JP4620978B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic process.

  Conventionally, in an electrophotographic or electrostatic recording type image forming apparatus, a corona charger has been used as a charging means for an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric. In recent years, since it has advantages such as low ozone, low power, etc., it is a contact charging device, that is, a device that charges a charged body by contacting a charging member that applies a voltage to the charged body as described above. Has been put into practical use. In particular, a roller charging apparatus using a conductive roller as a charging member is preferably used from the viewpoint of stabilization of charging.

  In a roller charging type contact charging device, a conductive elastic roller as a charging member is brought into pressure contact with a member to be charged, and a voltage is applied thereto to charge the member to be charged.

  Specifically, since charging is performed by discharging from a charging member to an object to be charged, charging is started by applying a voltage higher than a certain threshold voltage.

  As an example, in the case where the charging roller is pressed and brought into contact with an electrophotographic OPC photosensitive member having a thickness of 15 μm as a member to be charged, the charging roller is about −560V. When a voltage is applied, the surface potential of the photoconductor starts to rise, and thereafter, the photoconductor surface potential increases linearly with a slope with respect to the applied voltage. Hereinafter, this threshold voltage is defined as the charging start voltage Vth. That is, in order to obtain the photoreceptor surface potential VD required for electrophotography, it is necessary to apply a DC voltage of charging potential: Vth + VD to the charging roller. A contact charging method in which only the DC voltage is applied to the contact charging member to charge the object to be charged is called a DC charging method.

  However, when this DC charging is performed, particularly in a high-humidity environment, “horizontal streaks generated in a halftone image” mainly caused by disturbance of the potential on the photosensitive drum before the charging step, An image defect called “drum positive ghost” caused by the difference in the upper charging potential occurs, which becomes a problem.

  In order to prevent such image detrimental effects (horizontal streaks and drum positive ghosts that occur in halftone images, etc.), a so-called neutralization unit is provided that neutralizes the residual potential by irradiating the photosensitive drum with light before the charging step. Is known to be effective.

  FIG. 8 shows an image forming apparatus equipped with a conventional static eliminator. In FIG. 8, a photosensitive drum 101 is uniformly charged by a charging roller 102, and then laser light modulated in accordance with an image signal from a scanner unit 103 including a laser, a polygon mirror, and a lens system is scanned and returned. Reflected by the mirror 104 and irradiated with laser light on the surface, an electrostatic latent image is formed. The electrostatic latent image formed by the laser light irradiation is developed as a toner image by the toner 106 in the developing device 105 to be visualized.

  On the other hand, the recording material 108 stored in the cassette 7107 is supplied to the registration roller 110 in synchronization with the formation of the latent image on the photosensitive drum 101 by the paper feed roller 109. The recording material 108 is conveyed to a transfer charger 111 including a transfer roller in synchronization with the leading edge of the latent image formed on the photosensitive drum 101 by the registration roller 110, and the toner image is transferred by the transfer charger 111. The recording material 108 is transferred. The recording material 108 onto which the toner image has been transferred is permanently fixed on the toner image by the fixing device 112 and then finally discharged outside the apparatus.

  The toner remaining on the photosensitive drum 101 is removed by a cleaning device 113 made of an elastic blade. The photosensitive drum 101, the charging roller 102, the developing device 105, and the cleaning device 113 are provided as a unitized process cartridge 100.

  Here, the generation mechanism of the horizontal white streak appearing one round after the photosensitive drum from the leading edge of the recording material, which is particularly noticeable as an image defect, will be described.

  FIG. 9 is an enlarged view of the vicinity of the nip between the photosensitive drum 101 and the transfer charger 111. Until the recording material p enters the transfer nip as in A, the potential on the photosensitive drum before the transfer is VD charged by the charging roller 102, and the potential on the photosensitive drum after the transfer nip is VD by the transfer current. It has fallen to lower Vtr.

  Next, when the leading edge of the recording material p enters the nip portion between the photosensitive drum 101 and the transfer charger 111 as shown in B, an air gap is formed in which the photosensitive drum and the transfer charger are not in contact with each other. In this part, since the surface of the photosensitive drum is hardly discharged by the transfer current, a part having a value of Vtr0 higher than Vtr is formed. Further, when the recording material advances through the transfer nip, the potential on the photosensitive drum after the transfer nip becomes Vtr again as indicated by C in the figure.

  The potential Vtr on the photosensitive drum returns to VD when charged by the charging roller 102 again. However, since the potential before Vtr is higher than Vtr at the portion Vtr0, the potential after charging is also increased. For this reason, when a halftone image or the like having a uniform density is printed after one round of the photosensitive drum in the portion before and after Vtr0, the potential of the portion corresponding to Vtr0 is high, resulting in a white stripe-like horizontal stripe image.

  As described above, the structure in which the transfer charger is in direct contact with the recording material has been described. However, when the transfer charger is a sponge roller having low hardness, the gap is small, and the hardness is higher on the transfer charger. When the resin belts overlap, the gap becomes large and horizontal white lines are likely to occur.

  As described above, in the contact charging device of the DC charging system, it is difficult to completely erase the potential history on the photosensitive drum after transfer, and therefore, a charge eliminating unit that irradiates light on the surface of the photosensitive drum after transfer becomes effective.

  As the above-described static elimination means, a configuration that can reduce the number of LEDs in a space-saving manner as disclosed in JP-A-2001-142365 has been proposed. Hereinafter, the structure of the static eliminating means of the above invention will be described. FIG. 10 is a schematic view of the image forming apparatus of FIG. 8 viewed from the X direction. The exterior portion of the image forming apparatus, the developing device 105 and the cleaning device 113 of the process cartridge 100 are not shown.

  As shown in FIG. 10, the static eliminator in this embodiment is equipped with an LED lamp 10 as a light source provided on the front side and the back side of the main body of the image forming apparatus and a process cartridge, and faces both the LED lamps 10. Thus, a light incident part is formed, and it is constituted by a rod-shaped light guide 11 as a light irradiating member that irradiates the guided light to the surface in the longitudinal direction of the photosensitive drum.

  As shown in FIG. 10, the LED lamp 10 is provided on the image forming apparatus side, and is disposed in an area outside the static elimination area on the photosensitive drum. Further, a light shielding member 12 that surrounds the outer periphery of the LED lamp 10 and shields light is provided so that light from the LED lamp 10 does not unnecessarily expose the end of the photosensitive drum 101.

  Next, the material, shape, function, and arrangement of the bar-shaped light guide 11 will be described. In the conventional form, this rod-shaped light guide 11 is largely equipped with the process cartridge 100. FIG. 11A shows its shape.

  The rod-shaped light guide 11 is composed of a light guide portion that transmits and reflects light, and a white resin case for improving reflection efficiency. As the material of the light guide, acrylic resin, polycarbonate, polystyrene, glass or the like having high light transmittance is used.

Further, as shown in FIG. 11A, the white resin case has “light incident portions” at both ends and “openings” having a predetermined width on the side surfaces, and the opening side is the photosensitive drum. 101 .

  FIG.11 (b) is the figure which looked at Fig.11 (a) from the Z direction. As can be seen from this figure, many V-shaped notches are made on the light guide surface opposite to the opening of the white resin case. The light incident from the light incident part of the bar-shaped light guide 11 is reflected by each V-shaped notch, changes its optical path, and is perpendicular to the longitudinal direction of the light guide from the opening of the white resin case. Irradiated.

  In other words, this light is irradiated as “static elimination light” on the surface of the photosensitive drum 101 with a predetermined static elimination width (see FIG. 10).

When a light guide is used as a light irradiating member to the photosensitive drum 101 as in the present embodiment, a light amount ripple on the photosensitive drum (as compared to a chip array type in which a plurality of LEDs are arranged as in the conventional example) (Swivel width) is also small, and uniform static elimination is possible.
JP 2001-142365 A

  In recent years, however, the multicolor image forming apparatus has been reduced in size and the photosensitive drum diameter of the process cartridge has been reduced. Therefore, it is necessary to secure a space for attaching a light guide around the photosensitive drum as in the past. Has become very difficult. Further, since the conventional static eliminator attaches the light guide to the process cartridge, it increases the cost of the process cartridge. Furthermore, although the light guide has no life, it was replaced with the life of the process cartridge, which was not desirable from the viewpoint of ecology. In particular, in the case of a multicolor image forming apparatus having a plurality of process cartridges, the user bears the cost of a large number of light guides that do not need to be replaced.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and an image forming apparatus and a process capable of easily and inexpensively obtaining image formation free from image defects such as horizontal stripes and drum positive ghost in a minimum space. The cartridge is to be provided.

  The present invention is an image forming apparatus having the following configuration.

A rotatable photosensitive member, a charging unit that charges the photosensitive member, an exposure unit that exposes the photosensitive member charged by the charging unit, and an electrostatic latent image formed on the photosensitive member by the exposing unit. an image forming apparatus comprising developing means you visualized as an image, a belt movable, and a transfer member forming a transfer nip with the photosensitive member via the belt, by rotation of the photosensitive member With respect to the direction of movement of the surface of the photoconductor, the directivity angle is reduced only from the end of the space in the direction of the rotation axis of the photoconductor to the space sandwiched between the belt and the photoconductor downstream of the transfer nip. a light source for irradiating light was, light irradiated from the previous SL light source, at least a part of the light is reflected by the belt, one end in the rotation axis direction of the photoreceptor surface of the photoreceptor From the other end In the image forming apparatus characterized by irradiating.

As described above, according to the present invention, there is no necessity to install the high cost of the apparatus so as to irradiate the photosensitive drum side by side a plurality of LED on the body side, also, by providing a light guide cartridges side cartridge It has become possible to achieve a static elimination exposure means that does not increase the cost of the above. Therefore, it is possible to provide an image forming apparatus that can easily reduce the size of the image forming apparatus and can prevent image adverse effects such as horizontal stripes and drum positive ghosts generated in a halftone image with a low-cost configuration.

  Examples of the present invention will be described below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto. Only the characteristic part of the invention will be mainly described.

  1 to 3 show the configuration of the first embodiment of the present invention.

  In this embodiment, a color image forming apparatus that is complicated and requires miniaturization will be described as an example. Color image forming apparatuses are divided into various systems. For example, in addition to the well-known multiple transfer system / intermediate transfer body system, a color image is superimposed on the surface of the photoconductor and then collectively transferred to form an image. There are a multiple development system, an inline system in which a plurality of different color image forming means (process stations) are arranged in series, and a developed image is transferred onto a transfer material conveyed by a transfer belt. Of these methods, the in-line method is excellent because it is possible to increase the speed and the number of times of image transfer is small, which is advantageous for image quality.

FIG. 1 shows an inline configuration. In FIG. 1, an electrostatic attraction transfer belt (hereinafter referred to as ETB: Electrostatic Transfer Belt) 1 as a belt-like transfer member is stretched by each of a driving roller 6, an attraction opposing roller 7, tension rollers 8 and 9, and is indicated by an arrow. Rotate in the direction. Process stations 201 (yellow), 202 (magenta), 203 (cyan), and 204 (black) of different colors are arranged in a row on the peripheral surface of the ETB 1, and the photoconductor in each process station is attached to the transfer roller 3. It arrange | positions facing and contact | abuts on the surface of ETB1 . Further, the suction roller 5 is disposed upstream of the process station and is in contact with the suction counter roller 7. Here, the transfer material p is biased when passing through the nip formed by the suction roller 5 and the suction counter roller 7 , is electrostatically attracted to the ETB 1, and is conveyed in the direction indicated by the arrow.

As ETB1, resin films such as PVdF, ETFE, polyimide, PET, polycarbonate, etc. having a thickness of 50 to 200 μm and volume resistivity of 10 ⁹ to 10 ¹⁶ Ωcm, or rubber having a thickness of about 0.5 to 2 mm, such as EPDM For example, a surface layer obtained by dispersing a fluororesin such as PTFE in urethane rubber is used as the surface layer. In particular, in this example, a belt having a thickness of 100 μm coated with an acrylic resin having a thickness of 1 μm was used as a belt for maintaining a high surface reflectance from the initial stage to after durability. This belt has a glossiness of 90 or more and has a very high reflectance. The gloss value of the belt is a value measured with a commercially available gloss meter (PG-3D manufactured by Nippon Denshoku).

  Here, the image forming process will be described.

  First, an image forming process in the process station will be described. The description is given using a yellow process station, but the same applies to other color stations.

FIG. 2 shows the configuration of the process station. A photosensitive drum 211 as a rotatable photosensitive member is uniformly charged by a charger 212 and is exposed by scanning light 214 from an exposure optical system 213 to form an electrostatic latent image. The electrostatic latent image is developed by a developing roller 215 as a developing unit, and a toner image is visualized on the photosensitive drum 211. Transfer residual toner remaining on the Rukoto no photosensitive drum 211 is transferred by the transfer process described later, the cleaning blade 217 as a cleaning means provided downstream of the transfer roller 3 with respect to the rotation direction of the photosensitive drum 211 And is removed from the photosensitive drum 211 and accommodated in a waste toner container 218.

  Next, the transfer process will be described.

  In a generally used reversal development method, when the photosensitive member is, for example, a negative-polarity OPC photosensitive member, a negative-polarity toner is used when developing the exposed portion. Accordingly, a positive transfer bias is applied to the transfer roller 3 from the bias power source 4.

  In the actual printing process, taking into account the moving speed of the ETB1 and the distance between the transfer positions of each process station, image formation at the process station is performed at the timing when the positions of the toner images of each color formed on the transfer material coincide. Transfer process Transfer material p is transported, and a toner image is completed on the transfer material while the transfer material p passes through the process stations 201 to 204 once. After the toner image is completed on the transfer material, the transfer material p is passed through a fixing device (not shown), and the toner image is fixed on the transfer material p.

In recent years, the diameter and interval of photosensitive drums have become very small in order to reduce the size and cost of multicolor image forming apparatuses. For this reason, the space for installing the static elimination exposure means for static elimination has been very limited. In FIG. 2, the LED 10 serving as a static elimination exposure unit is disposed downstream of the transfer roller 3 and upstream of the cleaning blade 217 with respect to the rotation direction of the photosensitive drum 211. Further, the LED 10 is provided on one end side in the rotation axis direction of the photosensitive drum 211, and a portion surrounded by the photosensitive drum 211, the transfer belt 1, the photosensitive drum shutter 216, and the process cartridge frame 219 is laterally arranged on the photosensitive drum 211. Although it is installed at an angle that directly irradiates light toward the image forming area, the distance between the transfer material p that is conveyed is actually too narrow, and a conventional light guide is used between the frame of the process cartridge and the transfer belt. It is very difficult to install in a sandwiched space. For this reason, in this embodiment, no light guide is provided, and the light of the LED is directly applied to the photosensitive drum.

FIG. 3 is a view of the vicinity of the process station of FIG. 2 as viewed obliquely. Here, the optical axis of the light emitted from the LED 10 is set parallel to the rotational axis of the photosensitive drum, and the light of the LED is projected onto an area (image forming area) after transfer on the photosensitive drum. When the light from the LED irradiates the surface of the photosensitive drum before transfer in an adjacent process station, it causes an image defect such as scattering of a line image. Therefore, in this embodiment, the process cartridge (second The shutter that covers the exposed surface of the photosensitive drum and removes the light when the cartridge is removed irradiates the photosensitive drum of the second cartridge with the LED light acting on the photosensitive drum of the adjacent process cartridge (first cartridge). Since it is a structure to block, it is not necessary to provide a special light blocking means. On the other hand, since an ETB having a very high gloss is used in this embodiment, the LED light is repeatedly reflected on the surface of the ETB and the photosensitive drum, particularly in a portion where white streaks occur at the front end of the paper. It is possible to effectively guide light to the end of the photosensitive drum opposite to the side.

As the characteristics of the LED, those having a peak wavelength in the photosensitive wavelength range of the photosensitive drum, a narrow directivity angle, and a high luminous intensity are desirable. In this example, Toshiba's TLRE20TP type was used. This LED has a peak wavelength of 630 nm, a directivity angle of 7 degrees, and a very high luminous intensity of 7000 mcd. Therefore, it is possible to satisfactorily irradiate the entire image forming area in the rotation axis direction of the photosensitive drum without providing a special light collecting means.

  Tables 1 to 3 show the results of measuring the potential on the photosensitive drum before and after exposure for each ETB glossiness in the image forming apparatus having the above configuration. The ETB in Table 1 is the type coated with the acrylic resin of this example, the ETB in Table 2 is the initial state of the belt without the acrylic coating, and the ETB in Table 3 is the belt without the acrylic coating on a 100,000 sheet print test. The surface state is roughened. In addition, when the acrylic resin was coated, the glossiness was maintained at 80 or more even when the printing test for 100,000 sheets was executed.

  Here, the potential (VD) on the photosensitive drum in the non-image area due to primary charging is −400 V, the transfer bias is not applied so that the VD is not neutralized by the transfer bias, and the potential on the photosensitive drum is as shown in FIG. The potential measurement probe 17 was placed at the development position, and the surface potential meter 18 was used for measurement. In particular, since it is difficult to measure the potential after static elimination exposure before primary charging, the potential on the photosensitive drum is measured at the development position after the primary charging is turned off.

  From the above results, the light of the LED is guided to the side opposite to the light source by the acrylic coating having a very high reflectance, and the potential left-right difference after static elimination becomes 100 V or less only by exposure from one side in the configuration of this example, It is possible to achieve an image forming apparatus in which there is no occurrence of defects such as white and horizontal stripes on the image, and no difference in density in the left and right direction of the image due to the memory effect of the photoconductor occurs even after, for example, about 1000 continuous sheets. I found out.

  In this embodiment, the optical axis of the LED is set parallel to the rotational axis of the photosensitive drum. However, for example, a small angle is set so that the optical axis of the LED intersects the photosensitive drum surface at the end opposite to the photosensitive drum. It is also effective to provide

  5 and 6 show the configuration of the second embodiment of the present invention. The following description will be made based on this figure. Components having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In general, when a commercially available LED in which an LED light emitter and a lens are packaged is used, the irradiation angle is about 7 degrees, so in order to narrow the angle further, it is necessary to separate the light emitter and the lens. There is. Therefore, this embodiment is characterized in that a small lens 15 is mounted on the front surface of the chip-like light emitter 10 as shown in FIG.

  In this embodiment, as shown in FIG. 6, a lens 15 having a focal length of 15 mm and a diameter of 10 mm is installed at a position 15 mm away from the LED illuminant 10 serving as a point light source, and the LED light is converted into parallel light. The photosensitive drum was irradiated. As the LED, TLRMH1100A manufactured by Toshiba was used. In the case of the chip type LED, the light amount is lower than that of the package type LED, and the light amount of the type of this embodiment is only 150 mcd. Therefore, in this embodiment, the LED and the lens are installed on the left and right sides of the photosensitive drum.

  Table 4 shows the surface potential of the photosensitive drum before and after static elimination in this example, as in Example 1.

  As is apparent from Table 4, when the configuration of this example is adopted, the surface potential after neutralization drops only to about 50 V at the minimum, but relatively uniform neutralization is possible with little difference between right and left. For this reason, the temperature / humidity conditions in which the apparatus is placed are very severe, for example, under severe conditions in which a plurality of colors are superimposed on a halftone image in which unevenness is very conspicuous, the configuration of Example 1 is on the opposite side to the static elimination light source. Even under the condition that a minute white streak image can be seen, the configuration of the present embodiment makes it possible to make the white streak completely invisible.

  In general, increasing the number of LEDs increases the cost, but chip-type LEDs are less expensive than package-type LEDs, and the lens can be lowered by using plastic lenses with lower accuracy. The cost can be kept lower than using a conventional LED array or mounting a light guide on the cartridge.

  Further, as in the first embodiment, since it is not necessary to attach a light guide to the cartridge, there is a margin in the space around the photosensitive drum, and the apparatus can be downsized.

  This arrangement of LEDs on both sides is very effective in reducing the left / right difference, and is particularly useful for machines with a wide longitudinal width such as the A3 machine, such as when using LEDs with a large amount of light as in Example 1. It becomes.

  FIG. 7 shows the configuration of the third embodiment of the present invention. The following description will be made with reference to this figure. Components having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As in the first embodiment, the present embodiment is characterized in that the LED 10 is provided only on one side, and the reflection plate 13 that reflects the LED light is provided on the side of the photosensitive drum opposite to the LED. In the present embodiment, the reflector plate was placed on a main body side plate (not shown) by attaching an aluminum tape to a resin mold support plate. However, the support plate can be anywhere as long as it does not interfere with the process cartridge attaching / detaching operation and does not interfere with the ETB attaching / detaching operation, and aluminum tape is less expensive than optical parts such as light guides. It is also possible to attach the cartridge parts to the process cartridge by extending the cartridge parts and using them as support plates, or to extend and attach the ETB frame.

For example, when a reflector is attached to the process cartridge, replace the reflector with the process cartridge that can be attached to and detached from the main body of the device before the reflectance of the reflector decreases due to adhesion of a small amount of scattered toner. There is an advantage that it becomes possible to do. Also, by integrating the reflector with the process cartridge, there is no need to provide a space for guiding the reflected light in the process cartridge, and there is an advantage that the risk of light leakage and the user touching the surface of the photoreceptor is reduced.

  On the other hand, when the reflector is attached to the ETB frame, it is possible to cover the reflector so that the reflector is not moved away from the process cartridge or the scattered toner does not fall on the reflector.

  As for the installation angle of the reflector, in order to irradiate the end of the photosensitive drum opposite to the LED where the light coming from the LED is particularly weak, the upper end of the reflector may be inclined toward the LED with respect to the normal of the surface of the photosensitive drum. desirable. Conversely, if the tilt angle is too large, only the end portion close to the reflector is irradiated, so the optimum tilt angle with respect to the normal is 10 ° or less.

  With the configuration as described above, the LED side of the photosensitive drum surface is neutralized by the light L-LED from the LED and the reflector side is neutralized by the light L-Mirror from the reflector as shown by the light flux in FIG. Things are possible.

  Table 5 shows the surface potential of the photosensitive drum before and after static elimination in this example, as in Examples 1 and 2.

  As apparent from Table 5, when the configuration of the present embodiment is adopted, the potential on the side opposite to the LED can be lowered to a potential having a sufficient margin as compared with the first embodiment. Therefore, as in the second embodiment, even in a corner case with extremely severe conditions, it is possible to make white stripes completely invisible by adopting the configuration of this embodiment. Further, in the configuration of this embodiment, there is one LED, and the static elimination light can be made uniform by a very low cost member such as a reflective tape, so that the static elimination means can be mounted without increasing the cost of the image forming apparatus. became.

  In this embodiment, aluminum tape is used as the reflecting member. However, various other types of reflectors such as a sheet metal of a frame or an extended metal contact are used without limitation to the configuration of this embodiment. It is possible to take a configuration.

1 is a diagram illustrating an image forming apparatus according to a first embodiment of the present invention. The figure explaining the process cartridge vicinity which concerns on 1st Example of this invention The figure explaining the process cartridge vicinity which concerns on 1st Example of this invention The figure explaining the electrical potential measurement concerning 1st Example of this invention The figure explaining the structure which has the lens which concerns on 2nd Example of this invention. The figure explaining the structure which has LED in the both sides based on 2nd Example of this invention The figure explaining the structure which has a reflecting plate which concerns on the 3rd Example of this invention. Mechanical structure of the conventional example of the present invention The figure explaining the prior art example of this invention The figure explaining the light guide concerning the prior art example of this invention The figure explaining the light guide concerning the prior art example of this invention

Explanation of symbols

1 ETB (electrostatic transfer belt)
201-204 Process station 3 Transfer roller 4.16 Bias power supply 5. Adsorption roller 6. Drive roller 7. Adsorption counter roller 8..9 Tension roller 10.
DESCRIPTION OF SYMBOLS 11 Light guide 12 Light-shielding member 14 Cleaning member 15 Lens 17 Potential measurement probe 18 Surface potential meter 100 Process cartridge 101 Photosensitive drum 102 Charging roller 103 Scanner unit 104 Folding mirror 105 Developing device 106 Toner 107 Cassette 108 Recording material 109 Paper feeding roller 110 Resist Roller 111 Transfer charging device 112 Fixing device 113 Cleaning device
211,221,231,241 Photosensitive drums of the first, second, third and fourth process stations
212, 222, 232, 242 Charger of 1st, 2nd, 3rd, 4th process station
213, 223, 233, 243 First, second, third and fourth exposure station exposure optical systems
214, 224, 234, 244 Scanning light of first, second, third and fourth process stations
215, 225, 235, 245 First, second, third and fourth process station developing rollers
216, 226, 236, 246 Photosensitive drum shutters of the first, second, third and fourth process stations
217,227,237,247 Cleaning blades for the first, second, third and fourth process stations
218,228,238,248 Waste toner containers for the first, second, third and fourth process stations
219,229,239,249 First, second, third and fourth process station frame

Claims (9)

A rotatable photoreceptor,
Charging means for charging the photoreceptor;
Exposure means for exposing the photoreceptor charged by the charging means;
A developing unit you the electrostatic latent image formed on the photosensitive member by the exposure means as a toner image,
A movable belt,
A transfer member that forms a transfer nip with the photoreceptor via the belt;
An image forming apparatus comprising:
With respect to the movement direction of the surface of the photoconductor due to the rotation of the photoconductor, the space between the belt and the photoconductor is downstream of the transfer nip, and only from the end of the space in the rotation axis direction of the photoconductor. , With a light source that emits light with a narrowed directivity angle,
The light emitted from the front Symbol source, at least a part of the light is reflected by the belt, that is irradiated from one end to the other end in the rotation axis direction of the photoreceptor surface of the photoreceptor An image forming apparatus. A cartridge having another photoconductor that contacts the belt downstream of the photoconductor in the moving direction of the belt is removable.
The cartridge includes a shutter member that covers the another photoconductor when the cartridge is detached from the image forming apparatus main body and exposes the other photoconductor when the cartridge is attached to the image forming apparatus main body. And
When the cartridge is mounted on the main body of the image forming apparatus, the shutter member is positioned between the photoconductor and the other photoconductor, and the light emitted from the light source is not irradiated to the other photoconductor. The image forming apparatus according to claim 1, wherein the image forming apparatus blocks light.   The image forming apparatus according to claim 1, wherein the light source is a light emitting member in which an LED light emitter and a lens are packaged, and a directivity angle of the light source is 7 ° or less. The image forming apparatus according to claim 3 , wherein a luminous intensity of the light source is 7000 mcd or more. Wherein the light source, and a lens for a light emitting luminous body of the chip-in LED with the said light emitter into parallel light, orientation angle of the light source is characterized in that it is 7 ° or less claim 1 or 2 the image forming apparatus according to. The image forming apparatus according to claim 5 , wherein a luminous intensity of the light source is 150 mcd or more. The light source irradiates light only from one end portion of the space in the rotation axis direction of the photoconductor, and includes a reflecting member that reflects light only at the other end portion in the rotation axis direction of the photoconductor. Item 7. The image forming apparatus according to any one of Items 1 to 6 . It said light source image forming apparatus according to any one of claims 1 to 6, characterized in that light is irradiated from both end portions in the rotation axis direction of the photosensitive member of the space.   The image forming apparatus according to claim 7, wherein the reflecting member is provided on a frame of the belt.

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