JPH02253289A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is applicable to electrostatic charging (including static elimination) of repeatedly used image bearing members such as photoreceptors and dielectric materials such as electrophotography and electrostatic recording. A name related to image forming devices such as copying devices, recording devices (printers), and display devices that form images by applying a series of image forming processes.

More specifically, among a series of image forming process equipment, at least an image bearing member and a corona charger for charging the surface of the image bearing member are collectively configured as a process cartridge that is detachable from the main body of the image forming apparatus. The present invention relates to a forming device.

(Prior Art) Image forming apparatuses with removable process cartridges are often employed as configurations of simple and compact image forming apparatuses such as personal types.

For example, when it comes to copying devices and printers that use transfer type electrophotography, generally a photosensitive drum as an image carrier,
A corona charger that uniformly charges the drum surface, a developer that develops the latent image formed on the drum surface, a cleaning device that cleans the drum surface after transfer, etc. are all installed in the main body of the device. The process cartridge has a structure that can be easily attached and detached even by an amateur, and the process cartridge that is attached and detached from the main body of the device has reached its durability (life of repeated use of the photosensitive drum, use up of the developer stored in the developing unit, etc.). By replacing the cartridge with a new one, you can make the image forming apparatus maintenance-free and improve serviceability. By exchanging several types of process cartridges with different developing colors, you can change the color of the output image (
It has the advantage that it is also possible to form color printing) and multicolor composite images (multicolor printing).

FIG. 6 shows a schematic configuration of a laser beam printer as a specific example of an image forming apparatus using a process cartridge attachment/detachment type.

Reference numeral 1 denotes a device exterior cylinder, and 2 a photosensitive drum as an image carrier, which is driven to rotate at a predetermined circumferential speed in the clockwise direction as indicated by the arrow. Negative charging, laser beam scanning exposure of target image information by a laser beam scanner 5, and development (reversal development) by a developing device 6 are performed to sequentially form toner images of the target image on the drum surface.

Transfer sheet material P is fed into the device for one sheet by the paper feed roller 15 from the side paper cassette 14, and the registration roller pair 1
At step 6, the photosensitive drum 2 is synchronized with the rotation of the photosensitive drum 2, and is conveyed to a transfer section between the tram 2 and the transfer device 7, and the toner images on the drum 2 side are sequentially transferred onto the surface of this conveyed sheet material 2.

The sheet 4p that has passed through the transfer section and has the toner image transferred thereto is separated from the drum 2 surface, is introduced into the fixing device 11 by the conveyor 10, where the image is fixed, and is printed onto the paper output tray 13 outside the apparatus by the output roller 12. It is output as a physical object.

After the toner image has been transferred, the second surface of the drum is cleaned by cleaning H8 to remove residual toner and other adhered contaminants, and eraser lamp 9 is applied.
After the electrical residual memory is erased by pre-exposure processing (full-surface light irradiation), it is used repeatedly for image formation. 5a
is a mirror that reflects the output laser from the laser beam scanner 5 toward the two surfaces of the photosensitive drum.

In the case of the apparatus of this example, four process devices, a photosensitive drum 2, a corona charger 3, a developing device 6, and a cleaning device 8, are configured as a process cartridge 20. The device is opened and removed by an appropriate device opening/closing method such as a device front door opening method or a device top half-opening method, and is attached to or removed from a predetermined position within the device body. When the cartridge 20 is properly installed in the apparatus main body, the equipment inside the cartridge 20 and the apparatus main body are mechanically and electrically coupled to become ready for image formation.

21 is an exterior housing (cartridge frame) of the cartridge, and the devices 2, 3, 6, and 8 are assembled and built into the housing 21 in a predetermined arrangement relationship. Reference numerals 22 and 23 denote an exposure opening (laser beam incidence opening) and a haze light opening (eraser light incidence opening) which are opened at predetermined positions on the top surface of the cartridge housing 21, respectively.

A corona charger 3 is generally used as a charging device for an image bearing member because of its good uniform charging performance.

However, one of the problems is the occurrence of image deletion and image blurring due to the generation of ozone products accompanying corona discharge. That is, ozone products (03°NOx, etc.) generated by the corona charger 3 react with talc (magnesium compound), etc., which is a component of paper powder, and become a conductive substance.
Ozone products adhere to the surface of the image carrier or react with the surface layer of the image carrier, making the surface of the image carrier locally or entirely conductive, thereby reducing charge retention.

In particular, a process cartridge 20 is constructed by including at least the image carrier 2 and a corona charger 3 as a charging means for charging the image carrier, and is used by being attached to and detached from the main body of the image forming apparatus. In the case of the image forming apparatus configured as above, the process equipment on the cartridge side including the corona charger 3 is hermetically housed in the cartridge housing 21, so that the air flow (air Ozone products tend to remain at a high concentration in the inner and outer peripheral parts of the charger 3 and in the cartridge, and the above-mentioned image deletion and image blurring become particularly problematic.

Therefore, conventionally, the exposure opening 22 of the cartridge housing 21 was used as an air intake port, and the pre-exposure opening 23 was used as an air vent.
→ inside the housing 21 → the opposing gap between the photosensitive drum 2 and the charger 3 → the pre-exposure space 23 → the outside of the housing 21. By actively exhausting the ozone product-containing air particularly generated in and around the charger 3 and the air inside the housing 21 to the outside, harmful effects such as image deletion and image blur caused by corona products are prevented. I try to do that.

(Problems to be Solved by the Invention) However, since there is a fan for air suction on the device main body side, it is difficult to effectively draw air only from the cartridge. In particular, a cartridge equipped with a plurality of corona chargers, for example, as shown in FIG. In the cartridge 20A for multiple development in which 62 is arranged and two-color printing is performed in one transfer (one-bath two-color system), the first developing device is disposed between the primary charger 31 and the secondary charger 32. 61, when drawing air in the circumferential direction of the photosensitive tram 21 as in the case of FIG. 6, it obstructs the air flow, making it impossible to remove ozone products around the secondary charger 3□, resulting in blurred images.・This was causing image smearing.

An object of the present invention is to eliminate the occurrence of image deletion and image blurring by devising a method to effectively remove corona products from within the cartridge.

(Means for Solving the Problems) The present invention provides at least an image bearing member and a corona charger among a series of image forming process equipment including an image bearing member and a corona charger as a charging process equipment for the image bearing member. In an image forming apparatus that combines these components into a process cartridge that can be freely attached to and removed from the image forming apparatus main body, the above process cartridge has an opening for ventilation inside the cartridge in its exterior housing, and On the side, when the process cartridge is attached to the main body of the apparatus, an air suction or blower is provided to suck the air inside the cartridge or blow it into the cartridge, corresponding to the ventilation opening on the process cartridge side. The ventilation opening on the process cartridge side and the corresponding air suction or blowing opening on the apparatus main body side support the image in at least the corona charger portion inside the process cartridge by air suction or blowing. This image forming apparatus is characterized in that it is provided with a relational structure that generates an air flow along the longitudinal direction of the part facing the body.

The present invention also provides a relationship in which, in the image forming apparatus described above, when the process cartridge has a plurality of corona chargers, an air flow is generated along the longitudinal direction of the portion facing the image carrier at least in each corona charger portion. The structure is characterized in that an opening for ventilation inside the cartridge and an opening for air suction or ventilation are provided in correspondence with the exterior housing side of the process cartridge and the apparatus main body side.
It is an image forming device.

(Function) That is, at least in the corona charger portion of the cartridge, air is drawn by a related structure that generates an air flow along the longitudinal direction of the portion facing the image carrier. By drawing air in the axial direction of the photosensitive tram 2 in the charger portion, corona products generated by the corona charger are always smoothly and efficiently discharged out of the cartridge by riding on the air flow. Even in the case of a cartridge having a plurality of corona chargers, the corona products generated in each corona charger can be discharged by drawing air with the above-mentioned air flow at least in each corona charger section. Always done smoothly and effectively. Therefore, the occurrence of image deletion and image blurring caused by the retention and concentration increase of corona products in the corona charger portion or inside the cartridge can be effectively prevented for a long period of time.

(Example) Example! (Figs. 1 to 5) Fig. 1 is a vertical sectional side view of the main part of an embodiment of the device according to the present invention, Fig. 2 is a partially cutaway plan view of the main part, and Fig. 3 is the end of the corona charger. FIG. 4 is an external perspective view of the process cartridge. Components and portions common to those of the device shown in FIG. 6 described above are given the same reference numerals and will not be described again.

Reference numerals 24 and 25 are an intake opening and an exhaust opening provided in the right end face plate 211 and left end face plate 212 of the cartridge housing 21, respectively. These openings 24 and 25 are provided at end plate surface positions corresponding to the right and left end positions of the corona charger 3 in the cartridge 20, respectively.

The corona charger 3 includes a horizontally elongated shield electrode 3a having a downward U-shaped cross section, and a discharge wire 3b stretched in the left-right direction inside the U-shaped shield electrode. As shown in FIG. 3, hollow open openings 3c and 3d of the U-shaped shield electrode 3a are provided on the IEi terminal blood and left end surface of the corona-charged H3, respectively.
The openings 3c and 3d are located at the joint end face plate 21. of the cartridge housing 21, respectively. and left end face plate 21
The air intake opening 24 and the non-air opening 25 of the air intake opening 2 correspond to each other and communicate with each other. The downward opening of the U-shaped shield electrode 3a is a discharge opening, which approaches the photosensitive drum 2 and faces the photosensitive drum 2.

34 is a ventilation opening provided on the right chassis plate 11 on the image forming apparatus main body side, 36 is an exhaust fan provided on the left chassis plate 12 on the apparatus main body side, and 35 is an intake opening provided in communication with the exhaust fan. It is.

When the process cartridge 20 is properly installed in the main body of the image forming apparatus according to a predetermined procedure, the cartridge 20
The intake opening 24 and the exhaust opening 25 on the side correspond to and communicate with the ventilation opening 34 and the intake opening 35 on the device main body side, respectively. In this case, a backing member (meshing material) 34, such as maltbrain rubber, is used so that the openings 24 and 34 and the openings 25 and 35 are in airtight communication with each other without air leakage at the joints.
351 may be provided in the openings 34 and 35 on the apparatus main body side or the openings 24 and 25 on the cartridge 20 side by adhesion or the like in advance.

In addition, a shutter member is provided in the openings 24 and 25 on the cartridge 20 side, and the shutter members keep the openings 24 and 25 closed when the cartridge 20 is taken out of the main body of the apparatus and stored. Therefore, opening 2
It is desirable that the force from 4.25 be inserted into the cartridge to block external light and prevent foreign matter such as dust from entering, and to open when the cartridge 20 is installed in the apparatus main body.

In this embodiment of the apparatus, the exhaust fan 36 uses approximately half of its intake surface as a dedicated intake surface for the intake opening 35, and the remaining intake surface serves as an exhaust surface for discharging hot air generated from the heat fixing device 11 to the outside of the apparatus. This is the configuration to be used as.

As a result, the operation of the exhaust fan 36 causes air to flow through ■ an outside air intake port (not shown) provided at a suitable location in the device body, ■ inside the device body, and ■
Air blowing opening 34 on the device main body side, ■ Intake opening 24 on the cartridge 20 side, ■ Opening 3C1 on the right end side of the corona charger 3, ■ Inner space of the shield electrode 3a of the charger 3, ■ Left end of the charger 3 Routes of the surface side opening 3d, ■ the exhaust opening 25 of the cartridge 20, ■ the intake opening 35 on the device main body side, the [phase] exhaust fan 36, and ■ the exhaust port (not shown) provided at a suitable location on the device main body. Air flow A occurs.

Also, outside air intake of the device body → inside the device body → exhaust fan 36
→ Air flow B is also generated inside the apparatus body outside the process cartridge 20 through the exhaust port. The air flow A passing through the inner space of the shield electrode 3a of the charger 3 in the cartridge 20 is caused by the air flow A passing through the inner space of the shield electrode 3a of the charger 3 in the cartridge 20.
The air duct functions as a straight air duct extending in a straight line from the left end side to the exhaust opening 25 side, and in the longitudinal direction of the portion facing the photosensitive drum 2 serving as the image carrier in the corona charger portion (the axial direction of the photosensitive drum l, This results in a smooth air flow along the drum generatrix direction).

Therefore, as charging is performed, the shield electricity of the charger 3 iH
Corona products generated in and around the cartridge 3a are always smoothly and efficiently discharged to the outside of the cartridge 20 along the air flow A described above.

As mentioned above, the left and right horizontally elongated shield electrodes of the charger 3, which have a U-shaped cross section, function as a straight air duct from the intake opening 24 side to the exhaust opening 25 side, so that the air flow is A.
By reducing the suction resistance and increasing the air flow rate, ozone products generated in and around the charger can be intensively and quickly exhausted and removed. and 1 on the exhaust side as the fan 36.
A sufficient amount of airflow can be obtained even with just one, and this configuration is particularly effective and suitable for small-sized image forming apparatuses such as small-sized laser beam printers. However, it is also possible to provide a fan on the intake side to obtain an even larger air volume.

The fan may be of an axial flow type, a cross flow type, or any other appropriate type, but it is desirable that the fan has both a large static pressure and a large air volume, that is, one that can secure a sufficient air volume even if the suction resistance is large.

In addition, the air flow B generated within the apparatus by the operation of the fan 36 exhausts and ventilates hot air within the apparatus.

Printing was actually performed using a reversal phenomenon laser beam printer having the same device configuration as that of this example.

Photosensitive tram 2 rollers 0φ OPC drum Printing speed: 8 sheets per minute of A4 size output Total current of corona charger = 500 μA Environment: Room temperature 30° C., humidity 80% The relationship between the main body fan air volume and the occurrence of image deletion was investigated. The results are shown in FIG. (2) is a case of a device according to the present invention, in which the shield electricity 8i3a of the charger 3 functions as an air duct to improve the efficiency of air flow within the cartridge, and (2) is a case of a device in which this is not the case. As is clear from the comparison between ■ and ■, there is a big difference in the likelihood of image blurring even with the same main body fan air volume. The reason for this is that the main body fan air volume in Figure 5 is 0.8m37a.
Looking at the case of +in, the number of washed out images is 4,000 and 1,500 in case of ■ and case of ■, respectively, but at this time, the wind speed around the primary charger in the cartridge is 5.0/ sec, 2.0/sec, which was a huge difference. In other words, airflow openings are provided on the cartridge side and the main body side to improve adhesion, and by drawing air in the direction of the drum axis, the wind speed inside the cartridge is increased and the airflow is improved. As a result of the above, it has become possible to form images without image deletion or image blurring.

Example 2 (Figures 7 to 11) This example is an example in which the present invention is applied to a two-color laser beam printer using the one-bath two-color system multiple development cartridge 20A shown in Figure 7. .

To explain the printing process of this two-color laser beam printer, the surface of the OPC photosensitive tram 2 is
After being uniformly negatively charged by , it is subjected to a first exposure L1. At this time, the surface of the photosensitive drum 2 has a potential as shown in A) of FIG.

Thereafter, the image is developed by the first developing device 61, and the secondary charger 3
2, it is charged negatively again. At this time, the surface of the photosensitive tram 2 has a potential as shown in B) in FIG. Thereafter, a second exposure 2 is performed to obtain a potential as shown in FIG. However, the developer at this time is the first developer 6. A developer of a different color from that of the developer is used.

Thereafter, after printing is performed on the transfer material by the transfer charger 7, the transfer residual toner remaining on the photosensitive drum 2 is stored in the cleaner 8.

At this time, the primary charger 3. Ozone products generated by the secondary charger 32 cause image deletion and image blurring, and must be promptly removed. but,
Primary charger 31 and secondary charger 3. During this period, the first developing device 6
1, it is difficult to draw a sufficient amount of air in the circumferential direction of the photosensitive drum 2 to prevent image blurring and image deletion.

Therefore, in this embodiment, the primary charger 3. and the secondary charger 32, as in the case of the device of Embodiment 1, the cartridge side has an intake opening 24, an exhaust opening 25, etc., and the device main body side has an air blowing opening 34 that communicates with them. An air intake opening [1 part 35, etc.] was provided to create an air flow in the space within the shield electrode of each charger 3I3□. FIG. 9 is a perspective view of a cartridge 20A provided with an intake opening 24 and an exhaust opening 25 for the primary charger 3I and the secondary charger 32, respectively.

Actually, in a reversal development two-color laser beam printer using a 60φ OPC drum as a photoconductor and a process speed of 50 mm/sec, the total current of the primary, secondary Ti, containers 3, and 32 was set to 400 μA, and air flowed to the side of the cartridge. An opening was provided for printing on 44-plate paper.

At this time, the potential in FIG. 6 is VDI=-50, respectively.
The drum direction currents of the primary and secondary chargers 3I and 32 were set so that VD2 = -800V, and negative toner was used for both the first phenomenon and the second phenomenon. The environment was a room temperature of 30° C. and a humidity of 80%.

FIG. 10 shows the relationship between the air volume of the main body fan and the occurrence of image deletion at this time. In Figure 10.

The relationship between the air volume of the main body fan and image blurring/image deletion when airflow is performed in the circumferential direction of the drum is also shown. From the figure, it can be seen that when air is drawn in the circumferential direction of the drum, image blurring and flow occur when the number of sheets printed is 500 or less, regardless of the air volume of the main body fan. Compared to that,
As shown in Figure 9, if an opening is provided, facing the opening on the main body side, and forming an air duct so that the air passage is in a straight line, drawing air in the direction of the drum axis, the air volume of the main body fan will be increased. As you can see, image blur and image blurring are less likely to occur.

The reason for this can be seen by looking at the relationship between the main body fan Mm and the air volume near the secondary charger in FIG. 11. Figure 11 shows that when an air duct is formed by the corona charger and the drum and air is drawn in the direction of the drum axis, the air volume near the secondary charger increases as the air volume of the main body fan increases, resulting in sufficient air flow. However, when air is drawn in the circumferential direction of the drum, the wind rL near the secondary charger is always low, so there is not much air flow, and ozone products tend to accumulate. I understand that.

Below 1- An air duct is formed by the corona charger and the photosensitive drum, and the opening on the side of the cartridge and the main body side are brought into close contact with each other, and the air is sent in the ring direction of the photosensitive drum. Blurring and image blurring can be made less likely to occur.

(Effects of the Invention) The present invention makes it possible to achieve good air flow, especially in multi-color, multi-development printers that have multiple corona chargers in the cartridge, and to print without blurring or blurring of images. became.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of the essential parts of an embodiment of the device according to the present invention, FIG. 2 is a partially cutaway plan view thereof, FIG. 3 is a perspective view of one end side of the corona charger, and FIG. 4 is a process diagram. A perspective view of one end of the cartridge, Figure 5 shows the main body fan air volume and image flow.
A graph showing the relationship between the number of sheets where blurring starts to occur, Fig. 6 is a schematic diagram of a conventional device, Fig. 7 is a schematic diagram of an l-bus two-color printer, Fig. 8 is an explanatory diagram of its printing process, and Fig. 9
The figure is a perspective view of the process cartridge of the printer.
Figure 0 is a graph of the relationship between the main unit fan and the occurrence of image blur, No. 11
The figure is a graph showing the relationship between the main body fan and the air volume near the secondary charger. 2 is a photosensitive drum as an image carrier, 3.3.32 is a corona charger, 6.61.62 is a developing device, 7 is a transfer charger, 8 is a cleaning device, 2o.20A is a process cartridge, 24. 25, 34, 35, 3c, and 3d are air flow openings, and 36 is the main body fan. Patent applicant: Canon Co., Ltd.

Claims (2)

[Claims] (1) Out of a series of image forming process equipment including an image bearing member and a corona charger as a charging process equipment for the image bearing member, at least the image bearing member and the corona charger are integrated into an image forming apparatus. In an image forming apparatus having a process cartridge that can be freely attached to and removed from the main body, the above process cartridge has an opening for ventilation inside the cartridge in its outer housing, and the process cartridge is mounted on the side of the image forming apparatus main body. It has an air suction or blowing opening that sucks air in the cartridge or blows air into the cartridge in correspondence with the ventilation opening on the process cartridge side in the installed state, and The ventilation opening and the corresponding air suction or blowing opening on the device main body side are used to suck or blow air to draw air along the longitudinal direction of the portion facing the image carrier at least in the corona charger portion of the process cartridge. An image forming apparatus characterized in that the image forming apparatus is provided in a relational configuration that causes a flow. (2) When the process cartridge has a plurality of corona chargers, the exterior housing of the process cartridge has a related structure that generates an air flow along the longitudinal direction of the portion facing the image carrier at least in each corona charger portion. 2. The image forming apparatus according to claim 1, further comprising an in-cartridge ventilation opening and an air suction or blowing opening in correspondence with the cartridge side and the apparatus main body side.