JP4801940B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus of an electrophotographic system using an organic photoreceptor having improved wear resistance of a photosensitive layer.

Conventionally, in an image forming apparatus using an electrophotographic system, it is known to form a latent image on an image carrier having a photosensitive layer such as OPC or a-Si (see, for example, Patent Documents 1 to 6). .
For the a-Si photoreceptor, a photoreceptor composed of a layer containing no Si, such as aC layer, aC: H layer or aC: H: F layer as a surface layer, or a- There is a photoreceptor constituted by a layer containing Si such as SiC: H or a-SiN: H.
In a photoreceptor composed of a layer containing Si, such as a-SiC: H or a-SiN: H, on the outermost layer, the discharge energy due to corona discharge during charging is reduced by Si-H, Si-Si, Si-C. Ozone acts on dangling bonds formed by breaking bonds such as low-resistance SiOx gradually.
On the other hand, NOx of the discharge product formed at the time of charging adheres to the surface of the photoconductor regardless of the configuration of the photoconductor, and lowers the resistance due to the influence of moisture in the atmosphere. NOx adhering to the aC: H layer or the aC: H: F layer can be recovered during the initial period, but is completely fixed by repeating the copying process, and the image flow is restored unless it is completely removed. Is impossible.
It is known that when image flow occurs on the photoconductor, it can be improved by heating or polishing the photoconductor according to the cause of the image flow. When a low-resistance corona product such as NOx adheres to the photosensitive layer, it can be improved by heating at a temperature of about 40 to 45 ° C., and can also be implemented with an OPC photoreceptor or Se photoreceptor having an overcoat layer.
However, in the case of a surface layer using Si such as a-SiC: H or a-SiN: H, a SiOx layer is formed on the surface of the photoreceptor for the above-described reason. When the SiOx layer is formed, the image flow is hardly improved by heating at about 40 to 45 ° C, and heating at about 50 to 55 ° C, which is 5 to 10 ° C higher, is required. Moreover, the image flow recurs as soon as the temperature drops.
Therefore, it is necessary to always maintain the temperature during image formation. Heating is also required during standby and when not in use. For this reason, today, environmental problems such as energy saving and resource saving are considered to be inconvenient.

On the other hand, since the organic photoreceptor is used while scraping the photosensitive layer, it is not affected by Nox, but its lifetime is several hundred K sheets, which is inferior to the a-Si photoreceptor. For this reason, attempts have been made to increase durability by providing a surface layer with wear resistance on the photosensitive layer.
Examples of the wear resistance improvement technique include those using a curable binder in the cross-linked charge transport layer disclosed in Patent Document 1, those using a polymer type charge transport material disclosed in Patent Document 2, and Patent Document 3 And the like, in which an inorganic filler is dispersed in the cross-linked charge transport layer disclosed in 1).
In such an OPC photoreceptor having improved wear resistance, a low-resistance corona product such as Nox adheres like an a-Si photoreceptor, and image flow occurs in a high humidity environment. The image flow in a high humidity environment can be solved by warming the photosensitive member, and since there is no formation of Si0x like a-Si, it is not necessary to maintain a normal temperature.
As a method of warming the photosensitive member, a method of mounting a planar heater inside the photosensitive element tube has been widely used, and a method of using a fixing device as a heat source (Patent Document 4), Have been proposed (Patent Documents 5 and 6).
In addition, in the case of a machine that generates a lot of ozone such as electrification (CH), the Nox component adhering to the casing and the like when it is stopped at night is gasified and falls onto the OPC photoconductor, reducing the resistance of the OPC outermost surface. Partial image flow may occur.
JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent Laid-Open No. 6-130771 JP-A-5-257359 JP-A-6-19246

However, in an organic photoconductor having abrasion resistance, even if the attached low-resistance material is removed by heating, image flow may occur due to various reasons.
In view of the above, the object of the present invention is to generate image flow even in an OPC photoconductor excellent in wear resistance by heating a portion facing the charging device / transfer device to 55 ° C. or higher. An object of the present invention is to provide an image forming apparatus that eliminates the problem.

In order to solve the above-described problems, an invention according to claim 1 is an electrophotographic image forming apparatus including an organic photoreceptor, a charging device, and a transfer device, and includes at least the charging device or the transfer device. Heating means for heating the portion of the organic photoreceptor facing the substrate, and control means for controlling the heating means. The heating means generates heat, and at least a portion of the organic photoreceptor facing the charging device or the transfer device is heated to 50 ° C. or higher .
According to a second aspect of the present invention, in the first aspect, the heating means heats the charging device on the upper side of the organic photoconductor or the upper portion of the organic photoconductor facing the transfer device. And
A third aspect of the invention is characterized in that, in the first or second aspect, the heating means blows warm air to the organic photoreceptor.
According to a fourth aspect of the present invention, in the first, second or third aspect, in addition to the heating means, there is provided another heating means for heating other than the organic photoconductor portion heated by the heating means, and the control means is It is characterized in that it is determined whether or not to heat by the other heating means according to the detection result of the environmental sensor.

  According to the present invention, the image forming apparatus can eliminate the occurrence of image flow even in OPC having excellent wear resistance by heating the OPC portion facing the charging device or the transfer device to 55 ° C. or more. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a flowchart for explaining the operation of the image forming apparatus according to the first embodiment shown in FIG.
In the first embodiment, the drum-shaped organic photoreceptor (hereinafter referred to as OPC) 1 is not shown, but on the support, at least from the charge generation layer, the charge transport layer, and the cross-linked charge transport layer. A photosensitive layer is provided.
The crosslinked charge transport layer is formed by curing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Yes. As a result, the wear resistance of the OPC 1 is greatly improved as compared with the prior art.
As the charging device 2, a double-wire scorotron with an opening width of 32 mm (circumferential direction) is used with a total current of 1,400 μA. A planar heater 7 using nichrome wire is provided inside the OPC 1 facing the charging device (CH) 2 so as to heat about 48 mm in the circumferential direction.
The transfer device 4 is disposed on the side facing the charging device 2 across the OPC 1, the developing device 3 is disposed on the right side of the drawing in the drawing, and the cleaning device 5 is disposed on the side facing the OPC 1 across the OPC 1. A neutralization device (QL) 6 is disposed between the charging device 2 and the cleaning device 5.
Each of the above components and other components are all controlled by a control means (CPU) (not shown).
Here, it compares with the conventional case where the heater of this Embodiment is not mounted | worn. About 20K sheets were passed through A4Y in a 10% environment at 20 ° C., and the image flow after being left overnight was compared. When the heater was not used, an image flow occurred in a portion corresponding to a position immediately below the charging device over a width of about 40 mm (in the OPC photosensitive member circumferential direction).
On the other hand, in the present embodiment, when the OPC 1 was stopped according to the flow of FIG. 2 and the portion corresponding to just below the CH was heated to about 55 ° C. and heated for about 3 minutes, no image flow was observed.

In FIG. 2, the power is turned on (S1), and it is determined whether or not 3 hours or more have passed since the exhaust fan (not shown) is stopped (S2). Control of the planar heater 7) is started (S3). It is determined whether 180 seconds have passed when the OPC temperature is 55 ° C. or higher (S4). If 180 seconds have passed, the drum heater is turned off.
The photosensitive member temperature is constantly monitored by an OPC temperature detecting means (not shown) when the heater is used, and the OPC heater (drum heater) is controlled according to the temperature detected by the OPC detecting means. .
As a result, no image flow occurs due to NOx adhering when left unattended and causing the reduction in resistance to be removed by heating.
In the configuration of the present embodiment, no image flow occurred regardless of the environmental conditions during the period when the paper was passed and left for about 4 hours after the fan stopped. Thus, in this embodiment, the OPC heater is used when 3 hours or more have elapsed after the fan stops.
In the present embodiment, the temperature is raised to 55 ° C. in order to obtain a more reliable effect, but it has been confirmed that the image flow becomes a level with no problem when heating at 50 ° C. or higher (described later). (See FIG. 7).
As described above, even when OPC having improved durability is used, the image flow can be prevented by heating the portion facing the charging device (CH) before the start of use. By heating the portion facing the charging device 2 on the upper side with respect to the photoconductor, the image flow can be prevented by heating the minimum necessary portion.

FIG. 3 is a schematic diagram showing the configuration of the second embodiment of the present invention in which the transfer separation device is on the upper side of the OPC and the charging device is on the lower side. In the image forming apparatus of FIG. 3, the transfer separation device 4 is arranged on the upper side of the OPC 1, and the charging device 2 is on the lower side.
The charging device 2 uses a scorotron, and the transfer separation device 4 uses a corotron. In the present embodiment, an OPC heating means (IH heater) 7 using an induction heating method is disposed on the upper surface of the OPC 1 and inside the photoconductor (OPC) 1 facing the transfer separation device 4.
Regarding the induction heating method, examples described in Japanese Patent Application Laid-Open Nos. 2001-242732 and 2001-13805 were used. By adopting the induction heating method, there is a merit that the temperature can be raised faster than the planar heater.
A transfer separation device 4 is disposed on the side facing the charging device 2 with the OPC 1 interposed therebetween, a developing device 3 is disposed on the right side of the drawing in the drawing, and a cleaning device 5 is disposed on the side facing the OPC 1 with the OPC 1 interposed therebetween. A static eliminator (QL) 6 is disposed between the charging device 2 and the cleaning device 5.
NOx that brings about a reduction in resistance is generated from both the charging device 2 and the transfer separation device 4 at the time of discharging. However, when the NOx component adhering to the casing (not shown) or the like is gasified when left untreated, Since the component falls in the direction of gravity, the portion of the OPC 1 facing the charging device 2 located below the OPC 1 is not affected by NOx even when left unattended.
Therefore, the occurrence of image flow can be prevented by heating only the portion facing the transfer separation device 4 and the like above the OPC 1 as in the present embodiment. That is, the image forming apparatus heats a portion facing the transfer separation device 4 on the upper side with respect to the photoreceptor (OPC) 1 and thereby heats a minimum necessary portion, thereby preventing image flow. .

FIG. 4 is a schematic diagram illustrating the configuration of the third embodiment of the present invention. FIG. 5 is a schematic perspective view for explaining the third embodiment of FIG. 4 and 5, a suction port (not shown) is provided on the right side when viewed from the front of the machine, and a dustproof filter 9 is attached to the suction port.
Sirocco fan (drum cooling fan) 10 takes in air from this suction port and blows it into the duct. There is a heating element 11 in the duct, and it is divided into two hands by the duct at the end.
In FIG. 4, the transfer device 4 is disposed on the side facing the charging device 2 with the OPC 1 interposed therebetween, the developing device 3 on the right side of the drawing and the cleaning device 5 on the side facing the OPC 1 with the OPC 1 interposed therebetween. Further, a static eliminator (QL) 6 is disposed between the charging device 2 and the cleaning device 5.
In the present embodiment, a PTC heater 11 that generates heat at 200 ° C. is used as a heating element. Actually, the PTC heater 11 is installed in a case (not shown) provided with a plurality of aluminum fins (not shown) as heat sinks. This heat radiating plate is installed in parallel with the direction of the wind and the fins so that the fins do not obstruct air blowing, and insulation from the PTC heater 11 is ensured.
One of the divided flow is blown into the OPC 1. A hole 1b is provided in the flange 1a of the OPC 1 so that air can pass therethrough. The other shunted air is blown to the surface of the photoreceptor through a duct having openings corresponding to the longitudinal direction of the photoreceptor and the entire image forming width.
In addition, a main body exhaust fan 13 is provided via a toner filter 12 for suction from the vicinity of the charging device 2 to the outside of the apparatus, and an ozone filter 14 is provided at the exhaust port. Further, in the present embodiment, a non-contact temperature sensor (not shown) of a radiant infrared detection system is used as a detecting means for detecting the temperature of the photosensitive member.

FIG. 6 is a flowchart for explaining the operation of the third embodiment. The power is turned on (S11), and it is determined whether or not 3 hours or more have elapsed after the main body exhaust fan 13 is stopped (S12). If 3 hours or more have elapsed, the diversion of warm air is stopped and the drum heater (PTC heater 11) is stopped. ) Is started (S13).
It is determined whether 180 seconds have elapsed when the temperature of the OPC1 is 55 ° C. or higher (S14). If 180 seconds have elapsed, it is determined whether the absolute temperature is 0.013 or higher (S15), and the hot air is diverted. Is started (S16). Next, it is determined whether or not 300 seconds have elapsed after the start of driving of the OPC 1 (S17).
In the present embodiment, the drum heater (PTC heater 11) is operated according to the flow of FIG. 6 described above as in the first embodiment. By heating the OPC 1 without rotating it, the occurrence of image flow can be prevented as in the first embodiment.
Further, the method of providing the OPC heater 7 inside the OPC raw tube as in the first embodiment has a problem that the configuration is complicated and the exchangeability of the OPC 1 is poor. However, in the case of heating with warm air as in the third embodiment, the configuration is easy, and a configuration with good exchangeability of the OPC 1 can be adopted.
In addition, since the temperature inside the machine rises during normal image formation, a fan is provided to cool the inside of the machine. In this configuration, when power is not supplied to the heating element, cooling is performed during normal image formation. It can function as a device, which simplifies the device and reduces costs.

FIG. 7 is a graph showing image flow at 20 ° C. and 10%. FIG. 8 is a graph showing the image flow at 32 ° C. and 80%. When OPC with improved wear resistance is used, image flow may occur in a high humidity environment other than directly under CH in addition to image flow directly under the charging device (CH).
Referring to FIGS. 7 and 8, there is no image flow at rank 3. At rank 2.5, the characters are legible, but image flow is seen in the halftone image. At rank 2, character interpretation is impossible.
FIG. 9 is a schematic perspective view showing a configuration with a diversion with respect to a circled portion of the schematic perspective view of FIG. FIG. 10 is a schematic perspective view showing a configuration without diversion with respect to a circled portion of the schematic perspective view of FIG.
In the fourth embodiment, the OPC 1 is stopped when the humidity is low, and the OPC 1 is driven when the humidity is high, thereby heating the portions other than the portion facing the charging device (CH) 2.
In the third embodiment described above, the warm air is divided into the charging device CH2 and the OPC 1, but in the present embodiment, it is configured so that whether or not to split the flow can be selected. In a state other than a high humidity environment, the OPC 1 is not driven and stopped, and since the flow is not divided so as to heat only the portion directly under CH2, the temperature is increased more efficiently than when the flow is divided.
When the humidity is high, the entire OPC 1 is heated by rotating the OPC 1. At this time, it was possible to heat uniformly from the inside and the surface of the OPC 1 by dividing the flow.

In the configuration of the present embodiment, when the OPC 1 is driven while the OPC 1 is heated, the OPC temperature reaches 40 ° C. in about 90 seconds at room temperature, and then the image flow can be substantially eliminated by rotating for about 150 seconds.
For this reason, in this embodiment, the OPC 1 is driven for a total of about 300 seconds. When the OPC 1 is driven, a development bias is applied at a normal charging potential to drive the development. By adopting a configuration in which the OPC photoconductor is heated, the configuration becomes simple, the exchangeability of the OPC photoconductor is improved, and the cost can be reduced, for example, by being combined with a cooling device.
As in the present embodiment, in a high humidity environment, the OPC 1 is rotated after heating the portion immediately below the CH2, and the OPC 1 is heated by a heater that heats the portion immediately below the CH2, thereby eliminating the high humidity image flow. As described above, the image flow under high humidity can be sufficiently eliminated by heating to about 40 to 45 ° C.
In this embodiment, heating means using warm air is used. However, as in the first embodiment, the OPC 1 is driven using the planar heater 7 or the like opposed to CH2, and the portions other than the CH2 opposed portion are heated. Similar effects can be obtained.
FIG. 11 is a schematic view showing the configuration of the fifth embodiment of the present invention. FIG. 12 is a flowchart for explaining the operation of the fifth embodiment of FIG. An IH heater 7 using an induction heating method as a first heating means is provided inside the OPC element tube facing the transfer separation device 4 on the upper side of the photosensitive member 1, and a nichrome wire is used as a second heating means in other portions. The planar heater 15 (in the figure: dotted line portion) is provided.
Although not shown, a temperature detection unit for detecting the OPC temperature heated by the first heating unit 7 and a temperature detection unit for detecting the OPC temperature heated by the second heating unit 15 are provided, each 55 ° C. for 180 seconds. The temperature is controlled to be kept at 40 ° C. or higher. In addition, an environmental sensor (not shown) is provided at an appropriate position on the main body that is not easily affected by the OPC temperature.

This will be described based on the flowchart of FIG. The power is turned on (S21), and it is determined whether or not 3 hours or more have passed after the exhaust fan (not shown) is stopped (S22). If 3 hours or more have passed, control of the first heating means is started (S23). . It is determined whether 180 seconds have elapsed when the temperature of the OPC photoreceptor 1 is 55 ° C. or higher (S24). If 100 seconds have elapsed, the first heating means is turned off (S25).
Further, it is determined whether or not the absolute temperature is 0.013 or higher (S26). If the absolute temperature is 0.013 or higher, the control of the second heating means is started (S27). Next, it is determined whether 180 seconds have passed when the temperature of the OPC photoreceptor 1 is 40 ° C. or higher (S28). If 180 seconds have passed, the second heating means is turned off (S29).
In the fourth embodiment, since heating is performed by one heating means, the cost is reduced, but heating takes time. In the fifth embodiment, it is possible to start up in a shorter period of time than in the fourth embodiment by appropriately applying heat to a place where a necessary amount of heat is required.
In addition, even if the above heating means is not supplied with electric power from a commercial power supply, there is no problem even if electric power is supplied from an auxiliary power supply of the power storage device.
In this image forming apparatus, there is a means for heating the part other than the part facing the charging device / transfer apparatus, and by determining whether or not to warm according to the detection value of the environmental sensor, the image flow of the facing part is of course determined. It is possible to eliminate the occurrence of image flow at portions other than the portion facing the charging device / transfer device such as in high humidity.

1 is a schematic diagram showing a first embodiment of an image forming apparatus according to the present invention. 2 is a flowchart for explaining the operation of the image forming apparatus according to the first embodiment shown in FIG. FIG. 5 is a schematic diagram showing a configuration of a second embodiment of the present invention in which a transfer separation device is on the upper side of the OPC and a charging device is on the lower side. Schematic explaining the structure of the 3rd Embodiment of this invention. The schematic perspective view explaining 3rd Embodiment of FIG. The flowchart explaining operation | movement of 3rd Embodiment. The figure which shows the image flow in 20 degreeC10% by a graph. The figure which shows the image flow in 32 degreeC80% with a graph. FIG. 6 is a schematic perspective view showing a configuration with a diversion with respect to a circled portion of the schematic perspective view of FIG. 5. FIG. 6 is a schematic perspective view showing a configuration without a diversion with respect to a circled portion of the schematic perspective view of FIG. 5. Schematic which shows the structure of the 5th Embodiment of this invention. 12 is a flowchart for explaining the operation of the fifth embodiment of FIG.

Explanation of symbols

1 OPC (photoconductor)
2 Charging device (CH)
4 Transfer device (Transfer separation device)
7 First heating means (planar heater, IH heater)
11 PTC heater (heating element)
15 Second heating means (planar heater)

Claims (4)

In an electrophotographic image forming apparatus including an organic photoreceptor, a charging device, and a transfer device,
A heating means for heating at least a portion of the organic photoreceptor facing the charging device or the transfer device;
Control means for controlling the heating means,
The control means causes the heating means to generate heat when the organophotoreceptor is stopped for 3 hours or longer, so that at least a portion of the organophotoreceptor facing the charging device or the transfer device is set to 50 ° C. or more. An image forming apparatus that is heated .   The image forming apparatus according to claim 1, wherein the heating unit heats the charging device on the upper side of the organic photoconductor or an upper portion of the organic photoconductor facing the transfer device.   The image forming apparatus according to claim 1, wherein the heating unit blows warm air to the organic photoreceptor. In addition to the heating means, another heating means for heating the portion other than the organic photoconductor portion heated by the heating means is provided, and the control means heats by the other heating means according to the detection result of the environmental sensor. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus determines whether or not.

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