JP2016014821A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can determine the number of UFPs without using a measuring instrument such as a particle counter.SOLUTION: An image forming apparatus includes a fixing device 110 that may involve the generation of ultra fine particles during drive, a UFP reduction part 120 that reduces the amount of discharge of the ultra fine particles to the outside of the apparatus, and a control part 140 that controls reduction means on the basis of an estimated value of the amount of generation of the ultra fine particles. The control part 140 increases or decreases the estimated value of the amount of generation of the ultra fine particles that are likely to be generated at a predetermined fixing temperature and in standard conditions, on the basis of at least one of the size of sheets, whether single-sided printing or double-sided printing, image printing rate, lapse of time from the completion of heating for use of the fixing device, count of use of the fixing device, and outside temperature.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a FAX, and a printer multifunction machine. In particular, the amount of ultra fine particles (UFP for short) generated from a fixing device mounted on the image forming apparatus is reduced. It relates to reducing technology.

  In the image forming apparatus, an image is formed on a sheet by thermally fixing an unfixed toner image transferred onto the sheet. The fixing device heat-fixes the sheet by passing the sheet through a fixing nip formed by pressing a pair of fixing members and pressing the sheet while heating. The fixing member is a cylindrical roller or an endless belt, and generally has an elastic layer made of silicon rubber.

  However, when the silicon rubber of the fixing member becomes high temperature, the low-molecular siloxane in the silicon rubber volatilizes and aggregates in the process of being exhausted to form ultrafine particles having a particle size of 100 nm or less (Ultra Fine Particles, “UFP” for short). Is considered to be generated. Further, it is considered that when the toner is heated and dissolved in the fixing device, a part of the toner component is volatilized and condensed to generate UFP.

The amount of UFP released by the fixing device is extremely small and does not immediately have an adverse effect on the human body or the environment. However, given that people's awareness of environmental protection has recently increased, It is desirable not to release as much as possible even if it is a trace amount.
As a conventional technique for reducing UFP emitted from an image forming apparatus, for example, a technique for capturing UFP with a fine filter is disclosed (for example, see Patent Document 1). In addition, for example, a technique is disclosed in which the inside of the exhaust duct is not heated to aggregate the components that are the source of UFP (see, for example, Patent Document 2).

JP 2012-128013 A JP 2013-3507 A

  In the technique of Patent Document 1, in order to extend the life of the filter, the number of UFPs is detected using a particle counter, and when a large number of UFPs are detected, a fine filter for collecting UFPs is used. When it is detected that there is little, a coarse filter for dust is used. The particle counter is an independent measuring instrument that measures the number of fine particles of a specific size by measuring the intensity of light scattering from fine particles and taking out the light intensity proportional to the particle size as an electrical signal. is there. As described above, the particle counter is relatively expensive because it has a relatively complicated structure, and has a problem that it greatly affects the price of the image forming apparatus. Further, since a space for installing the particle counter is required, there is a problem that the image forming apparatus is increased in size.

  In the technique of Patent Document 2, the inside of the exhaust duct is always heated by a heater so that the temperature becomes higher than the temperature at which UFP does not condense. However, the amount of UFP generated is not always constant and varies depending on the printing conditions and the usage environment. Therefore, there is a problem that even when almost no UFP is generated, the heater is heated and wasteful energy is consumed.

  The present invention has been made in view of the above-described problems, and provides a first image forming apparatus capable of knowing the number of UFPs without using a measuring instrument such as a particle counter. Objective. It is a second object of the present invention to provide an image forming apparatus capable of suppressing wasteful energy consumption in a mechanism for reducing UFP.

  In order to achieve the above object, an image forming apparatus of the present invention includes a fixing device that may be accompanied by generation of ultrafine particles during driving, a reducing unit that reduces the amount of ultrafine particles released to the outside of the machine, Control means for controlling the reduction means based on the estimated value of the generation amount, the control means of the generation amount of ultrafine particles that would be generated under standard conditions at a preset fixing temperature. The estimated value is at least one of paper size, single-sided printing or double-sided printing, image printing rate, elapsed time since the end of previous heating use of the fixing device, usage count of the fixing device, and outside air temperature. Increase or decrease based on.

Here, the control means can control the reducing means to reduce the ultrafine particles when the estimated value of the generated amount exceeds a predetermined value.
Here, the control means can increase the estimated value of the generation amount in the case of single-sided printing than in the case of double-sided printing.
Here, when the image printing rate is higher than the standard condition, the control unit increases the estimated value of the generation amount or when the image printing rate is lower than the standard condition. The estimated value of the generated amount can be reduced.

Here, the control means increases the estimated value of the generated amount when the elapsed time from the end of the previous heating use of the fixing device is longer than the standard condition, or When the elapsed time from the end of the previous heating use of the fixing device is shorter than the condition, the estimated value of the generated amount can be reduced.
Here, the control unit increases the estimated value of the generated amount when the usage count of the fixing device is larger than the standard condition, or the control unit is configured to increase the estimated value of the fixing device than the standard condition. When the usage count is small, the estimated value of the generation amount can be reduced.

Here, when the outside air temperature is lower than the standard condition, the control means increases the estimated value of the generation amount, or when the outside temperature is higher than the standard condition, The estimated amount of generation can be reduced.
Here, the image forming apparatus further includes an exhaust unit that takes in the gas generated in the fixing device into the duct, and discharges the taken-in gas out of the machine from the duct. By heating, the amount of ultrafine particles released to the outside of the machine can be reduced.

Here, the reduction means can vary the output in multiple steps or steplessly, and the control means can change the output of the reduction means based on the estimated value of the amount of ultrafine particles generated. .
Here, the image forming apparatus further includes an exhaust unit that takes in the gas generated in the fixing device into the duct, and discharges the taken-in gas out of the duct from the duct. By passing the gas through the collection filter, it is possible to reduce the amount of ultrafine particles released to the outside.

  Here, the image forming apparatus further includes an exhaust unit that takes in the gas generated in the fixing device into the duct, and discharges the taken-in gas out of the duct from the duct. By charging the ultrafine particles and passing the gas in the duct through an electrostatic filter, it is possible to reduce the amount of ultrafine particles released to the outside.

  By providing the above configuration, the number of UFPs can be estimated according to the fixing temperature and other parameters, so that the number of UFPs can be known without using a measuring instrument such as a particle counter. Further, when almost no UFP is generated, it is possible to control the UFP not to be reduced, or to operate in the energy saving mode and limit the ability to reduce the ultrafine particles. Energy consumption can be reduced.

1 is a diagram illustrating a configuration of a printer according to an embodiment. It is a figure which shows the structure of the fixing roller and pressure roller in a fixing device. 1 is a diagram illustrating an outline of an image forming apparatus according to an embodiment. It is a figure which shows the specific example of a UFP reduction part and an exhaust part. It is a figure which shows the other specific example of a UFP reduction part and an exhaust part. It is a figure which shows correlation with fixing temperature and an image printing rate, and the amount of UFP generation | occurrence | production. It is a figure which shows correlation with outside temperature and UFP generation amount. FIG. 7 is a diagram illustrating a correlation between an elapsed time from the end of the previous heating use of the fixing device and a UFP generation amount. FIG. 6 is a diagram illustrating a correlation between a usage count of a fixing device and a UFP generation amount. It is a figure which shows an example of the method of estimating the generation amount of UFP. It is a figure which shows an example of a 1st table. It is a figure which shows an example of a 2nd table. It is a figure which shows an example of a 3rd table. It is a figure which shows an example of a 4th table.

<Embodiment>
<Configuration>
Hereinafter, a case where an embodiment of an image forming apparatus according to the present invention is applied to a tandem color digital printer (hereinafter simply referred to as “printer”) will be described as an example.
[1] Configuration of Printer First, the configuration of the printer 1 according to the present embodiment will be described. FIG. 1 is a diagram illustrating a configuration of a printer 1 according to the present embodiment. As shown in FIG. 1, the printer 1 includes an image process unit 3, a paper feed unit 4, a fixing device 5, and a control unit 60.

  When the printer 1 is connected to a network (for example, a LAN) and receives a print instruction from one or more external terminal devices (not shown) or an operation panel (not shown), yellow, magenta, cyan, and black are received based on the instructions. The toner images of the respective colors are formed, and these are multiple-transferred to form a full-color image, thereby executing a printing process on the recording sheet. Hereinafter, the reproduction colors of yellow, magenta, cyan, and black are expressed as Y, M, C, and K, and Y, M, C, and K are added as subscripts to the numbers of the components related to the reproduction colors.

The image processing unit 3 includes image forming units 3Y, 3M, 3C, and 3K, an exposure unit 10, an intermediate transfer belt 11, a secondary transfer roller 46, and the like. Since the image forming units 3Y, 3M, 3C, and 3K have the same configuration, the configuration of the image forming unit 3Y will be mainly described below.
The image forming unit 3Y includes a photosensitive drum 31Y, a developing device 32Y, a charger 33Y, a primary transfer roller 34Y, and the like disposed around the photosensitive drum 31Y. A Y-color toner image is formed on the photosensitive drum 31Y. Create an image. The developing device 32Y faces the photosensitive drum 31Y and conveys charged toner to the photosensitive drum 31Y.

The intermediate transfer belt 11 is an endless belt, is stretched around a driven roller 12 and a driving roller 13, and is driven to rotate in the direction of arrow C. Further, a cleaner 14 for removing toner remaining on the intermediate transfer belt is disposed in the vicinity of the driven roller 12.
The exposure unit 10 includes a light emitting element such as a laser diode, emits laser light L for forming images of Y to K colors in response to a drive signal from the control unit 60, and each of the image forming units 3Y, 3M, 3C, and 3K. The photosensitive drum is exposed and scanned. By this exposure scanning, an electrostatic latent image is formed on the photosensitive drum 31Y charged by the charger 33Y. Similarly, electrostatic latent images are formed on the photosensitive drums of the image forming units 3M, 3C, and 3K.

  The electrostatic latent image formed on each photoconductor drum is developed by each developing unit of the image forming units 3Y, 3M, 3C, and 3K, and a toner image of a corresponding color is formed on each photoconductor drum. The formed toner image has primary transfer rollers for the image forming units 3Y, 3M, 3C, and 3K (in FIG. 1, only the primary transfer roller corresponding to the image forming unit 3Y is denoted by reference numeral 34Y, and other primary transfer rollers). ), The primary transfer is sequentially performed on the intermediate transfer belt 11 at different timings so as to be superimposed at the same position on the intermediate transfer belt 11, and then the secondary transfer roller. The toner images on the intermediate transfer belt 11 are collectively transferred onto the recording sheet by the action of the electrostatic force 46.

The photoreceptors of the image forming units 3Y, 3M, and 3C used in color printing are configured so as to be able to contact and separate from the intermediate transfer belt 11. When performing monochrome printing, the photosensitive members are formed. The photoreceptors of the image portions 3Y, 3M, and 3C and the intermediate transfer belt 11 are separated from each other. When performing color printing, the photoreceptors and the intermediate transfer belt 11 are in contact with each other.
As a mechanism for contacting / separating between the intermediate transfer belt and each photoconductor during color printing and monochrome printing, for example, electromagnetic mechanisms as disclosed in a patent document (Japanese Patent Laid-Open No. 10-181927) are disclosed. A belt device mechanism using a clutch, a clutch gear, an arm, or the like can be used (see the description in paragraphs 43, 44, and 52 to 55 and the description in FIGS. 2 and 3).

The recording sheet on which the toner image has been secondarily transferred is further conveyed to the fixing device 5, and the toner image (unfixed image) on the recording sheet is heated and pressed by the fixing device 5 and thermally fixed to the recording sheet. .
During single-sided printing, the thermally fixed recording sheet is conveyed to the discharge roller 71 via the switching guide member 70 and is discharged to the discharge tray 80 by the discharge roller 71. During double-sided printing, one side is thermally fixed. The recording sheet is conveyed to the reverse roller 72 via the switching guide member 70.

When the recording sheet having one surface thermally fixed is conveyed, the reversing roller 72 reverses the conveying direction of the recording sheet and is conveyed to the conveying roller 73 via the switching guide member 70. The recording sheet transported to the transport roller 73 is further transported sequentially to the transport rollers 74, 75, and 76, guided to the timing roller 45, and the recording sheet surface is reversed.
Thereafter, the recording sheet on which one side is thermally fixed is conveyed again to the secondary transfer position 47 via the timing roller 45, and the toner image is secondary-transferred to the side of the recording sheet on which the toner image is not thermally fixed. After that, it is thermally fixed by the fixing device 5, conveyed to the discharge roller 71 through the switching guide member 70, and discharged to the discharge tray 80 by the discharge roller 71. As a result, the toner images are thermally fixed on both sides of the recording sheet, and double-sided printing is completed for the recording sheet.

  The switching guide member 70 is disposed at a branch point between a conveyance path from the fixing device 5 toward the discharge roller 71 and a conveyance path from the fixing device 5 toward the reversing roller 72, and rotates to thereby change the conveyance path of the recording sheet. , Switching to either the discharge roller 71 side or the reverse roller 72 side. The switching guide member 70 is rotated by, for example, a drive motor. The control unit 60 controls the drive of the drive motor, whereby the rotation of the switching guide member 70 is controlled.

Further, an exhaust duct 310 and an exhaust fan 311 for exhausting hot air staying around the image forming unit are provided inside the apparatus. As a result, the staying hot air is exhausted so that the toner in the developing device does not melt due to the staying hot air. Further, an in-machine temperature sensor 320 for measuring the in-machine temperature is provided in the vicinity of the image forming unit 3K.
The paper feeding unit 4 feeds the fed recording sheet to the timing roller 45, the paper feeding cassette 41 that accommodates the recording sheet, the feeding roller 42 that feeds the recording sheets in the paper feeding cassette 41 one by one on the feeding path. Conveying rollers 43 and 44, and a timing roller 45 that conveys the recording sheet at a timing of feeding to the secondary transfer position 47 are provided.

The number of paper feed cassettes is not limited to one and may be plural. As the recording sheet, paper sheets (plain paper, thick paper) having different sizes and thicknesses, and film sheets such as an OHP sheet can be used. When there are a plurality of paper feed cassettes, recording sheets having different sizes, thicknesses or materials may be stored in the paper feed cassettes.
The timing roller 45 conveys the recording sheet to the secondary transfer position 47 in accordance with the timing at which the toner image primarily transferred onto the intermediate transfer belt 11 is conveyed to the secondary transfer position so as to be superimposed at the same position. It is brought into contact with the intermediate transfer belt 11. Then, the toner images on the intermediate transfer belt 11 are collectively transferred onto the recording sheet by the secondary transfer roller 46.

Each of the rollers such as the feeding roller 42, the transport rollers 43 and 44, and the timing roller 45 is rotationally driven through a power transmission mechanism (not shown) such as a gear and a belt using a transport motor (not shown) as a power source. . As the transport motor, for example, a stepping motor capable of controlling the rotational speed with high accuracy is used.
The fixing device 5 includes a fixing roller 51 and a pressure roller 52. A recording sheet on which a toner image is secondarily transferred is inserted into a fixing nip formed between both rollers, and the recording sheet is pressed. The toner image is heat-fixed on the recording sheet by heating. The fixing roller 51 includes a heating element such as a halogen heater, and the temperature of the fixing device 5 is controlled by controlling the on / off of the heating element by the control unit 60. The heating method of the fixing device is not limited to the heat roller method as described above, and may be, for example, an electromagnetic induction heating method or a heating method using a resistance heating element.

Further, the fixing roller 51 is rotated by a driving force such as a driving motor, and the pressure roller 52 is driven to rotate as the fixing roller 51 rotates. This rotation control is performed by the control unit 60.
[2] Detailed Configuration of Fixing Device FIG. 2 is a diagram illustrating the structure of the fixing roller 51 and the pressure roller 52 in the fixing device 5.

  The fixing roller 51 has, for example, a diameter of 40 mm, a cylindrical aluminum cored bar 51 a (3 mm thickness) containing a heating element such as a halogen heater, an elastic layer 51 b (2 mm thickness) made of silicon rubber, PFA ( A surface layer 51c (50 μm thick) made of a fluororesin) tube is included. The pressure roller 52 has, for example, a diameter of 40 mm, and includes an aluminum cored bar 52a (diameter 32 mm), a silicon rubber elastic layer 52b (4 mm thickness), and a PFA tube surface layer 52c (50 μm thickness).

[3] Functional Configuration FIG. 3 is a diagram showing an outline of the image forming apparatus 100 according to the present embodiment.
The image forming apparatus 100 corresponds to the printer 1 and includes a fixing device 110, a UFP reduction unit 120, an exhaust unit 130, and a control unit 140.
The fixing device 110 corresponds to the fixing device 5 and includes a generation source of ultrafine particles such as a silicone rubber elastic layer, and may be accompanied by generation of ultrafine particles during driving.

The UFP reduction unit 120 reduces the amount of UFP released to the outside.
The exhaust unit 130 takes in a gas containing low-molecular siloxane, which is a source of UFP generated from the fixing device 110 during driving, into the duct, and exhausts the taken-in gas out of the machine from the duct.
FIG. 4 is a diagram illustrating specific examples of the UFP reduction unit 120 and the exhaust unit 130. As shown in FIG. 4, suction ports of the duct 131 are provided toward the paper inlet and outlet openings of the fixing device 110, and the gas generated from the fixing device 110 is taken into the duct 131. A fan 132 is provided at the outlet of the duct 131 so that the gas in the duct 131 can be quickly discharged out of the machine. In the duct 131, for example, a resistance heater heating heater 121 is provided as the UFP reduction unit 120. By heating the gas taken in the duct 131, the ultrafine particles are reduced in the duct 131, and the ultrafine particles are reduced. Can be reduced. In addition, it is preferable that the heater 121 varies the output in multiple steps or steplessly, for example, by varying the input voltage.

  FIG. 5 is a diagram illustrating another specific example of the UFP reduction unit 120 and the exhaust unit 130. As shown in FIG. 5, suction ports of the duct 131 are provided toward the openings of the paper inlet and outlet of the fixing device 110, and the gas generated from the fixing device 110 is taken into the duct 131. A fan 132 is provided at the outlet of the duct 131 so that the gas in the duct 131 can be quickly discharged out of the machine. The duct 131 has two paths, and the UFP collection filter 122 is provided only on one path as the UFP reduction unit 120. By passing the gas in the duct 131 through the collection filter 122, ultrafine particles are provided. Can be reduced. A movable valve 123 is provided at the branch point of the two paths, and it is possible to select whether or not to pass the gas in the duct 131 through the collection filter 122.

It is also effective to reduce the amount of ultrafine particles released to the outside by providing a UFP ionization device for charging UFP in the duct 131 and providing an electrostatic filter instead of the collection filter 122.
The control unit 140 controls the UFP reduction unit 120 based on the estimated value of the UFP generation amount. More specifically, the control unit 140 calculates an estimated value of the amount of ultrafine particles that will be generated under standard conditions at a preset fixing temperature, whether it is paper size, double-sided printing or single-sided printing, and image printing rate. It increases or decreases based on at least one of the elapsed time from the previous heating use of the fixing device 110, the usage count of the fixing device 110, and the outside air temperature.

Here, the standard conditions are, for example, as follows.
-Elapsed time since the last heating use of the fixing device: Saturation time (12 hours) or more-Usage count of the fixing device: Saturation count (10 kp) or more-Printing paper: CF80 (recommended paper basis weight 80 g / m ² ) A4 Size / printed image: 0% image printing rate (blank paper)
・ Outside air temperature: 23 ℃
In addition, it is preferable that the control unit 140 controls the UFP reduction unit 120 to reduce the ultrafine particles when the estimated value of the UFP generation amount exceeds a predetermined value. In addition, when the estimated value of the amount of UFP generated does not exceed the predetermined value, the control unit 140 stops the operation of the reduction unit so as not to reduce the ultrafine particles, or operates the reduction unit in the energy saving mode. It is preferable to limit the ability to reduce ultrafine particles. Here, the predetermined value is, for example, about “1 × 10 ⁸ pieces / 10 minutes” to “1 × 10 ¹¹ pieces / 10 minutes”.

In addition, when using the heater 121 as the UFP reduction unit 120, the controller 140 not only turns the heater 121 on / off but also changes the output of the heater 121 based on the estimated value of the amount of UFP generated. Thus, it is preferable to reduce the amount of ultrafine particles released to the outside with the minimum necessary power.
A method for estimating the amount of UFP generated will be described in detail below.

  FIG. 6 is a diagram showing a correlation between the fixing temperature and the image printing rate and the UFP generation amount. FIG. 6 shows the case of single-sided printing with an image printing rate of 20% (A in FIG. 6), the case of single-sided printing with an image printing rate of 0% (blank) (B in FIG. 6), and the image with double-sided printing. A case where the printing rate is 20% (C in FIG. 6) and a case where the image printing rate is 0% (blank) in double-sided printing (D in FIG. 6) are shown. The fixing temperature on the horizontal axis is an actual measurement value obtained by measuring the center of the surface of the fixing belt 53 using a non-contact infrared temperature sensor. The UFP number ratio on the vertical axis is a ratio when the number of UFP generation is 1 when single-sided printing, image printing rate is 20%, and the fixing temperature is 180 ° C.

  As shown in FIG. 6, it can be seen that in any case, the amount of UFP generated increases as the fixing temperature increases. This is presumably because the volatilization amount of the low-molecular siloxane increases as the temperature of the silicon rubber elastic layer of the fixing belt 53 and the pressure roller 52 increases. It can also be seen that the UFP generation amount with an image printing rate of 20% is higher than the UFP generation amount with an image printing rate of 0%. This is presumably because the toner components volatilize and aggregate.

Here, the measurement conditions in FIG. 6 are as follows.
-Elapsed time since the last heating use of the fixing device: Saturation time (12 hours) or more-Usage count of the fixing device: Saturation count (10 kp) or more-Printing paper: CF80 (recommended paper basis weight 80 g / m ² ) A4 Size / printed image: When the image printing rate is 0%: Blank paper, When the image printing rate is 20%: BAM emission measurement color chart (see BAM regulations)
・ Single-sided printing ・ Fixing temperature: 180 ℃
・ Outside air temperature: 23 ℃
FIG. 7 is a diagram showing the correlation between the outside air temperature and the UFP generation amount. FIG. 7 shows a case where the image printing rate is 20% for single-sided printing (A in FIG. 7) and a case where the image printing rate is 20% for double-sided printing (B in FIG. 7). The chamber temperature at the start of printing on the horizontal axis is an actual measurement value obtained by measuring the outside air temperature in the chamber in which the image forming apparatus 100 is installed. The UFP number ratio on the vertical axis is a ratio when the number of UFP generation is 1 when single-sided printing, image printing rate is 20%, and the chamber temperature at the start of printing is 23 ° C.

As shown in FIG. 7, it can be seen that in any case, the amount of UFP generated increases as the outside air temperature decreases. This is considered to be because when the outside air temperature is lowered, when the gas generated in the fixing device is discharged from the duct 131 to the outside of the apparatus, it is rapidly cooled and easily aggregated.
Also, as shown in FIGS. 6 and 7, it can be seen that the UFP generation amount of double-sided printing is higher than the UFP generation amount of single-sided printing. This is because, in double-sided printing, when the paper whose surface is heated and fixed returns through the conveyance path near the fixing device 110 to print the back surface, the temperature in the duct 131 rises due to the heat of the paper, and thus agglomeration occurs. This is considered to be difficult.

The measurement conditions in FIG. 7 are as follows.
-Elapsed time since the last heating use of the fixing device: Saturation time (12 hours) or more-Usage count of the fixing device: Saturation count (10 kp) or more-Printing paper: CF80 (recommended paper basis weight 80 g / m ² ) A4 Size / printed image: 20% image printing rate: BAM emission measurement color chart (see BAM regulations)
Fixing temperature: 180 ° C
FIG. 8 is a diagram illustrating the correlation between the elapsed time from the end of the previous heating use of the fixing device 110 and the amount of UFP generated. It can be seen that the amount of UFP generated increases as the elapsed time on the horizontal axis increases. This is a measured value measured using a clock. The UFP number ratio on the vertical axis is a ratio when the number of UFP generation is 1 when the elapsed time is equal to or longer than the saturation time (12 hours).

As shown in FIG. 8, it can be seen that the amount of UFP generated increases as the elapsed time becomes longer, and saturates in about 12 hours. This is considered to be because the UFP generation amount transiently increases with the passage of time, but becomes a balanced state after a certain period of time and the UFP generation amount becomes stable.
Here, the measurement conditions in FIG. 8 are as follows.
-Fixing device usage count: Saturation count (10 kp) or more-Printing paper: CF80 (recommended paper, basis weight 80 g / m ² ) A4 size-Printed image: Image printing rate 20%: Color chart for BAM emission measurement (BAM regulations) reference)
・ Single-sided printing ・ Fixing temperature: 180 ℃
・ Outside air temperature: 23 ℃
FIG. 9 is a diagram illustrating a correlation between the usage count of the fixing device 110 and the UFP generation amount. The number on the horizontal axis is a numerical value of a counter built in the image forming apparatus 100. The UFP number ratio on the vertical axis is a ratio when the number of UFP generation is 1 when the usage count is equal to or greater than the saturation count (10 kp).

  As shown in FIG. 9, it can be seen that the amount of UFP generated increases as the number of sheets increases, and saturates at about 10,000 sheets. This is because low molecular siloxane contained in silicon rubber volatilizes and decreases over time due to heat during fixing heating, but low molecular siloxane is newly generated due to thermal degradation of silicon rubber. Although the UFP generation amount increases transiently, it is considered that the UFP generation amount becomes stable after a certain period of time and the equilibrium state is reached.

Here, the measurement conditions in FIG. 9 are as follows.
・ Elapsed time since the last heating use of the fixing device: Saturation time (12 hours) or more ・ Printing paper: CF80 (recommended paper basis weight 80 g / m ² ) A4 size ・ Printed image: 20% image printing rate: BAM emission Color chart for measurement (see BAM regulations)
・ Single-sided printing ・ Fixing temperature: 180 ℃
・ Outside air temperature: 23 ℃
FIG. 10 is a diagram illustrating an example of a method for estimating the generation amount of UFP.

(1) It is determined whether single-sided printing or double-sided printing (step S1).
(2) In the case of single-sided printing, an estimated value of the amount of UFP that will occur under standard conditions in single-sided printing is acquired as the standard amount of single-sided printing (step S2).
(3) In the case of double-sided printing, an estimated value of the amount of UFP that will occur under standard conditions in double-sided printing is acquired as the standard amount of double-sided printing (step S3).

Here, the standard conditions are an image printing rate of 0%, an elapsed time from the end of the last heating use of the fixing device is a saturation time (12 hours) or more, a usage count of the fixing device is a saturation count (10 kp) or more, an image The printing rate is 20% and the outside air temperature is 23 ° C.
When Tf is a fixing set temperature, A and B are constants, and e is a base of natural logarithm (Napier number), the standard generation amount Ub in the case of single-sided printing is approximately given by the following equation.
Ub = Ae ^B・^Tf
Here, the constants A and B are obtained by changing the fixing temperature and measuring the amount of UFP generated in an actual device using a particle counter or the like when the image printing rate of single-sided printing is 0%. Based on the value, it can be determined by drawing an exponential approximation curve.

Similarly, when Ub is the standard generation amount, Tf is the fixing set temperature, C and D are constants, and e is the base of the natural logarithm (Napier number), the standard generation amount for duplex printing is approximately: It is given by the formula.
Ub = Ce ^D · ^Tf
Here, the constants C and D are measured when the fixing temperature is changed and the amount of UFP generated in an actual device is measured using a particle counter or the like when the image printing rate of double-sided printing is 0%. Based on the value, it can be determined by drawing a known exponential approximation curve.

  The fixing set temperature is one of the design parameters, and is set in advance for each device and is controlled so as to reach a predetermined temperature, so that it does not fluctuate in principle. Therefore, since it is not necessary to calculate the standard generation amount for the fixing set temperature in the same device every time, the standard generation amount is stored for single-sided printing and double-sided printing, and the matching one is read out. May be used.

Also, an estimated value of the amount of UFP generated in either one-sided printing or double-sided printing is stored as a standard generated amount, and the standard amount of UFP generated between single-sided printing and double-sided printing is stored. If the estimated value difference is stored, the estimated value of the UFP generation amount of one UFP can be increased or decreased based on the difference to obtain the other standard generation amount, and substantially the same processing is performed. Can be made. Specifically, the estimated value of the UFP generation amount in single-sided printing is stored as the standard generation amount, and in the case of double-sided printing, the standard generation amount may be reduced. Alternatively, the estimated value of the UFP generation amount in double-sided printing may be stored as the standard generation amount, and in the case of single-sided printing, the standard generation amount may be increased.
(4) The standard generation amount is increased or decreased based on the image printing rate (step S4).

When α is a variable, an estimated value U1 of the UFP generation amount that is increased or decreased based on the image printing rate is given by the following equation.
U1 = α · Ub
Here, the value of the variable α is determined using a first table created by prediction based on the correlation between the image printing rate and the UFP generation amount shown in FIG.

FIG. 11 is a diagram illustrating an example of the first table.
According to FIG. 11, since the value of the variable α increases as the image printing rate increases, the control unit 140 increases the estimated value of the UFP generation amount when the image printing rate is higher than the standard condition. I will let you. The control unit 140 may decrease the estimated value of the UFP generation amount when the image printing rate is lower than the standard condition.
(5) The standard generation amount is increased or decreased based on the elapsed time from the end of the previous heating use and the usage count (step S5).

When β and γ are variables, an estimated value U2 of the amount of UFP generated that is increased or decreased based on the elapsed time from the end of the previous heating use and the usage count is given by the following equation.
U2 = β · γ · Ub
Here, the value of the variable β is determined using a second table created by prediction based on the correlation between the elapsed time from the end of the previous heating use and the amount of UFP generation shown in FIG.

FIG. 12 is a diagram illustrating an example of the second table.
According to FIG. 12, since the value of the variable β is large when the elapsed time from the end of the previous heating use is between 0 and 12.1h and is constant above 12.1h, the control unit 140 When the elapsed time from the previous heating use of the fixing device is shorter than (12.1h (12 hours 6 minutes) or more), the estimated value of the UFP generation amount is decreased. Note that the control unit 140 may increase the estimated value of the UFP generation amount when the elapsed time from the previous heating use of the fixing device is longer than the standard condition.

Here, the value of the variable γ is determined using a third table created by prediction based on the correlation between the use count and the UFP generation amount shown in FIG.
FIG. 13 is a diagram illustrating an example of the third table.
According to FIG. 13, the value of the variable γ increases when the usage count is between 0 and 8.1 kp, and is constant at 8.1 kp or more. If the usage count of the fixing device is smaller than the above), the estimated value of the UFP generation amount is decreased. Note that the control unit 140 may increase the estimated value of the amount of UFP generated when the usage count of the fixing device is larger than the standard condition.
(6) The standard generation amount is increased or decreased based on the paper size (step S6).

When δ is a variable, an estimated value U3 of the UFP generation amount that is increased or decreased based on the image printing rate is given by the following equation.
U3 = δ · U2
Here, the value of the variable δ is determined by using the fourth table created by actual measurement by the actual machine.

FIG. 14 is a diagram illustrating an example of the fourth table.
(7) It is determined whether single-sided printing or double-sided printing (step S7).
(8) In the case of single-sided printing, the standard generation amount in single-sided printing is increased or decreased based on the outside air temperature (step S8).
When Ta is the outside air temperature and E and F are constants, the estimated value U4 of the UFP generation amount in the case of single-sided printing that is increased or decreased based on the outside air temperature is approximately given by the following equation.
U4 = U3 × ((E · Ta + F) / (E · 23 + F))
Here, the constants E and F can be determined by drawing a linear line using the least square method or the like based on the correlation between the outside air temperature and the UFP generation amount shown in FIG.
(9) In the case of duplex printing, the standard generation amount in duplex printing is increased or decreased based on the outside air temperature (step S9).

When Ta is the outside air temperature and G and H are constants, the estimated value U4 of the amount of UFP generated in double-sided printing that is increased or decreased based on the outside air temperature is approximately given by the following equation.
U4 = U3 × ((G · Ta + H) / (G · 23 + H))
Here, the constants G and H can be determined by drawing a linear line using the least square method or the like based on the correlation between the outside air temperature and the UFP generation amount shown in FIG.

According to FIG. 7, the lower the outside air temperature, the larger the amount of UFP generated. Therefore, the controller 140 increases the estimated value of the amount of UFP generated when the outside air temperature is lower than the standard condition. Thus, when the outside air temperature is higher than the standard condition, the estimated value of the UFP generation amount is decreased.
In this embodiment, UFP is based on all of the paper size, double-sided printing or single-sided printing, the image printing rate, the elapsed time since the last heating use of the fixing device, the usage count of the fixing device, and the outside air temperature. However, it is possible to obtain the effect of improving the accuracy of the UFP generation amount only by increasing or decreasing the standard generation amount of UFP based on at least one of them.

  As described above, according to the present embodiment, since the number of UFPs can be estimated according to the fixing temperature and other parameters, the number of UFPs can be known without using a measuring instrument such as a particle counter. it can. Further, when almost no UFP is generated, it is possible to control the UFP not to be reduced, or to operate in the energy saving mode and limit the ability to reduce the ultrafine particles. Energy consumption can be reduced.

  Note that a program that allows a computer to execute an operation as in this embodiment is recorded on a computer-readable recording medium, and this recording medium can be distributed and traded. In addition, the program may be distributed through a network or the like, for example, and may be traded, or may be displayed on a display device, printed, and presented to a user.

  Here, the computer-readable recording medium includes, for example, a removable recording medium such as a floppy disk, CD, MO, DVD, and memory card, and a fixed recording medium such as a hard disk and a semiconductor memory, and the like. It is not something.

  The present invention can be widely applied to image forming apparatuses such as a copying machine, a printer, a FAX, and a printer multifunction peripheral. According to the present invention, wasteful energy consumption can be suppressed without using a measuring instrument such as a particle counter, and its industrial utility value is extremely high.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 110 Fixing apparatus 120 UFP reduction part 121 Heater 122 Collection filter 123 Movable valve 130 Exhaust part 131 Duct 132 Fan 140 Control part

Claims (11)

A fixing device that may be accompanied by generation of ultrafine particles during driving;
Reducing means for reducing the amount of ultrafine particles released outside the machine;
Control means for controlling the reduction means based on the estimated value of the generation amount of ultrafine particles,
The control means includes
Estimate the amount of ultrafine particles that would occur under standard conditions at a preset fixing temperature, paper size, single-sided printing or double-sided printing, image printing rate, and completion of previous heating use of the fixing device An image forming apparatus that increases or decreases based on at least one of an elapsed time from the time, a usage count of the fixing device, and an outside air temperature. The control means includes
The image forming apparatus according to claim 1, wherein when the estimated value of the generation amount exceeds a predetermined value, the reduction unit is controlled to reduce ultrafine particles. The control means includes
The image forming apparatus according to claim 1, wherein in the case of single-sided printing, the estimated value of the generated amount is increased compared to the case of double-sided printing. The control means includes
When the image printing rate is higher than the standard condition, the estimated value of the generated amount is increased, or when the image printing rate is lower than the standard condition, the estimated value of the generated amount is The image forming apparatus according to claim 1, wherein the image forming apparatus is reduced. The control means includes
When the elapsed time from the end of the previous heating use of the fixing device is longer than the standard condition, the estimated value of the generated amount is increased, or the previous time of the fixing device is exceeded than the standard condition. The image forming apparatus according to claim 1, wherein the estimated value of the generated amount is decreased when the elapsed time from the end of heating use is short. The control means includes
When the usage count of the fixing device is larger than the standard condition, the estimated value of the generation amount is increased, or when the usage count of the fixing device is smaller than the standard condition, The image forming apparatus according to claim 1, wherein the estimated amount of generation is reduced. The control means includes
When the outside air temperature is lower than the standard condition, the estimated value of the generated amount is increased, or when the outside temperature is higher than the standard condition, the estimated value of the generated amount is decreased. The image forming apparatus according to claim 1. The image forming apparatus further includes:
An exhaust means for taking in the gas generated in the fixing device into the duct and discharging the taken-in gas out of the machine from the duct;
The reducing means is
8. The image forming apparatus according to claim 1, wherein the amount of ultrafine particles released to the outside of the machine is reduced by heating the inside of the duct. 9. The reducing means is
The output can be varied in multiple steps or steplessly,
The control means includes
The image forming apparatus according to claim 8, wherein an output of the reduction unit is changed based on an estimated value of the generation amount of ultrafine particles. The image forming apparatus further includes:
An exhaust means for taking in the gas generated in the fixing device into the duct and discharging the taken-in gas out of the machine from the duct;
The reducing means is
The image forming apparatus according to claim 1, wherein the amount of ultrafine particles released to the outside of the apparatus is reduced by passing the gas in the duct through a collection filter. The image forming apparatus further includes:
An exhaust means for taking in the gas generated in the fixing device into the duct and discharging the taken-in gas out of the machine from the duct;
The reducing means is
The amount of ultrafine particles released to the outside is reduced by charging the ultrafine particles in the duct and passing the gas in the duct through an electrostatic filter. 2. The image forming apparatus according to item 1.

Images