JP2023058051A - Image forming apparatus - Google Patents

Abstract

To solve the problem in which: an image forming apparatus always energizes any one dew condensation prevention means even when the image forming apparatus is powered off, which reduces energy-saving properties.SOLUTION: When the difference in temperature between the inside and outside of an image forming apparatus detected from a plurality of temperature sensors when the image forming apparatus is powered off is equal to or less than a predetermined value, the image forming apparatus sets both a first set time and a second set time set by timer means to 0 and does not drive a heater and a fan, and thereby can improve power-saving properties of the image forming apparatus.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image forming apparatus such as a printer or copier, and more particularly to an image forming apparatus having means for suppressing dew condensation.

2. Description of the Related Art In recent years, there has been known an image forming apparatus in which a heater is arranged in a paper storage section in order to suppress dew condensation on optical system components and a photosensitive drum of a reader section and to suppress moisture absorption of paper stored in the paper storage section. . In such an image forming apparatus, by activating the heater, the ambient temperature around the heater is raised to increase the amount of saturated water vapor, thereby suppressing the occurrence of dew condensation.

Also known is a dew condensation suppression method in which air containing water vapor in the image forming apparatus is exhausted by a fan to reduce the amount of water vapor in the image forming apparatus, thereby suppressing the occurrence of dew condensation.

In Patent Document 1, for example, based on humidity information obtained by a humidity sensor in the image forming apparatus, it is determined whether or not the humidity in the apparatus is equal to or higher than a threshold value, and a fan or fan is used as means for suppressing condensation after the power is turned off. Control methods are known to select one of the heaters.

JP 2019-012226 A

However, the configuration of Japanese Patent Application Laid-Open No. 2002-200010 simply selects whether the fan or the heater is used as dew condensation suppression means depending on whether the humidity in the image forming apparatus is equal to or higher than a threshold value. Therefore, even if the image forming apparatus is in a power-off state, one of the dew condensation suppressing means is energized, so there is a problem that energy saving performance is reduced.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image forming apparatus capable of improving the energy saving performance of the image forming apparatus even if it is configured to include dew condensation suppression means.

An image forming apparatus that forms an image on a sheet, comprising: a power switch; a control section that controls the image forming apparatus when the power switch is turned on; and power for supplying power to the control section. a supply circuit, a heater provided inside the image forming apparatus, a fan for discharging air from inside the image forming apparatus to the outside, a humidity detection section for detecting humidity inside the image forming apparatus, and the image forming apparatus. a first temperature detection unit that detects the temperature inside the image forming apparatus; and a second temperature detection unit that detects the temperature outside the image forming apparatus, wherein the power supply circuit includes a power supply circuit and the power switch. a switching circuit that connects the power supply circuit to a main circuit including the control unit when the switch is turned on, and connects the power supply circuit to a sub circuit including the heater and the fan when the power switch is turned off; wherein the sub-circuit includes a heater drive contact, a fan drive contact, and when the power switch is turned off, conducts the heater drive contact for a first set time to drive the fan. and a timer means for causing the contact of the image forming apparatus to conduct for a second set time, and the control unit determines whether the humidity inside the image forming apparatus is equal to or higher than a threshold based on the humidity information detected by the humidity detection unit. the first set time is set to 0 and the second set time is set to a time greater than 0, and if the humidity inside the image forming apparatus is less than the threshold value, the first The set time is set to a time greater than 0, the second set time is set to 0, and the temperature difference detected by the first temperature detection unit and the second temperature detection unit is equal to or less than a predetermined value. In case, the first set time and the second set time by the timer means are both set to 0, and the heater and the fan are not driven.

According to the present invention, if the temperature difference between the inside and the outside of the image forming apparatus is small, power is not supplied to the dew condensation suppressing means after the power is turned off.

Schematic cross-sectional view of an image forming apparatus according to the present invention FIG. 2 is a diagram for explaining control blocks of an image forming apparatus according to the present invention; Flowchart of CPU of image forming apparatus according to the present invention

<First embodiment>
This embodiment will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 equipped with the present invention.

First, the cassette 111 is provided so as to be able to be pulled out in the front direction of FIG. 1, and the user sets paper, an OHT, or the like as a sheet S on which an image is to be formed. A document is set on the image reading unit 150 by the user, and after image data is read by input from the operation unit 424, image information is processed by a controller (not shown).

Further, a laser beam is emitted from the laser scanner unit 142 according to a signal based on the processing result, an electrostatic latent image is formed on the photosensitive drum 141, and the electrostatic latent image on the photosensitive drum 141 is developed by the developing device 143. A toner image is formed on the photosensitive drum 141 .

After that, the primary transfer device 144 applies a predetermined pressure and an electrostatic load bias, and the toner image is transferred onto the intermediate transfer belt 145 . In the case of FIG. 1, the image forming section 140 described above is provided with four sets of yellow Y, magenta M, cyan C and black Bk.

Next, the intermediate transfer belt 145 is described. The intermediate transfer belt 145 is transported and driven in the direction of arrow A in FIG. Therefore, parallel processing is performed by the Y, M, C, and Bk image forming units described above. The image forming process of each color is performed at the timing of superimposing it on the upstream toner image that has been primarily transferred onto the intermediate transfer belt 145 . As a result, a full-color toner image is finally formed on the intermediate transfer belt 145 and conveyed to the secondary transfer portion 130 .

On the other hand, sheets S such as papers and OHTs stacked and accommodated in the cassette 111 are separated and fed one by one by the paper feeding unit 110 . The fed sheet S is transferred to the first conveying roller pair 120 and conveyed toward the sheet skew correcting device 10 arranged downstream in the sheet conveying direction, where the skew of the sheet S is corrected. After that, the sheet S is conveyed to the secondary transfer portion 130 by the second conveying roller pair 30 .

A full-color toner image is secondarily transferred onto the sheet S in the secondary transfer portion 130 by the conveying process of the sheet S and the image forming process described above. After that, the sheet S is conveyed to the fixing device 155 .

The fixing device 155 melts and fixes the toner onto the sheet S by applying a predetermined pressing force from substantially opposing rollers or belts and a heating effect generally from a heat source such as a heater.

In the case of single-sided printing, the sheet S on which the toner image has been fixed in this way is directly transferred to the first paper discharge tray 170 or the second paper discharge roller 161 by the first paper discharge roller 160 or the second paper discharge roller 161 by a solenoid (not shown). It is discharged onto the second paper discharge tray 171 . Further, in the case of double-sided printing, a path selection is made as to whether the first sheet discharging roller 160 is reversely rotated and the sheet is conveyed to the reversing conveying device 180 . A first paper discharge tray sensor 172 and a second paper discharge tray sensor 173 for detecting the presence or absence of the discharged sheet S are arranged on the two paper discharge trays, respectively.

A cassette heater 404 for suppressing moisture absorption of the sheets S stored in the cassette 111 is provided below the cassette 111 . The image reading unit 150 is provided with a reader heater 405 for suppressing dew condensation on optical system components inside the image reading unit 150 . The image forming section 140 is provided with a drum heater 406 for suppressing dew condensation on the photosensitive drum 141 . As described above, the image forming apparatus 100 of this embodiment has a plurality of heaters such as the cassette heater 404 , the reader heater 405 and the drum heater 406 .

A drum heater 406 is arranged for each photosensitive drum of each color. A side of the image forming apparatus 100 is provided with an exhaust fan 407 that exhausts air containing water vapor inside the image forming apparatus 100 to the outside. The image forming apparatus 100 is provided with a humidity sensor 408 as a humidity detection unit that measures the internal humidity of the image forming apparatus 100 . Furthermore, a temperature sensor 409 as a first temperature detection unit for measuring the internal temperature of the image forming apparatus 100 and a temperature sensor 410 as a second temperature detection unit for measuring the external temperature of the image forming apparatus 100 are provided.

Next, a control block diagram of the image forming apparatus 100 of this embodiment will be described with reference to FIG.

When the power switch 401 is pressed to turn on the power of the image forming apparatus 100, the AC power supplied from the power plug 400 to the power supply circuit of 403 is supplied to the main circuit of 412, and the image forming apparatus 100 is started. . The power supply circuit 403 includes a power supply circuit 411 mainly composed of a filter circuit and a switching circuit 414 for switching the AC power supply between the main circuit 412 and the sub-circuit 413 .

The main circuit 412 is a circuit to which AC power is supplied while the image forming apparatus 100 is powered on. AC power is supplied to a DC load 423 to which DC power is supplied via a DC power supply 421, which is an AC-DC converter, and to an AC load 422 such as a fixing heater (not shown).

The control part 402 contains CPU426, ROM427, and RAM428. The CPU 426 executes commands based on control programs stored in the ROM 427 . The CPU 426 is also connected to each load such as an image forming section and a sheet feeding/conveying section (not shown), and executes control of each load according to commands from the CPU 426 . Furthermore, the CPU 426 receives information from various sensors such as the humidity sensor 408 that detects the humidity inside the image forming apparatus 100 , the temperature sensor 409 and the temperature sensor 410 via the sensor IF 429 . The CPU 426 communicates with a controller unit 425 that controls the operation unit 424 and controls the printer based on input information to the operation unit 424 .

The sub-circuit 413 is a circuit to which AC power is supplied after the image forming apparatus 100 is powered off. In the sub-circuit 413 , AC power is supplied to the heaters 404 , 405 , 406 and the DC power supply 419 for the exhaust fan 407 through the heater drive contacts 415 , 416 , 417 and the fan drive contact 418 .

The heaters described above include a cassette heater 404 that suppresses moisture absorption of the sheets S stored in the cassette 111, a reader heater 405 that suppresses dew condensation on the optical system components inside the image reading unit 150, and a drum heater that suppresses dew condensation on the photosensitive drum 141. 406 applies.

In the present embodiment, the exhaust fan 407 is driven by a DC power supply AC-DC converted by a dedicated DC power supply 419, but the exhaust fan 407 may be an AC fan driven by an AC power supply. 419 becomes unnecessary. Before the image forming apparatus 100 is turned off by pressing the power switch 401 and the AC power supply destination is switched in the switching circuit 414, the conduction time of the driving contacts 415, 416, 417, and 418 is set. A value is sent from the controller 402 to the timer 420 . The set value of the conduction time of the drive contacts 415 , 416 , 417 and 418 is set based on the detected values of the humidity sensor 408 and the temperature sensors 409 and 410 .

The conduction time of the heater drive contact is called the first set time, and the conduction time of the fan drive contact is called the second set time. The heater drive contacts 415, 416, 417 and the fan drive contact 418 supply AC power to the heaters 404, 405, 406 and the DC power supply 419 for the exhaust fan 407 based on the conduction time setting values described above. The details of the conduction time set values (first set time, second set time) will be described later.

FIG. 3 is a flow chart of the CPU 426, which is the control means of the image forming apparatus 100 in this embodiment. A control flow of the CPU 426 will be described with reference to FIG.

3 starts when the image forming apparatus 100 is powered on. First, the CPU 426 confirms whether or not the power switch 401 has been pressed to turn off the power.

In S102, it is determined whether the difference between the temperature inside the image forming apparatus 100 detected by the temperature sensor 409 and the temperature outside the image forming apparatus 100 detected by the temperature sensor 410 is equal to or less than a predetermined value. If the temperature difference between the inside and outside of the image forming apparatus 100 is equal to or less than the predetermined value (Yes in S102), it is determined that dew condensation does not occur, and the process ends.

If the temperature difference between the inside and outside of the image forming apparatus 100 calculated from the detection results of the temperature sensors 409 and 410 is not equal to or less than the predetermined value (No in S102), the process proceeds to S103.

The above-mentioned predetermined value used as the criterion for determining the temperature difference may be set from the operation unit 424. Since the temperature difference condition causing condensation varies depending on the humidity, the value detected by the humidity sensor 408 is automatically used. It may be set, and shall be set approximately between 5°C and 10°C. In S103, it is determined whether the humidity inside the image forming apparatus 100 detected by the humidity sensor 408 is equal to or higher than a threshold. The threshold value of the humidity detected by the humidity sensor 408 may be set from the operation unit 424 . Further, since the maximum amount of water vapor in the air changes depending on the temperature, it may be automatically set from the value detected by the temperature sensor 409 in the image forming apparatus 100, and should be set at around 80%.

When the humidity inside the image forming apparatus 100 is equal to or higher than the threshold, the first set time of the timer 420 is set to 0 and the second set time is set to Tf (>0) (S104). In other words, since the amount of water vapor in the image forming apparatus 100 is too large, the dew condensation suppression heaters (404, 405, 406) cannot suppress the occurrence of condensation. method to suppress the occurrence of dew condensation. Subsequently, in S105, the connection destination of the power supply circuit 411 is switched from the main circuit 412 to the sub circuit 413, and the process ends.

When the humidity inside the image forming apparatus 100 is less than the threshold, the first set time of the timer 420 is set to Th (>0) and the second set time is set to 0 (S106). In other words, since the amount of water vapor in the image forming apparatus 100 is small and there is no need to operate the exhaust fan 407, the dew condensation suppression heaters (404, 405, 406) with low power consumption are operated by Th to suppress the occurrence of dew condensation. take a way to Subsequently, the process proceeds to S105, the connection destination of the power supply circuit 411 is switched from the main circuit 412 to the sub circuit 413, and the process ends.

Here, regarding the first set time Th, which is the operation time of the dew condensation suppression heaters 404, 405, and 406, the power switch 401 is pressed to turn off the power until the next time the power switch 401 is pressed to turn on the power. It's good to be time. Therefore, the average value calculated from the power-off time and the power-on time by the control unit 402 may be used, or if the power-off time and the power-on time are set to a predetermined time, the time between them may be used.

Also, the second set time Tf, which is the operation time of the discharge fan 407, may be set from the operation unit 424. FIG. Since the conditions for reducing the amount of water vapor to suppress the occurrence of dew condensation vary depending on the humidity, it may be automatically set based on the detected value of the humidity sensor 410, and is generally set within 30 minutes to 1 hour. and

In this flowchart, the operation time Th of the dew condensation suppression heaters 404, 405, and 406 has been described as a common set time Th instead of an individual time for each heater, but it may be changed according to the characteristics and location of each heater. . For example, as shown in FIG. 2, they may be individually settable in terms of electric circuits.

By performing control based on the above control flow, if the temperature difference between the inside and the outside of the image forming apparatus is small, it is not necessary to supply power to the dew condensation suppression means after the power is turned off, further improving the energy saving performance of the image forming apparatus. can be made

REFERENCE SIGNS LIST 100 image forming apparatus 404 cassette heater 405 reader heater 406 drum heater 407 exhaust fan 408 humidity sensor 409 temperature sensor (inside machine)
410 temperature sensor (external)

Claims (7)

An image forming apparatus for forming an image on a sheet,
a power switch;
a control unit that controls the image forming apparatus with the power switch turned on;
a power supply circuit for supplying power to the control unit;
a heater provided inside the image forming apparatus;
a fan for discharging air from the inside of the image forming apparatus to the outside;
a humidity detection unit that detects the humidity inside the image forming apparatus;
a first temperature detection unit that detects the temperature inside the image forming apparatus;
a second temperature detection unit that detects the temperature outside the image forming apparatus,
The power supply circuit connects the power supply circuit to the main circuit including the control section when the power switch is turned on, and connects the power supply circuit to the heater when the power switch is turned off. and a switching circuit connected to a sub-circuit containing the fan,
The sub-circuit connects a heater drive contact, a fan drive contact, and the heater drive contact for a first set time when the power switch is turned off. timer means for conducting for a second set time;
Based on the humidity information detected by the humidity detection unit, the control unit sets the first set time to 0 and sets the second set time when the humidity inside the image forming apparatus is equal to or higher than a threshold value. setting the time to a time greater than 0, and setting the first set time to a time greater than 0 when the humidity inside the image forming apparatus is less than the threshold value, and setting the second set time to a time greater than 0; set to 0,
When the temperature difference detected by the first temperature detection section and the second temperature detection section is equal to or less than a predetermined value, both the first set time and the second set time by the timer means are set to 0. , the image forming apparatus, wherein the heater and the fan are not driven. The heater is a plurality of heaters arranged at different locations inside the image forming apparatus, and the first set time for conducting the contact for driving the heater can be individually set for each of the plurality of heaters. 2. The image forming apparatus according to claim 1, wherein: further comprising a cassette for accommodating sheets,
The heater has a cassette heater that suppresses moisture absorption of the sheets accommodated in the cassette.
3. The image forming apparatus according to claim 2, wherein: further comprising an image reading unit that has an optical system component and reads image data of the document,
The heater has a reader heater that is provided in the image reading unit and suppresses dew condensation on the optical system parts.
4. The image forming apparatus according to claim 2, wherein: further comprising a photosensitive drum on which a toner image is formed,
The heater has a drum heater for suppressing dew condensation on the photosensitive drum,
5. The image forming apparatus according to claim 2, wherein: 6. The image forming apparatus according to claim 1, wherein said predetermined value is automatically set from a value detected by said humidity detection section. The image forming apparatus according to any one of claims 1 to 6, wherein the threshold value is automatically set from a value detected by the first temperature detection section.

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