JP2007219076A - Image forming machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which prevents condensation and also prevents the fall of water drops onto paper, by efficiently removing the steam produced at the time of fixing an unfixed toner image to the recording medium, regarding the image forming apparatus forming the image consisting of a fixed toner image on the recording medium by forming an electrostatic latent image and developing the image with a toner to form the toner image, and by transferring and fixing the toner image in the final onto the prescribed recording medium. <P>SOLUTION: An adsorption belt 160 which is stretched to a driven roller 170 using a paper ejection roller 140 as a driving source and is moved cyclically clockwise in an arrow direction A is disposed between an aperture 10a and a fixing unit 130. The adsorption belt 160 also moves cyclically along a path passing through the upper side of the conveyance path where the paper fixed with the toner image by the fixing unit 130 is conveyed, and the vicinity of the aperture 10a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention forms an electrostatic latent image, develops it with toner, forms a toner image, and finally transfers and fixes the toner image onto a predetermined recording medium, thereby forming a fixed toner image on the recording medium. The present invention relates to an image forming apparatus for forming an image.

  In an image forming apparatus used for an electrophotographic copying machine, printer, facsimile, or the like, an image carrier represented by a photosensitive drum or the like is uniformly charged, and exposure light carrying image information is supplied to the image carrier. To form an electrostatic latent image on the image carrier, develop the electrostatic latent image to form a toner image on the image carrier, and directly or directly form the formed toner image. For example, an intermediate transfer member is interposed and finally transferred onto a sheet and fixed, whereby an image composed of a fixed toner image is formed on the recording medium.

  In such an image forming apparatus, a sheet on which a toner image is transferred and an unfixed toner image is formed is passed through a nip portion formed by press-contacting a pair of fixing members each having a heat source therein. 2. Description of the Related Art A fixing device is widely used that melts a received toner image by heating and pressurizing and fixing the molten toner image on a sheet to form an image composed of a fixed toner image on the sheet.

  When the paper on which the unfixed toner image is formed passes through the nip portion, the water contained in the paper is heated by the heat source of the fixing device to generate water vapor. When it is continuously cooled, condensation occurs on the inner wall of the casing. When the condensed water generated in this way falls on the paper, there is a problem that the paper is contaminated and the image quality is deteriorated.

  As a means for coping with such a problem, a fan is disposed above the fixing device, and both heat generated from the fixing device and water vapor generated from the paper heated by the fixing device are forcibly discharged out of the image forming apparatus. Means are known. However, according to such means, a new problem such as noise caused by the fan occurs.

  Therefore, as a means for coping with both of these problems, an air path for discharging the heat generated from the fixing device and the water vapor generated when fixing the unfixed toner image onto the paper to the outside of the image forming apparatus is provided above the fixing device. The inner wall of the air passage is formed with a grid-like rib that prevents water droplets from falling due to water vapor condensation due to surface tension, and if necessary, a lattice-like rib is provided at the lowermost portion of the inner wall of the air passage. Means have been proposed for forming a reservoir of condensed water overflowing from (see, for example, Patent Document 1).

  According to the means proposed in Patent Document 1, heat and water vapor are discharged to the outside of the image forming apparatus through an air passage formed above the fixing device, and even if condensation occurs on the inner wall of the air passage, By holding the dew condensation water by the surface tension of the provided grid-like ribs, it is possible to prevent water droplets from falling on the paper. Further, by providing a reservoir at the lowermost part of the inner wall of the air passage, the dew condensation water overflowing from the grid-like ribs is stored.

  In addition, a means has been proposed in which a belt-like moisture absorbing member is disposed in a rotatable and replaceable state above the sheet conveyance path at the rear stage of the fixing device (see, for example, Patent Document 2).

  According to the means proposed in Patent Document 2, water vapor generated when fixing an unfixed toner image on a sheet is absorbed by the moisture absorbing member, so that the water droplets are prevented from falling on the sheet. Further, since the moisture absorbing member has a rotatable belt shape, the water absorption rate is higher than that of the configuration in which the moisture absorbing member is pasted above the sheet conveyance path at the subsequent stage of the fixing device. Moreover, when the water absorption of the water absorbing member deteriorates, the water absorbing function can be maintained by replacing the water absorbing member.

  Furthermore, a means has also been proposed in which a water droplet collecting member having a concentrating portion for concentrating water droplets generated by condensation is disposed above the fixing device, and water droplets collected by the water droplet collecting member are stored in a storage portion (for example, a patent Reference 3).

According to the means proposed in Patent Document 3, even if condensation occurs above the fixing device, the water droplets generated by the condensation are concentrated on the concentration portion of the water droplet concentration member, and are concentrated on the concentration portion. The water droplets dropped will fall into the storage part. Accordingly, water droplets are prevented from dropping on the paper. Further, by disposing the concentrated portion at a position where there is no problem in image formation, even if the water droplet falls without being concentrated on the concentrated portion, the water droplet is prevented from falling on the paper. Further, by disposing the storage section above, for example, the heat roller of the fixing device, water drops that have fallen on the storage section are evaporated by the heat of the heat roller, and water overflows from the storage section to contaminate the paper or image. Degrading is avoided.
JP-A-9-90855 JP-A-6-35360 JP-A-6-27844

  In the means proposed in Patent Document 1, it is necessary to secure a space for forming an air passage and a storage part in the image formation, and there are restrictions in designing the image forming apparatus.

  Moreover, in the means proposed in the above-mentioned patent document 2, since the replacement of the moisture absorbing member relies on human means, there may be a situation where the replacement time is delayed. If the replacement time of the moisture absorbing member is delayed, the moisture absorbed by the moisture absorbing member may overflow and water droplets may fall on the paper.

  Further, in the means proposed in Patent Document 3, by disposing the storage part above, for example, a heat roller of the fixing device, water drops falling on the storage part are evaporated by the heat of the heat roller, and the storage part Although it is possible to prevent the water from overflowing from the water, it takes a certain amount of heat energy to evaporate the water stored in the reservoir, so in order to secure the temperature required for fixing in the fixing device, The temperature must be raised.

  In view of the above circumstances, the present invention provides an image forming apparatus that efficiently removes water vapor generated at the time of fixing an unfixed toner image on a recording medium to prevent dew condensation and prevent water droplets from falling on a sheet. It is the purpose.

The image forming apparatus of the present invention that achieves the above object provides:
An electrostatic latent image is formed and developed with toner to form a toner image, and this toner image is finally transferred and fixed on a predetermined recording medium to form an image composed of a fixed toner image on the recording medium. In the image forming apparatus to
A housing in which an opening is formed;
A fixing device disposed in the casing and fixing the toner image on the recording medium by heating the recording medium on which the toner image is transferred;
In the casing, disposed between the opening formed in the casing and the fixing device, and above the conveyance path through which the recording medium on which the toner image is fixed by the fixing device is conveyed and in the vicinity of the fixing device And an adsorbing belt that adsorbs water vapor generated when the toner image is fixed by the fixing device by circulating and moving in a predetermined direction along a route passing therethrough and the vicinity of the opening.

  In the image forming apparatus according to the present invention, the suction belt provided between the opening and the fixing device is disposed above the conveying path on which the recording medium on which the toner image is fixed by the fixing device is conveyed. It circulates in a predetermined direction along a route passing through the vicinity and the vicinity of the opening. According to the image forming apparatus of the present invention, the water vapor generated at the time of fixing the toner image by the fixing unit is generated when the suction belt passes above the conveyance path along which the recording medium on which the toner image is fixed by the fixing unit is conveyed. The water adsorbed and adsorbed by the adsorbing belt is evaporated by the heat of the fixing device when the adsorbing belt passes through the vicinity of the fixing device, and the evaporated water vapor is discharged from the housing as needed through the opening. Further, according to the image forming apparatus of the present invention, the adsorption belt is cooled by passing through the vicinity of the opening, so that the adsorption ability of water vapor by the adsorption belt is maintained. In this way, water vapor generated during the fixing of the unfixed toner image onto the recording medium is efficiently removed. Therefore, even if the image forming apparatus of the present invention is operated for a long time, the housing is not replaced. Condensation is prevented from occurring on the body wall, and water droplets are prevented from falling on the paper.

  Further, since the image forming apparatus of the present invention does not require a fan for discharging water vapor, an increase in noise is avoided. Further, since the suction belt of the image forming apparatus of the present invention can be disposed in a space-saving manner, the degree of freedom in designing the image forming apparatus is high. In addition, since the image forming apparatus of the present invention is configured to evaporate and discharge the moisture adsorbed on the adsorption belt as needed, the heat energy for evaporating the moisture is provided by the exhaust heat of the fixing device, and the heat source of the fixing device. There is no need to raise the temperature.

  In the image forming apparatus of the present invention, it is more preferable that the suction belt circulates in a direction in which the suction belt moves to the vicinity of the fixing device after adsorbing the water vapor.

  According to such a preferred embodiment, the moisture adsorbed on the adsorption belt is evaporated immediately by the heat of the fixing device immediately after being adsorbed, and is discharged from the opening.

  In the image forming apparatus of the present invention, it is also preferable that the suction belt has an uneven surface.

  According to such a preferable form, since the surface area of the adsorption belt is increased, the adsorption capability of the adsorption belt is increased and more water vapor can be adsorbed.

  Furthermore, in the image forming apparatus of the present invention, it is also preferable that the adsorption belt has a surface made of a water absorbing member.

  Even with such a preferable form, the adsorption belt can adsorb more water vapor.

  According to the present invention, there is provided an image forming apparatus in which water vapor generated at the time of fixing an unfixed toner image on a recording medium is efficiently removed to prevent dew condensation and to prevent water droplets from falling on a sheet.

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

  FIG. 1 is a schematic configuration diagram of an image forming apparatus 1 to which an embodiment of the image forming apparatus of the present invention is applied. Here, first, the positioning of the present invention will be described with reference to FIG.

  In the image forming apparatus 1 shown in FIG. 1, a photosensitive drum 110 is provided in a housing 10, and for example, a paper cassette 20 in which a standard size paper represented by B5 size paper or A4 size paper is accommodated. 4 are installed. The housing 10 corresponds to an example of the housing according to the present invention.

  The photosensitive drum 110 shown in FIG. 1 has a drum shape rotating in a predetermined direction, and FIG. 1 also shows a transfer roller 120 provided so as to be in contact with the surface of the photosensitive drum 110. In the image forming apparatus 1 shown in FIG. 1, the area where the photosensitive drum 110 and the transfer roller 120 are in contact is the transfer area. The paper stored in the paper cassette 20 is conveyed toward the transfer region by various rollers (not shown).

  A charging device, an exposure device, a developing device, and the like are provided around the photosensitive drum 110 shown in FIG. 1, but are not shown here. The surface of the drum-shaped photoconductor drum 110 is uniformly charged by a charger, and then exposure light carrying image information is exposed by an exposure device to form an electrostatic latent image on the surface of the photoconductor drum 110. Is done. The electrostatic latent image formed on the surface of the photosensitive drum 110 is developed by a developing device to become a toner image. This toner image is transferred onto a sheet fed from the sheet cassette 20 and sent to the transfer area. In addition, the image forming apparatus 1 shown in FIG. 1 is also provided with a fixing device 130 for fixing the toner image on the sheet by heating the sheet on which the toner image is transferred and the unfixed toner image is formed. The sheet on which the toner image has been transferred in the transfer area is sent to the fixing device 130, where the toner image is fixed on the sheet, and an image composed of the fixed toner image is formed on the sheet. The fixing device 130 corresponds to an example of a fixing device according to the present invention.

  In addition, the image forming apparatus 1 shown in FIG. 1 includes a stacking tray 30 on which sheets after image formation is stacked, and a pair of discharges that discharge the conveyed sheets toward the stacking tray 30. A roller 140 is provided. The sheet on which the image composed of the fixing toner image is formed is further conveyed by various rollers, sent to the sheet discharge roller 140, discharged to the stacking tray 30, and stacked on the stacking tray 30.

  Here, the image forming apparatus 1 shown in FIG. 1 is characterized by the fixing device 130 provided in the image forming apparatus 1 and the elements provided around the fixing device 130 as an embodiment of the present invention. In the following, the fixing device 130 and elements provided around the fixing device 130 will be described in detail.

  FIG. 2 is an enlarged view of the fixing device 130 shown in FIG. 1 and elements provided around the fixing device 130.

  FIG. 2 shows the fixing device 130 and the paper discharge roller 140 also shown in FIG.

  As shown in an enlarged view in FIG. 2, above the fixing unit 130, a plastic having a comb-teeth shape for transporting the paper on which the toner image has been fixed in the fixing unit 130 toward the paper discharge roller 140. A paper guide 150 made of paper is provided.

  Further, as shown in an enlarged view in FIG. 2, an opening 10 a is formed in the housing 10. The opening 10a corresponds to an example of the opening according to the present invention.

  Further, as shown in an enlarged view in FIG. 2, between the opening 10 a and the fixing device 130, it is stretched around a driven roller 170 having a paper discharge roller 140 as a drive source, and circulates in a clockwise arrow A direction. A suction belt 160 is provided. The suction belt 160 circulates and moves along a path passing through the conveyance path through which the sheet on which the toner image is fixed by the fixing device 130 is conveyed, the vicinity of the fixing device 130, and the vicinity of the opening 10a. It is. The suction belt 160 corresponds to an example of the suction belt referred to in the present invention.

  When the paper on which the unfixed toner image is formed passes through the fixing device 130, the water contained in the paper is heated by the heat source of the fixing device 130 to generate water vapor. The water vapor generated in this way is adsorbed when the adsorbing belt 160 passes above the conveyance path through which the paper on which the toner image is fixed by the fixing device 130 is conveyed.

  The adsorption belt 160 circulates in the direction in which the adsorption belt 160 moves to the vicinity of the fixing device 130 after adsorbing the water vapor, and moisture adsorbed on the adsorption belt 160 is fixed by the adsorption belt 160. The vapor evaporated by the heat of the fixing unit 130 when passing through the vicinity of the unit 130, and the evaporated water vapor is discharged to the outside of the housing 10 as needed through the opening 10 a.

  Further, the adsorption belt 160 is cooled by passing through the vicinity of the opening 10a, so that the adsorption ability of water vapor by the adsorption belt is maintained.

  As described above, the paper guide 150 is disposed above the fixing device 130. Since the paper guide 150 is made of plastic, the paper guide 150 is heated by the heat of the fixing device 130. Condensation does not occur in the guide 150.

  As described above, according to the image forming apparatus 1 of the present embodiment, the water vapor generated at the time of fixing the unfixed toner image onto the paper is efficiently removed. Therefore, the image forming apparatus 1 is operated for a long time. However, without replacing the suction belt 160, it is possible to prevent dew condensation from occurring on the inner wall of the housing 10, and to prevent water droplets from falling onto the paper. Therefore, the contamination of the paper and the deterioration of the image quality due to the condensation water falling on the paper are prevented.

  Further, since the image forming apparatus 1 of the present embodiment does not require a fan for discharging water vapor, an increase in noise is avoided. Further, since the suction belt 160 of the image forming apparatus 1 of the present embodiment can be disposed in a space-saving manner, the degree of freedom in designing the image forming apparatus 1 is high. In addition, since the image forming apparatus 1 of the present embodiment is configured to evaporate and discharge the moisture adsorbed on the adsorption belt 160 as needed, the heat energy for evaporating the moisture can be provided by the exhaust heat of the fixing device 130 and the fixing. There is no need to increase the temperature of the heat source of the vessel 130.

  FIG. 3 is an enlarged view of the suction belt 160 shown in FIG.

  As shown in FIG. 3, the suction belt 160 has irregularities 160 a having a trapezoidal cross section on the surface. Further, the surface of the adsorption belt 160 is made of a water absorbing member such as a highly water absorbing polymer or a water absorbing polymer gel.

  By using such an adsorption belt 160, the surface area of the adsorption belt 160 increases, the adsorption capability of the adsorption belt 160 increases, and more water vapor can be adsorbed.

  FIG. 4 is an enlarged view of the suction belt 161 according to another embodiment.

  The suction belt 161 shown in FIG. 4 has unevenness 161a having a semicircular cross section on the surface.

  The uneven shape formed on the surface of the suction belt may be an uneven surface 160a having a trapezoidal cross section as shown in FIG. 3, or an uneven surface 161a having a semicircular cross section as shown in FIG. The shape is not limited. Further, as described above, the adsorption belt preferably has irregularities formed on the surface, but the adsorption belt referred to in the present invention may have no irregularities formed on the surface.

  In the above-described embodiment, the example in which the adsorption belt according to the present invention has a surface made of a water-absorbing member has been described. However, the adsorption belt according to the present invention is not limited to this, and the non-water absorption It may consist of members. In this case, the water vapor generated at the time of fixing becomes dew condensation due to a temperature difference between the adsorption belt and the water vapor and adheres to the adsorption belt. Further, since the water vapor generated from one sheet is insignificant, it does not fall onto the sheet.

1 is a schematic configuration diagram of an image forming apparatus to which an embodiment of an image forming apparatus of the present invention is applied. FIG. 2 is an enlarged view of the fixing device shown in FIG. 1 and elements provided around the fixing device. FIG. 3 is an enlarged view of the suction belt shown in FIG. 2. It is an enlarged view of the adsorption belt of other embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Case 10a Opening 110 Photosensitive drum 120 Transfer roller 130 Fixing device 140 Paper discharge roller 150 Paper guide 160,161 Adsorption belt 160a, 161a Concavity and convexity 170 Drive roller 20 Paper cassette 30 Loading tray

Claims (4)

An electrostatic latent image is formed, developed with toner to form a toner image, and the toner image is finally transferred and fixed on a predetermined recording medium to form an image composed of a fixed toner image on the recording medium. In the image forming apparatus to
A housing in which an opening is formed;
A fixing device disposed in the casing and fixing the toner image on the recording medium by heating the recording medium on which the toner image is transferred;
In the casing, disposed between the opening formed in the casing and the fixing unit, and above the conveyance path through which the recording medium on which the toner image is fixed by the fixing unit is conveyed, and in the vicinity of the fixing unit And an adsorbing belt that adsorbs water vapor generated when the toner image is fixed by the fixing device by circulating and moving in a predetermined direction along a path that passes through and the vicinity of the opening. Forming equipment.   The image forming apparatus according to claim 1, wherein the suction belt circulates in a direction in which the suction belt moves to the vicinity of the fixing device after adsorbing the water vapor.   The image forming apparatus according to claim 1, wherein the suction belt has an uneven surface.   The image forming apparatus according to claim 1, wherein a surface of the suction belt is made of a water absorbing member.

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