JPH0922202A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electrical contact defect, and to prevent occurrence of the printing defect derived from the transfer defect, by respectively providing an expanded part expanding inward an image forming device on a supporting shaft and a bearing part. SOLUTION: A transfer roller 19 is electrically connected to a high voltage power source 18 through such as a power feeding terminal 30, the supporting shaft 22, the transfer roller shaft 21 and the transferring part 20. The supporting shaft 22 and bearing part 36 respectively disposed on both ends of the transfer roller 19, is respectively provided with the expanded supporting shaft 23 and the expanded bearing part 37 expanding inward the device. A gap formed between the expanded supporting shaft 23 and the expanded bearing part 37, is allowed to expand toward the device inside, and the lower half of the gap inclines downward. Then, the toner 9 entering into the gap formed between the expanded supporting shaft 23 and the expanded bearing part 37 is moved in the rotary direction of the transfer roller 19, accompanying rotation of the transfer roller 19, while moved along a downward, inclination of the expanded bearing part 37 expanding inward the device, and discharged into the image forming device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a transfer roller of an image forming apparatus.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIG.

Reference numeral 1 denotes a transfer roller for transferring a toner image formed on a photosensitive drum (not shown) onto a sheet, which is formed integrally with a cylindrical transfer portion 2 and the center of the transfer portion 2. The transfer roller shaft 3 and the support shaft 4 are formed at both ends of the transfer roller shaft 3 in the longitudinal direction.

Reference numerals 5 denote bearings attached to left and right side frames (not shown). The bearings 5 are circles for rotatably supporting the support shafts 4 provided at both ends of the transfer roller 1. A shaft support portion 6 formed of a columnar hole is provided so as to penetrate the center portion.

Further, a power supply voltage 18 is connected to the transfer roller 1, and the power supply voltage 18 gives electric charges to a sheet (not shown). A potential difference is generated between the charged sheet and the photosensitive drum (not shown), and the toner image formed on the photosensitive drum is transferred to the sheet due to this potential difference.

A spacer 7 is arranged between the transfer roller 1 and the bearing 5 and is inserted into the support shaft 4.
In operation, for example, when the toner is attached to the electrostatic latent image formed on the photosensitive drum (not shown), the toner 9 scattered in the image forming apparatus is supported by the transfer roller 1. It is intended to prevent entry into the gap between the shaft 4 and the shaft support 6.

[0007]

As described above, in the conventional image forming apparatus, a small amount of toner 9 scattered in the image forming apparatus during operation is supported on both ends of the transfer roller 1. Entering into the gap formed between the shaft 4 and the shaft support 6, contact failure occurs between the bearing 35 connected to the high-voltage power supply 18 and the transfer roller 19, and it occurs between the photosensitive drum and the paper. There is a variation in the potential difference. Therefore, there is a problem that a transfer failure occurs and a print failure occurs.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an image forming apparatus which prevents the occurrence of printing defects due to transfer defects.

[0009]

In order to achieve the above-mentioned object, an image forming apparatus of the present invention comprises a transfer roller arranged around a photoconductor and both ends of the transfer roller in the longitudinal direction. In an image forming apparatus comprising formed support shafts and bearings having shaft support portions that rotatably support the support shafts, the transfer roller is provided on the support shaft and the shaft support portion on the transfer roller side, respectively. It is characterized in that an expanding portion that expands toward the side is provided.

A supporting shaft and a shaft supporting portion respectively provided at both ends of the transfer roller are provided with a expanding supporting shaft and a expanding shaft supporting portion which are expanding portions for expanding toward the inside of the apparatus. Therefore, the gap formed between the expansion support shaft and the expansion shaft support portion is expanded toward the inside of the apparatus, and the lower half of the gap is inclined downward. Therefore, the toner, which has entered the gap between the expansion support shaft and the expansion shaft support, moves in the rotation direction of the support shaft along with the rotation of the transfer roller and also moves along the downward inclination, and the image forming apparatus. Is discharged inside.

Further, since the supporting shaft of the transfer roller and the shaft supporting portion are provided with the expanding portions, respectively, the contact area between the supporting shaft of the transfer roller and the shaft supporting portion is expanded, and the electrical connection is made more reliable. became.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS.

FIG. 4 is a cross-sectional view showing a general image forming apparatus. The image forming apparatus 41 includes a cover 44 which is attached to an upper surface of a main body case 52 so as to be openable and closable, and a rear portion of the main body case 52. It has a paper feed tray 15 standing upright in an inclined state, and a paper discharge port 48 formed on the front surface of the main body case 52. Further, the image forming apparatus 41 has, as main components inside thereof, a sheet conveying system 42 (not shown), a laser unit 12, a process unit 11, and a photosensitive drum provided in the process unit 11. The transfer roller 19 is in contact with the fixing roller 13 and the fixing device 47.

In the process unit 11, a charging unit 54, an exposing unit 60, a developing unit 57 and a cleaner 55 are provided in a casing-like unit case 43 so as to surround the photosensitive drum 13 and the periphery of the photosensitive drum 13. It is unitized by being attached.

The carrying system 42 is formed by a paper carrying path 17 and means for carrying the paper arranged along the carrying path 17. The means for transporting the paper is a paper feed roller 1 for feeding the paper stored in the paper feed tray 15.
4 separates and feeds the sheet into the conveying path, and the separated and fed sheet is conveyed by the conveying roller 36, the photosensitive drum 13, and the transfer roller 19.
Roller pair consisting of a fixing device 47 and a discharge roller 56
The structure is such that the sheets are sequentially conveyed by and are discharged from the sheet discharge port 48.

The laser unit 12 is a laser unit (not shown).
The laser light emitted from the diode is deflected and scanned by the polygon mirror 53 driven by the polygon motor 51, and the deflected and scanned laser light is deflected by the mirrors 49 and 50 so that the photosensitive drum 13 is driven. It is a structure to irradiate. Such a laser unit 12 is provided on the main body case 52.

The fixing device 47 is composed of a heating roller 46 and a pressure roller 45 provided on the main body case 52.

A process unit 11 including a charging device 54, an exposing device 60 and a developing device 57 and a laser unit 12
Thus, a toner image is formed on the photosensitive drum 13 of the photosensitive member by using a toner.

The sheets in the sheet feeding tray 15 separated by the sheet feeding roller 14 are conveyed by the conveying roller 16 to a conveying path 17.
The transfer roller 19 is conveyed above and electrically connected to the high-voltage power supply 18 to which a voltage is applied, so that an electric charge is applied.

Due to the potential difference generated between the photosensitive drum 13 and the photosensitive drum 13 by the electric charge applied to the paper, the photosensitive drum 13
The upper toner image is transferred onto the paper.

In FIGS. 1 and 3, the transfer roller 19 is
The power supply terminal 30, the spring 31, the bearing 35 made of a conductive material, the support shaft 22, the transfer roller shaft 21, and the transfer unit 20 are electrically connected to the high-voltage power supply 18.

The transfer roller 19 has a cylindrical transfer portion 20 made of a conductive sponge, and a cylindrical transfer roller shaft 21 made of a conductive material is integrally attached to the center of the transfer portion 20. ing. Further, support shafts 22 are provided at both ends of the transfer roller shaft 21 in the longitudinal direction.

The bearings 35 are attached to left and right side frames (not shown), respectively, and shaft support portions 36 each having a substantially cylindrical through hole for rotatably supporting the support shaft 22 of the transfer roller shaft 20 are respectively provided. Has been formed.

Further, as shown in FIG. 1, the transfer roller 1
The shaft supporting portion 36 on the 9 side is provided with an expanding shaft supporting portion 37 that is a conical expanding portion that expands toward the transfer roller 19 side. Further, the support shaft 22 of the transfer roller 19 which is rotatably supported by the shaft support 36 is also provided with an expanding support shaft 23 which is a conical expanding part which expands toward the transfer roller side. ing. In addition, a spacer 40 arranged between the bearing 35 and the transfer roller shaft 21 is inserted into the support shaft 22, and the toner 9 scattered in the image forming apparatus during operation is supported by the support shaft 22 and the shaft support portion. It is prevented from entering the gap formed with 36.

As shown in FIGS. 2A and 2B, the expanding support shaft 23 and the expanding shaft supporting portion 37 formed on the supporting shaft 22 and the shaft supporting portion 36, respectively, are at least directed toward the inside of the apparatus. Any shape may be used as long as it expands.

Next, the operation of the above embodiment will be described.

In the above structure, the electrostatic latent image formed on the photosensitive drum 13 by the exposing device 60 is applied to the developing device 57.
Then, the toner is attached and a toner image is formed on the photosensitive drum 13. The toner image formed on the photosensitive drum 13 is
It is sent to the transfer roller 19. This transfer roller 19 is electrically connected to a high voltage power source 18 of, for example, about -600 V, and charges are applied to the sheet conveyed on the conveying path 17 by the transfer roller 19 to which a voltage is applied by the high voltage power source 18. To be By the electric charge applied to the paper, the photosensitive drum 13
The toner image formed on the photosensitive drum 13 is transferred onto the paper due to the potential difference generated between the toner image and the toner image.

When the toner is attached to the electrostatic latent image formed on the photosensitive drum 13 by the developing device 57, and when the toner image on the photosensitive drum 13 is transferred onto the sheet by the transfer roller 19. , Toner 9 is scattered in the image forming apparatus. The scattered toner 9 is transferred to the transfer roller 19 and the bearing 3
The support shaft 2 is provided by a spacer 40 arranged between the support shaft 2 and the spacer 40.
2 does not enter the gap formed between the shaft support portion 36 and the shaft support portion 36. However, the toner 9 may enter the gap formed between the support shaft 22 and the shaft support portion 36, although the amount is very small.

However, the support shaft 22 and the shaft support portion 36 provided at both ends of the transfer roller 19 respectively expand the support shaft 23 and the support shaft portion 37 which expand toward the inside of the apparatus.
Is provided.

The gap formed between the expansion support shaft 23 and the expansion shaft support portion 37 expands toward the inside of the apparatus, and the lower half of the gap is inclined downward. Therefore, the toner 9 entering the gap formed between the expansion support shaft 23 and the expansion shaft support portion 37 moves in the rotation direction of the transfer roller 19 as the transfer roller 19 rotates. At the same time, the expanding shaft support 37, which expands toward the inside of the apparatus, moves along the downward slope and is discharged into the image forming apparatus.

Therefore, the electrical contact failure is prevented and the print failure due to the transfer failure is prevented.

Since the support shaft 22 and the shaft support portion 36 are provided with the expanding portions 23 and 37 that expand toward the inside of the apparatus, the contact area between the support shaft 22 and the shaft support portion 36 is expanded, and electrical connection is achieved. Will be more certain.

The arrangement relationship between the transfer roller and the photosensitive drum of the image forming apparatus is such that the transfer roller is arranged on the lower side of the photosensitive drum, or as described in the embodiment. There are things that are placed on top of. In the embodiment, since the process unit and the photosensitive drum, which are devices that generate toner that scatters inside the device, are located below the transfer roller, they are located between the support shaft of the transfer roller and the shaft support. The chance that the toner enters the formed gap is reduced.

[0034]

As described above in detail, according to the present invention, the toner that has entered the gap between the support shaft of the transfer roller of the image forming apparatus and the shaft supporting portion of the bearing expands toward the inside of the apparatus. Since the expanding portions that open are provided on the support shaft and the shaft supporting portion, respectively, as the transfer roller rotates, the toner moves along the downward inclination of the shaft supporting portion and is discharged into the image forming apparatus. Electrical contact failure is prevented, and printing failure due to transfer failure is prevented.

Further, the contact area between the support shaft of the transfer roller and the shaft support portion is enlarged, and the electrical connection is made more reliable.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a transfer roller of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a transfer roller of an image forming apparatus according to another embodiment.
FIG. 10A is a cross-sectional view showing another embodiment, showing the configuration of LA. (B) is sectional drawing which shows other embodiment.

FIG. 3 is a perspective view showing a configuration of a transfer roller of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a sectional view showing a general image forming apparatus.

FIG. 5 is a cross-sectional view showing the structure of a transfer roller of an image forming apparatus according to a conventional technique.

[Explanation of symbols]

 19 ... Transfer roller, 22 ... Support shaft, 23 ... Expansion support shaft (expansion part), 23a ... Expansion support shaft (expansion part), 23b ... Expansion support shaft (expansion part), 36 ... Shaft support part, 37 ... Expansion shaft support part (expansion part), 37a ... Expansion shaft support part (expansion part), 37b ... Expansion shaft support part (expansion part).

Claims (1)

[Claims] 1. A transfer roller disposed around a photosensitive member, support shafts formed at both ends of the transfer roller in a longitudinal direction, and shaft supporting portions rotatably supporting the support shafts. In the image forming apparatus including a bearing, the support shaft and the shaft support portion on the transfer roller side are each provided with an expanding portion for expanding toward the transfer roller side. apparatus.