JP2012123289A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus having a blowing device capable of preventing faults caused by water droplets attached to blowing means which is a part located in the vicinity of a fixing device.SOLUTION: An image forming apparatus has a fixing device which thermally processes a transfer material after transferring while conveying it through a nip part formed by a first fixing member and a second fixing member and a blowing device. The blowing device has: blowing means; a blowing duct for blowing an air flow generated by operating the blowing means to the transfer material after passing through the nip part of the fixing device; a connection duct which is connected in a communicable manner to the blowing duct and guides the air sent out by the blowing means to the inside of the blowing duct; and a switching member for switching between a communicating state and a non-communicating state of the blowing duct and the connection duct. The switching member goes into the communicating state when the blowing means is operating and into the non-communicating state when the blowing means is not operating.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, or a multi-function machine that produces a toner image using an electrophotographic system.

  For example, the surface of the photosensitive drum is charged, exposed and developed to produce a toner image according to the document or image data, and then the toner image is transferred to a transfer material such as paper or once, an intermediate transfer member An image forming apparatus that performs secondary transfer to a transfer material after transfer to a transfer material is well known.

  Such an image forming apparatus includes, for example, a first fixing roller having a built-in heating source, and a second fixing roller having no built-in heating source and rotating while being in pressure contact with the first fixing roller ( A fixing device). Then, while the transfer material after the transfer is nipped at the nip portion by both fixing rollers, heating and pressurizing action are simultaneously applied to the transfer material to fix the toner image on the transfer material.

  However, in the case of a fixing unit configured to apply a heating and pressing action while sandwiching and transporting the transfer material, the transfer material may not be separated from the fixing unit due to environmental conditions or the amount and type of the transfer material. . Therefore, conventionally, an appropriate separating means has been arranged on the outlet side of the fixing means.

  As a separation means (separation device), a configuration using a separation claw made of resin or film as a factor can be considered, but in recent years, an air separation means has been proposed and implemented as a useful means.

  In the first proposal using the air separating means, for example, the peeling guide plate is disposed close to the rotating body such as the fixing roller so as to face the surface of the rotating body. And it is the method of discharging pulsed compressed air toward the gap | interval formed with the surface of the rotary body and the peeling guide plate (for example, refer patent document 1). This method does not damage the rotating body such as the fixing roller and the toner image, and the compressed gas flow is rectified in the gap described above, and the compressed gas is discharged efficiently, so that the compressed gas is discharged continuously. It is possible to make it into a pulse shape without taking it.

  In the second proposal, a peeling guide plate is arranged close to the downstream side of the fixing unit, and the surface of the rotating member constituting the fixing unit is peeled off during the time when the leading edge of the transfer material passes through the nip portion of the transfer unit. High pressure air is blown from the gap formed by the guide plate. Moreover, it is the method of blowing the air of low pressure at other time (for example, refer patent document 2). This method does not damage the rotating body such as the fixing roller. The blown air is blocked by the nip and flows along the axial direction of the fixing roller, for example, so that high-humidity air staying in the paper discharge unit can be discharged out of the fixing device, and condensation in the paper discharge unit can also occur. Can be removed. As a result, condensation of water droplets adhering to the fixing device and its nearby components is released from adhering to the recording material and degrading the image quality.

Japanese Patent Application Laid-Open No. 2004-212954 JP 2007-86132 A

  However, in order to prevent water droplets from adhering to parts in the vicinity of the fixing device, low-pressure air controlled through a solenoid valve is blown from a blowing means such as a compressor at a time other than when the recording material is separated. It is necessary to turn on. In other words, while the continuous fixing process is performed, and for a predetermined time after the final fixing process is finished (that is, while the staying air in the paper discharge unit is discharged outside the apparatus), The blowing means needs to blow air through the nozzle, and there is room for improvement in terms of effective use of energy. The present invention provides an image forming apparatus equipped with an air blowing device capable of preventing problems caused by water droplets adhering to the air blowing means, which is a component in the vicinity of the fixing device, without the air blowing means continuing to blow air. To provide an apparatus.

  The image forming apparatus according to the present invention can be achieved by the following constitutional requirements.

1. An image carrier;
A transfer member for transferring a toner image formed on the image carrier to a transfer material;
A fixing device that heat-treats the transferred transfer material while conveying it through a nip formed by a first fixing member and a second fixing member;
An air blowing device;
In an image forming apparatus having
The air blowing device is
Air blowing means;
A blowing duct having a blowing portion that blows an air flow generated by driving the blowing unit toward a transfer material that has passed through a nip portion of the fixing device;
A connection duct connected to the blowing duct so as to be able to communicate and guiding the air sent out by the blowing means into the blowing duct;
A switching member that switches between a communication state in which the blowing duct and the connection duct communicate with each other and a non-communication state in which the blowing duct and the connection duct do not communicate with each other;
With
The switching member takes the communication state when the air blowing means is driven, and takes the non-communication state when the air blowing means is not driven.
An image forming apparatus.

2. The blowing duct has a discharge part that discharges air entering from the blowing part above the blowing part,
2. The image forming apparatus as described in 1 above.

3. The switching member takes the communication state when the air blowing means is driven, and closes the discharge portion.
3. The image forming apparatus as described in 2 above.

4). The connection duct and the blowing duct are arranged so that an air flow generated by driving the blowing means flows in a horizontal direction at a communication portion between the connection duct and the blowing duct.
4. The image forming apparatus according to any one of items 1 to 3, wherein:

5. A discharge duct connected to the blowing duct so as to enter the blowing section of the blowing duct and guide the air discharged from the discharge section to the outside of the image forming apparatus;
5. The image forming apparatus according to any one of 1 to 4, wherein:

6). The blowing duct and the discharge duct are arranged so that the air discharged from the discharge portion flows in a vertical direction at the boundary between the blowing duct and the discharge duct.
6. The image forming apparatus as described in 5 above.

7). A support member that rotatably supports the switching member;
An elastic member that urges the switching member in a direction to keep the blowing duct and the connection duct in the non-communication state,
The switching member is rotated by an air flow generated by driving the air blowing means, and takes the communication state.
7. The image forming apparatus according to any one of 1 to 6, wherein:

8). A drive member for driving the switching member;
Control means for driving and controlling the drive member,
The control means controls the drive member based on the operating state of the blower means;
7. The image forming apparatus according to any one of 1 to 6, wherein:

  In the present invention, since the switching member prevents the water droplets from adhering to the air blowing means when the air blowing means is not driven, even if the air blowing means does not continue to blow air, the problem caused by the water droplets adhering to the air blowing means is prevented. An object of the present invention is to provide an image forming apparatus provided with an air blowing device capable of performing the above-described operation.

1 is a schematic diagram illustrating a configuration of an image forming apparatus including a digital color copying machine. It is a figure which shows one structure of a fixing means. FIG. 6 is a schematic diagram for explaining a problem caused by an atmosphere in the vicinity of a sheet discharge side of a fixing unit when a blower fan is used as a blower unit. It is a figure for explanation which shows a 1st embodiment of an air blowing device notionally. It is a figure for explanation showing the 2nd embodiment of an air blowing device notionally. It is explanatory drawing which shows 3rd Embodiment of an air blowing apparatus notionally. It is explanatory drawing which shows notionally 4th Embodiment of an air spraying apparatus. It is a figure for explanation showing the 5th embodiment of an air blowing device notionally.

  Embodiments according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus composed of a digital color copying machine.

  The image forming apparatus H shown in the figure has an automatic document feeder 1 at the top, and includes an image reading unit 2, an image forming unit 3, a belt setting unit for the belt unit 4, a paper feeding unit 5, and reverse paper ejection. A refeed unit 6, an ADU 7 that is a reverse conveying unit, and a fixing device 9 are provided.

  The automatic document feeder 1 includes a document placing table 101, a document separating unit 103, a document conveying unit 105, a document discharging unit 107, a document discharging table 109, and a document reversing unit 111. Documents (not shown) on the document table 101 are separated one by one by the document separation unit 103 and conveyed toward the image reading position via the document conveying unit 105. The document reading position is provided below the document conveying unit 105, and an image of the document is read through the slit 201 constituting the image reading unit 2, and the read document is discharged by the document discharge unit 107. It is discharged onto the table 109.

  In the double-sided image recording mode, the original on which one side has been read is sandwiched between the original reversing means 111, and then reversely conveyed by the reverse rotation of the original reversing means 111, and is again guided to the image reading position. Are discharged onto the document discharge table 109. An operation display unit 150 includes various operation buttons and a display unit. In addition to an image formation start button (print button) and a numeric keypad for setting the number of image formations, an image formation mode (single-sided mode, double-sided mode), density adjustment or Liquid crystal display selection means used for selecting the magnification change is provided. Hereinafter, for convenience of explanation, the operation display unit 150 may be simply referred to as the display unit 150.

  The image reading unit 2 is a linear shape that obtains image information by photoelectrically converting a light image formed by the slit 201, the first mirror unit 205, the second mirror unit 207, the imaging lens 209, and the imaging lens 209. Image pickup element (hereinafter referred to as CCD) 211. The image information is subjected to appropriate image processing and then temporarily stored in a memory in the control means S described later. The image information of each color read by the image reading unit 2 is sequentially extracted from the memory, and input as an electrical signal to the exposure optical system for each color.

  The image forming unit 3 forms four toner image forming units 30 of yellow (Y), magenta (M), cyan (C), and black (BK) for forming a toner image corresponding to the color separation image on an image carrier described later. (30Y, 30M, 30C, 30BK: hereinafter referred to as an image forming unit). Each image forming unit 30 includes a photosensitive drum 310 as an image carrier, a charger 320, an exposure optical system 330 as an image writing unit, a developing device 340, a transfer unit 350, a cleaning member 360, and the like. In the figure, only members constituting the yellow image forming unit are provided with reference numerals, and the other image forming units have basically the same configuration, and thus the reference numerals are omitted.

  The developing device 340 includes a developer carrying member, and stores a developer including a magnetic carrier and a non-magnetic toner (hereinafter simply referred to as toner) having a different color for each developing device. The cleaning member 360 removes the toner remaining on the photosensitive drum 310 after transfer, and the removed toner is transported to the waste toner box DT and stored. The above-described image forming units 30 are arranged in the order of yellow (Y), magenta (M), cyan (C), and black (BK) from the top along the traveling direction of one plane A of the intermediate transfer belt 401. Yes.

  The intermediate transfer belt 401 as an intermediate transfer member or an image carrier, the support rollers 405, 406, and 407 for suspending the intermediate transfer belt 401, the backup roller 410, and the like constitute the belt unit 4. Reference numeral 409 denotes a blade as a cleaning means.

  The secondary transfer mechanism unit 8 transfers the toner image carried on the intermediate transfer belt 401 onto a transfer material P (described later). As shown in the figure, the transfer mechanism 8 includes a plurality of support means (support rollers) 813 and 815 made of rollers, a press means 810 (press roller) made of rollers, and a transfer belt 800 suspended on these means. The pressing unit 810 functions as a support unit for the transfer belt 800 and is also a transfer member that keeps the pressure-bonding between the transfer belt 800 and the intermediate transfer belt 401 in cooperation with the opposing backup roller 410.

  A bias power supply (not shown) that outputs a voltage of a predetermined polarity (a polarity opposite to the charging polarity of the toner) is connected to the pressing means 810, so that the energization is controlled via the control means S (described later). It has become.

  The transport roller 830 is for feeding the transferred transfer material P to the downstream fixing device 9. The fixing device 9 has a first fixing roller 900 as a first fixing member positioned so as to be in contact with the transfer material P on the side having an unfixed toner image. The image forming apparatus further includes a second fixing roller 901 as a second fixing member that rotates while being pressed against the first fixing roller 900, and the fixing unit 90 including both the fixing members is a main component. The first fixing roller 900 incorporates a heating source (not shown) such as a halogen lamp as is well known. As described above, the fixing unit 90 composed of the fixing roller pair conveys the transfer material P by nipping (niping) the transfer material P at the nip portion (nip portion) formed by pressure bonding between the two, and using a heating source. The toner image is fixed to the transfer material P by applying a heating and pressurizing action.

  The layer structure of the fixing roller can be determined as appropriate. For example, the first fixing roller 900 can be configured to have a silicon rubber layer on a metal roller and a surface layer coated with fluorine. Further, the second fixing roller can be configured to have a silicon rubber layer on a metal roller and a surface layer made of a fluorine-based tube. As an aspect of the fixing unit, a configuration in which a roller and a belt are combined instead of the first fixing roller 900 and the second fixing roller 901 described above can be used.

  Specifically, the configuration shown in FIG. 2 can be adopted. In FIG. 2, a support roller 903 suspends a belt 908 and presses the belt 908 with the pressing roller 906 with the belt interposed therebetween. The support roller 905 is a roller with a built-in heating source L. N indicates a nip portion. The belt 908 can be configured, for example, by providing a silicon rubber layer and a fluorine-based tube as a surface layer on a polyimide substrate.

  Returning to FIG. 1, what is shown on the paper discharge side of the fixing unit 90, that is, on the downstream side of the nip portion of the fixing unit 90 with respect to the conveying direction of the transfer material P, An air blowing device 95 (synonymous with air separating means) functions as a means for preventing sticking. Further, a fixing unit discharge roller 990 is shown further downstream of the air blowing device 95. The air blowing device 95 includes a blower fan (described later) including a sirocco fan, a cross flow fan, and the like. The use of the blower fan as described above as the air flow (gas flow) generating means or the blower means is easy to handle at the time of assembly, can reduce the size of the device, simplify the configuration, and can be manufactured. There is an advantage that it is inexpensive.

  The air blowing device 95 is a duct (described later) that guides and discharges the gas flow generated by driving the blower fan to the downstream (paper discharge) side of the nip portion N of the fixing unit 90 with respect to the transfer direction of the transfer material P. including. Further, the leading end of the duct is bent toward the paper discharge side of the nip portion N. This is intended to discharge an air flow toward a portion suitable for separating the transfer material P conveyed while being stuck to the first fixing roller 900 from the first fixing roller 900, An appropriate shape can be obtained depending on the specification.

  Note that the air volume setting table is provided in an appropriate memory in the control means S, which will be described later, so that the air volume by the blower fan is selected and used according to the type and volume of the transfer material. Automatically selected from information. Although the details of the mechanical configuration of the air blowing device 95 will be described later, for example, the blower fan in the present embodiment is kept in a driving state until a series of jobs are finished, and is in a non-driving state after the job is finished. Controlled.

  The paper feed trays P1, P2, and P3 are each for storing a transfer material P such as paper. The feeding unit includes paper feed rollers 503, 513, and 523, separation rollers 506, 516, and 526, and transport rollers R1, R2, and R3. The transfer material P fed out by these rollers is transported along a paper transport path on which transport rollers R5 to R7 are disposed. The registration roller 59 is provided at a position close to the secondary transfer region 560.

  The paper discharge roller 600 is for discharging the transfer material P to the paper discharge tray 650.

  The reverse paper discharge / refeed unit 6 can reverse the transfer material P after the fixing process and discharge it outside the apparatus. In the double-sided image forming mode, the transfer material P on which the image is formed and fixed on the first surface is guided to the registration roller 59 by the conveyance rollers 610 and 620 and is fed again, so that the second transfer material P is transferred. An image is formed on the two surfaces. Note that the transfer path of the transfer material at the time of double-sided image formation is basically known and will not be described in detail because it is not directly related to the present invention.

  Based on the machine operation program, the control means S performs all controls such as control related to a series of image forming processes, paper feed control, drive control of the air blowing device, and the like. In other words, the control means S includes a CPU that performs calculation control processing, a ROM that stores various operation programs, a RAM that stores calculation result data, and the like. Then, the outputs of various sensors are taken into the CPU via the interface, and the display means, the drive means and the like are driven and controlled. F denotes an exhaust fan for discharging the air inside the apparatus to the outside of the apparatus.

  Here, the operation of the image forming apparatus having the above-described configuration will be briefly described. When the power of the image forming apparatus H is turned on and the surface temperature of the first fixing roller 900 constituting the fixing unit 90 reaches the target set temperature, the operation display unit 150 displays that image recording is possible. When the user presses an image formation start button (start button) on the operation display board 150, an image recording operation is started, and the surface of the photosensitive drum 310 that rotates counterclockwise is charged to a predetermined polarity by the charger 320. The Next, the exposure optical system 330 performs exposure corresponding to the first color signal, that is, the yellow (Y) image signal, and a latent image corresponding to the yellow (Y) image is formed on the photosensitive drum 310. Is done. The latent image is reversely developed by the developing device 340 to which a developing bias voltage is applied and converted into a yellow (Y) toner image, and then transferred onto the intermediate transfer belt 401 by the action of the transfer unit 350. Image formation with other color signals that is sequentially started after a predetermined time from the start of image formation with the first color signal is performed for each of magenta (M), cyan (C), and black (BK) by the same process as described above. This is done by the image forming unit 30.

  Each toner image on the photosensitive drum 310 formed by each image forming unit is sequentially transferred so as to overlap with an image area where a yellow (Y) toner image is present, and is superimposed on the intermediate transfer belt 401. A toner image is formed. On the other hand, the transfer material P fed by the paper feed roller 503 (513, 523) in accordance with the image forming process is stopped with the tip abutting against the registration roller 59. Then, the transfer material P is re-fed at a timing overlapping with the color toner image area on the intermediate transfer belt 401 by resuming the rotation of the registration roller 59.

  Next, the transfer material P is pressed together with the intermediate transfer belt 401 and the transfer belt 800 by the backup roller 410 and the pressing unit 810 in the secondary transfer region, and during this time, the color toner image on the intermediate transfer belt 401 is transferred onto the transfer material P. Transcribed. The transfer material P that has undergone the transfer process is separated from the intermediate transfer belt 401, and is then sandwiched between transport rollers 830, and then heated and pressurized while being sandwiched and transported by the fixing unit 90. Immediately after passing through the fixing means 90, the transfer material P is promoted to be separated from the first fixing roller 900 by an air flow of a predetermined air volume from the air blowing device 95, and then discharged by the paper discharge roller 600 in a selected form. The paper is discharged onto a paper tray 650. Such an operation is repeated until the recording of a predetermined number of images according to the original is completed. The air blowing device 95 is driven until the first transfer material P to the last transfer material P in the series of jobs are released from the nip of the fixing unit 90, and then controlled to a non-driven state.

  Next, a problem caused by an air blowing device using a blower fan as a blowing unit and an atmosphere in the vicinity of the paper discharge side of the fixing unit 90 will be briefly described with reference to FIG. 3 as a comparative example. The fixing unit 90 in the figure is the same as that shown in FIG. 2, and therefore, is given the same reference numerals and redundant description is omitted. The air blowing device 95 includes a blowing duct 952 and a blower fan 951 composed of a sirocco fan provided in the upper part thereof. An air flow (arrow) generated by driving the blower fan 951 is sent into the blowing duct 952 and passes through the nip portion of the fixing unit 90 via the blowing portion 953 to the front end portion of the transfer material P. It is blown toward. In other words, the transfer material that has been heat-treated while being nipped between the belt 908 and the pressure roller 906 formed by pressing the support roller 903 and the pressure roller 906 is then subjected to the air blowing action of the air blowing device 95. And is reliably separated from the belt 908. However, since the moisture in the transfer material P heat-treated by the fixing unit 90 evaporates, the atmosphere in the vicinity of the downstream side of the nip portion (meaning the vicinity of the fixing paper discharge portion) becomes high temperature and high humidity. Therefore, for example, when the drive of the blower fan is switched to non-drive after the transfer material P has passed through the nip portion N, high-humidity air staying in the vicinity of the paper discharge portion is blown from the blowing portion 953 into the blowing duct 952. Enters and rises, and eventually reaches the blower fan 951. On the other hand, for example, an electronic component such as a brushless motor for driving the blower fan is integrally attached to the blower fan 951, and when high humidity air is touched or dew condensation occurs, As a result, there is a problem that the normal operation of the blower fan is hindered and damaged.

  4 to 8 are explanatory views conceptually showing an embodiment of an air blowing device according to the present invention corresponding to the above-mentioned problem. FIG. 4 shows a first embodiment of the air blowing device. The configuration of the fixing means in the figure is the same as that shown in FIGS. 2 and 3, and the reference numerals are unified. Further, the same members as those already described in the air blowing device 95 are also denoted by the same reference numerals. In the drawing, a two-dot chain line indicates a side plate (no reference) for supporting the fixing unit 90 and the like. The connection duct 954 is fixed to the upper plate straddling between the side plates, and a blower fan 951 is provided on the upper portion thereof. The connection duct 954 is connected to the blowing duct 952 so as to be able to guide the air sent out by the blower fan 951 into the blowing duct 952. Here, “communication is possible” means that an air flow path can be formed. As shown in the figure, the connecting duct 954 and the blowing duct 952 are formed out of phase, and the blowing duct 952 is connected via a communication portion 955 in which the air flow sent downward from the blower fan 951 flows in the horizontal direction. It is in the structure to enter.

  The communication portion 955 is a boundary between the connection duct 954 and the blowing duct 952, and the switching portion D is provided in the training portion 955 so as to be rotatable about the support shaft J as a fulcrum. The switching member D in the figure is in a horizontal position rotated 90 degrees from the initial position. That is, the switching member D is at a position where the connection duct 954 and the blowing duct 852 are communicated. The switching member D in the communication state is a position that closes a discharge portion of a blowing duct described later. In addition, it is not essential to close the discharge portion in the communication state, and an appropriate shape can be obtained depending on the specification. Further, the initial position of the switching member D is a position where the communication portion 955 between the connection duct 954 and the blowing duct 952 is closed.

  As a driving means of the switching member D, for example, a spring that biases the switching member D in the direction of the initial position, an eccentric cam that drives the switching member D in a communication state against the biasing force of the spring, and the like Can be achieved by known techniques. Further, the switching member D is positioned at the initial position by using its own weight, while the pulley and the motor are used to rotate the wire, one end of which is locked to the switching member D, to be in a communication state. You can also. Furthermore, the structure provided with the elastic member (not shown) which urges | biases the switching member D in the direction which maintains the blowing duct 952 and the connection duct 954 in a non-communication state may be taken. In this case, the switching member D can be rotated (turned) by the air flow (wind pressure) generated by driving the blower fan, so that the blowing duct 952 and the connection duct 954 can communicate with each other.

  Returning to the description, on the side opposite to the blowing portion 953 of the blowing duct 952, air staying in the vicinity of the blowing portion entering from the blowing portion 953 when the blower fan is not driven is a predetermined place in the apparatus. A discharge portion 956 for discharging is provided. In the first embodiment, a discharge duct 957 is provided in the discharge portion 956 so that the high-humidity air discharged does not touch the blower fan 951. The discharge duct 357 has a height position similar to the top position of the blower fan 951, but may be shorter in some cases. The discharge duct 957 is not an essential configuration. Further, the blowing duct 952 and the discharge duct 957 may be integrated.

  As described with reference to FIG. 1, the image forming apparatus is provided with an exhaust fan (see F in FIG. 1) for discharging the air in the apparatus to the outside of the apparatus. Therefore, for example, the positional relationship between the exhaust unit 956 and the exhaust fan F can be made so that the air exhausted from the exhaust unit 956 is exhausted to the outside due to the action of the exhaust fan F described above. desirable. In other words, unlike the illustrated configuration, the discharge portion side of the blowing duct may be angled or bent in relation to the operating range of the exhaust fan.

  Furthermore, you may comprise so that the end of the discharge duct 957 in the opposite side to the discharge part 956 side may contact | connect the exterior of an apparatus. In addition, one end of the above-described exhaust duct may be extended to a position close to the exhaust fan so that the operation of the exhaust fan described above can be surely received, and the degree of freedom in design is wide. These configurations are also applied to other embodiments described later.

  The operation of the air blowing device 95 having the above configuration will be briefly described. When the blower fan 951 is driven at a predetermined timing according to the image forming process, the surrounding air is sucked into the blower fan 951 and sent out to the connection duct 954. Next, the sent air flow is sent into the blowing duct 952 through the communication portion 955 that is in communication with the rotation of the switching member D, and is discharged from the blowing portion 953 formed in a narrow shape. . When the air blowing operation on the predetermined transfer material is finished, the blower fan 951 is not driven, and the switching member D returns to the initial position and switches the connection duct 954 and the blowing duct 952 to the non-communication state. A high humidity atmosphere (air) containing moisture released from the transfer material after the fixing process and staying in the vicinity of the blowing portion 953 enters the blowing portion 953 and rises in the blowing duct 951, eventually. It is discharged out of the apparatus by an exhaust fan F disposed in the image forming apparatus.

  In the configuration shown in the figure, when the discharge duct 957 is connected to the blowing duct 952, the high humidity atmosphere (air) staying in the vicinity of the blowing portion 953 that has entered from the blowing portion 953 is the difference between the two ducts. After the discharge portion 956 (position of the switching member D in the communication state as shown in FIG. 4) as a boundary is raised in the vertical direction, the discharge portion 956 is discharged outside the apparatus. That is, since there is no communication portion 955 at a position that hinders the path of the high humidity air to rise, the high humidity air is prevented from blowing through the duct 952 and reaching the blower fan 951.

  Further, as shown in FIG. 4 and FIGS. 5 and 6 described later, the communication portion 955 causes the air flow sent downward from the blower fan 951 to flow in the horizontal direction and blows the air flow into the duct 952. Yes. In other words, the communication portion 955 is not on the path where the high-humidity air that has entered from the blowing portion 953 rises in the blowing duct 952. That is, as shown in FIGS. 4 to 6, by providing the communication portion 955, the high humidity air is prevented from passing through the blowing duct 952 and reaching the blower fan 951. As a result, adhesion of water droplets to the blower fan 951 that is the blower means is suppressed and the problem of the blower fan of the blower fan can be more effectively prevented.

  A second embodiment relating to the air blowing device will be described with reference to FIG. The configuration of the air blowing device 95 shown in FIG. 5 is basically the same as the configuration shown in FIG. The difference is that the horizontal duct where the blowing duct 952 and the connecting duct 954 are connected is lengthened. In this case, the left side of the figure is the blowing duct 952 and the right side of the figure is the connection duct 954 with the communication portion 955 as a boundary. Further, the rotatable switching member D is arranged with the position of the communication portion 955 as the initial position as shown in the drawing as the initial position. This configuration can further reduce, for example, the risk of exposure of the blower fan 951 and electronic components to the high-humidity air discharged from the discharge portion 926 of the blowing duct 952.

  Next, a third embodiment of the air blowing device will be described with reference to FIG. In addition, since the structure of the air blowing apparatus in the frame of the side plate shown with a dashed-two dotted line has the same structure as FIG. 4, illustration is abbreviate | omitted. The difference from the configuration of FIG. 4 is that the switching member D is configured to be a slide type instead of a rotary type. The sliding type switching member D in the present embodiment can move in the vertical direction in a slit 958 formed at the boundary between the blowing duct 952 and the connection duct 954. For example, a linear solenoid is used as a drive source. . Then, the drive source is driven almost simultaneously with the drive of the blower fan 591 to raise the switching member, whereby the state of the connection duct 954 and the blowing duct 952 is switched from the non-communication state, which is the initial position, to the communication state.

  Further, the switching member D is returned to the initial position by driving the solenoid in response to the timing at which the blower fan 951 is switched to non-drive. As a result, the switching member D brings the connection duct 954 and the blowing duct 952 out of communication. The drive control for the drive source and the blower fan described above is performed via the control means S as described above.

  Next, a fourth embodiment of the air blowing device will be described with reference to FIG. The configuration in this embodiment has a configuration in which the positional relationship between the blower fan 591 and the blowing duct 952 in FIGS. 4 and 5 is reversed. The boundary between the connection duct 954 provided immediately below the blower fan 951 and the blowing duct 952 having a bent portion is the position of the communication portion 955 shown in the figure. In the communication portion 955, a switching member D that can rotate (turn) around the support shaft J is disposed. The switching member D maintains the connection duct 954 and the blowing duct 952 in a non-communication state at the initial position shown in the figure, and rotates 90 degrees during the driving of the blower fan 951 to connect the connection duct 954 and the blowing duct 952. Keep in communication. As a means for maintaining the switching member D at the initial position, for example, a spring can be used, and a driving source for rotating the switching member D for bringing the switching member D into a communicating state can be an air flow when the blower fan 951 is driven. . Or it can comprise suitably by application of the well-known technique mentioned above or its combination. In the fourth embodiment, a discharge duct 957 is provided as in the first embodiment.

  Further, the switching member D in the host machine configuration may be a slide type shown in FIG. 6 instead of the rotary type. For example, as shown in FIG. 8 showing the fifth embodiment, a slit 958 is provided in the connection duct 954 and the blowing duct 952, and a plate-like switching member D is inserted. When the switching member D is moved to one side, for example, the air passage of the blowing duct 952 is released simultaneously with closing the air passage of the connection duct 954, and is moved to the position where the air passage of the blowing duct 952 is closed. In such a case, the connection duct 952 may be configured to release the air path.

  The present invention is not limited to the above-described embodiment, but includes applications and modifications that do not depart from the scope of the claims.

  For example, in this embodiment, the connection duct 954 and the blowing duct 952 are handled as separate members, but the present invention is not limited to this, and the connection duct 954 and the blowing duct 952 are integrally configured. It may be.

  Further, the position of the discharge unit 956 is not limited to the present embodiment. That is, the discharge unit 956 may be located above the blowing unit 953 in the blowing duct 952 so that the air entering from the blowing unit 953 can be discharged to a predetermined place in the apparatus. Therefore, for example, in addition to the present embodiment, an opening such as a hole may be provided at the position of the blowing duct 852 satisfying the above position, and this opening may be used as the discharge unit 956.

  In addition, the discharge unit 956 enhances the effect of preventing problems caused by water droplets adhering to the blower fan 951 that is a blower. That is, even if there is a case where the air entering from the blowing part 953 cannot be prevented by only the switching member D, this air is discharged by the discharge part 956, so that the occurrence of the above-described problems can be prevented. .

DESCRIPTION OF SYMBOLS 1 Automatic document feeder 2 Image reading part 3 Image forming part 4 Belt unit 5 Paper feed part 9 Fixing apparatus 90 Fixing means 95 Air blowing apparatus 951 Blower fan (blower means)
952 Blowing duct 953 Blowing part 954 Connection duct 955 Communication part 956 Discharge part 957 Discharge duct 958 Slit D Switching member S Control means

Claims (8)

An image carrier;
A transfer member for transferring a toner image formed on the image carrier to a transfer material;
A fixing device that heat-treats the transferred transfer material while conveying it through a nip formed by a first fixing member and a second fixing member;
An air blowing device;
In an image forming apparatus having
The air blowing device is
Air blowing means;
A blowing duct having a blowing portion that blows an air flow generated by driving the blowing unit toward a transfer material that has passed through a nip portion of the fixing device;
A connection duct connected to the blowing duct so as to be able to communicate and guiding the air sent out by the blowing means into the blowing duct;
A switching member that switches between a communication state in which the blowing duct and the connection duct communicate with each other and a non-communication state in which the blowing duct and the connection duct do not communicate with each other;
With
The switching member takes the communication state when the air blowing means is driven, and takes the non-communication state when the air blowing means is not driven.
An image forming apparatus. The blowing duct has a discharge part that discharges air entering from the blowing part above the blowing part,
The image forming apparatus according to claim 1. The switching member takes the communication state when the air blowing means is driven, and closes the discharge portion.
The image forming apparatus according to claim 2. The connection duct and the blowing duct are arranged so that an air flow generated by driving the blowing means flows in a horizontal direction at a communication portion between the connection duct and the blowing duct.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. A discharge duct connected to the blowing duct so as to enter the blowing section of the blowing duct and guide the air discharged from the discharge section to the outside of the image forming apparatus;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The blowing duct and the discharge duct are arranged so that the air discharged from the discharge portion flows in a vertical direction at the boundary between the blowing duct and the discharge duct.
The image forming apparatus according to claim 5. A support member that rotatably supports the switching member;
An elastic member that urges the switching member in a direction to keep the blowing duct and the connection duct in the non-communication state,
The switching member is rotated by an air flow generated by driving the air blowing means, and takes the communication state.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. A drive member for driving the switching member;
Control means for driving and controlling the drive member,
The control means controls the drive member based on the operating state of the blower means;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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