JP2017037156A - Exhaust system and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce ultra fine particles (UFPs) to be discharged.SOLUTION: An exhaust system comprises: a fan 62 that discharges the air heated by a fixing unit 40 that heats a toner image held on a sheet P conveyed to fix the toner image onto the sheet P; a fan 61 that discharges the air on the downstream of the fixing unit 40 in a direction of conveying the sheet P; and an exhaust control part that controls exhausting capacity per unit time of at least one of the fan 61 and fan 62.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an exhaust device and an image forming apparatus.

  In recent years, regulations on the discharge of fine particles having a particle size of 0.1 μm or less, called UFP (Ultra Fine Particle), have been strengthened, and countermeasures have been demanded.

  Here, in Patent Document 1, when the fixing unit is cold, the fixing exhaust fan is driven at a higher speed than usual so that a large amount of UFP generated is not diffused into the apparatus and surely passes through the filter. By exhausting, it has been proposed to reduce the amount of UFP discharged from the image forming apparatus main body without lowering productivity and image quality.

  In Patent Document 2, a determination value is acquired based on the number of ultrafine particles detected by the fixing particle detection unit. When the determination value is equal to or less than a predetermined threshold, the normal mode is performed, and the determination value is When the predetermined threshold value is exceeded, the fine particle countermeasure mode is performed, and the duct is connected to the first filter in the normal mode, and to the second filter with finer eyes in the fine particle countermeasure mode. Proposed.

  Patent Document 3 has a normal fixing temperature control mode and an ultrafine particle generation temperature control mode. In the ultrafine particle generation temperature control mode, the surface temperature of the fixing roller is higher by 10 ° C. or more than the upper limit fixing temperature. It has a heating state for maintaining the ultrafine particle control upper limit temperature and a heating stop state for stopping the heating of the fixing roller. The heating state and the heating stop state are alternately repeated to remove volatile organic substances from the fixing roll by heat treatment. It has been proposed.

JP, 2014-044238, A JP 2012-128013 A JP 2012-058658 A

  It is an object of the present invention to provide an exhaust apparatus and an image forming apparatus that suppress UFP discharge as compared with an apparatus in which the exhaust capabilities of both the first exhaust section and the second exhaust section are fixed.

According to a first aspect of the present invention, there is provided a first exhaust unit that exhausts air heated by a fixing device that heats a powder image held on a conveyed sheet and fixes the powder image on the sheet;
Exhaust capacity per unit time of a second exhaust unit that exhausts air downstream from the fixing device in the sheet conveyance direction, and at least one of the first exhaust unit and the second exhaust unit. An exhaust system comprising: an exhaust control unit that performs control to decrease.

  According to a second aspect of the present invention, in the exhaust device according to the first aspect, the second exhaust unit is an exhaust unit that exhausts air heated by the sheet after passing through the fixing unit.

  According to a third aspect of the present invention, the exhaust control unit relatively suppresses the exhaust capacity per unit time of the at least one exhaust unit when the fixing temperature is relatively low according to the fixing temperature in the fixing device. The exhaust device according to claim 1, wherein control is performed. It is.

  According to a fourth aspect of the present invention, the exhaust control unit performs control to relatively suppress the exhaust capacity per unit time of the at least one exhaust unit when the environmental temperature is relatively low according to the environmental temperature. The exhaust device according to any one of claims 1 to 3, wherein

Claim 5
An image forming unit that holds the powder image on a sheet that has been conveyed by forming a powder image;
A fixing device that holds the powder image and heats the powder image on the paper that has been conveyed to fix the powder image on the paper;
An image forming apparatus comprising: the exhaust apparatus according to claim 1.

  According to the exhaust apparatus of claim 1 and the image forming apparatus of claim 5, it is possible to suppress the discharge of UFP as compared with an apparatus in which the exhaust capabilities of both the first exhaust section and the second exhaust section are fixed. it can.

  According to the exhaust device of the second aspect, it is possible to effectively suppress the discharge of UFP generated after fixing.

  According to the third and fourth aspects of the present invention, it is possible to suppress the discharge of UFP while suppressing an unnecessary temperature increase or decrease of the fixing device.

1 is a schematic configuration diagram of a printer as an embodiment of an image forming apparatus of the present invention. It is the schematic diagram which showed the flow of the air by a fan in the printer shown in FIG. It is the figure which showed the number and volume of UFP contained in the air exhausted from the printer shown in FIG. FIG. 2 is a diagram illustrating an example of a fan rotation control sequence in the printer illustrated in FIG. 1.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram of a printer as an embodiment of the image forming apparatus of the present invention. The printer 1 is connected to an external device (not shown) such as an external scanner or a computer. An image signal is input from the connected external device, and an image based on the input image signal is placed on the paper P. It is an apparatus to form.

  The printer 1 includes an image forming unit 10, and the image forming unit 10 includes a photoconductor 11. The photosensitive member 11 receives a driving force and rotates in the direction of arrow A to form an electrostatic latent image on the surface thereof, and further, a toner image is formed by development.

  Further, around the photoreceptor 11, a charger 12, an exposure device 13, a developing device 14, a transfer device 15, and a cleaner 16 are provided.

  The charger 12 uniformly charges the surface of the photoconductor 11.

  The exposure device 13 irradiates the uniformly charged photoconductor 11 with exposure light 131 modulated based on the image signal to form an electrostatic latent image on the photoconductor 11.

  The developing device 14 develops the electrostatic latent image formed on the photoconductor 11 with toner to form a toner image on the photoconductor 11.

  A toner cartridge 141 containing toner is provided above the developing unit 14. When the toner in the developing device 14 is consumed by the development, an amount of toner corresponding to the consumption is replenished from the toner cartridge 141 to the developing device 14. The toner cartridge 141 is configured to be detachable. When the toner cartridge 141 becomes empty, the toner cartridge 141 is replaced with a new toner cartridge 141 containing toner.

  The transfer unit 15 transfers the toner image formed on the photoconductor 11 onto the paper P conveyed to a position sandwiched between the transfer unit 15 and the photoconductor 11.

  The cleaner 16 removes toner and the like remaining on the photoconductor 11 after transfer.

  The paper P is stored in a state of being stacked on a paper tray 21 provided in the lower part of the printer 1. The paper tray 21 is detachable. When the paper tray 21 becomes empty or is replaced with a paper P of a different size or type, the paper tray 21 is once taken out, replenished with the paper P, or replaced with the paper P and mounted again. Is done.

  In forming an image, the uppermost sheet P stored in the sheet tray 21 is fed out by the pick-up roll 31 and is separated into only one sheet by the separating roll 32, and the separation is performed. The single sheet P thus conveyed is conveyed in the direction of arrow B. When the leading edge of the paper P reaches the timing adjustment roll 34, the paper P is temporarily stopped. Then, the paper P that has reached the timing adjustment roll 34 has the toner image formed on the photoconductor 11 at the timing at which the toner image formed on the photoconductor 11 reaches the position of the transfer device 15 due to the rotation of the photoconductor 11 in the arrow A direction. The toner is further fed out by the timing adjusting roll 34 so as to reach the position, and the toner image on the photoconductor 11 is transferred onto the paper P by the action of the transfer unit 15. The sheet P that has received the transfer of the toner image is further transported in the direction of arrow C by the transport belt 35 and passes through the fixing device 40. The fixing device 40 includes a heating roll 41 and a pressure roll 42. The heating roll 41 is provided with a heater 411, and the temperature of the heating roll 41 is controlled. The heating roll 41 and the pressure roll 42 rotate in the directions of arrows J and K, respectively, and heat and press the paper P that is passing through, whereby the toner image on the paper P is fixed on the paper P. Is done. The paper P that has passed through the fixing device 40 is further conveyed in the direction of arrow D, and is sent out onto a paper discharge tray 37 by a paper discharge roll 36.

  Further, in the subsequent stage of the printer 1, a device for stocking the paper P sent out by the printer 1, a device for punching the paper P sent out from the printer 1, a device for binding by a stapler, etc. Various post-processing devices (not shown) can be connected. When a post-processing device is connected to the printer 1, the paper P sent out from the printer 1 is further subjected to processing according to the connected post-processing device.

  In addition, the printer 1 includes a control unit 50 that controls each unit, and the control unit 50 controls the above-described operation.

  Further, the printer 1 is provided with a temperature sensor 51 that measures the temperature inside the printer 1. The temperature measurement result of the temperature sensor 51 is also transmitted to the control unit 50 and used for control.

  Here, the sheet P immediately after passing through the fixing device 40 is in a considerably high temperature state due to the effect of heating by the fixing device 40, and in the direction of arrow D until it is sent out of the printer 1 by the paper discharge roll 36. The air inside the printer 1 is heated while being conveyed. Therefore, a fan 61 is provided here. When the fan 61 is operated, the air warmed by the paper P flows in the upward direction indicated by the arrow U and is sucked into the fan 61, and is exhausted to the outside of the printer 1 in the arrow S direction by the fan 61. Thereby, the temperature rise in the printer 1 is suppressed. The fan 61 is a fan having a variable rotational speed, and the controller 50 controls the rotational speed and on / off of the rotation.

  FIG. 2 is a schematic diagram showing the air flow by the fan in the printer shown in FIG.

  2 shows that two fans 61 also shown in FIG. 1 are arranged in the direction perpendicular to the paper surface in FIG. 1, that is, in the depth direction of the printer 1. Each of these two fans 61 is a fan that causes the air in the room behind the fixing device 40 to flow in the directions of the arrows U and S shown in FIG.

  Further, another fan 62 is provided on the back side of the fixing device 40 (the back side in the direction perpendicular to the paper surface of FIG. 1). The fan 62 is a fan for suppressing a temperature rise in the printer 1 due to the heating roll 41 constituting the fixing device 40. When this fan 62 is operated, a flow in the direction of arrow R1 is created in the air in the fixing device 40, and further, the air is exhausted outside the printer 1 in the direction of R2. The fan 62 is also a fan having a variable rotational speed, and the rotational speed and on / off of the rotation are controlled by the control unit 50 shown in FIG.

  Here, a dotted arrow V is shown in FIG. The room in which the fan 61 is in charge of exhaust and the interior of the fixing device 40 in which the fan 62 is in charge of exhaust are not completely separated. Temporarily, the fan 61 is stopped and only the fan 62 is stopped. , The air flow in the direction of the arrow V is generated instead of the exhaust in the direction of the arrow S, and the air in the room where the fan 61 shares the exhaust is also combined with the air in the fixing device 40 and is in the direction of the arrow R1. , R2 direction and exhausted from the printer 1.

  On the other hand, if only the fan 61 is operated and the fan 62 is stopped, an air flow in the direction opposite to the arrow V occurs instead of the exhaust in the directions of the arrows R1 and R2, and the inside of the fixing device 40 The air is also exhausted from the printer 1 in the direction of arrow S together with the air in the room where the fan 61 is in charge of exhausting.

  FIG. 3 is a diagram showing the number and volume of UFPs contained in the air exhausted from the printer shown in FIG.

3A is a graph when both the fans 61 and 62 shown in FIG. 2 are operated. FIG. 3B is a graph when the fan 61 is stopped and only the fan 62 is operated. It is a graph. 3A and 3B, (1) represents the number of UFPs, and (2) represents the volume of UFP (the sum of the volumes of each individual). Furthermore, the left vertical axis represents the number per 1 cm ³ , and the right vertical axis represents the volume per 1 cm ³ (mm ³ ).

  3 (A) (2) and FIG. 3 (B) (2) are compared with FIG. 3 (B) in which the fan 61 is stopped compared to FIG. 3 (A) in which both fans 61 and 62 are operated. It can be seen that the volume of UFP in the air discharged from the printer 1 is reduced. This is presumably because the total exhaust amount from the printer 1 was reduced by stopping the fan 61.

  Next, FIG. 3 (A) (1) and FIG. 3 (B) (1) are compared. Then, it can be seen that the number of UFPs in the air exhausted from the printer 1 is significantly smaller than the method of reducing the volume. That is, the number of UFPs is greatly reduced compared to the volume of UFP. When the fan is stopped, the air flow in the direction of arrow V shown in FIG. 2 is generated, and the air in the room where the fan 61 shared the exhaust air is generated. As a result of being integrated with the air in the fixing device 40, the density of UFP in the fixing device 40 is increased, and it is considered that the UFPs are coupled to each other. A problem with UFP discharge is the number of UFPs. If the phenomenon shown in FIG. 3 is used, the number of UFP discharges can be reduced.

  FIG. 4 is a diagram showing an example of a fan rotation control sequence in the printer 1 shown in FIG.

  FIG. 4A shows a control sequence of the fan 62 that is in charge of exhaust in the fixing device 40. FIG. 4B shows a control sequence of the fan 61 that is in charge of exhausting the room in the rear stage of the fixing device 40.

  As shown in FIG. 4A, the fan 62 that is in charge of exhausting the air in the fixing device 40 is slow at a power of 50% of rated power during standby before power-on to start printing (image formation). Rotation is performed, and rotation is performed with rated (100%) power after the start of printing (image formation). When the current printing is completed and the printer returns to the standby state, it rotates again with 50% of the rated power. This is because the energization of the heater 411 of the heating roll 41 of the fixing device 40 is restricted during standby, and the temperature of the heating roll 41 is kept at a standby temperature lower than the temperature at the time of printing, so it is necessary to cool strongly. Because there is no.

  In addition, as shown in FIG. 4B, the fan 61 that is in charge of exhausting the room subsequent to the fixing device 40 is in the standby state of the printer 1 measured by the temperature sensor 51 (see FIG. 1). When the internal temperature is higher than the threshold value, low speed rotation is performed with 50% of the rated power. On the other hand, when the internal temperature of the printer 1 is lower than the threshold, the printer 1 remains stopped.

  The fan 61 rotates intermittently with rated (100%) power during printing from the start of printing to the stop of printing. In this intermittent rotation, the ratio between the rotation time and the rotation stop time may be fixedly determined, but depends on the temperature of the heating roll 41 or the amount of electric power supplied to the heater 411. The lower the temperature or the smaller the amount of power, the shorter the rotation time may be controlled. Alternatively, according to the temperature in the printer 1 measured by the temperature sensor 51, the lower the temperature, the shorter the rotation time may be controlled.

  In this way, if the rotation time of the fan 61 is suppressed, an air flow in the direction of arrow V shown in FIG. 2 is generated while the fan 61 is stopped, and the number of UFP discharged can be reduced.

  In this example, the fan 61 is intermittently rotated during printing. However, the rotation itself is continuous and the rotation speed is reduced from the rated power (10%). Also by controlling, a certain amount of airflow in the direction of arrow V is always generated, and the UFP reduction effect can be obtained.

  Here, an example is shown in which the rotation of the fan 61 is mainly controlled to reduce UFP. However, even if the rotation of the fan 62 is controlled to generate an air flow in the direction opposite to the arrow U shown in FIG. Good.

  In addition, although the single printer 1 is illustrated here, when the post-processing device is connected to the printer 1, the fan built in the post-processing device also rotates in the same manner as the fan 61. You may control.

  Furthermore, although an example in which the present invention is applied to the monochrome printer that forms one color image shown in FIG. 1 is shown here, the present invention is a color printer that forms a color image using a plurality of color toners. It can be applied as it is.

DESCRIPTION OF SYMBOLS 1 Printer 10 Image formation part 40 Fixing device 50 Control part 51 Temperature sensor 61, 62 Fan

Claims (5)

A first exhaust unit that exhausts air heated by a fixing device that heats the powder image held on the conveyed paper and fixes the powder image on the paper;
Exhaust capacity per unit time of a second exhaust unit that exhausts air downstream from the fixing device in the sheet conveyance direction, and at least one of the first exhaust unit and the second exhaust unit. An exhaust system comprising: an exhaust control unit that performs control so as to decrease.   2. The exhaust device according to claim 1, wherein the second exhaust unit is an exhaust unit that exhausts air heated by the sheet after passing through the fixing unit.   The exhaust control unit performs control to relatively suppress the exhaust capacity per unit time of the at least one exhaust unit when the fixing temperature is relatively low according to the fixing temperature in the fixing device. The exhaust device according to claim 1 or 2, wherein   The exhaust control unit performs control to relatively suppress the exhaust capacity per unit time of the at least one exhaust unit when the environmental temperature is relatively low according to the environmental temperature. The exhaust device according to any one of claims 1 to 3. An image forming unit that holds the powder image on a sheet that has been conveyed by forming a powder image;
A fixing device that holds the powder image and heats the powder image on the paper that has been conveyed to fix the powder image on the paper;
An image forming apparatus comprising: the exhaust device according to claim 1.

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