JPH08202179A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] An image forming apparatus configured to guide a transfer material carrying an unfixed toner image from a predetermined angle along a top surface of a guide plate against a roller pair including a fixing roller and a pressure roller. It is an object of the present invention to provide a configuration in which the transfer material is prevented from rising from the guide plate and the transfer material can always be guided from a predetermined angle with a minimum number of additional devices. [Structure] One or a plurality of through holes 60 are formed in a guide plate 50, and the lower surface of the guide plate 50 is made to communicate with the exhaust device 53 formed on the outer wall 52 of the device body 1 through the ducts 51 and 13, and the exhaust device 53 The inside of the apparatus is exhausted, and the transfer material is guided while being attracted to the upper surface of the guide plate 50 through the through hole 60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine and a printer, and more particularly, to a roller pair consisting of a fixing roller and a pressure roller, a transfer material carrying an unfixed toner image on a guide plate. The present invention relates to an image forming apparatus capable of guiding a transfer material along a top surface without lifting and always guiding a transfer material to a roller pair from a predetermined angle.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus, a desired toner image is formed on an image bearing member such as a photosensitive drum, and this toner image is transferred onto an appropriate transfer material such as paper by the action of a transfer corona discharger or the like. It is configured to let. In such a structure, the transfer material on which the toner image has been transferred is separated from the image carrier at a predetermined separation position by a separating device such as a separating corona discharger, and then sent to a fixing device by a carrying device such as a carrying belt, and the like. It is heated and fixed. During the period from such separation to fixing, there are some problems with the transfer material transfer.

One of them is the angle of incidence of the transfer material on the roller pair consisting of the fixing roller and the pressure roller. If the angle is not proper, defects such as wrinkles will occur on the transfer material during fixing. . One of the other problems is delay of the separation position of the transfer material from the image carrier. When such a delay occurs, the tip side of the transfer material is elastically bounced or the toner once transferred to the transfer material. Occurs again on the side of the photosensitive drum, causing a transfer image defect such as blurring or bleeding of the transfer toner image.

With respect to the generation of wrinkles associated with the incident angle of the transfer material, a guide plate whose tilt angle can be adjusted is provided in front of the fixing roller pair, and the guide plate is adjusted to an appropriate tilt angle before being guided. This is dealt with by guiding the transfer material along the upper surface of the plate. Regarding the latter transfer image failure, some peeling claws can be placed in contact with the image carrier to prepare for the case where the separation corona discharger alone does not separate at a predetermined position. We are trying to separate the transfer material within the proper position as much as possible.

[0005]

However, even with the above-mentioned configuration, in an image forming apparatus that handles a large-sized transfer material such as A0 to A2 sizes, the size and thickness of the transfer material, Or, due to the weakness of the "strain" that accompanies them, the transfer material itself floats up from the guide surface of the guide plate at a partial portion, even though the inclination angle of the guide plate guiding the fixing roller pair is properly adjusted. In some cases, it is not possible to obtain the expected predetermined incident angle, and in such a case, the wrinkles of the transfer material appear as described above. Similarly, the separation position of the transfer material from the image carrier tends to be delayed, which may cause an undesirable phenomenon such as blurring, bleeding or loss of the transferred image, and further damage to the photoconductor by the separation claw. There is also such a problem.

The present invention has been made in view of the above circumstances, and the first problem to be solved is to guide the transfer material to the fixing roller pair without rising, and to always transfer the transfer material along the guide plate at a predetermined position. It is an object of the present invention to provide a structure capable of being incident from the above angle, and particularly to provide such a structure in a simple form as much as possible without requiring an additional device.

Another object of the present invention is to provide a structure in which the separation of the transfer material from the image carrier is stabilized by using a part of the structure related to the guide to the fixing roller pair in common. is there.

Still another object of the present invention is to provide a simple structure in which a part of the structure relating to the guide to the fixing roller pair and the separation of the transfer material is shared with the means for exhausting the inside of the apparatus main body. Especially.

[0009]

In order to solve the above-mentioned problems, the present invention provides a roller pair consisting of a fixing roller and a pressure roller with a transfer material carrying an unfixed toner image along the upper surface of a guide plate. In an image forming apparatus configured to guide from a predetermined angle, one or a plurality of through holes are formed in the guide plate, and a lower surface of the guide plate is connected to an exhaust device formed on an outer wall of the apparatus main body through a duct. The inside of the device is exhausted by an exhaust device, and the transfer material is guided while being drawn to the upper surface of the guide plate through the through hole.

In particular, the through holes are a plurality of holes formed on the guide surface of the guide plate, or are elongated gaps formed on the front edge of the guide plate.

Further, according to the present invention, a transfer means for transferring the transfer material separated from the image carrier to a fixing device composed of a fixing roller and a pressure roller, and a transfer material from the transfer means to the fixing device. In an image forming apparatus having a guide plate for guiding, a suction port for attracting the transfer material separated from the image carrier and guiding it to the carrier is provided between the image carrier and the carrier. The guide plate is provided with through holes for attracting the transfer material conveyed on the upper surface to the upper surface, and these intake ports and through holes are communicated with a common exhaust device arranged on the outer wall of the apparatus main body through a common duct. In a preferred embodiment, such an exhaust device is provided above a transfer material tray for receiving the transfer material discharged outside the apparatus main body, and exhaust air from the exhaust device is transferred onto the transfer material tray. And wherein the thing is blown towards.

[0012]

In this structure, the transfer material guided by the pair of fixing rollers is bent or floated while being attracted to the upper surface of the guide plate which is adjusted to a predetermined angle by the intake air from the through hole formed in the guide plate. Without being guided, it is always stably fed to the fixing roller pair from a predetermined angle. This intake can be commonly performed by an exhaust device for exhausting the inside of the apparatus main body. Further, by sharing a part of these configurations, the configuration is such that air is sucked from the suction port between the image carrier and the transporting means. It acts so as to separate the transfer material from the image carrier at a predetermined separation position without any defect in the transferred image.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an example of an image forming apparatus according to the present invention. An image forming section 2 for forming a toner image and a fixing device 3 for fixing the toner image on a transfer material are provided on an upper part of an apparatus main body 1. The roll paper feeding unit 4 is arranged in one of the space-saving, substantially triangular spaces below the apparatus body 1, and the other space 6 is provided with a transfer material for accumulating the transfer material. The tray 7 is arranged.
In the illustrated example, the paper feed unit 4 has two roll papers of different sizes loaded therein, one of the roll papers selected based on the paper feed signal is unwound, and then the paper is cut into the selected size and then the image is formed. It is conveyed to the transfer section of the forming section 2. Further, the transfer material after the transfer is discharged to the outside of the machine by a discharge roller 5 through a conveying means and a fixing device which will be described later, and is sequentially stacked on the transfer material tray 7.

The image forming section and the apparatus will be briefly described. The image forming section 2 has, for example, a photosensitive drum 21 having a photosensitive member on the surface as an image bearing member, and the surface of the photosensitive drum 21 around the photosensitive drum 21. To a specific polarity, a corona charger 22, an image exposure device 23 that projects an optical image of an original to form an electrostatic latent image on the surface of the photosensitive drum 21, and develops this latent image to form a toner image. Developing device 24, a transfer corona discharger 25 for transferring a toner image to the transfer material fed from the paper feed section 4, and an AC discharge from the back surface of the transfer material to remove the charge and separate the transfer material from the photosensitive drum 21. Separate corona discharger 26, a cleaning device 27 for removing the developer remaining on the surface of the photosensitive drum 21 after transfer, and an eraser for uniformly removing the surface potential of the photosensitive drum 21 after cleaning. Have in place the lamp 28. These devices sequentially operate as the photosensitive drum 21 rotates in the arrow direction. The fixing device 3 is a pair of rollers arranged in pressure contact with each other, that is, the fixing roller 3 having a heat source inside.
1 and a fixing roller pair consisting of an elastic pressure roller 32 that is in pressure contact with the fixing roller 1. Although not shown in the drawing, a temperature detecting sensor for controlling the fixing temperature, a coating means for coating the fixing roller with an offset preventing liquid, a well-known means such as a peeling claw are arranged around the fixing roller. ing.

A document feeder 8 is arranged at the top of the apparatus. When a document is inserted from the document insertion port 81 of the apparatus 8 toward the right side in the drawing, the document is fed along the passage thereof. Is conveyed in synchronization with the rotation of the photosensitive drum 21, and at that time, each of the above-mentioned devices operates as described above to form a toner image according to the original image on the transfer material.

A conveying belt 9 is provided as a conveying means for conveying the transfer material separated from the photosensitive drum 21 to the fixing device 3. Further, an intake port 11 is provided between the photosensitive drum 21 and the conveying belt 9. Has been formed. The suction port 11 communicates with a later-described common duct 13 through the duct 12, and sucks the transfer material separated by the action of the separation corona device 26 to assist in separating the transfer material at a predetermined timing.

The conveyor belt 9 is made up of one or a plurality of belt-shaped endless belts, and the support rollers 1 are arranged apart from each other.
The photosensitive drum 2 is stretched around the photosensitive drums 2 and 15 by rotating one of the supporting rollers by a driving source (not shown).
The transfer material moves in a clockwise direction in synchronization with the transfer speed of 1, and the transfer material is placed on the upper surface and transferred. In the embodiment, the suction fan 16 is provided inside the loop of the conveyor belt 9 so that the transfer material is sucked toward the belt side through the through hole provided in the belt or the through hole provided between the belts. It is transported without floating. The suction fan 16 is exhausted to the outside of the machine through a duct (not shown) on the side of the device.

The transfer material conveyed by the conveyor belt 9 is guided toward the nip between the fixing roller 31 and the pressure roller 32 by the guide plate 50 having a smooth guide surface (upper surface). The guide plate extends along the entire width direction of the fixing roller 31 and the pressure roller 32, and its front edge is positioned at the entrance of the nip between the fixing roller 31 and the pressure roller 32 or slightly above or below the entrance. It is arranged to. As mentioned above, the angle of incidence of the transfer material on these roller pairs can cause wrinkling of the transfer material if it is incorrect. For this reason, the guide plate 50 has an appropriate tilt angle adjusting mechanism so as to change the tilt angle of the guide surface that determines the incident angle, that is, the upper surface. As such an inclination angle adjusting mechanism, for example, the configuration proposed in Japanese Patent Application No. 5-130962 by the present applicant can be used.

Along the upper surface of the properly adjusted guide plate 50, one or a plurality of through holes 60 are formed in the guide plate 50 in order to guide the transfer material without floating, and the through holes 60 are provided downward. The transfer material is attracted to the upper surface of the guide plate 50 by suction.

FIG. 2 shows an example of such a through hole 60. A plurality of through holes 60 are formed on the upper surface of the guide plate 50 in the entire width direction or a part thereof. Such through holes may be regularly arranged or random.
Further, FIG. 3 is formed in the shape of an elongated gap formed along the width direction at the front edge of the guide plate 9, that is, the edge toward the fixing roller 31.

In any of these structures, the lower surface of the guide plate 60 is formed by the duct 51 and the common duct 1 described above.
3 is communicated. In the illustrated example, the common duct 13 is communicated with an exhaust device 53 such as a suction fan arranged on the outer wall of the device body provided for exhausting the inside of the device body, and is inhaled thereby. Guide plate 6 as shown
0 and the gap 90 formed at the upper end of the duct 13 are provided to allow adjustment of the inclination angle of the guide plate 50.
In addition to the gap, flexible or bellows may be used for connection, but by forming such a gap, air in the device can be ventilated from the gap.

The exhaust device 53 is directed to the upper surface of the transfer material tray 7, is provided so as to blow the air discharged outside the apparatus toward the upper surface of the transfer material, and an appropriate number of units are provided in the direction perpendicular to the paper surface. It is provided and also has a function of discharging ozone generated from a corona discharger or the like inside the apparatus and hot air generated from the fixing device 3 through the filter, and minimizes a factor that adversely affects image formation.

On the other hand, the transfer material fixed as described above is discharged to the outside of the apparatus main body 1 by the discharge roller 5 and contacts the transfer material tray 7 and is accumulated while sliding. Since a large-sized transfer material is apt to be bent or wavy when the tray is stored, there is a case where the transfer material in the next order is caught by the transfer material and the smooth transfer cannot be performed. On the other hand, according to the present invention, since the air blown from the exhaust device 53 is blown toward the upper surface of the transfer material as described above, floating of the accumulated transfer material is prevented, and the next transfer material is prevented. Are smoothly collected without being caught.

[0024]

According to the image forming apparatus of the present invention, the transfer material can be brought into close contact with the guide surface of the guide plate by the suction from the lower side of the guide plate to guide the transfer material in a state where the transfer material is not lifted up. It is possible to minimize the occurrence of wrinkles during fixing by making the light incident on the fixing roller pair from a predetermined angle.

Further, by using the suction means together for separating the photosensitive member 21, it is possible to provide a simple structure in which additional devices are minimized.

Furthermore, heat, ozone, etc. generated in the device by the common exhaust device can be effectively removed by being sucked by the second suction means, and a large size can be obtained by the blown air. The transfer material can also be collected in an orderly manner.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an example of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing an example of a through hole of a guide plate of the fixing device of the image forming apparatus according to the present invention.

FIG. 3 is a diagram showing another example of the through holes of the guide plate of the fixing device of the image forming apparatus according to the present invention.

[Explanation of symbols]

 1 Device Main Body 3 Fixing Device 7 Transfer Material Tray 8 Conveying Device 9 Conveying Belt 11 Suction Port 21 Image Carrier 26 Separating Corona Discharger 31 Fixing Roller 32 Pressure Roller 50 Guide Plate 60 Through Hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Egashira 4-21-3 Shimomaruko, Ota-ku, Tokyo Katsurakawa Electric Co., Ltd.

Claims (5)

[Claims] 1. An image forming apparatus in which a transfer material carrying an unfixed toner image is guided from a predetermined angle along a top surface of a guide plate with respect to a roller pair consisting of a fixing roller and a pressure roller. One or a plurality of through holes are formed in the plate, and the lower surface of the guide plate is connected to an exhaust device formed on the outer wall of the main body of the device through a duct, and the exhaust device exhausts the inside of the device. An image forming apparatus characterized in that the transfer material is guided while being attracted to the upper surface of a guide plate via the transfer material. 2. The image forming apparatus according to claim 1, wherein the through holes are a plurality of holes formed on the guide surface of the guide plate. 3. The image forming apparatus according to claim 1, wherein the through hole is an elongated gap formed at the front edge of the guide plate. 4. A transport means for transporting the transfer material separated from the image carrier to a fixing device comprising a fixing roller and a pressure roller, and a guide plate for guiding the transfer material from the transport means to the fixing device. In the image forming apparatus, a suction port for attracting the transfer material separated from the image carrier and guiding it to the transport unit is provided between the image carrier and the transport unit, and the upper surface of the guide plate is transported to the guide plate. Through hole for attracting the transfer material to the upper surface, and the intake port and the through hole are connected to a common exhaust device arranged on the outer wall of the apparatus main body through a common duct. . 5. The exhaust device is provided above a transfer material tray for receiving the transfer material discharged outside the apparatus main body, and exhaust air from the exhaust device is blown toward the transfer material on the transfer material tray. The image forming apparatus according to claim 4, wherein