JPH0450954A - Image forming device - Google Patents

Abstract

PURPOSE:To constitute a device to be compact and inexpensive and to reduce power consumption by arranging an erasing means in an image forming cartridge. CONSTITUTION:The erasing means 45 consisting of an LED array for removing residual charge on the surface of a photosensitive drum 4 after transfer is performed is disposed in a space between a cleaning blade 7 in the image forming cartridge 1 and an electrostatic charger 52 so that it may be approximately opposed to the drum 4. A driving current for the means 45 is supplied in a state where the means 45 is connected to an electrode provided in the cartridge 1 by attaching the means 45 to the cartridge 1. Since the means 45 is disposed so that it may be approximately opposed to the drum 4, the residual charge is surely removed even when light output becomes large, the device is made compact and inexpensive and the power consumption is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, or a printer that forms an image using an electrophotographic method, and particularly relates to an image forming apparatus such as an image carrier, a developing means, a cleaning means, etc. The present invention relates to an image forming apparatus in which an image forming cartridge having an integral combination of means is removably attached to an apparatus main body.

BACKGROUND ART This type of image forming apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-2798.
It is known from Publication No. 72, etc. In the image forming apparatus disclosed in this publication, in order to easily replace consumables such as the image carrier, an image carrier, a developing means for developing a latent image, and a An image forming cartridge is used which integrally combines a cleaning means for removing residual toner and a charger. In addition, in order to uniformly charge the image carrier with a charger, an erase lamp that irradiates the image carrier with light to remove residual charges before charging is installed above the image forming cartridge mounting space in the main body of the device. A slit is formed on the upper surface of the casing of the image forming cartridge so that light from the erase lamp is irradiated onto the image carrier.

Problems to be Solved by the Invention However, in the above configuration, since an image forming cartridge is used, the erase lamp is placed at a position away from the image carrier, and therefore, as an erase lamp, the light output is large and the axis of the image carrier is It is necessary to have a luminous intensity that is almost uniform over the entire length in the direction, and it is necessary to use an expensive lamp such as a rod-shaped halogen lamp, which increases the cost, consumes a lot of power, and generates a large amount of heat, so thermal measures for the laser light source are required. There were problems such as the need for

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that uses an image forming cartridge and can use an inexpensive erase means that has low output and generates little heat.

Means for Solving the Problems In order to achieve the above problems, the present invention provides an integral combination of an image bearing member, a developing means, a means for cleaning the image bearing member after transfer, and a charging means. An image forming apparatus in which an image cartridge is removably attached to an apparatus main body, characterized in that an erase means for removing electric charge remaining on an image carrier before charging is disposed in the image forming cartridge. It is.

Function In the above structure of the present invention, since the erase means is disposed within the image forming cartridge, the erase means can be disposed close to the image carrier even in an image forming apparatus using the image forming cartridge. As a result, it is possible to use an LED array or the like as the erasing means, which is more compact, cheaper, consumes less power, and generates less heat than a halogen lamp or the like. Furthermore, if a method is adopted in which the developer in the image forming cartridge is used up, the image forming cartridge is collected and toner is refilled, and by cleaning the erase means at the time of replenishment, the toner can be placed in the image forming cartridge. Even if it gets dirty, it will not deteriorate its functionality.

Embodiment An embodiment in which the present invention is applied to a printer will be described below with reference to FIGS. 1 to 6.

First, the basic structure of an image forming cartridge 1, which is a main part of a printer, will be explained based on FIG. In FIG. 1, an image forming cartridge 1 is formed by connecting a developer casing 2 and a waste toner casing 3 as shown. A photosensitive drum 4 is provided at the connecting end of the waste toner casing 3 and is pivotally supported on the side wall of the waste toner casing 3 by a shaft 6. A cleaning blade 7 is brought into pressure contact with the back of the photosensitive drum 4, and residual toner scraped off from the top of the photosensitive drum 4 is stored in the waste toner casing 3. To accommodate this, a paddle 8 is provided near the bottom of the waste toner casing 3 behind the photosensitive drum 4 to scrape the toner scraped from the photosensitive drum 4 into the waste toner casing 3. The photosensitive drum 4 has a photoconductive layer made of zinc oxide, selenium, organic photoconductive material, etc. formed on the surface of a metal base such as aluminum, and forms an electrostatic latent image by imagewise exposure.

A developing roller 1 for developing the electrostatic latent image on the photosensitive drum 4 with toner is provided at the connecting end of the developing device casing 2, and is pivotally supported on the side wall by a shaft 12. A fur brush 13 is provided on the back of the developing roller 11 and is pivotally supported by a shaft 14 on the side wall of the developing device casing 2 . Inside the developer casing 2 is a developer supply paddle 15 that agitates the developer in the developer casing 2 while supplying it to the fur brush 13.
is provided and is pivoted to the side wall by a shaft 16. A stirring blade 17 is attached to the shaft 16 to prevent the toner from forming blocks.

A wire 82 for scraping off the developer is provided on the back of the fur brush 13. This wire 82 is stretched between the opening edges of a partition plate 95 in the developer casing 2.
It is pressed against the back surface of the fur brush 13. As a result, when the residual developer that has been supplied to the developing roller 11 on the fur brush 13 returns to the back side of the fur brush 13, this residual developer is scraped off from the surface of the fur brush 13 by the wire 82. Returned to unused developer. Therefore, the residual developer remaining after being supplied to the developing roller 11 does not leave the surface of the developing roller 11 and is repeatedly supplied to the developing roller 11 as it is, or -
Even if it is scraped off from the surface of the developing roller 11, it is avoided that it is caught by the fur brush 13 and supplied to the developing roller 11 without being mixed with unused developer. Therefore, it is possible to prevent the stress of the residual developer that is not supplied to the developing roller 11 on the fur brush 13 from affecting the developing characteristics.

The developer casing 2 and the waste toner casing 3 are connected to the shaft 2.
Positioning rollers 23 and 24 provided on the shafts 6 and 12 of both the photosensitive drum 4 and the developing roller 11 are connected to each other so as to be swingable by the shafts 6 and 1 of the photosensitive drum 4 and the developing roller 11.
They are brought into pressure contact with each other, and a predetermined gap is maintained between the photosensitive drum 4 and the developing roller 11 while absorbing manufacturing and assembly errors of each part.

M2O is attached to an upwardly opened developer input port 83 of the developer casing 2, and is fixed to the developer casing 2 by an appropriate method such as adhesion, welding, or screwing. This 1iE30 extends to the Ji toner casing 3 and covers the waste toner casing 3, making it easy to handle it as an integral part of the image forming cartridge 1.

In particular, the lid 30 is heavier than the waste toner casing 3 and is fixed to the side of the larger developer casing 2 to serve as the gripping portion H for integral handling, which improves the stability of the image forming cartridge nozzle during handling. , it becomes even easier to handle. Note that a play is provided between the lid 30 and the waste toner casing 3 to an extent that does not prevent the necessary rocking of the waste toner casing 3 relative to the developer casing 2 due to pressure contact between the positioning rollers 23 and 24.

Further, a sealing plate 25 is provided at the bottom of the connecting end opening of the developer casing 2 and extends to the circumferential surface of the developing roller 11 and comes into pressure contact therewith. A seal plate 26 is provided that extends to the drum 4 and presses against it. As a result, the developer handling space of the image forming cartridge 1 formed by the developer casing 2 and the waste toner casing 3 becomes almost sealed, thereby preventing the developer from scattering to the outside. I can do it.

Note that the sealing performance can be further improved by providing the seal plates 25 and 26 in the developer casing 2 and the waste toner casing 3 in multiple stages as necessary, and pressing them against the surfaces of the developing roller 11 and the photosensitive drum 4 in multiple stages in their rotational directions. improves.

However, due to recent miniaturization and weight reduction, the thickness of each member forming the image forming cartridge 1 tends to become thinner and the rigidity tends to decrease. Therefore, when handling the image forming cartridge 1 alone, an external force for gripping the image forming cartridge 1 acts on the developing device casing 2 forming the grip part H of the image forming cartridge 1, causing temporary deformation such as twisting or denting. It may also occur. At this time, the volume of the developer casing 2 momentarily decreases, and the developer may be blown out along with the internal air from the weak portion of the seal.

Therefore, in this embodiment, an opening 84 is formed in the lid 30, and the opening 84 is closed with a semipermeable membrane 85. The semipermeable membrane 85 is one that allows air to pass through but does not allow the developer to pass through. As a result, even if the developer casing 2 is deformed as described above during handling of the image forming cartridge 1 and the volume is reduced and internal air is blown out, the semi-permeable membrane 85 with less resistance prevents the air from blowing out. Even if the developer tries to get onto the blown air, the semi-permeable membrane 8
5 to prevent it from spewing out to the outside. Such a structure can be applied to the waste toner casing 3 as well, if necessary.

This image forming cartridge 1 is used by being attached to a printer 31 as shown in FIG. In this printer 31, an upper frame 33 can be opened and closed vertically about a hinge shaft 34 with respect to a lower frame 32, and the image forming cartridge 1 is mounted on the upper frame L33 as shown by the arrow. This attachment is performed detachably from the rear of the upper frame 33 that opens upwardly along guides (not shown) provided inside both side walls of the upper frame 33. Thereafter, by closing the upper frame 33 with respect to the lower frame 32, the image forming cartridge 1 forms a paper passing bus 37 for printing between it and the transfer charger 36 provided on the lower frame 32 side. On the other hand, when the upper frame 33 is opened upward as shown in FIG. 2, the paper passing bus 37 is opened, and problems such as jams can be easily dealt with.

A laser scanning unit 38 is provided above the portion of the upper frame 330 where the image forming cartridge 1 is mounted. This laser scanning unit 38 deflects a laser beam 39 from a laser emitting source modulated according to an image signal provided by a personal computer, image league, etc. using an appropriate scanning means such as a polygon mirror, and scans the photosensitive drum 39. Image exposure is performed on the photosensitive drum 4 toward the image. For this image exposure, an exposure slit 51 is provided in a part of the lid 30 of the image forming cartridge 1 to enable image exposure to the photosensitive drum 4. A charging charge +52 for uniformly charging the surface of the photosensitive drum 4 is provided in front of the image exposure position of the photosensitive drum 4 so that an image is formed.

As shown in FIG. 1, in the narrow space between the cleaning blade 7 and the charging charger 52 in the image forming cartridge 1, erase light is irradiated onto the surface of the photosensitive drum 4 after transfer. LE to remove residual charge
An erase means 45 consisting of a D array is disposed so as to be close to and face the photosensitive drum 4. A driving current for the erase means 45 is supplied by connecting the erase means 45 to an electrode provided on the image forming cartridge 1 by mounting the erase means 45 on the image forming cartridge 1.

Since the erase means 45 is disposed close to and facing the photosensitive drum 4 in this way, residual charges can be reliably removed even if the light output is not as large as that of a halogen lamp. Furthermore, the LED array is compact and inexpensive, and has low power consumption and heat generation, so it is suitable for disposing within the image forming cartridge 1. Furthermore, when the developer in the developer casing 2 is consumed and the image forming cartridge 1 is collected and the developer is replenished, if the LED array is cleaned, even if it is placed inside the image forming cartridge Fuji 1, it will become dirty. There is no risk of functional deterioration due to the use of the battery, and it can be used effectively until its lifespan.

As shown in detail in FIGS. 4 and 5, an elastic blade 41 is pressed against the developing roller 11. As shown in FIGS. As the elastic blade 41, a rubber blade made of urethane rubber, silicone rubber, or the like, or a metal blade made of spring-use phosphor bronze, spring steel, or the like is useful. The upper end of the elastic blade 41 is attached by adhesive or the like to a metal support member 42 that is stretched between the side walls of the developer casing 2, and the lower end is pressed against the surface of the developing roller 11.

Incidentally, the developing roller 11 has a developer carrying area X on the central side in the longitudinal direction formed with a satin surface by sandblasting or the like, which is advantageous for carrying the developer. Both ends of the developing roller 11 on both sides of the developer carrying area be. For this reason, the developer non-carrying area Y is kept as a smooth surface to avoid carrying the developer.

As a result, the developer carrying area X of the developing roller 11 has a satin-like unevenness formed on its surface, and the convex portion rises from the surface of the fabric, so that the diameter thereof is slightly increased compared to the developer non-carrying area Y. In addition, since the developer carrying area X of the developing roller 11 carries the developer supplied from the sponge roller 13, although the developer is thinned to a predetermined layer thickness by pressure contact with the elastic blade 41, the developing roller The diameter of the developer carrying area X portion of No. 11 is further increased. Therefore, the diameter of the developer carrying area X of the developing roller 11 is somewhat different from that of the developer non-carrying area Y, and there is a gap between the developer carrying area X and the developer non-carrying area Y of the developing roller 11. Step Z
(Figure 5) will occur.

Therefore, if the elastic blade 41 is uniformly and continuously pressed over the entire length of the developing roller 11, it will not carry the developer, and moreover, the developer non-carrying area Y will have a small diameter.
Floating occurs between the two and causes the developer to leak forward.

In order to solve this problem, in this embodiment, a notch 86 cut from the tip is formed in the portion of the elastic blade 41 facing the boundary K between the developer carrying area X and the developer non-carrying area Y of the developing roller 11. is forming. As a result, the elastic blade 41 is divided by the notch 86 into the center side in the longitudinal direction facing the developer carrying area X and the developer non-carrying area Y of the developing roller 11, and the sections 41a and 41b on both sides thereof. Since the respective portions 41a and 41b independently press against the developer carrying area X and the developer non-carrying area Y of the developing roller 11 without being influenced by each other, there is a step Z between the respective areas X and Y. Part 4 of the elastic blade 41
1b can be brought into close contact with the portion of the developer non-carrying area Y as shown in FIG. 5, regardless of the portion 41a of the elastic blade 41 that is pushed away by the developer in the developer carrying area χ. Therefore, the elastic blade 41
It is possible to eliminate the inconvenience in which the developer floats from the developing roller 11 in the developer non-carrying area Y and the developer leaks from the developer non-carrying area Y to the photosensitive drum 4 side.

Further, the portion 41b of the elastic blade 41 is attached to the support member 42.
It is held down by presser metals 57 attached to both ends of the holder, which further prevents it from lifting up. Developing roller 1
A sealing material 88 is interposed between 1 and the side wall 87.

Furthermore, in a long continuous portion of the elastic blade 41 in the longitudinal direction, pressure contact with the developing roller 11 tends to be stronger in the central portion of the continuous range than in other portions.
The layer thickness of the developer formed on the developing roller 11 tends to be non-uniform in the axial direction of the developing roller 11, which causes uneven development characteristics. Therefore, in this embodiment, in order to solve this problem,
A groove 81 as shown in FIGS. 1 and 4 is formed on the back surface of the elastic blade 41. This groove 81 is located approximately at the center in the width direction of the elastic blade 41, and is formed in a range excluding both ends of the portion 41a between the long cuts 86 of the elastic blade 41.

This allows the long portion 41a of the elastic blade 41 to
The bending rigidity at the central portion in the longitudinal direction is weakened by the concave groove 81, the pressing force against the developing roller 11 is reduced, and the pressing force against the developing roller 11 of the entire long portion 41a of the elastic blade 41 is reduced. become even.

Furthermore, stress is concentrated in the concave groove 81 portion of the elastic blade 41, and by equalizing the stress in other portions, the pressing force against the developing roller 11 can be made uniform.

Therefore, a thin layer of developer can be formed with a uniform layer thickness over the entire developer carrying area X of the developing roller 11, and uniform development characteristics can be expected over the entire developer carrying area X of the developing roller 11.

In addition, the elastic blade 41 is made of polyethylene terephthalate (
If it is formed by punching from a sheet such as PET, the cost will be lower than when a molded product such as urethane foam is used. In this case PET
Since it is made of a strong material, it does not damage the developing roller 11 or cause chattering, and it is preferable to press the developing roller 11 at the so-called abdomen in order to avoid contact with the tip edge.

Furthermore, since the elastic blade 41 is made of an insulating material, the frictional charging between the developer and the elastic blade 41 can be increased, and the overall charging state can be sufficiently stabilized. In this sense, forming a coating layer of an insulating material on the surface of the developing roller 11 can further improve the charging characteristics. In addition, since the insulating coating layer can form a satin surface during resin molding without sandblasting, the cost of the boundary image roller 11 is reduced accordingly, and the developer can be conveyed onto the head where the electric field is not diffused. At the same time, the gap between the developing roller 11 and the photosensitive drum 4 can be shortened beyond the discharge limit.
Resolution in development is improved.

As another example, an insulating elastic roller may be used instead of the elastic blade 41, in which case the developing roller 11
You can set the relative speed in any way you like. This allows the charging characteristics to be adjusted in various ways,
Depending on whether the elastic roller is rotated in a subordinate direction to the developing roller 11 or in the opposite direction, the surface layer of the developer on the developing roller 11 is actively subjected to development;
It becomes possible to select whether to make it difficult to be subjected to development. Such selection is based on the developer, developer supply mechanism, and photosensitive drum 4.
This is useful when dealing with various types of image forming conditions, such as types, etc., or when responding to special requests.

In addition, a speed change mechanism is provided in the drive system of the developing roller 11 to increase the rotational speed of the developing roller 11 when forming an image with poor reproducibility such as a line drawing or a dot image. Increasing the supply amount improves reproducibility even for line drawings and dot drawings.

In this embodiment, the configuration of the charger 52 is devised in response to the fact that the photosensitive drum 4 is designed to have an extremely small diameter. The photosensitive drum 4, which has an extremely small diameter, faces the charging charger 52 on a curved surface with a sharp degree of curvature, and it is difficult to perform stable charging due to the influence of higher speeds. Therefore, the charger 52 connects the mesh of the grid section 530 to the photosensitive tram 4.
It is arranged so that it gradually becomes finer from the upstream side to the downstream side in the direction of rotation (Figs. 1 and 3). As a result, the charging charger 52 is initially a corotron type charger without a grid or exhibiting charging characteristics similar to that to ensure charging performance for the rotating photosensitive drum 4, and then a scorotron type charger with a grid. This ensures controllability of charging by exhibiting charging characteristics as described above.

This makes it possible to achieve stable charging by ensuring both charging performance and charging controllability.

Although the charger 52 is formed into one for miniaturization, two chargers, a corotron type charger and a scorotron type charger, may be installed. Further, the size of the mesh may change continuously or discontinuously. , the charger 52 has a grid section 5 for miniaturization.
3 and a discharge stabilizing frame 54 are integrally formed from a metal plate. The corona wire 55 is installed between resin blocks 56 attached to both side walls of the developer casing 2, and the ends of the discharge stabilizing frame 54 are held by the resin blocks 56.

Note that the corona wire 55 has a thin wire diameter of about 80 μm, so there is a problem with elongation and cutting, which makes it troublesome to handle during installation, and maintenance such as cleaning when it becomes dirty due to use is also troublesome. Therefore, it is conceivable that a metal plate is buried in a resin base (not shown) by insert molding or the like, and a part of the buried metal plate is exposed to be used in place of the corona wire. In this case, costs can be reduced and the strength of the corona electrode portion is improved, making assembly and cleaning easier. Alternatively, a predetermined metal material may be printed in a line shape on the surface of the resin base to serve as a substitute for the corona wire. In this case as well, the same effects as the above improvements can be expected.

Further, the discharge stabilizing frame 54 can also be formed by applying metal plating to the inner surface of the resin housing. In this case, the resin housing can be integrally formed with a part of the existing member such as the lid 30, and the structure can be simplified.

The transfer charger 36 is disposed so as to face the photosensitive drum 4 of the image forming cartridge 1 with a certain gap when the upper frame 33 is closed on the lower frame 32.

A timing roller pair 61 is provided in front of the transfer section of the paper passing path 37, as shown in FIG. The timing roller pair 61 temporarily stops receiving the transfer paper 91 which is pink-stacked and fed by the pickup roller 93 from the paper feed force center 92 in a stopped state, and then feeds the transfer paper 91 at a predetermined timing and is exposed to light. The leading edge is aligned with the toner image formed on the drum 4 and used for transfer.

A pair of fixing rollers 62 is provided behind the transfer section, and heat fixes the transfer sheet fed after the transfer.

The surface of the photosensitive drum 4 after the transfer is cleaned by a cleaning blade 7 to remove residual toner. Further, like the elastic blade 41, the cleaning blade 7 can also have a groove formed on its back to equalize the pressure contact force. In this case, the resonant frequency of the blades can be easily selected. Furthermore, the cost can be reduced by punching out a PET sheet.

As shown in FIG. 6, the waste toner casing 3 is provided with an unused detection mechanism 71 that is linked to the drive system. This unused detection mechanism 71 is a gear 73 provided on one shaft of the drive system, for example, the rotating shaft 72 of the paddle 8 for scraping in waste toner.
The detection gear 74 is engaged. The detection gear 74 has teeth 75 only on a part of the outer periphery, and the other part of the outer periphery is a cam surface 77 having a recess 76 in a part. The waste toner casing 3 also includes a detection bin 78 facing the cam surface 77.
is held movably forward and backward, and this detection pin 78 is brought into contact with the cam surface 77 by a spring 79. When the image forming cartridge 1 is not in use, that is, when the drive system has never been operated and no developer is consumed, this abutment position is set a predetermined amount downstream from the recess 76 of the cam surface 77 in the driving direction. It's a position where I can do it.

When the image forming cartridge 1 is installed in the printer 31 and is driven and used even once, the gear 7 that is interlocked with the drive is activated.
3 rotates the detection gear 74. The concave portion 76 of the cam surface 77 faces the detection bin 78 by a small amount of rotation compared to the amount of drive for use. At this opposing position, the detection bottle 78 is fitted into the recess 76 by the force of the spring 79.

The detection bin 78 protrudes outside the waste toner casing 3 when the image forming cartridge 1 is not in use, and when the image forming cartridge 1 is mounted on the upper frame 33, the switch 94 provided on the upper frame 33 is activated. It is pushed by the detection bin 78 and automatically detects that the image forming cartridge 1 is unused. This detection signal is sent to the control system of the printer 31 to start counting the number of prints using the image forming cartridge 1 and to issue a restriction or warning against use of more than a predetermined number of prints based on this count. Conversely, if the image forming cartridge 1 to be installed has already been used, the detection bin 78 is retracted toward the waste toner casing 3 side. Therefore, even if the image forming cartridge 1 is attached to the upper frame 33, the switch 94 cannot be pressed. Therefore, unused waste toner casing 3
No action will be taken as would be the case if the

However, the usage status can also be detected at the necessary time. For example, by detecting the point in time when a predetermined number of sheets, such as 500 sheets, have been used and using this as a use start signal, it is possible to support test use of up to 500 sheets. Furthermore, the point in time when the image forming cartridge 1 has been used for printing the maximum number of sheets can be detected and a warning can be issued against further use.

In the above embodiment, when the erase means 45 is attached to the image forming cartridge 1, it is connected to the electrodes provided on the image forming cartridge 1 and a driving current is supplied. It may be electrically connected to 33. In that case, when taking out the image forming cartridge 1 for replacement etc., the image forming cartridge 1
After pulling out the image forming cartridge 1 from the upper frame 33, the erase means 45 can be pulled out from the image forming cartridge 1. Furthermore, at that time, it is preferable to provide cleaning means such as felt on the side surface of the image forming cartridge 1 so that the light projection surface can be cleaned by pulling out the erase means 45.

Effects of the Invention According to the present invention, since the erase means is disposed within the image forming cartridge, this erase means can be disposed close to the image carrier, and as a result, image creation using the image forming cartridge is possible. LE as an erase means in the device
It is possible to use a light source such as a D-array, which is more compact and inexpensive than when using a conventional halogen lamp, consumes less power, and has a small amount of heat, making it more suitable for laser light sources, etc. It has great effects, such as eliminating the need for heat countermeasures.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an image forming cartridge and a transfer charger section in a printer according to an embodiment of the present invention, FIG. 2 is a front view showing a schematic configuration of a printer in which an image forming cartridge is installed, and FIG. FIG. 4 is a perspective view showing the developing roller section, FIG. 5 is an enlarged front view of a portion of the developing roller section, and FIG. 6 is a partially enlarged sectional view of the image forming cartridge unused detection mechanism. FIG. 3 is a cross-sectional view of a portion of the waste toner casing shown in FIG. Image forming cartridge Developer casing Waste toner casing Photosensitive drum Cleaning plate Erasing means Charger.

Claims (1)

[Claims] (1) An image forming cartridge, which is an integral combination of an image bearing member, a developing means, a means for cleaning the image bearing member after transfer, and a charging means, is removably attached to the main body of the apparatus. An image forming apparatus characterized in that an erase means for removing electric charges remaining on an image carrier before charging is disposed in an image forming cartridge.