends to rise. Further, the power supply unit 70 is energized even during standby. Therefore, the temperature of the power supply unit 70 may rise and the electric components such as the substrate may be damaged. Further, at the time of image formation in the first control, although the fixing end fan 42c is driven, the temperature of the power supply unit 70 may rise and the electric components may be damaged.

On the other hand, at the time of the first control, it is desirable to stop the fan as much as possible so that the outside air does not flow into the inside. Therefore, the temperature of the power supply unit 70 is detected by the power supply temperature sensor 45, and the power supply fan 42d is appropriately driven so as not to damage the substrate or the like. When the temperature of the power supply unit 70 is low, the drive of the power supply fan 42d is stopped as much as possible to suppress the inflow of external air.

[Fan control during the second control]
Next, the operation of each fan during the second control will be described with reference to FIGS. 6 and 3. Note that Table 3 shows the operation of each fan during the second control of each fan separately during standby and image formation.

First, as shown in Table 3, the cartridge fan 42a and the discharge path fan 42b are driven during the second control operation during both standby and image formation. As a result, an air flow is generated inside the apparatus main body 100a, and even if dew condensation occurs, it is dried at an early stage.

Next, as shown in Table 3, the fixing end fan 42c is driven during the second control operation during standby, and is controlled according to the flow shown in FIG. 6 during image formation. That is, since the fixing device 14 does not perform the fixing operation during standby, the fixing end fan 42c is driven as much as possible without performing control based on the detection temperature of the fixing end temperature sensor 44b as shown in FIG. I try to do it. Then, an air flow is generated inside the apparatus main body 100a so that the dew condensation is dried at an early stage. On the other hand, at the time of image formation, the fixing end fan 42c is controlled according to the flow of FIG. 6 described above in order to protect the device and the like, as in the case of the first control.

Next, as shown in Table 3, the power supply fan 42d is driven at high speed during the second control operation during both standby and image formation. That is, at the time of the second control, in order to dry the dew condensation, it is desired to drive the fan as much as possible, so that the power supply fan 42d is driven at high speed both in the standby state and in the image forming state.

[Example of flow in anti-condensation mode]
Next, an example of the flow of the dew condensation countermeasure mode of the present embodiment will be described with reference to FIG. First, when the image forming apparatus 100 returns from the sleep state (S301) when the power of the image forming apparatus 100 is turned on or an image forming job is input, the Ho-Hi of the control unit 50 is set. It is determined whether or not it is larger than the first threshold value α (S302). Then, when Ho-Hi is larger than α (YES in S302), the control unit 50 executes the first control, sets the dew condensation counter Cnt to 0 (S303), and the image forming apparatus 100 is forming an image. Whether or not it is determined (S304).

Then, when the image is being formed (YES in S304), the cartridge fan 42a and the discharge path fan 42b are stopped according to the operations shown in Table 2 (S305). The fixing end fan 42c and the power supply fan 42d also perform the operations shown in Table 2. Further, even when the image is not being formed but is in standby mode (NO in S304), the cartridge fan 42a and the discharge path fan 42b are stopped according to the operations shown in Table 2 (S306). The fixing end fan 42c and the power supply fan 42d also perform the operations shown in Table 2. Further, the fixing device 14 is in a state of fixing standby temperature control (S307).

Next, the dew condensation counter Cnt is added (S308), and the first time (10 seconds in this embodiment) is waited (S309). Then, the control unit 50 determines whether or not Ho-Hi is β or less (S310). When Ho-Hi is larger than β (NO in S310), the process returns to S304 and the first control is continued. In the present embodiment, S304 to S310 are the first controls.

When Ho-Hi becomes β or less in S310 (YES in S310), the first control is terminated, the second control is executed, and it is determined whether or not the image forming apparatus 100 is in the process of forming an image. (S311). Then, when the image is being formed (YES in S311), the cartridge fan 42a and the discharge path fan 42b are driven according to the operations shown in Table 3 (S312). The fixing end fan 42c and the power supply fan 42d also perform the operations shown in Table 3.

Further, even when the image is not being formed but is in standby mode (NO in S311), the cartridge fan 42a and the discharge path fan 42b are driven according to the operations shown in Table 3 (S313). The fixing end fan 42c and the power supply fan 42d also perform the operations shown in Table 3. Further, the fixing device 14 is in a state of fixing standby temperature control (S314).

Next, as in the first control, the dew condensation counter Cnt is added (S315), and the first time (10 seconds in this embodiment) is waited (S316). Then, the control unit 50 determines whether or not the state in which the dew condensation counter Cnt is 0 or less continues for the second time (10 minutes in the present embodiment) (S317). If the dew condensation counter Cnt is larger than 0, or even if it is 0 but not continued for 10 minutes (NO in S317), the process returns to S311 and the second control is continued. In the present embodiment, S311 to S317 are the second controls.

On the other hand, when the state where the dew condensation counter Cnt is 0 or less continues for 10 minutes (YES in S317), it is determined that the water droplets due to the dew condensation inside the apparatus main body 100a have been eliminated, and the first and second controls are performed. The dew condensation countermeasure mode is terminated (S318).

In the above-mentioned flow, the flow from when the power is turned on or when returning from sleep has been described, but the dew condensation countermeasure mode is appropriately executed not only at this time but also at the time of image formation or standby. That is, if the power of the image forming apparatus 100 is turned on, Ho and Hi are monitored, and if Ho—Hi> α is satisfied, the dew condensation countermeasure mode started from the first control is executed. Further, in the present embodiment, the image forming apparatus 100 is not put into the sleep state during the execution of the dew condensation countermeasure mode.

[Transition of Ho, Hi, Cnt in dew condensation countermeasure mode]
The transition of the absolute humidity Ho outside the machine, the saturated absolute humidity Hi inside the machine, and the dew condensation counter Cnt in the dew condensation countermeasure mode of the present embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is a graph showing changes over time between the absolute humidity Ho outside the machine and the saturated absolute humidity Hi inside the machine. Further, FIG. 10 is a graph showing changes in the dew condensation counter Cnt over time. The time axis of the horizontal axis of FIGS. 9 and 10 is the same. Further, the external temperature and humidity are adjusted so that Ho changes as shown in FIG.

As shown in FIG. 9, when Ho is lower than Hi, the normal operation is performed. Then, when the temperature and humidity outside the apparatus main body 100a are adjusted to increase Ho, Ho-Hi becomes larger than the first threshold value α (0 in the present embodiment), and the first control is started. At this time, as Ho-Hi becomes larger than 0, the dew condensation counter Cnt for adding Ho-Hi gradually increases as shown in FIG.

When the first control is started, as described above, the cartridge fan 42a and the discharge path fan 42b are stopped, and it becomes difficult for the outside air to enter the inside of the apparatus main body 100a. On the other hand, the temperature inside the device main body 100a gradually rises as the outside air temperature is gradually transmitted or the fixing device 14 and various internal devices generate heat. Then, Hi also gradually rises and becomes higher than Ho. When Ho rises to a predetermined absolute humidity, the external temperature and humidity are adjusted so as to stabilize at that absolute humidity. Then, when Ho-Hi becomes β (-1 in this embodiment) or less, the second control is started. At this time, since Ho-Hi continues to take a negative value, the dew condensation counter Cnt gradually decreases as shown in FIG.

When the second control is started, the outside air enters the inside of the apparatus main body 100a, and an air flow is generated inside. At the start of the second control, since Ho-Hi is β or less, dew condensation is unlikely to occur even if outside air enters. Further, even at the time of the second control, the temperature of the outside is often higher than that of the inside, so that the temperature of the inside rises due to the introduction of the outside air, and the temperature of the inside approaches the temperature of the outside. In addition, the internal temperature tends to rise faster due to the heat generated by the fixing device 14 and various internal devices. As a result, Hi continues to rise, that is, the saturated absolute humidity inside the apparatus main body 100a continues to rise, and dew condensation is less likely to occur inside. Further, Ho-Hi increases in the negative direction, and the dew condensation counter Cnt approaches 0.

Then, when the dew condensation counter Cnt becomes 0 or less for 10 minutes, it is determined that the dew condensation could be dried even if the dew condensation occurs inside the apparatus main body 100a, and the second control is terminated. I am trying to return to normal operation.

[Effect of this embodiment]
In the case of the present embodiment as described above, it is possible to more appropriately take measures against dew condensation in the apparatus main body 100a. That is, as shown in FIG. 9, when Ho—Hi> α, the first control for stopping the cartridge fan 42a and the discharge path fan 42b is executed. When the fan is driven to introduce the outside air into the apparatus main body 100a when Ho-Hi> α is satisfied, the humidity of the outside air is high, so that dew condensation is likely to occur inside. Therefore, in the present embodiment, when Ho—Hi> α is satisfied, the cartridge fan 42a and the discharge path fan 42b are stopped to prevent outside air from entering the inside of the apparatus main body 100a as much as possible.

On the other hand, when Ho—Hi ≦ β is satisfied, the second control for driving the cartridge fan 42a and the discharge path fan 42b is executed. If the fan is left stopped when Ho-Hi ≤ β is satisfied, if dew condensation occurs inside the apparatus main body 100a, there is almost no airflow inside, or even if it occurs, it is very small. This condensation is hard to dry. Therefore, in the present embodiment, when Ho—Hi ≦ β is satisfied, the cartridge fan 42a and the discharge path fan 42b are driven to allow the outside air to enter the inside of the apparatus main body 100a as much as possible, and dew condensation is tentatively generated. Even so, I try to dry this condensation early.

In particular, the cartridge fan 42a and the discharge path fan 42b form an air flow that passes through the surfaces of the dustproof glasses 32a to 32d, which are the emission surfaces of the laser light (exposure light) of the scanner unit 3. Therefore, by driving the cartridge fan 42a and the discharge path fan 42b, it is easier to dry the dew condensation formed on the dustproof glasses 32a to 32d. When dew condensation occurs on the dust-proof glasses 32a to 32d, the laser beam emitted through these glasses is affected and image defects occur. Further, in most cases, when dew condensation occurs, the dustproof glasses 32a to 32d have no means for eliminating the dew condensation other than drying by an air flow. Therefore, in the present embodiment, in the second control, by driving the cartridge fan 42a and the discharge path fan 42b, an air flow passing through the surfaces of the dustproof glasses 32a to 32d is formed, and the dew condensation generated here is early. I am trying to eliminate it.

Further, in the present embodiment, when the state in which the dew condensation counter Cnt is 0 or less continues for the second time (10 minutes in the present embodiment), the second control is terminated. Since the dew condensation counter Cnt is obtained by adding Ho-Hi every first time (10 seconds in this embodiment), the transition of the absolute humidity relationship between the outside and the inside of the apparatus main body 100a is reflected. Is. Therefore, in the present embodiment, when the dew condensation counter Cnt becomes 0, it is determined that the inside of the apparatus main body 100a has begun to dry, and when this state continues for the second time, the dew condensation is dry. I have decided.

Here, in the case of the configuration described in Patent Document 1 described above, since the fan stop time (first predetermined time) is set in advance, the fan stop time may be insufficient depending on the external environment. .. In this case, there is a possibility that moist outside air is introduced into the device main body 100a by driving the fan, and dew condensation is likely to occur inside. On the other hand, in the present embodiment, Ho-Hi that reflects the relationship between the absolute humidity inside and outside the apparatus main body 100a is used, and a second control for driving the fan when Ho-Hi ≦ β is satisfied is used. I am trying to execute. Therefore, control corresponding to the external environment becomes possible, and dew condensation can be less likely to occur even if the outside air is introduced inside, as compared with the configuration described in Patent Document 1.

Further, in the case of the configuration described in Patent Document 1, since the fan drive time (second predetermined time) is also set in advance, the fan drive time may be insufficient depending on the transition of changes in the external and internal environments. , It is possible to stop the fan before the condensation inside dries. On the other hand, in the present embodiment, the dew condensation counter Cnt that reflects the transition of the absolute humidity relationship between the outside and the inside of the apparatus main body 100a is used. Then, when the state in which the dew condensation counter Cnt is 0 or less continues for the second time, the second control is terminated. Therefore, it is possible to control according to the transition of changes in the external and internal environments, and it is easier to dry the dew condensation generated inside than the configuration described in Patent Document 1.

[Other Embodiments]
In the above-described embodiment, the ventilation means are the cartridge fan 42a and the discharge path fan 42b. However, the ventilation means may be one of the cartridge fan 42a and the discharge path fan 42b. For example, if the cartridge fan 42a can sufficiently generate an air flow flowing on the surfaces of the dustproof glasses 32a to 32d, the ventilation means may be only the cartridge fan 42a.

Further, the blowing means may be any one capable of either intake of the device main body 100a or exhaust from the device main body 100a. However, it is preferable to use a fan that generates an air flow on the surfaces of the dustproof glasses 32a to 32d. The first control and the second control may be applied to all the fans included in the image forming apparatus. However, the fan that is driven to protect the device, such as the fixing end fan 42c and the power supply fan 42d of the above-described embodiment, shall be controlled separately from the first control and the second control. Is preferable.

In the above-described embodiment, the case where the heating means is the fixing device 14 has been described. However, the heating means may have another configuration. For example, in order to suppress dew condensation on the photosensitive drum, there is a configuration provided with a drum heater that heats the photosensitive drum. In the case of such a configuration, the drum heater may be used as the heating means, or both the drum heater and the fixing device may be used as the heating means.

Further, in order to suppress dew condensation on the scanner unit, there is a configuration provided with a scanner heater that heats the scanner unit. In the case of such a configuration, the scanner heater may be used as the heating means, or both the scanner heater and the fixing device may be used as the heating means.

Further, there is a configuration provided with a cassette heater in order to heat a sheet (recording material) such as paper in the feeding cassette to reduce the moisture contained in the sheet. In the case of such a configuration, the cassette heater may be used as the heating means, or both the cassette heater and the fixing device may be used as the heating means.

Of the drum heater, scanner heat, and cassette heater, in the case of a configuration including a plurality of heaters, the plurality of heaters may be used as the heating means, or the plurality of heaters and the fixing device may be used as the heating means.

1a, 1b, 1c, 1d ... Photosensitive drum (photoreceptor) / 3 ... Scanner unit (exposure device) / 7a, 7b, 7c, 7d ... Cartridge (process unit) / 14 ... Fixing device (Heating means) / 14a ... Fixing belt (fixing rotating body) / 14b ... Pressurized roller (nip forming member) / 14c ... Heater (heating part) / 19 ... Discharge roller pair (Discharging means) ) / 19a ... Discharge path (transport path) / 32a, 32b, 32c, 32d ... Dustproof glass / 40 ... Environmental sensor (external temperature / humidity detection means) / 41 ... Scanner temperature sensor (inside the machine) Temperature detection means) / 42a ・ ・ ・ Cartridge fan (blower means, 1st blower) / 42b ・ ・ ・ Discharge path fan (blower means, 2nd blower) / 42c ・ ・ ・ Fixing end fan (fixing device blower) Means) / 42d ... Power supply fan (power supply blower means) / 44b ... Fixing end temperature sensor (heating part temperature detection means) / 45 ... Power supply temperature sensor (power supply temperature detection means) / 50 ... Control unit (control means) / 70 ... Power supply unit (power supply) / 71 ... Opening / 100 ... Image forming device / 100a ... Device body / 101 ... Image forming unit

Claims (12)

With the device body
An image forming unit arranged in the main body of the apparatus and forming a toner image on a recording material,
An external temperature / humidity detecting means for detecting the temperature and humidity outside the main body of the device,
An in-flight temperature detecting means for detecting the temperature inside the main body of the device,
An air blowing means having at least one of the functions of intake of outside air into the main body of the device and exhaust of air inside the main body of the device to the outside.
The absolute humidity obtained from the temperature and humidity detected by the outside temperature / humidity detecting means is defined as the outside absolute humidity Ho, and the saturated absolute humidity obtained from the temperature detected by the inside temperature detecting means is defined as the inside saturated absolute humidity Hi. In case,
When the value obtained by subtracting the Hi from the Ho is larger than the first threshold value α, the first control for stopping the blowing means is executed.
When the control executed after the first control and the value obtained by subtracting the Hi from the Ho is equal to or less than the second threshold β which is smaller than the first threshold α, the blowing means is driven. A control means for executing a second control to be made to be provided.
An image forming apparatus characterized in that. When the control means uses the value obtained by subtracting the Hi from the Ho and adding the value for each first time as the count value Cnt.
At the start of execution of the first control, the Cnt is set to 0.
After the execution of the second control is started, when the state in which the Cnt is 0 or less continues for the second time, the second control is terminated.
The image forming apparatus according to claim 1, wherein the image forming apparatus is characterized in that. The image forming unit includes a photoconductor and an exposure device that exposes the surface of the photoconductor to form an electrostatic latent image on the surface of the photoconductor.
The blowing means forms an air flow passing through an emission surface of the exposure light of the exposure apparatus.
The image forming apparatus according to claim 1 or 2, wherein the image forming apparatus is characterized in that. The in-flight temperature detecting means is arranged closer to the exposure apparatus than the outside temperature / humidity detecting means.
The image forming apparatus according to claim 3, wherein the image forming apparatus is characterized in that. The main body of the device is formed with an opening for communicating the inside and the outside.
The external temperature / humidity detecting means is arranged at a position facing the opening in the apparatus main body.
The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is characterized in that. The first threshold value α is set so as to satisfy -1 [g / kg] ≤ α ≤ 1 [g / kg].
The image forming apparatus according to any one of claims 1 to 5, wherein the image forming apparatus is characterized in that. The second threshold β is set so as to satisfy −5 [g / kg] ≦ β <1 [g / kg].
The image forming apparatus according to any one of claims 1 to 6, wherein the image forming apparatus is characterized in that. In at least one of the first control and the second control, the heating means for heating the inside of the apparatus main body is provided.
The image forming apparatus according to any one of claims 1 to 7, wherein the image forming apparatus is characterized in that. The image forming unit has a fixing device that heats a recording material carrying a toner image to fix the toner image on the recording material.
The heating means is the fixing device.
The image forming apparatus according to claim 8, wherein the image forming apparatus is characterized in that. The fixing device includes a rotating fixing rotating body, a heating unit that heats the fixing rotating body, a nip forming member that forms a nip portion that sandwiches and conveys a recording material between the fixing rotating body, and the heating unit. It has a heating part temperature detecting means that can detect the temperature of
At the time of image formation, a fixing device blowing means capable of supplying air to both ends of the fixing rotating body in a width direction intersecting the transport direction of the recording material is provided.
At the time of forming the image, the fixing device blowing means is driven and stopped based on the temperature detected by the heating unit temperature detecting means regardless of whether or not the first control and the second control are executed.
The image forming apparatus according to claim 9, wherein the image forming apparatus is characterized in that. A power source that is arranged in the device body and can supply electric power to each part of the device body,
In order to cool the power supply, a power supply blowing means having at least one function of intake of outside air into the main body of the device and exhaust of air inside the main body of the device to the outside,
A power supply temperature detecting means capable of detecting the temperature of the power supply is provided.
During the first control, the power supply blowing means is driven and stopped based on the temperature detected by the power supply temperature detecting means, and is driven during the execution of the second control.
The image forming apparatus according to any one of claims 1 to 10, wherein the image forming apparatus is characterized in that. The image forming unit fixes the toner image on the recording material by heating a plurality of process units, each of which forms a toner image, and a recording material to which the toner image formed by the plurality of process units is transferred. It has a fixing device, a discharge means for discharging the recording material on which the toner image is fixed by the fixing device, and a transport path for transporting the recording material between the fixing device and the discharge means.
The blower means is arranged in the vicinity of a first blower that sucks outside air toward the plurality of process units and a process unit that is farthest from the first blower among the plurality of process units, and conveys the blower. It has a second blower that draws in outside air toward the road.
The image forming apparatus according to any one of claims 1 to 11, wherein the image forming apparatus is characterized in that.

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