JP2003263073A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent not only a cleaning failure that is caused by an agglomeration which is very likely affected by a low humidity environment but also a cleaning failure that is caused by slip due to μ-up of a photoreceptor drum and a cleaning blade which very likely affects a durable drum in a low humidity environment. <P>SOLUTION: According to durable time of the photoreceptor drum, drum heater control is switched. In the beginning of the durable time, the drum heater is kept turned off in a low humidity environment. When the durable time exceeds a predetermined time, the control is switched so that the drum heater is turned on only in the process of copying on one side of a sheet. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer or a facsimile which forms an image by using, for example, an electrophotographic system or an electrostatic recording system. The present invention relates to an image forming apparatus having the same.

[0002]

2. Description of the Related Art For example, in an image forming apparatus to which an electrophotographic technique is applied, an electrophotographic photosensitive member, which is an image bearing member, is repeatedly used after undergoing steps such as charging, development, transfer and cleaning.

That is, referring to FIG. 5, the operation of the conventional electrophotographic image forming apparatus will be described. In the image forming apparatus, for example, a drum type electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") is used as an image carrier. The surface of the photosensitive drum 1 is charged by the charger 6 during image formation, and then the surface is exposed by the exposure device 7 to form an electrostatic latent image. The developing device 8 develops the electrostatic latent image with a developer (toner) as a developer image (toner image). The toner image formed on the photosensitive drum 1 is transferred to the recording material P fed from the recording material cassette 10 by the action of the transfer device 9, and then, via the conveying device 11, the fixing roller 12 of the fixing device 12.
It is nipped and conveyed between a and the pressure roller 12b. The toner image is thermally fixed on the recording material P between the fixing roller 12a and the pressure roller 12b, and then discharged to the outside of the apparatus.

After the transfer, the transfer residual toner adhered on the photosensitive drum 1 is removed by a cleaning blade 13 as a cleaning means. The photosensitive drum 1 whose surface has been cleaned repeatedly enters the next image forming operation. Therefore, the surface of the photosensitive drum 1 must always be clean in each image forming process.

Therefore, when the cleaning operation is incomplete or the cleaning performance deteriorates with use, the cleaning state becomes incomplete, so-called poor cleaning occurs, and the quality of the formed image may be significantly deteriorated. There is.

As the cleaning means for removing the residual toner from the electrophotographic photosensitive member, various means have been proposed and implemented in the past. Among them, the one that presses the edge of a plate-shaped cleaning blade made of an elastic material such as urethane rubber against the electrophotographic photosensitive member to scrape off the residual toner has a simple structure, is small and compact, and has an excellent toner removing function. Therefore, it is widely used.

However, even with such a cleaning means, the toner accumulated at the edge portion may be solidified and lifted by the cleaning blade without dropping due to long-term use. As a result, the cleaning function is deteriorated, and the toner adheres to and fuses with the electrophotographic photosensitive member, causing deterioration in image quality, which may cause various inconveniences.

Further, the surface of the electrophotographic photosensitive member is finely scratched by repeated image formation, and further ozone products and filming substances are fixed, the surface condition is gradually deteriorated, and the friction coefficient is also increased. It is in. In addition, the frictional force between the electrophotographic photosensitive member and the cleaning blade contacting the photosensitive member acts more than necessary, and the cleaning blade tends to curl up, resulting in defective cleaning.

On the other hand, conventionally, the electrophotographic photosensitive member is controlled so as to be maintained at a constant temperature. For example, as shown in FIG. 5, an exothermic heater 2 for heating the photosensitive drum 1 is embedded inside the photosensitive drum 1, and generally, heating control is performed to a temperature near 40 to 50 ° C. higher than room temperature. To be done.

The heating of the heating heater 2 is controlled by controlling the temperature of the photosensitive drum 1 heated by the heating heater 2 by the thermistor 3.
Is detected by the control unit (CPU) 5 and the power supply from the power source 4 to the heating heater 2 is controlled based on the temperature information.

By the way, the purpose of heating the photosensitive drum 1 by the heating heater 2 is as follows.

(1) Flow image prevention: Under high temperature and high humidity conditions, water molecules are adsorbed on the surface of the photosensitive drum 1 and the surface resistance of the photosensitive drum 1 is lowered, so that an electrostatic latent image is dripping. A so-called flow image is generated. This phenomenon can be prevented by heating and evaporating water molecules appropriately.

(2) Stabilization of cleaning characteristics: The cleaning blade 13 is generally made of urethane rubber or the like, and its viscoelastic characteristics depend on temperature. Therefore, it is desirable to keep the temperature constant.

The items (1) and (2) above largely depend on environmental conditions. In particular, the flow image phenomenon of (1) above is generally more likely to occur in a high temperature and high humidity environment.

In addition, the cleaning property of the above item (2) is often apt to deteriorate in a low humidity environment. This is because the electrostatic cohesion tendency of the transfer residual toner is severe in a low humidity environment,
This is because the transfer residual toner exerts a strong load on the cleaning blade 13. From the viewpoint of the temperature, the higher the temperature, the more the transfer residual toner becomes caking at the edge of the cleaning blade 13, which further deteriorates the cleaning property.

Further, the frictional force between the photosensitive drum 1 and the cleaning blade 13 gradually changes according to the durability time from the initial stage of the photosensitive drum 1, and the frictional force is small at the initial stage of the durability, but as the durability progresses. growing. This occurs because the surface of the photosensitive drum 1 is polished by the cleaning blade 13, and the surface of the photosensitive drum 1 is rough in the initial stage.
3 has a small contact area with the photosensitive drum 1 and is slippery,
When the durability is improved and the surface of the photosensitive drum 1 is mirror-finished, the contact area between the cleaning blade 13 and the photosensitive drum 1 is increased and the frictional force is increased. The change of the surface property (surface roughness Ra) of the photosensitive drum 1 is as shown in FIG. 7 when the durable number of the photosensitive drum 1 is shown, and the change is sharp from the initial stage to about 300K.

Further, the contact pressure between the cleaning blade 13 and the photosensitive drum 1 is not constant in the longitudinal direction,
Since there is a certain distribution, when such a surface roughness Ra changes abruptly, uneven polishing is likely to occur in the longitudinal direction, and unevenness of the surface roughness Ra occurs in the longitudinal direction of the photosensitive drum 1. That is, in the longitudinal direction of the photosensitive drum 1, there are a slippery place and a slippery place. This promotes the deterioration of the cleaning property due to the caking of the transfer residual toner, and the durable number of the photosensitive drums 1 is about 30 from the initial stage.
During 0K sheets, defective cleaning easily occurs.

In view of these points, conventionally, a method of lowering the temperature of the photosensitive drum 1 can be considered in a low humidity environment in which the transfer residual toner has a high tendency to electrostatically aggregate.

Specifically, conventionally, the heating control of the photosensitive drum 1 by the heating heater 2 is always completely turned off in a low humidity environment.
The method was taken.

[0020]

However, in the method of constantly turning off the heat generating heater 2 in the low humidity environment as described above, in order to stabilize the characteristics of the cleaning blade 13, the temperature of the cleaning blade 13 is kept above a certain temperature. It became difficult to keep the above, and the following problems sometimes occurred.

The cleaning blade 13 is used so that the value of the viscoelastic modulus tan δ of its viscoelastic property is in the range of 0.18 to 0.40 as a result of the earnest studies made by the present inventors. However, it is suitable in terms of stability of cleaning property and prevention of toner adhesion to the electrophotographic photosensitive member.

FIG. 6 shows a typical cleaning blade 1
The characteristic of the viscoelastic modulus tan δ of 3 with respect to temperature is shown. Figure 6
As can be seen from the above, until the temperature decreases and reaches the peak temperature of the viscoelastic modulus tan δ of about 20 ° C., the value of tan δ increases as the temperature decreases. tan δ means the ratio of viscosity / elasticity in the viscoelastic property, and a higher value of tan δ indicates higher viscosity.

In the method in which the heating heater 2 is always turned off in the low humidity environment as in the above-mentioned conventional example, the temperature of the cleaning blade 13, that is, the temperature of the photosensitive drum 1 is 30.
It may be below ℃. In particular, immediately after the main body of the apparatus is turned on in a low temperature environment, or when the recording material P draws heat from the photosensitive drum 1 due to contact between the recording material P and the photosensitive drum 1 at the transfer portion during single-sided image formation. is there. In this case, as can be seen from FIG. 6, the viscoelastic modulus tan δ has a value higher than 0.4, and the cleaning blade 13 is used in a high viscosity state.

As described above, when the cleaning blade 13 is used in a high viscosity state, the cleaning blade 1
There is a high possibility that cleaning failure will occur due to curling. Also, a low elastic term means that, if stick-slip occurs as a result, its frequency is low, which means that a cleaning failure may occur.

This stick-slip phenomenon easily occurs when the durability of the photosensitive drum 1 is advanced and the friction coefficient between the surface of the photosensitive drum 1 and the cleaning blade 13 is increased.

In the figure, the surface roughness Ra of the photosensitive drum 1 is
This phenomenon becomes remarkable from about 1000K sheets where the image becomes smaller and becomes a mirror surface.

When the ratio of the elastic term of the cleaning blade 13 is high, the frequency of vibration generated in the cleaning blade 13 is high. Therefore, even if stick-slip occurs, its effect does not reach cleaning failure.

On the other hand, if the cleaning blade 13 is used in a state where the viscosity is higher, sticking slips will eventually cause the cleaning blade to curl up, resulting in slipping through and possibly poor cleaning.

Therefore, an object of the present invention is to provide an image forming apparatus which can always maintain good cleaning performance of the image carrier by the cleaning means.

Another object of the present invention is not only to eliminate defective cleaning due to electrostatic agglomeration of transfer residual toner to the cleaning means, which is likely to occur in a low humidity environment, but also to increase the friction coefficient of the surface of the image carrier due to durability. It is an object of the present invention to provide an image forming apparatus capable of preventing a cleaning failure in which residual developer slips through a cleaning unit due to stick-slip that tends to occur in some cases.

[0031]

To achieve the above object, the present invention provides an image carrier, heating means for heating the surface of the image carrier, and a latent image formed on the image carrier. A developing means for visualizing the developer image as a developer image, a transferring means for transferring the developer image onto a recording material, and a cleaning means for removing the developer remaining on the surface of the image bearing member. In an image forming apparatus for forming an image, the cumulative rotation time of the image carrier is measured from the initial stage, and the cumulative rotation time is in a low humidity environment from the initial stage of the image carrier to a predetermined cumulative time. The heating temperature control of the image carrier by the heating unit is always turned off, and after the accumulated rotation time is a predetermined cumulative time, the heating temperature control of the image carrier by the heating unit in a low humidity environment is performed as described above. Single-sided image form on recording material It is characterized in that the ON only during.

In the above-described structure of the present invention, in the initial stage of the durability of the image bearing member, the heating temperature control of the image bearing member by the heating means in the low humidity environment is always turned off to lower the surface temperature of the image bearing member. Therefore, electrostatic aggregation of the transfer residual toner is less likely to occur. Further, when the durability of the image bearing member progresses and the surface becomes a mirror surface, the surface temperature of the image bearing member is raised to raise the temperature of the cleaning blade, and particularly, at the time of single-sided image formation, the recording material and the image bearing member in the transfer section. Since the contact between the recording material and the recording material keeps the heat of the image carrier from being taken away, it is possible to prevent cleaning failure due to stick slip.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

(Embodiment 1) FIG. 1 shows a schematic configuration of an embodiment of an image forming apparatus according to the present invention. The image forming apparatus according to the present exemplary embodiment is configured to be able to form an image on both sides of a recording material by a through-pass double-sided method.

The image forming apparatus of this embodiment is provided with a drum type electrophotographic photosensitive member (photosensitive drum) 1 as an image bearing member. A charger (charging means) is provided around the photosensitive drum 1.
6, exposure device (exposure means) 7, developing device (developing means)
8, a transfer device (transfer means) 9, a cleaning blade (cleaning means) 13, and the like are provided.

Further, the recording material P such as recording paper or OHP sheet is sandwiched with the transfer portion between the transfer device 9 and the photosensitive drum 1 interposed therebetween.
The recording material cassette 10, which stores the recording material P, the conveying device 11, the fixing device 12, the reversing roller 14, the re-feeding belt 20, and the like are arranged in this order from the upstream side in the conveying direction.

The photosensitive drum 1 has a photosensitive layer on a cylindrical base body made of metal (aluminum, for example), and is driven at a predetermined speed in the arrow direction (clockwise direction) by a driving means (not shown). It is driven to rotate.

Inside the photosensitive drum 1, a planar heater 2 is arranged along the inner circumference of the photosensitive drum 1 for about one round. Then, the temperature adjustment control (heating temperature control) of the photosensitive drum 1 by the heating heater 2 detects the temperature of the photosensitive drum 1 heated by the heating heater 2 with the thermistor 3, and the power source 4 generates heat based on the temperature information. Heater 2
It is performed by controlling the power supply to the controller 5.

As will be described later in detail, the control device (control means) 5 is based on environmental temperature / humidity information around the image forming apparatus detected by the temperature / humidity detection detection means (temperature / humidity sensor) 21. The power supply from the power source 4 to the heater 2 is controlled to set the photosensitive drum 1 at a predetermined temperature.

In this embodiment, the charger 6 is a corona charger, and uniformly charges the peripheral surface of the photosensitive drum 1 by corona discharge. The exposure device 7 performs image exposure according to the input image information on the photosensitive drum 1 charged by the charger 6 to form an electrostatic latent image.

The developing device 8 attaches toner to the electrostatic latent image formed on the photosensitive drum 1 to visualize it as a toner image. Further, in the present embodiment, the transfer device 9 is a corona charger, and transfers the toner image formed on the photosensitive drum 1 between the transfer device 9 and the photosensitive drum 1 onto the recording material P.

The fixing device 12 of this embodiment has a fixing roller 12a having a built-in heater, and a pressure roller 12b pressed against the fixing roller 12a. Further, the fixing device 12
Has a thermistor 22 for detecting the surface temperature of the fixing roller 12a, and the control device (CPU) 5 controls power supply to a heater (not shown) in the fixing roller 12a based on the detected information. The temperature is controlled.

The cleaning blade 13, which is a cleaning means, contacts the photosensitive drum 1 and removes the transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer.

Next, the image forming operation will be described. The image forming apparatus of this embodiment can perform single-sided image formation in which an image is formed on only one side of the recording material P and double-sided image formation in which images are formed on both sides of the recording material P.

The photosensitive drum 1 is rotationally driven at a predetermined speed in the direction of the arrow (clockwise) in the drawing by a driving means (not shown),
The surface of the charger 6 is uniformly charged by the charger 6. Then, image exposure is performed on the surface of the photosensitive drum 1 from the exposure device 7 in accordance with the input image information, and the charge of the exposed portion is removed to form an electrostatic latent image. This electrostatic latent image is visualized as a toner image by the developing device 8 with toner attached thereto.

When the toner image on the photosensitive drum 1 reaches the transfer portion between the photosensitive drum 1 and the transfer unit 9, the recording material P fed from the recording material cassette 10 is registered at the timing. It is fed by rollers 15. Then, the toner image on the photosensitive drum 1 is transferred onto the surface (one surface) of the recording material P by the transfer device 9.

The recording material P having the toner image transferred on one side is
The fixing roller 12a of the fixing device 12 by the conveying device 11
And the pressure roller 12b. Then, the recording material P is heated and pressed between the fixing roller 12a and the pressure roller 12b to fix the toner image.

After that, at the time of single-sided image formation, the fixing device 1
The recording material P having the toner image fixed on one side by 2 is discharged to the outside of the apparatus without being conveyed to the re-feeding belt 20 by the reversing roller 14 as described later.

On the other hand, at the time of double-sided image formation, the fixing device 12
The recording material P having the toner image fixed on one side thereof is then conveyed onto the re-feed belt 20 by the reversing roller 14. The recording material P conveyed onto the re-feed belt 20 is
It is again conveyed to the transfer portion between the photosensitive drum 1 and the transfer device 9. Then, image formation is performed on the other surface on which the toner image is not transferred in the same manner as described above, and then the image is discharged to the outside of the apparatus.

As can be seen from FIG. 2 as well, at the time of double-sided image formation, the recording material P1 having the image A formed on one surface is conveyed by the reversing roller 14 onto the re-feeding belt 20 and re-feeding. It is conveyed again from the belt 20 to the transfer portion between the photosensitive drum 1 and the transfer device 9. Then, the double-sided image recording material P2 having the image B formed on the other surface as described above is carried out of the apparatus. In this way, the recording material P during double-sided image formation is re-conveyed on the re-feeding belt 20 without being temporarily stopped, so that the image forming speed per hour is dramatically improved.

In each image forming step, the transfer residual toner remaining on the photosensitive drum 1 after the toner image is transferred is removed by the cleaning blade 13.

In this embodiment, the photosensitive drum 1 has a diameter Φ.
A 108 mm a-Si drum was used.

As the cleaning blade 13, urethane rubber having a rubber hardness of 81 °, a peak temperature of the viscoelastic coefficient tan δ of the viscoelastic property of 25.5 ° C., and a thickness of 3 mm was used. Cleaning blade 13 of this embodiment
The viscoelastic properties of are as shown in FIG. The cleaning blade 13 is not limited to this, and normally, a blade made of an elastic material having a peak temperature of the viscoelastic modulus δ of 25 ± 5 ° C. can be preferably used.

In this embodiment, the heating heater 2 used is 80W.

By the way, at room temperature and low humidity (for example, 23 ° C. /
Under the environment of 5% RH), the heater 2
The temperature transition of the photosensitive drum 1 when the heating control of the photosensitive drum 1 is always completely turned off is shown by the curves X and Y in FIG.
become that way.

That is, the power switch of the main body is turned on when the image forming apparatus is not used at all, and the fixing device 12
Immediately after the "waiting state" in which the main body is in the standby state for heating temperature control of the printer, and the "standby state" in which the apparatus main body is ready for image formation, "single-sided image formation on the recording material P is performed. , The surface temperature of the photosensitive drum 1 changes as shown by the curve X in FIG. Similarly, when the "double-sided image formation" is continuously performed on the recording material P, the temperature transition of the photosensitive drum 1 is as shown by a curve Y in FIG.

As shown in FIG. 3, during double-sided image formation,
After the recording material P passes through the fixing device 12, the image forming process for the second surface is continuously performed again. Therefore, the heat applied to the recording material P from the fixing device 12 is applied to the photosensitive drum 1 during the transfer process by the transfer device 9. Granted. As a result, the photosensitive drum 1
Surface temperature increases with the number of durable sheets.

On the other hand, at the time of single-sided image formation, the recording material P, which has substantially the same temperature as the environment (external) environment around the image forming apparatus in the recording material cassette 10, absorbs heat from the photosensitive drum 1 during the transfer process. Therefore, the temperature rise is slow,
The surface temperature of the photosensitive drum 1, that is, the temperature at the edge of the cleaning blade 13 remains below 30 ° C. for a while. In this state, as shown in FIG. 6, in the cleaning blade 13 of this embodiment, the viscoelastic modulus tan δ.
Is higher than 0.4.

As described above, in the conventional method, image formation is performed for a while while the temperature of the cleaning blade 13 is 30 ° C. or lower, that is, the value of tan δ of the cleaning blade 13 is higher than 0.4. As a result, conventionally, when the durability of the photosensitive drum 1 is increased and, for example, when the total number of image formations reaches about 1000K, one-sided image formation is continuously performed immediately after the standby state, several hundreds to several thousands of sheets are formed. Occasionally, defective cleaning occurs due to the slip-through state caused by stick-slip.

On the other hand, in the image forming apparatus of this embodiment, when the cumulative number of image formations on the photosensitive drum 1 is 500K or more under a low humidity environment, the photosensitive drum 1 is heated by the heating heater 2 during single-sided image formation. Turn on heating control.

On the other hand, in the present embodiment, while the image forming apparatus is in the "wait state" in which the image forming apparatus is in a standby state for preparation for image formation, the apparatus main body can form an image, and the image forming apparatus does not perform "standby". During the “state” and during double-sided image formation on the recording material P, the heating control of the photosensitive drum 1 by the heating heater 2 is turned off.

That is, in this embodiment, when the cumulative number of image formations on the photosensitive drum 1 is 500K or more, the humidity is set to the predetermined value A based on the detection result of the temperature / humidity sensor 21.
If it exceeds the limit, the photosensitive drum 1 by the heating heater 2
When the heating temperature control is constantly ON and the humidity is equal to or lower than the predetermined value A, the heating temperature control of the photosensitive drum 1 by the heating heater 2 is turned ON only during the single-sided image formation on the recording material P. Table 1 shows the control mode of this embodiment.

[0063]

[Table 1]

In the present embodiment, the environment in which the heating control by the heating heater 2 is always turned on is that the absolute humidity (water content) obtained based on the environmental temperature / humidity data detected by the temperature / humidity detection sensor 21 is 9 g / kg DryAi
It was assumed that r (predetermined value A) was exceeded.

Further, the environment in which the heating control of the photosensitive drum 1 by the heat generating heater 2 is turned on only when the one-sided image is formed is an absolute humidity (based on the environmental temperature / humidity data detected by the temperature / humidity detection sensor 21). Water content) 9g
/ Kg DryAir (predetermined value A) or less.

In the present embodiment, the set temperature (target temperature) for heating control of the photosensitive drum 1 by the heater 2 is 42 ° C.
When the heating control by the heating heater 2 is ON, the controller 5 controls the power supply to the heating heater 2 so that the temperature of the surface of the photosensitive drum 1 becomes the target temperature.

For example, room temperature and low humidity (for example, 23 ° C./5
% RH), according to the control according to the present embodiment, the transition of the surface temperature of the photosensitive drum 1 becomes as shown by the curve Z in FIG. As can be seen from FIG. 3, according to this embodiment,
When one-sided image formation is continuously performed, particularly even immediately after the image forming apparatus enters the “standby state”, the surface temperature of the photosensitive drum 1 immediately rises. As a result, the cleaning blade 13 is moved to the viscoelastic modulus tan
There was almost no time during use when δ was higher than 0.4, and cleaning failure in a slip-through state due to stick slip did not occur.

Further, in this embodiment, in a low humidity environment (9 g / kg DryAir in this embodiment), when the cumulative number of image formations on the photosensitive drum 1 is less than 500 K, the photosensitive drum 2 is heated by the heating heater 2 as in the prior art. The heating control of No. 1 is turned off even during single-sided image formation to suppress electrostatic aggregation of transfer residual toner. Actually, in a low humidity environment, when the height of the agglomerate of the transfer residual toner at the edge portion of the cleaning blade 13 is measured at a predetermined number of sheets, when the heating control of the photosensitive drum 1 by the heating heater 2 is turned on. It was about 2 to 1.3 cm, but the heating control of the photosensitive drum 1 by the heating heater 2 was turned off under the same conditions.
Then, it becomes about 0.3 to 0.5 cm, which does not affect the cleaning property.

As described above, in the initial stage of the photosensitive drum 1, cleaning failure due to electrostatic agglomeration of the transfer residual toner, which is likely to occur due to the surface roughness of the photosensitive drum 1 in the longitudinal direction, is controlled by the heating heater 2 for heating the photosensitive drum 1. Since it is turned off and the surface temperature of the photosensitive drum 1 is lowered to suppress the generation of agglomerates, defective cleaning can be eliminated.

As described above, in the present embodiment, the recording material P absorbs heat from the photosensitive drum 1 in the transfer step during the single-sided image formation, and the surface temperature of the photosensitive drum 1 is lowered, whereby the temperature of the cleaning blade 13 is lowered. And viscoelastic modulus ta
Focusing on the phenomenon that cleaning failure occurs due to a high slippage value due to stick slip, and this phenomenon occurs when the surface of the photosensitive drum 1 becomes a mirror surface due to the progress of durability of the photosensitive drum 1. I also focused on that. Then, in a low humidity environment, the heating control of the photosensitive drum 1 by the heating heater 2 is turned on during single-sided image formation. This can prevent the temperature of the cleaning blade 13 from decreasing during single-sided image formation, particularly during single-sided continuous image formation immediately after the main body is powered on. Therefore, it is possible to prevent cleaning failure due to stick slip without using the cleaning blade 13 in a state where the viscoelasticity coefficient δ is high.

Also, paying attention to the fact that cleaning failure due to electrostatic agglomeration of transfer residual toner easily occurs in the initial stage of the photosensitive drum 1, and in the initial stage of the photosensitive drum 1, the heating control of the photosensitive drum 1 by the heating heater 2 is performed. By switching to OFF even during single-sided image formation, it is possible to eliminate cleaning failure due to electrostatic aggregation of transfer residual toner.

(Embodiment 2) In Embodiment 1, the heating control of the photosensitive drum 1 by the heating heater 2 is switched depending on the cumulative number of image formations of the photosensitive drum 1, but the cumulative rotation time of the photosensitive drum 1 is measured, The heating control of the photosensitive drum 1 by the heating heater 2 may be switched at a predetermined cumulative rotation time.

In this embodiment, means for counting the cumulative number of rotations of the photosensitive drum 1 is provided, and the cumulative rotation time is converted from the cumulative number of rotations. In the present embodiment, the cumulative rotation time is 100 hours, and the photosensitive drum 1 by the heating heater 2 is used.
The heating control of is switched.

To be precise, the change in the surface roughness of the photosensitive drum 1 depends more on the cumulative rotation time of the photosensitive drum 1 than on the cumulative number of image formations on the photosensitive drum 1. Therefore, in this embodiment,
The heating control of the photosensitive drum 1 by the more accurate heating heater 2 can be switched.

(Third Embodiment) Next, another embodiment of the image forming apparatus according to the present invention will be described. The image forming apparatus of this embodiment has basically the same configuration as the image forming apparatus of the first embodiment. Therefore, elements having the same function and configuration are designated by the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment, the temperature / humidity detection sensor 2
Based on the environmental temperature / humidity data according to No. 1, when the humidity is less than or equal to the predetermined value B, the heating control of the photosensitive drum 1 by the heating heater 2 is turned ON only at the time of single-sided image formation.

On the other hand, in the present embodiment, based on the environmental temperature / humidity data from the temperature / humidity detection sensor 21, when the humidity is below the predetermined value B and the temperature exceeds the predetermined value C, the recording is performed. The heating control of the photosensitive drum 1 by the heating heater 2 is turned on only when the one-sided image is formed on the material P, and is turned off during other times.

On the other hand, when the humidity is less than the predetermined value B and the temperature is less than the predetermined value C, the preparation for the image forming apparatus to be able to form an image in addition to the one-sided image formation on the recording material P is performed. During the "wait state" during standby, and during the "standby state" in which the apparatus main body is capable of image formation and image formation is not being performed, the heating control of the photosensitive drum 2 by the heating heater 2 is turned on, and both sides are turned on. The heating control is turned off only during image formation.

Also in this embodiment, when the humidity exceeds the predetermined value A based on the environmental temperature / humidity data from the temperature / humidity detection sensor 21, the heating temperature control of the photosensitive drum 1 by the heating heater 2 is always performed. Turn on. Table 2 shows the control mode of this embodiment.

[0080]

[Table 2]

According to this embodiment, the stability of the cleaning property under a low temperature and low humidity environment is further increased.

To further explain, in a low temperature and low humidity environment (for example, 15 ° C./10% RH), the power switch of the main body is turned on after the image forming apparatus is not used at all, and the “wait state” is set. Immediately after the main body of the apparatus enters the "standby state" in which the image can be formed, the recording material P
The temperature transitions of the photosensitive drum 1 when continuous single-sided image formation is performed are as shown by curves α and β in FIG. 4 in Example 1 and this example, respectively.

That is, in the case of the control of the first embodiment, the surface temperature of the photosensitive drum 1 at the start of single-sided image formation is low in a low temperature environment. As a result, the temperature rise is slow even though the heating control of the photosensitive drum 1 is turned on at the time of single-sided image formation, and several hundreds of sheets continue for 30 ° C. or less. As a result, there is a possibility that cleaning failure in a slip-through state due to stick-slip may occasionally occur.

On the other hand, in this embodiment, in a low humidity environment,
Moreover, when the temperature is low, the heating control of the photosensitive drum 1 by the heat-generating heater 2 is turned on while the image forming apparatus is in the "wait state" and the "standby state" in addition to the one-sided image formation. As a result, when the one-sided image formation is started, the surface temperature of the photosensitive drum 1 is already 30%.
It has risen to near ℃. As a result, it is possible to completely eliminate defective cleaning in a slip-through state due to stick slip.

In this embodiment, the environment in which the heating control of the photosensitive drum 1 by the heating heater 2 is always ON is the absolute humidity (moisture content) obtained based on the environmental temperature / humidity data detected by the temperature / humidity detection sensor 21. Amount) is 9g / k
The case where gDryAir (predetermined value A) was exceeded was determined.

Further, the environment in which the heating control of the photosensitive drum 1 by the heat generating heater 2 is turned on at the time of single-sided image formation is
The absolute humidity (water content) calculated based on the environmental temperature / humidity data detected by the humidity sensor 21 is 9 g /
The case was less than or equal to kg DryAir (predetermined value A). Then, when the temperature is 9 g / kg DryAir (predetermined value A) or less and the temperature exceeds 22 ° C. (predetermined value C), the heating control is turned ON only during single-sided image formation, and the humidity is 9 g / kgDr.
It is below yAir and the temperature is 22 ° C (predetermined value C)
In the following cases, the heating control was turned on during the "wait state" and during the "standby state" in addition to the one-sided image formation.

As described above, according to the present embodiment, it is possible to suppress the temperature of the cleaning blade 13 from being lowered, especially when a single-sided image is formed immediately after the main body is powered on in a low temperature environment. This makes it possible to prevent cleaning failure due to stick-slip without using the cleaning blade 13 in a state where the viscoelastic coefficient δ is high.

In each of the above embodiments, the image bearing member is described as a drum type electrophotographic photosensitive member (photosensitive drum), but the present invention is not limited to this.
Usually, as in each of the above-described embodiments, the image carrier is preferably a rotating body, and may be a belt, a film stretched around a frame, or the like.

Further, the heating means for heating the image bearing member is not limited to the heating heater provided in the drum type image bearing member in each of the above-mentioned embodiments. In some cases, the surface of the image carrier may be heated from the outside.

[0090]

As described above, according to the present invention, in the initial stage of durability of the image bearing member (from the initial stage to 300K sheets),
Due to the unevenness of the surface roughness Ra of the image carrier in the longitudinal direction, cleaning failure easily occurs due to electrostatic aggregation of transfer residual toner, and the durability of the image carrier is promoted (about 1000 K).
When the surface of the image bearing member is mirror-finished and the friction with the cleaning blade increases, attention is paid to the fact that cleaning failure due to stick slip easily occurs, and the heating temperature control of the image bearing member by the heating means in a low humidity environment is performed. Switching according to the durability time of the image carrier, in the initial stage of durability of the image carrier, the heating temperature control of the image carrier by the heating means in a low humidity environment is always turned off to lower the surface temperature of the image carrier, and When the durability of the image bearing member is advanced, the surface temperature of the image bearing member is raised to raise the temperature of the cleaning blade. Since the material is kept so that the heat of the image carrier is not taken away, cleaning failure and stick-slip due to electrostatic aggregation of transfer residual toner It was possible to prevent the cleaning failure due.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a schematic diagram for explaining a flow of a recording material when forming a double-sided image in an embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a graph showing a transition of the surface temperature of the photosensitive drum when single-sided and double-sided image formation is continuously performed under a room temperature and low humidity environment.

FIG. 4 is a graph showing a transition of the surface temperature of the photosensitive drum when single-sided image formation is continuously performed in a low temperature and low humidity environment.

FIG. 5 is a schematic configuration diagram of an example of a conventional image forming apparatus.

FIG. 6 Viscoelastic property tan δ of cleaning blade
It is a graph which shows the temperature change of.

FIG. 7 is a diagram showing changes in Ra of a photosensitive drum due to durability.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum (image carrier) 2 Exothermic heater (heating means) 3 Thermistor 4 Power supply 5 Control device (control means) 6 Charger (charging means) 7 Exposure device (exposure means) 8 Developing device (developing means) 9 Transfer Device (transfer means) 10 Recording material cassette 11 Conveying device 12 Fixing device (fixing means) 13 Cleaning blade (cleaning means) 14 Reversing roller (refeeding means) 15 Registration roller 20 Refeeding belt (refeeding means) 21 Temperature / humidity detection sensor (temperature / humidity detection means) 22 Fixing roller thermistor

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H027 DA13 DA14 DA31 DA38 DA45                       DE07 EA09 EA13 EE08 EF04                       EF12 FA13 JA12 JB19 JC01                       JC07                 2H028 BB02 BB04                 2H035 AZ01 AZ05 AZ09 BA06 BA10                       CA07 CB03 CZ03                 2H134 GA01 GB02 HD05 HD17 HD18                       HD19 KA28 KA30 KA31 KA33                       KB14 KC01 KC03 KD08 KH01                       KH04 KJ03 QA03 QA04

Claims (7)

[Claims] 1. An image carrier, heating means for heating the surface of the image carrier, developing means for visualizing a latent image formed on the image carrier as a developer image, and the developer image. An image forming apparatus for forming an image on the recording material, comprising: a transfer means for transferring the recording material onto the recording material; and a cleaning means for removing the developer remaining on the surface of the image carrier. The cumulative rotation time is measured, and during this cumulative rotation time from the initial stage of the image carrier to a predetermined cumulative time, the heating temperature control of the image carrier by the heating means in a low humidity environment is always turned off. After the predetermined cumulative time, the heating temperature control of the image carrier by the heating means in a low humidity environment is turned ON only during single-sided image formation on the recording material. Image forming apparatus. 2. The image forming apparatus is capable of performing double-sided image formation on the recording material, and in a low humidity environment, the double-sided image formation on the recording material does not depend on an accumulated rotation time of the image carrier. The image forming apparatus according to claim 1, wherein heating temperature control of the image carrier by the heating unit is turned off during image formation. 3. The image forming apparatus, in an environment of low temperature and low humidity, controls the heating temperature of the image carrier after a predetermined cumulative time from the initial rotation of the image carrier. During single-sided image formation on a recording material, during a standby state in which the image forming apparatus is ready for image formation, and during a standby state in which the image forming apparatus is capable of image formation and is not performing image formation. The image forming apparatus according to claim 1, wherein the image forming apparatus is turned on. 4. The image forming apparatus according to claim 1, 2 or 3, wherein the cumulative rotation time of the image bearing member is obtained from the cumulative number of durable images from the initial period of the image bearing member. 5. The image forming apparatus according to claim 1, wherein the heating unit is a heater provided inside the image carrier. 6. The cleaning blade according to claim 1, wherein the cleaning means is a cleaning blade formed of an elastic member for contacting the image carrier and removing the developer remaining on the surface of the image carrier. The image forming apparatus according to any one of claims. 7. The viscoelastic modulus t of the cleaning blade
The image forming apparatus according to claim 6, wherein the peak temperature of an δ is 25 ± 5 ° C.