JPH103246A - Image forming unit for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly carry transfer paper at the base of the image forming unit of an image forming device housing a photoreceptor, etc., in an integrated case. SOLUTION: Plural ribs 95 constituting a carrying guide for the transfer paper P are formed on the base of the case 17 of the image forming unit. The rib 95 is integrally molded with the case 17 and the projecting height from the base part of the case 17 is set so that a part just adjacent to a pair of resist rollers 24 at the time of attaching the case 17 in an image forming device main body may be the highest and the height reducing degree may be made small on a side near to the photoreceptor 18 by reducing the height to draw a large arc from a part just after passing the highest part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming unit of an image forming apparatus, and more particularly to an image forming unit having improved transferability of a transfer sheet to a transfer section.

[0002]

2. Description of the Related Art In recent years, image forming apparatuses such as copiers and facsimile machines have been miniaturized. However, in order to achieve the demand for miniaturization, a photoconductor, a developing device, An image forming unit is often configured by housing a charging device or the like in an integrated case to contribute to downsizing of the entire image forming apparatus. With such a configuration, an image forming system photoconductor, a developing unit,
The life of each component such as the cleaning blade, the charging roller, and the toner recycle unit can be made the same, which makes it more economical. Also, instead of replacing components at different times, replace one unit at a time. Only has to be done, and the handling is easy.

However, even in an image forming apparatus using such an image forming unit, transfer of transfer paper fed from a paper feeder and sent to a transfer section between a photosensitive member and a transfer roller by a pair of registration rollers is carried. As the guide, two guide plates made of sheet metal or the like formed separately from the image forming unit are used.
That is, two guide plates are arranged between the registration roller pair and the transfer unit with an appropriate gap therebetween, and the transfer paper is guided between the guide plates. Of course, the use of such a separate member naturally causes problems such as an increase in parts, an increase in cost, an increase in the number of manufacturing steps, and a troublesome assembling operation.

Further, in the conventional guide plate, since it is necessary to install the guide plate relatively upstream of the transfer portion in the transport direction, the rear end of the transfer sheet passing through the guide plate may jump due to the paper stiffness. . Even if the vibration or movement generated on the transfer paper by such a jump is slight, the photosensitive member 18
The transfer of an image from a printer may cause an abnormality, and a solution to this problem has been desired.

Furthermore, the conventional guide plate comes into sliding contact with the transfer paper in a relatively large area, and therefore has a contact resistance, which may cause frictional charging and abnormal images, which can be solved. Was desired.

Furthermore, resource conservation has become an important issue due to the recent increase in environmental protection consciousness. Even in an image forming apparatus, an image forming unit and other components are designed and manufactured so that they can be reused as much as possible. It is becoming.
However, although it is not impossible to recycle the guide plate formed as a separate part as described above, it takes time and trouble to remove and re-attach the guide plate, and therefore, a solution has been desired.

Accordingly, the present invention has been made in view of the above conventional problems,
An image forming apparatus that has a transfer paper guide structure that can smoothly guide the transfer paper, has low contact resistance, and can be easily reused without increasing the number of parts or increasing the cost. It is an object to provide an image unit.

[0008]

According to a first aspect of the present invention, there is provided an image forming unit for an image forming apparatus, comprising: In the image forming unit of the image forming apparatus to be accommodated in the image forming apparatus, the transfer paper transport guide for the transfer paper transport guide is provided on the bottom portion of the case located on the opposite side of the registration roller in the transfer paper transport direction upstream when mounted in the image forming apparatus main body. A rib is formed so as to protrude from the bottom surface of the case so that the height of the rib from the vicinity of the pair of registration rollers decreases smoothly toward the downstream side in the transfer paper transport direction. And

According to a second aspect of the present invention, the degree of reduction of the height of the rib protruding from the bottom of the case is increased at a portion immediately after passing the vicinity of the pair of registration rollers, and the transfer is more than at the portion. The reduction degree is reduced toward the downstream side in the paper transport direction.

According to a third aspect of the present invention, the height of the rib from the bottom of the case is reduced on the side of the bottom where the transfer paper enters the photosensitive member. A plurality of auxiliary ribs having a protrusion height equal to or less than the reduced protrusion height are formed between the ribs.

According to a fourth aspect of the present invention, the rib is formed integrally with the case.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming unit of an image forming apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing an appearance of an embodiment of an image forming unit of an image forming apparatus according to the present invention, and FIG. 2 shows an arrangement of an image forming unit, a transfer / separation device, a fixing device and the like according to the embodiment of the present invention. FIG. 3 is a perspective view showing the bottom structure of the case around the photoreceptor of the image forming unit of FIG. 1, and FIG. 4 is a sectional view showing the main part in an enlarged manner.

In these figures, reference numeral 10 denotes an image forming unit, 11 denotes a transfer / separation device, and 12 denotes a fixing device. The image forming unit 10 is formed in a cartridge shape and is not shown in the drawing. It is removable.
Further, the transfer / separation device 11 includes a transfer roller 13 and is rotatable in a vertical direction in FIG.
The fixing device 12 includes a pressure roller 15 and a heating roller 16.

The illustrated image forming unit 10 includes a resin photoreceptor surrounding case (hereinafter simply referred to as a case) 17.
The photoreceptor 18, a charging roller 19 constituting a charging device, a developing device 20, a cleaning device 21, a toner recycling belt 22 for feeding residual toner collected by the cleaning device 21 to the developing device 11, and a toner conveying screw 4
2. An agent stirring member 43 and the like are provided. In the figure, reference numeral 37 denotes an upper cover which is attached so as to cover the case 17;
8 and the charging roller 19 are prevented from contacting a person.

An image forming operation using the image forming unit configured as described above will be briefly described. First, with the image forming apparatus main body mounted at a predetermined position, the photosensitive member 18 is rotatable in the direction indicated by the arrow in FIG. 2 by a drive source (not shown). The surface is neutralized by irradiating static elimination light from a static elimination lamp (not shown), and the surface potential is averaged to a reference potential of, for example, 0 to -150V. Next, a high voltage is applied to the charging roller 19 which is in contact with the surface of the photoreceptor 18 to charge the photoreceptor 18, and the surface potential is set to, for example, about -1100V. Then, the charged potential surface is exposed, and the surface potential to form an image is, for example, 0 to 0.
A latent image portion of -290 V is formed.

When the latent image portion is moved to the position of the developing sleeve 23 of the developing device 20 by the rotation of the photosensitive member 18, the latent image portion is held on the surface of the developing sleeve 23 in which a bias of, for example, about -800 V is applied. The latent toner adheres, and the latent image portion is developed to become a toner image (visible image).

On the other hand, the transfer paper P fed from a paper feed unit (not shown) is moved by the registration roller pair 24 so that the front end of the transfer paper P and the front end of the toner image on the photoreceptor 18 coincide at the position of the transfer roller 13. The timing is adjusted, and the toner image on the photoconductor 18 is transferred to the transfer paper P by the transfer roller 13. The transfer paper P is conveyed between the pressure roller 15 and the heating roller 16 of the fixing device 12, where the transferred toner is fused to the transfer paper P by heat and pressure, and is transferred to a discharge tray (not shown) outside the apparatus. Discharge.

The residual toner remaining on the photoreceptor 18 after the image transfer is scraped off by a cleaning blade 25 of a cleaning device 21. Move to The residual toner collected by the cleaning device 21 is transferred to the developing device 20 by the toner recycling belt 22.
Is transported to the developer agitating section 26, and is collected.
And the toner is recycled by supplying the toner to the developing sleeve 23 again. In the figure, 41 is the cleaning blade 2
5 holder.

The image forming unit 10 shown in FIG. 1 includes a portion accommodating the agent stirring member 43 which is located immediately above the registration roller pair 24 when the image forming unit 10 is mounted on an image forming apparatus main body (not shown) and the photosensitive member 18. A plurality of ribs 95... Constituting a transfer guide of the transfer paper P are formed on the bottom surface of the case 17 between the portion exposed to the outside. These ribs 95 are formed integrally with the case 17 and
7 is projected from the bottom of the registration roller pair 24
The portion immediately adjacent to the photoconductor 18 is made the highest, and is formed so as to be smoothly lowered toward the photoreceptor 18 downstream of the transfer paper transport direction.

More specifically, the height of the rib 95 decreases relatively rapidly so as to draw a large arc immediately after passing the highest part near the registration roller pair 24, and the rib 95 is close to the photosensitive member 18. On the other side, the degree of height reduction is reduced. Further, the top edge of each rib 95 is thin and rounded as shown in the figure, so that the contact resistance with the transfer paper P in sliding contact is extremely small. The shape of the ribs employed in the present invention is not limited to the illustrated embodiment, and various shapes can be used. In the illustrated embodiment, FIG.
As shown in the figure, a large number of auxiliary ribs 96 having a short length are provided on the photosensitive member 18 side between the ribs 95. The rib 96 is for preventing the transfer paper P from being caught when the paper is curled and sent.

For this reason, the transfer paper P conveyed by the pair of registration rollers 24 is guided with its leading end slidably in contact with the top edge near the minimum protruding height portion of the rib 95 close to the photoreceptor 18, so that the transfer paper P is brought into contact with the photoreceptor 18. The paper is fed between the transfer rollers 13, and the contact resistance at this time is small, and the paper is smoothly guided. Generally, the transfer paper P bends toward the bottom side of the case 17 when the leading end enters the nip portion between the photoreceptor 18 and the transfer roller 13, and tends to jump up after the rear end passes through the registration roller pair 24. , Rib 9
Such a behavior is suppressed and smoothly guided by the top edge which becomes lower in an arc shape continuing from the highest part of No. 5.

[0022]

As described above, the image forming unit of the image forming apparatus according to the present invention is provided on the bottom of the case of the image forming unit smoothly from the vicinity of the pair of registration rollers toward the downstream side in the transfer paper transport direction. The ribs for the transfer paper transport guide, which are extremely low, protrude, so that it is possible to guide the transfer paper while preventing the trailing edge of the transfer paper from jumping up without causing an increase in the number of parts and cost. There is.

In the image forming unit of the image forming apparatus according to the second aspect, the degree of decrease in the height of protrusion of the rib from the bottom surface of the case is increased at a portion immediately after passing the vicinity of the pair of registration rollers, and the transfer paper is then transferred therefrom. Since the degree of decrease becomes smaller toward the downstream side in the transport direction, in addition to the above-mentioned common effect, the effect that the rear end of the transfer paper can be smoothly guided and prevented from jumping up can be guided. is there.

According to a third aspect of the present invention, there is provided an image forming unit for an image forming apparatus, wherein the height of the rib projecting from the bottom of the case is reduced on the side of the bottom where the transfer paper enters the photosensitive member. Since a plurality of auxiliary ribs having a projecting height equal to or less than the reduced projecting height are formed between them, in addition to the above-mentioned common effect, it becomes possible to guide the transfer sheet while preventing the transfer sheet from being curled and fed. This has the effect.

In the image forming unit of the image forming apparatus according to the fourth aspect, since the rib is formed integrally with the case, in addition to the above-mentioned common effects, it is not necessary to use a separate member for the guide of the transfer sheet as in the prior art. For this reason, if the case can be reused, the transfer paper conveyance guide can be reused, and there is an effect that efficient recycling becomes possible.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an appearance of an embodiment of an image forming unit of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view illustrating an arrangement of an image forming unit, a transfer / separation device, a fixing device, and the like according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a bottom structure of a case around a photoreceptor of the image forming unit of FIG. 1;

FIG. 4 is an enlarged cross-sectional view illustrating a main part of a bottom structure of a case around a photosensitive member of the image forming unit in FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 image forming unit 11 transfer / separation device 12 fixing device 13 transfer roller 14 rotation fulcrum 15 pressure roller 16 heating roller 17 photosensitive member surrounding case 18 photosensitive member 19 charging roller 20 developing device 21 cleaning device 22 toner recycling belt 23 developing sleeve 24 Registration roller pair 25 Cleaning blade 26 Developer stirring section 37 Upper cover 41 Cleaning blade holder 42 Toner conveying screw 43 Agent stirring member 95 Rib 96 Rib P Transfer paper

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigeru Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kenzo Tatsumi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh Company (72) Inventor Takeo Suda 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Hiroshi Yoshinaga 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company ( 72) Inventor Ken Amamiya 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Mayumi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd.

Claims (4)

[Claims] 1. An image forming unit for an image forming apparatus in which a photoconductor, a developing device, a charging device, and the like are housed in an integrated case. A transfer paper transport guide rib is protruded from the bottom of the case located on the roller pair side, and the height of the rib protruding from the bottom of the case is adjusted from the vicinity of the registration roller pair to the transfer paper transport direction. An image forming unit for an image forming apparatus, wherein the image forming unit is formed so as to be smoothly lowered toward a downstream side. 2. The degree of reduction in the height of protrusion of the rib from the bottom of the case is increased at a portion immediately after passing the vicinity of the pair of registration rollers, and the rib is located further downstream in the transfer paper transport direction than the portion. 2. The image forming unit according to claim 1, wherein the degree of reduction is reduced. 3. A projection on the side of the bottom of the transfer paper at which the transfer paper enters the photosensitive member, where the height of the rib from the bottom of the case is reduced. 3. An image forming unit for an image forming apparatus according to claim 1, wherein a plurality of auxiliary ribs having a height are formed between said ribs. 4. An image forming unit according to claim 1, wherein said rib is formed integrally with said case.