JPH05338832A - Image forming device - Google Patents

Abstract

PURPOSE:To feed thicker paper sheets with large friction or films of less flexibility from the uppermost paper feeding cassette in a stable condition. CONSTITUTION:A first stage paper feeding cassette 5 is made a paper feeding cassette to load and store the paper sheets whose maximum size is 1/2 or below, and set by retracting from the paper feeding side end 6A of the paper feeding cassette 6 of the second or the subsequent stages where the maximum sized paper sheets can be loaded. A paper passage 51 of the paper feeding cassette 5 of the first stage is merged with a merging paper passage 56 of the paper feeding cassette 6 of the second or the subsequent stages between the paper feeding side end 5A of the paper feeding cassette 5 and the paper feeding side end 6A of the paper feeding cassette 6 of the second or the subsequent stages. The paper feeding cassette of the third or the subsequent stages are not indicated in the figure.

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, a printer and a facsimile.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile, a plurality of sheet feeding cassettes arranged vertically are provided in an image forming apparatus main body, and sheets in each sheet feeding cassette are fed to an image forming section. An image forming apparatus that selectively feeds paper is known.

In the image forming apparatus of this system, since a plurality of sheet feeding cassettes for accommodating sheets of different sizes are provided in the main body of the image forming apparatus, it is possible to save the trouble of replacing the sheets. Further, since a plurality of paper feed cassettes are arranged vertically in the image forming apparatus body, there is an advantage that the installation area of the image forming apparatus body can be reduced.

Incidentally, each paper feed cassette in the image forming apparatus of this system is of a front loading type in which it is taken in and out from the front side of the image forming apparatus main body.

FIG. 3 shows the overall construction of a conventional color image forming apparatus (copying machine) adopting this method.

In this color image forming apparatus, the photosensitive drum 2 and the transfer drum 3 are provided in the upper portion of the main body 1 of the image forming apparatus.
And the like, and a plurality of paper feed cassettes 5 in which sheets of different sizes are stacked and stored in the lower portion of the image forming apparatus main body 1.
6, 7, 9, etc. are arranged.

The photosensitive drum 2 is designed to rotate clockwise, and a primary charger 10 for uniformly charging the rotating photosensitive drum 2 and an electrostatic latent image on the photosensitive drum 2 are provided around the photosensitive drum 2. With a magenta developing device 11, a cyan developing device 12, a yellow developing device 13, a black developing device 15, a cleaning blade 16 for scraping off the toner remaining on the photosensitive drum 2, and a cleaning blade 16. A collecting roller 17 for collecting the taken toner, a primary charging device 10, and developing devices 11, 12, 1
A potential sensor 19 for detecting the bias state of the photosensitive drum 2 is provided to control the bias applied to the electrodes 3 and 15.

The original 21 placed on the original glass 20 of the image forming apparatus main body 1 is illuminated from below by an illumination lamp 22. Then, the image of the document 21 enters the lens 27 through the reflecting mirrors 23, 25, and 26 that move at a predetermined speed, and forms an optical image on the image pickup device 29. The signal photoelectrically converted by the image pickup device 29 is input to the laser scanner 31 via the image processing unit 30. The laser light L emitted from the laser scanner 31 is sent to the image writing position a of the photosensitive drum 2 via the reflection mirror 32.

As a result, the images of the document 21 are sequentially written on the photosensitive drum 2 which is rotating clockwise while being uniformly charged by the primary charger 10, and an electrostatic latent image is formed. Then, the electrostatic latent image is transferred to each developing device 11,
The image is visualized with 12, 13, and 15 color toners.

The transfer drum 3 is formed of a plastic film in a cylindrical shape and rotates counterclockwise.
At a predetermined position of the transfer drum 3, the sheets fed from any one of the sheet feeding cassettes 5, 6, 7, and 9 are transferred to the transfer drum 3.
Adsorption charging brush 33, an adsorption roller 35 for adsorbing the toner image on the photosensitive drum 2, a transfer brush 36 for bias-transferring the toner image on the photosensitive drum 2 to the sheet adsorbed on the transfer drum 3, and an adsorption on the transfer drum 3. A static eliminator 37 for removing static electricity from the surface of the sheet being removed, and a separation claw 39 for scooping and removing the static eliminated sheet from the transfer drum 3 are provided.

The sheet fed from any one of the sheet feeding cassettes 5, 6, 7, and 9 is sent between the transfer drum 3 rotating counterclockwise and the suction roller 35, and the suction charging brush and the suction roller. And 35, are sequentially attracted to the transfer drum 3. Then, the toner images on the image forming drum 2 are sequentially bias-transferred onto the sheet attracted to the transfer drum 3 by the transfer brush 36 (image forming unit).

The sheet after the transfer of the toner image is discharged by the static eliminator 3.
The charge is removed by 7 and the transfer drum 3 is separated by the separating claw 39.
It is peeled off from the sheet and is sent to the nip portion of the fixing roller pair 41 while being sucked by the conveying belt 40. Fusing roller pair 4
The sheet sent to No. 1 is pressed and heated to fix the toner image, and then discharged by a pair of discharge rollers 42 onto a discharge tray (not shown) outside the apparatus.

After the transfer of the toner image, the toner adhering to the photosensitive drum 2 is scraped off by the cleaning blade 16 and collected by the collecting roller 17.

The paper feed cassettes 5, 6, 7, and 9 are all paper feed cassettes capable of stacking and storing sheets of the maximum size, and are arranged at a predetermined interval in the vertical direction. In this case, the paper feed side end 5 of each paper feed cassette 5, 6, 7, 9
A, 6A, 7A and 9A are located at the same position.

The paper feed cassettes 5, 6, 7, and 9 are slidably fitted into the left and right rails 43A and 43B of the image forming apparatus main body 1 so that the left and right guides 45A and 45B are slidably fitted to each other. The image forming apparatus main body 1 can be put in and taken out from the front side. That is, the paper feed cassettes 5, 6, 7, 9 slide in the direction perpendicular to the paper surface.

The sheets stacked and stored in the respective sheet feeding cassettes 5, 6, 7 and 9 are fed out by the sheet feeding rollers (pickup rollers) 46, 47, 49 and 50 which rotate counterclockwise. Passages 51, 52, 53, 5
The sheet is fed between the transfer roller 3 and the suction roller 35 through the sheet feeding path 5 and the merged sheet passage 56.

The sheets sent out from the sheet feeding cassettes 5, 6, 7, and 9 are first paired with the first registration rollers 57 and 5.
The first registration roller pair 57, 59, 60, 61 and the conveyance roller pair 62, 63, which are fed to 9, 60, 61 and straightened there, and then start rotating at appropriate timing.
Is sent to the second pair of registration rollers 65, where the skew is finally corrected. Then, the sheet is sent between the transfer roller 3 and the suction roller 35 by the second pair of registration rollers 65 which starts rotating at an appropriate timing.

By the way, in the case of this color image forming apparatus,
Since the large-diameter photosensitive drum 2 and the transfer drum 3 are installed in the image forming apparatus main body 1, a space for installing a plurality of sheet feeding cassettes 5, 6, 7, and 9 is provided as compared with a normal single-color image forming apparatus. It is greatly restricted. Therefore, conventionally, when installing as many paper feed cassettes 5, 6, 7, 9 as possible in a limited space in the image forming apparatus main body 1, the paper feed roller 46 of the uppermost paper feed cassette 5 is installed. Small diameter,
The curvature of the curved portion of the seat passage 51 is reduced.

In this way, the sheet feeding roller 46 of the uppermost sheet feeding cassette 5 is made to have a small diameter and the curvature of the curved portion of the sheet passage 51 is made small by the merging sheet passage 56. This is because the space for forming the sheet passage 51 is limited and the space for forming the sheet passage 51 is limited.

The transfer drum 3 used in the color image forming apparatus must be capable of winding a maximum size sheet. For example, when using a maximum size sheet of 420 mm in length, a diameter of 160 mm is used. Transfer drum 3
Will be required. Further, the photosensitive drum 2 also has to have the same diameter as the transfer drum 3 in order to prevent the image displacement.

[0021]

However, in the conventional color image forming apparatus described above, a small-diameter paper feed roller 46 is used in the uppermost paper feed cassette 5, or a sheet passage 51 is used.
Since the curvature of the curved portion is small, when a thick paper having a large friction or a strong film is fed from the uppermost sheet feeding cassette 5, there is a possibility that a feeding failure or a jam may occur. ..

For this reason, the conventional color image forming apparatus is provided with a manual sheet feeding section (not shown) having a linear sheet path (straight path) for feeding thick paper or film. Paper cassettes other than the top 6,
I had to deal with cases where 7, 9 could not be used.

Further, such a problem is not limited to the color image forming apparatus, and, for example, in the case of increasing the number of paper feed cassettes installed in the main body of the image forming apparatus in a limited space in a normal single color image forming apparatus. Occurs similarly to.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and even when as many sheet feeding cassettes as possible are installed in the limited space of the main body of the image forming apparatus, the uppermost stage is provided. It is an object of the present invention to provide an image forming apparatus capable of stably feeding thick paper having a large amount of friction, a strong film, or the like from the paper feeding cassette in a stable state without a paper feeding failure or a jam.

[0025]

SUMMARY OF THE INVENTION The present invention comprises a plurality of paper feed cassettes (5, 6, 7, 9) vertically arranged in an image forming apparatus (1) main body, and an image forming unit (2). , 3) to the image forming apparatus of the type that selectively feeds the sheets in each of the paper feed cassettes (5, 6, 7, 9).

In order to achieve the above object, the present invention provides, as each of the paper feed cassettes (5, 6, 7, 9), a normal paper feed cassette (6, 7, 7) capable of stacking and storing sheets of the maximum size. 9) and a small paper feed cassette (5) that is not capable of stacking and storing sheets of the maximum size, and the small paper feed cassette (5) is connected to the normal paper feed cassettes (6, 7,
9) is installed at the uppermost stage in a state retracted from the feeding side ends (6A, 7A, 9A), and the normal paper feeding cassette (6, 6).
Confluent sheet passage (5
6) and the merging portion (66) of the sheet path (51) of the sheets fed from the small-sized sheet feeding cassette (5) to the feeding side end (6A) of the normal sheet feeding cassette (6, 7, 9). , 7A,
9A) and the feeding side end (5) of the small paper feeding cassette (5)
It is characterized in that it is arranged between A).

The normal paper feed cassette (6, 7,
The confluence section is located below the image forming section (2, 3) located between the feeding side end (6A, 7A, 9A) of 9) and the feeding side end (5A) of the small sheet cassette (5). (66) is arranged.

[0028]

According to the above construction, the sheet passage (51) of the sheet fed from the small sheet feeding cassette (5) installed at the uppermost stage is provided on the feeding side of the normal sheet feeding cassette (6, 7, 9). Between the end (6A, 7A, 9A) and the feeding side end (5A) of the small paper feed cassette (5), the normal paper feed cassette (6, 7, 9)
It merges with the merging passage (56) for the sheets fed from.

Therefore, the uppermost small paper feed cassette (5)
The sheet passage (51) of the normal paper feed cassette (6, 7,
Since the space for forming the merged sheet passage (56) of 9) is not restricted, the curvature of the curved portion can be increased. Further, the paper feed roller (46) of the uppermost small paper feed cassette (5) is also the normal paper feed cassette (6).
Since there is no restriction on the space for installation in the merged sheet passage (56) of 7, 9), a large-diameter sheet feeding roller can be used.

As a result, it is possible to stably feed thick paper having a large amount of friction, a strong film, or the like from the uppermost small paper feed cassette (5) without causing a paper feed failure or jam.

The reference numerals in the parentheses are for reference to the drawings and do not limit the structure in any way.

[0032]

Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 1 shows the overall configuration of a color image forming apparatus (copier) according to Embodiment 1 of the present invention.

In this color image forming apparatus, the same members as those of the above-described conventional color image forming apparatus are designated by the same reference numerals, and the description of those which are structurally and functionally unchanged will be omitted.

In this color image forming apparatus, the paper feed cassettes 6, 7 and 9 installed in the second, third and fourth stages are capable of accommodating sheets of the maximum size. (Regular paper feed cassette), the paper feed cassette 5 installed in the first stage (top stage) is set to the maximum size of 1
A paper feed cassette (small paper feed cassette) for stacking and storing sheets of / 2 or less is used.

Then, the first-stage paper feed cassette 5 is
The sheet feeding cassettes 6, 7, 9 of the second, third, and fourth stages are installed in a state of being retracted from the feeding-side ends 6A, 7A, 9A. Here, the non-feeding side end 5B of the first-stage sheet feeding cassette 5 is replaced with the anti-feeding side end 6B of the second-stage, third-stage, and fourth-stage sheet feeding cassettes 6, 7, and 9. , 7B, 9B.

Further, the sheet passage 51 of the sheet fed from the first-stage sheet feeding cassette 5 is fed through the sheet feeding side end 5A of the sheet feeding cassette 5 and the sheet feeding cassette 6 of the second stage. Side edge 6
Between A, the merged sheet passage 5 for the sheets fed from the second, third, and fourth sheet feeding cassettes 6, 7, and 9
Joined with 6. A second pair of registration rollers 65 is installed at this junction 66.

In this case, the merging portion 66 of the sheet passage 51 and the merging sheet passage 56 is located below the photosensitive drum 2 and the transfer drum 3 for image formation.

With this structure, the sheet passage 51 of the first-stage sheet feeding cassette 5 has the second-stage and third-stage sheets.
The space for formation is not restricted by the merging sheet passages 56 of the sheet feeding cassettes 6, 7, 9 in the fourth and fourth stages, and therefore the curvature of the curved portion can be increased.

Further, the paper feed roller 46 of the first-stage paper feed cassette 5 is provided by the confluent sheet passage 56 of the second-stage, third-stage, and fourth-stage paper feed cassettes 6, 7, and 9. The space for installation is not restricted, and thus a large diameter feed roller can be used.

In the case of this color image forming apparatus, the distance bc from the sheet front end b of the first sheet feeding cassette 5 to the transfer position c including the resist feed amount is set to the image front end position d of the photosensitive drum 2 and the transfer position. Since it is possible to make the distance smaller than the distance dc to c (dc> bc), the first sheet fed from the first-stage sheet feeding cassette 5 is the photosensitive drum after the photosensitive drum 2 starts rotating. Even if the paper is fed at the same speed as the peripheral speed of 2, the transfer position c can be sufficiently reached. Therefore, the copying time of the first sheet fed from the first-stage sheet feeding cassette 5 can be shortened and the sequence can be simplified.

Even in the case where a sheet feeding cassette for stacking and storing 1/2 or less sheets of the maximum size is used in the first stage sheet feeding cassette 5 as in the present color image forming apparatus, for example, the maximum size A3 is used. The sheet that is mainly used in the image forming apparatus that uses the sheet is an A4 size sheet,
Moreover, since the sheets of the maximum size A3 can be fed by the sheet feeding cassettes 6, 7, 9 of the second, third, and fourth stages, there is no problem in feeding the sheets of the maximum size. ..

Therefore, when the number of paper feed cassettes is large and the maximum size sheet can be fed, the paper feed cassette 6 of the second stage is the same as the paper feed cassette 5 of the first stage. Can be configured. <Embodiment 2> In Embodiment 2 shown in FIG. 2, the construction of each of the paper feed cassettes 5, 6, 7 and 9 (paper feed cassettes 7 and 9 are omitted) of the above Embodiment 1 is a normal monochromatic image forming apparatus When applied to a copying machine.

In the case of the present monochromatic image forming apparatus, the sheets fed from the sheet feeding cassettes 5, 6, 7 and 9 are transferred to the photosensitive drum 67 and the transfer charger 6 by the second registration roller pair 65.
It is sent between 9 and.

[0044]

As described above, in the image forming apparatus of the present invention, a small paper feed cassette that cannot store the maximum size sheets in the uppermost paper feed cassette is used.
Since the paper feed roller and the sheet passage are arranged at a position that is not affected by the confluent sheet passage of other paper feeding cassettes capable of stacking and storing the maximum size sheets, a large-diameter paper feeding is performed in the uppermost paper feeding cassette. A roller can be used, and the curvature of the curved portion of the sheet path of the uppermost sheet feeding cassette can be increased.

Therefore, even when as many paper feed cassettes as possible are installed in the limited space in the main body of the image forming apparatus, the thick paper and the strong stiffness from the uppermost paper feed cassette are increased. You can feed the film in a stable state.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing the overall configuration of a color image forming apparatus (copying machine) according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view showing the main configuration of a single-color image forming apparatus (copying machine) according to a second embodiment of the present invention.

FIG. 3 is a vertical cross-sectional side view showing the overall configuration of a conventional color image forming apparatus (copier).

[Explanation of symbols]

 1 Image Forming Apparatus Main Body 2 Photosensitive Drum (Image Forming Section) 3 Transfer Drum (Image Forming Section) 5 Paper Feed Cassette (Small Paper Feed Cassette) 6, 7, 9 Paper Feed Cassette (Normal Paper Feed Cassette) 5A, 6A, 7A , 9A Feeding side end 51 Seat passage 56 Confluence sheet passage 66 Confluence part

Claims (2)

[Claims] 1. An image forming apparatus having a plurality of sheet feeding cassettes arranged vertically in an image forming apparatus main body and selectively feeding the sheets in each of the sheet feeding cassettes to an image forming unit. As each of the paper feed cassettes, a normal paper feed cassette capable of stacking and storing the maximum size sheets and a small paper feed cassette not capable of stacking and storing the maximum size sheets are used. It is installed at the uppermost stage in a state of retracting from the sheet feeding side end of the paper cassette, and the merging sheet passage of sheets fed from the normal sheet feeding cassette and the sheet passage of sheets fed from the small sheet feeding cassette. The image forming apparatus is characterized in that the merging portion is disposed between the feeding side end of the normal sheet feeding cassette and the feeding side end of the small sheet feeding cassette. 2. The merging section is arranged below the image forming section located between the feeding side end of the normal sheet feeding cassette and the feeding side end of the small sheet feeding cassette. The image forming apparatus described.