JPH07104612A - Method for setting temperature of photoreceptive film for image forming device - Google Patents

Abstract

PURPOSE:To provide a dark decay control method in an image forming device capable of forming an image with uniform density even when dark decay on a photoreceptive film is fluctuated for various causes regardless of the cause of the fluctuation. CONSTITUTION:In this method for setting the temperature of the photoreceptive film 12 of the image forming device 11; first, the degree of the dark decay on the film 12 is detected by a surface potential meter 26 when a photoreceptor 13 is mounted. Next, the temperature of the film 12 is adjusted by a heater 24 corresponding to the detected degree of the dark decay of the film 12. Since the temperature of the film 12 correlates with the degree of the dark decay, the dark decay amount is made constant regardless of the kind of the photoreceptor 13 by adjusting the temperature of the film 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting the temperature of a photoconductor film of an image forming apparatus using electrophotography.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic technique has been actively developed as an electrostatic copying apparatus or a printing apparatus.

FIG. 7 is a system diagram of an image forming apparatus 1 using a conventional electrophotographic technique. The image forming apparatus 1 includes a rotatable photosensitive drum 3 having a photosensitive film 2 formed on its surface, a main charger 4 for uniformly applying a predetermined amount of electric charge to the photosensitive film 2, and a photosensitive film 2. An optical device 5 for exposing and forming an electrostatic latent image on the photoconductor film 2, a developing device 6 for developing the electrostatic latent image on the photoconductor film 2, and a photoconductor film 2 are formed. A transfer device 8 for transferring the toner image onto the recording paper 7, a cleaning device 9 having a cleaning blade for removing the toner remaining on the photosensitive drum 3, and an electric charge remaining on the photosensitive drum 3 are removed, A discharge lamp 10 for setting the surface potential of the photosensitive drum 3 to a predetermined uniform potential.
And so on.

According to the image forming apparatus 1, the main charger 4 uniformly applies a predetermined amount of electric charge to the photoconductor film 2, and then the optical device 5 irradiates the photoconductor film 2 with light. An electrostatic latent image is formed on the film 2. Thereafter, the developing device 6 supplies the toner onto the photoconductor film 2 to visualize the electrostatic latent image. The toner image on the photoconductor drum 3 is transferred to the transfer device 8
Is transferred onto the recording paper 7. After the transfer, the toner remaining on the photosensitive drum 3 is removed by the cleaning device 9. Next, the static elimination lamp 10 irradiates the photoconductor film 2 with light, removes the electric charge remaining on the photoconductor film 2, and equalizes the surface potential of the photoconductor film 2 to a predetermined potential. After that, the main charger 4 charges the photosensitive drum 3 again. These series of processes are continuously and repeatedly performed according to the rotation of the photosensitive drum 3.

In the prior art, an inorganic material or an organic material is used as a photosensitive material forming the photosensitive film 2. Se-based materials, amorphous Si-based materials, etc. are used as the inorganic materials. In recent years, organic materials are often used in terms of safety and workability. Organic photoreceptors using organic materials are classified into laminated organic photoreceptors and single-layer organic photoreceptors.

[0006]

However, the above-mentioned conventional technique has the following problems. That is, after a predetermined amount of electric charge is applied to the unit area of the photoconductor film 2 by the main charger 4, dark decay occurs in which a part of the electric charge is lost with the passage of time. Therefore, as the photosensitive drum 3 rotates, an arbitrary region of interest on the photosensitive film 2 moves from the charging position (position close to the main charger 4) to the developing position (position close to the developing device 6). In the meantime, the amount of charge in that area will decrease.

It is generally called dark decay that the surface potential of the photoconductor film 2 decreases without exposure. Since the photoconductor film 2 has different charge holding ability depending on its type,
There is a problem that the degree of dark attenuation varies depending on the type of the photoconductor film 2. Furthermore, the degree of this dark decay varies depending on various factors such as the environment in which the image forming apparatus 1 is installed even if the photoconductor films 2 of the same type are used. Image forming apparatus 1 and equipment conditions such as charge holding ability of the photoconductor film 2 and drum heater temperature
Machine conditions such as the environment in which the image forming apparatus 1 is installed
When different for each image forming apparatus 1, the degree of dark attenuation also changes.

The present invention has been made in order to solve the above problems, and its object is to keep the surface potential constant at the developing position by keeping the surface potential constant even when a photoconductor film having a different dark decay is used. It is an object of the present invention to provide a method for setting the temperature of a photoconductor film in an image forming apparatus capable of forming a stable image.

[0009]

A method for setting a temperature of a photosensitive film in an image forming apparatus according to the present invention comprises a photosensitive member having a photosensitive film, a charging unit for charging the photosensitive film, and the charged photosensitive member. A method for setting a temperature of a photoconductor film in an image forming apparatus, comprising: an exposing unit that irradiates a body film with light; and a developing unit that develops the exposed photoconductor film. A detection step of detecting the degree of dark decay in the photoconductor film, and adjusting the temperature of the photoconductor film based on the detected degree of dark decay, thereby changing the type of the photosensitive member. Without making the dark attenuation constant, thereby achieving the above object.

[0010]

In the method of setting the temperature of the photoconductor film of the image forming apparatus of the present invention, the degree of dark decay in the photoconductor film is first detected when the photoconductor member is mounted. Next, the temperature of the photoconductor film is adjusted according to the detected degree of dark decay of the photoconductor film. Since the temperature of the photoconductor film has a correlation with the degree of dark decay, the dark decay amount can be made constant by adjusting the temperature of the photoconductor film regardless of the type of the photoconductor member.

[0011]

EXAMPLES In the method of setting the temperature of the photoconductor film in the image forming apparatus of the present invention, when a new photoconductor drum is mounted,
After the surface potential of the photoconductor film is detected, the temperature of the photoconductor film is initialized based on the surface potential. As a result, the surface potential of the photoconductor film at the developing position is made constant and an image having a uniform density is formed regardless of the difference in the chargeability and the degree of dark decay of each photoconductor drum.

An example of the present invention will be described below in the case of using a positive charging type single-layer organic photoconductor film as an example.

FIG. 1 shows an image forming apparatus 1 according to an embodiment of the present invention.
It is a systematic diagram which shows the structure of 1. This image forming apparatus 11
1. As shown in FIG. 1, a rotatable photoconductor drum 13 in which a photoconductor film 12 made of a single-layer type organic photoconductor is formed on the surface of a drum substrate 30 made of a metal material such as aluminum, and a photoconductor film. A main charger 14 that uniformly applies a desired amount of electric charge to 12 and an optical device 15 that exposes the photoconductor film 12 to generate light for forming an electrostatic latent image on the photoconductor film 12 and a photoconductor film. A developing device 16 for developing the electrostatic latent image on the recording medium 12 with toner, and a toner image on the photosensitive drum 13 on the recording paper 17
A transfer device 18 for transferring the toner image, a cleaning device 19 for removing the toner remaining on the photosensitive drum 13 after the transfer of the toner image, and an electric charge remaining on the photosensitive drum 13 for removing the photosensitive material. A static elimination lamp 20 for equalizing the potential on the body membrane 12 to a predetermined potential is provided.

The main charger 14 employs a scorotron charger, and has a discharge wire 21 for corona discharge, a shield case 22 surrounding the discharge wire 21, and a shield case 22 open to the photosensitive drum 13 side. And a metal grid 23 provided in the opening. A power supply 25 for supplying a current required for corona discharge is connected to the discharge wire 21 of the main charger 14.
The shield case 22 is grounded.

In this embodiment, as the main charger 14,
By using the scorotron charger, the surface potential at the charging position of the photosensitive drum 13 at the time of charging is
It reaches a predetermined upper limit value and is held at the upper limit value. This is for the following reason. The power supply current Icc from the power supply 25 to the discharge wire 21 is the discharge current Isc to the shield case 22, the discharge current Igc to the grid 23, and the discharge current Ipc to the photosensitive drum 13 due to the discharge.
Will be diverted to. In order for the discharge current from the discharge wire 21 to reach the surface of the photoconductor film 12 via the grid 23,
It is necessary that the surface potential of the photosensitive film 12 is lower than the potential of the grid 23.

When the discharge current Ipc is supplied to the photoconductor film 12 at the charging position by the discharge from the discharge wire 21, the surface potential of the photoconductor film 12 gradually rises. When the rising surface potential matches the potential of the grid 23,
After that, no discharge occurs between the grid 23 and the photoconductor film 12. Power supply current Ic supplied to the discharge wire 21
All of c are discharge currents Isc and Igc. Therefore, the surface potential of the photoconductor film 12 is determined by the grid potential of the grid 23, and is held at the grid potential after reaching the grid potential.

In general, the saturated charging potential Vs of the photosensitive film 12 is
However, it is desirable to carry out main charging so as to be in the range of 500 to 1000 V, particularly 700 to 900 V. Therefore, when performing corona discharge, it is desirable to apply a high voltage of 4 to 7 kV to the discharge wire 21 of the main charger 14.

A surface electrometer 26 for measuring the surface potential is disposed between the charging position of the main charger 14 and the developing position of the photosensitive drum 13 without hindering the rotation of the photosensitive drum 13. Has been done.

The photoconductor film 12 is formed on the inner surface of the drum substrate 30.
A heater 24 made of a planar heating element for increasing the temperature is provided.

FIG. 2 is a system diagram showing the arrangement of the photoconductor drum 13, the main charger 14, the developing device 16, and the charge eliminating lamp 20 of this embodiment, and FIG. 3 shows the grid 23 of the main charger 14. It is a top view. Charger width W1 of the main charger 14
Is, for example, 22 mm, and the opening width W of the grid 23 is
2 is 16 mm as an example. The distance L1 between the grid 23 and the photoconductor drum 13 is 1.5 mm as an example. An angle θ1 between the downstream end of the main charger 14 with respect to the rotation direction of the photoconductor drum 13 and the developing device 16 along the rotation direction is 120 ° as an example.
An angle θ2 along the rotation direction between the main charger 14 and the upstream end of the main charger 14 in the rotation direction is 30 °, for example. The diameter of the photosensitive drum 13 is, for example, φ100 mm. The grid length L2 of the grid 23 is 320 as an example.
mm. The openings of the grid 23 are formed in a mesh shape, and the opening ratio is 80% as an example.

The optical device 15 used for image exposure is
An optical system including a lens or a reflecting mirror, or a laser light oscillator is used. The developing device 16 includes a developing roller 16 a that supplies the charged toner of the one-component developer or the two-component developer to the surface of the photoconductor film 12. As the transfer device 18, a corona charger similar to the main charger 14 or a contact type charger is used.

In the present embodiment, the amount of static elimination light of the static elimination lamp 20 is such that the charging potential of the photoconductor film 12 drops to near zero potential of 100 V or less.
When the i photoconductor film is used, it is preferable that the photoconductor film 12 has a thickness of 1.0 LUX · SEC or more, particularly 1.5 LUX · SEC or more. On the other hand, if 100LUX SEC or more,
Deterioration of quality occurs due to light fatigue of the photoconductor film 12. As the static elimination lamp 20, any visible light source such as a halogen lamp, a fluorescent lamp, a cold cathode ray tube, or a neon lamp such as red or green can be used. Alternatively, a monochromatic light source such as an LED (light emitting diode) of red, yellow, green or the like can be used.

As the photosensitive film 12 of this embodiment, either an inorganic material or an organic material may be used, and the material is not limited.

An aluminum tube is generally used as the conductive drum body 30 of the photosensitive drum 12.

Below, referring to the flow chart,
The operation of this embodiment will be described.

FIG. 4 is a flow chart showing a method of setting the temperature of the photoconductor film in the image forming apparatus 11 of this embodiment. The surface potential detecting operation and the correcting operation for making the surface potential constant at the charging position in this embodiment will be described in detail based on this flowchart.

A new photosensitive drum 1 is provided in the image forming apparatus 11.
3 is mounted, in step a1 of FIG. 4,
The main switch is turned on. In step a2,
The photoconductor drum 13 starts rotating, and the main charger 14 is supplied with the discharge current Icc from the power supply 25. Optical device 15,
The developing device 16, the transfer device 18, the cleaning device 19, the discharge lamp 20 and the like are all stopped. However, when an amorphous Si photoconductor film is used as the photoconductor film 12,
Since the state of the photoconductor film 12 may be different from the state during the normal copying operation due to the heat generated by turning on the other members, it is better to turn on the other members as well. In step a3, the process stands by until the photosensitive drum 13 makes one rotation (for example, about 1 to 6 seconds). The waiting time may be a time in which the photosensitive drum 13 rotates at least once. The measurement of this waiting period is performed by the image forming apparatus 1 of this embodiment.
When one main motor is pulse-driven, it may be realized by counting the pulses used for driving this main motor. In addition, the image forming apparatus 11
However, a timer or a counter may be separately used for measuring the waiting period.

The waiting period is set in order to wait until the charging of the entire surface of the photosensitive film 12 is completed. As described above, when the photosensitive drum 13 is charged by the main charger 14 including a scorotron,
This is because the entire surface of the photoconductor film 12 may not be charged to the saturated charging potential Vs.

Next, in step a4, the surface potential meter 26 measures the surface potential. Step a5
Then, it is judged whether the surface potential measured by the comparator 27 is equal to a predetermined reference value of the surface potential.

Here, the reference value of the surface potential will be described. The dark decay curve is shown in FIG. As can be seen from the figure, the surface potential decreases at a constant rate as time passes after the photoconductor film 12 is charged. In the case of this embodiment, since the scorotron charging is adopted, the surface potential at the charging position is always constant. Therefore, if the target surface potential at the developing position is set, the surface potential at the set position of the surface electrometer 26 required to achieve the target surface potential can be obtained. The obtained surface potential is used as a reference value. For example, when the target surface potential is V0, the reference value of the surface potential is obtained from line A as VA. Therefore,
The setting position of the surface potential meter 26 may be between the charging position and the developing position, and the reference value of the surface potential differs depending on the setting value.

If the determination in step a5 is negative, in step a6, the temperature setting operation of the photosensitive film 12 described below is executed.

First, the principle that the surface potential variation due to the photoconductor film 12 can be compensated by adjusting the temperature of the photoconductor film 12 will be described.

FIG. 6 shows the relationship between the temperature of the photosensitive film 12 and the amount of dark attenuation. In the figure, line D and line E are photoconductor drums D using an amorphous Si photoconductor film, respectively.
And E are shown. As can be seen from the figure, as the temperature of the photoconductor film 12 increases, the amount of dark attenuation also increases, and its characteristics differ depending on the type of the photoconductor film 12. As described above, in this embodiment, since scorotron charging is adopted, the surface potential at the charging position is always constant. Therefore, the dark attenuation amount of the photoconductor film 12 may be controlled so as to match the difference between the surface potential at the charging position and the target surface potential. That is, the measured value of the surface potential is VB (<V
In the case of A), the surface potential at the developing position becomes lower than the target surface potential as shown by the line B in FIG.
In order to reduce the dark attenuation amount to a predetermined value, the initial setting temperature of the photoconductor film 12 is determined to be lower than the current temperature. On the contrary, when the measured surface potential is VC (> VA), the surface potential at the developing position becomes higher than the target surface potential as shown by the line C in FIG. In order to obtain a predetermined value, the initial setting temperature of the photoconductor film 12 is determined to be higher than the current temperature. The temperature of the photosensitive film 12 is adjusted by the heater 24, for example, by adjusting the drive voltage of the heater 24.

However, as can be seen from FIG. 6, the photoconductor film 12 has different characteristics depending on its type, or even if it is the same type, depending on the machine conditions. Therefore, the surface potential may not match the reference value due to the one-time correction operation. That is, when it is desired to set the dark attenuation amount to a predetermined value, the drum temperature to be set differs between the drum D and the drum E. Therefore, the drum temperature is determined based on a general characteristic curve and set to that temperature. After that, the process returns to step a4 again, the surface potential is measured, and it is determined in step a5 whether the measured value of the surface potential matches the reference value. If they do not match, the above correction operation is performed again in step a6. This process is repeated until the measured value of the surface potential matches the reference value.

In this way, the surface potential at the developing position matches the target value. Therefore, even if there is a difference in the charging ability and the degree of dark decay depending on the individual photoconductor film, the temperature of the photoconductor film 12 is adjusted according to the difference, so that the surface potential of the photoconductor film 12 is changed. Variations can be compensated. Thereby, a uniform image density can be realized.

After the operation of setting the initial set temperature is completed, the main switch is cut off in step a7, and the temperature setting of the photosensitive film 12 is completed.

If the determination is affirmative in step a5, the set temperature at that time is optimum, so step a
At 7, the main switch is cut off, and the photoconductor film 12
The temperature setting of is completed.

Conventionally, a heater has been installed in the photosensitive drum 13, but this prevents dew condensation on the photosensitive drum 13 by maintaining the temperature of the photosensitive drum 13 at around 35 degrees. This is because In the photoconductor drum 13 of the image forming apparatus 11 as an electrostatic copying machine, due to dew condensation on the surface of the photoconductor drum 13, the charge distributed on the photoconductor drum 13 disappears or the formed electrostatic charge is lost. This is because the latent image may be destroyed. However, such temperature adjustment is not performed according to the type of the photoconductor film 12 or the like.

In the above embodiment, the degree of dark decay is detected by the charging position of the main charger 14 and the photosensitive drum 13.
The measurement is performed by measuring the surface potential between the developing position and the developing position. However, the device and method for detecting the degree of dark decay are not particularly limited, and other devices and methods capable of detecting the degree of dark decay may be used. For example, a detector for taking out a leak current Ilc generated by dark decay in the photoconductor film 12 is connected to the photoconductor drum 13, and the degree of dark decay is determined from the amount of fluctuation of the leak current Ilc detected by the detector. May be detected.

In the above embodiments, the drum-shaped substrate on which the photosensitive film is formed is used as the photosensitive member.
A belt-shaped substrate on which a photosensitive film is formed may be used.

Although the image forming apparatus of the present invention has been described as an electrostatic copying machine in the above embodiments, the image forming apparatus of the present invention forms an image by an electrophotographic method regardless of the electrostatic copying machine. Any image forming apparatus may be used.

[0042]

According to the present invention, when a new photoconductor drum is mounted, the surface potential of the photoconductor drum is detected, and then the temperature of the photoconductor film 12 is set to an initial set temperature based on the detection result. . As a result, even when a photoconductor film having a different dark decay is used, a stable image can be always formed by keeping the surface potential constant at the developing position.

[Brief description of drawings]

FIG. 1 is a system diagram of an image forming apparatus 11 according to an exemplary embodiment of the present invention.

FIG. 2 is a system diagram showing an arrangement state of the present embodiment.

FIG. 3 is a plan view of a grid 23 of the main charger 14.

FIG. 4 is a flowchart illustrating the operation of this embodiment.

FIG. 5 is a graph showing a dark decay curve.

FIG. 6 is a graph showing the relationship between the temperature of the photoconductor film 12 and the amount of dark attenuation.

FIG. 7 is a system diagram of a conventional image forming apparatus 1.

[Explanation of symbols]

 Reference Signs List 11 image forming apparatus 12 photoconductor film 13 photoconductor drum 14 main charger 16 developing device 19 cleaning device 20 discharge lamp 21 discharge wire 22 shield case 23 grid 24 heater 25 power supply 26 surface potential meter 30 drum base

Claims (1)

[Claims] 1. A photoconductor member having a photoconductor film, charging means for charging the photoconductor film, exposure means for irradiating the charged photoconductor film with light, and developing the exposed photoconductor film. A method for setting the temperature of a photoconductor film in an image forming apparatus equipped with a developing means for detecting the degree of dark decay in the photoconductor film when the photoconductor member is mounted. And a step of adjusting the temperature of the photoconductor film based on the degree of the dark decay so as to make the dark decay amount constant regardless of the type of the photoconductor member. Method.