JP7027812B2 - Image forming device, image forming method, and program - Google Patents

Description

The present invention relates to an image forming apparatus, an image forming method, and a program.

Conventionally, in an electrophotographic image forming apparatus, there is a step of uniformly charging the surface potential of a photoconductor. During the process, a contact DC charging method is adopted in which a DC voltage is applied to the charging roller to bring the charging roller into contact with the surface of the photoconductor and discharge it to the surface of the photoconductor to charge the photoconductor.
In this contact DC charging method, as the photoconductor is rotated, the film formed on the surface layer surface of the photoconductor is scraped off. Then, as the film thickness becomes thinner, the relationship between the voltage applied to the charging roller and the voltage charged on the surface of the photoconductor changes, and the surface potential of the photoconductor required for image formation cannot be maintained. As a result, the printed image becomes defective, and it is necessary to replace the photoconductor.
Therefore, in order to maintain the surface potential of the photoconductor required for image formation, it is necessary to generate an appropriate charging voltage according to the film thickness, and IV representing the relationship between the charging current I and the charging voltage V in advance. A technique of calculating the characteristics and predicting the film thickness of the photoconductor from the inclination of the IV characteristics is known.
In Patent Document 1, for the purpose of calculating the film thickness of the photoconductor, by using a correction value according to the temperature and humidity, the measurement deviation due to the temperature and humidity is eliminated, and the charging current and the charging voltage at the time of application are shown. A method of calculating a film thickness based on an IV characteristic and adding a correction value to the calculation result is disclosed.

However, in the prior art, there is a problem that the calculation result of the film thickness of the photoconductor is different due to the change in the influence of temperature and humidity.
In Patent Document 1, a correction value is added to the calculation result of the film thickness of the photoconductor. However, the residual potential after static elimination of the photoconductor fluctuates depending on the voltage applied before static elimination and the temperature and humidity environment. As a result, the problem that accurate IV characteristics cannot be obtained has not been solved.
One embodiment of the present invention has been made in view of the above, and an object thereof is to make the residual potential of the photoconductor constant after static elimination.

In order to solve the above problems, the invention according to claim 1 applies a voltage application unit that applies a charging bias to a charging member that charges the peripheral surface of the orbiting photoconductor, and the charging bias applied to the charging member. A current detection unit that generates a feedback signal representing an output current flowing from the charging member to the photoconductor, and a control unit that controls the voltage application unit based on the feedback signal generated by the current detection unit. An image forming apparatus including a static eliminating means for eliminating static electricity from the photoconductor and a temperature detecting unit for detecting an environmental temperature, wherein the control unit sequentially responds to the environmental temperature during one measurement cycle. The voltage application unit is controlled so that the corrected charging voltage is applied to the charging member, the static elimination means is controlled to eliminate static electricity, and the voltage application unit is applied so as to apply the charging bias to the charging member. A measurement cycle control unit that controls and controls the current detection unit to detect the output current when the charging bias is applied to the charging member, and controls the static elimination means to eliminate static electricity, and the measurement cycle. When a plurality of measurement cycles are continuous with respect to the control unit, the output current represented by the feedback signal and the charging bias applied by the voltage application unit are configured in each measurement cycle. It is characterized by including a charge bias control unit that controls the charge bias differently in order to derive V characteristics .

According to the present invention, the residual potential of the photoconductor after static elimination can be made constant.

It is a figure which shows the whole structure of the electrophotographic process adopted in the general image forming apparatus. It is a figure which shows the whole structure of the electrophotographic process adopted in the image forming apparatus which concerns on 1st Embodiment of this invention. It is a graph which shows the IV characteristic described in Patent Document 2. FIG. It is a graph which shows the potential fluctuation and the amount of current when the potential becomes constant after static elimination. (A) is a graph showing the relationship between the charge bias and the surface potential after static elimination, and (b) is a graph showing the relationship between the amount of light irradiated to the photoconductor 1 during static elimination and the residual potential. It is a graph which shows the relationship between the inclination (IV characteristic) and a film thickness under a temperature-humidity environment. It is a graph which shows the current change by the potential fluctuation after static elimination. It is a graph which shows the inclination fluctuation by the potential deviation after static elimination. It is a flowchart of a subroutine which shows the control method by a prior art. It is a graph which shows the application method of the charge voltage by the prior art. It is a functional block diagram which shows the structure of the main part of the image forming apparatus which concerns on 1st Embodiment of this invention. It is a flowchart of the subroutine which shows the control process of the image forming apparatus which concerns on 1st Embodiment of this invention. It is a graph which shows the relationship between the charge voltage of a photoconductor and time. It is a graph which shows the method of applying the charge voltage by the image forming apparatus which concerns on 1st Embodiment of this invention. It is a graph which shows the IV characteristic acquired in the normal temperature and humidity MM environment and the low temperature and low humidity LL environment by using the charging voltage application method shown in FIG. It is a flowchart of the subroutine which shows the control process of the image forming apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the control process of the image forming apparatus which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the control process of the image forming apparatus which concerns on 4th Embodiment of this invention. It is a flowchart which shows the control process of the image forming apparatus 100 which concerns on 5th Embodiment of this invention. It is a figure which shows the value of a constant voltage corresponding to the film thickness of a photoconductor.

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings.
The present invention has the following configuration in order to keep the residual potential of the photoconductor constant after static elimination.
That is, in the image forming apparatus of the present invention, the photoconductor is composed of a voltage application unit that applies a charging bias to the charging member that charges the peripheral surface of the rotating photoconductor, and a charging member that applies the charging bias to the charging member. A current detector that generates a feedback signal that represents the output current flowing through the current, a control unit that controls the voltage application unit based on the feedback signal generated by the current detector, a static elimination means that eliminates static electricity from the photoconductor, and an environmental temperature. It is an image forming apparatus provided with a temperature detecting unit for detecting a current, and the control unit sequentially applies a charging voltage corrected according to the environmental temperature to the charging member during one measurement cycle. Control the application unit, control the static elimination means to eliminate static electricity, control the voltage application unit so that the charging bias is applied to the charging member, and detect the output current when the charging bias is applied to the charging member. When a plurality of measurement cycles are continuous with respect to the measurement cycle control unit that controls the current detection unit and controls the static elimination means to eliminate static electricity , the feedback is given in each measurement cycle. It is provided with a charging bias control unit that controls the charging bias differently in order to derive an IV characteristic composed of the output current represented by the signal and the charging bias applied by the voltage application unit . It is a feature.
By providing the above configuration, the residual potential of the photoconductor after static elimination can be made constant.
The features of the present invention described above will be described in detail with reference to the following drawings. However, unless there is a specific description, the components, types, combinations, shapes, relative arrangements, etc. described in this embodiment are merely explanatory examples, not the purpose of limiting the scope of the present invention to that alone. ..
The above-mentioned features of the present invention will be described in detail below with reference to the drawings.

<First Embodiment>
<General electrophotographic process>
FIG. 1 is a diagram showing an overall configuration of an electrophotographic process adopted in a general image forming apparatus 100.
FIG. 1 shows a configuration of a general direct DC charging type electrophotographic process, which includes a photoconductor 1, a charging roller (charging member) 2, an exposure unit 3, a developing unit 4, a transfer roller 5, a blade 6, and a static eliminator. 7. It includes a high-voltage power supply (charge) 8, an output feedback unit 9 (current detection unit or voltage detection unit), a control unit 10, and an A / D conversion unit 10a.
The photoconductor 1 is circulated, and a high DC voltage generated by the high-voltage power supply 8 is applied to the charging roller (charging member) 2 to uniformly charge the surface of the photoconductor 1. After that, the exposure unit 3 exposes the surface of the photoconductor 1 with the image light corresponding to the image signal, and an electrostatic latent image is formed on the surface of the photoconductor 1.

Then, the electrostatic latent image on the surface of the photoconductor 1 is developed into a toner image by the developing unit 4, and the toner image on the photoconductor 1 is transferred to the recording medium by the transfer roller 5. Then, the image is formed on the recording medium by being fixed by the fixing means.
Further, after removing the electric charge on the surface of the photoconductor 1 by the LED light irradiated by the static eliminator 7, the electric charge processing is performed.
In Patent Document 1, a plurality of different voltages are applied to the photoconductor to be charged by the control of the control unit, the current at the time of application is detected, the IV characteristic is calculated, and the film thickness is calculated from the slope of the characteristic. It is known to detect.

<Electrophotograph process adopted in the image forming apparatus according to the first embodiment>
FIG. 2 is a diagram showing an overall configuration of an electrophotographic process adopted in the image forming apparatus 100 according to the first embodiment of the present invention.
It includes a control unit 10, an A / D conversion unit 10a, a CPU (central processing unit) 10b, a ROM (read only memory) 10c, and a RAM (random access memory) 10d.

<I-V characteristic detection by conventional technology>
Next, the point A (surface potential after static elimination) on the photoconductor 1 after the static elimination by the static eliminator 7 and before the charging bias is applied by the charging roller 2, and after the charging bias is applied by the charging roller 2. The explanation will be given focusing on the point B (surface potential after charging).
In order to derive the IV characteristic at the time of charging, the control unit 10 applies a plurality of different voltages and detects the charging current at that time via the A / D conversion unit 10a.

Suppose that four different voltages are applied in a plurality of control steps as a plurality of different voltages. At this time, the control steps are the following [S1] to [S5].
[S1] The charging voltage of the voltage V1 is applied, and the current I1 at that time is detected.
[S2] A charging voltage of voltage V2 is applied, and the current I2 at that time is detected.
[S3] A charging voltage of voltage V3 is applied, and the current I3 at that time is detected.
[S4] A charging voltage of voltage V4 is applied, and the current I4 at that time is detected.
[S5] The IV characteristics are derived from the applied voltage and the detection current when [S1] to [S4] are executed (see FIG. 3), and the film thickness of the photoconductor 1 is calculated.
The voltages V1 to V4 have different voltage values. It should be noted that the plurality of different voltages may be two or more points.

<IV characteristic graph>
FIG. 3 is a graph showing the IV characteristics described in Patent Document 2.
Patent Document 2 discloses a technique for determining the film thickness of a photoconductor based on the slope of the IV characteristic graph shown in FIG.
Specifically, when the photoconductor 1 is charged via the charging roller (charging member) 2, the current Idc flowing between the charging roller 2 and the photoconductor 1 and the film thickness d of the photosensitive layer of the photoconductor 1 In the meantime, Idc = k / d (K is a constant) holds.
In this method, it is necessary that the potential (point A) after static elimination is constant.

<Potential fluctuation and current amount>
FIG. 4 is a graph showing the potential fluctuation and the amount of current when the potential after static elimination becomes constant.
Points A and B shown in FIG. 4 represent the surface potential of the photoconductor 1, and the arrow toward point B represents the amount of charging current.

<Relationship between charge bias and surface potential after static elimination>
FIG. 5A is a graph showing the relationship between the charge bias and the surface potential after static elimination.
FIG. 5A shows that the potential after static elimination changes depending on the temperature and humidity and the applied voltage, and it does not change so much in a normal temperature and humidity MM environment, but it changes remarkably in a low temperature and low humidity LL environment. Represents. It also shows that there is a difference in residual electrification depending on the environment. It shows the characteristics that do not change so much under the normal temperature and humidity MM environment, but shows that the fluctuation becomes large under the low temperature and low humidity LL environment.
As shown in FIG. 5A, in a normal temperature and humidity MM environment, a residual potential of 19V remains when 900V is applied to the photoconductor 1 as a charging bias and then static electricity is removed. Next, when 1000 V is applied and then static elimination occurs, a residual potential of 20 V remains, and a tilt deviation of 1 V occurs.
Next, when static electricity is removed after applying 1100 V, a residual potential of 21 V remains, and a tilt deviation of 2 V occurs. Next, when 1200 V is applied and then static elimination occurs, a residual potential of 22 V remains, and a tilt deviation of 3 V occurs.

On the other hand, in a low temperature and low humidity LL environment, a residual potential of 75 V remains when 900 V is applied to the photoconductor 1 as a charging bias and then static elimination is performed. Next, when 1000 V is applied and then static elimination is performed, a residual potential remains at 82 V, and a tilt deviation of 7 V occurs.
Next, when static electricity is removed after applying 1100 V, a residual potential remains at 84 V, and a tilt deviation of 9 V occurs. Next, when the charge is removed after applying 1200 V, the residual potential remains at 88 V, and a tilt deviation of 13 V occurs.
As described above, the potential (point A) after static elimination fluctuates depending on the temperature and humidity under the low temperature and low humidity LL environment and the normal temperature and normal humidity MM environment, and is not constant. Further, it varies depending on the voltage applied to the photoconductor 1, and is not constant.

<Relationship between light intensity and residual potential>
FIG. 5B is a graph showing the relationship between the amount of light applied to the photoconductor 1 during static elimination and the residual potential.
At the time of static elimination, the LED light is irradiated from the static eliminator 7 to the photoconductor 1.
As shown in FIG. 5B, the relationship between the amount of light applied to the photoconductor 1 and the residual potential during static elimination is such that the higher the amount of light, the lower the residual potential, and the lower the amount of light, the higher the residual potential. Therefore, in order to make the residual potential 0V, it is necessary to make the irradiation time extremely long, which is difficult in mounting. Further, as the amount of light is increased, the photoconductor 1 is damaged. Therefore, the residual potential after static elimination does not reach 0V.

<Relationship between inclination and film thickness in temperature and humidity environment>
FIG. 6 is a graph showing the relationship between the inclination (IV characteristic) and the film thickness in a temperature / humidity environment.
In the prior art, it is ideal that the relationship between the film thickness and the inclination is constant. However, due to the problem described with reference to FIG. 5 (a), as shown in FIG. 6, in a low temperature and low humidity LL environment (for example, 10 ° C., 15%), a normal temperature and normal humidity MM environment (for example, 23). ° C., 50%), indicating that the error is larger than that in a high temperature and high humidity HH environment (for example, 27 ° C., 80%).
That is, from the two points of the relationship between the charging bias shown in FIG. 5A and the surface potential after static elimination, and the relationship between the inclination (IV characteristic) and the film thickness in the temperature and humidity environment shown in FIG. It can be understood that the fact that the potential after static elimination is always constant as shown in FIG. 4 does not hold.
The film thickness of the photoconductor is about 34 um when it is new, and the film thickness that is determined to require replacement is 13 um.

<Current change due to potential fluctuation after static elimination>
FIG. 7 is a graph showing a current change due to a potential fluctuation after static elimination.
The arrow for each point A shown in FIG. 7 represents the amount of voltage movement, and the amount of current is proportional to the amount of movement. Originally, the current required to derive the IV characteristic is the current indicated by the left arrow with respect to point A shown in FIG. 7. That is, it is a charging current when the potential at point A after static elimination is constant.
However, the potential after static elimination fluctuates as shown by the arrow on the right side under the temperature and humidity environment and the applied potential difference.
That is, it can be understood that the difference between the left arrow (voltage at the time of application) and the right arrow (voltage after static elimination) becomes an error ΔV, the charging current value fluctuates, and the I / V characteristics change.

<Inclination fluctuation due to potential shift after static elimination>
FIG. 8 is a graph showing tilt fluctuation due to potential deviation after static elimination.
The slope α1 shown in FIG. 8 is an I / V characteristic shown by the original ideal slope, and the slope α2 is a slope that has changed due to the fact that the potential after static elimination is not constant. Therefore, when the inclination α2 is used, there is a problem that the film thickness of the photoconductor 1 cannot be calculated accurately.
Since the residual potential after static elimination is different between the low temperature and low humidity LL environment and the high temperature and high humidity HH environment, a calculation error of about 1 um occurs in the film thickness obtained from the slope of the IV characteristic.

<Control method by conventional technology>
FIG. 9 is a flowchart of a subroutine showing a control method according to the prior art.
Step S10 is a charging IV characteristic detection control process used in the prior art.
First, in step S15, the variable N is reset so that N = 1.
In step S20, a charging voltage (a * N + b) is applied. Note that a and b are coefficients.
In step S25, the current I is detected in a predetermined sampling cycle.
In step S30, the photoconductor 1 is rotated once, and the surface of the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
In step S35, the variable N is counted up (N = N + 1).
In step S40, it is determined whether or not the count number of the variable N is 4 or more. If the variable N is smaller than 4, the process returns to step S20, and if the variable N is 4 or more, the process proceeds to step S45.
In step S45, the IV characteristic is derived based on the applied voltage V and the detected current I, the charging IV characteristic detection control process is terminated, and the process returns to the main routine.

<Method of applying charging voltage by conventional technology>
FIG. 10 is a graph showing a method of applying a charging voltage according to the prior art.
[1] At time t1, a charging voltage V1 is applied to the photoconductor 1, and the current I1 at that time is detected via the A / D conversion unit 10a.
[2] At time t2, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[3] At time t3, a charging voltage V2 is applied to the photoconductor 1, and the current I2 at that time is detected via the A / D conversion unit 10a.
[4] At time t4, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[5] At time t5, a charging voltage V3 is applied to the photoconductor 1, and the current I3 at that time is detected via the A / D conversion unit 10a.
[6] At time t6, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[7] At time t7, a charging voltage V4 is applied to the photoconductor 1, and the current I4 at that time is detected via the A / D conversion unit 10a.
[8] At time t8, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[9] Based on the charging voltages V1 to V4 and the detected currents I1 to I4, the slope of the I / V characteristic is calculated to calculate the film thickness of the photoconductor 1.

<First Embodiment>
FIG. 11 is a functional block diagram showing a configuration of a main part of the image forming apparatus 100 according to the first embodiment of the present invention.
The image forming apparatus 100 includes a control unit 20, a photoconductor drive unit 21, a charging unit 22, an exposure unit 3, a developing unit 4, a transfer unit 23, a static eliminator 7, a storage unit 24, and a temperature detection unit 25 as functional blocks. I have.
The image forming apparatus 100 includes a control unit 20 as a functional block of the control unit 10 shown in FIG.
As described above, the control unit 10 shown in FIG. 2 is composed of, for example, a microcomputer having a CPU 10b, a ROM 10c, and a RAM 10d.
The CPU 10b reads the operating system OS from the ROM 10c, expands it on the RAM 10d, starts the OS, reads the application software program (processing module) from the ROM 10c under OS management, and executes various processes. The control unit 20 shown in 11 is realized.
The control unit 20 controls the voltage application unit 22a based on the feedback signal generated by the current detection unit 22b via the A / D conversion unit 10a. Inside the control unit 20, software modules such as a drive control unit 20a, a measurement cycle control unit 20b, a charge bias control unit 20c, a determination unit 20d, a film thickness calculation unit 20e, and a photoconductor life determination unit 20f are programmed. I have.

The drive control unit 20a controls the rotation of the photoconductor drive unit 21.
The measurement cycle control unit 20b controls the voltage application unit 22a so as to sequentially apply a constant charging voltage Vk to the charging roller 2 during one measurement cycle, and controls the static eliminator 7 to eliminate static electricity. The voltage application unit 22a is controlled so that the charging bias is applied to the charging roller 2, and the current detection unit 22b is controlled so that the current when the charging bias is applied is detected via the A / D conversion unit 10a. The electric device 7 is controlled to eliminate static electricity.
The measurement cycle control unit 20b determines whether or not the detected residual voltage exceeds the threshold value, and if the residual voltage does not exceed the threshold value, the voltage application unit 22a applies a constant charging voltage Vk to the charging roller 2. Skip the applied operation.

The charge bias control unit 20c controls the measurement cycle control unit 20b so that the charge bias in each measurement cycle is different when a plurality of measurement cycles are continuous.
The charge bias control unit 20c controls the measurement cycle control unit 20b so that when a plurality of measurement cycles are continuous, the charge bias in the subsequent measurement cycle is sequentially higher than the preceding measurement cycle. Further, the charge bias control unit 20c controls the measurement cycle control unit 20b so that the charge bias in the subsequent measurement cycle is sequentially lower than the preceding measurement cycle when a plurality of measurement cycles are continuous.
The charge bias control unit 20c controls so that the charge bias is optimized according to the film thickness of the photoconductor 1 calculated by the film thickness calculation unit 20e.

The determination unit 20d determines whether or not to execute the control.
The film thickness calculation unit 20e calculates the film thickness of the photoconductor 1 based on the slope of the IV characteristic composed of the output current represented by the feedback signal and the charging voltage applied by the voltage application unit 22a. The film thickness calculation unit 20e calculates the slope of the IV characteristic composed of the charging voltage applied by the voltage application unit 22a and the output current represented by the feedback signal, and corresponds to the slope from the data table of the storage unit 24. Calculate the film thickness.
The photoconductor life determination unit 20f determines the optimum life of the photoconductor 1 based on the film thickness of the photoconductor 1 calculated by the film thickness calculation unit 20e.

The photoconductor drive unit 21 rotates the motor under the control of the drive control unit 20a to rotate the photoconductor 1.
The charging unit 22 includes a voltage application unit 22a, a current detection unit 22b, and a voltage detection unit 22c.
The voltage application unit 22a applies a charging bias to the charging roller 2 that charges the peripheral surface of the orbiting photoconductor 1.
The current detection unit 22b detects the output current flowing from the charging roller 2 to the photoconductor 1 via the A / D conversion unit 10a and generates a feedback signal.
After starting the static eliminator 7, the voltage detection unit 22c detects the residual voltage remaining in the photoconductor 1 via the A / D conversion unit 10a.

The exposure unit 3 exposes the surface of the photoconductor 1.
The developing unit 4 charges the toner and develops the toner image on the surface of the photoconductor 1.
The transfer unit 23 includes a voltage application unit 23a and a roller drive unit 23b, and transfers a toner image to a recording medium.
The voltage application unit 23a applies a transfer voltage to the transfer roller 5 to transfer the toner image on the surface of the photoconductor 1 to the recording medium.
The roller drive unit 23b rotates the motor under the control of the drive control unit 20a to rotate the transfer roller 5, and the toner image on the photoconductor 1 is transferred to the recording medium.
The static eliminator 7 irradiates the surface of the photoconductor 1 with LED light to eliminate the potential applied to the surface of the photoconductor 1.
The storage unit 24 stores in advance a data table showing the relationship between the IV characteristics and the film thickness. As a result, the slope related to the IV characteristic composed of the applied charging voltage and the output current is calculated, and the film thickness corresponding to the slope calculated from the data table is calculated, so that the calculation at the time of film thickness detection is performed. The load can be reduced.
The temperature detection unit 25 detects the environmental temperature.

<Relationship between charging voltage of photoconductor and time>
In the embodiment of the present invention, in order to solve the problem shown in FIG. 8, the potential after static elimination is applied by applying a constant charging voltage Vk before applying the voltage V4 from the applied voltage V1 for deriving the I / V characteristics. It is possible to suppress the variation.
The constant charging voltage Vk is a voltage that is equal to or higher than the voltage at which the photoconductor 1 can be charged and the voltage fatigue of the photoconductor 1 due to application is small, and is, for example, 400 V to 800 V.

<Control process 1>
FIG. 12 is a flowchart of a subroutine showing a control process of the image forming apparatus 100 according to the first embodiment of the present invention.
Step S100 is the charging IV characteristic detection control process used in the first embodiment.
First, in step S15, the measurement cycle control unit 20b resets the variable N so that N = 1.
In step S105, the measurement cycle control unit 20b controls the voltage application unit 22a and applies a constant charging voltage Vk to the photoconductor 1.
In step S110, the measurement cycle control unit 20b controls the photoconductor drive unit 21 to rotate the photoconductor 1 once, and the measurement cycle control unit 20b controls the static eliminator 7 and LED light from the static eliminator 7. Is applied to the photoconductor 1 to eliminate static electricity.
In step S20, the measurement cycle control unit 20b controls the voltage application unit 22a and applies the charging voltage (a * N + b). Note that a and b are coefficients.

In step S25, the measurement cycle control unit 20b controls the current detection unit 22b and detects the current I via the A / D conversion unit 10a in a predetermined sampling cycle. Almost at the same time, the measurement cycle control unit 20b controls the voltage detection unit 22c and detects the voltage V via the A / D conversion unit 10a in a predetermined sampling cycle.
In step S30, the measurement cycle control unit 20b controls the photoconductor drive unit 21 to rotate the photoconductor 1 once, and the measurement cycle control unit 20b controls the static eliminator 7 and LED light from the static eliminator 7. Is applied to the photoconductor 1 to eliminate static electricity.
In step S35, the measurement cycle control unit 20b counts up the variable N (N = N + 1).
In step S40, the measurement cycle control unit 20b determines whether or not the count number of the variable N is 4 or more. If the variable N is smaller than 4, the process returns to step S105, and if the variable N is 4 or more, the process proceeds to step S45.
In step S45, the measurement cycle control unit 20b derives the IV characteristic based on the applied voltage V and the detected current I, ends the charging IV characteristic detection control process, and returns to the main routine.

As a result, the voltage application unit 22a is controlled so that a constant charging voltage Vk is sequentially applied to the charging roller 2 during one measurement cycle, the static eliminator 7 is controlled to eliminate static electricity, and the charging bias is charged. The voltage application unit 22a is controlled so as to be applied to the roller 2, the current detection unit 22b is controlled to detect the current when the charging bias is applied, and the static eliminator 7 is controlled to eliminate static electricity. The residual potential of the subsequent photoconductor 1 can be made constant.
Moreover, when a plurality of measurement cycles are continuous, the residual potential of the photoconductor 1 after static elimination becomes constant by controlling the measurement cycle control unit 20b so that the charging bias in each measurement cycle is different. After that, the voltage of the charging bias applied with high accuracy and the current when the charging bias is applied can be detected.

Further, when a plurality of measurement cycles are continuous, the charge bias in the subsequent measurement cycle may be controlled to be sequentially higher than the preceding measurement cycle, and the voltage of the charge bias applied with high accuracy and the charge bias may be applied. It is possible to detect the current when the voltage is applied.
Further, when a plurality of measurement cycles are continuous, the charge bias in the subsequent measurement cycle may be controlled to be sequentially lower than the preceding measurement cycle, and the voltage of the charge bias applied with high accuracy and the charge bias may be applied. It is possible to detect the current when the voltage is applied.
From the above, the slope of the charged IV characteristic can be calculated accurately.

FIG. 13 is a graph showing the relationship between the charging voltage of the photoconductor 1 and time.
[1] A constant charging voltage Vk is applied to the photoconductor 1 between times t1 and t2.
[2] A charging voltage V1 is applied to the photoconductor 1 between times t2 and t3, and the current I1 at that time is detected via the A / D conversion unit 10a. Almost at the same time, the voltage V2 is detected via the A / D conversion unit 10a.
[3] A constant charging voltage Vk is applied to the photoconductor 1 between times t3 and t4.
[4] A charging voltage V2 is applied to the photoconductor 1 between times t4 and t5, and the current I2 at that time is detected via the A / D conversion unit 10a. Almost at the same time, the voltage V2 is detected via the A / D conversion unit 10a.
[5] A constant charging voltage Vk is applied to the photoconductor 1 between times t5 and t6.
[6] A charging voltage V3 is applied to the photoconductor 1 between times t6 and t7, and the current I3 at that time is detected via the A / D conversion unit 10a. Almost at the same time, the voltage V3 is detected via the A / D conversion unit 10a.
[7] A constant charging voltage Vk is applied to the photoconductor 1 between times t7 and t8.
[8] A charging voltage V4 is applied to the photoconductor 1 between times t8 and t9, and the current I4 at that time is detected via the A / D conversion unit 10a. Almost at the same time, the voltage V4 is detected via the A / D conversion unit 10a.
[9] Based on the charging voltages V1 to V4 and the detected currents I1 to I4, the slope of the I / V characteristic is calculated to calculate the film thickness of the photoconductor 1.

<Method of applying charging voltage by the image forming apparatus of the present invention>
FIG. 14 is a graph showing a method of applying a charging voltage by the image forming apparatus 100 according to the first embodiment of the present invention.
[1] At time t1, a constant charging voltage Vk is applied to the photoconductor 1.
[2] At time t2, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[3] At time t3, a charging voltage V1 is applied to the photoconductor 1, and the current I1 at that time is detected via the A / D conversion unit 10a.
[4] At time t4, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[5] At time t5, a constant charging voltage Vk is applied to the photoconductor 1.
[6] At time t6, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[7] At time t7, a charging voltage V2 is applied to the photoconductor 1, and the current I2 at that time is detected via the A / D conversion unit 10a.
[8] At time t8, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[9] At time t9, a constant charging voltage Vk is applied to the photoconductor 1.
[10] At time t10, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.

[11] At time t11, a charging voltage V3 is applied to the photoconductor 1, and the current I3 at that time is detected via the A / D conversion unit 10a.
[12] At time t12, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[13] At time t13, a constant charging voltage Vk is applied to the photoconductor 1.
[14] At time t14, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[15] At time t15, a charging voltage V4 is applied to the photoconductor 1, and the current I4 at that time is detected via the A / D conversion unit 10a.
[16] At time t16, the photoconductor 1 is irradiated with LED light from the static eliminator 7 to eliminate static electricity.
[17] Based on the charging voltages V1 to V4 and the detected currents I1 to I4, the slope of the I / V characteristic is calculated to calculate the film thickness of the photoconductor 1.

Here, the current flowing from the photoconductor 1 to the charging roller (charging member) 2 when the charging voltage is applied will be described.
The charging current Idc is calculated by the capacity C0 per unit area of the photoconductor 1, the length L of the photoconductor 1, the linear velocity λ, the voltage Vd after charging of the photoconductor 1, and the voltage Vd0 before charging of the photoconductor 1. .. The calculation formula (1) of the charging current Idc is
Idc = C0 * L * λ * (Vd-Vd0) (1)
Will be.
The charging currents Id1 and Id2 applied to calculate the slope α of the IV characteristic are
Id1 = C0 * L * λ * (Vd1-Vd01) (2)
Id2 = C0 * L * λ * (Vd1-Vd02) (3)
Will be.

Equation (4) for calculating the slope α is
α = (Id2-Id1) / (Vd2-Vd1)
= C0 * L * λ * (Vd2-Vd1) / (Vd2-Vd1)
= {C0 * L * λ * (Vd2-Vd02) -C0 * L * λ * (Vd1-Vd01)} / (Vd2-Vd1)
= {(C0 * L * λ * Vd2-C0 * L * λ * Vd02)
-(C0 * L * λ * Vd1-C0 * L * λ * Vd01) / (Vd2-Vd1) (4)

Therefore, by keeping the potential (Vd0) after static elimination constant,
α = {(C0 * L * λ * Vd2)-(C0 * L * λ * Vd1)} / (Vd2-Vd1)
α = (Id2-Id1) / (Vd2-Vd1) = C0 * L * λ
Is true.
Therefore, by keeping the potential after static elimination constant, a constant inclination can be obtained regardless of the temperature and humidity.
In short, even if the temperature / humidity environment changes and the potential after static elimination changes, if the potential is constant until the IV characteristic is calculated, the slope α indicated by the IV characteristic is constant.

<IV characteristics acquired under normal temperature and humidity MM environment and low temperature and low humidity LL environment>
FIG. 15 is a graph showing the IV characteristics acquired under the normal temperature and humidity MM environment and the low temperature and low humidity LL environment by using the charging voltage application method shown in FIG.
As shown in FIG. 12, a comparison between the case where the slope α _MM is calculated from the IV characteristics under a normal temperature and humidity MM environment and the case where the slope α _LL is calculated from the IV characteristics under a low temperature and low humidity LL environment is compared. , It can be confirmed that both are parallel.

<Second Embodiment>
<Control process 2>
FIG. 16 is a flowchart of a subroutine showing a control process of the image forming apparatus 100 according to the second embodiment of the present invention.
Step S200 is the charging IV characteristic detection control process used in the second embodiment.
First, in step S15, the measurement cycle control unit 20b resets the variable N so that N = 1.
In step S205, the measurement cycle control unit 20b measures the potential at point A after static elimination.
In step S210, the measurement cycle control unit 20b determines whether or not the potential at point A is equal to or greater than the threshold value. If the potential at point A is equal to or higher than the threshold value, the process proceeds to step S105, while if the potential at point A is less than the threshold value, the process proceeds to step S25.
Since steps S105, S110, and S20 are the same as those in the first embodiment, the description thereof will be omitted.

In step S105, the measurement cycle control unit 20b controls the voltage application unit 22a and applies a constant charging voltage Vk to the photoconductor 1.
In step S110, the measurement cycle control unit 20b controls the photoconductor drive unit 21 to rotate the photoconductor 1 once, and the measurement cycle control unit 20b controls the static eliminator 7 and LED light from the static eliminator 7. Is applied to the photoconductor 1 to eliminate static electricity.
Since steps S25 to S35 are the same as those in the first embodiment, the description thereof will be omitted.
In step S40, the measurement cycle control unit 20b determines whether or not the count number of the variable N is 4 or more. If the variable N is smaller than 4, the process returns to step S105, and if the variable N is 4 or more, the process proceeds to step S45.
In step S45, the measurement cycle control unit 20b derives the IV characteristic based on the applied voltage V and the detected current I, ends the charging IV characteristic detection control process, and returns to the main routine.

As a result, when the detected residual voltage does not exceed the threshold value, the control time can be shortened by skipping the operation of applying a constant charging voltage Vk to the charging roller 2.

<Measurement cycle control unit>
In step S105 described above, the measurement cycle control unit 20b is designed to apply a constant charging voltage Vk to the photoconductor 1, but the present invention is not limited to this point.
That is, the image forming apparatus 100 may include a temperature detection unit 25 for detecting the environmental temperature, and the measurement cycle control unit 20b may be configured to correct a constant charging voltage Vk according to the environmental temperature.
For example, in a low temperature and low humidity LL environment, the potential after static elimination becomes high, so LL: Vk = 900V, MM: Vk = 1000V, and HH: Vk = 1100V, which are constant voltages.
Alternatively, since the potential after static elimination is high in a low temperature and low humidity LL environment, LL: Vk = 900V, and since the potential after static elimination does not change much in a normal temperature and humidity MM environment and a high temperature and high humidity HH environment, MM: Vk. = 1000V, HH: Vk = 1000V may be used.
As a result, the residual potential of the photoconductor 1 after static elimination can be made constant by correcting the constant charging voltage Vk according to the environmental temperature.

<Third Embodiment>
<Control process 3>
FIG. 17 is a flowchart showing a control process of the image forming apparatus 100 according to the third embodiment of the present invention.
Step S300 is the control process used in the third embodiment.
In step S305, the measurement cycle control unit 20b calls the subroutine of the charging IV characteristic detection control process [1] or [2] described above.
In step S310, the film thickness calculation unit 20e obtains the film thickness of the photoconductor 1 from the slope of the IV characteristic obtained in step S305, and ends the control.

As a result, the film thickness state of the photoconductor 1 is recognized by calculating the film thickness of the photoconductor 1 based on the slope of the IV characteristic composed of the output current represented by the feedback signal and the applied charging voltage. can do.
From the above, the film thickness can be calculated accurately regardless of the temperature and humidity. Since a thermo-hygrometer is not required to calculate the film thickness, the manufacturing cost can be reduced accordingly.

<Fourth Embodiment>
<Control process 4>
FIG. 18 is a flowchart showing a control process of the image forming apparatus 100 according to the fourth embodiment of the present invention.
Step S400 is the control process used in the fourth embodiment.
Since steps S305 to S310 are the same as those in the third embodiment, the description thereof will be omitted.
In step S405, the photoconductor life determination unit 20f determines whether or not the film thickness of the photoconductor 1 is equal to or less than the threshold value. If the film thickness of the photoconductor 1 is equal to or less than the threshold value, the process proceeds to step S410, while if the film thickness of the photoconductor 1 is larger than the threshold value, the control is terminated.
When the film thickness of the photoconductor 1 is equal to or less than a threshold value (for example, 13 to 14 um), in step S410, the photoconductor life determination unit 20f executes a process when the life of the photoconductor 1 is reached. For example, a message indicating that the life of the photoconductor 1 has been reached is displayed on the display panel. Then, the control is terminated.

As a result, the optimum life of the photoconductor 1 is determined based on the calculated film thickness of the photoconductor 1, so that the life of the photoconductor 1 can be determined according to the individual state of the photoconductor 1, and the estimation method by the prior art is used. The life of the photoconductor 1 can be measured with high accuracy.
As described above, it is possible to grasp the degree of deterioration of the film thickness of the photoconductor 1 and determine the life suitable for each photoconductor 1.

<Fifth Embodiment>
<Control process 5>
FIG. 19 is a flowchart showing a control process of the image forming apparatus 100 according to the fifth embodiment of the present invention.
Step S500 is the control process used in the fifth embodiment.
Since steps S305 to S310 are the same as those in the third embodiment, the description thereof will be omitted.
In step S505, the charge bias control unit 20c determines whether or not the film thickness of the photoconductor 1 is the threshold value 1 or less. If the film thickness of the photoconductor 1 is equal to or less than the threshold value 1, the process proceeds to step S510, while if the film thickness of the photoconductor 1 is larger than the threshold value 1, the process proceeds to step S515.
When the film thickness of the photoconductor 1 is equal to or less than the threshold value 1, in step S510, the charge bias control unit 20c determines the applied voltage of charge to _VA .
When the film thickness of the photoconductor 1 is larger than the threshold value 1, in step S515, the charge bias control unit 20c determines whether or not the film thickness of the photoconductor 1 is equal to or less than the threshold value 2. If the film thickness of the photoconductor 1 is equal to or less than the threshold value 2, the process proceeds to step S520, while if the film thickness of the photoconductor 1 is larger than the threshold value 2, the process proceeds to step S525.
When the film thickness of the photoconductor 1 is equal to or less than the threshold value 2, in step S520, the charge bias control unit 20c determines the applied voltage of charge to V _B.

When the film thickness of the photoconductor 1 is larger than the threshold value 2, in step S525, the charge bias control unit 20c determines whether or not the film thickness of the photoconductor 1 is the threshold value 3 or less. If the film thickness of the photoconductor 1 is equal to or less than the threshold value 3, the process proceeds to step S530, while if the film thickness of the photoconductor 1 is larger than the threshold value 3, the process proceeds to step S535.
When the film thickness of the photoconductor 1 is the threshold value 3 or less, in step S530, the charge bias control unit _20c determines the applied voltage of charge to VC.
When the film thickness of the photoconductor 1 is larger than the threshold value 3, in step S535, the charge bias control unit 20c determines the applied voltage of charge to _VD .
The size of the threshold value described above is preset so that the value increases in the order of threshold value 1 <threshold value 2 <threshold value 3.

As a result, by controlling the charge bias to be optimum according to the calculated film thickness of the photoconductor 1, it is possible to avoid applying an excessively high charge bias, and the life of the photoconductor can be extended. Can be kept for a long time.

<Measurement cycle control unit>
FIG. 20 is a chart showing a constant voltage value corresponding to the film thickness of the photoconductor 1.
FIG. 20 shows that when the film thickness of the photoconductor 1 is 15 um or less, 15 um to 25 um, and 25 um or more, the constant voltage Vk value is corrected to 900 V, 1000 V, and 1100 V, respectively.
The measurement cycle control unit 20b may correct a constant charging voltage Vk by referring to the table shown in FIG. 20 according to the film thickness of the photoconductor 1 calculated by the film thickness calculation unit 20e.
Thereby, by correcting the constant charging voltage Vk according to the film thickness of the photoconductor 1, the residual potential of the photoconductor 1 after static elimination can be made constant.
As described above, it is possible to control the optimum surface potential of the film thickness of the photoconductor according to the deterioration over time.

<Summary of Actions and Effects of Examples of Embodiments>
<First aspect>
In the image forming apparatus 100 of this embodiment, the voltage applying unit 22a for applying a charging bias to the charging roller 2 for charging the peripheral surface of the orbiting photoconductor 1 and the charging roller 2 when the charging bias is applied to the charging roller 2 The current detection unit 22b that generates a feedback signal representing the output current flowing from the photoconductor 1 to the photoconductor 1, the control unit 20 that controls the voltage application unit 22a based on the feedback signal generated by the current detection unit 22b, and the photoconductor 1 The image forming apparatus 100 includes a static eliminator 7 for eliminating static current and a temperature detecting unit 25 for detecting the environmental temperature, and the control unit 20 sequentially in one measurement cycle according to the environmental temperature. The voltage application unit 22a is controlled so that the corrected charging voltage Vk is applied to the charging roller 2, the static eliminator 7 is controlled to be statically eliminated, and the voltage application unit 22a is controlled so that the charging bias is applied to the charging roller 2. The measurement cycle control unit 20b and the measurement cycle control unit 20b that control the current detection unit 22b to detect the output current when the charging bias is applied to the charging roller 2 and control the static eliminator 7 to eliminate static electricity. On the other hand, when a plurality of measurement cycles are continuous , the IV characteristic composed of the output current represented by the feedback signal and the charging bias applied by the voltage application unit in each measurement cycle. It is characterized by including a charge bias control unit 20c that controls the charge bias differently in order to guide the charge bias.
According to this aspect, the voltage application unit 22a is controlled so that the charging voltage Vk corrected according to the environmental temperature is sequentially applied to the charging roller 2 during one measurement cycle, and the static eliminator 7 eliminates static electricity. The voltage application unit 22a is controlled so that the charging bias is applied to the charging roller 2, and the current detection unit 22b is controlled so as to detect the output current when the charging bias is applied to the charging roller 2. By controlling the electric device 7 to eliminate static electricity, the residual potential of the photoconductor 1 after static elimination can be made constant.
Further, when a plurality of measurement cycles are continuous with respect to the measurement cycle control unit 20b, the output current represented by the feedback signal and the charge bias applied by the voltage application unit are used in each measurement cycle. By controlling the charging bias differently in order to derive the configured IV characteristics, the voltage and charging of the charging bias applied accurately after the residual potential of the photoconductor 1 after static elimination becomes constant. It is possible to detect the current when a bias is applied.
From the above, the slope of the charged IV characteristic can be accurately calculated.

<Second aspect>
The charge bias control unit 20c of this embodiment controls the measurement cycle control unit 20b so that when a plurality of measurement cycles are continuous, the charge bias in the subsequent measurement cycle is sequentially higher than the preceding measurement cycle. It is characterized by that.
According to this aspect, when a plurality of measurement cycles are continuous, the charge bias in the subsequent measurement cycle is controlled to be sequentially higher than the preceding measurement cycle, so that the voltage and charge of the charge bias applied with high accuracy are obtained. It is possible to detect the current when a bias is applied.

<Third aspect>
The charge bias control unit 20c of this embodiment controls the measurement cycle control unit 20b so that the charge bias in the subsequent measurement cycle is sequentially lower than the preceding measurement cycle when a plurality of measurement cycles are continuous. It is characterized by that.
According to this aspect, when a plurality of measurement cycles are continuous, the charge bias in the subsequent measurement cycle is controlled to be sequentially lower than the preceding measurement cycle, so that the voltage and charge of the charge bias applied with high accuracy are obtained. It is possible to detect the current when a bias is applied.

<Fourth aspect>
In the image forming apparatus 100 of this embodiment, the voltage detecting unit 22c for detecting the residual voltage remaining in the photoconductor 1 after the static eliminator 7 is activated, and the measurement cycle control unit 20b have a threshold value of the detected residual voltage. If the residual voltage does not exceed the threshold value, the operation of applying the charging voltage Vk corrected according to the environmental temperature to the charging roller 2 by the voltage applying unit 22a is skipped. And.
According to this aspect, when the detected residual voltage does not exceed the threshold value, the control time is shortened by skipping the operation of applying the charging voltage Vk corrected according to the environmental temperature to the charging roller 2. be able to.

< Fifth aspect>
The control unit 20 of this embodiment is a film thickness calculation unit that calculates the film thickness of the photoconductor 1 based on the IV characteristic composed of the output current represented by the feedback signal and the charging voltage applied by the voltage application unit 22a. It is characterized by having 20e.
According to this aspect, the film thickness state of the photoconductor 1 is determined by calculating the film thickness of the photoconductor 1 based on the IV characteristic composed of the output current represented by the feedback signal and the applied charging voltage. Can be recognized.

< Sixth aspect>
The control unit 20 of this embodiment is characterized by including a photoconductor life determination unit 20f for determining the optimum life of the photoconductor 1 based on the film thickness of the photoconductor 1 calculated by the film thickness calculation unit 20e. ..
According to this aspect, since the optimum life of the photoconductor 1 is determined based on the calculated film thickness of the photoconductor 1, it is possible to determine the life of the photoconductor 1 according to the individual state of the photoconductor 1, according to the prior art. The life of the photoconductor 1 can be measured with higher accuracy than the estimation method.

< 7th aspect>
The charge bias control unit 20c of the present embodiment is characterized in that the charge bias is controlled so as to be optimum according to the film thickness of the photoconductor 1 calculated by the film thickness calculation unit 20e.
According to this aspect, by controlling so that the charging bias is optimized according to the calculated film thickness of the photoconductor 1, it is possible to avoid applying an excessively high charging bias, and the photoconductor. Can keep the life of the product for a long time.

< 8th aspect>
The image forming apparatus 100 of this embodiment includes a storage unit 24 that stores in advance a data table showing the relationship between the IV characteristics and the film thickness, and the film thickness calculation unit 20e is the charging voltage applied by the voltage application unit 22a. It is characterized in that a gradient related to an IV characteristic composed of an output current represented by a feedback signal is calculated, and a film thickness corresponding to the gradient is calculated from a data table of the storage unit 24.
According to this aspect, the film thickness is detected by calculating the slope related to the IV characteristic composed of the applied charging voltage and the output current, and calculating the film thickness corresponding to the slope calculated from the data table. The calculation load of time can be reduced.

< 9th aspect>
The measurement cycle control unit 20b of the present embodiment is characterized in that the charging voltage Vk corrected according to the environmental temperature is corrected according to the film thickness of the photoconductor 1 calculated by the film thickness calculation unit 20e.
According to this aspect, the residual potential of the photoconductor 1 after static elimination can be made constant by correcting the charging voltage Vk corrected according to the environmental temperature according to the film thickness of the photoconductor 1.

<10th aspect>
The image forming method of this embodiment is performed from a voltage application unit 22a that applies a charging bias to the charging roller 2 that charges the peripheral surface of the orbiting photoconductor 1, and a charging roller 2 that applies the charging bias to the charging roller 2. The current detection unit 22b that generates a feedback signal representing the output current flowing through the photoconductor 1, the control unit 20 that controls the voltage application unit 22a based on the feedback signal generated by the current detection unit 22b, and the photoconductor 1 An image forming method using an image forming apparatus 100 including a static eliminator 7 for static elimination and a temperature detecting unit 25 for detecting an environmental temperature, wherein the control unit 20 responds to the environmental temperature during one measurement cycle. The voltage application unit 22a is controlled so that the corrected charging voltage Vk is applied to the charging roller 2, the static eliminator 7 is controlled to eliminate static electricity, and the voltage application unit 22a is applied so as to apply a charging bias to the charging roller 2. A measurement cycle control step (FIG. 15, S100) that controls the current detection unit 22b to detect the current when the charging bias is applied to the charging roller 2 and controls the static eliminator 7 to eliminate static electricity. When a plurality of measurement cycles are continuous with respect to the measurement cycle control step, the output current represented by the feedback signal and the charging bias applied by the voltage application unit are configured in each measurement cycle. It is characterized by comprising a charge bias control step (FIG. 15, S20) for controlling the charge bias differently in order to derive the IV characteristic .
Since the operation and effect of the tenth aspect are the same as those of the first aspect, the description thereof will be omitted.

< 11th aspect>
The program of this aspect is a program characterized by causing a processor to execute each step in the image forming method according to the tenth aspect.
According to this aspect, each step can be executed by the processor.

1 ... Photoreceptor, 2 ... Charging roller, 3 ... Exposure section, 4 ... Developing section, 5 ... Transfer roller, 6 ... Blade, 7 ... Static eliminator, 8 ... High voltage power supply, 9 ... Output feedback section, 10 ... Control unit, 10a ... A / D conversion unit, 20 ... control unit, 20a ... drive control unit, 20b ... measurement cycle control unit, 20c ... charge bias control unit, 20d ... determination unit, 20e ... film thickness calculation unit, 20f ... photoconductor life Judgment unit, 21 ... Photoreceptor drive unit, 22 ... Charging unit, 22a ... Voltage application unit, 22b ... Current detection unit, 22c ... Voltage detection unit, 23 ... Transfer unit, 23a ... Voltage application unit, 23b ... Roller drive unit, 24 ... Storage unit, 25 ... Temperature detection unit, 100 ... Image forming device

Japanese Patent No. 6043739 Japanese Patent No. 3064643

Claims (11)

A voltage application unit that applies a charging bias to the charging member that charges the peripheral surface of the orbiting photoconductor,
A current detection unit that generates a feedback signal representing an output current flowing from the charging member to the photoconductor when the charging bias is applied to the charging member.
A control unit that controls the voltage application unit based on the feedback signal generated by the current detection unit, and a control unit.
With the static elimination means for eliminating static electricity from the photoconductor,
A temperature detector that detects the environmental temperature and
It is an image forming apparatus equipped with
The control unit
During one measurement cycle, the voltage application unit is controlled so as to sequentially apply a charging voltage corrected according to the environmental temperature to the charging member, and the static elimination means is controlled to eliminate static electricity, and the charging is performed. The voltage application unit is controlled so as to apply a bias to the charging member, the current detection unit is controlled so as to detect the output current when the charging bias is applied to the charging member, and the static elimination means A measurement cycle control unit that controls static elimination,
When a plurality of measurement cycles are continuous with respect to the measurement cycle control unit, the output current represented by the feedback signal and the charging bias applied by the voltage application unit are configured in each measurement cycle. An image forming apparatus comprising: a charge bias control unit that controls the charge bias differently in order to derive the IV characteristic . The charge bias control unit controls the measurement cycle control unit to sequentially control the charge bias in the subsequent measurement cycle to be higher than the preceding measurement cycle when a plurality of measurement cycles are continuous. The image forming apparatus according to claim 1. The charge bias control unit controls the measurement cycle control unit to sequentially lower the charge bias in the subsequent measurement cycle from the preceding measurement cycle when a plurality of measurement cycles are continuous. The image forming apparatus according to claim 1. A voltage detection unit that detects the residual voltage remaining in the photoconductor after the static elimination means is activated, and
The measurement cycle control unit determines whether or not the detected residual voltage exceeds the threshold value, and if the residual voltage does not exceed the threshold value, the voltage application unit corrects it according to the environmental temperature. The image forming apparatus according to claim 1, wherein the operation of applying the charged charging voltage to the charging member is skipped. The control unit is a film thickness calculation unit that calculates the film thickness of the photoconductor based on the IV characteristic composed of the output current represented by the feedback signal and the charging voltage applied by the voltage application unit. The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is provided. The fifth aspect of claim 5 is characterized in that the control unit includes a photoconductor life determination unit that determines the optimum life of the photoconductor based on the film thickness of the photoconductor calculated by the film thickness calculation unit. Image forming device. The image forming apparatus according to claim 5, wherein the charge bias control unit controls the charge bias so as to be optimized according to the film thickness of the photoconductor calculated by the film thickness calculation unit. .. It is provided with a storage unit that stores in advance a data table showing the relationship between the IV characteristics and the film thickness.
The film thickness calculation unit calculates a slope related to the IV characteristic composed of the charging voltage applied by the voltage application unit and the output current represented by the feedback signal, and the slope is calculated from the data table of the storage unit. The image forming apparatus according to claim 5, wherein the film thickness corresponding to the above is calculated. The fifth or claim is characterized in that the measurement cycle control unit corrects the charging voltage corrected according to the environmental temperature according to the film thickness of the photoconductor calculated by the film thickness calculation unit. 8. The image forming apparatus according to 8. A voltage application unit that applies a charging bias to the charging member that charges the peripheral surface of the orbiting photoconductor,
A current detection unit that generates a feedback signal representing an output current flowing from the charging member to the photoconductor when the charging bias is applied to the charging member.
A control unit that controls the voltage application unit based on the feedback signal generated by the current detection unit, and a control unit.
With the static elimination means for eliminating static electricity from the photoconductor,
A temperature detector that detects the environmental temperature and
It is an image forming method by an image forming apparatus equipped with.
The control unit
During one measurement cycle, the voltage application unit is controlled so that the charging voltage corrected according to the environmental temperature is applied to the charging member, the static elimination means is controlled to eliminate static electricity, and the charging bias is applied. The voltage application unit is controlled so as to be applied to the charging member, the current detection unit is controlled so as to detect the output current when the charging bias is applied to the charging member, and the static elimination means eliminates static electricity. And the measurement cycle control step to control
When a plurality of measurement cycles are continuous with respect to the measurement cycle control step, the output current represented by the feedback signal and the charging bias applied by the voltage application unit are configured in each measurement cycle. An image forming method comprising: a charge bias control step for controlling the charge bias differently in order to derive the IV characteristic . A program according to claim 10, wherein each step in the image forming method is executed by a processor.

Images