JP2001350321A - Image forming device and image carrier unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electrification performance from lowering because a gap control member making an electrifying member non-contact with an image carrier is worn. SOLUTION: An electrifying roller 14 is brought into contact with the surface of a photoreceptor drum 5 through a tape members 18 and 18 brought into contact with the coating part 61 of the drum 5, and a gap G is formed between the part of the electrification effective width Wac of the roller 14 of an electrifying device 4 and the surface of the drum 5. Thus, the wear or the damage of the member 18 is made smaller than in the case the member 18 is brought into contact with a non-coating part 62 formed of harder material than the coating part 61. Therefore, even though the thickness of the member 18 is set to <=100 μm, the member 18 is not worn drastically, so that the part of the electrification effective width Wac of the roller 14 is prevented from coming into contact with the drum 5.

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 provided with an image carrier having a photosensitive layer and a charging means having a charging member for charging the image carrier, and an image mounted on the image forming apparatus. It relates to a carrier unit.

[0002]

2. Description of the Related Art Heretofore, a charging member having an effective width of a charging member has been arranged close to the surface of a photosensitive member as an image carrier, and a voltage has been applied between the charging member and the photosensitive member to apply a voltage to the photosensitive member. There is a non-contact type charging device that charges the surface of the device. In such a charging device, there is an advantage that the charging member is less likely to be stained because the portion of the effective charging width of the charging member does not contact the surface of the photoconductor.

In such a non-contact type charging device, for example, a convex portion is formed by attaching tape members to both ends of a roller portion of a charging roller which is a charging member, thereby removing the both ends of the charging roller. Is made non-contact with the surface of the photoreceptor as the image carrier. FIG. 14 shows an example of the charging roller. The charging roller 114 is provided with an elastic portion 117 having conductivity, for example, on the outer periphery of a cored bar 116 made of stainless steel.
Resin tape members 118, 118 are wound around both ends of the base member 17 in the circumferential direction and fixed integrally.

[0004] Both ends of the cored bar 116 are pressed by the pressing springs 119, 119 to the photosensitive drum 105 side through sliding bearings 130, 130 with a predetermined pressing force. As a result, the charging roller 114 has the tape members 118 on both sides in contact with the surface of the photosensitive drum 105, and the charging effective width Wac of the elastic portion 117 is not in contact with the surface of the photosensitive drum 105. Contact (a gap G corresponding to the thickness of the tape member 118 is formed).

[0005]

However, a tape member having a predetermined thickness is integrally fixed to both ends of the charging roller as described above, and the tape member is brought into contact with the photosensitive drum to thereby charge the charging member. In a non-contact type charging device that forms a predetermined gap in the portion of the effective charging width between the roller and the surface of the photosensitive drum,
In some cases, wear of the tape member became a problem.

That is, the gap G shown in FIG.
If the width is too wide, a predetermined charging performance cannot be obtained. Therefore, the gap G is, for example, about 100 μm.
Or it needs to be less. Therefore, the thickness of the tape member is extremely small, about 100 μm or less. However, since the tape member keeps rotating while the outer peripheral surface is in contact with the surface of the photosensitive drum,
It is inevitable that the outer peripheral surface wears over time.

If the tape member is worn out at an early stage, the charging roller comes into contact with the surface of the photosensitive drum in a portion of the effective charging width (the gap is zero). In such a case, residual toner on the photosensitive drum is transferred to the portion of the effective charging width of the charging roller, so that the contamination causes poor charging.

The present invention has been made in view of the above-mentioned problems, and maintains good charging performance for a long period of time by preventing a gap management member such as a tape member from being worn easily. An object is to obtain high image quality.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image having a coating portion for forming a photosensitive layer and non-coating portions formed on both sides of the coating portion with a material harder than the coating portion. In an image forming apparatus including a carrier and a charging unit having a charging member for charging a coating portion of the image carrier, a gap in which the charging member is brought into contact with a non-charging area of the coating portion of the image carrier. The charging member is brought into contact with the surface of the image carrier via the management member, and a predetermined gap is formed between the charging member in the effective charging width portion of the charging means and the surface of the image carrier.

In the above-mentioned image forming apparatus, a cleaning means for cleaning with a predetermined cleaning width by slidingly contacting a coating portion of the image carrier is provided, and the gap management member is positioned within the cleaning width of the cleaning means. It is good to Then, the cleaning width is preferably set to extend outside the outer edge of the gap management member. Further, the cleaning width of the cleaning means may be located inside the gap management member.

In any of the above image forming apparatuses, a cleaning member oscillating mechanism for oscillating the cleaning member of the cleaning means in a direction perpendicular to the direction in which the cleaning member slides on the image carrier is provided. The width of the cleaning swing area of the cleaning member that is swung by the mechanism may be the cleaning width.

Preferably, the cleaning means is a means for sliding the cleaning blade into contact with a coating portion of the image carrier to clean the coating portion. In any one of the above image forming apparatuses, a transfer member for transferring a visible image formed on the surface of the image carrier to a transfer material is provided, and the effective transfer width of the transfer member is smaller than the effective charge width of the charging unit. Good to do. In any one of the image forming apparatuses described above, the image forming apparatus further includes a developing device that develops a latent image on the image carrier with a developer to make the visible image visible, and a developing width of the developing device is larger than an effective charging width of the charging unit. It is good to make it narrow.

In the above-described image forming apparatus provided with a developing device for developing the latent image on the image carrier with a developer to form a visible image, the developing width of the developing device may be smaller than the effective transfer width. The image forming apparatus is more effective when a two-component developer using a toner and a carrier is used as the developer.

In the above image forming apparatus, it is preferable that the cleaning width is wider than the effective charging width. Further, a cleaning member oscillating mechanism for oscillating the cleaning member of the cleaning means in a direction orthogonal to the sliding direction of the cleaning member with respect to the image carrier is provided, and both sides of the cleaning member oscillated by the cleaning member oscillating mechanism. It is preferable that the image forming apparatus is configured such that the positions of the movement limits are outside the effective charging width.

[0015] The charging member is a charging roller having elastic portions formed at portions other than both ends of the outer peripheral surface of the metal shaft, and the gap management member is a pair of tape members fixed to both ends of the elastic portion, respectively. It is preferable that the width between the insides of the pair of tape members be the effective charging width. The tape member may have a thickness of 100 μm or less.

The pair of tape members are wound around the both ends of the elastic portion in the circumferential direction, so that the two ends in the circumferential direction do not overlap with each other, and the tape members in the axial direction of the roller at all positions around the circumference. Are preferably fixed so that there are no parts that do not exist.
Further, it is preferable that both ends of the pair of tape members are cut obliquely so that the cut edges face each other, and a gap is formed between the cut ends. Further, it is preferable that the angle of inclination of the cut lines of the obliquely cut portions at both ends of the pair of tape members with respect to the side edge of the tape member is approximately 45 degrees.

The charging roller is arranged such that when a voltage is applied between the metal shaft and the image bearing member, a position where no leakage occurs from both ends of the metal shaft to the non-coated portion of the image bearing member. It is good to arrange both ends apart from the non-coating part. Further, the charging member may be a charging roller having elastic portions formed at portions other than both ends of the outer peripheral surface of the metal shaft, and the gap management member may be rollers attached to both ends of the metal shaft of the charging roller. Further, an image carrier having a photosensitive layer and a charging unit having a charging member for charging the image carrier are provided, and the image is formed via a gap management member in which the charging member is brought into contact with a non-charged area of the image carrier. In an image forming apparatus in which a predetermined gap is formed between the charging member and the surface of the image carrier, a predetermined cleaning is performed by slidingly contacting the surface of the image carrier. It is preferable to provide a cleaning means for cleaning by the width, and to make the gap management member be positioned within the cleaning width of the cleaning means. Still further, the present invention provides an image carrier unit in which the image carrier and the charging member are integrally provided as an image carrier unit to be mounted on any one of the image forming apparatuses.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a charging roller and a photosensitive drum provided in an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged view showing one end of the charging roller. FIG. 3 is an overall configuration diagram showing a small color printer as the image forming apparatus.

The color small printer as the image forming apparatus shown in FIG. 3 is a four-drum full-color electrophotographic image forming apparatus, and a photoconductor as four image carrier units is provided in the apparatus main body 1. Units 2A, 2B, 2C and 2
D are detachably attached to the apparatus main body 1. In this small-sized printer, a transfer belt 3 is mounted at a substantially center in the apparatus main body 1 so as to be rotatable between a plurality of rollers in a direction indicated by an arrow A.

Then, the photosensitive drums 5 provided in the four photosensitive units 2A, 2B, 2C, and 2D are brought into contact with the upper surface of the transfer belt 3 in FIG. Units 2A to 2D are provided respectively. The developing device 1 uses a different toner color for each of the photoreceptor units 2A to 2D.
0A to 10D are provided.

A writing unit 6 is provided above the photosensitive units 2A to 2D, and a duplex unit 7 is provided below the photosensitive units 2A to 2D. Further, this small printer is equipped with a reversing unit 8 for reversing and discharging the transfer paper P after image formation and conveying it to the duplex unit 7 on the left side of the apparatus main body 1 in FIG.

Between the transfer belt 3 and the reversing unit 8, there is provided a fixing device 9 for fixing the image of the transfer paper on which the image has been transferred. On the downstream side of the fixing device 9 in the transfer paper transport direction, a reverse transport path 20 is formed by branching, and the transfer paper P transported there is allowed to be discharged onto a paper discharge tray 26 by a paper discharge roller pair 25. .

In the lower part of the apparatus main body 1, a paper feed cassette 1 capable of storing transfer papers P having different sizes in two upper and lower stages is provided.
1 and 12 are provided respectively. Further, a manual tray 13 is provided on the right side of the apparatus main body 1 so as to be openable and closable in the direction of arrow B, and the manual tray 13 is opened so that manual paper can be fed therefrom.

The photoreceptor units 2A to 2D are units having the same configuration. The photoreceptor unit 2A forms an image corresponding to yellow, the photoreceptor unit 2B forms an image corresponding to magenta, The photoconductor unit 2C forms an image corresponding to cyan, and the photoconductor unit 2D
Forms an image corresponding to the black color. Then, they are arranged at intervals in the transport direction of the transfer paper.

As shown in FIG. 4, each of the photoreceptor units 2A to 2D has a charging roller 14 of a charging device 4 serving as a charging unit, and the surface thereof is charged by the charging roller 14. The photosensitive drum 5 which is an OPC drum type image carrier to be formed, and a cleaning blade 47 and a brush roller 15 which constitute a cleaning device (cleaning means) for cleaning the surface of the photosensitive drum 5 are integrated into an integrated unit. Make up,
This is detachable from the apparatus main body 1 shown in FIG.

As shown in FIG. 1, the charging device 4 is arranged such that the effective charging width Wac of the charging roller 14 serving as a charging member is brought closer to the charged surface (surface) of the photosensitive drum 5 in a configuration described later. Then, a voltage is applied between the charging roller 14 and the photosensitive drum 5 to charge the charged surface of the photosensitive drum 5.

The charging roller 14 of the charging device 4 is, for example,
SUM-Ni plating (Steel surface is nickel-plated
Both ends of the outer peripheral surface of the cored bar 16 which is a metal shaft formed by
Except for parts made of epichlorohydrin rubber
And the volume resistivity is 1 × 10 ³~ 1 × 10⁸Ω · cm
The conductive rubber roller portion 17 as an elastic portion was formed.
Things.

At both ends of the conductive rubber roller portion 17, an adhesive sheet having one surface made of, for example, polyester or polyethylene terephthalate is formed on an adhesive surface, and tape members 18, 1 serving as gap management members are provided.
8 is wound in the circumferential direction with the adhesive side facing down.

Then, each of the tape members 18, 1 on both sides thereof
8 as shown in FIG. 2 showing the tape member 18 on one side,
Edges 18a and 18b on both sides which are both ends in the circumferential direction, respectively.
The adhesive surface side is fixed by sticking so that there is no portion where the tape member 18 does not exist in the axial direction of the roller indicated by the arrow E at all positions around the circumference without overlapping each other.

Therefore, as shown in FIG.
8 are cut diagonally, edges 18a and 18b of the cut face are opposed to each other, and a gap S is formed between the cut edges 18a and 18b at both ends. Further, an edge 1 serving as a cut line of a diagonally cut portion of each of both ends of the pair of tape members 18, 18.
The inclination angles θ ₁ and θ ₂ of the tapes 8a and 18b with respect to the side edges of the tape member 18 are both set to approximately 45 degrees.

As described above, when the inclination angles θ ₁ and θ ₂ of the cut lines of the tape member 18 are set to approximately 45 degrees, the ends of both ends of the tape member 18 in the winding direction are set to the elastic portions 1.
7 can be hardly peeled off. Further, the contact width between the tape member 18 and the photosensitive drum at the joint portion (the portion where the gap S is formed) can be increased, so that both ends of the tape member 18 can be made sharper than when the inclination angles θ ₁ and θ ₂ are acute. The sticking force of the tip portion to the elastic portion 17 increases. Therefore, it is possible to prevent the end portions at both ends of the tape member 18 from peeling off.

As shown in FIG. 4, the charging roller 14 is brought into contact between the charging roller 14 and the photosensitive drum 5 by bringing the tape members 18 at both ends into contact with the photosensitive drum 5. A charging device 4 that charges the surface of the photoconductor drum 5 by applying a voltage from a power supply that does not use the power supply is configured.

As shown in FIG. 1, the charging roller 14 has both ends of the metal core 16 sliding on the photosensitive drum 5 via sliding bearings 30, 30 by pressure springs 19, 19 with a predetermined pressing force. Pressurized. The charging roller 14
Alternatively, the tape members 18 at both ends may be brought into contact with the photosensitive drum 5 by its own weight without using the pressure spring 19.

A driving gear 40 is fixed to one end of the core 16 on the right side in FIG. 1, and a driving force from a motor (not shown) is transmitted to the driving gear 40 so that the charging roller 14 is connected to the same line as the photosensitive drum 5. It rotates at high speed. Charging roller 14
The voltage is applied to the core 16 by, for example, DC-7.
00V is applied under constant voltage control, and AC voltage is applied under constant current control.

In the charging roller 14, for example, the outer diameter of the cored bar 16 is formed to be 9 mm, and the conductive rubber roller portion 17 is formed as a rubber layer made of the above-mentioned epichlorohydrin rubber having a wall pressure of 1.5 mm. In this embodiment, the tape member 18 wound around both ends of the conductive rubber roller portion 17 has a tape width of, for example, 8 mm and a thickness of 25 to 125 μm. The thickness of the tape member 18 is 1
If the thickness is not more than 00 μm, more stable charging performance can be obtained. Further, the conductive rubber roller portion 17 has a rubber hardness of about 77 degrees in the old JIS-A and a test piece hardness of the rubber itself of 50 degrees or more.

The photosensitive drum 5 is rotationally driven in a direction indicated by an arrow C in FIG. 4 by a motor which is rotationally driven through a drum driving timing belt, a drum driving pulley (both not shown) and the like. Each of the photoreceptor units 2A to 2D provided with the photoreceptor drum 5 has its tip slidably contacted with a later-described coating portion 61 on the surface of the photoreceptor drum 5, and the coating portion 61
A cleaning blade 47 is provided for cleaning by scraping off residual toner and the like adhering to the toner. The toner scraped off by the cleaning blade 47 is moved to the toner conveying auger 48 side by the brush roller 15, and the toner is conveyed. The waste toner collected by rotating the auger 48 is transported to a predetermined waste toner storage unit.

The photosensitive units 2A to 2D are
Also on the surface of the conductive rubber roller portion 17 of the charging roller 14,
For example, when a charging roller cleaner 49 made of a sponge is brought into contact with the conductive rubber roller 17, even if toner, dust, or the like floating in the apparatus adheres to the surface of the conductive rubber roller 17, it can be cleaned.

The photoconductor units 2A to 2D are provided with a positioning main reference portion 51 as a reference for attaching and detaching the photoconductor units to and from the apparatus main body 1 (see FIG. 3).
The near side positioning reference part 52 and the back side positioning reference part 5
When the photoconductor units 2A to 2D are mounted on the apparatus main body 1, the photoconductor units 2A to 2D can be reliably positioned at predetermined mounting positions by their reference portions. Like that.

Each of the photosensitive drums 5 of the photosensitive units 2A to 2D rotates in the direction of arrow C as described above, and their linear velocities are monochrome speed priority mode, monochrome image quality priority mode, and color speed priority. 185mm / sec, 125mm / sec depending on several modes such as mode, color image quality priority mode, thick paper / OHP passing mode
c, it can be adjusted in three stages of 62.5 mm / sec. In addition, this photoconductor unit
The brush roller 15 may be removed from the configuration, and the charging roller 14 and the photosensitive drum 5 may be configured as an integrated unit.

The developing devices 10A to 10D shown in FIG.
The configurations are all the same, and they differ only in the color of the toner used. The developing device 10A uses a yellow toner, the developing device 10B uses a magenta toner, the developing device 10C uses a cyan toner, and the developing device 10D uses a black toner. .

The writing unit 6 shown in FIG. 5 is a writing unit of a one-polygon motor having two six-sided rotating polygon mirrors 22a and 22b of one laser diode (LD) type, one color beam and two monochrome beams. The writing unit 6 includes yellow scanning light and magenta scanning light and cyan scanning light by rotating polygon mirrors 22 a and 22 b emitted from a laser diode (not shown) serving as a light source and rotated by a polygon motor 21. And the scanning light for black are reflected right and left separately.

The scanning light for yellow and the scanning light for magenta pass through the two-layer fθ lens 23, respectively, and the scanning light for yellow is reflected by the mirror 27 to form a long WTL 24.
Through the mirror unit 28 via the mirrors 28 and 29
A is irradiated on the photosensitive drum 5 of A. The scanning light for magenta is reflected by the mirror 31, passes through the long WTL 32, and passes through the mirrors 33 and 34 to the photosensitive unit 2 </ b> B.
Is irradiated on the photosensitive drum 5.

Further, the scanning light for cyan and the scanning light for black pass through the two-layer fθ lens 35, respectively, and the scanning light for cyan is reflected by the mirror 36 to form a long WTL 37.
Through the photoreceptor unit 2 via mirrors 38 and 39
C is irradiated onto the photosensitive drum 5. The scanning light for black is reflected by the mirror 41, passes through the long WTL 42, and passes through the mirrors 43 and 44 to the photosensitive unit 2D.
Is irradiated on the photosensitive drum 5.

The duplex unit 7 shown in FIG. 3 comprises a pair of transport guide plates 45a and 45b and a pair (four in this example) of transport rollers 46, and forms images on both sides of the transfer paper. In the double-sided image forming mode, the transfer paper P on which an image is formed on one side and conveyed to the reversing conveyance path 54 of the reversing unit 8 and conveyed by switchback is received, and the photoconductor units 2A to 2D are provided. Is re-conveyed to the current image forming unit.

The reversing unit 8 is composed of a plurality of pairs of transport rollers and a plurality of pairs of transport guide plates. The reversing unit 8 reverses the transfer paper P when forming a double-sided image as described above, and forms a double-sided unit. 7 and discharges the transfer paper P after image formation to the outside of the apparatus in the same direction, or reverses the front and back to discharge the transfer paper P to the outside of the apparatus. Separating sheet feeding sections 55 and 56 for separating and feeding the transfer sheets P one by one are provided in the sheet feeding sections provided with the sheet feeding cassettes 11 and 12.
Are provided respectively.

This small printer employs a roller curvature separation system using the transfer belt 3.
Inside, are provided four transfer brushes 57 corresponding to the four photosensitive drums 5, respectively.

In this small printer, when an image forming operation is started, each photosensitive drum 5 rotates clockwise in FIG. Then, the surface of each photosensitive drum 5 is
When a voltage is applied between the photosensitive drum 5 and the charging roller 14 of each charging device, charging is performed uniformly. Then, the writing unit 6 irradiates the charged surface of the photosensitive drum 5 of the photosensitive unit 2A with a laser beam corresponding to a yellow image.

The writing unit 6 applies a laser beam corresponding to a cyan image on the charged surface of the photosensitive drum 5 of the photosensitive unit 2B, and a magenta laser beam on the charged surface of the photosensitive drum 5 of the photosensitive unit 2C. A laser beam corresponding to the color image is irradiated on the charged surface of the photoconductor drum 5 of the photoconductor unit 2D, and a laser beam corresponding to the black image is irradiated thereon, and a latent image corresponding to each color is formed thereon. Is done. Then, when the respective latent images reach the positions of the developing devices 10A, 10B, 10C and 10D by the rotation of the photosensitive drum 5, the latent images there are yellow, magenta,
The toner images are developed with cyan and black toners to form four color toner images.

On the other hand, the transfer paper P is fed from the selected paper feed tray in the paper feed cassette 11 or 12 by the separation paper feed unit 55 or 56, and is fed to the photosensitive unit 2A.
The registration roller pair 59 provided immediately before
At an accurate timing coincident with the toner image formed on each photoconductor drum 5, it is conveyed between the photoconductor drum 5 of the photoconductor unit 2 </ b> A and the transfer belt 3.

At this time, the transfer paper P is charged to a positive polarity by the paper suction roller 58 disposed near the entrance of the transfer belt 3, and is thereby electrostatically attracted to the surface of the transfer belt 3. . Then, while the transfer paper P is attracted to the transfer belt 3 and conveyed in the same direction by the rotation of the transfer belt 3 in the direction of arrow A, yellow, magenta, cyan, and cyan The black toner images are sequentially transferred, and when passing through the photoreceptor unit 2D, a full-color toner image of four colors is formed.

The transfer paper P is melted and fixed by applying heat and pressure to the transfer paper P in the fixing device 9, and thereafter passes through a paper discharge system according to a designated mode, and is discharged to the upper part of the apparatus main body. The sheet is inverted and discharged to the paper tray 26, or is straightly discharged from the fixing device 9 and passes through the inside of the reversing unit 8.

Alternatively, when the two-sided image forming mode is selected, the sheet is fed back to the reversing conveyance path 54 in the reversing unit 8 and is then switched back and conveyed to the two-sided unit 7, where it is fed again. In the image forming unit provided with the photoconductor units 2A to 2D, the image is discharged after an image is formed on the back surface. Thereafter, when an instruction to form two or more images is given, the above-described image forming process is repeated.

The small printer includes the photosensitive drum 5 as described with reference to FIG. 1. The photosensitive drum 5 has a coating section 61 for forming a photosensitive layer and coating sections on both sides thereof. Non-coated part 6 formed of a material harder than 61
2, 62, and the effective charging width W of the coating portion 61
The charging device 4 charges the ac portion. Then, the charging roller 14 of the charging device 4 is moved to the coating unit 6 of the photosensitive drum 5.
1, the surface of the photosensitive drum 5 is brought into contact with the surface of the photosensitive drum 5 via the tape members 18, 18 which are in contact with the non-charged area of the photosensitive drum 5. A predetermined gap G is formed between them.

Therefore, each of the tape members 18 is
The wear and damage of the tape member 18 can be reduced as compared with the case where the tape member 18 is in contact with the non-coated portion 62 made of a material harder than the material 1. Therefore, even if the tape member 18 has a thickness of 100 μm or less so that good charging performance can be obtained, the tape member 18 is hard to be worn.
The gap G between the photoconductor drum 4 and the surface of the photosensitive drum 5 can be maintained at a predetermined gap amount at which good charging performance can be obtained for a long period of time. Thereby, good image quality can be maintained over time.

FIG. 6 is a schematic diagram showing a relative comparison of the width relationship of each part constituting the image forming system of the small printer of FIG. Each part constituting the image forming system of the small printer shown in FIG. 3 has a width relationship as shown in FIG. 6 and a total width Wdo in the longitudinal direction of the photosensitive drum 5 and a coating portion 61 of the photosensitive drum 5. Coating width W
t, the uncoated width Wnt of the uncoated portion 62 of the photosensitive drum 5
, The effective charging width Wac of the charging device 4, the tape width Wta of the left and right tape members 18, 18, and the developing devices 10A to 10A.
Each developing width Wde of 10D, the effective transfer width Wte of the transfer device having the transfer belt 3, and the cleaning blade 47
(See also FIGS. 3 and 4).

That is, a pair of tape members 18, 18 (of a tape width Wta) is provided within the cleaning width Wc of the cleaning blade 47 that slides on the coating portion 61 on the surface of the photosensitive drum 5 to clean the coating portion 61. (Located at the position). Thereby,
The coating unit 61 of the photoconductor drum 5 includes the cleaning blade 4
Even if the area of the cleaning width Wc wears over time due to the sliding contact of the charging roller 7 (see FIG. 4), the pair of tape members 18 and 18 come into contact with the worn part, and the charging roller shown in FIG. The gap G between the portion of the effective charging width Wac of No. 14 and the surface of the photosensitive drum 5 can always be kept constant. Thereby, a good image can be obtained over time. In this embodiment, the width between the inner sides of the pair of tape members 18 is the effective charging width Wac (see FIG. 1 as necessary).

The transfer belt 3 is a transfer member that contacts a coating portion 61 of the photosensitive drum 5 to transfer a visible image formed on the surface of the photosensitive drum 5 to transfer paper (transfer material).
The effective transfer width Wte (see FIG. 3) is smaller than the effective charge width Wac of the charging device 4. As a result, the charging potential becomes unstable near the outer ends of both ends of the effective charging width Wac on the surface of the photosensitive drum 5, so that the developer is likely to adhere. However, the effective transferring width Wte is made smaller than the effective charging width Wac. Thereby, it is possible to prevent the developer (toner and carrier in the case of a two-component developer) attached to the vicinity of the outside of both ends of the effective charging width Wac from being transferred to the transfer belt 3.

Further, the developing width Wde of each of the developing devices 10A to 10D that develops the latent image on the photosensitive drum 5 with a developer to form a visible image is made smaller than the effective charging width Wac. Thereby, it is possible to prevent the developer from adhering to the vicinity of both ends of the effective charging width Wac on the photosensitive drum 5. Therefore, the developer enters between the tape member 18 and the surface of the photosensitive drum 5 described with reference to FIG. 1 to increase the gap G or to increase the effective charging width Wac.
Can be prevented from being adversely affected when the developer adheres to the vicinity of both ends.

The development width Wde is smaller than the effective transfer width Wte. As a result, the developer can be further prevented from adhering to the vicinity of both ends of the effective charging width Wac on the photosensitive drum 5. When the developer is a two-component developer using a toner and a carrier, the toner and the carrier are both charged effective width W on the photosensitive drum 5.
It can be prevented from adhering near both ends of ac.

Further, the cleaning width Wc is set wider than the effective charging width Wac. Thereby, even if the deposit such as the developer adheres to the portions located at both ends of the effective charging width Wac on the photosensitive drum 5, the portions can be cleaned by the cleaning blade 47 (see FIG. 4). Therefore, it is possible to prevent adverse effects due to the deposits.

FIG. 7 is a schematic diagram similar to FIG. 6, in which the width relationship of each part of the image forming system is relatively compared in different embodiments of the image forming apparatus according to the present invention. The small-sized printer as the image forming apparatus in this embodiment is different from the embodiment described in FIG. 6 in that the cleaning blade 47 shown in FIG. The only difference is that Other components are shown in FIG.
6 to FIG. 6, the illustration and description of the entire small printer are omitted.

In this embodiment, as shown in FIG. 8, the cleaning blade 47, which is a cleaning member of the cleaning means, is swung in the direction indicated by the arrow F perpendicular to the direction in which the cleaning blade 47 slides on the photosensitive drum 5. A cleaning member swinging mechanism 70 is provided.

The cleaning member swinging mechanism 70 includes a blade holding member 71 which holds the cleaning blade 47 and is swingably supported in the direction of arrow F, and a protrusion formed at the left end of the blade holding member 71. A cam 72 having a cam surface slidably in contact with a hemispherical portion at the tip of 71a; a compression coil spring 73 for urging the blade holding member 71 so as to press the hemispherical portion at the tip of the protruding portion 71a against the cam surface of the cam 72; , And a motor 74 for rotating the cam 72.

When the cam 72 is rotated once, the cleaning blade 47 swings together with the blade holding member 71 to make one reciprocation. The width of the cleaning oscillating area Wsc of the cleaning blade 47 oscillated by the cleaning member oscillating mechanism 70 is defined as the cleaning width, and the cleaning width is located in the coating portion 61 of the photosensitive drum 5. As shown in FIG. 7, a pair of tape members 18, 18 (disposed at positions corresponding to the respective tape widths Wta) are disposed within the moving area width Wsc.

According to this embodiment, the cleaning blade 47 includes the coated portion 61 and the non-coated portion 62 of the photosensitive drum 5.
Since the seam portion and the non-coating portion do not come into sliding contact with each other, it is possible to prevent the cleaning blade 47 from being turned up and to prevent it from being worn out early.

In this embodiment, the positions of the movable limits on both sides of the cleaning blade 47 oscillated by the cleaning member oscillating mechanism 70 (the cleaning oscillating area width W
(Each position on the left and right ends of SC) is the effective charging width Wa.
c. Therefore, even if a substance such as a developer adheres to the portions of the photosensitive drum 5 located at both ends of the effective charging width Wac, it can be cleaned by the cleaning blade 47. In addition, it is possible to prevent adverse effects due to the deposits.

FIG. 9 is a schematic view similar to FIG. 6 showing an embodiment of the image forming apparatus in which the cleaning width of the cleaning means is positioned inside each of the pair of tape members. It should be noted that the small printer as the image forming apparatus according to this embodiment is different from the small printer described with reference to FIGS.
Only the positional relationship in the width direction of 8, 18 is different,
Since other configurations are the same, the illustration of the configuration of each part is omitted, and the description will be made using the reference numerals used in FIGS. 1 to 6 as necessary.

In the small-sized printer according to this embodiment, the cleaning width Wc of the cleaning blade 47 is equal to the width of the tape members 18 and 18 (disposed at the positions of the left and right tape widths Wta in FIG. 9). It is located inside. Therefore, in this embodiment, the coating portion 61 (located at the portion of the coating width Wt) forming the photosensitive layer on the surface of the photosensitive drum 5 is the cleaning blade 4.
The area of the cleaning width Wc wears over time due to the sliding contact with the roller 7. On the other hand, the tape members 18, 18 on both sides
Is the cleaning width W of the cleaning blade 47.
Since the coating portions 61 are located outside of “c”, the coating portions 61 at the portions where the tape members 18 are in contact are not scraped by the cleaning blade 47.

Therefore, the cleaning width W of the coating section 61
As the area c is gradually removed by the cleaning blade 47, the gap G between the charging roller 14 and the surface of the photosensitive drum 5 described with reference to FIG. It spreads to. Therefore, in this small-sized printer, it is possible to judge that the life of the photosensitive drum 5 has reached the end of its life by utilizing the timing when the charging failure occurs. Generally, the transfer residual toner collected from the photosensitive drum 5 easily spills from both ends of the cleaning blade 47, and if it adheres to the tape member 18 after attaching again to the photosensitive drum 5, the photosensitive drum 5 The gap G between the roller 5 and the charging roller 14 may be increased. However, when the cleaning width Wc is positioned inside the tape members 18 on both sides as described above, the collected toner and the like spilled from the cleaning blade 47 hardly adhere to the tape member 18. The gap G can be prevented from increasing.

FIG. 10 is a schematic diagram similar to FIG. 7 in which the width relationship of each part of the image forming system in still another embodiment of the image forming apparatus according to the present invention is relatively compared. The small-sized printer which is the image forming apparatus in this embodiment is different from the embodiment shown in FIG. 9 in that the cleaning blade 47 is moved to the photosensitive drum 5 by the cleaning member swinging mechanism 70 in the same manner as the embodiment shown in FIG. The cleaning blade 47 swings in a direction perpendicular to the sliding direction and is swung by the cleaning member swinging mechanism 70. The cleaning swing region width Wsc of the cleaning blade 47 is defined as a cleaning width. Coating part 6 of body drum 5
1 (located in the portion of the coating width Wt), and the left and right ends of the cleaning swing region width Wsc of the cleaning blade 47 are paired with each other on both sides of the tape members 18, 18.
(Disposed at the positions of the left and right tape widths Wta in FIG. 10).

Also in this embodiment, the cleaning blade 47 includes the coating portion 61 of the photosensitive drum 5 and the non-coating portion 6 of the photosensitive drum 5.
Since the seam portion 2 and the non-coating portion do not come into sliding contact with each other, it is possible to prevent the cleaning blade 47 from being worn out early.

Further, the movement limit positions on the both sides of the cleaning blade 47 oscillated by the cleaning member oscillating mechanism 70 (the positions on the left and right ends of the cleaning oscillating region width Wsc) correspond to the tape members 18 on both sides. Since each of them is located inside, as in the embodiment of FIG.
As the portion of the cleaning swing region width Wsc is gradually cut by the cleaning blade 47, the gap G between the charging roller 14 and the surface of the photosensitive drum 5 described with reference to FIG. Therefore, it is possible to judge that the life of the photosensitive drum 5 has reached the end of its life by using the timing when the charging failure occurs with the increase of the gap G.

FIG. 11 is a schematic view similar to FIG. 6 showing an embodiment of the image forming apparatus in which the cleaning width extends outside the outer edges of the pair of tape members. The small printer that is the image forming apparatus of this embodiment is different from the small printer described with reference to FIG. 6 only in that the cleaning width Wc is set outside the outer edges of the pair of tape members 18. Are different from each other, and other configurations are the same. Therefore, the illustration of the configuration of each unit is omitted, and the description will be made using the reference numerals used in FIGS. 1 to 6 as necessary.

As described above, the pair of tape members 18, 18
Assuming that the cleaning width Wc is defined outside the outer edge of each of the above, as in the small printer described with reference to FIG.
The coating unit 61 of the photoconductor drum 5 includes the cleaning blade 4
7 (see FIG. 4), even if the area of the cleaning width Wc wears over time due to sliding contact, a pair of FIG.
1, the tape members 18, 18 respectively disposed at the positions indicated by the tape width Wta are in the width direction (the left-right direction in the figure).
Contact with plenty of time. Therefore, the gap G between the portion of the charging effective width Wac of the charging roller 14 shown in FIG. 1 and the surface of the photosensitive drum 5 can always be kept constant, whereby a good image can be obtained over time. .

FIG. 12 is a schematic diagram similar to FIG. 7 showing an embodiment of the image forming apparatus in which the cleaning width of the oscillating cleaning blade extends beyond the outer edges of the pair of tape members. . In the small printer which is the image forming apparatus in this embodiment, the cleaning blade 47 is swung by the cleaning member swinging mechanism 70 in a direction orthogonal to the direction of sliding contact with the photosensitive drum 5 as in the embodiment described with reference to FIG. The cleaning swing width Wsc of the cleaning blade 47 which is swung by the cleaning member swing mechanism 70 is defined as a cleaning width, and the cleaning width is a pair of the tape members 18 and 1.
8 (disposed at the positions of the left and right tape widths Wta in FIG. 12), respectively, only in the point that they are located outside the outer edges.

Such a cleaning swing region width Wsc
Is the cleaning width, as in the case of the small-sized printer described with reference to FIG. 7, the coating portion 61 of the photosensitive drum 5 wears the area of the cleaning width Wc with time due to the sliding contact of the cleaning blade 47 (see FIG. 4). Even so, the pair of tape members 18, 18 contact the worn portion with a margin in the width direction (left-right direction in FIG. 11). Therefore, also in this embodiment, the gap G between the portion of the charging effective width Wac of the charging roller 14 shown in FIG. 1 and the surface of the photoconductor drum 5 can be always kept constant, and thereby, even over time. Good images can be obtained.

FIG. 13 is a front view showing an embodiment in which the gap management member is a roller. The gap management member of this embodiment includes rollers 81, 81 attached to both ends of a cored bar 16 formed of a metal shaft of the charging roller 14 '.
It is. Its roller 81, for example, the outer diameter _{D 2} of rubber, the outer diameter _{D 1} of the charging roller 14 'conductive rubber roller portion 17'
The gap G (for example, 100 μm or less) is formed by the difference between the outer diameters D ₁ and D ₂ .

Also in this embodiment, the pair of rollers 81, 81 are both in contact with the non-charged area of the coating section 61 which is softer than the non-coating section 62 of the photosensitive drum 5. Therefore, even if the above-mentioned gap G is set to, for example, 100 μm or less, the roller 81 is hard to be worn, so that the gap G can be maintained at a gap amount capable of favorably charging for a long period of time.

While the various embodiments of the image forming apparatus according to the present invention have been described above, in each of the embodiments, the charging rollers 14 and 14 ′ are provided with a metal core (metal shaft) 16.
When a voltage is applied between the photoconductor drum 5 and both ends of the metal core 16, the both ends of the metal core 16 are not coated at positions where no leakage occurs from the both ends of the metal core 16 to the non-coated portion 62 of the photoconductor drum 5. Part 62
It is good to place it away from.

[0080]

As described above, according to the present invention, the following effects can be obtained. According to the image forming apparatus of the present invention, the gap management member contacts the coating portion of the image carrier to form a predetermined gap between the charging member and the surface of the image carrier. Wear and damage of the gap management member can be reduced as compared with a case where the management member is brought into contact with a non-coating portion formed of a material harder than the coating portion. Therefore, the gap between the charging member and the surface of the image carrier can be kept substantially constant for a long period of time because the gap management member is less likely to be worn.

According to the image forming apparatus of the present invention, since the gap management member is in contact with the cleaning width of the surface of the image carrier, the area of the cleaning width on the surface of the image carrier is reduced. Even if the cleaning means slides and wears with time, the gap between the charging member and the surface of the image carrier can be kept constant by the gap management member coming into contact with the worn part. Thereby, a good image can be obtained over time.

According to the image forming apparatus of the present invention, the coating portion on which the photosensitive layer of the image bearing member is formed has a predetermined width since the cleaning width region is worn with time due to sliding contact by the cleaning means. When the use time is reached, the life of the image carrier reaches the end of its life. However, in this image forming apparatus, since the cleaning width of the cleaning unit is located inside the gap management member, the coating of the portion in contact with the gap management member is performed. The part is not worn by the cleaning means.

Accordingly, as the cleaning means gradually removes the area of the cleaning width of the coating section, the gap between the charging member and the surface of the image carrier gradually increases, and the time when charging failure occurs may occur. come. Therefore,
Utilizing the timing of the occurrence of the charging failure, it can be determined that the life of the image carrier has reached the end of its life. In general, when the cleaning width is up to the position of the gap management member, when transfer residual toner or the like collected from the image carrier spills from both ends of the cleaning unit, the gap remains after the toner adheres to the image carrier again. When the toner adheres to the management member, the gap between the image carrier and the charging member may increase. However, if the cleaning width is located inside the gap management member as described above, the cleaning width may be spilled from the cleaning unit. Since the collected toner and the like can be made hard to adhere to the gap management member, an increase in the gap can be prevented.

According to the image forming apparatus of the present invention, since the cleaning member is oscillated by the cleaning member oscillating mechanism, it is possible to prevent paper dust and the like from being continuously caught between the cleaning member and the surface of the image carrier. Since the cleaning member does not come out of the area of the coating portion even if it is swung, the cleaning member is not connected to the coating portion and the non-coating portion of the image carrier, or the non-coating portion. It is possible to prevent the cleaning member from being turned up or worn out early due to the sliding contact of the processed portion.

According to the image forming apparatus of the present invention, the cleaning blade of the cleaning means does not slidably contact the coating portion of the image carrier with the non-coating portion or the non-coating portion. The turning of the cleaning blade can be prevented, and the wear of the cleaning blade at an early stage can be prevented.

According to the image forming apparatus of the seventh and tenth aspects, in general, the charging potential becomes unstable near both ends of the effective charging width on the surface of the image carrier, so that the developer easily adheres there. However, by making the effective transfer width of the transfer member narrower than the effective charge width of the charging means, it is possible to prevent the developer attached near the outside of both ends of the effective charge width from being transferred to the transfer member.

According to the image forming apparatus of the present invention, since the developing width of the developing device is smaller than the effective charging width of the charging means, the developer adheres to the vicinity of both ends of the effective charging width on the image carrier. Can be prevented. Therefore, it is possible to prevent the developer from entering between the gap management member and the surface of the image carrier to increase the gap, and the developer adheres to the vicinity of both ends of the effective charging width. Problems that occur in the case can be prevented.

According to the ninth aspect of the present invention, the developing width is smaller than the effective transfer width, and the effective transfer width is smaller than the effective charging width. Is difficult to adhere near both ends.

According to the image forming apparatus of the present invention, even if the deposits such as the developer adhere to the portions located at both ends of the effective charging width on the image carrier, the portions are cleaned by the cleaning means. Therefore, it is possible to prevent adverse effects due to the attached matter.

According to the image forming apparatus of the twelfth aspect, it is possible to prevent paper dust and the like from continuing to be caught between the cleaning member and the surface of the image carrier, and to limit both ends of the effective charging width on the image carrier. When a deposit such as a developer adheres to the portion located in the area, it can be cleaned by the cleaning member, so that adverse effects due to the deposit can be prevented.

According to the image forming apparatus of the thirteenth aspect, since the gap management member is a pair of tape members, it can be easily fixed by winding it around both ends of the elastic portion of the charging member. it can. Therefore, workability when attaching the gap management member can be improved.

According to the image forming apparatus of the present invention, since the tape member is formed to have a very small thickness of 100 μm or less, when the tape member is worn by contact with the surface of the image carrier, the initial thickness is reduced. The effect of the thickness reduction ratio on the thickness is very large. Therefore, by bringing the tape member into contact with the coated portion that is softer than the non-coated portion, the effect of reducing abrasion is great.

According to the image forming apparatus of the present invention, the pair of tape members are wound around both ends of the elastic portion such that there is no portion where the tape member does not exist in the axial direction of the roller at all positions around the circumference. Therefore, even if the film material portions at both ends thereof are brought into contact with the image carrier and rolled, the image carrier periodically drops between the circumferential edges of each film material. Can be prevented. Therefore, it is possible to prevent the occurrence of micro-vibration that occurs when the image carrier falls between the edges.

According to the image forming apparatus of the present invention, both ends of the pair of tape members are cut obliquely so that the cut edges face each other, and a gap is formed between the cut ends. With this configuration, it is possible to prevent both ends in the circumferential direction of the film material from overlapping with each other even if the length of the film material in the winding direction is not so strictly controlled.

According to the image forming apparatus of the seventeenth aspect, the angle of inclination of the cut lines of the obliquely cut portions at both ends of each of the pair of tape members with respect to the side edge of the tape member is substantially 4 degrees.
Since it is formed at 5 degrees, it is possible to increase the contact width of the film material with the image carrier at the joint portion of the film material while preventing the ends at both ends of the film material from being easily peeled off.

According to the image forming apparatus of the eighteenth aspect, the charging roller is provided with the two ends of the metal shaft at the positions where no leakage occurs from both ends of the metal shaft to the non-coated portion of the image carrier. Since it is located away from the charging roller, it is possible to prevent leakage from the metal shaft of the charging roller to the non-coated portion of the image carrier, thereby obtaining good charging performance.

According to the image forming apparatus of the present invention, since the gap management member is a roller attached to each end of the metal shaft of the charging roller, even when the charging member is a charging roller having an elastic portion, Instead of wrapping a tape-shaped gap management member around both ends of the elastic portion, the roller is brought into contact with the surface of the image carrier to thereby form a portion of the effective width of the charging member and the surface of the image carrier. And a predetermined gap can be formed between them.

Accordingly, when the tape-shaped gap management member is wound around the elastic portion of the charging roller, the elastic portion of the portion around which the gap management member is wound is deformed by the force of pressing the charging roller toward the image carrier, and the above-mentioned deformation occurs. The gap may be narrowed, but this can be prevented. According to the image carrier unit of claim 21,
Since the image carrier and the charging member are formed as an integral unit, maintenance of the image carrier and the charging member can be easily performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a charging roller and a photosensitive drum included in an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing one end of the charging roller.

FIG. 3 is an overall configuration diagram showing a color small printer as the image forming apparatus.

FIG. 4 is a configuration diagram showing a photosensitive unit provided in the small printer.

FIG. 5 is a configuration diagram showing a writing unit provided in the small printer of FIG. 3;

FIG. 6 is a schematic diagram in which the width relations of respective units constituting the image forming system of the small printer of FIG. 3 are relatively compared.

FIG. 7 is a schematic diagram similar to FIG. 6, in which the width relationship of each part of an image forming system in different embodiments of the image forming apparatus according to the present invention is relatively compared.

FIG. 8 is a schematic diagram for explaining a cleaning member swing mechanism of the image forming apparatus.

FIG. 9 is a schematic diagram similar to FIG. 6, illustrating an embodiment of an image forming apparatus in which a cleaning width of a cleaning unit is positioned inside each of a pair of tape members.

FIG. 10 is a schematic diagram similar to FIG. 7, in which the width relationship of each part of an image forming system in still another embodiment of the image forming apparatus according to the present invention is relatively compared.

FIG. 11 is a schematic diagram similar to FIG. 6, illustrating an embodiment of an image forming apparatus in which a cleaning width is set outside the outer edges of a pair of tape members.

FIG. 12 is a schematic diagram similar to FIG. 7, illustrating an embodiment of the image forming apparatus in which the cleaning width of the oscillating cleaning blade extends beyond outer edges of a pair of tape members.

FIG. 13 is a front view showing an embodiment in which the gap management member is a roller.

FIG. 14 is a schematic view showing an example of a conventional charging roller.

[Explanation of symbols]

2A, 2B, 2C, 2D: Photoconductor unit (image carrier unit) 3: Transfer belt (transfer member) 4: Charging device (charging means) 5: Photoconductor drum (image carrier) 10A, 10B, 10C, 10D : Developing device 14, 14 ': charging roller (charging member) 16: metal core (metal shaft) 17, 17': conductive rubber roller portion (elastic portion) 18: tape member (gap management member) 47: cleaning blade (cleaning) 61): Coating part 62: Non-coating part 70: Cleaning member swing mechanism 81: Roller

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ugitsu Ugitsu 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hitoshi Ishibashi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Iwasakisaki Yukiko 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. Masami Hiramatsu 1-3-6 Nakamagome, Ota-ku, Tokyo F-term (Reference) 2H077 AD06 BA10 DB12 DB14 DB15 EA03 EA24 GA13 2H134 GA01 GB02 HD10 KG01 KG03 KG04 KG08 KH15 KJ02 2H200 FA09 FA19 GA23 GA45 GA47 GB12 HA13 HA28 HB12 HB20 HB22 HB40 LA02

Claims (21)

[Claims] 1. An image bearing member having a coating portion for forming a photosensitive layer and non-coating portions formed on both sides thereof with a material harder than the coating portion, and the coating portion of the image bearing member. An image forming apparatus comprising: a charging unit having a charging member for charging; and An image forming apparatus, wherein a predetermined gap is formed between the charging member in a portion of the effective charging width of the charging unit and the surface of the image carrier. 2. The image forming apparatus according to claim 1, wherein
Cleaning means for cleaning the image bearing member with a predetermined cleaning width by being in sliding contact with the coating portion, wherein the gap management member is positioned within the cleaning width of the cleaning means. Image forming device. 3. The image forming apparatus according to claim 2, wherein the cleaning width extends outside an outer edge of the gap management member. 4. The image forming apparatus according to claim 1, wherein
A cleaning unit for cleaning the coating portion of the image carrier by a predetermined cleaning width by sliding the coating unit, wherein the cleaning width of the cleaning unit is located inside the gap management member. Image forming apparatus. 5. The image forming apparatus according to claim 2, wherein the cleaning member of the cleaning unit is swung in a direction perpendicular to a direction in which the cleaning member slides on the image carrier. An image forming apparatus comprising a cleaning member swinging mechanism, wherein a width of a cleaning swinging area of the cleaning member which is swung by the cleaning member swinging mechanism is set to the cleaning width. 6. The cleaning unit according to claim 2, wherein the cleaning unit is a unit that slides a cleaning blade on the coating unit of the image carrier to clean the coating unit. An image forming apparatus according to claim 1. 7. The image forming apparatus according to claim 1, further comprising a transfer member that transfers a visible image formed on a surface of the image carrier to a transfer material. Wherein the effective width of the transfer is smaller than the effective width of the charging means. 8. The image forming apparatus according to claim 1, further comprising a developing device that develops a latent image on the image carrier with a developer to form a visible image. An image forming apparatus, wherein a developing width of the apparatus is narrower than an effective charging width of the charging unit. 9. The image forming apparatus according to claim 7, wherein
An image forming apparatus, comprising: a developing device that develops a latent image on the image carrier with a developer to convert the latent image to a visible image, wherein a developing width of the developing device is narrower than an effective transfer width. 10. The image forming apparatus according to claim 8, wherein the developer is a two-component developer using a toner and a carrier. 11. The image forming apparatus according to claim 2, wherein the cleaning width is wider than the effective charging width. 12. The image forming apparatus according to claim 2, further comprising a cleaning member oscillating mechanism for oscillating the cleaning member of the cleaning unit in a direction perpendicular to a direction in which the cleaning member slides on the image carrier.
The image forming apparatus according to claim 1, wherein the positions of the movable limits on both sides of the cleaning member that are swung by the cleaning member swinging mechanism are located outside the effective charging width. 13. The charging member is a charging roller having an elastic portion formed on a portion other than both ends of an outer peripheral surface of a metal shaft, and the gap management member is a pair of tapes fixed to both ends of the elastic portion. 13. The image forming apparatus according to claim 1, wherein the width between the insides of the pair of tape members is the effective charging width. 14. 14. The image forming apparatus according to claim 13, wherein said tape member is formed to have a thickness of 100 μm or less. 15. The image forming apparatus according to claim 13, wherein the pair of tape members is wound around both ends of the elastic portion in a circumferential direction, and the circumferential ends of the pair of tape members do not overlap with each other, and the entire circumference thereof does not overlap. The image forming apparatus is fixed so that there is no portion where the tape member does not exist in the axial direction of the roller at the position (1). 16. The tape member according to claim 1, wherein both ends of the pair of tape members are cut obliquely so that edges of cut edges are opposed to each other, and a gap is formed between the cut edges. Item 16. An image forming apparatus according to Item 15. 17. The tape device according to claim 16, wherein a slant angle of a cut line of a portion cut obliquely at both ends of the pair of tape members with respect to a side edge of the tape member is substantially 45 degrees. Image forming apparatus. 18. The charging roller according to claim 1, wherein when a voltage is applied between the metal shaft and the image carrier, the charging roller is located at a position where no leakage occurs from both ends of the metal shaft to a non-coated portion of the image carrier. The image forming apparatus according to any one of claims 13 to 17, wherein both ends of the metal shaft are arranged apart from the uncoated portion. 19. The charging member is a charging roller having an elastic portion formed at a portion other than both ends of an outer peripheral surface of a metal shaft, and the gap management member is attached to both ends of the metal shaft of the charging roller. The image forming apparatus according to claim 1, wherein the roller is a roller. 20. A gap management member comprising: an image carrier having a photosensitive layer; and charging means having a charging member for charging the image carrier, wherein the charging member is brought into contact with a non-charged area of the image carrier. Contact the surface of the image carrier via
An image forming apparatus in which a predetermined gap is formed between the charging member and the surface of the image carrier, wherein a cleaning unit for cleaning with a predetermined cleaning width by slidably contacting the surface of the image carrier is provided. ,
An image forming apparatus, wherein the gap management member is located within the cleaning width of the cleaning unit. 21. An image carrier unit mounted on the image forming apparatus according to claim 1, wherein said image carrier and said charging member are integrally provided. unit.