JPH0536458U - Recording paper guide structure for image forming apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] The recording paper on which the unfixed toner image transferred from the photosensitive drum adheres to the lower surface is guided smoothly from the transfer unit to the fixing device without disturbing the toner image and is smoothly introduced into the fixing device. The recording paper guide structure of the image forming apparatus that enables the face-down paper discharge with a simple structure. [Structure] Between a transfer portion in which a transfer charger 66 is arranged above a photosensitive drum 61 and a fixing device 67 in which a heat roller 67A and a press roller 67B are arranged in pressure contact with each other, a recording paper conveyance path regulation plate 21F is provided in the fixing device 67. And the tangent line S1 at the end T on the side adjacent to
The recording paper having the most rigidity used by the image forming apparatus, which passes between the rotation centers CA and CB of A and 67B and which has the end: T on the surface of the photosensitive drum 61 of the transfer portion and adjacent to the fixing device 67. Curve of natural curvature of: that curve connected by K: K
The tangent line: S2 at the end T on the side adjacent to the fixing device 67 is formed and arranged so as to pass between the rotation centers CA and CB of both rollers 67A and 67B of the fixing device 67.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure of a recording paper guide member for guiding a recording paper in an image forming apparatus that prints or draws output information of a computer or the like on the recording paper conveyed from a paper feeding unit.

[0002]

[Prior Art]

 Image forming apparatuses (so-called printers) that print or draw output information from a computer, word processor, facsimile, or the like on recording paper to obtain a hard copy include various types of image forming methods and recording papers used. In recent years, there has been a marked increase in the number of products that use electrophotography to form images on cut paper that has been cut into a predetermined size in advance. In electrophotography, the photoconductive material (photoreceptor) on the surface of the photosensitive drum is uniformly charged and then exposed to form a latent image with a missing charge, and toner is attached to the latent image for development. (Toner image formation), the toner image is transferred to recording paper, and the toner image is fixed on the recording paper by a fixing device.

By the way, when images are formed on continuous pages, face-down paper ejection, that is, by ejecting the surface on the image forming side downward and sequentially stacking on the back surface side, the page order is maintained as it is. Therefore, it is particularly preferable for a printer that prints a document. In the case of an image forming apparatus using the electrophotographic method, the upper side of the photosensitive drum is used as a transfer unit, a recording paper conveyance path is formed on the upper side of the photosensitive drum, and the toner is formed on the lower surface of the recording paper conveyed through the recording paper conveyance path. By transferring the image and fixing it as it is (a state in which the toner image is adhered to the lower surface) and discharging the sheet, the face down sheet can be discharged as described above.

[0004]

[Problems to be solved by the device]

 However, as described above, in the image forming apparatus using the electrophotographic method, when the image is formed on the lower surface of the recording paper conveyed through the recording paper conveyance path above the photosensitive drum, It is necessary to convey the recording paper on which the unfixed toner image is attached to the lower surface from the transfer section to the fixing device without disturbing the toner image, and it is difficult to hold and guide it, and it is difficult to introduce it well into the fixing device. It was a thing. It should be noted that the lower side of the photosensitive drum is used as the transfer section, the toner image is transferred onto the upper surface of the recording paper, and the recording paper is fixed in that state, and then the recording paper is reversed, so that the face-down discharge can be performed. Although there is a configuration such as this, this configuration inevitably complicates and upsizes the device due to the long recording paper conveyance path, and also has a high risk of paper jams.

[0005]

[The purpose of the device]

 In view of the above-mentioned circumstances, the present invention proposes a recording paper having an unfixed toner image transferred from a photosensitive drum adhered to the lower surface thereof from the transfer section to the fixing device without disturbing the toner image to the fixing device. An object of the present invention is to provide a recording paper guide structure for an image forming apparatus that can be smoothly introduced and that enables face-down paper ejection with a simple configuration.

[0006]

[Means for solving the problem]

 In order to achieve the above object, a recording paper guide structure of an image forming apparatus according to the present invention comprises a transfer portion arranged above a photosensitive drum and a roller pair in which a roller member is arranged in pressure contact, and the pressure contact portion is a transfer portion. A guide member for guiding the recording paper conveyance direction is provided between the fixing device arranged in the lower region and the fixing device, and the tangent line at the end on the side adjacent to the fixing device is the rotation center of both rollers of the fixing device. It is formed and arranged so as to pass between the two. In addition to the above configuration, the surface of the photosensitive drum of the transfer section and the end of the guide member adjacent to the fixing device are connected by a curve of the natural curvature of the recording paper having the highest rigidity used by the image forming apparatus. The tangent to the curve at the end of the guide member adjacent to the fixing device is formed and arranged so as to pass between the rotation centers of both roller members of the fixing device.

[0007]

[Example of device]

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic structure of an electrophotographic facsimile apparatus which is an image forming apparatus to which an embodiment of a recording paper guide structure of the image forming apparatus according to the present invention is applied. The figure corresponds to a side view, and the right side of the figure is the front side of the device. The illustrated facsimile machine is provided with a paper feed section 30 for feeding or introducing a recording sheet for reception or a document for transmission into the apparatus at the upper rear part of the apparatus main body 10, and a paper feed section for the main body 10 of the apparatus at the front upper side. The upper structural body 20 is pivotally supported at the end on the 30 side (rear side) via the arm 21A. The paper feeding unit 30 includes a cassette mounting unit 31 in which a recording paper cassette 40 accommodating recording paper for reception which is a cut paper is removably mounted at a recording paper introducing portion, and a front end side of the cassette mounting unit 31 of the apparatus. A document holder 32 for a transmission document is provided on the right side of the drawing. In the cassette mounting portion 31, a recording paper introducing roller 33 is arranged at a position corresponding to the upper side of the leading end of the recording paper stored in the recording paper cassette 40 mounted in the cassette mounting portion 31.

The upper structural body 20 has a double structure in which an operation panel 22 is pivotally attached to an upper side of a panel frame 21 at an end portion of the paper feeding section 30 side by a pin 25 so as to be swingable. An arm 21A extending toward the device rear end side of the frame 21 is pivotably attached to the upper rear end of the device main body 10 through an arm 21A. The upper surface of the upper structural body 20 is formed as a gentle inclined surface that becomes lower toward the front end side of the apparatus, and this inclined surface portion serves as an operation portion 23 on which a display panel, operation buttons, etc. are arranged. Inside the upper structure 20, there is provided a reading sensor 50 and a reading head 50 in which a document introducing roller 52 is adjacently arranged on the side of the document holder 32, and the reading head 50 is placed on the document holder 32 of the paper feeding section 30. The transmission document is introduced into the upper structure 20 by the document introduction roller 52 and is conveyed along the path shown by the one-dot chain line in FIG. 1, and the reading sensor 51 reads the written information and discharges it from the front end side of the apparatus. It is a thing.

On the other hand, on the apparatus main body 10 side, there is provided a recording section 60 as an image forming operation section including each operation mechanism section of electrophotography. The recording unit 60 has a photosensitive drum 61, which is rotationally driven at a predetermined peripheral speed by a drive motor (not shown), as a center, and a blade formed of an elastic body is brought into contact with the surface of the photosensitive drum 61 to surround the photosensitive drum 61. A cleaning mechanism 62 that cleans the toner remaining on the surface, a corona charger 63 that uniformly charges the photoconductor on the surface of the photosensitive drum 61, and a laser beam that is turned on and off based on image information to clean the surface of the photosensitive drum 61. A scanning optical system unit 64 that performs exposure scanning, a developing device 65 that attaches toner to a photosensitive member portion that has been latently imaged by exposure to form a toner image, and charges the recording paper to form a toner image on the recording paper. Transfer chargers 66 for transferring are respectively arranged, and the recording paper on which the toner image is transferred by the transfer charger 66 is forward in the conveying direction. A fixing device 67 is formed by arranging constructed by pressing the press roller 67B to the apparatus front side swash Me upper heat roller 67A to be heated at a predetermined temperature.

The upper surface of the recording section 60 constituted by the above-mentioned action mechanism sections is configured to be temporarily lowered toward the front end side of the apparatus as a whole, and the lower surface side of the upper structural body 20 corresponding thereto is also formed. The recording paper guide plate 21E provided on the panel frame 21 is disposed above the developing device 65 at a predetermined interval so as to be close to the developing device 65, and the transfer charger 66 is provided above the developing device 65 between the photosensitive drum 61 and the fixing device 67. A recording paper conveyance path restricting plate 21F, which is an arc-shaped guide member toward the fixing device 67 obliquely below the front end of the apparatus, is provided by being attached to the lower surface of the document lower guide plate 21B of the panel frame 21. With the above configuration, the recording paper is provided between the recording paper guide member (the upper surface of the developing device 65) on the upper surface of the recording unit 60 and the recording paper guide member (the upper recording paper guide plate 21E, the recording paper conveyance path regulation plate 21F) on the lower surface of the upper structure 20. A passage is formed, and a drive roller pair 69 is provided between the developing device 65 and the photosensitive drum 61 so as to sandwich the recording paper passage. The introduction roller 33 of the cassette mounting portion 31, the drive roller pair 69, and the heat roller 67A of the fixing device 67 constitute a recording paper conveyance system, and are rotationally driven at predetermined peripheral speeds by drive motors (not shown), respectively. An image is formed on the recording paper conveyed by the conveying path indicated by the chain double-dashed line in the drawing by the recording unit 60 based on the received information by electrophotography.

That is, the recording papers accommodated in the recording paper cassette 40 are sequentially introduced into the recording paper passage from the upper side by the rotation of the recording paper introduction roller 33 of the cassette mounting portion 31, and the received print or The laser beam from the scanning optical system unit 64, which is modulated based on the image information, causes the surface of the photosensitive drum 61 to perform main scanning (exposure) in the direction of the rotation axis thereof, and at the same time the photosensitive drum 61 is rotated (sub scanning) to cause the photosensitive drum to rotate. An electrostatic latent image is formed on the surface 61 of the electrostatic latent image, and the latent image is developed by a developing device 65 to form a toner image. The toner image is conveyed by a path indicated by a chain double-dashed line in FIG. 1 and charged by a transfer charger 66. The toner image is transferred onto paper, and the fixing device 67 fixes the toner image on the recording paper, and the paper is ejected from the front end side of the device.

Here, the conveyance path of the recording paper conveyed in the recording paper passage is set so as to interfere with a portion of the photosensitive drum 61 facing the transfer charger 66 by a predetermined amount, and the recording paper is conveyed at the portion. The toner image is transferred from the photosensitive drum 61 by being moved (along with the peripheral surface) of the photosensitive drum 61 and being charged by the transfer charger 66. On the front side, the recording paper is separated from the photosensitive drum 61 by its waist (rigidity) and turned upward with respect to the extension direction of the conveying path on the introduction side to the photosensitive drum 61 to regulate the recording paper conveyance path. It comes into contact with the plate 21F, is regulated in the traveling direction by the recording paper conveyance path regulation plate 21F, and is introduced into the fixing device 67 below the front end of the device.

As shown in FIG. 2, in the fixing device 67, at least the pressure contact portion between the heat roller 67A and the press roller 67B is below the horizontal line XX passing through the opposing portion (transfer position) between the photosensitive drum 61 and the transfer charger 66. And the tangent line Q at the pressure contact portion P between the heat roller 67A and the press roller 67B has the recording paper introduction side (photosensitive drum 61 side) as the upper side and the recording paper discharge side as the lower side. It is installed at an angle. The recording paper conveyance path regulation plate 21F has an arc shape (an arc shape in which the front side is lowered) connecting the substantially photosensitive drum 61 and the fixing device 67 obliquely below the front end side of the apparatus, and the side adjacent to the fixing device 67. The tangent line S1 at the end portion of T passes between the heat roller 67A of the fixing device 67 and the rotation centers CA and CB of the press roller 67B, and the opposing position of the photosensitive drum 61 and the transfer charger 66 (transfer position). ) And the end portion: T adjacent to the fixing device 67 with the natural curvature of the recording paper having the highest rigidity used by the image forming apparatus, and the tangent line S2 at the end portion: T to the curve K. The fixing roller 67 is formed and arranged in such a shape as to pass between the center of rotation CA and CB of the heat roller 67A and the press roller 67B of the fixing device 67.

With the configuration of the recording paper conveyance path regulation plate 21F as described above, the recording paper separated from the photosensitive drum 61 after the toner image is transferred from the photosensitive drum 61 is the recording paper conveyance path regulation plate. 21F, and thereafter, the movement path of the recording paper conveyance path regulation plate 21F is regulated downward and the recording paper conveyance path regulation plate 21F is introduced into the fixing device 67. That is, when the rigidity of the recording paper is low, after the leading edge of the recording paper comes off the recording paper transportation path restricting plate 21F, the tangent to the curve of the recording paper transportation path restricting plate 21F at the end: T: S1 Along the outer periphery of the heat roller 67A or the press roller 67B (in the illustrated embodiment, the outer periphery of the press roller 67B), the rollers 67A and 67B are pressed against each other as the press roller 67B rotates. It is smoothly introduced between departments. On the other hand, when the rigidity of the recording paper is high, the rigidity of the recording paper prevents the entire longitudinal direction (transporting direction) from following the recording paper conveyance path regulation plate 21F, and the front end of the recording paper conveyance path regulation plate 21F. When the front end of the recording paper conveyance path regulation plate 21F moves away along the front side of the recording paper conveyance path regulation plate 21F (on the side of the fixing device 67), the end portion of the recording paper conveyance path regulation plate 21F: T and the transfer charger. It is conveyed in a state in which a curve depending on the rigidity of the recording paper and the peripheral surface of the photosensitive drum 61 at the facing portion (transfer position) of 66 are joined by K: the leading end is the outer peripheral surface of the heat roller 67A or the press roller 67B. (The outer peripheral surface of the press roller 67B in the illustrated embodiment) is abutted, and is smoothly introduced between the pressure contact facing portions of the rollers 67A and 67B as the press roller 67B rotates. That is, according to this configuration, the recording paper having low rigidity is guided along the recording paper transportation path restricting plate 21F toward the fixing device 67, and the recording paper transportation path is regulated by the rigidity. The recording paper which does not follow the plate 21F is regulated in its path by an end portion T adjacent to the fixing device 67, so that the recording paper is smoothly introduced into the fixing device 67 (both rollers 67A, 67B can be smoothly bitten into the pressure contact portion of 67B, and thereby the conveyance path is regulated toward the fixing device 67 without supporting the lower surface side of the recording paper on which the unfixed toner image is adhered. It is possible. Further, in the fixing device 67, since the tangent line Q at the pressure contact portion P between the heat roller 67A and the press roller 67B is inclined with the photosensitive drum 61 side as the upper side as described above, the pressure contact between the rollers 67A and 67B is performed. The part P faces the recording paper conveyance direction to facilitate introduction into the fixing device 67. Further, the inclination angle of the tangent line Q is such that the trailing end of the recording paper is the recording paper conveyance path regulation plate 21F. It can be set so that the lower surface (image forming surface) of the toner does not come into contact with the inside of the device and disturbs the unfixed toner image after it hangs off from the inside. In the above embodiment, the tangent line S1 to the curve of the recording paper conveyance path regulation plate 21F at the fixing device 67 side end portion T of the recording paper conveyance path regulation plate 21F is the heat roller 67A and the press roller 67B. Although it is on the upper side (press roller 67B side) of the pressure contact portion, the tangent line: S1 may be set so as to pass between the rotation centers CA and CB of the heat roller 67A and the press roller 67B. As shown in Fig. 3, the rollers 67A and 67B may be formed and arranged so as to be below the pressure contact portion (on the side of the heat roller 67A). In the above embodiment, the present invention is a facsimile machine having a reading head. Although it is applied to the apparatus, it goes without saying that it may be applied to a general image forming apparatus such as a printer.

[0015]

[Effect of the device]

 As described above, according to the recording paper guide structure of the image forming apparatus according to the present invention, the recording paper on which the unfixed toner image transferred from the photosensitive drum adheres to the lower surface can be transferred to the transfer unit without disturbing the toner image. It is possible to guide from the fixing device to the fixing device and smoothly introduce the fixing device to the fixing device, and it is possible to eject the recording paper after fixing face down without inverting it.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of an electrophotographic facsimile machine to which an embodiment of a recording paper guide structure of an image forming apparatus according to the present invention is applied.

FIG. 2 is an explanatory diagram showing a relationship between a recording paper guide and a fixing device.

FIG. 3 is an explanatory view showing another embodiment of the relationship between the recording paper guide and the fixing device.

[Explanation of symbols]

21F ... Recording paper conveyance path regulation plate (guide member) 61 ... Photosensitive drum 66 ... Transfer charger (transfer portion) 67 ... Fixing device 67A ... Heat roller (roller member) 67B ... Press roller (roller member) CA ... Rotation of heat roller Center CB ... Center of rotation of press roller S1 ... Tangent line at end of recording paper transport path regulating plate adjacent to fixing device S2 ... Fixing device for curve of natural curvature of recording paper having rigidity The tangent line at the end on the side adjacent to T ... End (end on the side adjacent to the fixing device)

Claims (2)

[Scope of utility model registration request] 1. An image forming apparatus using an electrophotographic method, comprising a transfer portion arranged on an upper side of a photosensitive drum, and a roller pair in which a roller member is arranged in pressure contact, the pressure contact portion being below the transfer portion. A guide member for guiding the conveying direction of the recording paper is provided between the fixing device arranged in the area, and a tangent line at an end portion of the fixing device adjacent to the fixing device rotates both roller members of the fixing device. A recording paper guide structure for an image forming apparatus, characterized in that it is formed and arranged so as to pass between the centers. 2. The photosensitive drum surface of the transfer section and the end of the guide member adjacent to the fixing device are connected by a curve of natural curvature of the recording paper having the highest rigidity used by the image forming apparatus. A tangent to the curve at an end of the guide member adjacent to the fixing device is formed and arranged so as to pass between rotation centers of both roller members of the fixing device. The recording paper guide structure for an image forming apparatus according to claim 1.