JP2845382B2 - Paper feeder for image forming equipment - Google Patents

Description

The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile that forms an image on a recording medium (sheet material) such as paper, an OHP sheet, and an envelope. The present invention relates to a sheet feeder provided in the printer.

(B) Conventional technology FIGS. 6 (a), 6 (b) and 6 (c) show a laser beam printer using electrophotographic recording means, which is a typical image forming apparatus. is there.

In the image forming apparatus, as shown in FIG. 6A, for the purpose of obtaining the reliability of conveyance of the recording medium,
A method of transporting 0 linearly is adopted. However, in this method, the paper feed cassette 102 and the paper discharge tray 103 are installed at the entrance and the exit of the image forming apparatus main body 101. There is a problem that the installation space of the device is substantially increased.

From this, FIGS. 6 (b) and 6 (c)
A U-shaped or S-shaped image forming apparatus in which the transport path of the recording medium 100 is reversed as described above has been developed. In this type, a substantial installation area of the image forming apparatus is small.

On the other hand, in the image forming apparatus, if the recording medium 100 is not correctly sent to the image forming section in the main body 101 of the image forming apparatus, image distortion or the like occurs.

For this reason, in the image forming apparatus, generally, when the recording medium 100 is conveyed along the conveyance path, the reference side end surface of the recording medium 100 is pressed against the conveyance reference guide of the image forming apparatus main body 101 by the oblique feeding roller. While transporting,
Skew of the recording medium 100 is prevented.

(C) Problems to be Solved by the Invention However, in the image forming apparatuses (FIGS. 6 (b) and 6 (c)) in which the transport path of the recording medium 100 is inverted in a U-shape or an S-shape. In this case, the height of the image forming apparatus main body 101 tends to increase as compared with an image forming apparatus (FIG. 6 (a)) having a straight transport path. Image forming apparatus main body 101
Can be reduced by reducing the radius of an equivalent circular arc that bends and reverses the recording medium 100. However, when the radius of the circular arc is reduced, for example, as shown in FIG.
There is a possibility that the recording medium 100 may be pulled or slack in the gap between the guides 107 due to the difference in the transport speed between the transport rollers 105 and 106 in the section, and there is a problem in the transport reliability.

Also, it is necessary to completely match the position of the end face regulating member for regulating the transport reference side end face of the recording medium 100 provided in the paper feed cassette 102 with the position of the transport reference guide in the image forming apparatus main body 101. In some cases, the recording medium 100 may be damaged. This will be described with reference to FIG. 7 (a). If the position of the end surface regulating member 109 and the position of the conveyance reference guide 110 do not coincide with each other and a gap ₁ is formed between them, the recording medium 100 is When the recording medium 100 is conveyed while being pressed in the arrow direction by the skew feeding roller 111, the end face of the recording medium 100 is
09 breaks or burrs occur.

Also, as shown in FIG.
0 is located inside the position of the end surface regulating member 109 by △ ₂ , the end surface of the recording medium 100 is
There is a problem that burrs are generated by rubbing at the 10 C position.

Therefore, the present invention has been made in view of the above circumstances, and in order to suppress the height of the image forming apparatus main body, even if the radius of the equivalent arc for bending and reversing the recording medium is reduced, the recording medium In the reversing part, the recording medium is not degraded in transport reliability, and there is no occurrence of tension or slack.
Even if the position of the end face regulating member on the paper feed cassette side and the position of the conveyance reference guide on the image forming apparatus main body side are misaligned, the conveyed recording medium is damaged by the end face regulating member or the like due to the end face regulating member or the like. It is an object of the present invention to provide a paper feeder for an image forming apparatus, which does not cause any problem.

(D) Means for Solving the Problems In order to achieve the above object, the present invention provides a method for accommodating a plurality of recording media and contacting one side end of the recording media with the recording media. A sheet cassette provided with an end face regulating member for regulating movement of the recording medium in a direction perpendicular to the transport direction; and a sheet feeding means for separating and feeding the recording medium one by one from the sheet cassette. A feed roller that feeds the recording medium fed by the feeding unit; and a sheet feeding device that contacts the one side end of the recording medium that is fed by the feeding roller. A conveyance reference guide that regulates the movement of the recording medium in a direction perpendicular to the conveyance direction, and presses against the conveyance roller to pinch the recording medium with the conveyance roller, while the one side end is the conveyance end; Abuts reference guide And a bending guide for bending and guiding the recording medium fed by the paper feeding means so as to be wound around the transport roller. It is a feature.

Also, a skew feeding roller is used as the skew feeding means.

(E) Operation According to the above configuration, the recording medium separated and fed one by one from the sheet feeding cassette by the sheet feeding means is conveyed by the conveying rollers. Further, the recording medium is sandwiched together with the conveyance roller by pressing the oblique feeding means against the conveyance roller, and the recording medium is
The recording medium is fed obliquely in a direction in which it comes into contact with one side end of the recording medium and restricts movement of the recording medium in a direction perpendicular to the conveying direction.

Further, the recording medium fed from the paper feed cassette is bent by a bending guide so as to be wound around a conveying roller, and the recording medium is bent in this manner, whereby the position of the end face regulating member of the paper feeding cassette and the conveyance reference guide are adjusted. The recording medium is conveyed while absorbing the deviation of the position.

(F) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an overall configuration of a laser beam printer (LBP) using an electrophotographic means provided with a paper feeder of the present invention.

In FIG. 1, reference numeral 1 denotes a drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) which is disposed in a process cartridge 2 and is driven to rotate at a predetermined peripheral speed around a support shaft 12; The surface is provided with a photoconductor mainly composed of an organic or inorganic photoconductor layer.

The photosensitive drum 1 is uniformly charged at a predetermined positive or negative potential by a primary charger (not shown) in the process cartridge 2 during the rotation thereof, and is then subjected to laser beam scanning exposure L by a laser scanner 5 at the exposure unit 3. Scanning writing of target image information is received. As a result, an electrostatic latent image corresponding to the target image information is sequentially formed on the outer peripheral surface of the photosensitive drum 1.

Reference numeral 6 denotes a laser beam turning mirror for deflecting the laser beam L output from the laser scanner 5 to the exposure unit 3 for the photosensitive drum 1.

The photosensitive drum surface on which the latent image is formed is then supplied with a developing material (toner) by a developing device (not shown) in the process cartridge 2 so that the toner is visualized as an image.

Next, the toner image is sequentially transferred onto a transfer material (recording medium) P surface fed one by one from a paper feed mechanism 8 between the transfer roller 7 and the photosensitive drum 1 in a process of passing the position of the transfer roller. Transcribed.

The transfer of the toner image from the surface of the photosensitive drum to the surface of the transfer material P is performed by the transfer roller 7 disposed on the back surface of the transfer material P being charged with a polarity opposite to the charged electrode property of the toner image. The transfer material P that has passed the position of the transfer roller 7 is then disposed downstream of the transfer roller 7 and is separated from the surface of the photosensitive drum by being subjected to charge removal by a separation charge removing needle 9 to which a potential having a polarity opposite to that of the transfer roller 7 is applied. The unfixed toner image transferred to the fixing device 10 and transferred to the transfer material P is fixed as a permanent fixed image.

Then, the transfer material P on which the image has been fixed is transferred to the discharge roller pair 11.
And is discharged to the discharge tray 12.

On the other hand, the surface of the photosensitive drum after the transfer of the toner image is repeatedly used for image formation after the adhered matter such as untransferred toner is removed by a cleaning device (not shown) in the process cartridge 2.

Next, the paper feeder of the present invention will be described with reference to FIG.

With respect to the transfer material P loaded and stored in the paper feed cassette 13, only the uppermost sheet of the loaded transfer material P is given a conveying force by the rotation of the paper feed roller 15, and only one uppermost sheet is separated by the separating sheet 16, and the transfer sheet P is separated in the a direction. Transported to At this time, a predetermined pressing force is applied between the transfer material P and the paper feed roller 15 by the cooperation of the middle plate 17 and the pressure spring 19.

The separated transfer material P is an arc-shaped guide of the sheet cassette 13.
13a, the first skew feeding roller 20 and the conveying roller 21
The transfer material P is transported in synchronism with the rotation speed from a drive source (not shown), and the second oblique transport roller 22 and the transport roller
After passing through the space 21, the image reaches the image forming section between the photosensitive drum 1 and the transfer roller 7. When the transfer material P is transported on the outer peripheral surface of the transport roller 21, the transfer material P is reversed at the radius of the transport roller 21. At this time, the other portion of the transfer material P is guided by the reversing guide 31 which forms a bending guide together with the arc-shaped guide 13a of the paper feed cassette 13.

The first and second skew feeding rollers 20 and 22 are the transfer reference end faces P of the transfer material P.
a in the direction in which a is pressed against the transport reference guide 25 on the printer main body (image forming apparatus main body) 23 side, θ ₁ = 1 ゜, θ ₂
= 4 ° (FIG. 3), and the conveyance roller 21 is driven at a predetermined pressure by the cooperation of the first skew arm 26, the second skew arm 27, and the pressing spring 30 (FIG. 1). Is pressed against.

In the case of this embodiment, the transport reference guide on the printer main body 23 side
The position of 25 and the position of the end face regulating member 32 on the side of the paper feed cassette 13 are arranged with a gap _{３ 3} = 1.5 mm as shown in FIG.

In the paper feeder of the present embodiment having the above configuration, even if there is a gap # ₃ between the transport reference guide 25 on the printer main body 23 and the end surface regulating member 32 on the paper feed cassette 13, the transfer material P There is no damage such as breaks or burrs. This is because, even as the transfer material P is constrained is sandwiched by the first oblique feed roller 20 and the transport roller 21 at P ₁ position as shown in FIG. 4, since the transfer material P has a curvature such as indicated by R , it is possible to absorb the gap △ ₃ in this R portion, the force F applied to the end surface of the transfer material P by the end face restricting member 32 in the sheet feeding cassette 13 is because small.
If the rigidity of the transfer material P and the transfer material P at the P ₂ position by extending the transfer material P on a straight line is constrained stronger and will force F becomes sufficient force to cause damage to the end face of the transfer material P,
Burrs and breaks will occur on the end surface 12 of the transfer material P.

Further, in the configuration of the present embodiment, the transport reference guide 25 on the printer main body 23 and the end face regulating member 32 on the paper cassette 13 side
Since the positional relationship as shown in FIG. 7 (b) is not established, the tip of the transfer material P does not break at the portion C.

Further, in the case of the present embodiment, since the transfer material P is reversed on the outer peripheral surface of one transport roller 21, the transport speed during the reverse is constant. Therefore, the transfer material P is not pulled or sagged.

In the present embodiment, the claw separation method is used for the sheet feeding / conveying unit, but it goes without saying that another separation method can be used.

Also, a skew feeding roller is used as pressing means for skewing the transfer material P.
The spiral grooves 35 may be formed in the inclined rollers 20, 22 as shown in FIG. This groove 35
May be formed on the transport roller 21.

Also, the number of the skew feeding rollers 20, 22 as the skew feeding means is not limited to two. Then, the transfer force of the transfer material P may be applied not to the transfer roller 21 but to the skew feeding rollers 20 and 22.

Further, the gap △ ₃ between the conveyance reference guide 25 on the printer main body 23 and the end face regulating member 32 on the paper cassette 13 is set to 1.5 mm. It can be transported without burrs or the like.

(G) Advantageous Effects of the Invention As described above, according to the present invention, when a recording medium is reversed, the recording medium is conveyed while being skewed in a direction abutting on a conveyance reference guide by a conveyance roller and a skew feeding means. By doing so, the transport speed when the recording medium is reversed can be made constant. Accordingly, in order to suppress the height of the main body of the image forming apparatus, even if the radius of the equivalent arc for bending and reversing the recording medium is reduced, the transport reliability of the recording medium in the recording medium reversing unit is impaired. Tightening and sagging can be prevented from occurring.

Further, when the recording medium fed from the paper feed cassette is conveyed to the conveyance roller, the recording medium is bent by a bending guide so as to wind around the conveyance roller, so that the recording medium is positioned at the position of the end face regulating member of the paper feed cassette. The conveyance can be performed while absorbing the displacement of the position of the conveyance reference guide. This allows
Even if the position of the end face regulating member on the paper feed cassette side and the position of the conveyance reference guide are misaligned, it is possible to prevent the recording medium being conveyed from being damaged by the end face regulating member or the like due to the end face regulating member or the like. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing the overall configuration of a laser beam printer provided with a paper feeder according to the present invention, FIG. 2 is an enlarged perspective view of the paper feeder, and FIG. FIG. 4 is an enlarged plan view, FIG. 4 is a perspective view showing a feeding state of a transfer material fed and conveyed by the sheet feeding / conveying apparatus, and FIG. 5 is a modified structure example of a skew feeding roller used in the sheet feeding / conveying apparatus. FIGS. 6 (a) to 6 (c) are longitudinal sectional front views showing a laser beam printer as a conventional image forming apparatus, and FIGS. 7 (a) and 7 (b) are FIG. 9 is a plan view showing a state in which a recording medium is fed and conveyed by a conventional sheet feeding device. 13 paper feed cassette, 15 paper feed roller, 16 separating paper, 20 first skew feeding roller (pressing means), 21 transport roller, 22 second skew feeding roller (pressing means) ), 23: Printer main body (image forming apparatus main body), 25: Transport reference guide, 32
... End face regulating member, P ... Transfer material (recording medium), Pa ...
... Reference end face of conveyance, R: Curvature of transfer material, △ ₃ : Gap between conveyance reference guide and end face regulating member.

Claims (2)

(57) [Claims] An end surface regulating member for accommodating a plurality of recording media and abutting against one side end of the recording media to regulate movement of the recording media in a direction perpendicular to the transport direction. A sheet feeding cassette of an image forming apparatus having a sheet feeding cassette and a sheet feeding unit that separates and feeds the recording medium one by one from the sheet feeding cassette. A transport roller that transports the recording medium; and a transport reference guide that contacts the one side end of the recording medium transported by the transport roller and regulates movement of the recording medium in a direction orthogonal to the transport direction. Oblique feeding means for pressing the recording medium in contact with the conveyance roller and nipping the recording medium together with the conveyance roller, while obliquely feeding the recording medium in a direction in which the one side end contacts the conveyance reference guide; By the paper feeding means And a bending guide for bending and guiding the fed recording medium so as to be wound around the transport roller. 2. A sheet feeding and conveying device for an image forming apparatus according to claim 1, wherein a skew feeding roller is used as said skew feeding means.